Department of Agricultural Chemistry, Faculty of Agriculture, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, 156-8502, Tokyo, Setagaya, Japan.
Cytotechnology. 2005 Jan;47(1-3):107-16. doi: 10.1007/s10616-005-3763-6.
The cAMP and Ca(2+) signaling pathways activate the transcription factor CREB through its phosphorylation at Serine 133. Activation of CREB is involved in the regulation of various biological phenomena. To understand further the mechanisms of the regulation of CREB activity in response to activation of the cAMP and Ca(2+) signaling pathways, we examined the roles of PLCgammas in CREB activation in PC12 cells. siRNA-mediated reduction of the expression of PLCgamma2, but not PLCgamma1, inhibited both the phosphorylation of CREB at S133 and the activation of CREB-dependent transcription following treatment of cells with forskolin or ionomycin, which increases the intracellular concentrations of cAMP or Ca(2+), respectively. Importantly, the siRNA targeting PLCgamma2 completely abolished CREB activation by Ca(2+) signaling but not by cAMP signaling. These results suggest that PLCgamma2 functions as an essential signal transducer leading to CREB activation in response to activation of the Ca(2+) signaling pathway and that the cAMP signaling pathway might activate CREB through phosphorylation of CREB by PKA and another signaling pathway mediated by PLCgamma2.
cAMP 和 Ca(2+) 信号通路通过丝氨酸 133 位点的磷酸化激活转录因子 CREB。CREB 的激活参与了各种生物现象的调节。为了进一步了解 cAMP 和 Ca(2+) 信号通路激活时 CREB 活性调节的机制，我们研究了 PLCgammas 在 PC12 细胞中对 CREB 激活的作用。siRNA 介导的 PLCgamma2 表达减少，而不是 PLCgamma1，抑制了 forskolin 或离子霉素处理细胞后 CREB 在 S133 位点的磷酸化和 CREB 依赖性转录的激活，分别增加了细胞内 cAMP 或 Ca(2+) 的浓度。重要的是，靶向 PLCgamma2 的 siRNA 完全消除了 Ca(2+) 信号而不是 cAMP 信号对 CREB 激活的作用。这些结果表明，PLCgamma2 作为一种必需的信号转导分子，在 Ca(2+) 信号通路激活时导致 CREB 激活，而 cAMP 信号通路可能通过 PKA 对 CREB 的磷酸化和由 PLCgamma2 介导的另一种信号通路激活 CREB。
