Akt and RhoA activation in response to high glucose require caveolin-1 phosphorylation in mesangial cells
Akt and RhoA activation in response to high glucose require caveolin-1 phosphorylation in mesangial cells
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DOI：
10.1152/ajprenal.00447.2013
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发表时间：
2014-06-01
影响因子：
4.2
通讯作者：
Zhang, Bai-Fang
中科院分区：
文献类型：
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作者：
Wu, Su-Zhen;Peng, Fang-Fang;Zhang, Bai-Fang
肾小球基质积聚是糖尿病肾病的标志。丝氨酸/苏氨酸激酶pkc - β 1介导葡萄糖诱导的Akt S473磷酸化、RhoA激活和转化生长因子(TGF)- β 1上调，最终导致系膜细胞（MCs）基质上调。据报道，葡萄糖诱导的pkc - β 1激活依赖于MCs中小窝蛋白-1和完整小窝的存在；然而，激活的pkc - β 1是否调节caveolin-1的表达和磷酸化尚不清楚。在这里，我们发现，尽管小窝蛋白-1蛋白水平没有明显变化，pkc - β特异性抑制剂LY-333531阻断了高糖（HG）处理的MCs和糖尿病大鼠肾皮质中小窝蛋白-1 Y14的磷酸化。Src特异性抑制剂SU-6656阻止了hc诱导的pkc - β 1与caveolin-1和pkc - β 1膜易位之间的关联，而pkc - β 1小干扰RNA未能阻止Src激活，表明Src激酶在pkc - β 1激活的上游。虽然LY-333531阻断了pkc - β 1的膜易位，但对pkc - β 1/ caveolin-1的关联没有影响，提示pkc - β 1的激活需要caveolin-1和pkc - β 1的相互作用。SU-6656和不可磷酸化突变体caveolin-1 Y14A可阻止pkc - β 1介导的Akt S473磷酸化、RhoA激活和纤连蛋白上调对HG的响应。综上所述，HG激活Src介导pkc - β 1/caveolin-1的关联和pkc - β 1的激活，从而帮助Src激酶磷酸化caveolin-1 Y14。下游效应，包括Akt S473磷酸化、RhoA激活和纤维连接蛋白上调，需要caveolin- 1y14磷酸化。因此，小窝蛋白-1是糖尿病肾病中促纤维化过程的重要介质。
Glomerular matrix accumulationc is a hallmark of diabetic renal disease. Serine/threonine kinase PKC-beta 1 mediates glucose- induced Akt S473 phosphorylation, RhoA activation, and transforming growth factor (TGF)-beta 1 upregulation and finally leads to matrix upregulation in mesangial cells (MCs). It has been reported that glucose- induced PKC-beta 1 activation is dependent on caveolin-1 and the presence of intact caveolae in MCs; however, whether activated PKC-beta 1 regulates caveolin-1 expression and phosphorylation are unknown. Here, we showed that, although the caveolin-1 protein level had no significant change, the PKC-beta-specific inhibitor LY-333531 blocked caveolin-1 Y14 phosphorylation in high glucose (HG)-treated MCs and in the renal cortex of diabetic rats. The Src-specific inhibitor SU-6656 prevented the HG-induced association between PKC-beta 1 and caveolin-1 and PKC-beta 1 membrane translocation, whereas PKC-beta 1 small interfering RNA failed to block Src activation, indicating that Src kinase is upstream of PKC-beta 1 activation. Although LY-333531 blocked PKC-beta 1 membrane translocation, it had no effect on the PKC-beta 1/ caveolin-1 association, suggesting that PKC-beta 1 activation requires the interaction of caveolin-1 and PKC-beta 1. PKC-beta 1-mediated Akt S473 phosphorylation, RhoA activation, and fibronectin upregulation in response to HG were prevented by SU-6656 and nonphosphorylatable mutant caveolin-1 Y14A. In conclusion, Src activation by HG mediates the PKC-beta 1/caveolin-1 association and PKC-beta 1 activation, which assists in caveolin-1 Y14 phosphorylation by Src kinase. The downstream effects, including Akt S473 phosphorylation, RhoA activation, and fibronectin upregulation, require caveolin- 1 Y14 phosphorylation. Caveolin-1 is thus an important mediator of the profibrogenic process in diabetic renal disease.