Expression of angiogenesis regulatory factors and their receptors in mouse kidneys with aging / 中华肾脏病杂志

ABSTRACT

Objective To investigate the expression of vascular endothelial growth factor (VEGF), angiopoietin and their receptors (VEGFR and Tie2) in aging mice kidney and the possible roles in aging mice. Methods Mice were divided as follows 4-month old group (n=6), 9-month old group (n=6), 12-month old group (n=6) and 20-month old group (n=6). Paraffin sections of the mice kidneys were stained by PAS. The density of glomerular microvascular was determined by renal perfusion with fluorescent dyes. The level of VEGF, VEGFR2 (Flk-1), Ang-1, Ang-2, Tie2 mRNA expression and protein abundance in kidney was determined by real-time PCR, immunochemistry, immunofluorescence and Western blot. Results Compared with other three groups, in the 20-manth old group, the glomerulosclerosis index (GSI) increased remarkbly (2.48±0.79 vs 0.53±0.19, 0.69±0.18, 1.50±0.70, P<0.05); the fluorescence intensity in glomeruli decreased (P<0.05). lmmunohistochemistry demonstrated that the TGF-131 level in the aging kidneys showed an increase trend in the glomerular tubulointerstitium, and especially in the glomeruli. Real-time PCR results revealed that compared with 4-month old group mice, the mRNA expression of VEGF, Flk-1, Ang-1, Ang-2, Tie2 of the other three groups decreased, the gene levels of VEGF, Flk-1, and Ang-2 fell about 90%, 50% and 80% (all P>0.05), and the gene levels of Ang-1 and Tie2 fell about 75% and 40% in 20-month-old group (all P<0.05). Western blot domonstrated that the protein abundace of VEGF, Flk-1, Ang-1, Ang-2, Tie2 also declined with aging, the protein level of VEGF, Flk-1, Ang-1, Ang-2 and Tie2 dropped by about 35%, 50%, 15%, 13% and 21% respectively in 20-month-old group as compared to 4-month-old group (all P<0.05). Expression of above 5 factors and glomerular fluorescence intensity were negatively correlated with Scr (P<0.05). Conclusions The mRNA expression and protein abundance of VEGF, Flk-1, Ang-1, Ang-2, Tie2 in mice kidneys decreases with aging. Angiogenesis regulatory factors may play important roles in aging progression of the mice kidney.