Wu Jian-Min, Xiao Lei, Cheng Xiao-Kuan, Cui Lian-Xian, Wu Ning-Hua, Shen Yu-Fei
National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China.
J Biol Chem. 2003 Dec 19;278(51):51143-9. doi: 10.1074/jbc.M305537200. Epub 2003 Oct 6.
An early event in cellular heat shock response is the transmittance of stress signals from the cell surface into the nuclei, resulting in the induction of heat shock proteins (Hsps). Protein kinase C (PKC) has been implicated as a key player in transducing stress signals. However, mechanism(s) by which PKC regulates heat shock-induced events remains largely unknown. Here we present data that pan-PKC inhibitor GF109203X, but not classic PKC inhibitor Gö6976, specifically repressed heat shock-induced accumulation of mRNA as well as promoter activity of hsp90 beta, but not hsp90 alpha, in Jurkat cells. Subcellular fractionation studies revealed that heat shock exclusively induced PKC-epsilon membrane translocation. Consistently, expression of a constitutively active PKC-epsilon(A159E) resulted in an enhanced promoter activity of hsp90 beta upon heat shock, whereas a dominant-negative PKC-epsilon(K437R) abolished this effect. In contrast, constitutively active-PKC-alpha or dominant-negative-PKC-alpha had no effects on heat shock induction of the gene. The effect of PKC-epsilon on hsp90 beta expression seems to be stimuli-specific, as phorbol myristate acetate-mediated hsp90 beta expression was PKC-epsilon-independent. We conclude that PKC-epsilon is specifically required in the signaling pathway leading to the induction of hsp90 beta gene in response to heat shock.
细胞热休克反应的早期事件是应激信号从细胞表面传递到细胞核，从而诱导热休克蛋白（Hsps）的产生。蛋白激酶C（PKC）被认为是转导应激信号的关键因子。然而，PKC调节热休克诱导事件的机制在很大程度上仍然未知。在此，我们展示的数据表明，泛PKC抑制剂GF109203X而非经典PKC抑制剂Gö6976，特异性地抑制了热休克诱导的mRNA积累以及Jurkat细胞中hsp90β而非hsp90α的启动子活性。亚细胞分级分离研究表明，热休克仅诱导PKC-ε向膜的转位。一致地，组成型活性PKC-ε（A159E）的表达导致热休克时hsp90β的启动子活性增强，而显性负性PKC-ε（K437R）则消除了这种效应。相比之下，组成型活性PKC-α或显性负性PKC-α对该基因的热休克诱导没有影响。PKC-ε对hsp90β表达的影响似乎具有刺激特异性，因为佛波酯肉豆蔻酸酯介导的hsp90β表达不依赖于PKC-ε。我们得出结论，PKC-ε在响应热休克诱导hsp90β基因的信号通路中是特异性必需的。
