【摘要】 探讨了佛波酯 ( phorbol 12 myristate 13 acetate,PMA)对人肺癌表皮细胞株A 5 4 9细胞中数种蛋白激酶C(proteinkinaseC ,PKC)亚型的调节作用。用蛋白质免疫印迹法在A 5 4 9细胞中检测到有PKC α、PKC βII、PKC γ、PKC δ和PKC ε等亚型的表达 ,但未检测到PKC ζ的表达。PMA对细胞的短时间处理诱导所有这 5种亚型的不同程度的转位 (即活化 )。长时间处理则显著下调PKC α、PKC γ、PKC δ和PKC ε的蛋白质水平 ,但PKC βII的蛋白质水平却不受影响。此外 ,PMA长时间处理细胞对同一PKC亚型在膜组分和胞液组分中的蛋白质水平表现出不同的调节作用。PMA长时间处理导致胞液组分中的PKC δ和PKC γ水平显著的下降 ,并引起PKC α和PKC βII的消失或耗空 ;然而 ,对细胞膜组分中这些PKC亚型的蛋白质水平却没有明显的影响。PMA长时间处理对胞液和胞膜组分中的PKC ε水平的下调作用均十分明显。以上的观察为PMA在活化与下调不同PKC亚型中的作用提供了新的证据 ,有助于增加对细胞内PKC的活化及水平的变化在化学致癌过程中的作用的了解更多还原

【Abstract】 Protein kinase C, a family of serine threonine pro te in kinases, mediates a variety of intracellular signaling events. Here, the regu latory effect of phorbol 12 myristate 13 acetate(PMA)on the several PKC isozym es in the human lung carcinoma cells A 549 was studied. The expression of PKC α?PKC βII?PKC γ?PKC δ and PKC ε in A 549 cells was examined. No det ectable PKC ζ was observed. Short term treatment of cells with PMA led to the translocation of these PKC isozymes, to different extent, from cytosol to cell membrane. Whereas, prolonged treatment of cells with PMA pronouncedly reduced th e levels of PKC α?PKC γ?PKC δ and PKC ε, but the intracellular level o f PKC βII was not affected. Furthermore, PMA was observed to have differential effects on the down regulation of PKC isozymes located in the cytosol and of t hose located in the membrane. Prolonged PMA treatment caused extensive decrease in the levels of cytosolic PKC δ and PKC γ, and depleted cytosolic PKC α a nd PKC βII. However, the amount levels of membrane PKC α?PKC βII?PKC γ ?PKC δ isozymes were not decreased. In contrast, PKC ε in both cytosol and membrane fraction was obviously down regulated by prolonged PMA treatment. This study provided novel evidence on the PMA mediated activation and down regulat ion of different PKC isozymes, which might be helpful in deepening our understan ding on the roles of PKC activation and the alterations of their intracellular l evels in processes of chemical carcinogenesis.更多还原