Inactivation of the SR protein splicing factor ASF/SF2 results in genomic instability
Inactivation of the SR protein splicing factor ASF/SF2 results in genomic instability
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DOI：
10.1016/j.cell.2005.06.008
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发表时间：
2005-08-12
期刊：
影响因子：
64.5
通讯作者：
Manley, JL
中科院分区：
文献类型：
--
作者：
Li, XL;Manley, JL
SR蛋白是一个前mRNA剪接因子家族，目前认为在后生动物细胞的mRNA代谢中起着多种作用。在这里，我们提供的证据表明，一个原型SR蛋白，ASF/SF 2，出乎意料地需要维持基因组的稳定性。我们首先表明，ASF/SF 2的体内耗竭导致可能由于DNA重排的超突变表型，反映在DNA双链断裂和高分子量DNA片段的快速出现。从ASF/SF 2耗尽细胞的DNA分析表明，转录基因的非模板链是单链的，由于形成了RNA：DNA杂交体，R环结构。RNase H的稳定过表达抑制了DNA片段化和超突变表型。ASF/SF 2的直接作用的指示，防止R环的形成在体外转录反应重建。我们的研究结果支持一种模型，通过该模型，ASF/SF 2通过RNA聚合酶11向新生转录物的募集防止了致突变R环结构的形成。
SR proteins constitute a family of pre-mRNA splicing factors now thought to play several roles in mRNA metabolism in metazoan cells. Here we provide evidence that a prototypical SR protein, ASF/SF2, is unexpectedly required for maintenance of genomic stability. We first show that in vivo depletion of ASF/SF2 results in a hypermutation phenotype likely due to DNA rearrangements, reflected in the rapid appearance of DNA double-strand breaks and high-molecular-weight DNA fragments. Analysis of DNA from ASF/ SF2-depleted cells revealed that the nontemplate strand of a transcribed gene was single stranded due to formation of an RNA:DNA hybrid, R loop structure. Stable overexpression of RNase H suppressed the DNA-fragmentation and hypermutation phenotypes. Indicative of a direct role, ASF/SF2 prevented R loop formation in a reconstituted in vitro transcription reaction. Our results support a model by which recruitment of ASF/SF2 to nascent transcripts by RNA polymerase 11 prevents formation of mutagenic R loop structures.