Stimulation of pro-α1(I) collagen by TGF-β1 in mesangial cells:: role of the p38 MAPK pathway
Stimulation of pro-α1(I) collagen by TGF-β1 in mesangial cells:: role of the p38 MAPK pathway
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DOI：
10.1152/ajprenal.2001.280.3.f495
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发表时间：
2001-03-01
影响因子：
4.2
通讯作者：
Choi, ME
中科院分区：
文献类型：
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作者：
Chin, BY;Mohsenin, A;Choi, ME
转化生长因子-β(1)是细胞外基质蛋白合成的有效诱导剂，也是肾纤维化的关键介质。然而，转化生长因子-β(1)刺激这一过程的细胞内信号机制仍不完全清楚。在这篇报道中，我们研究了属于丝裂原活化蛋白激酶(MAPK)超家族的一个主要的应激激活的细胞内信号级联在介导大鼠肾小球系膜细胞的转化生长因子-β(1)反应中的作用，采用显性-负性抑制转化生长因子-β(1)信号受体。我们首先用一种激酶缺失的突变型转化生长因子-βII型受体(T-Betar-IIM)稳定地转染大鼠肾小球系膜细胞，该受体旨在以显性-负向方式抑制转化生长因子-β(1)信号。Northern分析证实了T Betar-IIM基因的表达。I-125标记的转化生长因子-β(1)亲和交联法检测T-Betar-IIM蛋白在细胞表面的表达及其与配体的结合。转化生长因子-β(1)能迅速诱导野生型和空载体(PcDNA3)转染的对照组肾小球系膜细胞中p38MAPK的磷酸化。有趣的是，显性阴性T Betar-IIM未能阻断转化生长因子-β(1)诱导的p38MAPK的磷酸化。显性负性T Betar-IIM不能阻断转化生长因子-β(1)诱导的前-α(1)(I)型胶原基因表达和细胞蛋白合成，但可阻断转化生长因子-β(1)诱导的细胞外信号调节激酶(ERK)1/ERK2的激活和抗增殖反应。在p38MAPK特异性抑制剂SB-203580存在下，转化生长因子-β(1)不能刺激对照组和转染组肾小球系膜细胞α(1)(I)前胶原基因的表达。最后，我们证实了p38MAPK的激活和前α(1)(I)胶原的刺激都是转化生长因子-β(1)的作用，这种作用被转化生长因子-βI型受体的显性-负性抑制所消除。因此，我们首次展示了转化生长因子-β(1)在系膜细胞中激活p38MAPK，并且，考虑到快速的动力学，这种转化生长因子-β(1)的作用可能是直接的。此外，我们的研究结果表明，p38MAPK通路在转化生长因子-β(1)诱导的系膜细胞α-前胶原(1)(I)的信号转导中起作用。
Transforming growth factor-beta (1) (TGF-beta (1)) is a potent inducer of extracellular matrix protein synthesis and a key mediator of renal fibrosis. However, the intracellular signaling mechanisms by which TGF-beta (1) stimulates this process remain incompletely understood. In this report, we examined the role of a major stress-activated intracellular signaling cascade, belonging to the mitogen-activated protein kinase (MAPK) superfamily, in mediating TGF-beta (1) responses in rat glomerular mesangial cells, using dominant-negative inhibition of TGF-beta (1) signaling receptors. We first stably transfected rat glomerular mesangial cells with a kinase-deleted mutant TGF-beta type II receptor (T betaR-IIM) designed to inhibit TGF-beta (1) signaling in a dominant-negative fashion. Next, expression of T betaR-IIM mRNA was confirmed by Northern analysis. Cell surface expression and ligand binding of T betaR-IIM protein were demonstrated by affinity cross-linking with I-125-labeled-TGF-beta (1). TGF-beta (1) rapidly induced p38 MAPK phosphorylation in wild-type and empty vector (pcDNA3) transfected control mesangial cells. Interestingly, transfection with dominant-negative T betaR-IIM failed to block TGF-beta (1) induced p38 MAPK phosphorylation. Moreover, dominant-negative T betaR-IIM failed to block TGF-beta (1)-stimulated pro-alpha (1) (I) collagen mRNA expression and cellular protein synthesis, whereas TGF-beta (1)-induced extracellular signal-regulated kinase (ERK) 1/ERK2 activation and antiproliferative responses were blocked by T betaR-IIM. In the presence of a specific inhibitor of p38 MAPK, SB-203580, TGF-beta (1) was unable to stimulate pro-alpha (1) (I) collagen mRNA expression in the control and T betaR-IIM-transfected mesangial cells. Finally, we confirmed that both p38 MAPK activation and pro-alpha (1) (I) collagen stimulation were TGF-beta (1) effects that were abrogated by dominant-negative inhibition of TGF-beta type I receptor. Thus we show first demonstration of p38 MAPK activation by TGF-beta (1) in mesangial cells, and, given the rapid kinetics, this TGF-beta (1) effect is likely a direct one. Furthermore, our findings suggest that the p38 MAPK pathway functions as a component in the signaling of pro-alpha (1) (I) collagen induction by TGF-beta (1) in mesangial cells.