Small Ubiquitin-like Modifier (SUMO) Isoforms and Conjugation-independent Function in DNA Double-strand Break Repair Pathways
Small Ubiquitin-like Modifier (SUMO) Isoforms and Conjugation-independent Function in DNA Double-strand Break Repair Pathways
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DOI：
10.1074/jbc.c114.582122
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发表时间：
2014-08-01
影响因子：
4.8
通讯作者：
Parvin, Jeffrey D.
中科院分区：
文献类型：
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作者：
Hu, Yiheng;Parvin, Jeffrey D.
小泛素样修饰物（SUMO）蛋白在DNA双链断裂（DSB）修复中起作用，但三种主要亚型的途径特异性尚未确定。在我们通过RNA干扰消除内源性SUMO蛋白的实验中，我们发现SUMO 1在同源重组（HR）或非同源末端连接（NHEJ）的所有子途径中发挥作用，而SUMO 2/3是主要NHEJ途径所需的，称为保守NHEJ，但在其他DSB修复途径中可有可无。令我们惊讶的是，我们发现UBC 9（独特的SUMO E2酶）的耗尽对HR或替代NHEJ（Alt-NHEJ）没有影响，但对保守NHEJ是必需的。与该结果一致，非缀合突变体和野生型SUMO 1蛋白在HR和Alt-NHEJ中的功能相似。这些结果详细说明了特定SUMO同种型在哺乳动物细胞中DSB修复中的功能作用，并揭示了SUMO 1在HR或Alt-NHEJ中作为游离蛋白而不是作为蛋白缀合物发挥功能。
Small ubiquitin-like modifier (SUMO) proteins act in DNA double-strand break (DSB) repair, but the pathway specificity of the three major isoforms has not been defined. In experiments in which we depleted the endogenous SUMO protein by RNAi, we found that SUMO1 functioned in all subpathways of either homologous recombination (HR) or non-homologous end joining (NHEJ), whereas SUMO2/3 was required for the major NHEJ pathway, called conservative NHEJ, but dispensable in other DSB repair pathways. To our surprise, we found that depletion of UBC9, the unique SUMO E2 enzyme, had no effect in HR or alternative NHEJ (Alt-NHEJ) but was required for conservative NHEJ. Consistent with this result, both non-conjugatable mutant and wild-type SUMO1 proteins functioned similarly in HR and Alt-NHEJ. These results detail the functional roles of specific SUMO isoforms in DSB repair in mammalian cells and reveal that SUMO1 functions in HR or Alt-NHEJ as a free protein and not as a protein conjugate.