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目的 探讨丁酸钠 (NaBu)对细胞周期检测点效应及对U937细胞凋亡的敏感性。方法以U937 ASPI3K(ATM阴性 )、U937 pZeosv2 (+) (野生型ATM基因 )两种U937的变异细胞系作为细胞模型。用免疫沉淀及激酶活性测定p38MAPK、ERK1的激酶活性。用免疫印迹分析Bad磷酸化灭活。结果 经NaBu预处理的U937 pZeosv2 (+)细胞经13 7Cs照射后 ,细胞凋亡敏感性呈NaBu剂量依赖性增强。这种增强效应可被p38MAPK阻滞剂OLM阻断 ,但不能被p34cdc2激酶的特异性抑制剂ALP及CDK2阻滞剂CDK2 Ⅰ阻断。经NaBu预处理的U937 ASPI3K细胞经13 7Cs照射后 ,细胞凋亡敏感性进一步增强 ,这种增强效应可被OLM阻断。放射线可显著增强p38MAPK激酶活性 ,抑制ERK1激酶活性 ;NaBu预处理与放射线联用后 ,对p38MAPK激酶活性的增强有极其显著的协同效应。放射线诱导U937 ASPI3K细胞Bad蛋白磷酸化灭活 ,在NaBu协同作用下 ,Bad蛋白磷酸化灭活效应进一步增强。结论 NaBu通过p38MAPK激酶活性 ,增强细胞凋亡敏感性 ,该效应与ATM基因是否缺失无关 ,与ATM失活增强的细胞凋亡敏感性各为独立通路
Objective To investigate the effect of sodium butyrate (NaBu) on cell cycle checkpoint and its sensitivity to U937 cell apoptosis. Methods U937 ASPI3K (ATM negative), U937 pZeosv2 (+) (wild-type ATM gene) two mutant cell lines U937 as a cell model. The kinase activity of p38 MAPK and ERK1 was determined by immunoprecipitation and kinase activity. Bad phosphorylation was inactivated by Western blot analysis. Results NaBu pretreatment of U937 pZeosv2 (+) cells by 13 7Cs irradiation, the apoptosis-sensitive NaBu dose-dependent increase. This enhancement effect was blocked by the p38 MAPK inhibitor OLM, but not by the specific inhibitor of p34cdc2 kinase ALP and the CDK2 blockers. After NaBu-pretreated U937 ASPI3K cells were irradiated by137Cs, the apoptosis sensitivity was further enhanced, and this enhancement effect could be blocked by OLM. Radiation can significantly enhance p38MAPK kinase activity, inhibit ERK1 kinase activity; NaBu pretreatment and radiation combination, the p38MAPK kinase activity enhancement has a very significant synergistic effect. Radiation-induced phosphorylation of Bad protein in U937 ASPI3K cells was inactivated. The synergistic effect of NaBu resulted in further inhibition of the phosphorylation of Bad protein. Conclusion NaBu enhances the sensitivity of apoptosis through the p38MAPK kinase activity. This effect is independent of whether ATM gene is deleted or not, and the apoptosis sensitivity enhanced by ATM inactivation is independent of each other