Brindle P, Nakajima T, Montminy M
Clayton Foundation Laboratories for Peptide Biology, Salk Institute, La Jolla, CA 92037, USA.
Proc Natl Acad Sci U S A. 1995 Nov 7;92(23):10521-5. doi: 10.1073/pnas.92.23.10521.
The second messenger cAMP stimulates the expression of numerous genes via the protein kinase A-mediated phosphorylation of the cAMP response element-binding protein (CREB) at Ser-133. Ser-133 phosphorylation, in turn, appears to induce target gene expression by promoting interaction between CREB and CBP, a 265-kDa nuclear phospho-CREB-binding protein. It is unclear, however, whether Ser-133 phosphorylation per se is sufficient for CREB-CBP complex formation and for target gene induction in vivo. Here we examine CREB activity in Jurkat T cells after stimulation of the T-cell receptor (TCR), an event that leads to calcium entry and diacylglycerol production. Triggering of the TCR stimulated Ser-133 phosphorylation of CREB with high stoichiometry, but TCR activation did not promote CREB-CBP complex formation or target gene induction unless suboptimal doses of cAMP agonist were provided as a costimulus. Our results demonstrate that, in addition to mediating Ser-133 phosphorylation of CREB, protein kinase A regulates additional proteins that are required for recruitment of the transcriptional apparatus to cAMP-responsive genes.
第二信使环磷酸腺苷（cAMP）通过蛋白激酶A介导的环磷酸腺苷反应元件结合蛋白（CREB）在丝氨酸133位点的磷酸化作用，刺激众多基因的表达。反过来，丝氨酸133位点的磷酸化似乎通过促进CREB与CBP（一种265 kDa的核磷酸化CREB结合蛋白）之间的相互作用来诱导靶基因表达。然而，目前尚不清楚丝氨酸133位点的磷酸化本身是否足以在体内形成CREB - CBP复合物并诱导靶基因表达。在这里，我们检测了T细胞受体（TCR）刺激后Jurkat T细胞中的CREB活性，TCR刺激会导致钙离子内流和二酰基甘油的产生。TCR的激活以高化学计量比刺激了CREB的丝氨酸133位点磷酸化，但除非提供次优剂量的cAMP激动剂作为共刺激，否则TCR激活不会促进CREB - CBP复合物的形成或靶基因诱导。我们的结果表明，除了介导CREB的丝氨酸133位点磷酸化外，蛋白激酶A还调节将转录装置募集到cAMP反应基因所需的其他蛋白质。
