Contractile activity and smooth muscle α-actin organization in thrombin-induced human lung myofibroblasts
Contractile activity and smooth muscle α-actin organization in thrombin-induced human lung myofibroblasts
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DOI：
10.1152/ajplung.00417.2002
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发表时间：
2003-08-01
影响因子：
4.9
通讯作者：
Ludwicka-Bradley, A
中科院分区：
文献类型：
--
作者：
Bogatkevich, GS;Tourkina, E;Ludwicka-Bradley, A
活化的成纤维细胞，或肌成纤维细胞，在组织重塑、伤口愈合和各种纤维化疾病中发挥重要作用，包括与硬皮病相关的间质性肺纤维化。在这里，我们描述了暴露于凝血酶的正常肺成纤维细胞的信号通路，因为它们获得了肌成纤维细胞的两个主要特征：平滑肌(SM)α-肌动蛋白组织和胶原胶原凝胶收缩。我们的结果表明，小G蛋白Rho参与了肺肌成纤维细胞的分化。凝血酶以剂量依赖方式诱导Rho-S-35标记的鸟苷5‘-O-(3-硫代三磷酸)结合。它能在体内有效地刺激Rho活性，并启动蛋白激酶C(PKC)-epsilon-Rho复合体的形成。B毒素通过ADP核糖基化使Rho失活，抑制凝血酶诱导的SMα-肌动蛋白组织、胶原凝胶收缩、PKC-epsilon-SMα-肌动蛋白和PKC-epsilon-RhoA免疫共沉淀。然而，它对PKC-epsilon的激活或PKC-epsilon向膜的移位没有影响。过表达结构性活性的PKC-epsilon和结构性活性的RhoA可诱导胶原凝胶收缩或SMα-肌动蛋白组织，但它们各自并不执行这些功能。因此，我们得出结论，凝血酶诱导的肌成纤维细胞的收缩活动是通过依赖PKC-epsilon和RhoA的途径介导的，这两种分子都需要激活。我们推测，PKC-epsilon-RhoA复合体的形成是肺成纤维细胞凝血酶活化的早期事件，随后PKC-epsilon-SMα-肌动蛋白免疫共沉淀导致PKC-epsilon-RhoA-SMα-肌动蛋白三元复合体的形成。
Activated fibroblasts, or myofibroblasts, are crucial players in tissue remodeling, wound healing, and various fibrotic disorders, including interstitial lung fibrosis associated with scleroderma. Here we characterize the signaling pathways in normal lung fibroblasts exposed to thrombin as they acquire two of the main features of myofibroblasts: smooth muscle (SM) alpha-actin organization and collagen gel contraction. Our results show that the small G protein Rho is involved in lung myofibroblast differentiation. Thrombin induces Rho-S-35-labeled guanosine 5'-O-(3-thiotriphosphate) binding in a dose-dependent manner. It potently stimulates Rho activity in vivo and initiates protein kinase C (PKC)-epsilon-Rho complex formation. Toxin B, which inactivates Rho by ADP ribosylation, inhibits thrombin-induced SM alpha-actin organization, collagen gel contraction, and PKC-epsilon-SM alpha-actin and PKC-epsilon-RhoA coimmunoprecipitation. However, it has no effect on PKC-epsilon activation or translocation of PKC-epsilon to the membrane. Overexpression of constitutively active PKC-epsilon and constitutively active RhoA induces collagen gel contraction or SM alpha-actin organization, whereas, individually, they do not perform these functions. We therefore conclude that the contractile activity of myofibroblasts induced by thrombin is mediated via PKC-epsilon- and RhoA-dependent pathways and that activation of both of these molecules is required. We postulate that PKC-epsilon-RhoA complex formation is an early event in thrombin activation of lung fibroblasts, followed by PKC-epsilon-SM alpha-actin coimmunoprecipitation, which leads to the PKC-epsilon-RhoA-SM alpha-actin ternary complex formation.