Aim In diabetic patients, metformin appears to provide cardiovascular protection that cannot be attribu- ted only to its antihyperglycemic effects. Metformin is also known as the AMP-activated protein kinase （AMPK） ...Aim In diabetic patients, metformin appears to provide cardiovascular protection that cannot be attribu- ted only to its antihyperglycemic effects. Metformin is also known as the AMP-activated protein kinase （AMPK） ac- tivator. Our previous study suggested that metformin inhibits transforming growth factor-β1 （TGF-β1） production in a mouse heart failure model of pressure overload. TGF-β1 is a key factor in cardiac fibrosis and is usually induced by Angiotensin Ⅱ （Ang Ⅱ ） in the pressure overload mouse models. This study investigated the effect of metformin on cardiac fibrosis and TGF-β production induced by AngII and the underlying mechanisms. Methods C57/BL6 wild-type and AMPKα2 knockout mice were used. AngII （3 mg · kg-1 · d-1） was infused subcutaneously into mice for 7 days. Adult mouse cardiac fibroblasts were isolated and treated with AngII （ 1 μmol · L-1） and/or met- formin （1 mmol · L-l）. Results In C57/BL6 mice, metformin inhibits AngII-induced cardiac fibrosis. In cardi-ac fibroblasts, metformin inhibits TGF-β1 expression and production induced by AngII. AMPK inhibitor, com- pound C, reversed the effects of metformin. In vivo, AMPKα2 deficiency further increases AngII-induced TGF-β1 production. In cardiac fibroblasts, metformin inhibited AngII induced hepatocyte nuclear factor4 （HNF4ot protein level increase and HNF4α binding with TGF-β1 promoter using chromatin immunoprecipitation assay. In vivo, AMPKα2 deficiency further increased AngII-induced HNF4α protein level. Using HNF4α adenovirus, overexpress- ing HNF4α led to a 1.5-fold increase in TGF-β1 mRNA expression. HNF4a siRNA blocked AngII induced TGF- β1 production. Luciferase reporter with deleted HNF4a binding sites showed decreased TGFbl transcriptional activ- ity induced by AngII. In AMPK or2-/- heart, the inhibition of metformin on HNF4a protein was attenuated. Con- clusion Metformin inhibits AngII induced cardiac fibrosis and TGF-β1 production through AMPK activation. The underlying mechanism is that AMPK activation inhibits AngII induced HNF4α and then decreases TGF-β1 expres- sion.展开更多
目的研究长春市35~79岁汉族人群维生素D受体基因BsmⅠ、FokⅠ位点多态性的分布特征及其与腰椎骨密度(bone mineral density,BMD)的相关性,分析不同基因型对骨代谢的调节与影响,同时研究血清TGF-β、TRACP水平与腰椎BMD的相关性,为骨质...目的研究长春市35~79岁汉族人群维生素D受体基因BsmⅠ、FokⅠ位点多态性的分布特征及其与腰椎骨密度(bone mineral density,BMD)的相关性,分析不同基因型对骨代谢的调节与影响,同时研究血清TGF-β、TRACP水平与腰椎BMD的相关性,为骨质疏松预防、早期诊断和治疗提供分子生物学依据。方法应用Hologic Discovery WA型骨密度仪检测腰椎正位(L1-L4)BMD;采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)分析BsmⅠ和FokⅠ位点多态性;采用酶联免疫吸附分析法检测血清TGF-β、TRACP水平;采用SPSS 23.0软件进行统计分析。结果在500名汉族人群中,BsmⅠ位点基因型以bb型为主,占80.2%,Bb型占15.2%,BB型占4.6%;FokⅠ位点ff基因型占18.6%,Ff型占45.8%,FF型占35.6%。BsmⅠ位点各基因型骨质疏松组与非骨质疏松组分布特征组间差异无统计学意义(P>0.05);FokⅠ位点ff基因型骨质疏松组所占比例高于非骨质疏松组,差异有统计学意义(P<0.05)。BsmⅠ位点bb基因型男性、女性BMD值均低于Bb型和BB型,但差异无统计学意义(P>0.05);FokⅠ位点ff基因型男性、女性BMD值均低于Ff型和FF型,差异有统计学意义(P<0.05)。血清TGF-β水平骨质疏松组显著低于非骨质疏松组,而TRACP水平骨质疏松组高于非骨质疏松组,组间差异有统计学意义(P<0.05)。结论本研究500名汉族人群中,BsmⅠ位点以bb基因型为主,占80.2%,各基因型骨密度值组间差异无统计学意义;FokⅠ位点ff型BMD值低于Ff型和FF型,骨质疏松组ff基因型所占比例高于非骨质疏松组,差异有统计学意义,提示ff基因型可能是骨质疏松发生的危险因素;骨质疏松组血清TGF-β水平显著低于非骨质疏松组,而TRACP水平高于非骨质疏松组,差异有统计学意义,表明TGF-β、TRACP是评价骨代谢状态的良好指标。展开更多
文摘Aim In diabetic patients, metformin appears to provide cardiovascular protection that cannot be attribu- ted only to its antihyperglycemic effects. Metformin is also known as the AMP-activated protein kinase （AMPK） ac- tivator. Our previous study suggested that metformin inhibits transforming growth factor-β1 （TGF-β1） production in a mouse heart failure model of pressure overload. TGF-β1 is a key factor in cardiac fibrosis and is usually induced by Angiotensin Ⅱ （Ang Ⅱ ） in the pressure overload mouse models. This study investigated the effect of metformin on cardiac fibrosis and TGF-β production induced by AngII and the underlying mechanisms. Methods C57/BL6 wild-type and AMPKα2 knockout mice were used. AngII （3 mg · kg-1 · d-1） was infused subcutaneously into mice for 7 days. Adult mouse cardiac fibroblasts were isolated and treated with AngII （ 1 μmol · L-1） and/or met- formin （1 mmol · L-l）. Results In C57/BL6 mice, metformin inhibits AngII-induced cardiac fibrosis. In cardi-ac fibroblasts, metformin inhibits TGF-β1 expression and production induced by AngII. AMPK inhibitor, com- pound C, reversed the effects of metformin. In vivo, AMPKα2 deficiency further increases AngII-induced TGF-β1 production. In cardiac fibroblasts, metformin inhibited AngII induced hepatocyte nuclear factor4 （HNF4ot protein level increase and HNF4α binding with TGF-β1 promoter using chromatin immunoprecipitation assay. In vivo, AMPKα2 deficiency further increased AngII-induced HNF4α protein level. Using HNF4α adenovirus, overexpress- ing HNF4α led to a 1.5-fold increase in TGF-β1 mRNA expression. HNF4a siRNA blocked AngII induced TGF- β1 production. Luciferase reporter with deleted HNF4a binding sites showed decreased TGFbl transcriptional activ- ity induced by AngII. In AMPK or2-/- heart, the inhibition of metformin on HNF4a protein was attenuated. Con- clusion Metformin inhibits AngII induced cardiac fibrosis and TGF-β1 production through AMPK activation. The underlying mechanism is that AMPK activation inhibits AngII induced HNF4α and then decreases TGF-β1 expres- sion.
