Identification of phosphorylation sites on transcription factor Sp1 in response to DNA damage and its accumulation at damaged sites
Identification of phosphorylation sites on transcription factor Sp1 in response to DNA damage and its accumulation at damaged sites
复制标题
DOI：
10.1016/j.cellsig.2008.06.007
复制
发表时间：
2008-10-01
影响因子：
4.8
通讯作者：
Tsurumi, Tatsuya
中科院分区：
文献类型：
--
作者：
Iwahori, Satoko;Yasui, Yoshihiro;Tsurumi, Tatsuya
DNA损伤诱导Sp1转录因子的过度磷酸化。我们已经证明，电离辐射相关的DNA双链断裂（DSBs）以atm依赖的方式诱导Sp1上至少Ser-56和Ser-101残基的磷酸化。紫外线照射或羟基脲（HU）诱导的复制胁迫只导致Ser-101残基磷酸化。此外，用HU处理ATM-缺陷细胞中的ATM-和rad3相关蛋白（ATR）的沉默消除了Ser-101的磷酸化。因此，Sp1上Ser-101的磷酸化似乎是对依赖于ATM和ATR的DNA损伤的一般反应。虽然通过siRNA靶向使Sp1表达沉默导致对电离辐射（IR）的敏感性增加，Ser-101磷酸化并不影响Sp1响应启动子的转录活性。激光共聚焦显微镜分析显示Ser-101磷酸化Sp1和Ser-1981磷酸化ATM共定位，受影响的位点代表dsb。这些观察结果表明磷酸化Sp1可能在损伤位点的DNA修复中发挥作用，而不是在转录调节中起作用。(C) 2008爱思唯尔公司版权所有。
DNA damage induces hyper-phosphorylation of the Sp1 transcriptional factor. We have demonstrated that ionizing radiation-associated DNA double-strand breaks (DSBs) induce phosphorylation of at least Ser-56 and Ser-101 residues on Sp1 in an ATM-dependent manner. UV irradiation- or hydroxyurea (HU)-induced replicative stress results in phosphorylation of only the Ser-101 residue. Furthermore, silencing of the ATM- and Rad3-related protein (ATR) in ATM-deficient cells treated with HU abrogated the Ser-101 phosphorylation. Thus, phosphorylation of Ser-101 on Sp1 appears to be a general response to DNA damage dependent on both ATM and ATR. Although silencing of Sp1 expression by siRNA targeting resulted in an increase in sensitivity to ionizing radiation (IR), the Ser-101 phosphorylation did not affect transcriptional activity from the Sp1 responsive promoter. Confocal laser microscopy analysis revealed co-localization of phosphorylated Sp1 at Ser-101 with phosphorylated ATM at Ser-1981, the affected sites representing DSBs. These observations suggest that phosphorylated Sp1 might play a role in DNA repair at damage sites rather than functioning in transcriptional regulation. (C) 2008 Elsevier Inc. All rights reserved.