Regulation of ES cell differentiation by functional and conformational modulation of p53
Regulation of ES cell differentiation by functional and conformational modulation of p53
复制标题
DOI：
10.1093/emboj/16.20.6217
复制
发表时间：
1997-10-15
期刊：
影响因子：
11.4
通讯作者：
Wagner, EF
中科院分区：
文献类型：
--
作者：
Sabapathy, K;Klemm, M;Wagner, EF
胚胎干（ES）细胞系被用来检查p53在体外分化过程中的作用。未分化的ES细胞仅以野生型构象表达高水平的p53，可被单克隆抗体PAb 246免疫沉淀，并且发现p53具有功能活性，如通过其特异性结合DNA和激活靶基因转录的能力所确定的。体外分化导致p53水平降低，并且其构象状态转变为突变形式，未分化的ES细胞中功能性p53的存在使它们对UV辐射超敏感，而分化的细胞对UV处理有抗性，缺乏p53的ES细胞在未分化和分化状态下都表现出增强的增殖，并且发现伴随分化的凋亡减少。此外，经历凋亡的野生型ES细胞表达功能性p53。温度敏感的p53 val135突变体在野生型ES细胞中的表达导致在39 ℃时采用突变体构象时伴随分化的凋亡减少。这些数据表明，p53的功能失活允许分化细胞逃避凋亡，并表明构象开关可以调节失活过程。
Embryonic stem (ES) cell lines were used to examine the role of p53 during in vitro differentiation. Undifferentiated ES cells express high levels of p53 exclusively in the wild-type conformation, immunoprecipitable by monoclonal antibody PAb246, and p53 was found to be functionally active as determined by its ability to bind DNA specifically and to activate transcription of target genes, Differentiation in vitro resulted in a decrease in the levels of p53 and in a shift in its conformational status to the mutant form, detectable by monoclonal antibody PAb240, with a concomitant loss of functional activity, The presence of functional p53 in the undifferentiated ES cells renders them hypersensitive to UV irradiation, whereas the differentiated cells were resistant to UV treatment, ES cells lacking p53 exhibit enhanced proliferation in both the undifferentiated and differentiated state, and apoptosis accompanying differentiation was found to be reduced, Furthermore, wild-type ES cells undergoing apoptosis expressed functional p53. Expression of the temperature-sensitive p53val135 mutant in wild-type ES cells resulted in a reduction of apoptosis accompanying differentiation when it adopted a mutant conformation at 39 degrees C, These data demonstrate that functional inactivation of p53 allows differentiating cells to escape from apoptosis, and suggest that the conformational switch could regulate the inactivation process.