Biology subjects

Houles, T.

Publications and source records attributed to Houles, T..

3 recordsLinked to original sources

bioRxiv2025

CDK11 activates CDK12 to trigger the elongation of RNA Polymerase II

CDK11 is an essential cyclin-dependent kinase in higher eukaryotes, yet its specific substrates and functional roles have remained elusive. Our findings reveal that CDK11 is functionally analogous to the yeast Bur1 kinase, phosphorylating the repeat region of hSpt5 and the linker domain of Rpb1 in RNA Polymerase II (Pol II). Inhibition of CDK11 results in a significant reduction of active Pol II not only at transcription start sites but also along gene bodies. Further investigation finds that CDK11 is crucial for the phosphorylation and activation of CDK12, which is essential for the elongation of Pol II. Moreover, we find that CDK10 can partially compensate for the function of CDK11. Combining with earlier functional elucidation of CDK9 from us, the consequent roles of CDK7/8, CDK9, CDK10/11, and CDK12/13 in transcription regulation in metazoans are established.

biochemistry↗

bioRxiv2023

The CDK12 inhibitor SR-4835 functions as a molecular glue that promotes cyclin K degradation in melanoma

CDK12 is a transcriptional cyclin-dependent kinase (CDK) that interacts with cyclin K to regulate different aspects of gene expression. The CDK12-cyclin K complex phosphorylates several substrates, including RNA polymerase II (Pol II), and thereby regulates transcription elongation, RNA splicing, as well as cleavage and polyadenylation. Because of its implication in cancer, including breast cancer and melanoma, multiple pharmacological inhibitors of CDK12 have been identified to date, including THZ531 and SR-4835. While both CDK12 inhibitors affect Poll II phosphorylation, we found that SR-4835 uniquely promotes cyclin K degradation via the proteasome. Using loss-of-function genetic screening, we found that SR-4835 cytotoxicity depends on a functional CUL4-RBX1-DDB1 ubiquitin ligase complex. Consistent with this, we show that DDB1 is required for cyclin K degradation, and that SR-4835 promotes DDB1 interaction with the CDK12-cyclin K complex. Docking studies and structure-activity relationship analyses of SR-4835 revealed the importance of the benzimidazole side-chain in molecular glue activity. Together, our results indicate that SR-4835 acts as a molecular glue that recruits the CDK12-cyclin K complex to the CUL4-RBX1-DDB1 ubiquitin ligase complex to target cyclin K for degradation.

molecular biology↗

bioRxiv2020

RIOK2 phosphorylation by RSK promotes synthesis of the human small ribosomal subunit

Ribosome biogenesis lies at the nexus of various signaling pathways coordinating protein synthesis with cell growth and proliferation. This process is regulated by well-described transcriptional mechanisms, but a growing body of evidence indicates that other levels of regulation exist. Here we show that the Ras/mitogen-activated protein kinase (MAPK) pathway stimulates post-transcriptional stages of human ribosome synthesis. We identify RIOK2, a pre-40S particle assembly factor, as a new target of the MAPK-activated kinase RSK. RIOK2 phosphorylation by RSK promotes cytoplasmic maturation of late pre-40S particles, which is required for optimal protein synthesis and cell proliferation. RIOK2 phosphorylation facilitates its release from pre-40S particles and its nuclear re-import, prior to completion of small ribosomal subunits. Our results bring a detailed mechanistic link between the Ras/MAPK pathway and the maturation of human pre-40S particles, which open a hitherto poorly explored area of ribosome biogenesis.

molecular biology↗