Kitagawa M, Mukai H, Takahashi M, Ono Y
Graduate School of Science and Technology, Faculty of Science, Kobe, 657-8501, Japan.
Biochem Biophys Res Commun. 1998 Nov 27;252(3):561-5. doi: 10.1006/bbrc.1998.9694.
We previously reported that PKN, a fatty acid-activated serine/threonine protein kinase, translocates from the cytosol to the nucleus by stresses such as heat shock, sodium arsenite, and serum starvation. To clarify the role of PKN under heat stress, we examined whether PKN regulates the expression of heat shock proteins. Co-expression of heat shock transcription factor 1 (HSF1) and the catalytically active fragment of PKN induced the accumulation of alphaB-crystallin but not HSP27 and HSP70 in HeLa S3 cells. The expression of the reporter gene for alphaB-crystallin promoter was activated by co-expression of HSF1 and the catalytically active fragment of PKN, and this activation was dependent on the protein kinase activity of PKN. Deletion analysis of the alphaB-crystallin promoter region revealed that both the proximal and the distal heat shock elements were necessary for the transactivation. These results raise the possibility that there is a signal transduction pathway mediating stress signals for the accumulation of alphaB-crystallin by HSF1 and PKN.
我们之前报道过，PKN是一种脂肪酸激活的丝氨酸/苏氨酸蛋白激酶，在热休克、亚砷酸钠和血清饥饿等应激条件下会从细胞质转移至细胞核。为阐明PKN在热应激下的作用，我们检测了PKN是否调控热休克蛋白的表达。在HeLa S3细胞中，热休克转录因子1（HSF1）与PKN的催化活性片段共表达可诱导αB-晶状体蛋白的积累，但不会诱导HSP27和HSP70的积累。αB-晶状体蛋白启动子的报告基因表达通过HSF1与PKN的催化活性片段共表达而被激活，且这种激活依赖于PKN的蛋白激酶活性。对αB-晶状体蛋白启动子区域的缺失分析表明，近端和远端热休克元件对于反式激活均是必需的。这些结果提示，可能存在一条信号转导途径，介导应激信号，促使HSF1和PKN诱导αB-晶状体蛋白积累。
