Chemical Proteomic Strategies to Probe Novel Kinase and Serine Hydrolase Function in Native Biological Systems

Chemical proteomic profiling is a powerful chemical tool that enables the analysis of protein activity in native biological systems. This strategy can be tailored to access diverse enzyme classes to aid in the: (1) identification of novel protein targets; (2) discovery of novel pharmacological compounds; and (3) characterization of enzyme active sites. The work contained in this dissertation exploits current chemical probe technologies to reveal new insights in enzyme function and novel applications for existing small molecule inhibitors.
In Chapters 2 and 3, we utilize ATP acyl phosphate probes to characterize lipid enzyme diacylglycerol kinase (DGK) and reported type 1 DGKα inhibitor ritanserin. We define, for the first time, the unique regions responsible for ATP and ligand binding in all five DGK subtypes and discover multiple protein kinase off-targets of ritanserin. We also use fragment-based inhibitor discovery to profile the unique activities of distinct structural regions of ritanserin.
In Chapters 4 and 5, we utilize chemical proteomic profiling to discover novel clinical applications for existing small molecule inhibitors. We discover a new ritanserin-dependent kinase network that broadly kills lung tumor cell types, and identify c-RAF as a target of ritanserin that may be a key target mediating its anticancer activity. Additionally, we identify a serine hydrolase inhibitor capable of enhancing CD4+ T cell function that could potentially be utilized to enhance current cancer immunotherapy strategies.