Down-regulation Of Mitofusin2 Contributes To Doxorubicin-induced Cardiomyocytes Apoptosis

BackgroundDoxorubicin(DOX)is an anti-tumor agent that is widely used in clinic for treatment of cancers.The clinical application of the medication,however,is limited by its cardiac toxicity which can induce cardiomyocyte injury and cause heart failure through an undefined mechanism.Mitofusin 2(Mfn2)is a mitochondrial GTPase fusion protein that is located on the outer membrane of mitochondria(OMM).The mfn2 plays an important role in mitochondrial fusion.ObjectiveThe aim of this study is to identify the role of the Mfn2 in DOX-induced cardiomyocyte apoptosis.MethodsIn this study,cultured primary cardiomyocytes were obtained from Sprague Dawley(SD)rats born within 1 to 3 days.The experimental group was divided into three groups:DOX group and Mfn2 transfection group and Mitotempo pretreatment group.The normal cardiomyocytes were used as the control group and the control group was not treated.Mfn2 transfection group was transferred into Mfn2 activation plasmid in myocardium and then treated with DOX.The Mitotempo pretreatment group was pretreated with Mitotempo for 1 hour and then treated with DOX.The expression of Mfn2 in myocardium was detected by Western Blotting(WB).The reactive oxygen species(ROS)in myocardium and mitochondria were detected by DCFDA and mitochondrial specific fluorescent dye MitoSOX,respectively.The apoptosis of cardiomyocytes was detected by detecting the activity of Caspase 3 and TUNEL staining in cardiomyocytes.Results1.Challenging of the cardiomyocytes with DOX resulted in increased CM oxidant production and CM apoptosis.2.In addition,condition of the cardiomyocytes with DOX deceased CM levels of Mfn2.Increasing CM levels of Mfn2 prevented the increase in CM mitochondrial oxidant production.3.Increase CM Mfn2 or pretreatment of CM with anti-oxidant,Mitotempo,prevented the DOX-induced cardiomyocyte apoptosis.ConclusionIn the DOX-induced cardiomyocyte apoptosis,the down-regulation of Mfn2 expression in cardiomyocytes plays an important role,and this effect is related to the production of intracellular damage to reactive oxygen species.Mitotempo mitochondrial-specific antioxidant can inhibit DOX-induced Cardiomyocyte apoptosis.