β-adrenergic activation of p38 MAP kinase in adipocytes -: cAMP induction of the uncoupling protein 1 (UCP1) gene requires p38 MAP kinase
β-adrenergic activation of p38 MAP kinase in adipocytes -: cAMP induction of the uncoupling protein 1 (UCP1) gene requires p38 MAP kinase
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DOI：
10.1074/jbc.m101049200
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发表时间：
2001-07-20
影响因子：
4.8
通讯作者：
Collins, S
中科院分区：
文献类型：
--
作者：
Cao, WH;Medvedev, AV;Collins, S
由于越来越多的证据表明G蛋白偶联受体激活了多个信号通路，因此确定这些信号通路的协调性及其生理意义变得非常重要。在这里，我们表明，β(3)肾上腺素能受体(beta(3)AR)通过PKA刺激脂肪细胞中的p38丝裂原激活蛋白激酶(P38 MAPK)，并且β(3)AR依赖于cAMP转录线粒体解偶联蛋白1(UCP1)启动子需要p38 MAPK。选择性β(3)受体激动剂CL316,243(CL)以时间和剂量依赖的方式刺激白色和棕色脂肪细胞MAPK 3/6和p38MAPK的磷酸化，异丙肾上腺素和Forsklin模拟CL对p38MAPK的影响。在所有情况下，p38 MAPK特异性抑制剂SB202190(SB；1-10um)均可阻断激活。PKA抑制剂H89(20um)和(R-p)-cAMP-S(1 MM)阻断p38MAPK磷酸化的能力证实了PKA参与β(3)AR依赖的p38MAPK的激活。原代棕色脂肪细胞经CL或Forsklin处理后，UCP1mRNA表达水平升高(6.8-+/-0.8倍)，这种反应可被PKA抑制剂和SB202190消除。同样，CL和Forskolin对3.7kb的UCP1启动子的刺激也被PKA抑制剂和SB202190完全抑制，表明这些对UCP1表达的影响是转录的。此外，UCP1启动子依赖于PKA的反式激活以及其对SB202190的敏感性完全由UCP1基因的220个核苷酸增强子元件复制。我们同样观察到，CL促进ATF-2的磷酸化对H89和SB202190都敏感，而cAMP反应元件结合蛋白的磷酸化只被H89抑制。综上所述，这些研究表明，p38MAPK是脂肪细胞β-肾上腺素能/cAMP/PKA信号通路的重要下游靶点，而这一级联反应的功能结果之一是刺激棕色脂肪细胞中UCP1基因的表达。
Because of increasing evidence that G protein-coupled receptors activate multiple signaling pathways, it becomes important to determine the coordination of these pathways and their physiological significance. Here we show that the beta (3)-adrenergic receptor (beta (3)AR) stimulates p38 mitogen-activated protein kinase (p38 MAPK) via PKA in adipocytes and that cAMP-dependent transcription of the mitochondrial uncoupling protein 1 (UCP1) promoter by beta (3)AR requires p38 MAPK. The selective beta (3)AR agonist CL316,243 (CL) stimulates phosphorylation of MAP kinase kinase 3/6 and p38 MAPK in a time- and dose-dependent manner in both white and brown adipocytes, Isoproterenol and forskolin mimicked the effect of CL on p38 MAPK. In all cases activation was blocked by the specific p38 MAPK inhibitor SB202190 (SB; 1-10 muM). The involvement of PKA in beta (3)AR-dependent p38 MAPK activation was confirmed by the ability of the PKA inhibitors H89 (20 muM) and (R-p)-cAMP-S (1 mM) to block phosphorylation of p38 MAPK. Treatment of primary brown adipocytes with CL or forskolin induced the expression of UCP1 mRNA levels (6.8- +/- 0.8-fold), and this response was eliminated by PKA inhibitors and SB202190. A similar stimulation of a 3.7-kilobase UCP1 promoter by CL and forskolin was also completely inhibited by PKA inhibitors and SB202190, indicating that these effects on UCP1 expression are transcriptional. Moreover, the PKA-dependent transactivation of the UCP1 promoter, as well as its sensitivity to SB202190, was fully reproduced by a 220-nucleotide enhancer element from the UCP1 gene. We similarly observed that increased phosphorylation of ATF-2 by CL was sensitive to both H89 and SB202190, while phosphorylation of cAMP-response element-binding protein was inhibited only by H89. Together, these studies illustrate that p38 MAPK is an important downstream target of the beta -adrenergic/cAMP/PKA signaling pathway in adipocytes, and one of the functional consequences of this cascade is stimulation of UCP1 gene expression in brown adipocytes.