College of Life Sciences, Beijing Normal University, Beijing, China.
National Institute of Biological Sciences, Beijing, China.
Elife. 2020 Aug 17;9:e59994. doi: 10.7554/eLife.59994.
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.
分子胶降解剂介导靶蛋白与泛素-蛋白酶体系统成分之间的相互作用，导致选择性蛋白降解。在这里，我们报道了一种通过高通量筛选发现的新型分子胶 HQ461。通过在人类癌细胞中进行功能丧失和功能获得的遗传筛选，然后进行生化重建，我们表明 HQ461 通过促进 CDK12 和 DDB1-CUL4-RBX1 E3 泛素连接酶之间的相互作用起作用，导致 CDK12 相互作用蛋白 Cyclin K (CCNK) 的多泛素化和降解。由 HQ461 介导的 CCNK 降解削弱了 CDK12 的功能，导致 CDK12 底物的磷酸化减少、DNA 损伤反应基因下调和细胞死亡。HQ461 的结构-活性关系分析揭示了 5-甲基噻唑-2-胺药效团的重要性，并导致 HQ461 衍生物的活性得到改善。我们的研究揭示了一种新的分子胶，它将靶蛋白直接募集到 DDB1 上，从而绕过了对底物特异性受体的需求，为靶向蛋白降解提供了一种新策略。
