Department of Physical Medicine and Rehabilitation, Kaohsiung Veterans General Hospital, Tainan, Taiwan, ROC; Department of Nursing, Chung-Hwa University of Medical Technology, Tainan, Taiwan, ROC.
Department of Surgery, Kaohsiung Veterans General Hospital, Tainan, Taiwan, ROC.
Exp Cell Res. 2018 Sep 1;370(1):160-167. doi: 10.1016/j.yexcr.2018.06.016. Epub 2018 Jun 18.
Peroxisome proliferator-activated receptor coactivator-1 alpha (PGC-1α) is a transcriptional coactivator that regulates energy metabolism and mitochondrial biogenesis. Recently, mitochondrial dysfunction has been indicated as an established risk factor for the development of renal fibrosis. However, whether PGC-1α is involved in the pathogenesis of renal fibrosis is unknown. In this study, we treated NRK-49F (normal rat kidney fibroblast) cells with transforming growth factor-beta 1 (TGF-β1) for 24 h to establish an in vitro fibrosis model. TGF-β1 induced the upregulation of type I collagen, fibronectin, TGF-β receptor I (TGFβ-RI), TGFβ-RII, Smad4, and pSmad2/3, as well as PGC-1α. NRK-49F cells transfected with pcDNA-PGC-1α showed significantly increased expression of fibronectin and type I collagen, as revealed by western blot assay. Interestingly, transfection with PGC-1α-siRNA caused a stark reversal of TGF-β1-induced cellular fibrosis, with concomitant suppression of fibronectin and type I collagen, as revealed by western blot and immunofluorescence assays. Moreover, SB431542 (TGFβ-RI), LY294002 (PI3K/Akt), and SB203580 (p38 MAPK), inhibitors of TGF-β-associated pathways, markedly suppressed TGF-β1-induced PGC-1α upregulation. These results implicate a role of PGC-1α in renal interstitial fibrosis mediated via the TGFβ-RI, PI3K/Akt, and p38 MAPK pathways. Our findings that PGC-1α-siRNA downregulates fibronectin and type I collagen suggest that it can be used as a novel molecular treatment for renal fibrosis.
过氧化物酶体增殖物激活受体共激活因子-1α（PGC-1α）是一种转录共激活因子，可调节能量代谢和线粒体生物发生。最近，线粒体功能障碍已被确定为肾纤维化发展的既定危险因素。然而，PGC-1α 是否参与肾纤维化的发病机制尚不清楚。在这项研究中，我们用转化生长因子-β1（TGF-β1）处理 NRK-49F（正常大鼠肾成纤维细胞）细胞 24 小时，建立体外纤维化模型。TGF-β1 诱导 I 型胶原、纤维连接蛋白、TGF-β 受体 I（TGFβ-RI）、TGFβ-RII、Smad4 和 pSmad2/3 以及 PGC-1α 的上调。pcDNA-PGC-1α 转染的 NRK-49F 细胞通过 Western blot 分析显示纤维连接蛋白和 I 型胶原的表达明显增加。有趣的是，PGC-1α-siRNA 的转染导致 TGF-β1 诱导的细胞纤维化明显逆转，同时伴随纤维连接蛋白和 I 型胶原的抑制，Western blot 和免疫荧光分析显示。此外，TGF-β 相关途径的抑制剂 SB431542（TGFβ-RI）、LY294002（PI3K/Akt）和 SB203580（p38 MAPK）显著抑制 TGF-β1 诱导的 PGC-1α 上调。这些结果表明 PGC-1α 通过 TGFβ-RI、PI3K/Akt 和 p38 MAPK 途径在肾间质纤维化中发挥作用。我们的研究结果表明，PGC-1α-siRNA 下调纤维连接蛋白和 I 型胶原，表明它可用作肾纤维化的新型分子治疗方法。
