Identification of the RNA polymerase II subunit hsRPB7 as a novel target of the von Hippel-Lindau protein
Identification of the RNA polymerase II subunit hsRPB7 as a novel target of the von Hippel-Lindau protein
复制标题
DOI：
10.1093/emboj/cdg410
复制
发表时间：
2003-08-15
期刊：
影响因子：
11.4
通讯作者：
Wu, G
中科院分区：
文献类型：
--
作者：
Na, X;Duan, HO;Wu, G
von Hippel-Lindau（VHL）肿瘤抑制基因的失活与遗传性VHL疾病和散发性透明细胞肾细胞癌（CCRCC）有关。VHL相关肿瘤高度血管化，这是与血管内皮生长因子（VEGF）过度产生相关的特征。VHL蛋白（pVHL）是泛素连接酶E3复合物的组分，靶向底物蛋白进行泛素化和随后的蛋白酶体降解。在这里，我们报告说，pVHL可以直接结合到人类RNA聚合酶II第七亚基（hsRPB 7）通过其β-结构域，和自然发生的β-结构域突变可以减少pVHL hsRPB 7的结合。将野生型pVHL引入携带内源性突变型无功能pVHL的人肾癌细胞系中，促进hsRPB 7的泛素化和蛋白酶体降解，并减少其核积累。pVHL还可抑制hsRPB 7诱导的VEGF启动子的转录激活、mRNA表达和VEGF蛋白分泌。总之，我们的研究结果表明，hsRPB 7是VHL泛素化复合物的下游靶点，pVHL可能通过靶向hsRPB 7通过泛素化途径降解并阻止VEGF表达来调节血管生成。
Inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene is linked to the hereditary VHL disease and sporadic clear cell renal cell carcinomas (CCRCC). VHL-associated tumors are highly vascularized, a characteristic associated with overproduction of vascular endothelial growth factor (VEGF). The VHL protein (pVHL) is a component of the ubiquitin ligase E3 complex, targeting substrate proteins for ubiquitylation and subsequent proteasomic degradation. Here, we report that the pVHL can directly bind to the human RNA polymerase II seventh subunit (hsRPB7) through its beta-domain, and naturally occurring beta-domain mutations can decrease the binding of pVHL to hsRPB7. Introducing wild-type pVHL into human kidney tumor cell lines carrying endogenous mutant non-functional pVHL facilitates ubiquityl ation and proteasomal degradation of hsRPB7, and decreases its nuclear accumulation. pVHL can also suppress hsRPB7-induced VEGF promoter transactivation, mRNA expression and VEGF protein secretion. Together, our results suggest that hsRPB7 is a downstream target of the VHL ubiquitylating complex and pVHL may regulate angiogenesis by targeting hsRPB7 for degradation via the ubiquitylation pathway and preventing VEGF expression.