Angiotensin Ii To Stimulate The Human Podocyte Expression Of Vascular Endothelial Growth Factor Signaling Pathway

OBJECTIVE:To study the effect of AngiotensinⅡ(AngⅡ) on the expression of vascular endothelial growth factor(VEGF) and investigate the mechanism of VEGF expressiom stimulated by AngⅡ,whether VEGF expression depends on the p38 mitogen activated protein kinase(MAPK) pathway in cultured human podocytes.METHODS:Incubation of podocytes with AngⅡ(1nM,10nM,100nM) for 24 hours,we observed the expression of VEGFmRNA levels of podocytes by RT-PCR.On the basis of these experimental results,we selected concentration of AngⅡincubated with podocytes for 3,6,12,24 hours and measured VEGFmRNA levels of podocytes by RT-PCR.Podocytes were pretreated with the different doses rat serum containing losartan and 100nM AngⅡfor 24 hours, respectively measured VEGFmRNA levels of podocytes by RT-PCR.Prior treatment with p38MAPK inhibitor SB203580(1μM,5μM,10μM) for one hours,podocytes were treated with 100nM AngⅡfor 24 hours,using RT-PCR and Western blot methods,we observed the expression of VEGFmRNA and protein and p38MAPK protein levels of podocytes.RESULTS:Podocytes incubated with AngⅡwere increasing dramatically in VEGFmRNA expression as well as its transcriptional activity in an AngⅡdose-dependent and time-dependent manner,10nM,100nM AngⅡstimulated podocytes and 100nM AngⅡstimulated podocytes for3,6,12,24hours compared with the normal control group had statistical significance(p＜0.05).Losartan significantly inhibited VEGFmRNA stimulated by AngⅡ,whereas high and medium dose groups compared with the stimulated group had statistical significance(p＜0.05).The addition of SB203580 led to a marked inhibition of the increased p38MAPK protein expression stimulated by AngⅡ,1,5,10μM SB203580 group compared with the stimulated group had statistical significance(p＜0.05),the expression of VEGFmRNA and protein also were inhibited in an AngⅡdose-dependent manner,1,5,10μM SB203580 group compared with the stimulated group had statistical significance(p＜0.05).CONCLUSION:AngⅡstimulates the expression of VEGF in cultured human podocytes and partly mediates the expression of VEGF through the activation of the p38MAPK pathway.