人p53不同突变体的构建、表达及其对亚砷酸盐诱导细胞凋亡的影响

目的 构建人p53的不同突变体,并在真核细胞中表达,研究这些突变体对应激刺激诱导细胞凋亡的影响.方法 采用PCR方法扩增人p53 cDNA序列,使用常规酶切、连接方法将其重组至pcDNA3/HA载体中,对阳性克隆进行酶切和PCR鉴定.将阳性重组体的第15位和第46位丝氨酸突变为丙氨酸,并转染NIH3T3细胞,观察其在NIH3T3细胞内的表达情况.转染不同突变体的NIH3T3细胞用Annexin V-FITC和碘化丙啶双标后,利用流式细胞术检测亚砷酸盐刺激前后的凋亡情况.结果 构建的pcDNA3/HA-p53(WT)、pcDNA3/HA-p53(S15A)peDNA3/I-IA-p53(S46A)是正确的,且能在NIH3T3细胞内有效表达.流式细胞术检测表明,p53(WT)的表达使亚砷酸盐诱导的细胞凋亡增加,p53(S15A)的表达使细胞凋亡减少.而p53(S46A)没有明显影响.结论 p53的第15位丝氨酸在其介导亚砷酸盐诱导的细胞凋亡中具有重要作用.

Construction and expression of different mutants of human p53 and their effects on arsenite-induced cell apoptosis

OBJECTIVE: To construct different mutants of human p53 for expression in eukaryotic cells and investigate the effects of these mutants on stress-induced cell apoptosis. METHODS: Human p53 cDNA was amplified by PCR and cloned into pcDNA3/HA vector following the routine procedures. The Ser15 and Ser46 of p53 were mutated to Ala and identified by enzyme digestion and PCR, and these mutants were expressed in NIH3T3 cells and detected by Western blotting. After transfection with the plasmids of different p53 mutants, the NIH3T3 cells were double-stained with AnnexinV-FITC and propidium iodide for apoptotic analysis using flow cytometry. RESULTS: The recombinant plasmids of HA-tagged wild-type p53, HA-p53(WT), and its mutants, HA-p53(S15A) and HA-p53(S46A), were successfully constructed and expressed efficiently in NIH3T3 cells. The apoptotic ratio of p53(WT)-transfected cells induced by arsenite increased and that of p53(S15A)-transfected cells decreased significantly after arsenite stimulation, but no significant changes occurred in the apoptosis of p53(S46A)-transfected cells. CONCLUSION: The phosphorylation on Ser15 of p53 plays an important role in mediating arsenite-induced cell apoptosis.