Negative regulation of Chk2 expression by p53

p53 对 Chk2 表达的负调控

• 批准号: 13670543
• 负责人: JOH Takashi
• 金额: $ 2.18万
• 依托单位: Nagoya City University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13670543/
• 关键词: p53; Chk2 (hCds1); cell cycle; a poptosis; DNA damage; Chk2(hCds1); chk2; 細胞周期; NF-Y; 胃癌

The kinase Chk2 and tumor suppressor p53 participate in an in-defined regulatory interaction in mammalian cells. The abundance of Chk2 mRNA and protein has now been shown to be decreased by the induction of p53 in Saos2 cells. Ionizing radiation also triggered the phosphorylation and subsequent down-regulation of Chk2 in human fibroblasts ; irradiation of HeLa cells, which lack functional p53, induced Chk2 phosphorylation but not its down-regulation. Reporter gene assays in A172 cells revealed that wild-type p53 repressed, whereas a dominant negative p53 mutant increased, the activity of the human Chkk2 gene promoter. Mutational analysis showed that a CCAAT box located between nucleotides -152〜-138 of the promoter was responsible for its negative regulation by p53. Electrophoretic mobility-shift assays demonstrated that the transcription factor NF-Y binds to this CCAAT sequence. A dominant negative mutant of NF-Y abolished the effect of p53 on Chk2 promoter activity. Finally, expression of Chk2 under the control of a p53-insensitive promoter in A172 cells delayed reentry into the cell cycle after G2-M arrest induced by ionizing irradiation. These results suggest that p53 negatively regulates Chk2 gene transcription through modulation of NF-Y function, and that this regulation is important for reentry of cells into the cell cycle after DNA damage.

激酶Chk 2和肿瘤抑制因子p53在哺乳动物细胞中参与一种不确定的调节相互作用。Chk 2 mRNA和蛋白质的丰度现在已被证明通过在Saos 2细胞中诱导p53而降低。电离辐射也引发了人成纤维细胞中Chk 2的磷酸化和随后的下调;缺乏功能性p53的HeLa细胞的辐射诱导Chk 2磷酸化，但不诱导其下调。A172细胞中的报告基因测定显示，野生型p53抑制，而显性负性p53突变体增加，人Chkk 2基因启动子的活性。突变分析表明，位于启动子-152-138之间的CCAAT盒负责p53对该启动子的负调控。电泳迁移率变动分析表明，转录因子NF-Y结合到这个CCAAT序列。NF-Y的显性失活突变体消除了p53对Chk 2启动子活性的影响。最后，在A172细胞中，在p53不敏感启动子的控制下表达Chk 2延迟电离辐射诱导的G2-M期阻滞后重新进入细胞周期。这些结果表明，p53通过调节NF-γ功能负调控Chk 2基因转录，并且这种调节对于DNA损伤后细胞重新进入细胞周期是重要的。