Estève Pierre-Olivier, Chin Hang Gyeong, Pradhan Sriharsa
New England Biolabs, 32 Tozer Road, Beverly, MA 01915, USA.
Proc Natl Acad Sci U S A. 2005 Jan 25;102(4):1000-5. doi: 10.1073/pnas.0407729102. Epub 2005 Jan 18.
DNA (cytosine-5)-methyltransferase (DNMT) 1 participates in transcriptional repression of genes by methylation-dependent and -independent mechanisms. Here, DNMT1 is shown to bind p53 and colocalize in the nucleus. DNMT1-mediated methylation is stimulated by p53 in vitro. Upon p53 induction, a reporter construct containing the antiapoptotic gene survivin promoter, which contains a natural p53 binding site, was methylated in WT HCT116 cells but not in DNMT1 null or p53 null cells. Endogenous survivin gene repression involves cooperation between DNMT1 and p53 and is relieved by introduction of DNMT1- or p53-specific small inhibitory RNA. DNMT1 null cells did not exhibit a significant repressive effect for p53 responsive survivin and cdc25C gene expression compared with the parental cells. Normal human fibroblasts also exhibited similar DNMT1- and p53-mediated methylation of the survivin promoter, suggesting cooperation between p53 and DNMT1 in gene silencing.
DNA（胞嘧啶-5）-甲基转移酶（DNMT）1通过依赖甲基化和不依赖甲基化的机制参与基因的转录抑制。在此，研究表明DNMT1与p53结合并共定位于细胞核。在体外，p53可刺激DNMT1介导的甲基化。p53诱导后，含有抗凋亡基因survivin启动子（该启动子含有一个天然p53结合位点）的报告基因构建体在野生型HCT116细胞中发生甲基化，但在DNMT1基因敲除细胞或p53基因敲除细胞中未发生甲基化。内源性survivin基因的抑制涉及DNMT1和p53之间的协同作用，并且通过导入DNMT1或p53特异性小干扰RNA可解除这种抑制。与亲代细胞相比，DNMT1基因敲除细胞对p53反应性的survivin和cdc25C基因表达未表现出明显的抑制作用。正常人成纤维细胞也表现出类似的DNMT1和p53介导的survivin启动子甲基化，提示p53和DNMT1在基因沉默中存在协同作用。
