Ding Guangjin, Chen Peilin, Zhang Hui, Huang Xiaojie, Zang Yi, Li Jiwen, Li Jia, Wong Jiemin
From the Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241.
the National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, and.
J Biol Chem. 2016 Sep 16;291(38):20125-35. doi: 10.1074/jbc.M116.727214. Epub 2016 Aug 3.
As a protein critical for DNA maintenance methylation and cell proliferation, UHRF1 is frequently highly expressed in various human cancers and is considered as a drug target for cancer therapy. In a high throughput screening for small molecules that induce UHRF1 protein degradation, we have identified the HSP90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG). We present evidence that UHRF1 interacts with HSP90 chaperone complex and is a novel HSP90 client protein. Pharmacological inhibition of HSP90 with 17-AAG or 17-dimethylaminoethylamino-17-demethoxygeldanamycin results in UHRF1 ubiquitination and proteasome-dependent degradation. Interestingly, this HSP90 inhibitor-induced UHRF1 degradation is independent of CHIP and CUL5, two previously identified ubiquitin E3 ligases for HSP90 client proteins. In addition, this degradation is dependent neither on the intrinsic E3 ligase of UHRF1 nor on the E3 ligase SCF(β-TRCP) that has been implicated in regulation of UHRF1 stability. We also provide evidence that HSP90 inhibitors may suppress cancer cell proliferation in part through its induced UHRF1 degradation. Taken together, our results identify UHRF1 as a novel HSP90 client protein and shed light on the regulation of UHRF1 stability and function.
作为一种对DNA维持甲基化和细胞增殖至关重要的蛋白质，UHRF1在多种人类癌症中经常高度表达，并被视为癌症治疗的药物靶点。在一项针对诱导UHRF1蛋白降解的小分子的高通量筛选中，我们鉴定出了HSP90抑制剂17-烯丙基氨基-17-去甲氧基格尔德霉素（17-AAG）。我们提供的证据表明，UHRF1与HSP90伴侣复合物相互作用，并且是一种新型的HSP90客户蛋白。用17-AAG或17-二甲基氨基乙氨基-17-去甲氧基格尔德霉素对HSP90进行药理学抑制会导致UHRF1泛素化和蛋白酶体依赖性降解。有趣的是，这种HSP90抑制剂诱导的UHRF1降解不依赖于CHIP和CUL5，这两种先前确定的HSP90客户蛋白的泛素E3连接酶。此外，这种降解既不依赖于UHRF1的内在E3连接酶，也不依赖于与UHRF1稳定性调节有关的E3连接酶SCF(β-TRCP)。我们还提供证据表明，HSP90抑制剂可能部分通过其诱导的UHRF1降解来抑制癌细胞增殖。综上所述，我们的结果确定UHRF1为一种新型的HSP90客户蛋白，并揭示了UHRF1稳定性和功能的调节机制。
