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Sanchez TW, Ronzetti MH, Owens AE, Antony M, Voss T, Wallgren E, Talley D, Balakrishnan K, Leyes Porello SE, Rai G, Marugan JJ, Michael SG, Baljinnyam B, Southall N, Simeonov A, Henderson MJ. Real-Time Cellular Thermal Shift Assay to Monitor Target Engagement. ACS Chem Biol 2022; 17:2471-2482. [PMID: 36049119 PMCID: PMC9486815 DOI: 10.1021/acschembio.2c00334] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Determining a molecule's mechanism of action is paramount during chemical probe development and drug discovery. The cellular thermal shift assay (CETSA) is a valuable tool to confirm target engagement in cells for a small molecule that demonstrates a pharmacological effect. CETSA directly detects biophysical interactions between ligands and protein targets, which can alter a protein's unfolding and aggregation properties in response to thermal challenge. In traditional CETSA experiments, each temperature requires an individual sample, which restricts throughput and requires substantial optimization. To capture the full aggregation profile of a protein from a single sample, we developed a prototype real-time CETSA (RT-CETSA) platform by coupling a real-time PCR instrument with a CCD camera to detect luminescence. A thermally stable Nanoluciferase variant (ThermLuc) was bioengineered to withstand unfolding at temperatures greater than 90 °C and was compatible with monitoring target engagement events when fused to diverse targets. Utilizing well-characterized inhibitors of lactate dehydrogenase alpha, RT-CETSA showed significant correlation with enzymatic, biophysical, and other cell-based assays. A data analysis pipeline was developed to enhance the sensitivity of RT-CETSA to detect on-target binding. RT-CETSA technology advances capabilities of the CETSA method and facilitates the identification of ligand-target engagement in cells, a critical step in assessing the mechanism of action of a small molecule.
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Owens AE, Iannotti MJ, Sanchez TW, Voss T, Kapoor A, Hall MD, Marugan JJ, Michael S, Southall N, Henderson MJ. High-Throughput Cellular Thermal Shift Assay Using Acoustic Transfer of Protein Lysates. ACS Chem Biol 2022; 17:322-330. [PMID: 35119255 PMCID: PMC10026039 DOI: 10.1021/acschembio.1c00760] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cellular thermal shift assay (CETSA) is a valuable method to confirm target engagement within a complex cellular environment, by detecting changes in a protein's thermal stability upon ligand binding. The classical CETSA method measures changes in the thermal stability of endogenous proteins using immunoblotting, which is low-throughput and laborious. Reverse-phase protein arrays (RPPAs) have been demonstrated as a detection modality for CETSA; however, the reported procedure requires manual processing steps that limit throughput and preclude screening applications. We developed a high-throughput CETSA using an acoustic RPPA (HT-CETSA-aRPPA) protocol that is compatible with 96- and 384-well microplates from start-to-finish, using low speed centrifugation to remove thermally destabilized proteins. The utility of HT-CETSA-aRPPA for guiding structure-activity relationship studies was demonstrated for inhibitors of lactate dehydrogenase A. Additionally, a collection of kinase inhibitors was screened to identify compounds that engage MEK1, a clinically relevant kinase target.
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Affiliation(s)
- Ashley E. Owens
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, USA
| | - Michael J. Iannotti
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, USA
| | - Tino W. Sanchez
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, USA
| | - Ty Voss
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, USA
| | - Abhijeet Kapoor
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, USA
| | - Matthew D. Hall
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, USA
| | - Juan J. Marugan
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, USA
| | - Sam Michael
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, USA
| | - Noel Southall
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, USA
| | - Mark J. Henderson
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, 20850, USA
- Corresponding Author: Mark Henderson;
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