| Background Myocardial hypertrophy is an independent risk factor of cardiovascular accident and mortality,which is a serious threat to human life and health.The current study suggests a variety of mechanical stress and neurohumoral factors such as angiotensin II(angiotensin II,Ang II),endothelin,transforming growth factor beta,etc al can induce myocardial hypertrophy.Bone morphogenetic protein 4(BMP4)is a member of the transforming growth factor-beta(TGF-β)superfamily,Research has shown BMP4 can induce pathological myocardial hypertrophy,but the underlying molecular mechanism is not clear.Autophagy is a kind of life in the widely exists in eukaryotic cells and is highly conserved in evolution process of the degradation process,in maintaining cell survival,differentiation,and steady state is of great significance.In recent years,much attention has been paid to the role of autophagy in myocardial hypertrophy,but the specific molecular mechanism is unclear.Extracellular signal regulating kinase(extracellular signal-regulated kinase1/2,ERK1/2)signaling pathway plays an important role in myocardial hypertrophy.So we speculated that BMP4 may by regulating cell autophagy activation ERK1/2 signaling pathways induced cardiomyocyte hypertrophy.Objectives To observe the effect of the BMP4 on the H9C2 Myocardial cells in rats,elucidate the role and mechanism of autophagy in Bone morphogenetic protein 4(BMP4)induced H9C2 myocyte hypertrophy in rats,It can also provide experimental foundation and theoretical basis for the clinical treatment for myocardial hypertrophy.Methods H9C2 rats cardiac muscle cell lines(H9C2)were cultured.Firstly,To establish myocyte hypertrophy Model induced by BMP4.Dividing the cells into CON,BMP4(50μg/L)and Ang II(1×10-7mol/L)randomly which were cultured 48 hours subsequently.Secondly,to observe the change of ERK1/2 protein phosphorylation expression after treating BMP4,With BMP4 50μg/L at different time(0 min,10 min,30min,60 min,120min)and at different does(0μg/L,10μg/L,50μg/L,100μg/L)for 30 min.Subsequently,H9C2 cardiomyocyte where divided into Con,BMP4,BMP4+PD98059 and BMP4+3MA randomly,With PD98059(50μmol/L)and 3MA(5mmol/L)blockaging for 30 min,We add BMP4(50μg/L).Tiny tubes related proteins 1 light chain 3(LC3)and p-ERK1/2 are detected after culturing 30 min,cell surface area,average protein content and α-smooth muscle actin(α-SMA)protein expression level.are observed after 48 h.Cell Size Was Measured by inverted microscope and image J Software.Total protein were detected by BCA,Western Blot was used to measure the expression of LC3,ERK1/2,p-ERK1/2 and brain natriuretic factor or peptide(BNP),α-SMA.Results 1.The cell area,protein content and the BNP protein expression level were significantly higher in BMP4 than in control group(P<0.01),but lower than in angiotensin II(Ang II)group(P<0.05).2.1)With BMP4(50μg/L)treated 30 min,ERK1/2 protein phosphorylation expression is higher than 10 min(P<0.05),especially higher than 0 min(control group),60 min and 120min(P<0.01),But there was no difference between 0 min(control group)and 120 min(P>0.05);2)After different concentrations of BMP4 intervention,100μg/L is higher than 50μg/L and significantly higher than 0μg/L(control group),10μg/L(P<0.01).After 30 min,The expression of LC3 and p-ERK1/2 were significantly higher in BMP4 than in control group[(1.54±0.05)vs(1.95±0.11),(0.94±0.04)vs(1.33±0.06),P < 0.01];They are significantly decrease in BMP4+PD98059 and BMP4+3MA than in BMP4[(1.95±0.11)vs(1.59±0.08)、(1.36±0.02),(1.33±0.06)vs(0.87±0.05)、(0.95±0.15),P<0.01];while similar with BMP4+PD98059 and BMP4+3MA.After 48 h,The cell area,protein content and the α-SMA protein expression level are significantly lower in control than in BMP4 group,[(644.1±15.01)μm2 vs(745.6±14.43)μm2,(240.0±7.26)pg/cell vs(347.1±5.4)pg/cell,(1.22±0.06 vs 1.99±0.03),P < 0.01],which are significantly higher than in BMP4+PD98059 and BMP4+3MA.[(745.6±14.43)μm2 vs(645.0±12.63)μm2 、(647.7±13.89)μm2,(347.1±5.4)pg/cell vs(239.7±3.39)pg/cell 、(241.1±8.56)pg/cell,(1.99±0.03)vs(1.13±0.05)、(1.12±0.02),P < 0.01].But there was no difference between BMP4+PD98059and BMP4+3MA(P>0.05).Conclusions 1.BMP4 may through the activation of ERK1/2 signaling pathways induced rat H9C2 myocyte hypertrophy;2.The activation of BMP4 induced myocardial hypertrophy cell autophagy 3.ERK1/2 May regulate the cell autophagy 4.Cell autophagy may by activating ERK1/2 signaling pathways mediating the BMP4 induction H9C2 myocyte hypertrophy in rats 5.Blocking cell autophagy or ERK1/2 the activation of signaling pathways,may have therapeutic effect on myocardial hypertrophy. |
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