Transforming Growth Factor-β Upregulates the Expression of Integrin and Related Proteins in MRC-5 Human Myofibroblasts
Transforming Growth Factor-β Upregulates the Expression of Integrin and Related Proteins in MRC-5 Human Myofibroblasts
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DOI：
10.1620/tjem.220.319
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发表时间：
2010-04-01
影响因子：
2.2
通讯作者：
Munakata, Hiroshi
中科院分区：
文献类型：
--
作者：
Honda, Eiko;Yoshida, Koji;Munakata, Hiroshi
肌成纤维细胞被定义为表达某些平滑肌分化特征的成纤维细胞。肌成纤维细胞的激活在纤维化中起着核心作用。转化生长因子-β是肌成纤维细胞的一种强有力的激活剂，即转化生长因子-β可引起肌成纤维细胞表型的改变，包括形态改变和作为肌成纤维细胞标志的α-平滑肌肌动蛋白(α-SMA)的表达。由于众所周知，体液因素，特别是转化生长因子-β和细胞外基质成分引起肌成纤维细胞的激活，我们检测了在转化生长因子-β激活MRC-5人肌成纤维细胞过程中整合素及其相关蛋白的表达。Western印迹分析显示，转化生长因子-β处理3d后，α-SMA的表达增加，免疫细胞化学显示α-SMA也是肌动蛋白应激纤维。免疫共沉淀实验显示，整合素α1、β3与整合素α1、整合素β3共沉淀，整合素β1与整合素β1、整合素β5共沉淀，整合素β1与整合素β1、整合素β5共沉淀。此外，实时定量聚合酶链式反应分析显示，转化生长因子-β促进I型胶原基因的表达，但不影响III型胶原基因的表达。这些结果表明，转化生长因子-β诱导MRC-5细胞纤维连接蛋白表达，进而诱导整合素受体αvβ3、αvβ1和α11β1的表达。该报告还表明，在转化生长因子-β介导的肌成纤维细胞激活过程中，整合素α11的表达上调。
Myofibroblasts are defined as fibroblasts that express certain features of smooth muscle differentiation. Activation of myofibroblasts plays a central role in fibrosis. Transforming growth factor-beta (TGF-beta) is a potent activator of myofibroblasts; namely, TGF-beta causes changes in myofibroblast phenotypes including morphological alterations and the expression of alpha-smooth muscle actin (alpha-SMA), a marker of myofibroblasts. Because it has been well known that humoral factors, especially, TGF-beta, and extracellular matrix components cause myofibroblast activation, we examined the expression of integrin and related proteins during activation of MRC-5 human myofibroblasts with TGF-beta. Western blot analysis revealed that TGF-beta treatment for 3 days increased the expression of alpha-SMA, which was also immunocytochemically observed as actin stress fibers. In the early phase of TGF-beta treatment, fibronectin expression was greatly increased, followed by the increased expression of integrin alpha v and alpha 11 and integrin beta 1 and beta 3. Co-immunoprecipitation assays revealed that the integrin av subunit was co-precipitated with integrin beta 1 and beta 3, and that integrin beta 1 was co-precipitated with all, alpha v, alpha 2, and alpha 5. The expression of focal adhesion kinase and integrin-linked kinase proteins was also upregulated by treatment with TGF-beta. In addition, the expression of type I collagen mRNA was increased by TGF-beta, but not type III collagen mRNA, as judged by real-time PCR analysis. These results suggest the possibility that TGF-beta induces fibronectin expression in MRC-5 cells, which subsequently induces the expression of integrin receptors, alpha v beta 3, alpha v beta 1, and alpha 11 beta 1. This report also shows that expression of integrin alpha 11 is upregulated during the TGF-beta-mediated activation of myofibroblasts.