Helmbrecht K, Rensing L
Institute of Cell Biology, Biochemistry and Biotechnology, University of Bremen, Germany.
Neurochem Res. 1999 Oct;24(10):1293-9. doi: 10.1023/a:1020933308947.
Analysis of constitutive heat shock protein 70 (HSC70) concentration in unstressed proliferating and differentiated rat C6 glioma cells revealed a striking reduction in the amount of HSC70 in differentiated cells. Proliferating cells showed a significantly higher HSC70 concentration, particularly observable during S phase in synchronous cultures. The activity of the cAMP/PKA signaling pathway was enhanced in differentiated cells. cAMP-elevating treatments both inhibited growth and reduced HSC70 concentration. Inactivation of PKA by H-89 upregulated the reduced HSC70 expression in differentiated cells and stimulated proliferation. Treatment with an inhibitor of MAP kinase activation (PD98059) reduced the HSC70 concentration. We assume that cAMP does not directly inhibit HSC70 expression by transcriptional repression, but by its inhibitory effect on the MAP kinase pathway.
对未受应激的增殖和分化大鼠C6胶质瘤细胞中组成型热休克蛋白70（HSC70）浓度的分析显示，分化细胞中HSC70的量显著减少。增殖细胞显示出明显更高的HSC70浓度，在同步培养的S期尤为明显。分化细胞中cAMP/PKA信号通路的活性增强。提高cAMP的处理既抑制生长又降低HSC70浓度。H-89使PKA失活上调了分化细胞中降低的HSC70表达并刺激增殖。用丝裂原活化蛋白激酶激活抑制剂（PD98059）处理降低了HSC70浓度。我们假设cAMP不是通过转录抑制直接抑制HSC70表达，而是通过其对丝裂原活化蛋白激酶途径的抑制作用。
