| BackgroundDiabetes is a chronic metabo lic disorder,which makes great threat against the human health,and its cardiovascular complications are the main cause of death in patients with diabetes. Diabetic cardiomyopathy is characterized by the changes in the cardiac structure and function, accompanied with myocardium hypertrophy, apoptosis and myocardial interstitial fibrosis,and leads to the death with heart failure.It is an important problem to be solved to reduce the cardiomyocytes injur ies induced by diabetes and to improve the prognosis of the patients. Aldehyde dehydrogenase 2(ALDH2) is a kind of oxidase in mitochondria, which can participate in the metabolism of acetaldehyde and reduce the damages caused by aldehyde.It has been reported that ALDH2 involves in the regulation of a variety of signaling pathways in cells and protects the cardiomyocytes from the injuries. Alda- 1 can activate ALDH2 selectively,and alleviates the cell death induced by ischemia reperfusion injury. Autophagy is a cellular process to maintain the homeostasis by removing the aging or injured organelles or proteins,and is associated with heart diseases.However,the effect of ALDH2 on the cardiomyocytes and autophagy with hyperglycemia is still unclear and the mechanism need to be explored. ObjectivesThe purpose of the research was to explore the effect of ALDH2 on diabetic cardiomyopathy induced by streptozotocin and on high glucose- induced cardiomyocytes injuries.The cell apoptosis and the mitochondrial membrane potential were examined,and the autophagy markers were also measured.It was needed to confirm whether the protective effect of ALDH2 was obtained from the regulation of autophagy and to explore the possible mechanism. MethodsThe research was employed to explore the effect of ALDH2 on diabetic cardiomyopathy.The ALDH2 overexpression mice and friendly virus B mice were injected with stretozotocin in order to establish diabetic models.Then the cell shortening and relengthening were measured,as well as the intracellular Ca2+ transient.The H9C2 cells were treated with high dose(33 m M) of glucose for 72 hours, with the presence or absence of ALDH2 activator Alda-1(20 μM).The autophagy inhibitor 3-MA(10 m M) or Bafilomycin A1(BAF,50 n M)or the autophagy inducer rapamycin(Rap, 100 n M) was also employed. The apoptosis was measured with TUN EL assay. JC-1 Assay K it was submitted to explore the mitochondrial membrane potential. Western blotting was used to assess the expression of protein p62, LC3 B or the phosphorylation of ULK1.The cells were transfected with plasmid expressing GFP-LC3 fusion protein to examine the number of the autophagosome. ResultsALDH2 overexpression significantly alleviated the stretozotocin- incudced myocuytes dysfunction including the peak shortening and the increased myocytes area.The maximal velocity of relengthening was depressed by streptozotocin,which was reversed by ALDH2 overexpresssion. High glucose induced cell death indicated by TUN EL assay.And the mitochondrial membrane potentials were damaged with high glucose exposure.All these consequences were eliminated by ALDH2 with the up-regulation of autophagy.The expression of autophagy protein marker LC3 BII and the LC3 B II-to-LC3 B I ratio were decreased and the level of p62 was elevated in hyperglycemic condition,and these results were reversed by ALHD2. The autophagy inhibitor 3-MA and lysosomal inhibitor bafilomycin A1 reconciled the ALDH2-offered protection against high glucose,which was imitated by rapamycin.The phosphorylation levels of ULK1 were up-regulated by ALHD2 with high glucose treatment.Moreover,knock-down of ULK1 using si RNA in H9C2 cells abolished the autophagosome accumulation and LC3 expression caused by ALDH2.And autophagy dampened under high glucose condition was also demonstrated by GFP-LC3 puncta. ConclusionTaken together,these data suggested that ULK1 played a crucial role in ALDH2-offered protective effect against diabetic cardiac injuries through regulation of autophagy. |
PDF Full Text Request