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为了探讨候选肝癌抑癌蛋白PIG11(p53-induced gene11,PIG11)诱导细胞凋亡的机制,首次在HepG2细胞株中鉴定了11个PIG11结合蛋白,热休克蛋白60(heat shock protein60,Hsp60)为其中之一.采用免疫共沉淀联合Western blot技术对Hsp60进行了验证.用Western blot检测其蛋白质表达,结果显示:pLXSN-PIG11-HepG2细胞中Hsp60蛋白表达较pLXSN-HepG2、HepG2细胞组下调(n=3,P<0.01).选取与Hsp60关系密切的Bax蛋白进行研究,Western blot结果显示PIG11高表达可引起胞浆Bax向线粒体转位.以上结果表明,PIG11蛋白能与HepG2细胞中的Hsp60结合,促进Hsp60-Bax的分离,引起Bax从胞液到线粒体转位,激活线粒体凋亡途径,这可能是其诱导HepG2细胞凋亡的主要机制之一.
To investigate the mechanism of apoptosis induced by candidate PIG11, eleven PIG11-binding proteins were identified in HepG2 cell line for the first time. Heat shock protein60 (Hsp60) Hsp60 was verified by co-immunoprecipitation combined with Western blot.Western blot was used to detect the protein expression of Hsp60.The results showed that the expression of Hsp60 in pLXSN-PIG11-HepG2 cells was down-regulated compared with pLXSN-HepG2 and HepG2 cells (n = 3, P <0.01) .Selecting the Bax protein closely related to Hsp60, Western blot results showed that PIG11 overexpression could induce the translocation of Bax to mitochondria in cytoplasm.The above results show that PIG11 protein can bind to Hsp60 in HepG2 cells, Promote the separation of Hsp60-Bax, cause the translocation of Bax from cytosol to mitochondria, and activate the mitochondrial apoptotic pathway, which may be one of the main mechanisms that induce apoptosis of HepG2 cells.