Maria J Ortiz-Ruiz, Olajumoke Popoola, Konstantinos Mitsopoulos, Robert Te-Poele, Rahul S Samant, Gary Box, Will Court, Alexis De Haven Brandon, Sharon Gowan, Aurelie Mallinger, Toby Roe, Kate Swabey, Melanie Valenti, Bissan Al-Lazikani, Julian Blagg, Christina Esdar, Kai Schiemann, Dirk Wienke, Suzanne A Eccles, Paul Workman, Paul A Clarke
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引用次数: 0
Abstract
The Mediator complex is a regulator of gene expression, influencing chromatin structure and RNA polymerase II-mediated transcription. Its activity is controlled by a protein kinase module, which includes cyclin-dependent kinases 8 and 19, that phosphorylates RNA polymerase II and transcription factors to regulate gene expression. Using orthogonal approaches combining chemical and genetic tools, we demonstrated the selectivity of our small-molecule inhibitors derived from 3,4,5-trisubstituted pyridine and 3-methyl-1H-pyrazolo[3,4-b]pyridine chemical series in human colorectal cell culture and tumor xenograft models. The lack of activity of our inhibitors in CDK8/19 double knockout models, with respect to molecular, proliferative, and antitumor end points, revealed their specificity and dependence on these kinases. Using our chemical probes and knockout models, we explored Mediator kinase function in human colorectal cancer cells. Phospho-proteome profiling revealed substrates enriched with transcription and chromatin regulators, while promoter reporter experiments identified transcription factor binding sites, including TCF/LEF and AP1, regulated by Mediator kinases. Additionally, altered phosphorylation of several Mediator subunits suggests a mechanism for the rapid regulation of the Mediator complex. Overall, our results demonstrate that CDK8 and CDK19 play pivotal roles in regulating gene expression associated with oncogene activation and signaling pathways. Further studies are warranted to elucidate their broader cellular roles and regulatory mechanisms. The selective inhibitors validated in this study will provide valuable tools for such mechanistic investigations into Mediator kinase functions and their potential therapeutic exploitation.
期刊介绍:
ACS Chemical Biology provides an international forum for the rapid communication of research that broadly embraces the interface between chemistry and biology.
The journal also serves as a forum to facilitate the communication between biologists and chemists that will translate into new research opportunities and discoveries. Results will be published in which molecular reasoning has been used to probe questions through in vitro investigations, cell biological methods, or organismic studies.
We welcome mechanistic studies on proteins, nucleic acids, sugars, lipids, and nonbiological polymers. The journal serves a large scientific community, exploring cellular function from both chemical and biological perspectives. It is understood that submitted work is based upon original results and has not been published previously.