野生型p53及相关调控基因的转录、翻译水平与肠道干细胞分化的关系

Relationship between changs of transcription,translation of wild-type p53 and its relative genes and the differenation of stem cells in gut

目的 探讨野生型 p53(wtp53)基因及其相关调控基因转录、翻译水平的变化与肠道干细胞分化的关系。方法 利用逆转录 多聚酶链反应 (RT PCR)和免疫组织化学技术 ,以细胞分化标志肝脂肪酸结合蛋白 (L Fabp)mRNA水平为动态参照 ,分别检测大鼠胚胎期E1 4d ,E1 7d,E1 9d和幼鼠期P1d,P2d,P7d,P2 8d及成年大鼠小肠细胞内p53mRNA、p2 1mRNA及其蛋白表达。 结果 从胚胎E1 9d至成年大鼠 ,RT PCR能够检测到小肠细胞内L Fabp的mRNA ,其中P2d,L Fabp的mRNA含量最高 ,证实这个期间为肠道干细胞高分化阶段。从胚胎到成年大鼠 ,小肠细胞p2 1mRNA及其蛋白表达均为阴性 ,p53mRNA水平无明显变化。然而从E1 4d～P2d ,小肠上皮细胞p53蛋白信号呈逐渐增强趋势。P7d以后至成年期 ,p53蛋白信号为阴性。结论 在肠道干细胞迅速分化期 ,p53蛋白高表达可能是因为其半衰期延长 ,最终导致蛋白量累积的结果 ,而与转录水平无关 ,提示蛋白的稳定性对于p53调节肠道干细胞分化期基因的稳定性十分重要 ,另外 ,p53蛋白调节肠道干细胞的分化机制与p2

Objective To investigate the relationship between the changes of transcription,translation of the gene wild type p53 and its relative genes and the differentiation of stem cells in gut.Methods RT PCR and immunohistochemical techniques were used to detect the expressions of p53,p21 and L Fabp in small intestine epithelial cells at different development stages. Among those parameter, L Fabp mRNA was used as the marker of cell differentiation.Results There was the expression of L Fabp mRNA in intestine cells from the embryo 19 day to adult. The activity of L Fabp gene transcription was significantly higher at postnatal 2 day than other days,which proved to be rapid differentiation stage of intestine stem cells.p21 gene transcriptions and translations could hardly be detected from the stages of embryo to adult. In the meantime,the change of p53 gene transcription was not distinct,but its translations were gradually increased during the period of embryo 14 day to postnatal 2 day. The expression signal of p53 protein was negative after postnatal 7 day.Conclusion During the rapid differentiation stages of intestinal stem cells,the high expression of p53 protein might be the reason that protein half life is prolonged as a result of an accumulation of p53 protein,which is not associated with its transcription. It indicates that protein stability might be important for controlling p53 function. On the other hand,the mechanism of p53 regulating the differentiation of stem cells is not correlated with p21 pathway.