Spectrin βⅡ通过改善线粒体功能减轻压力超负荷诱导的心力衰竭OA

Objective To investigate the expression changes,function and potential molecular mechanism of Spectrin βⅡ in pressure overload-induced heart failure.Methods A mouse model of pressure overload-induced heart failure was established by transverse aortic constriction(TAC),and the protein and mRNA expression levels of Spectrin βⅡ in myocardial tissue were detected 6 weeks after TAC surgery by Western blot and RT-qPCR,respectively.A cardiomyocyte hypertrophy model was induced by phenylephrine(PE)in neonatal mouse primary cardiomyocytes,and the protein and mRNA expression levels of Spectrin βⅡ in cardiomyocytes were also examined at 48 h after PE stimulation.C57BL/6J mice were randomly divided into four groups:sham operation+empty vector adenovirus group(sham+Ad-control),sham operation+Spectrin β Ⅱ overexpression group(sham+Ad-β Ⅱ SP),TAC+empty vector adenovirus group(TAC+Ad-control)and TAC+Spectrin βⅡ overexpression group(TAC+Ad-βⅡSP).Adenovirus was injected into myocardium at 7 d before modeling,and then TAC model was constructed.At 6 week after TAC,cardiac systolic function was evaluated by echocar-diography,cardiac structural changes were evaluated by wheat germ agglutinin(WGA)staining and Masson staining,and the mRNA expressions of myocardial hypertrophy markers[atrial natriuretic peptide(ANP),B-type natriuretic peptide(BNP)],and myocardial fibrosis markers[type Ⅰ collagen(COL Ⅰ),type Ⅲ collagen(COL Ⅲ)]were detected by RT-qPCR.Cardiomyocytes were divided into four groups:PBS+Ad-control group,PBS+Ad-βⅡSP group,PE+Ad-control group and PE+Ad-βⅡSP group.Cell viability was detected by CCK-8 assay,intracellular ATP content was detected by a ATP detection kit,mitochondrial membrane potential and mito-chondrial reactive oxygen species(ROS)levels were evaluated by JC-1 staining and MitoSOX staining,and the protein expressions of mitochondrial dynamics-related proteins[optic atrophy 1(OPA1),mitofusin 1(Mfn1),Mfn2 and dynamin-related protein 1(DRP1)]were detected by Western blot.Results Both protein and mRNA expression levels of Spectrin β Ⅱ were significantly decreased in myocardial tissues after TAC and PE-induced hypertrophic cardiomyocytes(all P<0.01).Compared with sham+Ad-control group,the mice in TAC+Ad-control group exhibited impaired cardiac systolic function,aggravated pathological myocardial hypertrophy and fibrosis,and elevated mRNA levels of hypertrophy and fibrosis markers(all P<0.01);while there were no significant differences in the above indexes between sham+Ad-control group and sham+Ad-βⅡSP group.Compared with TAC+Ad-control group,the cardiac systolic function was significantly improved in TAC+Ad-βⅡSP group,pathological hypertrophy and fibrosis were attenuated,and mRNA levels of hypertrophic and fibrotic markers decreased(all P<0.01).Compared with PBS+Ad-control group,cardiomyocyte viability,ATP content and mitochondrial membrane potential were decreased,mitochondrial ROS content was increased,the protein expressions of OPA1,Mfn1 and Mfn2 were decreased,and DRP1 expression was increased in PE+Ad-control group(all P<0.01);there were no significant differences in the above indexes between PBS+Ad-control group and PBS+Ad-βⅡSP group.Compared with PE+Ad-control group,car-diomyocyte viability,ATP content and mitochondrial membrane potential were improved,mitochondrial ROS content was decreased,the protein expressions of OPA1,Mfn1 and Mfn2 were increased,and DRP1 expression was decreased in PE+Ad-βⅡSP group(all P<0.01).Conclusion Cardiac pressure overload can significantly down-regulate myocardial Spectrin βⅡ expression.Overexpression of Spectrin βⅡ can attenuate pressure overload-induced pathological cardiac remodeling and improve cardiac systolic function by improving mitochondrial dynamics balance,reducing oxidative stress and enhancing energy metabolism,thereby delaying the progression of heart failure.