Komarova E A, Chernov M V, Franks R, Wang K, Armin G, Zelnick C R, Chin D M, Bacus S S, Stark G R, Gudkov A V
Department of Genetics, University of Illinois at Chicago, 60607, USA.
EMBO J. 1997 Mar 17;16(6):1391-400. doi: 10.1093/emboj/16.6.1391.
To analyze the involvement of p53-dependent transcriptional activation in normal development and in response to DNA damage in vivo, we created transgenic mice with a lacZ reporter gene under the control of a p53-responsive promoter. Five independent strains showed similar patterns of transgene expression. In untreated animals, lacZ expression was limited to the developing nervous system of embryos and newborn mice and was strongly decreased in the adult brain. gamma-irradiation or adriamycin treatment induced lacZ expression in the majority of cells of early embryos and in the spleen, thymus and small intestine in adult mice. Transgene expression was p53 dependent and coincided with the sites of strong p53 accumulation. The lacZ-expressing tissues and early embryos, unlike other adult tissues and late embryos, are characterized by high levels of p53 mRNA expression and respond to DNA damage by massive apoptotic cell death. Analysis of p53-null mice showed that this apoptosis is p53 dependent. These data suggest that p53 activity, monitored by the reporter lacZ transgene, is the determinant of radiation and drug sensitivity in vivo and indicate the importance of tissue and stage specificity of p53 regulation at the level of mRNA expression.
为了分析p53依赖的转录激活在正常发育及体内对DNA损伤应答中的作用，我们构建了在p53应答启动子控制下带有lacZ报告基因的转基因小鼠。五个独立品系显示出相似的转基因表达模式。在未处理的动物中，lacZ表达局限于胚胎和新生小鼠的发育中的神经系统，在成体大脑中则显著降低。γ射线照射或阿霉素处理可诱导早期胚胎的大多数细胞以及成年小鼠的脾脏、胸腺和小肠中lacZ表达。转基因表达依赖于p53，并与p53强烈积累的位点一致。与其他成年组织和晚期胚胎不同，表达lacZ的组织和早期胚胎的特征在于高水平的p53 mRNA表达，并通过大量凋亡性细胞死亡对DNA损伤作出反应。对p53基因敲除小鼠的分析表明这种凋亡依赖于p53。这些数据表明，由报告基因lacZ转基因监测的p53活性是体内辐射和药物敏感性的决定因素，并表明在mRNA表达水平上p53调节的组织和阶段特异性的重要性。
