Negative Regulation of Chk2 Expression by p53 Is Dependent on the CCAAT-binding Transcription Factor NF-Y*
Negative Regulation of Chk2 Expression by p53 Is Dependent on the CCAAT-binding Transcription Factor NF-Y*
复制标题
DOI：
10.1074/jbc.m403232200
复制
发表时间：
2004-06
影响因子：
4.8
通讯作者：
T. Matsui;Yuko Katsuno;Tomoharu Inoue;F. Fujita;T. Joh;Hiroyuki Niida;H. Murakami;M. Itoh;M. Na
中科院分区：
文献类型：
--
作者：
T. Matsui;Yuko Katsuno;Tomoharu Inoue;F. Fujita;T. Joh;Hiroyuki Niida;H. Murakami;M. Itoh;M. Na
激酶Chk 2和肿瘤抑制因子p53参与哺乳动物细胞中不明确的调节相互作用。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。电离辐射也触发了人结肠直肠癌细胞HCT 116（p53+/+）中Chk 2的磷酸化和随后的下调;其同基因突变体HCT 116（p53-/-）细胞（缺乏功能性p53）的辐射诱导Chk 2磷酸化，但不诱导其下调。此外，HCT 116（p53+/+）细胞组成性表达显性负性p53（V143 A）不能抑制照射后Chk 2的表达。在HCT 116（p53+/+）细胞中的报告基因分析显示，野生型p53抑制，而显性负性p53突变体增加，人Chk 2基因启动子的活性。突变分析表明，位于启动子-152和-138核苷酸之间的CCAAT盒负责p53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-YA的显性失活突变体消除了p53对Chk 2启动子活性的影响。这些结果表明，p53负调控Chk 2基因转录通过调节NF-γ功能，这种调节可能是重要的DNA损伤修复后，细胞重新进入细胞周期。
The kinase Chk2 and tumor suppressor p53 participate in an ill 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 colorectal HCT116 (p53+/+) cancer cells; irradiation of its isogenic mutant HCT116 (p53–/–) cells, which lack functional p53, induced Chk2 phosphorylation but not its down-regulation. In addition, HCT116 (p53+/+) cells constitutively expressing a dominant negative p53 (V143A) failed to suppress Chk2 expression after irradiation. Reporter gene assays in HCT116 (p53+/+) cells revealed that wild-type p53 repressed, whereas a dominant negative p53 mutant increased, the activity of the human Chk2 gene promoter. Mutational analysis showed that a CCAAT box located between nucleotides –152 and –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-YA abolished the effect of p53 on Chk2 promoter activity. These results suggest that p53 negatively regulates Chk2 gene transcription through modulation of NF-Y function and that this regulation may be important for reentry of cells into the cell cycle after DNA damage is repaired.