Role of ABCA1 in angiotensin Ⅱ-induced cholesterol accumulation in podocytes / 中华肾脏病杂志

ABSTRACT

Objective To investigate the effects of angiotensin Ⅱ (Ang Ⅱ) on the expression of ATP-binding cassette transporter A1(ABCA1) in Ang Ⅱ-infused rat model and cultured human podocytes,and to explore the role of ABCA1 in Ang Ⅱ-induced cholesterol accumulation of podocytes.Methods Twelve Wistar rats were randomly subjected to normal saline infusion,or Ang Ⅱ infusion at 400 ng· kg-1 · min-1 (via subcutaneous osmotic minipumps) for 8 weeks.The expression of glomerular ABCA1 was analyzed by Western blotting and real-time fluorescent quantitative PCR.In vitro,conditionally immortalized human podocytes were divided into normal group,Ang Ⅱ group,Ang Ⅱ + scrambled siRNA group,Ang Ⅱ + ABCA1 siRNA group.The expression of podocyte ABCA1 was assessed by immunofluorescence,Western blotting and real-time fluorescent quantitative PCR.Oil Red 0 staining was used to observe the lipid droplets in podocytes and cholesterol efflux assay kit was used to measure the cholesterol efflux rate of podocytes.Fluorescein isothiocyanate (FITC)-conjugated phalloidin was used to observe the podocyte cytoskeleton.Results In vivo,compared with normal group,the protein and mRNA expression of glomerular ABCA1 in Ang Ⅱ-infused rats were decreased (P ＜ 0.05).In vitro,ABCA1 was distributed in the cytomembrane of podocytes,and compared with normal group,Ang Ⅱ treatment down-regulated the expression of ABCA1 (P ＜ 0.05).Increased lipid droplets,decreased cholesterol efflux and cytoskeletal rearrangement were observed in Ang Ⅱ-treated podocytes.When compared to Ang Ⅱ group,podocytes stimulated by Ang Ⅱ and then transfected with ABCA1 siRNA had lower expression level of ABCA1 mRNA and protein (all P ＜ 0.05).More lipid droplets and lower cholesterol efflux rate could be observed in Ang Ⅱ +ABCA1 siRNA group (P＜ 0.05).Conclusion The reduced expression of ABCA1 may be involved in Ang Ⅱ-induced cholesterol accumulation in podocytes.