The differential role of Smad2 and Smad3 in the regulation of pro-fibrotic TGFβ1 responses in human proximal-tubule epithelial cells
The differential role of Smad2 and Smad3 in the regulation of pro-fibrotic TGFβ1 responses in human proximal-tubule epithelial cells
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DOI：
10.1042/bj20051106
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发表时间：
2006-01-15
影响因子：
4.1
通讯作者：
Dockrell, MEC
中科院分区：
文献类型：
--
作者：
Phanish, MK;Wahab, NA;Dockrell, MEC
在慢性肾脏疾病中，肾功能的进行性丧失与肾小管间质纤维化的进展相关。TGF β 1-Smad（转化生长因子-β 1-Sma和Mad蛋白）信号传导在肾小管间质纤维化的发展中起重要作用。由PTEC（近端小管上皮细胞）分泌CTGF（结缔组织生长因子; CCN 2）和响应于TGF β的PTEC向肌成纤维细胞的EMT（上皮-间充质转分化）是肾小管间质纤维化发展中的关键Smad依赖性事件。在本研究中，我们已经调查了不同的贡献，Smad 2和Smad 3表达的CTGF，E-钙粘蛋白，α-SMA（α-平滑肌肌动蛋白）和MMP-2（基质金属蛋白酶-2）在体外培养模型的HKC-8（转化的人PTECs）的TGF β 1治疗。RNA干扰用于实现Smad 2和Smad 3的选择性和特异性敲低。通过Western免疫印迹法评估细胞E-钙粘蛋白、α-SMA以及分泌的CTGF和MMP-2。TGF β 1治疗诱导了CTGF、MMP-2和α-SMA表达增加和E-钙粘蛋白表达减少的纤维化表型。TGF β 1诱导的CTGF增加和E-cadherin表达减少是Smad 3依赖性的，而MMP-2表达增加是Smad 2依赖性的。α-SMA表达的增加依赖于Smad 2和Smad 3，并通过Smad 2和Smad 3的联合敲低而消除。总之，我们已经证明了Smad 2和Smad 3在TGF β 1诱导的CTGF表达和人PTECs中EMT标志物中的不同作用。这在设计针对肾小管间质纤维化的靶向抗纤维化疗法中可能具有治疗价值。
In chronic renal diseases, progressive loss of renal function correlates with advancing tubulo-interstitial fibrosis. TGF beta 1-Smad (transforming growth factor-beta 1-Sma and Mad protein) signalling plays an important role in the development of renal tubulo-interstitial fibrosis. Secretion of CTGF (connective-tissue growth factor; CCN2) by PTECs (proximal-tubule epithelial cells) and EMT (epithelial-mesenchymal transdifferentiation) of PTECs to myofibroblasts in response to TGF beta are critical Smad-dependent events in the development of tubulo-interstitial fibrosis. In the present study we have investigated the distinct contributions of Smad2 and Smad3 to expression of CTGF, E-cadherin, alpha-SMA (alpha-smooth-muscle actin) and MMP-2 (matrix-metalloproteinase-2) in response to TGF beta 1 treatment in an in vitro culture model of HKC-8 (transformed human PTECs). RNA interference was used to achieve selective and specific knockdown of Smad2 and Smad3. Cellular E-cadherin, a-SMA as well as secreted CTGF and MMP-2 were assessed by Western immunoblotting. TGF beta 1 treatment induced a fibrotic phenotype with increased expression of CTGF, MMP-2 and alpha-SMA, and decreased expression of E-cadherin. TGF beta 1-induced increases in CTGF and decreases in E-cadherin expression were Smad3-dependent, whereas increases in MMP-2 expression were Smad2-dependent. Increases in alpha-SMA expression were dependent on both Smad2 and Smad3 and were abolished by combined knockdown of both Smad2 and Smad3. In conclusion, we have demonstrated distinct roles for Smad2 and Smad3 in TGF beta 1-induced CTGF expression and markers of EMT in human PTECs. This can be of therapeutic value in designing targeted anti-fibrotic therapies for tubulointerstitial fibrosis.