Piech-Dumas K M, Best J A, Chen Y, Nagamoto-Combs K, Osterhout C A, Tank A W
Department of Pharmacology and Physiology, and the Neuroscience Program, University of Rochester Medical Center, Rochester, New York, USA.
J Neurochem. 2001 Mar;76(5):1376-85. doi: 10.1046/j.1471-4159.2001.00127.x.
Tyrosine hydroxylase (TH) gene promoter activity is increased in PC12 cells that are treated with the phorbol ester, 12-O-tetradecanoylphorbol 13-acetate (TPA). Mutagenesis of either the cAMP responsive element (CRE) or the activator protein-1 element (AP1) within the TH gene proximal promoter leads to a dramatic inhibition of the TPA response. The TH CRE and TH AP1 sites are also independently responsive to TPA in minimal promoter constructs. TPA treatment results in phosphorylation of cAMP responsive element binding protein (CREB) and activation of cAMP-dependent protein kinase (PKA) in PC12 cells; hence, we tested whether CREB and/or PKA are essential for the TPA response. In CREB-deficient cells, the response of the full TH gene proximal promoter or the independent response of the TH CRE by itself to TPA is inhibited. The TPA-inducibility of TH mRNA is also blocked in CREB-deficient cells. Expression of the PKA inhibitor protein, PKI, also inhibits the independent response of the TH CRE to TPA. Our results support the hypothesis that TPA stimulates the TH gene promoter via signaling pathways that activate either the TH AP1 or TH CRE sites. Both signaling pathways are dependent on CREB and the TH CRE-mediated pathway is dependent on PKA.
用佛波酯12 - O -十四烷酰佛波醇13 -乙酸酯（TPA）处理PC12细胞后，酪氨酸羟化酶（TH）基因启动子活性增强。TH基因近端启动子内的环磷酸腺苷反应元件（CRE）或激活蛋白-1元件（AP1）发生诱变会导致TPA反应受到显著抑制。在最小启动子构建体中，TH CRE和TH AP1位点也可独立对TPA作出反应。TPA处理导致PC12细胞中环磷酸腺苷反应元件结合蛋白（CREB）磷酸化以及环磷酸腺苷依赖性蛋白激酶（PKA）激活；因此，我们测试了CREB和/或PKA对TPA反应是否必不可少。在CREB缺陷型细胞中，完整的TH基因近端启动子的反应或TH CRE自身对TPA的独立反应均受到抑制。CREB缺陷型细胞中TH mRNA的TPA诱导性也被阻断。PKA抑制蛋白PKI的表达也抑制了TH CRE对TPA的独立反应。我们的结果支持这样的假说，即TPA通过激活TH AP1或TH CRE位点的信号通路刺激TH基因启动子。这两条信号通路均依赖于CREB，且TH CRE介导的通路依赖于PKA。
