Cell nonhomologous end joining capacity controls SAF-A phosphorylation by DNA-PK in response to DNA double-strand breaks inducers
Cell nonhomologous end joining capacity controls SAF-A phosphorylation by DNA-PK in response to DNA double-strand breaks inducers
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DOI：
10.4161/cc.8.22.10025
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发表时间：
2009-11-15
期刊：
影响因子：
4.3
通讯作者：
Calsou, Patrick
中科院分区：
文献类型：
--
作者：
Britton, Sebastien;Froment, Carine;Calsou, Patrick
为了确定新的磷酸化位点响应DNA双链断裂（DSB）诱导剂，我们已经分离出KU 70上的磷酸化位点。出乎意料的是，针对该位点产生的兔抗血清与DNA DSB诱导剂处理的细胞中的120 kDa蛋白质发生交叉反应。我们将这种蛋白鉴定为SAF-A/hnRNP U，它是一种含有结合DNA或RNA的区域的丰富且必需的核蛋白。磷酸化位点定位在S59位置，在序列背景中有利于DNA-PK磷酸化位点的“S-疏水”一致模型。该位点仅被DNA-PK磷酸化以响应DNA DSB诱导剂。此外，这种磷酸化的程度和持续时间与细胞通过非同源末端连接修复DSB的能力呈负相关。这些结果为hnRNP家族与DNA损伤反应之间带来了新的联系。此外，SAF-A上的磷酸化位点可作为DNA-PK活性的生物标志物，用于DNA-PK激活剂或抑制剂的学术研究和临床分析。
Aiming to identify novel phosphorylation sites in response to DNA double-strand breaks (DSB) inducers, we have isolated a phosphorylation site on KU70. Unexpectedly, a rabbit antiserum raised against this site cross-reacted with a 120 kDa protein in cells treated by DNA DSB inducers. We identified this protein as SAF-A/hnRNP U, an abundant and essential nuclear protein containing regions binding DNA or RNA. The phosphorylation site was mapped at S59 position in a sequence context favoring a "S-hydrophobic" consensus model for DNA-PK phosphorylation site in vivo. This site was exclusively phosphorylated by DNA-PK in response to DNA DSB inducers. In addition, the extent and duration of this phosphorylation was in inverse correlation with the capacity of the cells to repair DSB by Nonhomologous End Joining. These results bring a new link between the hnRNP family and the DNA damage response. Addtionaly, the mapped phospho-site on SAF-A might serve as a potential bio-marker for DNA-PK activity in academic studies and clinical analyses of DNA-PK activators or inhibitors.