背景:前列腺癌(PC)是最常见的肿瘤,是全球男性癌症相关死亡的第二大原因。Hippo肿瘤抑制途径在哺乳动物中高度保守,在肿瘤发生中起重要作用。YAP是Hippo途径的主要关键效应子之一。然而,支持PC中异常YAP表达的机制仍有待表征。
方法:Westernblot检测ATXN3和YAP的蛋白表达,同时通过实时PCR检测YAP靶基因。CCK8试验用于检测细胞活力;transwell侵袭试验用于测量PC的侵袭能力。异种移植物肿瘤模型用于体内研究。蛋白质稳定性测定用于检测YAP蛋白质降解。免疫沉淀法用于检测YAP和ATXN3之间的相互作用域。基于泛素的免疫沉淀实验用于检测YAP上发生的特定泛素化方式。
结果:在本研究中,我们鉴定了ATXN3,泛素特异性蛋白酶家族中的一种DUB酶,作为PC中YAP的真正去泛素酶。ATXN3被证明与,去泛素,并以去泛素化活性依赖性方式稳定YAP。ATXN3的缺失降低了PC中YAP蛋白水平和YAP/TEAD靶基因的表达,包括CTGF,ANKRD1和CYR61。进一步的机理研究表明,ATXN3的Josephin域与YAP的WW域相互作用。ATXN3通过抑制K48特异性聚泛素化过程稳定YAP蛋白。此外,ATXN3耗竭显著降低PC细胞增殖,入侵和茎样特性。由ATXN3耗竭诱导的效应可以通过进一步的YAP过表达来挽救。
结论:一般来说,我们的发现确立了ATXN3作为YAP的去泛素化酶的催化作用,并为PC的治疗提供了可能的靶点.视频摘要。
Prostate cancer (PC) is the most common neoplasm and is the second leading cause of cancer-related deaths in men worldwide. The Hippo tumor suppressor pathway is highly conserved in mammals and plays an important role in carcinogenesis. YAP is one of major key effectors of the Hippo pathway. However, the mechanism supporting abnormal YAP expression in PC remains to be characterized.
Western blot was used to measure the protein expression of ATXN3 and YAP, while the YAP target genes were measured by real-time PCR. CCK8 assay was used to detect cell viability; transwell invasion assay was used to measure the invasion ability of PC. The xeno-graft tumor model was used for in vivo study. Protein stability assay was used to detect YAP protein degradation. Immuno-precipitation assay was used to detect the interaction domain between YAP and ATXN3. The ubiquitin-based Immuno-precipitation assays were used to detect the specific ubiquitination manner happened on YAP.
In the present study, we identified ATXN3, a DUB enzyme in the ubiquitin-specific proteases family, as a bona fide deubiquitylase of YAP in PC. ATXN3 was shown to interact with, deubiquitylate, and stabilize YAP in a deubiquitylation activity-dependent manner. Depletion of ATXN3 decreased the YAP protein level and the expression of YAP/TEAD target genes in PC, including CTGF, ANKRD1 and CYR61. Further mechanistic study revealed that the Josephin domain of ATXN3 interacted with the WW domain of YAP. ATXN3 stabilized YAP protein via inhibiting K48-specific poly-ubiquitination process on YAP protein. In addition, ATXN3 depletion significantly decreased PC cell proliferation, invasion and stem-like properties. The effects induced by ATXN3 depletion could be rescued by further YAP overexpression.
In general, our findings establish a previously undocumented catalytic role for ATXN3 as a deubiquitinating enzyme of YAP and provides a possible target for the therapy of PC. Video Abstract.