Ubiquitin Ligase MuRF2 Inhibits Mitochondrial Autophagy In Cardiomyocytes

Objective To assess the role of E3 ubiquitin ligase muscle ring finger protein 2(MuRF2)in cardiomyocyte autophagy.Methods By means of lentiviral transfection technique,we upregulated and down-regulated the expression of MuRF2 in HL-1 cardiomyocytes.Cells were grouped as negative control,positive control,Rapamycin treatment group,MuRF2 overexpression and MuRF2 knockdown.The cells were treated with Rapamycin and the expressions of autophagy proteins LC3 and BNIP3 were detected by Western blot.The ultrastructure of HL-1 cardiomyocytes were observed by transmission electron microscopy(TEM).Results (1)Western blot validation showed that the expression level of MuRF2 protein in MuRF2 overexpression group was higher than that in the negative control group?positive control group and in the rapamycin treatment group,(P <0.05).the expression level of MuRF2 protein in the MuRF2 knockdown group was significantly lower than that in the negative control group?the positive control group and rapamycin treatment group,(P <0.05)?(2)LC3II/I and BNIP3 protein expression in rapamycin treatment group were higher than negative control,(P< 0.05).In MuRF2 overexpression group,LC3II/I and BNIP3 protein expression were lower than that in rapamycin treatment group(P< 0.05).Compared with the negative control group,LC3II/I and BNIP3 protein expression in rapamycin treatment group and MuRF2 knockdown group were higher.There is no difference between rapamycin treatment group and MuRF2 knockdown,(P>0.05).TEM analysis showed the Rapamycintreatment group.Mitochondria were being fission and fragmented,autophagosomes and autophagolysosomes scattered in the cytoplasm.In MuRF2 overexpression group,mitochondria were in fusion status and autophagosomes much less.Conclusion MuRF2 inhibits mitochondrial autophagy in HL-1 cardiomyocytes.