Elucidation of the mechanism that BMP-2 suppresses TGF-β1-induced renal cellular fibrosis

[[abstract]]上皮-間質轉換EMT ( epithelial -mesenchymal transition ) 在胚胎發育上是一個不可或缺的過程。但是在某些晚期的慢性腎疾病中，腎臟纖維化的間質纖維母細胞確是源自於一群腎小管的上皮細胞經歷了一個EMT的過程而來。目前已經知道第一型乙型轉型生長因子TGF-β1 ( transforming growth factor-beta1 ) 能夠在腎臟纖維化的過程中誘導細胞纖維化並且促進EMT的發生。儘管如此，上皮細胞可塑性的能力也同時受到TGF-β1的相關蛋白第二型骨髓生長因子BMP-2 ( bone morphogenetic protein-2 ) 所調節。我們先前的研究發現正常大鼠腎間質纖維母細胞 ( NRK-49F ) 短暫刺激BMP-2 ( 24hr ) 能對抗TGF-β1誘發腎臟細胞纖維化的現象。在這份研究中，我們將探討在正常大鼠腎間質纖維母細胞中BMP-2、TGF-β1和EMT的相互調控機制。培養NRK-49F於TGF-β1 ( 10 ng/mL ) 會誘導EMT的進行，使得α-SMA、 Fibronectin和Snail蛋白表現增加以及E-cadherin蛋白的降低而逐漸失去上皮細胞的型態。若共同刺激TGF-β1 ( 10 ng/mL ) 和BMP-2 ( 10、50、250 ng/mL ) 的劑量24小時則可以逆轉TGF-β1誘導EMT的進行，並且再度重新表現E-cadherin蛋白並且降低α-SMA、Fibronectin和Snail蛋白。這些數據表示BMP-2抑制TGF-β1誘導正常大鼠腎間質纖維母細胞的纖維化會經由調節Snail表現以及EMT的過程。 EMT ( epithelial- mesenchymal transition ) is an integral process during development. But some later phase of chronic kidney disease, the interstitial fibroblasts actually originate from tubular epithelial cells via the EMT in renal fibrogenesis. Transforming growth factor beta ( TGF-β1 ) has been known as the main cytokine involved in the pathogenesis of renal fibrogenesis and also capable of initiating and completing the entire EMT course. Although, epithelial plasticity can also be regulated by a member of the TGF-β1 superfamily bone morphogenetic protein-2 ( BMP-2 ). Our previous study showed that short-term treatment ( 24 hr ) of BMP-2 in NRK-49F ( rat fibroblast ) cells could antagonize TGF-β1 -induced fibrogenesis. In this study, We investigate the interactions of BMP-2, TGF-β1 and EMT process in NRK-49F. Cultured NRK-49F cells were treated with TGF-β1 ( 10 ng/mL ) for 24 hours could be induced EMT, in association with increased α-SMA, Fibronectin, Snail expression, decreased E-cadherin expression and loss of epithelial morphology. A combination of TGF-β1 ( 10 ng/mL ) in BMP-2 dose-dependent manner ( 10, 50, 250 ng/mL ) for 24 hours could be reversed TGF-β1-induced EMT, in association with reexpression of endogenous E-cadherin and degrade α-SMA, Fibronectin and Snail. These data suggest that BMP-2 attenuates TGF-β1-induced renal cell fibrosis could be through mediated Snail and EMT process