Effects of Sirt1 gene knockout on chronic kidney disease induced by 5/6 nephrectomy in mice and VEGF/Flk-1 signaling pathway / 中华肾脏病杂志

ABSTRACT

Objective To investigate the effect of Sirt1 gene knockout on chronic kidney disease induced by 5/6 nephrectomy in mice and vascular endothelial growth factor (VEGF)/fetal liver kinase-1 (Flk-1) signaling pathway.Methods Twenty four male Sirt1 +/+ and Sirt1 +/-mice wererandomly divided into four groupsSirt1+/+ mice with sham-operation (WT-Sham,n=6),Sirt1+/-mice with sham-operation (KO-Sham,n=6),Sirt1 +/+ mice with 5/6 nephrectomy (WT-Nx,n=6) and Sirt1 +/-mice with 5/6 nephrectomy (KO-Nx,n=6).Proteinuria was determined by urine collection from 800 to 800 the next day at 20 weeks.Serum creatinine (Scr),urea nitrogen (BUN) and the renal pathological changes were measured after 20 weeks.Expressions of Sirt1,collagen Ⅰ and transforming growth factor β(TGF-β) were used to analyze the changes of renal fibrosis by immunohistochemistry staining.Real-time PCR and Western blotting were used to measure the mRNA and protein expressions of Sirt1,fibronectin,collagen Ⅰ,VEGF and Flk-1 in kidney.Results Sirt1 expressed in glomernlar endothelial cells,podocytes,mesangial cells and renal tubular epithelial cells in Sirt1 +/+ mice,while Sirt1 expression intensity was significantly reduced in Sirt1 +/-mice.Compared with the WT-Sham group,WT-Nx group had increased proteinuria,BUN,Scr,glomernlar sclerosis index and tubulointerstitial fibrosis index at 12 weeks after operation (all P ＜ 0.01),and KO-Nx group had exacerbated the above up-regulations (all P ＜ 0.01).Compared with those in WT-Sham group,the expressions of fibronectin,collagen Ⅰ and TGF-β were up-regulated in WT-Nx group (all P ＜ 0.01),and were significantly augmented in KO-Nx group (all P ＜ 0.01).Compared with those in WT-Sham group,renal mRNA and protein expressions of VEGF and Flk-1 were decreased in WT-Nx group,and KO-Nx group aggravated their down-regulation (all P ＜ 0.01).Conclusions Sirt1 gene knockout can increase proteinuria and Scr,and aggravate renal pathology and renal fibrosis in 5/6 nephrectomized mice,which is associated with the inhibition of VEGF/Flk-1 signaling pathway.It is suggested that Sirt1 may be a potential therapeutic target of chronic kidney disease.