Discovery of a molecular glue promoting CDK12-DDB1 interaction to trigger cyclin K degradation
- Elife. 2020 Aug 17;9:e59994. doi: 10.7554/eLife.59994.
- 1. College of Life Sciences, Beijing Normal University, Beijing, China.
- 2. National Institute of Biological Sciences, Beijing, China.
- 3. School of Life Sciences, Peking University, Beijing, China.
- 4. Graduate School of Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.
- 5. Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China.
- # Contributed equally.
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.