Nox4-dependent activation of cofilin mediates VSMC reorientation in response to cyclic stretching.
Nox4-dependent activation of cofilin mediates VSMC reorientation in response to cyclic stretching.
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DOI：
10.1016/j.freeradbiomed.2015.05.011
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发表时间：
2015-08
影响因子：
7.4
通讯作者：
San Martín A
中科院分区：
文献类型：
--
作者：
Montenegro MF;Valdivia A;Smolensky A;Verma K;Taylor WR;San Martín A
血管平滑肌细胞(VSMCs)在血管壁内受到不同类型的机械力。虽然已知VSMC在机械刺激下进行细胞体重新定位，但这种机械拉伸如何在细胞内转化为导致细胞骨架重组的生化信号仍不清楚。Cofilin是一种控制肌动蛋白动态的蛋白质，通过氧化还原依赖的机制被Slingshot磷酸酶依赖的丝氨酸3去磷酸化激活。NOX4是血管壁中与细胞骨架结合的活性氧物种(ROS)的主要来源。因此，我们假设NOX4介导氧化还原依赖的cofilin的激活，这是机械刺激后细胞骨架重组和细胞重定位所必需的。在这项研究中，我们发现机械拉伸刺激VSMC产生ROS，导致细胞重新定位的信号需要过氧化氢，而不是超氧化物。事实上，机械拉伸诱导粘连蛋白激活和拉伸诱导的细胞骨架重组，并在粘连蛋白活性下调的细胞中抑制细胞重定向。重要的是，NOX4缺陷细胞不能激活粘连蛋白，也不能进行细胞重定向，这种表型可以通过表达一个结构性的活性粘连蛋白突变体来挽救。我们的结果表明，在VSMC中，机械刺激通过依赖NOX4的机制激活cofilin，这一途径是细胞骨架重组和细胞重新定位所必需的。
Vascular smooth muscle cells (VSMCs), are subjected to different types of mechanical forces within the vessel wall. Although it is known that VSMC undergo cell body reorientation in response to the mechanical stimulation, how this mechanical stretch is transduced within the cell into biochemical signals causing cytoskeleton reorganization remains unclear. Cofilin, a protein that controls actin dynamics, is activated by Slingshot phosphatase-dependent Serine 3 dephosphorylation by redox dependent mechanisms. Nox4 is a main source of reactive oxygen species (ROS) in the vessel wall that localizes in association with the cytoskeleton. Therefore, we hypothesize that Nox4 mediates redox-dependent activation of cofilin which is required for cytoskeletal reorganization and cell reorientation after mechanical stimulation. In this study, we found that mechanical stretch stimulates ROS production in VSMCs and that the signaling that leads to cell reorientation required hydrogen peroxide but not superoxide. Indeed, mechanical stretch induces cofilin activation and stretch-induced cytoskeletal reorganization and cell reorientation is inhibited in cells where cofilin activity has been downregulated. Importantly, Nox4 deficient cells fail to activate cofilin and to undergo cell reorientation, a phenotype rescued by expression of a constitutive active cofilin mutant. Our results demonstrate that in VSMC mechanical stimulation activates cofilin by a Nox4-dependent mechanism and that this pathway is required for cytoskeleton reorganization and cell reorientation.