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Deubiquitylase OTUD6B Governs pVHL Stability in an Enzyme-Independent Manner and Suppresses Hepatocellular Carcinoma Metastasis.
Advanced Science ( IF 14.3 ) Pub Date : 2020-03-08 , DOI: 10.1002/advs.201902040
Xinxin Liu 1 , Xiaoli Zhang 1 , Zhiqiang Peng 1 , Chunnan Li 1 , Ze Wang 1 , Chanjuan Wang 1 , Zhikang Deng 1 , Bo Wu 1 , Yu Cui 1 , Zhanxin Wang 2 , Chun-Ping Cui 1 , Min Zheng 3, 4 , Lingqiang Zhang 1
Affiliation  

Hypoxia inducible factors (HIFs) are the key transcription factors that allow cancer cells to survive hypoxia. HIF's stability is mainly controlled by von Hippel-Lindau (pVHL)-mediated ubiquitylation. Unlike sporadic clear-cell renal carcinomas, VHL mutation is rarely observed in hepatocellular carcinoma (HCC) and the regulatory mechanisms of pVHL-HIF signaling remain elusive. Here, it is shown that deubiquitylase ovarian tumor domain-containing 6B (OTUD6B) suppresses HCC metastasis through inhibiting the HIF activity. OTUD6B directly interacts with pVHL, decreases its ubiquitylation and proteasomal degradation to reduce HIF-1α accumulation in HCC cells under hypoxia. Surprisingly, OTUD6B limits the ubiquitylation of pVHL independent of its deubiquitylase activity. OTUD6B couples pVHL and elongin B/C to form more CBCVHL ligase complex, which protects pVHL from proteasomal degradation. Depletion of OTUD6B results in the dissociation of CBCVHL complex and the degradation of pVHL by Trp Asp repeat and suppressors of cytokine signaling box-containing protein 1 (WSB1). In human HCC tissues, the protein level of OTUD6B is positively correlated with pVHL, but negatively with HIF-1α and vascular endothelial growth factor. Low expression of OTUD6B predicts poor patient survival. Furthermore, OTUD6B gene is a direct transcriptional target of HIF-1α and upregulated upon hypoxia. These results indicate a previously unrecognized feedback loop consisting of OTUD6B, pVHL, and HIF-1α, and provide insights into the targeted hypoxic microenvironment for HCC therapy.

中文翻译:


去泛素化酶 OTUD6B 以不依赖于酶的方式控制 pVHL 稳定性并抑制肝细胞癌转移。



缺氧诱导因子(HIF)是癌细胞在缺氧条件下存活的关键转录因子。 HIF 的稳定性主要由 von Hippel-Lindau (pVHL) 介导的泛素化控制。与散发性透明细胞肾癌不同,在肝细胞癌 (HCC) 中很少观察到 VHL 突变,并且 pVHL-HIF 信号传导的调节机制仍然难以捉摸。在此,研究表明,含有去泛素化酶卵巢肿瘤结构域 6B (OTUD6B) 通过抑制 HIF 活性来抑制 HCC 转移。 OTUD6B 直接与 pVHL 相互作用,降低其泛素化和蛋白酶体降解,从而减少缺氧下 HCC 细胞中 HIF-1α 的积累。令人惊讶的是,OTUD6B 限制 pVHL 的泛素化,与其去泛素化酶活性无关。 OTUD6B 将 pVHL 和 elongin B/C 偶联,形成更多的 CBCVHL 连接酶复合物,从而保护 pVHL 免遭蛋白酶体降解。 OTUD6B 的耗竭会导致 CBCVHL 复合物解离,并通过 Trp Asp 重复序列和含有细胞因子信号传导盒的蛋白 1 (WSB1) 抑制子降解 pVHL。在人肝癌组织中,OTUD6B的蛋白水平与pVHL呈正相关,但与HIF-1α和血管内皮生长因子呈负相关。 OTUD6B 低表达预示患者生存率较差。此外,OTUD6B 基因是 HIF-1α 的直接转录靶标,并在缺氧时上调。这些结果表明了一个以前未被识别的由 OTUD6B、pVHL 和 HIF-1α 组成的反馈环,并为 HCC 治疗的靶向低氧微环境提供了见解。
更新日期:2020-04-21
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