[Altered expression of vascular endothelial growth factor and its receptors in transdifferentiated human proximal tubular epithelial cells induced by transforming growth factor beta1].
OBJECTIVE
To examine the expression of vascular endothelial growth factor (VEGF) and its receptors (VEGFR1, VEGFR2) in transdifferentiated human proximal tubular epithelial (HK-2) cell induced by transforming growth factor beta1 (TGFbeta1).


METHODS
The transdifferentiation of HK-2 cells was detected by evaluation of expression of alpha-SMA by cytoimmunochemistry and RT-PCR. The VEGF mRNA was evaluated with RT-PCR. The secreted VEGF in the culture media was measured with ELISA. The cellular VEGF, VEGFR1, and VEGFR2 were measured with Western blot.


RESULTS
The immunostain of alpha-SMA were positive in HK-2 cell induced by TGFbeta1 at the concentration of 5 and 8 ng/ml for 72 h. The expression of alpha-SMA mRNA was induced by TGFbeta1 in concentration- and time-dependent manners. The expressions of mRNA and protein of VEGF were upregulated by TGFbeta1 at the concentration of 0.1 and 1 ng/ml for 72 h and at the concentration of 8 ng/ml for 12 h and 24 h when compared with the control. But expressions of mRNA and protein of VEGF were downregulated by TGFbeta1 at the concentration of 3, 5, and 8 ng/ml for 72 h and at the concentration of 8 ng/ml for 36, 48, and 72 h, respectively. Meanwhile, Protein levels of VEGFR1 and VEGFR2 were upregulated by TGFbeta1 in concentration- and time- dependent manners.


CONCLUSIONS
Increased expression of VEGFR1 and VEGFR2 and two-phase change in VEGF expression occurred in the process of tubular epithelial transdifferentiation induced by TGFbeta1. Reduced expression of VEGF may contribute to tubular epithelial transdifferentiation in a vicious circle.
Zhou
Qiu-gen
QG
Department of Nephrology, PUMC Hospital, CAMS and PUMC, Beijing 100730, China.
Zheng
Fa-lei
FL
Wen
Yu-bing
YB
Tan
Xiao-yue
XY
Duan
Lin
L
Li
Yan
Y
D002454:Cell Differentiation; D004847:Epithelial Cells / Q000166:cytology; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology*; D012333:RNA, Messenger / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
D012333:RNA, Messenger; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A; D040262:Receptors, Vascular Endothelial Growth Factor; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2