Activation of STAT3/Smad1 is a key signaling pathway for progression to glomerulosclerosis in experimental glomerulonephritis
Activation of STAT3/Smad1 is a key signaling pathway for progression to glomerulosclerosis in experimental glomerulonephritis
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DOI：
10.1074/jbc.m411064200
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发表时间：
2005-02-25
影响因子：
4.8
通讯作者：
Doi, T
中科院分区：
文献类型：
--
作者：
Takahashi, T;Abe, H;Doi, T
系膜细胞增殖是进行性肾小球损伤发展过程中的重要事件。然而，细胞增殖如何参与肾小球硬化症的发展尚不清楚。最近，我们发现，过度表达的IV型胶原（Col IV），系膜细胞外基质的主要组成部分，在糖尿病肾小球硬化的Smad 1的转录调控。在这项研究中，我们已经证明了抗血小板源性生长因子（PDGF）β受体抗体（APB 5）的管理阻断激活的PDGF-B链对大鼠肾小球肾炎的影响，并检查了在体内和体外调节肾小球细胞增殖和肾小球硬化的信号通路。用抗大鼠Thy-1.1单克隆抗体诱发实验性系膜增生性肾小球肾炎（Thy 1GN）。在Thy 1 GN中，系膜细胞增殖和Col IV的表达在第6天达到峰值。免疫组织化学染色;对于Smad 1、磷酸化Smad 1（pSmad 1）和磷酸化STAT 3（pSTAT 3）的表达，显示肾小球Smad 1表达的峰值出现在第6天，与系膜增殖的峰值一致。pSmad 1在发病第1天表达上调，肾小球pSmad 1表达高峰出现在发病第4天。当用AP 135处理时，系膜增殖和硬化均显著减少。Smad 1、pSmad 1和pSTAT 3的表达也通过施用AP 135而显著降低。PDGF诱导系膜细胞复制和Col IV合成，并增加培养的系膜细胞上pSTAT 3和pSmad 1的表达。此外，APB 5降低肾小球系膜细胞增殖与体外pSmad 1，pSTAT 3和Col IV蛋白表达降低相关。显性负性STAT 3的引入显著降低了培养的系膜细胞中Col IV的表达。提示STAT 3和Smad 1的激活参与了实验性肾小球肾炎肾小球硬化的发生发展过程。
Mesangial cell proliferation is a significant event in the development of progressive glomerular injuries. However, the issue of how cell proliferation is involved in the development of glomerulosclerosis is unclear. Recently, we showed that the overexpression of type IV collagen (Col IV), a major component of mesangial extracellular matrix, is transcriptionally regulated by Smad1 in diabetic glomeruloselerosis. In this study, we have demonstrated the effect of the administration of an anti-platelet-derived growth factor (PDGF) beta-receptor antibody (APB5) blocking activation by the PDGF-B chain on rat glomerulonephritis and have examined the signaling pathways that regulate both glomerular cell proliferation and glomeruloselerosis in vivo and in vitro. Experimental mesangial proliferative glomerulonephritis (Thy1 GN) was induced by a single intravenous injection of anti-rat Thy-1.1 monoclonal antibody. In Thy1 GN, mesangial cell proliferation and the expression of Col IV peaked at day 6. Immunohistochemical staining ;for the expression of Smad1, phospho-Smad1 (pSmad1), and phospho-STAT3 (pSTAT3) revealed that the peak for glomerular Smad1 expression occurred at day 6, consistent with the peak for mesangial proliferation. The expression of pSmad1 was up-regulated at day 1, and the peak for glomerular pSmad1 expression occurred at day 4 of the disease. When treated with AP135, both mesangial proliferation and sclerosis were reduced significantly. The expression of Smad1, pSmad1, and pSTAT3 was also significantly reduced by the administration of AP135. PDGF induced both mesangial cell replication and Col IV synthesis in association with an increased expression of pSTAT3 and pSmad1 on cultured mesangial cells. In addition, APB5 reduced mesangial cell proliferation in association with decreased pSmad1, pSTAT3, and Col IV protein expressions in vitro. The introduction of dominant negative STAT3 significantly decreased the expression of Col IV in cultured mesangial cells. These data suggest that the activation of STAT3 and Smad1 participates in the developing process of glomerulosclerosis in experimental glomerulonephritis.