Mechanistic differences in the activation of estrogen receptor-α (ERα)- and ERβ-dependent gene expression by cAMP signaling pathway(s)
Mechanistic differences in the activation of estrogen receptor-α (ERα)- and ERβ-dependent gene expression by cAMP signaling pathway(s)
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DOI：
10.1074/jbc.m212312200
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发表时间：
2003-04-11
影响因子：
4.8
通讯作者：
Smith, CL
中科院分区：
文献类型：
--
作者：
Coleman, KM;Dutertre, M;Smith, CL
虽然在没有外源性激素的情况下，细胞内cAMP的增加可以刺激雌激素受体α（ER α）的活性，但没有研究表明ER β是否可以类似地调节。在瞬时转染，毛喉素加3-异丁基-1-甲基黄嘌呤（IBMX），增加细胞内cAMP，刺激ER α和ER β的转录活性。这种作用被蛋白激酶A抑制剂H89（N-（2-（p-bromocinnamamino）-ethyl）-5-isoquinolinesulfonamide）阻断，并且依赖于雌激素反应元件。位于雌激素反应元件5'端的12-O-十四烷酰基佛波醇-13-乙酸酯反应元件（TRE）是cAMP依赖性ER β而非ER α激活基因表达所必需的，表明前一亚型需要与TRE相互作用因子的功能性相互作用来刺激转录。p160和CREB结合蛋白共激活物均刺激cAMP诱导的ER α和ER β转录活性。然而，突变的两个cAMP诱导的SRC-1磷酸化位点的cAMP激活鸡孕酮受体或所有七个已知的SRC-1磷酸化位点的重要性，并没有特别损害cAMP激活ER α。ER α的E/F结构域足以被毛喉素/IBMX激活，并且这伴随着受体磷酸化的增加。相比之下，cAMP信号转导减少了ER β相应区域的磷酸化，这与缺乏毛喉素/IBMX刺激的转录活性相关。我们的数据表明，cAMP激活ER α转录活性与受体而不是SRC-1磷酸化有关。此外，辅因子的要求，ER α和ER β的结构域足够的毛喉素/IBMX激活，和cAMP对受体磷酸化的影响的差异表明，这种信号通路利用不同的机制来刺激ER α和ER β的转录活性。
Although increases in intracellular cAMP can stimulate estrogen receptor-alpha (ERalpha) activity in the absence of exogenous hormone, no studies have addressed whether ERbeta can be similarly regulated. In transient transfections, forskolin plus 3-isobutyl-1-methylxanthine (IBMX), which increases intracellular cAMP, stimulated the transcriptional activities of both ERalpha and ERbeta. This effect was blocked by the protein kinase A inhibitor H89 (N-(2-(p-bromocinnamylamino)-ethyl)-5-isoquinolinesulfonamide) and was dependent on an estrogen response element. A 12-O-tetradecanoylphorbol-13-acetate response element (TRE) located 5' to the estrogen response element was necessary for cAMP-dependent activation of gene expression by ERbeta but not ERalpha, indicating that the former subtype requires a functional interaction with TRE-interacting factor(s) to stimulate transcription. Both p160 and CREB-binding protein coactivators stimulated cAMP-induced ERalpha and ERbeta transcriptional activity. However, mutation of the two cAMP-inducible SRC-1 phosphorylation sites important for cAMP activation of chicken progesterone receptor or all seven known SRC-1 phosphorylation sites did not specifically impair cAMP activation of ERalpha. The E/F domains of ERa are sufficient for activation by forskolin/IBMX, and this is accompanied by an increase in receptor phosphorylation. In contrast, cAMP signaling reduces the phosphorylation of the corresponding region of ERbeta, and this correlates with the lack of forskolin/IBMX stimulated transcriptional activity. Our data suggest that cAMP activation of ERalpha transcriptional activity is associated with receptor instead of SRC-1 phosphorylation. Moreover, differences in the cofactor requirements, domains of ERalpha and ERbeta sufficient for forskolin/IBMX activation, and the effect of cAMP on receptor phosphorylation indicate that this signaling pathway utilizes distinct mechanisms to stimulate ERalpha and ERbeta transcriptional activity.