AMP-activated protein kinase inhibits transforming growth factor-β-induced Smad3-dependent transcription and myofibroblast transdifferentiation
AMP-activated protein kinase inhibits transforming growth factor-β-induced Smad3-dependent transcription and myofibroblast transdifferentiation
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DOI：
10.1074/jbc.m800902200
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发表时间：
2008-04-18
影响因子：
4.8
通讯作者：
Simonson, Michael S.
中科院分区：
文献类型：
--
作者：
Mishra, Rangnath;Cool, Barbara L.;Simonson, Michael S.
在创伤愈合中，肌成纤维细胞转分化(MFT)是一种表型的化生改变，产生促纤维化效应细胞，分泌和重塑细胞外基质。与诱导MFT的途径不同，负面调节MFT的分子机制知之甚少。在这里，我们报告了AMP激活的蛋白激酶(AMPK)阻断MFT对转化生长因子-β(TGF-β)的反应。AMPK的药理激活可抑制转化生长因子β诱导的细胞外基质蛋白、I型和IV型胶原以及纤维连接蛋白的分泌。AMPK的激活也阻止了肌肉成纤维细胞表型标志物α-平滑肌肌动蛋白和ED-A纤维连接蛋白剪接变异体的诱导。AMPK激活剂不能阻止转导显性阴性、激酶死亡的AMPKα2腺病毒转导的细胞中的MFT。此外，AMPK激活剂也不能抑制AMPK(α1，2)(-/-)成纤维细胞的MFT诱导，这表明需要AMPKα的表达。腺病毒转导固有活性的AMPK(α2)足以阻止转化生长因子β诱导的I型胶原、α-平滑肌肌动蛋白和ED-A纤维连接蛋白。AMPK不能减少转化生长因子β刺激的Smad3 COOH末端的磷酸化和核转位，这是MFT所必需的。然而，AMPK的激活抑制了Smad3结合的顺式元件驱动的转化生长因子β诱导的转录。与AMPK在转录调控中的作用一致，AMPKα2的核转位与核内活性AMPKα的出现有关。综上所述，这些结果表明，AMPK抑制了转化生长因子β诱导的Smad3 COOH末端磷酸化下游的转录和核转位。此外，AMPK的激活足以在体外负向调节MFT。
In wound healing, myofibroblast transdifferentiation (MFT) is a metaplastic change in phenotype producing profibrotic effector cells that secrete and remodel the extracellular matrix. Unlike pathways that induce MFT, the molecular mechanisms that negatively regulate MFT are poorly understood. Here, we report that AMP-activated protein kinase (AMPK) blocks MFT in response to transforming growth factor-beta (TGF beta). Pharmacological activation of AMPK inhibited TGF beta-induced secretion of extracellular matrix proteins collagen types I and IV and fibronectin. AMPK activation also prevented induction of the myofibroblast phenotype markers alpha-smooth muscle actin and the ED-A fibronectin splice variant. AMPK activators did not prevent MFT in cells transduced with an adenovirus expressing dominant negative, kinase-dead AMPK alpha 2. Moreover, AMPK activators did not inhibit MFT induction in AMPK(alpha 1,2)(-/-) fibroblasts, demonstrating a requirement for AMPK alpha expression. Adenoviral transduction of constitutively active AMPK(alpha 2) was sufficient to prevent TGF beta-induced collagen I, alpha-smooth muscle actin, and ED-A fibronectin. AMPK did not reduce TGF beta-stimulated Smad3 COOH-terminal phosphorylation and nuclear translocation, which are necessary for MFT. However, AMPK activation inhibited TGF beta-induced transcription driven by Smad3-binding cis-elements. Consistent with a role for AMPK in transcriptional regulation, nuclear translocation of AMPK alpha 2 correlated with the appearance of active AMPK alpha in the nucleus. Collectively, these results demonstrate that AMPK inhibits TGF beta-induced transcription downstream of Smad3 COOH-terminal phosphorylation and nuclear translocation. Furthermore, activation of AMPK is sufficient to negatively regulate MFT in vitro.