Molecular-glue degraders mediate interactions between target proteins and components of the ubiquitin-proteasome system to cause selective protein degradation. Here, we report a new molecular glue HQ461 discovered by high-throughput screening. Using loss-of-function and gain-of-function genetic screening in human cancer cells followed by biochemical reconstitution, we show that HQ461 acts by promoting an interaction between CDK12 and DDB1-CUL4-RBX1 E3 ubiquitin ligase, leading to polyubiquitination and degradation of CDK12-interacting protein Cyclin K (CCNK). Degradation of CCNK mediated by HQ461 compromised CDK12 function, leading to reduced phosphorylation of a CDK12 substrate, downregulation of DNA damage response genes, and cell death. Structure-activity relationship analysis of HQ461 revealed the importance of a 5-methylthiazol-2-amine pharmacophore and resulted in an HQ461 derivate with improved potency. Our studies reveal a new molecular glue that recruits its target protein directly to DDB1 to bypass the requirement of a substrate-specific receptor, presenting a new strategy for targeted protein degradation.
All data generated or analysed during this study are included in the manuscript and supporting files. Sequencing data have been deposited in GEO (GSE153700 and GSE153707).
Discovery of a molecular glue promoting CDK12-DDB1 interaction to trigger Cyclin K degradation [CRISPR]NCBI Gene Expression Omnibus, GSE153700.
Discovery of a molecular glue promoting CDK12-DDB1 interaction to trigger Cyclin K degradation [WES]NCBI Gene Expression Omnibus, GSE153707.
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Wade Harper, Harvard Medical School, United States
© 2020, Lv et al.
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