RGC-32 Mediates Transforming Growth Factor-β-induced Epithelial-Mesenchymal Transition in Human Renal Proximal Tubular Cells
RGC-32 Mediates Transforming Growth Factor-β-induced Epithelial-Mesenchymal Transition in Human Renal Proximal Tubular Cells
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DOI：
10.1074/jbc.m900039200
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发表时间：
2009-04-03
影响因子：
4.8
通讯作者：
Chen, Shi-You
中科院分区：
文献类型：
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作者：
Huang, Wen-Yan;Li, Zu-Guo;Chen, Shi-You
上皮-间质转化（EMT）发生在几种疾病状态中，包括肾纤维化和癌变。肾小管细胞EMT产生的肌成纤维细胞在肾间质纤维化的很大一部分中负责细胞外基质成分的沉积。转化生长因子- β (tgf - β)在肾小管细胞的EMT中起着重要作用，但控制这一过程的分子机制在很大程度上仍然未知。在这项研究中，我们发现RGC-32（对补体32的反应基因）对于tgf - β诱导的人肾近端小管细胞（hptc）的EMT至关重要。RGC-32在hptc中通常不表达。然而，tgf - β刺激在诱导EMT的同时显著激活RGC-32，如诱导平滑肌α -肌动蛋白（α - sma）和细胞外基质蛋白胶原I和纤维连接蛋白，以及上皮标志物E-cadherin的减少所示。tgf - β功能由多种信号通路介导，但HPTCs中的RGC-32表达似乎主要受Smad调控。功能上，RGC-32似乎介导tgf - β诱导的htcs EMT。短发夹干扰RNA阻断RGC-32可显著抑制tgf - β诱导的肌成纤维细胞标记基因α - sma，同时抑制E-cadherin的表达。相反，过表达RGC-32诱导α - sma表达，同时恢复E-cadherin。RGC-32还抑制另一种粘附连接蛋白n -钙粘蛋白的表达，表明RGC-32单独诱导肾上皮细胞向肌成纤维细胞的表型转化。进一步的研究表明，RGC-32刺激细胞外基质成分纤维连接蛋白和胶原蛋白i的产生。在机制上，RGC-32通过激活其他转录因子（如蜗牛和鼻涕虫）诱导EMT。在tgf - β诱导的EMT中，RGC-32敲低抑制Snail和Slug的表达。综上所述，我们的数据首次证明RGC-32在tgf - β诱导的肾小管细胞EMT中起关键作用。
Epithelial-mesenchymal transition (EMT) occurs in several disease states, including renal fibrosis and carcinogenesis. Myo-fibroblasts produced from EMT of renal tubular cells are responsible for the deposition of extracellular matrix components in a large portion of renal interstitial fibrosis. Transforming growth factor-beta (TGF-beta) plays an essential role in the EMT of renal tubular cells, but the molecular mechanism governing this process remains largely unknown. In this study, we found that RGC-32 ( response gene to complement 32) is critical for TGF-beta-induced EMT of human renal proximal tubular cells (HPTCs). RGC-32 is not normally expressed in the HPTCs. However, TGF-beta stimulation markedly activates RGC-32 while inducing an EMT, as shown by the induction of smooth muscle alpha-actin (alpha-SMA) and extracellular matrix proteins collagen I and fibronectin, as well as the reduction of epithelial marker E-cadherin. TGF-beta function is mediated by several signaling pathways, but RGC-32 expression in HPTCs appears to be mainly regulated by Smad. Functionally, RGC-32 appears to mediate TGF-beta-induced EMT of HPTCs. Blockage of RGC-32 using short hairpin interfering RNA significantly inhibits TGF-beta induction of myofibroblast marker gene alpha-SMA while repressing the expression of E-cadherin. In contrast, overexpression of RGC-32 induces alpha-SMA expression while restoring E-cadherin. RGC-32 also inhibits the expression of another adherens junction protein, N-cadherin, suggesting that RGC-32 alone induces the phenotypic conversion of renal epithelial cells to myofibroblasts. Additional studies show that RGC-32 stimulates the production of extracellular matrix components fibronectin and collagen I. Mechanistically, RGC-32 induces EMT via the activation of other transcription factors such as Snail and Slug. RGC-32 knockdown inhibits the expression of Snail and Slug during TGF-beta-induced EMT. Taken together, our data demonstrate for the first time that RGC-32 plays a critical role in TGF-beta-induced EMT of renal tubular cells.