肝细胞缺氧预处理细胞保护作用中热休克蛋白70表达的调控机制

Induction of HSP70 during hepatocyte hypoxic preconditioning

目的 研究热休克蛋白 70 (HSP70 )表达与肝细胞缺氧预处理的关系及其调控机制。方法 建立肝细胞缺氧预处理模型 ,应用蛋白激酶C(PKC)抑制剂、激动剂和丝裂原激活的蛋白激酶 (MEK)的抑制剂 ,通过检测PKC磷酸化水平、p44 /4 2丝裂原激活蛋白激酶 (p44 /4 2MAPKs)、HSP70表达量、细胞存活率 ,同时在透射电镜下观察肝细胞超微结构改变 ,研究缺氧预处理与HSP70表达的关系及HSP70表达的影响因素。对相关数据进行统计学处理。结果 和缺氧复氧组 (HR)比较 ,预处理组 (HP)和PKC激动剂组的HSP70和 p44 /4 2MAPKs的表达量显著增加 ,同时PKC磷酸化水平显著增高 ,三者分别为每分钟 (4 2 .63± 4.73 )、(10 9.42± 16.0 9)、(15 2 .47± 19.5 9)pmol/g(P均 <0 .0 1) ,肝细胞结构改变较小 ;和缺氧预处理组相比 ,PKC抑制剂组相应的观察指标呈相反的变化 ,PKC磷酸化活性显著降低 ,为每分钟 (65 .2 8± 5 .3 6) pmol/g(P <0 .0 1) ;MEK抑制剂组HSP70表达量和磷酸化激活的p44 /4 2MAPKs表达量降低 ,肝组织细胞结构出现较明显的改变。结论 效应保护蛋白HSP70在缺氧预处理中参与对肝细胞的保护 ,HSP70受到PKC介导p44 /4 2MAPKs信号通路的调控。PKC处在p44 /4 2MAPKs上游 ,PKC对 p44 /4 2MAPKs起正性调控作用 ;p44 /4

Objective To investigate the relationship between the expression of HSP70 and hypoxic preconditioning (HP) and the modulatory mechanism.Methods A normal liver cell HP model was established.PKC inhibitor,activator and MEK inhibitor were utilized to analyze the phosphorylation of PKC.The expression of p44/42 MAPKs and HSP70,viability,and cellular ultrastructure were also observed.All the data were statistically analyzed.Results Compared with the HR group,the expression of HSP70 and p44/42 MAPKs and the phosphorylation of PKC were obviously increased in HP group and PKC activated group.The phosphorylation of PKC was (42.63±4.73) pmol/g in HR group,(109.42±16.09) pmol/g in HP group and (152.47±19.59) pmol/g in PKC activated model (P<0.01).Compared with HP group,opposite changes were found in PKC or MEK inhibited group and the phosphorylation of PKC was decreased in PKC inhibited group (65.28±5.36) pmol/g (P<0.01).Conclusion HSP70 is involved in the cytoprotection of liver cells in hypoxic preconditioning.HSP70 is regulated by PKC dependent p44/42 MAPKs signal transduction pathway.