Target-based Assays and Screening Strategies for Chemical Probe and Therapeutic Lead Discovery

National Center For Advancing Translational Sciences

Investigators

Linked publications & trials

Abstract

This project includes the development of biochemical and target-focused assays based on specific protein or nucleic acid targets implicated in disease. The assay designs are considered in the context of analysis and progression strategies for evaluation of a wide range of compound classes using high throughput screening technologies. There is a strong emphasis on methods development research to advance assay and lead discovery efficiency. Complementing these activities, we also explore and devise approaches for the interrogation of complex chemical libraries (e.g., natural product extracts, mRNA display). The work from this program is used to support a range of grant applications, program objectives and prototype projects. The following are on-going: Targeting protein palmitoylation with small molecules. In collaboration with A. Banerjee (NICHD, NIH) we have developed 1536-well compatible protein palmitoyl acyl transferase assays to evaluate chemical libraries for potential inhibitors of the enzyme as possible therapeutic leads for the large number of diseases to which this class of enzyme have been linked. These compounds are also anticipated to have value as structural, functional, and pharmacological probes. Assay development to enable discovery of novel small molecule antagonists of the receptor guanylate cyclase Npr1. In collaboration with M. Hoon (NIDCR, NIH) we have developed assays of the b-type natriuretic peptide (BNP) receptor, Npr1. Recently the agonist, BNP was shown to be required for the transmission of itch sensation between peripheral and spinal cord nerves. The Npr1 assays were employed in large-scale chemical library screening to identify novel natriuretic peptide receptor antagonists to investigate the potential of pharmacological treatments of chronic itch, a condition that results in long-term unremitting urge to scratch that significantly degrades the quality of life for sufferers (Solinski HJ et al., in press). Most recently, in collaboration with the NCATS ASPIRE program and Mytide Therapeutics we are assessing synthetic peptide analogs of the receptors natural cyclic peptide agonist as novel modulators of Npr1 signaling. SIRPa-CD47 Protein-protein interaction. In collaboration with T. Miller (Paradigm Shift Therapeutics) and D. Roberts (NCI, NIH) our goal is to leverage the broad potential of CD47 as a molecular target in several tumor types to create therapeutics that protect normal tissue from chemo and radiation therapy while differentially enhancing the effects of these therapies on the tumor. We designed and validated several biochemical SIRPa-CD47 protein-protein interaction assays (Burgess TL et al., 2020). Using these assays, we are investigating the potential SIRPa-CD47 complex disruption activity of several compounds identified from large-scale high throughput chemical library screening. Chorismate mutase inhibitors. In collaboration with J. Padia (PrimeTime Life Sciences) this project seeks to develop a quantitative high throughput screening (qHTS) assay for the identification of small molecule inhibitors of chorismate mutase (CM). CM is an important enzyme found in plants and microorganisms required for the biosynthesis of the aromatic amino acids, phenylalanine and tyrosine. Mammals cannot carry out the de novo biosynthesis of aromatic amino acids and must rely on dietary sources. Thus, a potent and selective drug-like inhibitor of CM would be a valuable antimicrobial agent, particularly for antimicrobial resistant infections. Due to assay conditions not amenable to standard qHTS processes, this project will serve as a model for the application of mass spectrophotometry-based screening with the RapidFire technology in collaboration with the Dingyin Tao in Analytical Chemistry. Targeting G proteins with small molecules. Fibrous dysplasia of bone (McCune-Albright syndrome) is a hyperfunctioning endocrinopathy resulting from mis-sense mutations in the small -subunit of the G-protein, Gs leading to increased levels of cellular cAMP. The aim of this project is to develop biochemical and cell-based assays suitable for evaluating the activity and coupling of G proteins to their GPCRs and effector adenylyl cyclase (Getz RA et al., 2019). For example, by enabling a quantitative high throughput screening assay using the R201C mutant form of Gs to identify small molecules capable of antagonizing the R201C Gs adenylyl cyclase-activating conformation. SARS CoV-2 Nsp1 Inhibitors. The nonstructural viral protein, nsp1 is a virulence factor of SARS-CoV2 that inhibits gene expression in infected cells. The resultant inhibition of host gene expression restricts antiviral signaling and the interferon response. In the closely related virus SARS-CoV1, mutations in Nsp1 create highly attenuated viruses, which have been used in vaccine trials. Here in collaboration with the Structural Virology Laboratory of Prof. Jeffrey Kieft at the University of Colorado School of Medicine, Prof. Anna-Lena Steckelberg, Ph.D. at Columbia University, and Prof. Hiro Suga, Ph.D. of The University of Tokyo we are developing a compound screening and validation assay series to identify inhibitors of SARS-CoV2 Nsp1 function. Metallo beta-lactamases. With 2.8 million acquired antibiotic-resistant infections yearly in the US, leading to >35,000 deaths, antibiotic resistance remains a significant and increasing public health challenge. -lactamases which hydrolyze and thereby inactivate a broad range of clinically used -lactam drugs are a major global cause of antibiotic resistance. New Delhi metallo--lactamases (NDM) can hydrolyze the last-resort carbapenems. In collaboration with Prof. Michael W. Crowder, Ph.D. and colleagues we are developing machine leaning-enabled screening paradigms to discovery novel metallo--lactamases inhibitors chemotypes. Inhibition of Hedgehog autoprocessing and cholesteroylation. The Hedgehog (Hh) signaling pathway is essential to embryonic cell differentiation as Hh protein concentration gradients are critical to proper embryonic morphologic development, where pathway malfunction can result in cancer. In a collaboration with Dr. Callahan, an expert in the biochemistry of Hh cholesteroylation, which occurs via the self-catalyzed endo-proteolysis of the hedgehog precursor protein by activated cholesterol bound to the precursor C-terminus, we are developing, optimizing, and validating cell-based qHTS assays for the identification of Hh autoprocessing inhibitors. Inhibitors of this process may have potential as anticancer agents.