P3485Autophagy insufficiency participates in hyperhomocysteinemia-induced cardiac aging

Abstract

Abstract Background The elevated plasma homocysteine (Hcy) level can lead to severe cardiovascular injuries, which participates in the progression of atherosclerosis, heart failure and so on. Except cardiovascular diseases, accumulated researches further revealed that hyperhomocystenemia (HHcy) can also induce aging-related diseases, including Alzheimer's disease, Parkinson's disease, diabetic cardiomyopathy, etc. Though some researches had revealed that Hcy stimulation would lead to endothelial cells senescence, whether cardiac aging could be induced by HHcy still remain unknown. Purpose This study aimed to reveal whether HHcy can induce cardiac aging and the underlying mechanisms. Methods SD rats were utilized to establish HHcy rat model and natural aging rat model. The cardiac function were determined by Echocardiography. Transmission electron microscope were used to detect mitochondria injuries of myocardium. 18F-FDG PET/CT was used to detect the state of glucose metabolism in myocardial cells. Agilent mRNA Array was used to detect possible altered pathways in myocardium of HHcy rats. The autophagy level was determined by detection of both autophagy-related proteins expressions with Western Blot and autophagic flux with mRFP-GFP-LC3. Results HHcy rats showed overall aging phenotypes, which were consistent with natural aging rats. The impaired cardiac function and severely injured myocardium morphology were observed in HHcy rats. Aging-related markers were increased significantly in HHcy rats and Hcy-treated cells, presented as increased p16, p21 and p53 expressions and increased senescence-associated beta-galactosidase (SA-β-gal) activity. Mitochondria dysfunction and morphology injuries were also detected in HHcy rats. Moreover, decreased serum Beclin-1 level was tested in CHD patients with HHcy. The decreased autophagy level was further verified in HHcy rats and Hcy-treated cells. Furthermore, the over-expression of Atg5 could attenuate Hcy induced cellular senescence. Conclusion HHcy can reduce autophagy level, which leading to severe mitochondria injuries, and resulted in cardiac aging eventually. Acknowledgement/Funding Natural Science Foundation of China (81671382,91839107)