Epigallocatechin-3-gallate suppresses transforming growth factor-beta signaling by interacting with the transforming growth factor-beta typeⅡreceptor

• 作者: Ah-Mee Park Eiko Honda Hideaki Higashino Hiroshi Munakata Kana Ooshima Koji Yoshida Mamoru Isemura Masaki Tabuchi Sumio Hayakawa Tatsuki Itoh
• 来源期刊: 世界实验医学杂志
• 学科: 医学
• 关键词: Epigallocatechin-3-gallate TRANSFORMING growth factor-β MYOFIBROBLAST α-smooth muscle ACTIN Fibrosis
• 年，卷（期）: 2013,（4）
• 页码范围: 100-107
• 页数: 8页
• 分类号: R392

摘要

AIM:To investigate the(-)-epigallocatechin-3-gallate(EGCG)binding to transforming growth factor-β(TGF-β)typeⅡreceptor(TGFRⅡ).METHODS:The expression ofα-smooth muscle actin(α-SMA)was used as a marker for fibrotic change in human lung fibroblast MRC-5 cells.Theα-SMA expression level was determined by western blotting and immunohistological analysis.We examined whether the anti-fibrotic effects of EGCG on MRC-5 cells was dependent on antioxidant mechanism by using edaravone and N-acetylcysteine(NAC).The suppression effects of EGCG on Smad2/3 activation were studied by confocal fluorescence microscopy.The binding of EGCG to recombinant TGFRⅡprotein was analyzed by immunoprecipitation and affinity chromatography.RESULTS:When MRC-5 cells were treated with TGF-β,EGCG decreased the expression ofα-SMA in a dose dependent manner,whereas catechin did not influence theα-SMA expression in the cells.Except for EGCG,antioxidant compounds(e.g.,edaravone and NAC)had no effects on the TGF-β-inducedα-SMA expression.Nuclear localization of phosphorylated Smad2/3 was observed after TGF-βtreatment;however,EGCG treatment attenuated the nuclear transportation of Smad2/3 in the presence or absence of TGF-β.After a TGFRⅡexpression vector was introduced into COS-7 cells,cell lysates were untreated or treated with EGCG or catechin.The immunoprecipitation experiments using the lysates showed that EGCG dose-dependently bound to TGFRⅡand that catechin did not at all.Affinity chromatography study indicated that EGCG would bind to TGFRⅡ.CONCLUSION:Our results demonstrate that EGCG interacts with TGFRⅡand inhibits the expression ofα-SMA via the TGF-β-Smad2/3 pathway in human lung fibroblast MRC-5 cells.