Role of autophagy in high glucose-induced podocyte lipid droplet accumulation

Objective To investigate the role of autophagy in high glucose-induced podocyte lipid droplet metabolism. Methods (1) Cultured, conditionally immortalized human podocytes (HPC) were divided into normal control group, high glucose group and mannitol group. Oil red O staining and oil red O staining extraction assay was used to observe the degree of lipid accumulation; Protein level of SREBP-1 was analyzed by Western blotting. (2) HPC were cultured and divided into normal control group, high glucose group, high glucose+3-methyladenine (3-MA) group, and mannitol group. Acridine orange staining was used to observe the formation of autophagosomes. Western blotting was used to detect the protein levels of beclin-1 and LC3-II/LC3-I. Oil red O staining and oil red O staining extraction assay was used to observe the degree of lipid accumulation; Western blotting was used to analyze the expression of SREBP-1. Results (1) Compared with the normal control group, the lipid accumulation in the high glucose group was increased and the lipid metabolism related molecule SREBP-1 was up-regulated (P＜0.05); There was no significant difference between the normal control group and the mannitol group in lipid accumulation (P＞0.05). (2) Compared with the normal group, the number of autophagosomes was increased and autophagy-related proteins beclin-1 and LC3-II/LC3-I were up-regulated in high glucose group (all P＜0.05). After intervened with 3-methyladenine, a significant decrease in autophagosomes was observed; Protein levels of autophagy-related proteins beclin-1 and LC3-II/LC3-I were decreased (all P＜0.05); The lipid droplets in the high glucose+3-MA group was decreased and lipid metabolism related molecule SREBP-1 was down-regulated (all P＜0.05). Conclusion Autophagy may be involved in the process of high-glucose-induced podocyte lipid accumulation by affecting SREBP-1 expression, and inhibition of autophagy can alleviate the high-glucose-induced podocyte lipid accumulation.