Prajapati Paresh, Gohel Dhruv, Shinde Anjali, Roy Milton, Singh Kritarth, Singh Rajesh
Department of Biochemistry, Faculty of Science, The M.S. University of Baroda, Vadodara 390 002, Gujarat, India; Spinal Cord and Brain Injury Research Center, Department of Pathology and Laboratory Medicine, University of Kentucky, 800 S. Limestone, Lexington, KY 40536, USA; Neuroscience, University of Kentucky, Lexington, KY 40536, USA.
Department of Biochemistry, Faculty of Science, The M.S. University of Baroda, Vadodara 390 002, Gujarat, India.
Cell Signal. 2020 Dec;76:109777. doi: 10.1016/j.cellsig.2020.109777. Epub 2020 Sep 10.
Emerging evidence suggests that ubiquitin mediated post translational modification is a critical regulatory process involved in diverse cellular pathways including cell death. During ubiquitination, E3 ligases recognize target proteins and determine the topology of ubiquitin chains. Recruitment of E3 ligases to targets proteins under stress conditions including oxidative stress and their implication in cell death have not been systemically explored. In the present study, we characterized the role of TRIM32 as an E3 ligase in regulation of oxidative stress induced cell death. TRIM32 is ubiquitously expressed in cell lines of different origin and form cytoplasmic speckle like structures that transiently interact with mitochondria under oxidative stress conditions. The ectopic expression of TRIM32 sensitizes cell death induced by oxidative stress whereas TRIM32 knockdown shows a protective effect. The turnover of TRIM32 is enhanced during oxidative stress and its expression induces ROS generation, loss of mitochondrial transmembrane potential and decrease in complex-I activity. The pro-apoptotic effect was rescued by pan-caspase inhibitor or antioxidant treatment. E3 ligase activity of TRIM32 is essential for oxidative stress induced apoptotic cell death. Furthermore, TRIM32 decreases X-linked inhibitor of apoptosis (XIAP) level and overexpression of XIAP rescued cells from TRIM32 mediated oxidative stress and cell death. Overall, the results of this study provide the first evidence supporting the role of TRIM32 in regulating oxidative stress induced cell death, which has implications in numerous pathological conditions including cancer and neurodegeneration.
新出现的证据表明，泛素介导的翻译后修饰是一个关键的调控过程，涉及包括细胞死亡在内的多种细胞途径。在泛素化过程中，E3连接酶识别靶蛋白并决定泛素链的拓扑结构。在包括氧化应激在内的应激条件下，E3连接酶向靶蛋白的募集及其在细胞死亡中的作用尚未得到系统研究。在本研究中，我们表征了TRIM32作为一种E3连接酶在调节氧化应激诱导的细胞死亡中的作用。TRIM32在不同来源的细胞系中普遍表达，并形成细胞质斑点样结构，在氧化应激条件下与线粒体短暂相互作用。TRIM32的异位表达使氧化应激诱导的细胞死亡敏感化，而TRIM32的敲低则显示出保护作用。在氧化应激期间，TRIM32的周转增强，其表达诱导活性氧生成、线粒体跨膜电位丧失和复合物I活性降低。泛半胱天冬酶抑制剂或抗氧化剂处理可挽救促凋亡作用。TRIM32的E3连接酶活性对于氧化应激诱导的凋亡细胞死亡至关重要。此外，TRIM32降低X连锁凋亡抑制蛋白（XIAP）水平，XIAP的过表达使细胞免受TRIM32介导的氧化应激和细胞死亡。总体而言，本研究结果提供了首个证据，支持TRIM32在调节氧化应激诱导的细胞死亡中的作用，这在包括癌症和神经退行性变在内的多种病理状况中具有重要意义。
