Matrix Stiffness-Induced Myofibroblast Differentiation Is Mediated by Intrinsic Mechanotransduction
Matrix Stiffness-Induced Myofibroblast Differentiation Is Mediated by Intrinsic Mechanotransduction
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DOI：
10.1165/rcmb.2012-0050oc
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发表时间：
2012-09-01
影响因子：
6.4
通讯作者：
Zhou, Yong
中科院分区：
文献类型：
--
作者：
Huang, Xiangwei;Yang, Naiheng;Zhou, Yong
细胞外基质的机械性质最近已被证明可以促进肌成纤维细胞分化和肺纤维化。基质硬度调节肌成纤维细胞分化的机制还不完全清楚。本研究的目的是确定机械转导的内在机制，在基质硬度诱导的肌成纤维细胞分化的调节。在这项研究中使用了一个良好建立的聚丙烯酰胺凝胶系统与可调基板刚度。巨核细胞白血病因子-1（MKL 1）核转位通过共聚焦免疫荧光显微镜成像。通过定量染色质免疫沉淀试验定量MKL 1与α-平滑肌肌动蛋白（α-SMA）基因启动子的结合。正常人肺成纤维细胞对基质硬化的反应是肌动蛋白动力学的变化，有利于丝状肌动蛋白聚合。肌动蛋白聚合导致MKL 1的核转位，MKL 1是一种血清反应因子共激活因子，在调节纤维化基因（包括肌成纤维细胞分化的标志物α-SMA）表达中起核心作用。Mkl 1缺陷的小鼠肺成纤维细胞对α-SMA表达增加的基质硬化没有反应，而人MKL 1 cDNA的异位表达恢复了Mkl 1缺失的肺成纤维细胞表达α-SMA的能力。此外，基质硬化促进了小GTdR RhoA的产生和活化，增加了Rho激酶（ROCK）活性，并增强了成纤维细胞的收缩性。抑制RhoA/ROCK废除了僵硬基质诱导的肌动蛋白细胞骨架重组，MKL 1核转位和肌成纤维细胞分化。这项研究表明，肌动蛋白细胞骨架重塑介导的激活MKL 1转导机械刺激从细胞外基质的纤维化程序，促进肌成纤维细胞分化，这表明一个内在的mechanotransduction机制。
The mechanical properties of the extracellular matrix have recently been shown to promote myofibroblast differentiation and lung fibrosis. Mechanisms by which matrix stiffness regulates myofibroblast differentiation are not fully understood. The goal of this study was to determine the intrinsic mechanisms of mechanotransduction in the regulation of matrix stiffness-induced myofibroblast differentiation. A well established polyacrylamide gel system with tunable substrate stiffness was used in this study. Megakaryoblastic leukemia factor-1 (MKL1) nuclear translocation was imaged by confocal immunofluorescent microscopy. The binding of MKL1 to the alpha-smooth muscle actin (alpha-SMA) gene promoter was quantified by quantitative chromatin immunoprecipitation assay. Normal human lung fibroblasts responded to matrix stiffening with changes in actin dynamics that favor filamentous actin polymerization. Actin polymerization resulted in nuclear translocation of MKL1, a serum response factor coactivator that plays a central role in regulating the expression of fibrotic genes, including alpha-SMA, a marker for myofibroblast differentiation. Mouse lung fibroblasts deficient in Mkl1 did not respond to matrix stiffening with increased alpha-SMA expression, whereas ectopic expression of human MKL1 cDNA restored the ability of Mkl1 null lung fibroblasts to express alpha-SMA. Furthermore, matrix stiffening promoted production and activation of the small GTPase RhoA, increased Rho kinase (ROCK) activity, and enhanced fibroblast contractility. Inhibition of RhoA/ROCK abrogated stiff matrix-induced actin cytoskeletal reorganization, MKL1 nuclear translocation, and myofibroblast differentiation. This study indicates that actin cytoskeletal remodeling-mediated activation of MKL1 transduces mechanical stimuli from the extracellular matrix to a fibrogenic program that promotes myofibroblast differentiation, suggesting an intrinsic mechanotransduction mechanism.