MIKIW 2026 Oral Presentation Abstracts |
Author: Rachel Crawford Non-Presenting Authors: Ethan J Anderson Title: Beyond H2O2: Carnosine scavenging and bioenergetic consequences of catecholamine metabolites in the heart Abstract: Outside the central nervous system, catecholamines are metabolized almost exclusively by monoamine oxidase (MAO), an enzyme localized to the mitochondrial outer membrane. Increased MAO activity has been documented in multiple neurodegenerative and cardiometabolic diseases and is associated with several forms of heart failure. Oxidative deamination of norepinephrine (NE) by MAO produces hydrogen peroxide (H2O2), ammonia (NH4+), and the catecholaldehyde 3,4-dihydroxyphenylglyoclaldehyde (DOPEGAL). Prior work on MAO has focused primarily on oxidative stress from H2O2 production, while effects from NH4+ and catecholaldehydes have been largely overlooked. We have shown that the histidyl dipeptide carnosine readily forms stable conjugates with DOPEGAL. Additionally, given the metabolic role of NH4+, we hypothesized that MAO-derived NH4+ influences cardiac mitochondrial bioenergetics. Effects of MAO-derived NH4+ on cardiac mitochondria were evaluated by measuring respiration (JO2), ATP synthesis (JATP), and redox state in mitochondria isolated from wild-type (WT) and cardiomyocyte-specific MAO-A deficient (cMAO-Adef) mice. Respiration was assessed under phosphorylating conditions (0.1 mM ADP) with NE or NH4+ (5-10 µM). We also evaluated carnosine-mediated scavenging of catecholaldehydes in primary cardiomyocytes using LC-MS/MS detection of DOPEGAL–carnosine conjugates following NE and carnosine exposure ± MAO inhibitors. NE increased glutamate-supported JO2 by ~15%; this effect was abolished in cMAO-Adef mitochondria and by MAO inhibition. NH4+ recapitulated this response. NE did not alter ATP synthesis but increased NADH levels by ~20% in WT mitochondria; this effect was attenuated in cMAO-Adef groups. LC-MS/MS detected DOPEGAL-carnosine conjugates in conditioned media, which were eliminated by MAO inhibition. These findings indicate that MAO-derived NH₄⁺ enhances glutamate-supported mitochondrial respiration, revealing a previously unrecognized pathway linking MAO-mediated catecholamine metabolism with mitochondrial NADH cycling. Detection of DOPEGAL-carnosine adducts confirms effective catecholaldehyde scavenging by carnosine in cardiomyocytes, establishes a novel biomarker of MAO activity, and supports further development of carnosine as a therapy for cardiovascular and neurodegenerative diseases. |
Author: Josephine Anderson Non-Presenting Authors: Ya’el Courtney, Christian Lagares Linares, Cody J. Wenthur, Maria K. Lehtinen Title: Maternally administered LSD rapidly reaches embryonic CSF and is associated with altered cortical development and adult behavior in mice Abstract: Psychedelics have been moving through clinical trials for their potential as therapeutics to treat a variety of mental illnesses. Notably, Lysergic Acid Diethylamide (LSD), has demonstrated efficacy in the treatment of Generalized Anxiety Disorder (GAD) and is slated to undergo a Phase 3 Clinical Trial later this year. However, the safety profile of LSD is underexplored. Due to the importance of serotonin in fetal development, it is critical to investigate maternal LSD ingestion and subsequent fetal safety. The last papers regarding the effects of LSD on fetal development were published 50 years ago, and they often come to contradictory conclusions using the outdated technology available at the time. In order to fill this literature gap, we completed a series of pharmacokinetic, behavioral, and developmental studies in mice (CD1 and C57Bl/6). To study maternal-fetal transfer of LSD and the potential effects on offspring, pregnant mice were administered 0.3mg/kg of LSD via subcutaneous injection. Acute exposure was modelled via a single injection at E12.5 and chronic was modelled via an injection daily from E12.5-E16.5. We found LSD readily crosses the placenta and enters the fetus. Approximately 5% of maternally administered LSD reaches the fetal CSF, peaking at 15 minutes post administration. This exposure was sufficient in both our acute and chronic exposure models to induce excitatory neuron remodeling at postnatal day 8. Exposed offspring that reached adulthood exhibited lasting behavioral changes such as poor sensorimotor gating and increased instances of rotational stereotypy. Interrogating more translational doses through pharmacokinetic study is challenging due to the very low doses LSD is typically administered at, and it does not persist long in the body. To overcome this hurdle, we are now also pursuing PBPK modelling. Our research has begun to elucidate the potential effects of LSD on fetal development. However, there is much more work to be done in order to understand the effects of LSD and other serotonergic drugs in this vulnerable population as psychedelic drugs near FDA approval. |
Author: Kelsey Holdaway Non-Presenting Authors: Erik Faber, Naresh Gantasala, Jerrett Holdaway, Gunda Georg Title: Development of Covalent-Allosteric Inhibitors of Cyclin-Dependent Kinase 2 Abstract: In ovarian and breast cancers, cyclin-dependent kinase 2 (CDK2) is hyperactivated. Genetic ablation studies have demonstrated that loss of CDK2 suppresses tumor growth, establishing CDK2 as a compelling target. No selective CDK2 inhibitor has advanced through clinical trials, largely due to challenges in achieving kinase selectivity. Our lab has developed selective, allosteric CDK2 inhibitors with single-digit nM affinities. However, biochemical characterization revealed a negatively cooperative relationship with cyclin association, resulting in diminished enzyme inhibition at elevated cyclin concentrations. To overcome this limitation, we pursued the development of covalent-allosteric CDK2 inhibitors that irreversibly bind and inactivate CDK2 independently of cyclin levels. We have synthesized a library of inhibitors with varying warhead reactivities and trajectories toward CDK2. Intact protein mass spectrometry has confirmed covalent adduct formation. Selectivity profiling indicates that kinase selectivity is largely preserved relative to the parent non-covalent scaffold, which showed exceptional selectivity in a kinome-wide screen. Time-dependent enzyme kinetics are consistent with a covalent mechanism of action and allosteric target engagement was independently verified. The inhibitors overcome cyclin-dependent negative cooperativity and maintain robust enzyme inhibition in fixed-time-point assays. Cellular activity was demonstrated by dose-dependent suppression of downstream retinoblastoma protein phosphorylation. The covalent inhibitors exhibit anti-proliferative effects across multiple ovarian and breast cancer cell lines, achieving cytotoxic IC50 values of 1 µM. Washout experiments revealed no shift in IC50 values following compound removal, indicating sustained target engagement. Notably, the inhibitors retain anti-proliferative activity across parental MCF-7 cells and multiple therapy-resistant derivatives, highlighting the potential to overcome resistance mechanisms. Collectively, the data establish covalent-allosteric inhibition as a promising strategy to overcome cyclin-mediated negative cooperativity while maintaining selectivity and supports further development of this class of CDK2 inhibitors as potential therapeutic leads. |
Author: Mario Alvarez Non-Presenting Authors: Alexander S. Mankin, Nora Vásquez-Laslop, Terry W. Moore Title: Hybridization of Type II Proline-Rich Antimicrobial Peptides as a Strategy for the Evaluation of Translation Termination Inhibitors Abstract: The increasing prevalence of antibiotic resistance highlights the need for antibacterial agents with novel mechanisms of action. Type II proline-rich antimicrobial peptides (PrAMPs) represent promising translation-targeting leads that inhibit translation termination through release factor sequestration; however, challenging structure–activity relationships, the limited number of characterized termination inhibitors, and liabilities associated with peptide therapeutics have hindered their development. To address these limitations, we investigated scaffold hybridization between sequence-distinct translation-termination inhibitors. Specifically, we hybridized the recently identified Type II PrAMP Pdi1 with Drosocin and prepared a library of peptides that incorporate the pharmacophores of both inhibitors. We found that hybridization identified unexpected differences in Pdi1 structure–activity relationships relative to related PrAMPs. Inverse hybrids lost activity, demonstrating that bioactivity is strongly sequence-dependent and dictated by the pharmacophore. We identified a promising hybrid scaffold and observed a negative correlation between N-terminal polarity and antibacterial activity, in contrast to trends reported for related analogs. Collectively, our results establish scaffold hybridization as an effective strategy for evaluating PrAMP chemical space and developing useful tool compounds to assess this promising mechanism of action. |
Author: Tristan Sprague Non-Presenting Authors: Michael Wolfe Title: Cholesterol regulates γ-secretase catalysis by alleviating stalled enzyme-substrate complexes: Implications for Alzheimer’s disease pathogenesis Abstract: Cholesterol regulates γ-secretase catalysis by alleviating stalled enzyme-substrate complexes: Implications for Alzheimer’s disease pathogenesis Tristan A. Sprague1, Michael S, Wolfe2 1Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA; 2Department of Medicinal Chemistry, University of Kansas, Lawrence, KS, USA The protease γ-secretase is an important target for cancer and Alzheimer’s disease. However, our understanding of γ-secretase’s normal regulation is still limited. γ-Secretase is a membrane protein, and thus is sensitive to membrane composition. The γ-secretase/membrane relationship is especially relevant to sporadic Alzheimer’s disease, which often coincides with impaired cholesterol metabolism. Membrane cholesterol is known to affect γ-secretase, but the exact mechanism is still unknown. Cholesterol greatly bolsters γ-secretase’s proteolytic activity as cholesterol membrane content increases in a liposome-based purified γ-secretase assay. We show that cholesterol increases the enzyme’s kcat over 10-fold, while γ-secretase’s substrate affinity remains unchanged. Decreased membrane cholesterol causes γ-secretase ES complex stalling similar to that caused by Alzheimer’s-associated mutations in γ-secretase. Depleting cholesterol in cultured cells increases γ-secretase stalling, as measured by a fluorescence lifetime imaging assay. These results demonstrate that cholesterol acts as a γ-secretase activator, and that insufficient cholesterol leads to γ-secretase stalling. As cholesterol distribution is altered in sporadic Alzheimer’s disease, these results suggest a manner of γ-secretase dysregulation that is biochemically similar to Alzheimer’s disease arising from direct mutations in γ-secretase.
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Author: Michael Garcia-Mares Non-Presenting Authors: Jon Doorn, Sarah Preston Title: Human-relevant PCB52 metabolites trigger mitochondria-dependent bioenergetic collapse in glia Abstract: Background and Purpose: Lower-chlorinated polychlorinated biphenyls (LC-PCBs) are persistent environmental toxicants associated with developmental neurotoxicity, with rising concern due to inhalation exposure. A major gap is how glial bioenergetics shapes PCB-driven injury, particularly for human-relevant PCB metabolites. Because astrocytes buffer neuronal metabolism, mitochondrial disruption in astrocytes may represent an early, upstream event in PCB neurotoxicity. We investigated PCB-52 and major human-relevant hydroxylated and sulfated metabolites in differentiated C6 astroglioma cells to define an astrocyte-like, metabolism-relevant vulnerability profile. Methods: C6 cells were differentiated with dibutyryl-cyclic AMP and theophylline to induce an astrocyte-like phenotype, confirmed by increased GFAP expression (immunofluorescence). Cells were challenged with PCB-52 and metabolites, and bioenergetic fragility was unmasked by comparing ATP responses under glucose (glycolytic buffering permitted) versus galactose (OXPHOS dependence enforced). ATP was quantified by a luciferase-based assay across acute and longer exposure windows, and a glucose:galactose ATP ratio was used as a mechanistic classifier of mitochondrial dependence. Imaging-based snapshots (CellROX, MitoSOX, and DAF-FM) were used to spatially resolve redox and signaling responses. Results: Differentiated astrocyte-like C6 cells showed increased susceptibility to PCB-52 compared with undifferentiated cells, with metabolites producing stronger injury in the differentiated state. ATP was largely preserved under glucose but collapsed under galactose in a treatment-dependent manner, indicating that glycolysis can mask early mitochondrial dysfunction. The glucose:galactose ATP ratio separated generalized redox stress from mitochondrial toxicants and placed the hydroxylated metabolite in the mitochondrial-toxicant class. Imaging supported a mitochondrial mode of action: mitochondrial superoxide increased strongly despite minimal early cell-wide ROS, with reactive nitrogen species emerging as a potential downstream response. In separate rescue experiments, pharmacologic NRF2 activation mitigated PCB-associated cytotoxicity, including protection by a fraxinellone-derived NRF2 activator were explored. Conclusions: These findings support a model in which PCB-52 metabolites preferentially compromise glial mitochondrial/redox bioenergetics, producing ATP failure when OXPHOS demand is imposed. Astrocyte-like metabolic state meaningfully alters toxicodynamic responses and should be incorporated into human-relevant neurotoxicity assessment. |
Author: Julia Lee Non-Presenting Authors: Ziwei Hu, Jian-Xing Ma, and Adam S. Duerfeldt Title: Design, Synthesis, And Evaluation of Small Molecule Leads for Diabetic Retinopathy Abstract: Diabetic retinopathy (DR) is a severe complication of diabetes that affects over one-third of diabetics. Standard of care (anti-VEGF injections) is invasive and fails to address ~40% of the patient population.1 These factors, paired with the increased prevalence of diabetes, inspired us to develop mechanistically differentiated small molecules as potential systemically available options for DR. Fenofibric acid, the active metabolite of fenofibrate and a known peroxisome proliferator-activated receptor alpha (PPARα) agonist, significantly reduces DR progression, as demonstrated in three large independent clinical trials (FIELD, ACCORD and LENS).2–4 Fenofibric acid, however, lacks selectivity and exhibits poor potency.5 Additionally, the requirement for high doses of fenofibrate to achieve clinical efficacy is associated with undesired side effects, suggesting that fenofibric acid may not be an optimal candidate for repurposing as a treatment or DR.6 Recently, we published a novel biphenyl aniline PPARα agonistic chemotype, which exhibits improved sub-type selectivity and potency for PPARα, increases cell viability in chemical challenge models, reduces VEGF secretion, and attenuates the release of reactive oxygen species in DR relevant cell-based models.7 Despite these advances, we speculated that the aniline scaffold may present metabolic liabilities and poor aqueous solubility. To address these limitations, we investigated amide-based analogs as an alternative strategy. Initial replacement of the aniline linker with an amide resulted in a significant loss of potency for PPARa, underscoring the sensitivity of receptor engagement to linker identity. Guided by systematic structure-activity relationship (SAR) studies, iterative optimization of linker architecture and substituent patterns restored PPARα agonism and led to analogs with improved potency, solubility, and metabolic stability. This talk will describe the design and SAR of the amide series and highlight key structural determinants governing PPARα activity and drug-like properties. |
Author: Ana Lopez-Hernandez Non-Presenting Authors: Lisa E. Rusali, Leonardo Lugo, June Chow, and Andrew P. Riley Title: Development of a Direct-to-Biology Pipeline for Aristoquinoline Analogues Abstract: With the rising unmet medical need for treatments of substance use disorder, there is increasing interest in the α3β4 nicotinic acetylcholine receptors (nAChRs). Work by our lab and others has determined that inhibitors of the α3β4 nAChRs are effective in multiple rodent models of substance use disorders. Building on this work, we have been investigating the structure-activity relationship (SAR) of the moderately selective antagonist aristoquinoline, an Aristotelia alkaloid, to identify compounds with improved α3β4 potency and selectivity. While this traditional approach has successfully identified several promising derivatives, we recently designed a direct-to-biology (D2B) pipeline to accelerate our SAR studies. By avoiding time consuming purifications steps, D2B workflows are increasingly being applied to synthesize and evaluate larger libraries of molecules to identify promising leads. By establishing and optimizing our D2B pipeline, we have synthesized >100 analogues of aristoquinoline and analyzed their activity against the α3β4 nAChR subtype in a calcium influx bioassay. Our results indicate that the unpurified reaction mixtures produce comparable biological activity when compared to their purified counterparts. Through this approach, we rapidly identified several analogues with improved potency relative to aristoquinoline, thereby demonstrating our D2B pipeline is a highly beneficial tool capable of providing compounds and drug leads for therapeutic treatments for substance use disorder. |
Author: Farjana Afroj Non-Presenting Authors: Steven Bloom Title: PeptiDEL Technology: Synthesis of Peptide-Based DNA Encoded Library Abstract: Peptides occupy a unique position as therapeutic agents, bridging conventional small molecules and larger proteins. Traditional methods used to discover peptides rely on ‘display’ techniques, e.g., phage-, mRNA-, and ribosome-display. Newer methods have evolved to use DNA as a screening platform, assembling collections of peptides on-DNA through iterative cycles of individual amino acid couplings and DNA elongation. But this approach is limited to those amino acids that can be readily procured and coupled, minimizing the structural diversity of the library. To broaden the complexity of peptides that can be made on-DNA, a new approach is reported that uses dehydroalanine (Dha) residues as a modular handle to embed any amino acid (natural or unnatural), giving rise to complete polypeptides over several parallel steps. The resulting library can be used to identify lead peptides for new drug targets. |
Author: Kailey Said-Lathrum Non-Presenting Authors: Henry Lin, Grace Rocco, Ben Stimson, Ryan Boudreau, Kris DeMali, Isabella Grumbach, Kamal Rahmouni, Jared McLendon Title: Sorbs2 regulates vascular smooth muscle cell phenotype plasticity and vascular tone Abstract: Objective: Sorbs2 is a cytoskeletal adapter protein that is highly expressed in vascular smooth muscle cells (VSMCs) and is dysregulated in cardiovascular disease. Our objective is to understand the role of Sorbs2 in vascular biology. Hypothesis: Sorbs2 regulates VSMC proliferative and contractile phenotypes. Methods and Results: To test if Sorbs2 regulates VSMC proliferation in vitro, two growth curves were performed. Primary VSMCs from Sorbs2-flox/flox mice were transduced with Ad5-GFP control or Ad5-CRE for acute knock out (n=6), or VSMCs were isolated from Sorbs2 WT (WT) and Sorbs2 KO (KO) mice (n=5). Both KO models showed decreased proliferation at 48 and 72 hours compared to WT (p<0.01). To test Sorbs2’s role in an in vivo vascular proliferation and remodeling model, WT and KO mice underwent carotid artery ligation surgery. RNA seq analysis revealed that KO arteries primarily upregulate immune pathways in response to ligation injury whereas WT did not (n=3). Unligated KO carotid arteries showed compensatory upregulation of cytoskeletal contractile genes compared to WT. To test if Sorbs2 regulates vascular contractility, we performed wire myography experiments. Aortic force of contraction from WT and KO mice was measured in response to increasing phenylephrine (PE) dose. KO aortas showed increased PE-induced contractility compared to WT (n=6). In passive length-tension relationships, KO aortas showed lower passive tension than WT, suggesting Sorbs2 plays a role in maintaining the VSMC structural cytoskeleton. To test the effects of Sorbs2 knockout on vascular tone in vivo, we performed radiotelemetry on WT and KO mice. Blood pressure radio telemeters were installed, and mice were treated with Angiotensin II (AngII) for 10 days to induce hypertension. KOs showed a reduced change in mean arterial blood pressure (∆MAP) after AngII administration relative to WT. However, after 5 days post-AngII administration, KOs increased in ∆MAP relative to WT, potentially through compensatory mechanisms. Conclusion: Our results suggest Sorbs2 is a novel regulator of VSMC phenotype plasticity and is involved in VSMC structural and contractile responses. |
Author: Yuan Zhao Non-Presenting Authors: Eun Seo Choi, Fei Sun, Regina Stasser de Gonzalez, Yaxian Liao, Chunrong Li, Florence M. Brunel, Nick Cox, Joseph Stock, Guangsen Fu, Wenxin Wu, Penghsuan Huang, Ramesh Mudududdla, Eric V. Shusta, Lingjun Li, Ting Fu, Alexander N. Zaykov, and Weiping Tang Title: LRP1-Targeting Chimeras for Degradation of Extracellular Secreted and Membrane Proteins Abstract: Targeted protein degradation (TPD) is an emerging therapeutic strategy that leverages endogenous degradation machinery to eliminate disease-associated proteins. By conjugating a targeted protein binder to a lysosome targeting receptor (LTR) binder, these chimeric molecules facilitate the internalization and trafficking of the targeted protein into the lysosome for degradation. In this work, we present a series of chimeric molecules that use peptide to recruit low-density lipoprotein receptor-related protein 1 (LRP1) as the LTR, thereby promoting the degradation of the targeted protein. Our results demonstrate that these peptide-based degraders efficiently induce the internalization and degradation of extracellular soluble and membrane pro-teins, including NeutrAvidin, EGFR, PD-L1, and CD47. We further show that peptide-conjugated antibody degraders can penetrate a 3D tumor model, induce protein degradation, and suppress tumor-cell invasion. Using an in vitro blood–brain barrier (BBB) model, we also demonstrate that they exhibit enhanced transcytosis efficiency across brain microvascular endothelial cells (BMECs). Taken together and given the high expression of LRP1 in the BBB and central nervous system (CNS), these degraders hold potential for the treatment of CNS-related disorders. |
Author: Laura Hirsch Non-Presenting Authors: Jian Tang, Ella S. Haefner, Brenner J. Klein, Ramkumar Moorthy, Samuel Syberg and Daniel A. Harki Title: Development of Highly Potent and Selective Dual Degraders of Aurora Kinase A and N-Myc for Neuroblastoma Therapy Abstract: Dysregulation and overexpression of MYCN, which encodes the oncotranscription factor N-Myc, is a bona fide driver of neuroblastoma (NB), a neuroendocrine tumor that predominantly affects children. In fact, NB is the most prevalent tumor in infants, and the most common extra-cranial solid tumor in children. Children with genetic amplification of MYCN have a 5-year survival rate of ~50%. Drugging N-Myc directly is ideal; however, N-Myc lacks enzymatic activity and is intrinsically disordered, which hinders the rational design and development of small molecule inhibitors. One method to reduce N-Myc signaling is to reduce protein levels in cellulo. In healthy cells, N-Myc protein abundance is tightly regulated and rapidly turned-over. However, in MYCN-amplified NB, N-Myc abundance is greatly potentiated due to stabilization by a protein-protein interaction with Aurora Kinase A (Aurora-A). We have developed heterobifunctional molecules that target Aurora-A for degradation in NB cells. Our first-generation degrader, HLB-0532259, results in potent Aurora-A and N-Myc degradation in MYCN-amplified NB cells (Tang et al., Cell Chem. Biol. 2025). HLB-0532259 exhibits an extremely selective degradation profile, and in vivo tumor reduction. Unfortunately, HLB-0532259 displays poor solubility and off-target cytotoxicity in mice. To address these issues, we developed next-generation degraders with varying linkers to optimize physiochemical properties and degradation potency. Our lead compound from these efforts, HLB-0535074, shows superior degradation potency (DC50 = 7.0 nM Aurora-A; 13.5 nM N-Myc), long exposure selectivity, apoptosis induction, and NB cytotoxicity, surpassing that of HLB-0532259. This presentation highlights our ongoing effort to understand and improve Aurora-A/N-Myc dual degraders in MYCN-amplified NB with an eye towards clinical implementation. |
Author: Luke Harding Non-Presenting Authors: Samuel Y. Aboagye, Gabriele Federica, Marta Paterma, Shenell Brown, Francesco Angelucci, David L. Williams, Pavel A. Petukhov Title: Design, synthesis, and biological evaluation of novel benzodiazepines as thioredoxin glutathione reductase inhibitors for the eradication of schistosomiasis Abstract: Schistosomiasis is a devastating and neglected parasitic disease caused by schistosome blood flukes and kills 200,000 people annually. Our team has identified a novel approach to treat infections by disrupting worm redox machinery through noncovalent inhibition of an essential flavoenzyme, thioredoxin glutathione reductase (TGR), via binding to an allosteric site, the “doorstop pocket”. Herein is the report of the medicinal chemistry of a series of benzodiazepines that are potent inhibitors of TGR in S. mansoni (SmTGR) and cause worm death ex vivo. Investigating the SAR at C3 on the diazepine core, the two-methylene-linked tert-butyl ester 4h was the most potent inhibitor in the series, inhibiting SmTGR with an IC50 of 10.7 µM ± 0.39. Homologation of the methylene linker, bioisosteric replacement of the tert-butyl ester with an amide or carboxylic acid, and reduction of the C5 phenyl ring all resulted in the loss of inhibition. In an alternative series of compounds based on the known schistosomicidal benzodiazepine meclonazepam, it was found that substituting the C5 phenyl group with 3-pyridinyl derivatives resulted in marked inhibition. The best compound in this series, 3LH016, containing a 5-chloro-3-pyridinyl ring, inhibited SmTGR with an IC50 of 3.29 ± 0.17 µM, killed newly transformed schistosomula with an LD50 of 24.4 ± 1.6 µM, and has superb mouse liver microsome stability with a t1/2 >60 min. However, 3LH016 has an increased LD50 >50 µM against adult S. mansoni and does not affect the GSH/GSSG ratio in adult S. mansoni worms ex vivo. Both the LD50 and the GSH/GSSG ratio depend on inhibitor permeability, metabolism, on-target activity, and sensitivity to efflux. The psychoactive profile of 3LH016 was investigated using the services provided by the Psychoactive Drug Screening Program at UNC. 3LH016 blocked the binding of [3H]flunitrazepam to the rat brain benzodiazepine site receptor with 34.6% inhibition, which is lower than the 61.9% inhibition by meclonazepam which has known psychoactive activity. A co-crystal structure of 3LH016 and hTrxR, an isoform of SmTGR, suggests that 3LH016 may bind a site remote from the “doorstop pocket”. Finally, to combine the results from the C3 and meclonazepam studies, the tert-butyl ester analog of 3LH016 was synthesized and had an improved SmTGR potency of 5.3 µM ± 0.10. |
Author: Krishna Chaitanya Gurajala Non-Presenting Authors: Elijah Barnes, Luke N. Erber Title: Investigation of Glyoxal Induced DNA-Protein Crosslinking Abstract: Glyoxal (GO) is a highly electrophilic dicarbonyl produced endogenously through auto-oxidation of glycolic products and peroxidation of lipids. GO can modify nucleophilic sites within proteins and DNA, resulting in formation of advanced glycation end-products (AGEs). GO-induced AGEs are thought to be responsible for contributing to diabetes progression and have been linked to long-term diabetic complications such as blindness, renal and vascular diseases, and cancer. We hypothesize GO can form harmful DNA-protein cross-links (DPCs), which are formed through covalent conjugation between DNA and proteins. These crosslinks are highly toxic and, if not repaired, result in DNA replication blockage, cytotoxicity, mutagenicity & carcinogenesis. In the present work, we used the ARK (Advanced Recovery of K-SDS precipitates) assay to demonstrate that human cells exposed to glyoxal form DPCs. We isolated DPCs from GO treated cells using STAR (Superior Method for True DNA-protein Adducts Recovery) assay to identify proteins trapped to DNA. To define the biological impact of GO-induced DPCs, we performed mass spectrometry-based proteomics on the isolated material. Proteins involved in chromatin architecture, replication, transcription, repair, and metabolic regulation were isolated with DNA from GO treated samples. In vitro experiments confirm GO exposure results in DPC formation between DNA and histone proteins. Altogether, this study provides preliminary evidence for GO-mediated DNA-protein cross-linking in cells. This study will serve as a starting place to uncover the link between GO and changes in chromatin architecture, prompting future studies regarding the relevance of these toxic lesions in diabetes, cancer and other diseases linked to elevated GO levels. |
MIKIW 2026 Poster Program |
Poster Session 1 |
Author: Bryan A Magana Non-Presenting Authors: Jacob A. Smith and Carston R. Wagner Title: Improving the Metabolic Stability of an Anti-Dengue Nucleotide Prodrug Abstract: The World Health Organization has designated Dengue Virus (DENV) as a top threat to global health due to the alarming rapid spread worldwide. Given these circumstances, there is an urgent need for the first clinically-approved dengue antiviral. The progression of dengue antivirals into the clinic have in part been limited by the lack of nucleotide prodrugs (ProTides) with broad tissue distribution. Current ProTide technologies are liver-targeted, so they have limited efficacy against viruses with broad tissue tropisms, such as DENV. To address this unmet need, our lab has designed and synthesized UMN1003, a novel Anchimerically Histidine triad nucleotide binding protein-1 (HINT1) Activatable (AHA) ProTide. AHA ProTides possesses the unique ability to initially undergo chemical activation instead of carboxylesterase-1 activation. So, due its sole dependence on HINT1 for activation, an enzyme that is ubiquitously expressed in all cell lines, we hypothesize that AHA ProTides will have increased tissue distribution compared to liver-targeted ProTide technologies. However, UMN1003 was recently found to contain poor metabolic stability. Thus, the work presented here aims to directly address the deficiencies of UMN1003 by synthesizing second-generation AHA ProTides with improved metabolic stability. Analogs were evaluated for metabolic stability using mouse liver S9 fraction, and quantified using tandem mass spectroscopy. The antiviral activity of these compounds were initially screened using a BHK-21 DENV-2 replicon reporter, and active compounds were further evaluated for broad spectrum activity using an mCherry DENV reporter in Vero cells. Upon the successful completion of this work, our expected outcome is the identification of an AHA ProTide(s) with improved metabolic stability, broad spectrum activity, and most importantly efficacy in dengue disease-relevant cell lines. |
Author: Jake Schmitt Non-Presenting Authors: Irina Zhilinskaya, Niels Guldager, Gladis Sanchez, Srujana Mohanty, Yutong Liu, Gustavo Blanco, Gunda I. Georg Title: Small-Molecule Inhibitors of Sperm-Specific Ion Channels for Nonhormonal Male Contraceptive Development Abstract: There is a current trend toward smaller families worldwide. With over 45% of all pregnancies globally unintended, there is an urgent need for the development of novel contraceptives. The lack of a reversible, FDA-approved, nonhormonal male contraceptive represents a critical gap in therapeutic innovation. The sperm-specific ion channels CatSper and SLO3 are crucial regulators of hyperactivated motility, which is required for fertilization of the ovum. The restricted expression of these ion channels in sperm offers a selective and non-systemic non-hormonal male contraceptive target. Furthermore, they are genetically validated male contraceptive targets. We report the first ligand-based medicinal chemistry campaign from our initial high-throughput screening hit, 7a. Our initial 7a analogs yielded selective SLO3 inhibitors but had undesirable ADMET properties. Through rational scaffold design and amide-isosteric replacement, we defined clear electronic and steric trends that favorably modulate ADMET properties while developing a dual inhibitor of CatSper and SLO3. Deconjugation of the core and urea modifications emerged as drivers of potency and improved AMDET properties. Functional sperm assays confirm that the analogs can potently suppress CatSper- and SLO3-mediated hyperactivated motility. Alongside our medicinal chemistry efforts, we are employing protein-ligand co-folding models to transition to a structure-based medicinal chemistry campaign. This will enable accelerated iterations of the medicinal chemistry iterative cycle. Collectively, this work establishes a foundational SAR framework for the development of dual CatSper/SLO3 sperm-specific ion channel inhibitors toward the discovery of a nonhormonal male contraceptive. |
Author: Jacob Cowley Non-Presenting Authors: Andrew Riley Title: Isolation and synthesis of alkaloids from Heimia salicifolia Abstract: Heimia salicifolia is a plant with a long history as a folk medicine used by native communities in Central America and Mexico. It has many reported uses including as an anti-inflammatory and antisyphillitic but has recently gained more interest due to its reported psychoactive effects. These effects are controversial and poorly understood, and to date no studies have been undertaken to understand the mechanism of action. As a medicinal chemistry laboratory, we are interested in elucidating the activity of the alkaloids in this plant and exploring their potential usefulness as CNS active drugs. We have explored both the synthesis and isolation of these alkaloids from dried plant material and are awaiting results from the Psychoactive Drug Screening Program (PDSP). These results will hopefully identify one or more targets that could become the focus of a future SAR study. |
Author: Kelsey Holdaway Non-Presenting Authors: Erik B. Faber, Naresh Gantasala, Gunda I. Georg Title: Covalent-Allosteric Inhibitors of Cyclin-Dependent Kinase 2 (CDK2) Abstract: In ovarian and breast cancers, cyclin-dependent kinase 2 (CDK2) is hyperactivated, and genetic ablation studies have shown that CDK2 loss suppresses tumor growth, validating it as a therapeutic target. No highly selective CDK2 inhibitor has advanced clinically, largely due to the challenge of achieving kinase selectivity. Our lab developed potent, selective allosteric CDK2 inhibitors with single-digit nM affinities. Biochemical studies revealed negative cooperativity with cyclin binding, leading to reduced inhibition at high cyclin concentrations. |
Author: Jerrett Holdaway Non-Presenting Authors: Lokesh Saini, Raven Coil-Otto, Pablo E. Visconti, Gunda I. Georg Title: Optimization of a Selective TSSK1/2 Prodrug Degrader for Non-Hormonal Male Contraception Abstract: TSSK1/2 are for spermatogenesis, as male knockout mice are viable but infertile, confirming these kinases as compelling targets for non-hormonal male contraception. Starting from a non-selective ATP-competitive inhibitor, we synthesized iterative series of TSSK1/2 degraders. A stable HiBiT-tagged TSSK1 CHO-K1 cell line enabled quantitation of degradation, and flexible-linker analogues allowed optimization of linker length, affording TSSK1 DC50 values of 10 nM. Incubation of CD1 mouse sperm with degrader 5.4 resulted in 80% loss of TSSK2 by Western blot, translating into pronounced functional deficits with motility reduced >97% and in vitro fertilization abolished. Early degraders exhibited poor metabolic stability in liver microsomes, prompting development of second-generation analogues employing rigid linkers and alternative E3 ligase attachment geometries to refine ternary complex formation. These efforts produced compound 5.16, a potent degrader with DC50 of 8 nM and high cellular tolerability. Introduction of defined stereochemistry and heteroatoms further improved selectivity and stability, producing the morpholine-linked lead 5.34 with similar potency, cytotoxic IC50 >10 μM, markedly extended microsomal half-life, and no kinase inhibition exceeding 40% across a profiling panel. Despite these gains, low solubility in simulated intestinal fluids suggested limited oral absorption. To address this limitation, a tert-butyl ester prodrug, 5.34P, was prepared to enhance solubility and bioavailability. The prodrug increased solubility by >50-fold, remained non-toxic in HepG2 cells, and was rapidly converted to the active degrader in both human and mouse hepatocytes, with most turnover occurring within 15 minutes. Collectively, these studies describe progression from inhibitor to potent selective degrader and soluble prodrug suitable for in vivo evaluation; pharmacokinetic and in vivo efficacy studies are underway to assess systemic exposure and contraceptive activity. |
Author: Bo Zhou Non-Presenting Authors: Leticia Do Amaral, Emily K. Bremers, Reagan S. Haney, Emilio F. Merino, Yuexin Li, Mairi Buchanan, Delphine Baud, Steve Brand, Marcus C. S. Lee, Jane X. Kelly, Max Totrov, Maria B. Cassera, Paul R. Carlier* Title: Pharmacokinetics, in vivo efficacy, phenotyping, and safety pharmacology of the irresistible antimalarial PRC1910 Abstract: In our search to develop new resistance-breaking antimalarials related to the β-carboline 3-carboxamides (e.g. PRC1584), we employed a scaffold-hopping strategy. Eventually we successfully identified a second-generation chemotype: 1-alkyl-imidazo[4,5-c]pyridine-4-aryl-6-carboxamides. After extensive SAR studies, we identified PRC1910 as having superior Plasmodium falciparum growth inhibition potency and excellent in vitro ADME-Tox characteristics. To date, this and related compounds have evaded all attempts at in vitro resistance selection, thus classifying them as “irresistible.” Resistome-screening of PRC1910 against parasites carrying >30 different resistance mutations, on two different genetic backgrounds, also gave no outgrowth. Phenotyping studies in vitro indicate several favorable characteristics, including fast parasite clearance time, killing of early-stage rings with only an 8 h exposure, and ability to kill dihydroartemisin-induced dormant forms of the parasite P. falciparum. PRC1910 has superior PK performance relative to PRC1584, and cured P. yoelii-infected mice in the standard Peter’s test (4 x 40 mg/kg/d, PO) out to 28 days. A large single dose (160 mg/kg, PO) also cured mice out to 28 days. Since the antimalarial target of PRC1910 remains unknown, we prepared an analog of the compound bearing a photoaffinity group and a “click-able tag” to enable chemoproteomic target ID studies. We will also report safety pharmacology data to identify possible off-targets in human. |
Author: Margaret Hill Non-Presenting Authors: Giridhar Chandrasekharan, Diandra Taylor Vaval, and Nancy Freitag Title: A Self-Sensing Peptide Circuit in Listeria monocytogenes Links Glycerol Metabolism to a Novel Bacteriocin Abstract: Listeria monocytogenes (Lm) is a saprophytic bacterium that persists in the environment but becomes an invasive, potentially fatal pathogen when ingested by humans, particularly those who are pregnant or immunocompromised. After inducing its uptake by intestinal epithelial cells, Lm is sequestered within a vacuole before mediating its escape into the cytosol where it can replicate and spread to adjacent host cells. A peptide pheromone, pPplA, is required for efficient vacuolar escape and intracellular growth; furthermore, its deletion markedly reduces virulence in a mouse model of infection. RNA-seq analysis of the ΔpplA mutant revealed the significant dysregulation of genes involved in carbon metabolism and iron transport, including the strong downregulation of the gol operon, which encodes components of a phosphoenolpyruvate (PEP)-dependent glycerol phosphotransferase system. Annotation of this operon by BAGEL4 revealed the inclusion of a gene encoding a pediocin-like immunity protein (IP), which was confirmed to be essential by a temperature-sensitive insertional inactivation. Genome mining further identified a 62-amino acid toxin resembling lactococcin 972, a class II bacteriocin (ribosomally synthesized but not post-translationally modified). The generation of toxin-antitoxin knockout mutants validated the lactococcin-like toxin and pediocin-like IP as a pair. Ongoing work aims to complement these knockout mutants with an IPTG-inducible toxin construct to verify its activity in the absence of its cognate IP. |
Author: Soumajit Gayen Non-Presenting Authors: Lakmal Rozumalski, Pratip K. Dutta, Pete G. Ledesma, Joshua Hassing, Freddys F. Rodriguez, Abhishek Kulkarni, Bryan Magana, Jigar P. Sethiya, Nusha Mikolchak and Carston R. Wagner* Title: HINTabodies: De Novo Catalytic Antibody Mimics for Integrated Tumor Biomarker Detection, Targeted Pro-drug activation and Therapy Abstract: Antibody Drug Conjugates and Antibody-enzyme conjugates have garnered significant interest in developing novel therapeutic approaches over the last few years. The utility of antibody-enzyme conjugates has been limited owing to their low catalytic activity, immunogenicity, and limited engineering strategies. Antibody drug conjugates have proven to be highly effective therapeutic agents, although their size and complex manufacturing protocol have presented challenges. We envisioned that these challenges might be addressed by using a human enzyme as a scaffold, functionalized with targeting ligands. The Wagner Lab has extensively studied Histidine Triad Nucleotide Binding Proteins (HINTs), a ubiquitous superfamily of enzymes involved in diverse biochemical processes and easily expressed in bacteria. These enzymes exist as highly stable homodimers and are primarily known to catalyze the hydrolysis of purine phosphoramidates and acyl-adenylates. Of the members of the family of enzymes, hHINT1 (Human Histidine Triad Nucleotide Binding Protein 1) is the most well-studied. HINT1 is a highly stable homodimer (monomer MW=14 kDa) with highly flexible N-termini that, as the homodimer, are oriented 180 ° from each other. We have found that appending ligands to hHINT1 does not compromise its catalytic activity or ability to deliver conjugated small molecules, while resulting in bivalent binding to cell surfaces. This enables it to act as a bivalent catalytic antibody mimic, which can be applied to in vitro tumor bio-marker detection, followed by in vivo targeted pro-drug activation and ultimately drug-delivery. Results from ongoing in vitro characterization and targeted cytotoxicity studies will be presented. |
Author: Richard Foster Non-Presenting Authors: Sam Feldstein, Kate Rahbari, and Michael Federle Title: Investigating the Effects of Quorum Sensing in Streptococcus pyogenes on Macrophage Viability Abstract: Streptococcus pyogenes (Strep A) is a Gram-positive human restricted pathogen that is known to cause over 600 million infections annually. Strep A’s ability to quorum sense (QS) lends to its ability to coordinate microbial behavior and gene expression. Using the Rgg2/Rgg3 QS system, Strep A can suppress proinflammatory responses of the innate immune system as seen with a decreased NF-kB activity and decreased nitrile and cytokine production in macrophages. Although the Rgg2/Rgg3 QS system was shown to broadly suppress inflammatory transcriptional pathways during infection, phosphoproteomic data showed that traditional inflammatory pathways (MAPK, NF-kB) were not differentially phosphorylated, indicating that the QS system implements alternative mechanisms for suppression. Current work aims to elucidate the specific mechanisms Strep A employs to suppress an immune response. By understanding the molecular mechanisms of how bacterial pathogens cause disease, it is our hope to develop non-antibiotic therapeutics to treat infections. |
Author: Leonardo Lugo Non-Presenting Authors: Lisa E. Rusali, Ana M. Lopez-Hernandez, Benjamin H. Clark, Adam Shaibat, Andrea Cippitelli, Andrew P. Riley Title: Development Of Biaryl Aristoquinoline Analogues to Identify Potent and Selective Inhibitors Of α3β4 For Cocaine Involved Substance Use Disorder Abstract: Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels involved in diseases and disorders of the peripheral and central nervous systems (CNS). The ⍺3β4 nAChR subtype is implicated in the drug-seeking behavior of psychostimulant-related substance use disorder (pSUD), which has no recent FDA-approved treatments. Previous reports from our group have identified a natural product isolated from Aristotelia chilensis, aristoquinoline (ARQ), that inhibits α3β4 and attenuates cocaine-seeking behavior in a rodent model of relapse. By substituting the quinoline ring of ARQ for hetero and non-hetero arenes, we identified compounds with increased potency and selectivity with respect to other nAChRs. To further investigate the role of the arene region, we began to explore a series of analogues containing biaryl systems. By employing a nitrogen scan to biaryl analogues, we can develop a small library of analogues, and can further explore torsional strain by incorporating methyl substituents. From this, we have identified biaryl compounds with moderate to high potency at ⍺3β4, which have the potential to become preclinical candidates. |
Author: Xuankun Chen Non-Presenting Authors: Hua Tang, Peijing Jia, Yaxian Zhou, Deqin Cai, Junzhuo Liao, Zhen Zhang, and Weiping Tang Title: Catalytic Small Molecule Lysosome Targeting Chimeras (LYTACs) that Recruit Asialoglycoprotein Receptors (ASGPR) Abstract: Targeted protein degradation (TPD) has emerged as a highly promising alternative to traditional inhibition-based therapeutic strategies. Lysosome-targeting chimeras (LYTACs) represent an attractive platform for degrading extracellular disease-associated proteins. However, most reported LYTACs are large molecules that function in a stoichiometric manner. The development of small-molecule LYTACs capable of operating through a catalytic mechanism would be highly desirable. |
Author: Raven Coil-Otto Non-Presenting Authors: Jerrett A. Holdaway, Saman Nayyab, Pablo E. Visconti, Gunda I. Georg Title: Development of Selective TSSK Inhibitors/Degraders for Non-Hormonal, Male Contraception Abstract: Testis-specific serine/threonine kinases (TSSKs) are essential for spermatogenesis, particularly spermiogenesis. Knockout mouse models of TSSK1, 2, 3, and 6 show that the mice are healthy and that male mice are infertile. Human triallelic and single-nucleotide polymorphisms in TSSKs 6 and 2 result in spermatogenic impairment, further validating these targets. These findings make TSSKs prime targets for non-hormonal male contraception. Of particular interest is that transcription and translation are silenced during spermiogenesis, making degraders an attractive area of research. Starting with a previously reported, non-selective ATP-site inhibitor (TSSK1/2 IC50 = 0.86 nM/66 nM), we have designed and synthesized a series of TSSK1/2 degraders. Preliminary degraders of TSSK2 were identified in human and mouse sperm, but they exhibited poor solubility and permeability. Rigidification of the linker, as well as the addition of a prodrug handle off the glutarimide nitrogen, rescued these properties. Preliminary selectivity profiling of 24 kinases highlighted the improved selectivity profile of these degraders. To identify novel, selective TSSK inhibitors, we performed four DNA-Encoded-Library Screens that yielded ~10 potential binders of TSSK1/2, one of which showed picomolar inhibitory activity against TSSK1 in a functional assay. Despite being an ATP-site inhibitor, this compound demonstrated remarkable kinome selectivity. It also possessed a vector (identified by QSAR analysis) that modulated isoform selectivity and potentially potency. Despite its high potency, this compound has poor permeability, is subject to efflux, and exhibits poor metabolic stability. Truncation of the DNA-tag vector rescued permeability/efflux; however, metabolic stability remains an issue. Liver microsome metabolite ID will be performed on our lead compounds to identify their metabolites in CD1 mouse S9 microsomal fractions via MS/MS analysis. |
Author: Ehfazul Haque Non-Presenting Authors: Rui Shi, Gunda I. Georg Title: DISCOVERY OF SECOND GENERATION RAR ALPHA/GAMMA DUAL INHIBITORS AS MALE CONTRACEPTIVE AGENTS Abstract: Women have historically borne the contraceptive burden because of limited reversible options for men. The available options, withdrawal and condoms, have significant failure rates (22% and 12%, respectively). Thus, non-hormonal male contraceptive agents have emerged as a promising avenue to yield safe and efficacious male birth control options. Retinoic Acid Receptor α (RARα) and RARγ are nuclear receptors essential for spermatogenesis and validated male contraceptive targets. In rats fed a vitamin A-deficient diet, the precursor of the natural ligand All-Trans Retinoic Acid (ATRA), reversible sterility was observed. Additionally, Rara/Rarg double-knockout mice were found to potentiate the azoospermia observed in single-knockout models. Oral administration of BMS-189453, a pan-RAR antagonist, reversibly inhibited spermatogenesis. However, this compound was later identified as a potent RARα/β agonist. Subsequent efforts in our group have focused on identifying RARα/γ dual antagonists with a cleaner off-target profile. Preliminary structure-based drug design has yielded dual-selective leads such as SR210721D (IC50: RARα, β, γ: 0.37 nM, >100 nM, 1.7 nM). Although the ADMET profile was promising, the compound failed to inhibit spermatogenesis in CD1 mice after oral administration at 10 mg/kg/day for 28 days. This may be due to the compound's high metabolic clearance and suboptimal testicular uptake. To address these issues, new compounds have been pursued that incorporate design elements from BMS-189453 and YCT-529, our current RARα-selective clinical candidate, which both displayed superior target tissue distribution and inhibition of spermatogenesis. Several dual-selective inhibitors have been identified in a cellular reporter assay, such as EH-076 (IC50: RARα, β, γ: 0.18 nM, >100 nM, 1.4 nM). Preliminary physicochemical and ADMET evaluations of these compounds are underway to assess their suitability as second-generation leads for preclinical studies. |
Author: Maryam Nazari Non-Presenting Authors: Gunda I. Georg Title: Discovery of Anti-Cancer Agents via Cyclin-Dependent Kinase 2 Bivalent Inhibitors Abstract: Cyclin-dependent kinase 2 (CDK2) functions as a controller of the cell cycle through regulatory and transcriptional roles during the G1 and S phases. CDK2 dysregulated activity contributes to the pathology of ovarian, breast, and colorectal cancers.1 Additionally, an increased level of an endogenous CDK2 activator, cyclin E1, has been documented in ovarian and breast cancers, resulting in CDK2 hyperactivity.2 Several selective CDK2 inhibitors have advanced into clinical trials targeting the highly conserved ATP pocket that can lead to off-target toxicities.2 The Georg group has developed selective CDK2 inhibitors targeting a unique allosteric pocket to address this issue.3 However, these inhibitors showed negative cooperativity with cyclin, resulting in decreased affinity at increased cyclin concentrations in the assay.3 We hypothesized that a bivalent molecule binding to both ATP and allosteric sites simultaneously would exhibit stable activity at high cyclin concentrations and may have a longer residence time relative to cyclin. We computationally designed and synthesized multiple bivalent scaffolds comprising the allosteric site binders established by our group and diverse ATP site binders. Cytotoxicity was evaluated in a cyclin E1 amplified ovarian cancer cell line, OVCAR3, using the Cell Titer Glo assay. Additionally, ADP-Glo and p-Cl-ANS assays were performed to confirm binding affinities to the ATP pocket and the allosteric site, respectively. Some compounds maintained CDK2 inhibitory activity, despite increased cyclin concentrations in the assay, and showed improved affinities and residence times. |
Author: Noha Taher Non-Presenting Authors: Ehfazul Haque, Rui Shi, Jiaheng Fan, Martin M. Matzuk, Gunda I. Georg Title: Development of Second-generation RARα Antagonists for Non-hormonal Male Contraception and Industrial Synthesis Route for YCT-529 Abstract: Even with the current available contraceptive methods, nearly half of all pregnancies worldwide are unintended. In the United States, the taxpayer burden from unplanned pregnancies is between $5.5 billion and $21 billion per year. An active metabolite of dietary vitamin A, all-trans retinoic acid (ATRA), binds to retinoic acid receptors (RAR) in germ cells and activates genes responsible for several phases of sperm differentiation. Our lab has characterized the first orally bioavailable reversible RARα selective antagonist, YCT-529. It selectively targets RARα by engaging in hydrogen bonding to a unique serine 232 present only in RARα. It induces antagonism due to a bulky group substituent that prevents conformational activation of RARα. With its advancement in Phase 1a/2b clinical trials, its kilogram scale synthesis suffers from the expensive and challenging removal of iridium and palladium catalysts. A new synthesis route that relies on a modified Kulinkovich 1,4-diketone synthesis using ZnCl2·t-BuOH·Et2NR complex successfully improved the efficiency and cost of production (33% in 4 steps). Density functional theory of a model Kulinkovich reaction gave insights into the optimal halo-ketone to be used in the synthesis. A DNA-Encoded Library (DEL) screen with 6 billion compounds was performed by the Matzuk group for RARα to diversify our current ligand space. After resynthesis of the binders, only one compound had potent and selective RARα inhibition (6.7 nM) in our cellular-based assay. With this novel structural motif, structure-activity relationship studies are underway to increase the potency, selectivity, and drug-like properties that could advance to ADMET studies. |
Author: Tsering Tashi Non-Presenting Authors: Sruthi Mohan, Leticia Do Amaral, Emily K. Bremers, Reagan S. Haney, Emilio F. Merino, Max Totrov, Maria B. Cassera, Paul R. Carlier Title: Optimization of novel indole- & 7-azaindole-3-carboxamide antimalarials Abstract: PRC1584, a β-carboline amide, showed high P. falciparum growth inhibition potency (EC50 = 108 ± 7 nM) and achieved oral efficacy in P. berghei model of murine malaria at 40 mg/kg/d X 4 d. Importantly, it failed to yield resistant parasites after repeated attempts at in vitro selection. Scaffold hopping from PRC1584 led to novel indole PRC2391, albeit with biphasic growth inhibition (EC50 = 22 ± 2 nM, 301 ± 168 nM); such biphasic activity is not desirable. To avoid such behavior, we explored a number of structural modifications. In particular, replacement of the 5-bromo substituent with benzylamine (e.g., PRC2520) and replacement of the indole core with a 7-azaindole scaffold (PRC2661) led to reasonable cellular potency (EC50 = 157 ± 12 nM & 35.1 ± 15.9 nM respectively) and restored monophasic growth inhibition. In this presentation I will describe our work within this scaffold to reach the ultimate goal of a single-digit nM cellular potency and single-dose efficacy in mice (≤ 100 mg/kg). |
Author: Mackenzie R. Ringer Non-Presenting Authors: Bo Zhou, Emily K. Bremers, Reagan S. Haney, Leticia S. Do Amaral, Maxim Totrov, Maria B. Cassera, Paul R. Carlier Title: Identification of 2,5-diaryl-1H-benzo[d]imidazole-7-carboxamides as Antimalarials Abstract: Malaria, a disease caused by the parasite P. falciparum, continues to be a global health challenge, with over 600,000 fatalities and 200 million cases occurring annually. Despite significant progress in developing treatments, drug resistance remains a critical issue and the need for new antimalarials remains prevalent. Previous work by our group investigated PRC1584 (1), a N-aminoalkyl-β-carboline-3-carboxamide which was derived from analogous hits within the Malaria Box. PRC1584 exhibited good in vitro potency (EC50 = 108 ± 7 nM) against the multi-drug-resistant strain of P. falciparum and was found to be orally efficacious in a P. berghei-infection mouse model of malaria. Following this work, several iterations of scaffold-hopping were employed to identify new chemotypes for SAR exploration. This effort led to the identification of the imidazo[4,5-c]pyridine-6-carboxamide series (2), which demonstrated SAR trends consistent with those observed for series 1, suggesting that these scaffolds have a shared biological target. Attempts to elucidate this target through resistance selection experiments were unsuccessful, as both series proved refractory to resistance selection. Subsequent scaffold hopping led to the discovery of a new chemotype, 2,5-diaryl-1H-benzo[d]imidazole-7-carboxamide (3), as an early hit. Good potency has been achieved in this series (EC50 = 37.6 ± 4.3 nM), but challenges requiring further development will be presented. |
Author: Isabella Jacobsen Non-Presenting Authors: Rui Shi , Cole Scholtz , William C. Pomerantz , Gunda I. Georg Title: Harnessing tissue-restricted E3 ligase scaffolding protein MAGEA11 for cancer-specific protein degradation Abstract: Proteolysis targeting chimeras (PROTACs) are an emerging therapeutic modality that induces protein degradation by recruiting E3 ligases. PROTACs offer advantages over traditional inhibitors, such as catalytic dosing and targeting of undruggable proteins. Most reported PROTACs recruit ubiquitously expressed E3 ligases, such as cereblon and von Hippel-Lindau. Of the 600+ unexploited E3 ligases, recruiting those with tissue-restricted expression is attractive for increasing the specificity of PROTACs. To this end, tissue-specific E3 ligases or E3 ligase-associated proteins that can be recruited for targeted protein degradation need to be identified. |
Author: Juliet Jelu Non-Presenting Authors: Terry W. Moore Title: Development of Hydrocarbon Stapled Peptide Inhibitors Targeting Estrogen Receptor-Positive Breast Cancer Abstract: As of 2024, breast cancer is the most diagnosed form of cancer for women in the United States, accounting for more than 310,000 new cancer cases, and resulting in over 42,000 deaths in 2023. Among the four |
Author: Jacob Lee Non-Presenting Authors: Dr. Barbara Adaikpoh Title: Investigating Plant Hormone Activation of Antifungal Biosynthetic Gene Clusters Abstract: Investigating Plant Hormone Activation of Antifungal Biosynthetic Gene Clusters |
Author: Trevor Dean Non-Presenting Authors: Alyah Ziyad, Dorota Klepacki , Nora Vázquez-Laslop , Alexander Mankin , Terry Moore Title: Evaluating the Ribosome Binding Activity of the Natural Product Antimicrobial Peptide Pdi1 Abstract: The rapid growth of antimicrobial resistance is a pressing public health concern that |
Author: Michael Garcia-Mares Non-Presenting Authors: Sarah E. Preston, Erica N. Heisdorffer, Laura E. Dean, Hans-Joachim Lehmler, Jon A. Doorn Title: Human-relevant PCB52 metabolites trigger mitochondria-dependent bioenergetic collapse in glia Abstract: Background and Purpose: Lower-chlorinated polychlorinated biphenyls (LC-PCBs) are persistent environmental toxicants associated with developmental neurotoxicity, with rising concern due to inhalation exposure. A major gap is how glial bioenergetics shapes PCB-driven injury, particularly for human-relevant PCB metabolites. Because astrocytes buffer neuronal metabolism, mitochondrial disruption in astrocytes may represent an early, upstream event in PCB neurotoxicity. We investigated PCB-52 and major human-relevant hydroxylated and sulfated metabolites in differentiated C6 astroglioma cells to define an astrocyte-like, metabolism-relevant vulnerability profile. |
Author: Kostana Ligori Non-Presenting Authors: Nusha Mikolchak, Carston R. Wagner Title: Privileges and Drawbacks of Guanosine Scaffolds in Photocatalytic Proximity Labelling Probes Abstract: Intracellular photocatalytic proximity labelling presents an avenue for dissection of protein interactions in a spatiotemporal manner without disrupting biological processes. To ensure such results, careful probe design is crucial to ensure biologically relevant conformations and interactions are not affected upon binding and subsequent labelling. Our lab has adopted intracellular photocatalytic proximity labelling to study Histidine Triad Binding Nucleotide 1 (HINT1) and its role in Mu Opioid Receptor (MOR) – N-Methyl-D-Aspartic Acid Receptor (NMDAR) crosstalk. We have previously demonstrated that HINT1 inhibitors provide selective modulation of the crosstalk in vivo, eliciting a range of pharmacological responses that are not recapitulated in binding affinity trends. Photocatalytic proximity labelling would allow for the study of HINT1 interactions upon inhibition to deduce changes in protein partners that determine pharmacological outcomes. Our current probe design features riboflavin tetraacetate (RFTA) as a photocatalyst, attached to our inhibitors via an alkyl triazole linker. As a nucleoside binding protein, HINT1 inhibitors contain modified and endogenous nucleoside structures that may pose synthetic challenges. The work presented in this poster focuses on taking advantage of controlled labelling due to photocatalyst quenching abilities of guanosine and navigating the peculiarities of guanosine chemistry, notably intermolecular interactions such as G-G base pair stacking and other intramolecular interactions. |
Author: Shenell F. Brown Non-Presenting Authors: Luke Harding1, Valentina Z. Petukhova1, Brenna Flowers2, Abigail Rullo2, Sammy Y. Aboagye3, Kevin Lemus3, Francesco Angelucci4, David L. Williams3, Irida Kastrati2, Pavel A. Petukhov1 Title: Development of non-covalent thioredoxin reductase inhibitors to treat triple-negative breast cancer Abstract: Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer that lacks targeted therapeutics. TNBC is responsible for 50% of breast cancer cases in women who are 40 years or younger and have the BRCA gene mutation. Certain ethnic groups are, unfortunately, twice as likely to be diagnosed with TNBC. Current non-selective chemotherapies, as well as targeted therapies such as PARP inhibitors and antibody-drug conjugates, improve patient outcomes but remain markedly limited in efficacy, as evidenced by 5-year survival rates of only 12-15% and median overall survival of 1.5-2 years. We have demonstrated that TNBC is susceptible to inhibition of thioredoxin reductases (TXNRD) mediated by the inability of cells to synthesize deoxyribonucleotides. My project focuses on developing non-covalent inhibitors that bind the allosteric regulatory doorstop pocket of TXNRD. The goal is to stop proliferation, induce G1 cell cycle arrest, and promote cell death, likely by impairing ribonucleotide reductase function in TNBC, while maintaining selective toxicity against TNBC. Using the Craig plot approach, I explored how the electronic and lipophilic properties of the substituents in ring C of the novel benzodiazepine-based TXNRD inhibitors (TXNRD(i)s) developed in our group affect their activity in assays with recombinant TXNRD enzymes and cultured cells. The effect of the common protecting group, p-methoxybenzyl (PMB), on inhibitor potency was also investigated. The novel putative TXNRD(i)s were tested for inhibition of recombinant TXNRD enzymes and for mechanism-based cytotoxicity in cellular models of TNBC, and prioritized for testing in in vivo TNBC xenograft models in mice. The outcomes of these studies will be presented at the meeting. |
Author: Kusha Sameeha Malpath Non-Presenting Authors: Emily Bremers, Leticia Do Amaral, Maria B. Cassera, Paul R. Carlier Title: Leaping Scaffolds: From imidazopyridines to biphenyls Design, synthesis and in vitro potencies of novel antimalarial chemotypes Abstract: The emergence of multidrug-resistant Plasmodium falciparum necessitates the expansion of the antimalarial drug pipeline with novel and potent chemotypes. Our previous work identified a novel imidazo[4,5-c]pyridine-6-carboxamide antimalarial PRC 1910 with an EC5072h value of 55 ± 15 nM. This compound is unaffected by over 40 different resistance mutations in P. falciparum and cures P. yoelii-infected mice out to 28 days at an oral dosing of 4 x 60 mg/kg/day or 1 x 160 mg/kg. We utilize the imidazopyridine framework as a template to design and synthesize two novel 1,1’-biphenyl based scaffolds 2 and 3 via rational structural modifications and scaffold-hopping. In this poster, we will describe the synthetic evolution of the two distinct scaffolds and focus on how alterations to the core structure impact in vitro potencies and physicochemical profiles. |
Author: An T. Trinh Non-Presenting Authors: Mark D. Ericson, Katie Henning, Marc A. Giulianoti, Clemencia Pinilla, Radleigh G. Santos, Carrie Haskell-Luevano Title: Design of a Peptide Combinatorial Library to Screen for Pharmacological Activity at the Melanocortin-3 Receptor (MC3R) Abstract: The melanocortin family consists of five G protein-coupled receptors (GPCRs) known as the melanocortin 1–5 receptors (MC1–5Rs). Two melanocortin receptors expressed in the central nervous system, MC3R and MC4R, are involved in energy homeostasis, feeding behaviors, and body weight. Peptides including the adrenocorticotropin hormone (ACTH) and α-melanocyte-stimulating hormone (α-MSH) are endogenous agonists of the melanocortin receptors, while the agouti protein (ASP) and agouti-related protein (AGRP) are naturally occurring antagonists. To discover novel MC3R ligands with > 500-fold selectivity, a sizing library of peptides was designed and synthesized by Fmoc solid-phase peptide synthesis in teabags, containing ≈ 1014 (100 trillion) compounds of various lengths. The library was characterized by LC-MS and screened for pharmacological activity at MC3R and several other melanocortin receptors. A subsequent mixture-based positional scan based on an optimal peptide length selected from this library will potentially identify novel and selective MC3R ligands. |
Author: Emmanuel Bonsu Non-Presenting Authors: David Martin Title: Synthesis of neuroprotective limonoids and analogs Abstract: The importance of investigating neuroprotective natural products has increased over the years as the scourge of neurodegenerative diseases (NDs) is on the rise. The ubiquity of limonoids among citrus fruits and their promising activity against glutamate-induced neurodegenerative processes, make them preferred candidates for treating some types of neurodegenerative diseases. Previous research established the neuroprotective activity of a subset of limonoids derived from traditional medicines, namely limonin, obacunone, calodendrolide, and fraxinellone. Several analogs of these limonoids have been synthesized in the Martin lab and their biological activity is being tested. New insights into their potency and mechanism of action will be discussed. |
Author: Kevin A. Kunz Non-Presenting Authors: Leticia Do Amaral, Yuexin Li, Dejan Nikolic, Emilio F. Merino, Jane X. Kelly, Max Totrov, Maria B. Cassera, Paul R. Carlier Title: Triazine-core MMV007808 derivatives as new DHODH-inhibiting antimalarials Abstract: Malaria remains a major global health challenge, with the World Health Organization (WHO) reporting over 250 million cases and approximately 600,000 deaths in 2023. The spread of resistance to artemisinin-based combination therapies shows the urgent need for novel drug targets and new classes of antimalarials. |
Author: Mark C. Kelley Non-Presenting Authors: Emma R. Smith, Daniel A. Harki* Title: Development of a Direct-to-Biology (D2B) Platform for the Accelerated Discovery of Targeted Protein Degraders Abstract: Direct-to-Biology (D2B) is an emerging drug discovery strategy, enabled by the advent of small scale, parallel synthesis and high-throughput assays to rapidly generate and screen novel chemical libraries. D2B approaches are particularly beneficial for developing Proteolysis-Targeting-Chimeras (PROTACs). PROTACs are bifunctional molecules that form ternary complexes between a target protein and an E3-ligase to induce targeted protein degradation. Due to the requirement of inducing proximity in a spatial orientation that yields a ternary protein complex capable of inducing a productive protein degradation event, PROTAC development often requires significant synthesis efforts to optimize linker composition. D2B workflows offer an opportunity to accelerate this process. We have implemented parallel amide coupling chemistry to enable the plate-based synthesis of PROTAC libraries. This is accomplished by coupling protein-targeted ligands that terminate in a carboxylic acid with a library of commercial and novel E3 ubiquitin ligase ligands tethered to a terminal amine using various linker compositions. Subsequent cellular assays using HiBiT technology enables parallel testing of the library for induced protein degradation. We are applying this PROTAC-discovery approach to several targets, including REarranged During Transfection (RET) kinase, which is a Receptor Tyrosine Kinase (RTK) altered in 2.6% of all cancers that has been implicated in tumorigenic signaling. Our efforts to develop and optimize D2B workflows will be presented. |
Author: Zhe Wang Non-Presenting Authors: Reinner O. Omondi, Krishna C. Gurajala, Luke N. Erber Title: Elevated Glucose Increases Genomic Instability by Generating DNA-Protein Crosslinks Abstract: Crosslinking between DNA and protein results in a bulky DNA lesion that distorts the DNA helix and obstructs essential DNA protein interactions necessary for DNA replication, transcription, repair, recombination, and chromatin remodeling. DNA-protein crosslinks (DPCs) can be induced by exposure to physical and chemical agents. If not repaired, DPCs lead to permanent DNA alterations and toxicity. DPCs formed by endogenous metabolites are elevated in individuals suffering from Ruijs-Aalfs syndrome, a genetic disorder defined by polymorphisms in the SPRTN gene, encoding a protease involved in DPC repair. Patients with Ruijs-Aalfs exhibit genomic instability, premature aging, and develop hepatocellular carcinoma. Given that elevated glucose levels lead to increased formation of electrophilic intermediates including 1,3-bisphosphoglycerate, methylglyoxal, glyoxal, and 3-deoxyglucosone, we hypothesized that glycolysis is an important endogenous source of DPCs. |
Author: Srujana Mohanty Non-Presenting Authors: Jake Schmitt, Yutong Liu, Gladis Sanchez, Gustavo Blanco, and Gunda I Georg Title: Development of Dual CatSper and SLO3 Inhibitors as Non-Hormonal Male Contraceptives Abstract: Male contraceptive options are limited to condoms and vasectomy, both of which have drawbacks, including inconsistent efficacy or invasiveness. A non-hormonal, on-demand, and reversible oral contraceptive is thus highly desirable. CatSper and SLO3, two sperm-specific ion channels, are crucial for sperm capacitation and hyperactivated motility. Genetic knockout of either channel in mice causes infertility, confirming them as contraceptive targets. |
Author: Danielle Quindel Non-Presenting Authors: Carolyn J. Straub, Gisela A. Camacho Hernandez, Simone M. Creed, Andrew P. Riley, Amy Hauck Newman Title: Efforts to Define the Mechanism of Action of Ibogaine Abstract: Ibogaine is a psychoactive indole alkaloid, isolated from the iboga shrub (Tabernanthe iboga), which is used as a traditional medicine and in spiritual rituals in central Africa. In rodents, ibogaine appears to be effective in the treatment of several substance use disorders (SUDs), including opioid use disorder (OUD). Although several receptors and transporters have been proposed as the biological target for ibogaine, including the α3β4 nicotinic acetylcholine receptor (nAChR), serotonin transporter (SERT), dopamine transporter (DAT), and κ opioid receptor (KOR), ibogaine has low micromolar affinity for each of these potential targets. To investigate its mechanism of action (MOA), we synthesized a library of fourteen metabolites of ibogaine and screened them for biological activity across these and other CNS targets. Our data, as well as previous literature results, identified that noribogaine had the greatest affinity for the SERT. Based on these preliminary results, we hypothesize that ibogaine derives its anti-addictive properties via its major metabolite targeting the SERT. To test this hypothesis, we are synthesizing a series of noribogaine analogs and evaluating their biological activity at the SERT. After establishing structure-activity relationships, lead compounds will be evaluated in animal addiction models to elucidate a mechanistic connection between SERT modulation and therapeutic anti-addictive effects. |
Author: Mandisa Timba Non-Presenting Authors: Maxim Svetlov, Clemence Dunand, Nora Vazquez-Laslop, Alexander Mankin Title: The Sequence of the Nascent Protein Impacts Ribosome Rescue by an ARE-ABCF Protein from the Action of Macrolide Antibiotics Abstract: Macrolide antibiotics inhibit bacterial protein synthesis by binding in the ribosomal nascent peptide exit tunnel (NPET), where they interfere with peptide elongation. Rather than uniformly blocking translation, macrolides induce context-specific ribosome stalling, arresting translation only at particular nascent peptide motifs. These sequence-dependent arrest events create selective translational pauses across the transcriptome and represent an important determinant of macrolide antibacterial activity. Understanding how interactions between the antibiotic, the ribosome, and the nascent peptide influence translational arrest is therefore important for the development of improved macrolide therapeutics. Here, we investigate how sequence-dependent macrolide stalling influences resistance mediated by MsrE, a member of the antibiotic resistance ATP-binding cassette of subtype F (ARE ABCF) family. ARE-ABCF proteins confer resistance through a ribosome protection mechanism in which ATP-dependent binding to the ribosomal E site promotes release of ribosome-bound antibiotics and restores translation (Murina et al., 2018). Structural analysis of the MsrE-ribosome complex revealed that the interdomain linker of the MsrE extends toward the peptidyl-transferase center and into the exit tunnel, suggesting that resistance may occur through displacement of the bound antibiotic (Su et al., 2018). Using ribosome profiling in Escherichia coli treated with the macrolide azithromycin, we identified numerous sequence-specific ribosome arrest sites across the transcriptome. Expression of MsrE rescues many of these stalled ribosomes; however, a subset of arrest sites persists despite the presence of the resistance protein. Biochemical validation confirmed that several macrolide-dependent arrest motifs remain refractory to MsrE-mediated rescue. These persistent stalls overlap with previously characterized macrolide-sensitive motifs but also include newly identified sequence signatures that appear specific to azithromycin. Together, these results indicate that nascent peptide composition within the drug-obstructed exit tunnel modulates the ability of MsrE to restore translation. These findings highlight how antibiotic structure and peptide sequence context jointly influence ribosome stalling and resistance. Defining these sequence-dependent interactions may help guide the development of next-generation macrolides capable of maintaining activity against bacteria carrying ribosome protection determinants. |
Author: Megan J. Jurek Non-Presenting Authors: Angelica R. Ramos, Kyle M. Kremiller, PhD, and Andrew P. Riley, PhD Title: Targeting Nicotinic Acetylcholine Receptors for Neuropathic Pain and Substance Abuse Disorders Abstract: Approximately 1 in 10 adults in the U.S. experience chronic neuropathic pain, which is pain caused by a malfunctioning or diseased nervous system. Current treatments for neuropathic pain are only moderately effective and possess serious side effects, therefore, there is a need for new and safer treatments. Additionally, due to the addictive nature of opioid analgesics, many patients that experience chronic pain are at a higher risk of developing substance abuse disorders when seeking relief. Nicotinic acetylcholine receptors (nAChRs) have been studied for their roles in pain and substance abuse disorders, specifically the α9α10 and α3β4 subtypes, respectively. For the α9α10 nAChR, previous work has shown that antagonism with α-conotoxin inhibitors reduces allodynia and hyperalgesia in rodent models. Despite this promising evidence supporting α9α10 as an analgesic target, current antagonists have poor oral bioavailability, low metabolic stability, and are non-selective. Our group has recently developed a cell line that stably expresses functional α9α10 nAChRs at the cell surface, allowing us to identify and investigate new ligands for this receptor. A drug repurposing screen has been conducted, identifying otilonium bromide as a lead compound and a structure-activity relationship campaign has been implemented. In parallel, AT-1001, a selective partial agonist of the α3β4 nAChR, has been effective in substance abuse rodent models. However, the degree of agonism efficacy of this scaffold in these models have not been investigated. A library of AT-1001 analogues has been evaluated at the α3β4 nAChR, using the published cryo-EM structure as a tool for compound design. |
Author: Ebuka Onyeyilim Non-Presenting Authors: David Martin Title: Synthesis of Thiophene Analogs of Neuroprotective Limonoids Abstract: Limonoids are a class of natural products with the basic scaffold of 4,4,8-trimethyl-17-furanylsteroid. They have been reported to show neuroprotective activity against glutamate-mediated neurotoxicity, but the mechanism of action of limonoid neuroprotection was largely unknown prior to our studies. In the Martin lab, degraded limonoids like calodendrolide, fraxinellone, and isofraxinellone have been synthesized, as well as numerous analogs, while their neuroprotective activity is tested in Prof. Jon Doorn’s lab (UI Pharmaceutical Sciences and Experimental Therapeutics). Replacing the naturally occurring furan group with heterocycles such as thiophene yields analogs with good activity against glutamate excitotoxicity. Synthesis of these compounds and probe molecules to investigate their mechanism of action will be discussed. |
Author: Tsung-Yu Yeh Non-Presenting Authors: Hua Tang, Yaxian Liao, Kazuya Nishibayashi, Milad Rouhimoghadam, Ka Yang, Chunrong Li, Regina Stasser de Gonzalez, Yuan Zhao, Nina J. Hawkins, Justin M. Reitsma, Steven P. Gygi, and Weiping Tang Title: Aryl Aldehyde-anchored Small Molecules Recruit FBXO22 for Targeted Degradation of NSD2 Abstract: Proteolysis-targeting chimeras (PROTACs) can induce the proximity of a protein of interest (POI) and an E3 ubiquitin ligase to trigger poly-ubiquitination, leading to the degradation of the POI by the 26S proteasome. To date, CRBN and VHL are the most widely used E3 ligases in both academia and industry. However, downregulated E3 ligases expression or binding site mutations have been reported, which hamper the efficacy of PROTACs solely recruiting CRBN or VHL. Hence, we are interested in expanding the E3 ligase toolbox. Here, we report the discovery of an aldehyde-anchored PROTAC that covalently engages the E3 ligase FBXO22 to induce degradation of the histone methyltransferase NSD2. Competitive electrophile screening identified a phenyl aldehyde warhead, with SAR studies revealing that degradation is highly sensitive to the steric and electronic environment of the aldehyde moiety. The lead degrader, T9, effectively and selectively induces NSD2 degradation across multiple cancer cell lines. Mechanistic studies using immunoblot and NanoBRET confirmed that degradation is dependent on FBXO22, the ubiquitin-proteasome system, and the neddylation pathway, with mutagenesis identifying Cys326 as the critical residue for covalent engagement. This work establishes a stable covalent ligand for FBXO22, expanding the chemical space of PROTAC design by introducing a readily accessible aldehyde-based E3 ligase ligand with broad potential for protein degradation. |
Author: Thao-Vy T. Nguyen Non-Presenting Authors: Nina J. Hawkins, Deqin Cai, Weiping Tang Title: Peptide-based CRBN Library for Molecular Glue Degraders Abstract: Molecular glue degraders promote interactions between proteins that do not normally associate, enabling targeted protein degradation through E3 ubiquitin ligases such as Cereblon (CRBN). Although computational analyses predict that thousands of proteins are potential CRBN-neosubstrates, only ~40–50 have been experimentally validated, and many molecular glues have been discovered serendipitously. This limited dataset makes rational structure–activity relationship (SAR) development challenging. To efficiently explore new CRBN-binding ligands and novel neosubstrates, we developed a peptide-based library using solid-phase peptide synthesis (SPPS) incorporating a phenyl–glutarimide motif known to engage CRBN. A 44-member library was generated by systematically varying the second amino acid residue. Fluorescence polarization assays identified several compounds that bound CRBN in vitro, but cellular engagement remained limited. To evaluate whether cell permeability was a limiting factor, site-specific N-methylation of glycine residues was performed. Although methylation was successfully achieved under optimized conditions, it did not improve in-cell binding. These findings highlight the complexity of CRBN–peptide interactions and underscore the importance of systematic amino acid–level SAR studies to identify ligands with both strong binding and cellular activity. |
Author: Regina Stasser de Gonzalez Non-Presenting Authors: Yuan Zhao, Xuankun Chen, Weiping Tang Title: Development of LRP1-Targeting Fusion Protein LYTACs Abstract: Lysosome Targeting Chimeras (LYTACs) represent an emerging modality in Targeted Protein Degradation (TPD). These heterobifunctional degraders facilitate the lysosomal degradation of extracellular and transmembrane proteins by simultaneously binding a therapeutic target and a Lysosome Targeting Receptor (LTR). A promising LTR candidate is the Low-density lipoprotein receptor-related protein 1 (LRP1), which is capable of receptor-mediated transcytosis, offering a potential pathway for LYTACs to cross the Blood-Brain Barrier (BBB). Recent work in our laboratory utilized L57, an LRP1-targeting peptide, to develop LYTACs capable of degrading EGFR and PD-L1. However, these initial degraders relied on the complex chemical conjugation of antibodies. To enhance the scalability and versatility of LRP1-targeted degradation, we designed and purified recombinant fusion protein LYTACs. These constructs integrate the L57 peptide with high-affinity small protein binders, such as affibodies or nanobodies, directed toward the protein of interest (POI). This approach simplifies the modular design of LYTACs and expands their therapeutic potential for targeting membrane-associated proteins in oncology and neurology. |
Poster Session 2 |
Author: Angela Nguyen Non-Presenting Authors: Yu-Shiuan Cheng, Ricky Chen, Alison E. Ondrus Title: Ligand-sensitive TMEM97 protein complexes in amyloid beta pathology Abstract: Alzheimer’s disease (AD) is a neurodegenerative disorder with few disease-modifying therapeutic options. Recently, TMEM97, also known as the sigma-2 receptor, has emerged as a promising target for small molecule therapeutics to target AD biology. Existing studies indicate that TMEM97 is a critical component of receptor complexes that facilitate cellular uptake of amyloid beta (Aβ), a neurotoxic peptide whose aggregation and accumulation drive neurodegeneration. However, the molecular composition of TMEM97 receptor complexes remains poorly defined, limiting the development of mechanism-based TMEM97 ligands as drugs for AD. |
Author: Anna Nguyen Non-Presenting Authors: Yu-Shiuan Cheng, Alison Ondrus Title: Small molecule regulation of TSPO structure and function Abstract: The 18 kDa translocator protein (TSPO) is upregulated in a broad spectrum of neurological injuries and neurodegenerative diseases. As a result, small molecule TSPO ligands are first-in-line PET imaging agents for neuroinflammation in the clinic, and select TSPO ligands have shown promise as anti-neuroinflammatory agents. At the cellular level, TSPO is also implicated in processes related to steroidogenesis and porphyrin metabolism, and both cholesterol and protoporphyrin IX (PPIX) are proposed to be endogenous TSPO ligands. However, the mechanistic connections between TSPO protein function, ligand regulation, and neuroinflammation remain undefined. A central unresolved question is how both synthetic and endogenous ligands influence TSPO conformation and oligomerization. To address this, we have combined molecular dynamics simulations with biochemical and cell-based approaches to characterize TSPO-cholesterol and TSPO-PPIX interactions. Using tryptophan-scanning mutagenesis and photoaffinity crosslinking with custom chemical tools, we identify key residues involved in TSPO-PPIX and TSPO-cholesterol binding interactions. In parallel, we investigate how PPIX, cholesterol, and synthetic TSPO ligands modulate TSPO dimerization in silico and in isolated mitochondria. Together, our studies define the effect of endogenous and synthetic TSPO ligands on oligomerization and shed light on TSPO-mediated biochemical and cellular processes in neuroinflammation. This work paves the way to rational design of next-generation TSPO-targeting compounds, enabling the development of more effective diagnostics and therapeutics to treat neuroinflammation. |
Author: Grant Berkbigler Non-Presenting Authors: Julia Lee, Dr. Adam Duerfeldt Title: Discovery and Development of a Novel PPARα Agonistic Chemotype for the Treatment of Diabetic Retinopathy Abstract: Diabetic retinopathy (DR) is the leading cause of blindness among the working population. Intravitreal injection of anti-VEGF antibodies remains the standard of care. While effective for late stage DR, this therapy requires frequent injections and fails to address ~40% of the patient population. A critical need exists for novel DR therapeutics, especially modalities that exhibit disease-modifying effects beyond pathologies driven by VEGF regulation. One target which has gained interest over recent years is the peroxisome proliferator-activated receptor alpha (PPARα). Small molecule agonism of PPARα has been shown to exhibit beneficial effects on inflammation, neovascularization, cell viability, and fibrosis, all of which are involved in DR progression and severity. In fact, fenofibrate, an orally available FDA-approved PPARα agonist, significantly decreases the progression of DR, as determined in three independent large clinical trials. Fenofibrate, however, exhibits chemotype-dependent toxicity and suffers from lack of potency and poor PPAR isoform selectivity. Towards identifying novel PPARα agonistic chemotypes, we employed a virtual high-throughput screening (vHTS) campaign, utilizing a diverse library of 352,470 compounds to identify possible PPARα binders. Virtual hits were cherry-picked and screened in vitro, resulting in the identification of GPHR-229349, a novel non-fibrate PPARα agonistic chemotype with an EC50 of 400 nM and >100-fold isoform selectivity. This poster presents our ongoing efforts towards the development of this novel small molecule PPARα agonist hit, highlighting the methodology employed and preliminary structure-activity relationships. |
Author: Maria I. Quiros Non-Presenting Authors: Poornenth Pushpanandan, Hyeokjung Kim, Edgar Arriaga, Valerie C. Pierre Title: DNA-Templated Wireframe Coordination Polymers: Novel Polyhedral Macromolecules Prevent Degradation of DNA Nanostructures in Human Serum Abstract: Abstract: DNA nanostructures are increasingly used in biomedical applications due to their ease of assembly and the programmability of the sequence-dependent base pairing. These structures enable the precise arrangement of small molecules, fluorophores, or proteins. However, the applicability of DNA nanostructures in vivo is hindered by their low stability and susceptibility to nuclease degradation.[1] Our group has previously shown that metallointercalators increase the stability of 3D DNA self-assemblies in serum and facilitate cell uptake in the presence of lipofectamine.[2] Our current work focuses on controlling the stabilization of 3D DNA nanostructures through the intercalation and further polymerization of metallointercalators. We discuss the increased stability of DNA nanostructures upon intercalation of platinum(II) complexes and polymerization of the intercalating units, and recent advances in the functionalization of the nano-assemblies. This ability to control the stability of the DNA structure has the implication for targeted drug or gene delivery. |
Author: Natalia Makaro Non-Presenting Authors: Aleksej Krunic, Jimmy Orjala Title: Discovery of Novel Metabolites from Cyanobacterium UIC 12000 Abstract: Cyanobacteria, also known as “blue-green algae,” are photosynthetic, gram-negative autotrophs that have been the focus of many recent drug discovery efforts due to their production of diverse secondary metabolites with unique chemical scaffolds. |
Author: Alexis M. Stoorza Non-Presenting Authors: Andrew J. Toensing, Erin E. Carlson, Adam S. Duerfeldt Title: Small Molecule CpxRA Modulators as Antivirulence Therapies for Urinary Tract Infections Abstract: Patients suffering from Urinary Tract Infections (UTIs) are faced with multidrug resistance and a lack of treatment options. An alternative strategy to traditional bactericidal drug design is to disarm pathogenic bacteria by targeting the regulation of virulence factors. Small-molecule CpxA phosphatase inhibitor, Cpx26, has shown efficacy in a murine UTI model; however, the mechanism of action remains unclear. We have investigated the role of Cpx26 in relevant phenotypic assays to better understand its utility. Cpx26 significantly inhibited swimming motility, biofilm formation, and adhesion to bladder epithelial cells at concentrations less than 500-fold its MIC. Combination with first-line UTI antibiotics was explored, and synergy was observed with trimethoprim/sulfamethoxazole and fosfomycin tromethamine, implying potential clinical benefit. A second generation of CpxA phosphatase inhibitors was designed with expanded and contracted C-rings to probe the spatial orientation of the primary amine in the 2,3,4,9-tetrahydro-1H-carbazol-1-amine scaffold. While Cpx26 remains our most potent compound, the analogs reaffirmed the necessity of R stereochemistry and strengthened our hypothesis of a distinct binding mode, as contracted C-rings were more tolerated over expanded rings. This work further confirms the potential for antivirulence strategies for prevalent infections, such as UTIs. |
Author: Mya Fegaras Non-Presenting Authors: Bryan Lampkin Title: Next-Generation Self-Labeling Proteins: Expanding the Toolkit with Dehalogenases Abstract: Self-labeling proteins are powerful tools for cellular imaging, bioassays, and probing protein function, combining the synthetic versatility and favorable photophysical properties of organic fluorophores with the genetic encodability of fluorescent proteins. Among these, HaloTag7, derived from a bacterial dehalogenase, remains the most widely used; however, the multiplexing capacity of current SLP systems is still limited. Here, we report the development of a dehalogenase SLP library aimed at expanding these capabilities. A panel of dehalogenases was cloned into a yeast surface display platform and screened against a range of ligand–dye pairs using spectral flow cytometry. Ligands of varying lengths were synthesized to accommodate differences in enzyme tunnel geometries and were conjugated to structurally and spectrally distinct fluorophores. Several dehalogenases exhibited measurable reactivity, with DppA showing particularly broad activity across both ligand lengths and dye scaffolds. Additionally, two sets of orthogonal dehalogenase•substrate pairs were identified, each combining spectral separation and selective reactivity. Together, these results demonstrate the potential to engineer dehalogenases with improved kinetics, enabling the development of next-generation self-labeling proteins for multiplexed applications. |
Author: Cole Friederichs Non-Presenting Authors: Quentin M. R. Gibaut, Jackson Berryman, Adam S. Duerfeldt Title: DFT and TD-DFT enabled probe design for motif driven accumulation in Gram Negative Bacteria Abstract: Drug accumulation is a major challenge in the development of antibiotics for gram-negative bacteria. With the aim of identifying structural motifs that promote accumulation, we have developed probes based on the N-Phenyl-1-naphthylamine (NPN) fluorogenic core. Compared with traditional mass spectrometry-based techniques, fluorescent probes offer unique benefits for tracking accumulation, thanks to the rapid acquisition times and readily accessible instrumentation. NPN was chosen as the parent molecule for its simple structure, ease of synthetic diversification, and solvatochromatic nature (fluorescence is environment dependent). Early attempts at derivatization with varied linkers between the naphthylamine core and motifs of interest were hindered by a lack of fluorescence retention. To elucidate the cause and identify the origin of the solvatochromic character, DFT and TD-DFT calculations were utilized. These studies, in conjunction with wet-lab fluorescence experiments, revealed that local viscosity is the driving force behind fluorescence quenching, rather than the commonly cited solvent dielectric or hydrogen-bond relaxation. Excited state dynamics revealed that molecular vibrations play a large role in fluorescence quenching through internal conversion, while intersystem crossing can play a small role in quenching. This revelation guided the focused design and synthesis of new N-aryl linked derivatives which largely retained the desired solvatochromic effects. |
Author: Thomas Pavey Non-Presenting Authors: Stephanie Heard, Barbara Adaikpoh, Gabrielle Mingolelli, Title: Target-directed discovery of new bioactive natural products Abstract: Natural products are a significant source of approved drugs in clinical. These secondary metabolites are notorious for their ability to interact with important biological targets and often function as chemical warfare agents for the producing organisms. Natural products are biosynthesized by proteins encoded by specific biosynthetic gene clusters (BGC) located within an organism’s genome. Through microbial genome sequencing, synthetic biology, and tandem mass spectrometry, new therapeutics can be discovered. Here we are working with the bacterium Burkholderia sp. FERM BP-3421, and a polyketide synthase/nonribosomal peptide synthetase gene cluster. |
Author: Abigail C. Blatz Non-Presenting Authors: Robert J. Kerns Title: Synthesis of Triphenylphosphonium (TPP+) Conjugates with Modified Linkers for Improved Mitochondrial Targeting Abstract: In the pathology of many cardiovascular, metabolic, and neurodegenerative disorders, mitochondrial dysfunction has been identified. To effectively target dysfunctional mitochondria, intracellular delivery of therapeutics and molecular probes has been explored. Currently, delocalized lipophilic cations (DLCs) and mitochondrial penetrating peptides (MPPs) have been shown to effectively target a variety of pharmacological agents to the mitochondria. Specifically, triphenyl phosphonium (TPP+) cations have been studied for mitochondrial targeting due to a large hydrophobic surface area, ionic radius, and net positive charge. In response to high mitochondrial membrane potential (∆Ψ), TPP+ conjugates rapidly accumulate in the mitochondria. Compared to the 5-to-10-fold increase in TPP+ cations in the cytosol, there is a 100-to-1000-fold increase in the concentration of TPP+ cations in the mitochondria. Longer-chain alkyl TPP+ derivatives, which are optimal for mitochondrial uptake, have been shown to increase proton leak, uncouple oxidative phosphorylation (OXPHOS), and decrease mitochondrial respiration. Therefore, lipophilic cations, such as TPP+, exhibit increased cytotoxicity. Previously, the para-substituted phenyl rings of TPP+ conjugates were varied to identify derivatives that would be less potent uncouplers of oxidative phosphorylation (OXPHOS), while maintaining mitochondrial uptake--- therefore ablating inherent cytotoxicity. Specifically, introducing a para-trifluoromethyl group on the phenyl rings of TPP (4-CF3-TPP+) significantly reduced OXPHOS uncoupling while maintaining delivery of cargo into the mitochondria. However, in the presence of aqueous DMSO, under mildly basic conditions (pH > 7), 4-CF3-TPP+ derivatives were found to undergo DMSO-mediated conversion into phosphine oxide products. Guided by this discovery, the design and synthesis of TPP+ conjugates that will “self-inactivate” under mitochondria-specific conditions is being pursued. Presented here are the synthesis and evaluation of novel TPP+ derivatives for potential β-elimination under mildly basic conditions, that exist inside the mitochondria. |
Author: Brandon B. Schuldt Non-Presenting Authors: Michael J. Grillo, Hideki Aihara, Elena Harjes, and Daniel A. Harki Title: Development of Novel 7-azaindole Fragment Ligands Targeting the DNA Mutator APOBEC3B Abstract: APOBEC3B (A3B) is a deaminase enzyme that catalyzes the conversion of cytosine to uracil in single stranded DNA. A3B is part of a larger family of APOBEC3 enzymes that act endogenously as viral restriction factors. However, over a decade of research has demonstrated that the activity and expression of A3B is harnessed in tumors to mutate the human genome by introducing large amounts of downstream C-to-T and C-to-G lesions. These factors highlight A3B as a compelling target for therapeutic inhibition; however, a selective small molecule modulator for A3B has not been developed. Our lab previously initiated a fragment-based drug discovery campaign on the catalytically active C-terminal domain (ctd) of A3B using a biophysical NMR approach. This screen led us to characterize a thiophene chemical series that binds weakly by surface plasmon resonance (SPR). The thiophene-based molecules were later advanced to various indole scaffolds to improve physiochemical properties, eventually landing on the 7-azaindole core as a promising platform for further optimization. Further structure activity relationship studies will be presented, which focused primarily on indole nitrogen substituents as well as carbon 5 and carbon 6 enumeration. These efforts identified several analogues with improved affinity to A3Bctd by SPR and appreciable aqueous solubility. In addition, we have utilized protein-observed 1H, 15N HSQC NMR as a secondary assay that identified potential interacting regions of these molecules on the enzyme. Taken together, we have developed favorable chemical matter to successfully demonstrate the ligandability of A3B. This work will further contribute to foundational efforts in the development of potent A3B inhibitors, which could extend the therapeutic window of many current cancer therapies by slowing or preventing the evolution of drug resistance mutations. |
Author: Emily L. Wells Non-Presenting Authors: Bo Hu, Julia J. Lee, and Adam S. Duerfeldt Title: Design and Synthesis of Second-Generation Heterobifunctional PPARα/STING Modulators Abstract: Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are inflammatory retinal diseases that are prominent causes of blindness in developed countries. The progression of these diseases is fueled by multiple mechanisms, including inflammation, VEGF-mediated neovascularization, and fibrosis, often limiting the efficacy of a single therapeutic solution. Two proteins known to contribute to various pathologies of DR are PPARα, a regulator of VEGF expression, and STING, a driver of inflammation. While our group has targeted both PPARα and STING independently, a shift towards a polypharmacological approach was envisioned to enable simultaneous modulation of VEGF and inflammation to elicit a more robust response. Previously, our lab reported BH400, the first dual modulator of PPARα and STING. BH400 agonizes PPARα (EC50 = 1.2 µM) and simultaneously inhibits STING (IC50 = 8.1 µM). BH400 demonstrated superior protection over single-target PPARα or STING modulation in microglial and photoreceptor cells. This poster will present second generation lead-optimization efforts for BH400. Highlights include new SAR insights and hypothesized binding orientations in both PPARα and STING for a new lead analog, EW-25-77. |
Author: Kate J. Dallmier Non-Presenting Authors: Paul. J. Hergenrother. Daniel A. Harki Title: Identification of APOBEC3A Inhibitors from a Complex-to-Diverse Natural Product Screen Abstract: |
Author: Joseph Noel-Torres Non-Presenting Authors: Madeline Hennessey, Simone Creed, Nokomis Ramos-Gonzalez, Lee-Yuan Liu-Chen, Andrew Riley Title: Second Generation SAR Studies On Akuammicine Guided By CryoEM Structure Of An Akuammicine Complex In The Kappa-Opioid Receptor Abstract: Opioids are effective pain relievers, yet long-term use can lead to addiction and respiratory depression. The primary mechanism of action of opioids is agonism towards the mu-opioid receptor to produce the analgesic effect but also result in addiction and respiratory depression. Alternatively, the kappa-opioid receptor (KOR) has been studied for its therapeutic potential in neurological conditions, including pain. Multiple agonists have been discovered with high potency, yet few have passed clinical trials due to their sedative and/or hallucinogenic properties. Thus, novel KOR ligands are essential for developing effective KOR agonists. Akuammicine (AKC), an alkaloid found in the seeds of the akuamma plant (Picralima nitida), is an agonist of the KOR that is structurally distinct from existing classes of KOR ligands. A structure-activity relationship (SAR) study revealed the importance of the C10 position of AKC to drive potency at the KOR. Animal studies of two C10-AKC derivatives, 10-Bromo-AKC and 10-Iodo-AKC, showed inhibition of compound 48/80-induced scratching with ED50 value of 3.0 and 1.3 mg/kg respectively. However, both exhibit conditioned place aversion (5 mg/kg for both) and impaired rotarod performance at effective anti-scratch doses (10 mg/kg for 10-Bromo-AKC and 5 mg/kg for 10-Iodo-AKC). A second-generation SAR study on AKC seeks to expand the C10-AKC derivative library to increase the therapeutic window of AKC ligands. Preliminary data on C10-(phenyl-substituted)-AKC derivatives show the ortho position to be most potent, followed by meta and para positions. A cryoEM structure of an AKC in complex with the KOR is being used to explain C10-AKC SAR trends. |
Author: Ngoc Pham Non-Presenting Authors: Matthew T Henke Title: Native Mass Spectrometry Implies a Potential Ligand of Gnavocin, A Narrow-spectrum Bacteriocin Produced by IBD-associated bacteria Mediterraneibacter gnavus Abstract: Alterations in gut microbial composition, known as gut dysbiosis, are one of the key factors that drive inflammation in inflammatory bowel disease (IBD). Among human gut microbes, Mediterraneibacter gnavus (formerly known as Ruminococcus gnavus) abnormally elevates in people with IBD, particularly Crohn’s disease. This elevation of M. gnavus has been observed across different cohorts, whereas it remains at low abundance in healthy individuals. Previously, our lab investigated whether M. gnavus increases in the gut could be a result of direct competition with other microbes in the gut by secreting antibacterial molecules. We discovered gnavocin, a bacteriocin with a narrow spectrum of antibacterial activity, produced by isolates of M. gnavus from people with Crohn’s disease. The gnavocin gene was found exclusively in M. gnavus and was significantly higher in IBD patients across Crohn’s disease cohorts in Spain and the United States. This suggested that M. gnavus with gnavocin could play a role in exacerbating IBD conditions. Hence, we sought to unravel the mechanism of action (MOA) of gnavocin. We used mass spectrometry and determined the protein sequence of gnavocin and that the intact mass of gnavocin was 12,083 Da. Despite its size, gnavocin retained on a 30 kDa molecular weight cutoff filter, suggesting atypical physical properties. Using native protein mass spectrometry (native MS), we observed a potential ligand bound to gnavocin, which likely indicates its mode of action and explains its narrow spectrum. Ongoing work will fully elucidate the chemical structure of this ligand. Understanding M. gnavus-derived molecules, such as gnavocin, will help clarify how specific M. gnavus strains compete and bloom in the gut, potentially leading to gut dysbiosis in Crohn’s disease. Additionally, pinpointing such factors that drive gut dysbiosis could open avenues toward treatment. |
Author: Yiming Nie Non-Presenting Authors: Nina J. Hawkins, Chunrong Li, Weiping Tang Title: Development of Rapid-Glue platform based on OPA-primary amine reaction for the rapid synthesis of molecular glue degraders Abstract: Targeted protein degradation (TPD) has become an exciting therapeutic approach to cure diseases caused by aberrantly expressed or mutated proteins, especially for undruggable targets using traditional strategies. Proteolysis-targeting chimeras (PROTACs) and molecular glue degraders (MGDs) are the most developed TPD technologies dependent on proteasomes. Compared with PROTACs, MGDs exhibit greater drug-like properties and don’t require a well-defined small molecule binding site, which opens the possibility for many undruggable targets. Screening remains a key method for discovering new MGDs. However, the screening is usually limited to the size of the library generated by traditional methods. Here, we aimed to build the Rapid-Glue platform to build the MGD library by coupling OPA-containing CRBN ligase ligands with diverse primary amines. This reaction can occur in the DMSO, and the only side product is water. The final reaction solution can be used for screening directly after the dilution. By screening in the Hibit cell lines, we identified several compounds inducing NEK7 degradation, which demonstrates our Rapid-Glue platform facilitates the discovery of MGDs. |
Author: Ameena Salim Non-Presenting Authors: Mahesh Neralkar, Rupa Bai Addanki, Lynn E. Hancock, Mark P. Farrell Title: Non-Reducing-End Functionalized High-Mannose Glycan Probes to Study Host-Glycan Recognition in Enterococcus faecalis Abstract:
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Author: Sindhuja Rangisetty Non-Presenting Authors: Rupa Bai Addanki, Ameena Salim, Pranjali Pawar, Mahesh Neralkar, Lynn E. Hancock, Mark P. Farrell Title: Differential Protecting Group Strategy for the Modular Synthesis of High Mannose N-Glycans Abstract: Enterococcus faecalis is a Gram-positive commensal bacterium of the human gut and oral cavity. Although it commonly colonizes mammalian gastrointestinal tracts by exploiting host-derived nutrients, E. faecalis can also cause opportunistic infections, including urinary tract infections (UTIs), sepsis, etc. Its intrinsic resilience and antibiotic resistance make E. faecalis an important cause of hospital-acquired infections worldwide. |
Author: Nina J. Hawkins Non-Presenting Authors: Zhen Zhang, Chunrong Li, Weiping Tang Title: Development of Novel RIPK1 Degraders to Enhance Radiotherapy Abstract: Receptor-interacting protein kinase 1 (RIPK1) is a threonine/serine kinase that serves as a critical regulator of immune responses and cell death pathways, functioning through both its catalytic kinase activity and non-catalytic scaffold function. The scaffold function of RIPK1 contributes to both intrinsic and extrinsic resistance to immune checkpoint blockades (ICBs), making it a compelling therapeutic target for enhancing cancer immunotherapy. Recent studies have highlighted RIPK1’s potential as a key modulator for improving the efficacy of immune stimulatory therapies, such as ICBs and radiotherapy. Previously, the Tang group has published a class of potent RIPK1 degraders. Our degraders demonstrated significant tumor growth suppression when combined with X-ray radiotherapy, achieving enhanced therapeutic efficacy without adverse effects on body weight. However, this class of compounds are capable of degrading RIPK2 and RIPK3, proteins that are similar in structure to RIPK1. In this poster, I will present the development of a second-generation of degraders with increased selectivity for RIPK1. This library of novel degraders has the potential to augment radiotherapy and advance cancer immunotherapy strategies with less side effects. |
Author: Jackson W. Berryman Non-Presenting Authors: Cole Friederichs, Quentin M. R. Gibaut, Adam S. Duerfeldt Title: Investigating Structure-Uptake-Relationships (SUR) in Gram-Negative Bacteria with Naphthylamine Containing Fluorescent Probes Abstract: N-Phenyl-1-Naphthylamine (NPN) is a hydrophobic, solvatochromic molecule that fluoresces in hydrophobic but not aqueous environments. This feature of NPN has made it an attractive probe to measure outer membrane (OM) integrity in gram-negative bacteria (GNB) as its ability to penetrate the OM is reliant on external stressors (e.g. heat, salts, chemicals) that compromise the OM. Given the global interest in identifying chemical motifs that enhance accumulation in GNB, NPN also presents an opportunistic scaffold to diversify for the rapid identification of structure-uptake-relationships (SUR) in GNB. This poster presents the first-generation of NPN structure-fluorescence profiling in which we investigate the effect of small motifs and linker-ology on the solvatochromic nature of the naphthylamine core. A structurally diverse library of 95 NPN derivatives was synthesized and the solvatochromic nature of each member was determined. Of those generated, 44% maintained typical solvatochromic fluorescence in the presence of Escherichia coli phospholipid extracts. Importantly, aryl-naphthylamines were found to provide the most consistent solvatochromic behavior. Emission coefficients were determined for “well-behaved” solvatochromic molecules and several were advanced to accumulation profiling in WT and membrane and/or efflux compromised E. coli, the results of which will be presented. This study motivates future work including GNB confocal microscopy and mass-spectrometry based accumulation to confirm uptake and further characterize the SURs of the library. |
Author: Tanushree R. Pal Non-Presenting Authors: Arthur C. Acuna, Bryan J. Lampkin Title: Development of Macrocyclic SF1 Peptide Probes for Spliceosome Assembly Inhibition Abstract: The spliceosome is a dynamic biomolecular complex that catalyzes the removal of introns from pre-mRNA sequences and is essential for proteome diversification. Aberrant mRNA splicing, driven by the dysregulation of cis- and trans-acting factors. is emerging as a hallmark of myelodysplastic syndromes (MDS) and other hematologic malignancies, which contain recurring mutations in spliceosomal components and exhibit splicing stress. These features make the spliceosome an attractive yet underexplored therapeutic target. This work focuses on the rational design of stapled macrocyclic peptides to inhibit early spliceosome assembly. Spliceosome assembly is initiated through 3’ splice site recognition by a ternary complex stabilized by various U2AF Homology Motif (UHM) and Ligand Motif (ULM) mediated protein-protein interactions (PPIs). We hypothesize that selective disruption of the SF1-ULM•U2AF2-UHM PPI with a macrocyclic SF1 peptide analog will stall spliceosome assembly and disrupt splicing activity. To map this PPI, we have developed two orthogonal in vitro binding assays and performed systematic alanine scanning and truncation analyses to define key interaction determinants and identify minimal binding sequences. Guided by these findings, we evaluated non-canonical tryptophan substitutions at the hotspot position and applied dithiol bis-alkylation stapling with diverse linkers to enable macrocyclization to stabilize bioactive conformations. Together, these studies establish a framework for developing a potent SF1-based macrocyclic probe and enable subsequent efforts to achieve enhanced affinity, cellular uptake, and proteolytic stability. |
Author: Ryan Friess Non-Presenting Authors: Joe McPherson, Natalia Tretyakova Title: Novel Bisubstrate Inhibitors of Ten Eleven Translocation Dioxygenase as a Strategy for Epigenetic Modulation Abstract: Ten Eleven Translocation (TET) Dioxygenases 1-3 initiate the removal of methylation marks on cytosine bases of DNA using non-heme iron, molecular oxygen, and alpha-ketoglutarate cofactor (αKG) to oxidize the methyl mark. This process is critical for epigenetic regulation of gene expression, which is key for development, cell identity, and response to infection. DNA methylation undergoes profound changes during mammalian development and is deregulated in many diseases including cancer, but disruptions has also shown to be beneficial for an enduring immune response during cancer immunotherapy. Mimics of the αKG cofactor have been developed to function as inhibitors, but lack specificity and potency. We developed a series of bisubstrate inhibitors of TET proteins containing 5-methyl-dC and αKG mimics connected by a linker in order to improve specificity and potency by targeting two nearby sites. We used an Alpha Screen assay to determine in vitro activity of these inhibitors against different TET isoforms, showing low micromolar IC50s for the most active compounds. Ester prodrugs were then shown to improve delivery into living cells. These prodrugs were then used to treat cell models to look at effects on viability and levels of DNA methylation. While no toxicity was observed, LCMS based assays showed a decrease in hydroxymethylation in active compounds. Future work is planned to expand the structure-activity relationship campaign to non-nucleoside inhibitors and to better understand how changes in structure are affecting binding. The novel TET inhibitors will be used as biological probes to better understand the roles of TET proteins in cancer and the immune response, with interest in using them to modify the epigenetic state and phenotype of T cells for cancer immunotherapy. |
Author: Alexis Mann Non-Presenting Authors: Seoyoung Kim, Matthew S. Lish, Jillian E. M. McKeon, Caroline M. Palmentiero, Julia M. Pomeroy, Colm P. Roster, James C. Morris, and Jennifer E. Golden Title: Synthesis and Structure Activity Relationship Optimization of Structurally Novel Inhibitors of Naegleria fowleri Abstract: Naegleria fowleri (aka ‘brain-eating amoebae’) is a free-living amoebae that causes primary amoebic meningoencephalitis (PAM), a rare but rapidly progressing and highly fatal infection of the central nervous system. Infection occurs when amoebae-contaminated water enters the nasal cavity, typically during recreational water exposure or use of nasal irrigation, allowing the trophozoite form to migrate to the brain. There are currently no FDA-approved treatments against N. fowleri, and existing drug cocktails are limited by poor efficacy, toxicity, and inadequate brain penetration. To address this unmet need, our group has continued efforts in this area, refining the pharmacophore of our previously disclosed tetracyclic quinazolinones which resulted from a Mannich-coupled domino quinazolinone-amidine rearrangement. The tetracyclic core, while very potent (EC50 < 25 nM), exhibited some limitations in solubility, microsomal stability, and required a chiral separation. Redesign of the scaffold resulted in analogs that exhibited improved solubility and which were synthesized in fewer synthetic steps (4 vs 7), while avoiding a chiral separation and delivering the final analogs in high enantiopurity. The evolution of the scaffold, SAR, and key data will be presented. |
Author: Moyosore O. Orimoloye Non-Presenting Authors: Pooja V. Hegde, Ziyi Jia, Neela A. Nath, Anthony D. Baughn, and Courtney C. Aldrich Title: Total Synthesis of Efflux-Resistant Mycobactins Abstract: Mycobactins, mycobacterial siderophores biosynthesized by the action of a hybrid NRPS/PKS megasynthetase, are crucial for the virulence of the prolific bacterial pathogen Mycobacterium tuberculosis. While the development of biosynthesis inhibitors is a thoroughly explored and productive paradigm in the medicinal chemistry of mycobactins, unimpeded secretion and recycling are also important for Mtb virulence and provide attractive targets. As a result of “self-poisoning” by mycobactin accumulation, for example, mutants deficient in mycobactin efflux show a 24,000-fold reduction in bacterial burden in the lungs of mice. Exploring structural requirements for efficient mycobactin efflux, we sought synthetic access to native mycobactins of various species, with particular attention to mycobactins with striking structural changes. Our synthetic route has allowed us access to Mycobactin T, the lipophilic siderophore of Mycobacterium tuberculosis (Mtb) and its hydrophilic counterpart Carboxymycobactin T. We have also prepared Mycobactin S, the mycobactin of Mycobacterium smegmatis, with reported antitubercular activity and a hypothetical p-Amino Mycobactin which may represent an alternative metabolic fate of the approved antitubercular agent p-Amino Salicylic acid. The poster will also describe ongoing efforts towards the total syntheses of mycobactins of Mycobacterium marinum, which have an unusually positioned lipid tail, and the reactivity-guided late-stage functionalization of p-Amino Mycobactin T. Campaigns towards the development of efflux-resistant siderophores, given the ubiquity of siderophores, may represent a viable, novel and generalizable antibiotic platform. |
Author: Joshua A. Legaspi Non-Presenting Authors: Jacob M. Sawyer, Samantha A. Kennelly, and Daniel A. Harki Title: Development of 3′-Deoxy-3′,4′-didehydronucleosides with Arabinose Sugars Abstract: Unsaturated nucleosides have been utilized in several highly successful antiviral drugs, such as the human immunodeficiency virus reverse transcriptase inhibitors abacavir and stavudine. Such modifications to the ribose sugar to contain an element of unsaturation and removal of the 3′-OH alcohol yields highly effective chain terminators of viral genome replication. An endogenously-derived nucleotide contains a similarly unsaturated ribose ring, 3′-deoxy-3′,4′-didehydro-cytidine-5′-triphosphate (ddhCTP), which is produced by the antiviral protein viperin through a radical S-adenosyl-methionine (SAM) mechanism. Previous work by our lab investigated the ability of thymine, inosine, uridine, guanosine, and adenosine containing nucleotides and prodrugs bearing the ddh sugar configuration to inhibit West Nile Virus (WNV) and Zika Virus (ZIKV) polymerases (as their 5′-triphosphate metabolites). Through these efforts it was identified that ddhC, ddhU, ddhA, and ddhG possessed antiviral activity. This work is focused on the development of an arabinose-containing 3′-deoxy-3′,4′-didehydro nucleosides, such as the ddh-araC. The synthesis of ddh-araC will be the focus of this presentation. |
Author: Ju Hong Non-Presenting Authors: Qiwen Liu, Nina J. Hawkins, Yaxian Liao Title: Utilizing DNA-Encoded Library for the Discovery of Structurally Diverse CRBN Ligands Abstract: Most clinically relevant PROTACs and molecular glue degraders recruit the E3 ligase Cereblon (CRBN), whose degradation activity is associated with a ligand-induced transition from an open to a closed conformation. Although CRBN plays a critical role in targeted protein degradation, the chemical space of CRBN binders remains limited and structurally biased toward glutarimide-based scaffolds. Using DNA-encoded library (DEL) screening, we identified a new class of CRBN ligands with biophysical behaviors distinct from classical thalidomide analogs. Hits from the DEL screen were validated using biochemical assays, including fluorescence polarization (FP), microscale thermophoresis (MST), and thermal shift assays (TSA). We further conducted a preliminary structure–activity relationship (SAR) study to investigate key interactions governing CRBN binding. This work identifies a class of structurally diverse CRBN ligands and demonstrates their potential as chemical tools to probe the biological differences between open and closed CRBN conformations, as well as the potential to investigate the biology of CRBN inhibition in the absence of neo-substrate degradation. |
Author: Alondra López Colón Non-Presenting Authors: Brenner J. Klein, Laura E. Hirsh, Daniel A. Harki Title: Targeting Aurora Kinase A and N-Myc with chemically stable dual degraders for high-risk neuroblastoma therapy Abstract: MYCN amplification is considered a poor prognostic marker of high-risk neuroblastoma (NB), an extracranial cancer that accounts for 15% of childhood cancer deaths. N-Myc, the product of the MYCN oncogene, is a bona fide driver of NB. To date, no clinical inhibitors of N-Myc have been developed. N-Myc is stabilized through a protein-protein interaction with Aurora Kinase A (Aurora-A); consequently, exploiting the proteasomal instability of N-Myc is a new strategy to modulate its activity. Our lab developed HLB-0532259, which utilizes PROTAC technology to induce dual degradation of Aurora-A and N-Myc. HLB-0532259 employs a selective Aurora-A-binding ligand and a thalidomide-based cereblon (CRBN) recruiting ligand, tethered through a hexyloxy linker. HLB-0532259 is potent in MYCN- and MYCN-non-amplified NB cells and shows substantial tumor regression in mouse xenografts. Unfortunately, it exhibited acute in vivo toxicity to healthy cells, as well as poor solubility and metabolic stability. We hypothesized that HLB-0532259-associated toxicities could be minimized through degraders with enhanced physicochemical properties, potency, and chemical stability. In this work, we synthesized Aurora-A/N-Myc degrader libraries with a less hydrolytically labile CRBN recruiting ligand and Aurora-A-binding ligands based on the CDK4/6 inhibitor ribociclib. In unpublished data, we find that HLB-0535282, which possesses a different CRBN ligand, is a more potent degrader against MYCN- and MYCN-non-amplified NB cells, highly selective across different CDK proteins, minimally toxic to healthy cells, and possesses less CRBN neosubstrate degradation compared to our first-generation degrader. In vitro ADME profiling showed enhanced aqueous solubility and microsomal and plasma stability. We also find that HLB-0535912, which contains a ribociclib modification, exhibits improved degradation potency and NB cytotoxicity, moderate in vitro stability, and improved N-Myc degradation kinetics. Ongoing efforts focus on merging the favorable structural features of HLB-0535282 and HLB-0535912 to yield a candidate degrader suitable for preclinical development. |
Author: Sang Vo Non-Presenting Authors: Muzafar Rather, Gorakhnath Jachak, Erick Strauss, Courtney Aldrich, Anthony Baughn, David Ferguson Title: Mechanistic Characterization of Inverted Pantothenamides (PanAMs) that Hijack M.tuberculosis Coenzyme A Biosynthesis Abstract: Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb), remains the leading cause of death from a bacterial infection, with 1.6 million deaths reported in 2023. Current treatment regimens are prolonged and increasingly ineffective against drug-resistant TB, underscoring the urgent need for novel therapeutics with new mechanisms of action. This proposal focuses on the development and mechanistic characterization of pantothenamides (PanAms), a promising class of small molecules that target the coenzyme A (CoA) biosynthesis pathway in M.tb. PanAms are bioactivated into CoA antimetabolites that disrupt essential metabolic processes, including lipid biosynthesis required for maintaining the integrity of the mycobacterial cell envelope. |
Author: Pranjali Pawar Non-Presenting Authors: Matthew Russolillo, Anil Kumar Ram, Dr. Andrew K. Godwin, Dr. Mark P. Farrell Title: Structure-Activity Relationship Studies of Novel Inhibitors Targeting the KIF15–TPX2 Interaction in Epithelial Ovarian Cancer Abstract: Structure-Activity Relationship Studies of Novel Inhibitors Targeting the KIF15–TPX2 Interaction in Epithelial Ovarian Cancer |
Author: Caroline M. Roach Non-Presenting Authors: Meareg G. Amare, Peter J. Halfmann, Jennifer E. Golden Title: Optimizing Anti-Ebola Virus Titer Reduction and Selectivity Using Non-Nucleoside Heterocycles Abstract: Ebolavirus (EBOV) is a negative, single-stranded RNA virus of the filovirus family that can cause a highly transmissible and fatal hemorrhagic fever known as Ebola virus disease (EVD) in humans. EVD typically presents as a febrile illness before progressing to severe gastrointestinal symptoms and, in critical cases, organ failure. Care is primarily focused on supportive methods, such as hydration and isolation, while treatment options, including two monoclonal antibodies and a recombinant vaccine, have limitations in access, efficacy, and mechanism of action. Evidenced by two large outbreaks and more frequent smaller ones in the past 13 years, finding new ways to inhibit EBOV is of global significance. The Golden group, in partnership with Dr. Peter Halfmann’s lab at UW-Madison, screened a collection of compounds from an internal library to identify hit compounds that exhibited anti-Ebola activity but were chemically distinct from typical nucleotide drugs, such as remdesivir. This screening revealed a hit (1) with an IC50 of 5.4 μM, no observed cytotoxicity (CC50 (Huh7ΔVP30) > 50 μM), and a viral titer reduction at 10 μM of 0.9 log. In a VSV-EBOV GP assay, this compound and similar analogs were shown not to rely on viral entry inhibition as a mechanism of action, distinguishing it from clinically relevant treatment modalities and highlighting the significance of this anti-Ebola scaffold. More than 70 analogs were synthesized based on the hit structure with the goals of improving potency and viral titer reduction to advance promising compounds to ADME and PK studies. Structure-activity trends have been evaluated in 5 structural regions to evaluate antiviral activity against EBOV in vitro. These efforts have identified a lead analog (23) with an IC50 value of 1.6 μM, a selectivity index of 20, and a reduction of EBOV titer by 5.4 log. The synthesis of these analogs, as well as the SAR and solubility and stability data, will be highlighted herein. |
Author: Clarence Peiris Non-Presenting Authors: Dr. Mersad Raeisi, Emmanuel Bonsu, Ebuka Onyeyilim, Zetandro Banarjee, Title: LIMONOIDS AS CHEMICAL TOOLS TO INVESTIGATE NEURODEGENERATIVE DISEASES Abstract: Neurodegenerative diseases (NDs) are a heterogeneous group of diseases of the nervous system, including the brain, spinal cord, and peripheral nerves that occur when nerve cells lose their function over time and ultimately die. Glutamate excitotoxicity is a cell death mechanism triggered by excessive glutamate release from neurons as well as glial cells. Evidence has emerged suggesting a probable link between glutamate excitotoxicity and neuronal cell death in major NDs such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. Limonoid natural products are a large family of oxygenated terpenoid compounds that are best known as secondary metabolites found in citrus fruits and they exhibit a wide spectrum of biological properties including neuroprotectivity. Martin group has been investigating the mechanism of action of limonoid neuroprotection against glutamate neurotoxicity. Recent progress of the research is stepping closer to unlock the molecular mechanism of limonoid neuroprotection. |
Author: Dana Sorensen Non-Presenting Authors: Nicholas Corey, Ben Stimson, Benson Storr, Jared McLendon Title: Deciphering the Cardiomyocyte–Centrosome Paradox to Identify Drug Targets for Heart Failure Abstract: This project addresses the cardiomyocyte-centrosome paradox in heart failure, where centrosome-associated genes are highly dysregulated despite the absence of canonical centrosomes in post-mitotic cardiomyocytes. Adult cardiomyocytes undergo centrosomal reduction, where centrosomal proteins relocate to perinuclear space through largely unknown mechanisms. We hypothesize that the dysregulation of centrosomal genes reflects the structural organization of the cytoskeleton, proteostasis, and contractility of cardiomyocytes. Our goal is to systematically evaluate through genetic knockouts a selected list of potential centrosomal genes identified through a bioinformatic screen. We created a pipeline to identify candidate genes, design CRISPR guides, clone and validate guides, and test them in vivo with several genes at various stages in the process. There are an estimated 716 centrosomal genes, including 31 CEP and 180 CCDC. Through bioinformatic screening, we narrowed our focus to CCDC93, CCDC141, CCDC186, CEP68, CEP97, CEP250, and PCM1. To determine candidate genes with the highest potential, we screened genes using data from the IMPC, HHF, CDVKP, GTEx, SCP, HPA, and BioGRID databases. To induce knockouts, we identified CRISPR guides on or flanking constitutive exons near the N-terminal region to induce frameshifts and Golden Gate Assembly cloning with type 3 restriction enzymes with Sanger sequencing verification. To determine cutting efficiency, we transfected guides into HT22 cells. AAV viruses with the chosen guides were injected into Cas9-J mice. Heart and liver tissues were flash frozen or preserved in OCT for further examination. Overall, we found strong indications that several centrosomal genes are likely involved in heart failure. |
Author: Atonu Chakrabortty Non-Presenting Authors: Kaleb A Feia, Melissa A Fath, David Roman, Jill M Kolesar, Jared M McLendon Title: Chemoresistance in Ovarian Cancer Emerges from Coordinated ABC Transporter Network Reprogramming Abstract: Platinum–taxane chemoresistance remains a critical obstacle in ovarian cancer management. Despite established links between ABCB1-mediated efflux and drug resistance, the role of the broader ABC transporter network remains poorly defined. We hypothesized that resistance is orchestrated through a broader ABC transporter program than driven only by ABCB1. |
Author: Nusha Mikolchak Non-Presenting Authors: Kostana Ligori, Carston Wagner Title: Free-Energy Perturbation as a Tool to Develop and Synthetically Prioritize Novel Nucleoside-Based HINT1 Binders Abstract: Computer-aided drug design (CADD) tools can provide integral insights to guide the design and synthesis of small molecule compounds. Free energy perturbation (FEP) is a computational technique wherein the differences between chemical matter are simulated through controlled alchemical intermediates, thereby allowing for accurate prediction of the free energy difference between two states. When applied to small molecule development, FEP is a robust and highly accurate method to quantitatively rank and synthetically prioritize compounds within a congeneric series. This method can be highly advantageous to utilize for nucleosides, as nucleoside-based small molecules can often be both difficult and time-consuming to synthesize. In the case of histidine nucleotide triad binding protein (HINT1), a ubiquitously expressed phosphoramidase, nearly all known small molecule substrates and inhibitors are nucleoside-based. HINT1 is essential for the activation of nucleotide phosphoramidate prodrugs and its inhibition has shown nociceptive effects in vivo. Further elucidation of HINT1 function and inhibition is complicated due to a synthetic bottleneck in the design and synthesis of novel HINT1 binders. To mitigate this, we aim to develop a relative FEP model to preemptively guide the synthesis of new binders. We have synthesized and experimentally tested several nucleoside small molecules to develop our relative FEP model and have established its predictive capabilities. To test our model, we have synthesized several untested small molecules with the objective of prospectively determining their predicted binding affinities by FEP, prior to experimental testing. |
Author: Milo J. Garceau Non-Presenting Authors: Val J. Watts, David L. Roman Title: Optimization of NanoBRET Platform for a Screen of Selective Adenylyl Cyclase 8 Inhibitors to Treat Alcohol Use Disorders Abstract: Adenylyl cyclase 8 (AC8) is a membrane bound protein that catalyzes the formation of cAMP from ATP. AC8 has been implicated in various neurological disorders, including alcohol use disorders (AUDs). Additionally, in an alcohol preferring mouse model, AC8-/- knockout decreases alcohol seeking behaviors. Attempts to inhibit AC8, however, have proven challenging. As a member of the adenylyl cyclase family, achieving selective inhibition of AC8 is at the root of this challenge. To achieve selective inhibition of AC8 over other AC isoforms, we have focused on disrupting calmodulin (CaM) mediated activation of AC8. This mechanism of activation is shared only by one other isoform: AC1. The binding sites of CaM on AC8 and AC1 are not conserved, and their differences provide hope that selective inhibition is possible. Identifying a selective and efficacious inhibitor of the AC8-CaM interaction could provide a novel first-in-class molecule that shows selectivity for AC8 inhibition to treat AUDs. To accomplish this we are developing a high throughput screen using NanoBRET to identify inhibitors of the AC8-CaM PPI. |
Author: Joe McPherson Non-Presenting Authors: Molly Sneddon, Richard Begynah, Kesavan Babu, Marcus Fischer, Natalia Tretyakova, William Pomerantz Title: Histone Code Expansion of the Epigenetic Reader BPTF Enables the Design of New Bivalent Inhibitors Abstract: The N-terminal peptide tails of histones contain post translational modifications (PTMs) that are interpreted by epigenetic reader proteins. One such reader is the Bromodomain PHD finger Transcription Factor (BPTF). BPTF is an emerging oncogenic target in multiple cancer types including colorectal, breast, lung, and bladder cancers. Understanding the landscape of protein-protein interactions (PPIs) – including histone-BPTF engagement – is necessary for elucidating the role of BPTF in disease and guiding the development of chemical probes. BPTF contains two chromatin binding domains: a plant homeodomain (PHD) finger and a bromodomain (BRD). The BPTF PHD binds to trimethyllysine (Kme3) at position four on histone H3 (H3K4me3). The BPTF BRD is thought to primarily engage acetyllysine (Kac) PTMs on histone H4; however, emerging evidence has suggested that the BPTF BRD can also interact with multiple Kac modifications on histone H3. Despite these findings, it is unclear if a single Kac residue on histone H3 predominates BPTF BRD interactions and if this binding event is simultaneous with PHD finger recognition of H3K4me3. |
Author: Elliott Peterson Non-Presenting Authors: William Pomerantz Title: Predicting Cereblon-based Neosubstrate Degradation and Ligand Discovery by Protein-Observed 19F NMR Abstract: Cereblon is an E3 ubiquitin ligase used by PROTACs and molecular glues to mediate proteasomal degradation of target proteins. When bound by imide-containing ligands, Cereblon undergoes conformational remodeling that enables the ubiquitination and degradation of multiple non-physiological proteins known as neosubstrates. The thalidomide-based class of Cereblon ligands, known as IMiDs, have been shown to degrade >150 zinc finger-containing proteins through ligand-mediated Cereblon-neosubstrate interactions and cause significant toxicities in patients, limiting the full clinical utility of current Cereblon-based therapies. Here, we describe the design and validation of a fluorotryptophan-labeled Cereblon construct to enable protein-observed fluorine-NMR (PrOF NMR) experiments. These sensitive fluorine reporter labels will be used to analyze ligand-enabled Cereblon structural remodeling in solution, as well as to screen for new ligands. Currently, this work has demonstrated that ligand binding in the tryptophan-lined Cereblon binding domain can be observed through NMR chemical shift perturbation, with distinct NMR spectral fingerprints observed for the 5- and 7-fluorotryptophan-labeled Cereblon constructs. This ongoing work supports the use of fluorotryptophan-labeled Cereblon and PrOF NMR as a tool for future studies assessing the scope of Cereblon remodeling upon ligand binding and identifying novel chemotypes beyond IMiDs for modulating Cereblon function. |
Author: Kostana Ligori Non-Presenting Authors: Nusha Mikolchak, Carston R. Wagner Title: Privileges and Drawbacks of Guanosine Scaffolds in Photocatalytic Proximity Labelling Probes Abstract: Intracellular photocatalytic proximity labelling presents an avenue for dissection of protein interactions in a spatiotemporal manner without disrupting biological processes. To ensure such results, careful probe design is crucial to ensure biologically relevant conformations and interactions are not affected upon binding and subsequent labelling. Our lab has adopted intracellular photocatalytic proximity labelling to study Histidine Triad Binding Nucleotide 1 (HINT1) and its role in Mu Opioid Receptor (MOR) – N-Methyl-D-Aspartic Acid Receptor (NMDAR) crosstalk. We have previously demonstrated that HINT1 inhibitors provide selective modulation of the crosstalk in vivo, eliciting a range of pharmacological responses that are not recapitulated in binding affinity trends. Photocatalytic proximity labelling would allow for the study of HINT1 interactions upon inhibition to deduce changes in protein partners that determine pharmacological outcomes. Our current probe design features riboflavin tetraacetate (RFTA) as a photocatalyst, attached to our inhibitors via an alkyl triazole linker. As a nucleoside binding protein, HINT1 inhibitors contain modified and endogenous nucleoside structures that may pose synthetic challenges. The work presented in this poster focuses on taking advantage of controlled labelling due to photocatalyst quenching abilities of guanosine and navigating the peculiarities of guanosine chemistry, notably intermolecular interactions such as G-G base pair stacking and other intramolecular interactions. |
Author: Farzana Kabir Non-Presenting Authors: Farzana Kabir (1), Katherine F. M. Jones (1), Mackenzie K. Wyllie (1), Dyana N. Kenanova (2), Michelle R. Arkin (2), and Daniel A. Harki (*1) Title: Disulfide Tethering Screening for APOBEC3A Inhibitor Development Abstract: APOBEC3A (A3A) is a single stranded (ss) DNA cytidine deaminase that contributes to mutagenesis, oncogenesis, and cancer therapy resistance. Despite its therapeutic relevance, selective and potent small molecule inhibitors of A3A remain elusive. A3A presents significant challenges for conventional drug discovery due to its compact active site and lack of deep, well-defined binding pockets. To address these limitations, we have pursued a non-traditional discovery strategy by employing mass spectrometry-based disulfide tethering to target a surface-exposed cysteine proximal to the active site. A library of 1840 disulfide containing fragments was screened against A3A cysteine mutants. Fragments that engage the protein through favorable noncovalent interactions undergo disulfide exchange with the solvent accessible thiol, enabling site directed covalent capture while minimizing non-specific reactivity. Follow-up dose response, ssDNA displacement, and deaminase activity assays identified twelve hits. Subsequent triage with active A3A revealed four fragments that covalently modify C64 near the active site, supporting their potential as covalent inhibitor scaffolds. Screening hits have now advanced to medicinal chemistry optimization to deliver lead scaffolds for potent and selective A3A inhibitors, as well as chemical probes to interrogate A3A biology, ultimately supporting therapeutic strategies aimed at suppressing A3A mutagenesis-driven therapy resistance in cancer. |