二甲雙胍通過靶向肝細胞核因子-4-α降低血管緊張素ii誘導(dǎo)的tgf - β1表達

2017年3月，京大學(xué)第三醫(yī)院血管醫(yī)學(xué)研究所(Institute of Vascular Medicine, Peking University Third Hospital, No. 49, Huayuan Bei Road, Haidian District, Beijing, 100191, China.) Ruifei Chen老師研究團隊在《British Journal of Pharmacology》上發(fā)表論文：

“Metformin attenuates angiotensin II-induced TGFβ1 expression by targeting hepatocyte nuclear factor-4-α”

“二甲雙胍通過靶向肝細胞核因子-4-α降低血管緊張素ii誘導(dǎo)的tgf - β1表達”

Abstract：

Background and purpose: Metformin, a small molecule, antihyperglycaemic agent, is a well-known activator of AMP-activated protein kinase (AMPK) and protects against cardiac fibrosis. However, the underlying mechanisms remain elusive. TGFβ1 is a key cytokine mediating cardiac fibrosis. Here, we investigated the effects of metformin on TGFβ1 production induced by angiotensin II (AngII) and the underlying mechanisms.

Experimental approach: Wild-type and AMPKα2-/- C57BL/6 mice were injected s.c. with metformin or saline and infused with AngII (3 mg·kg-1 ·day-1 ) for 7 days. Adult mouse cardiac fibroblasts (CFs) were isolated for in vitro experiments.

Key results: In CFs, metformin inhibited AngII-induced TGFβ1 expression via AMPK activation. Analysis using bioinformatics predicted a potential hepatocyte nuclear factor 4α (HNF4α)-binding site in the promoter region of the Tgfb1 gene. Overexpressing HNF4α increased TGFβ1 expression in CFs. HNF4α siRNA attenuated AngII-induced TGFβ1 production and cardiac fibrosis in vitro and in vivo. Metformin inhibited the AngII-induced increases in HNF4α protein expression and binding to the Tgfb1 promoter in CFs. In vivo, metformin blocked the AngII-induced increase in cardiac HNF4α protein levels in wild-type mice but not in AMPKα2-/- mice. Consequently, metformin inhibited AngII-induced TGFβ1 production and cardiac fibrosis in wild-type mice but not in AMPKα2-/- mice.

Conclusions and implications: HNF4α mediates AngII-induced TGFβ1 transcription and cardiac fibrosis. Metformin inhibits AngII-induced HNF4α expression via AMPK activation, thus decreasing TGFβ1 transcription and cardiac fibrosis. These findings reveal a novel antifibrotic mechanism of action of metformin and identify HNF4α as a new potential therapeutic target for cardiac fibrosis.

摘要：

背景和目的:二甲雙胍是一種小分子的抗高血糖藥物，是一種眾所周知的amp活化蛋白激酶(AMPK)的激活劑，可以防止心臟纖維化。然而，潛在的機制仍然難以捉摸。tgf - β1是介導(dǎo)心臟纖維化的關(guān)鍵細胞因子。在這里，我們研究了二甲雙胍對血管緊張素II (AngII)誘導(dǎo)的tgf - β1產(chǎn)生的影響及其潛在機制。

實驗方法:野生型和AMPKα2-/- C57BL/6小鼠腹腔注射二甲雙胍或生理鹽水，同時注射AngII (3 mg·kg-1·day-1)，持續(xù)7 d。分離成年小鼠心臟成纖維細胞(CFs)進行體外實驗。

關(guān)鍵結(jié)果:在CFs中，二甲雙胍通過激活A(yù)MPK抑制血管內(nèi)皮細胞誘導(dǎo)的tgf - β1表達。生物信息學(xué)分析預(yù)測了Tgfb1基因啟動子區(qū)域潛在的肝細胞核因子4α (HNF4α)結(jié)合位點。過表達HNF4α可增加CFs中tgf - β1的表達。在體外和體內(nèi)，HNF4α siRNA可減弱血管誘導(dǎo)的tgf - β1生成和心臟纖維化。二甲雙胍抑制血管內(nèi)皮素誘導(dǎo)的CFs中HNF4α蛋白表達和與Tgfb1啟動子結(jié)合的增加。在體內(nèi)，二甲雙胍阻斷了野生型小鼠血管i誘導(dǎo)的心臟HNF4α蛋白水平的升高，但在AMPKα2-/-小鼠中沒有。因此，二甲雙胍在野生型小鼠中抑制血管內(nèi)皮素誘導(dǎo)的tgf - β1的產(chǎn)生和心臟纖維化，而在AMPKα2-/-小鼠中沒有作用。

結(jié)論和意義:HNF4α介導(dǎo)血管誘導(dǎo)的tgf - β1轉(zhuǎn)錄和心臟纖維化。二甲雙胍通過激活A(yù)MPK抑制血管內(nèi)皮素誘導(dǎo)的HNF4α表達，從而降低TGFβ1轉(zhuǎn)錄和心臟纖維化。這些發(fā)現(xiàn)揭示了二甲雙胍的一種新的抗纖維化作用機制，并確定了HNF4α作為心臟纖維化的一個新的潛在治療靶點。

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