Angiotensin II stimulates the synthesis of vascular endothelial growth factor through the p38 mitogen activated protein kinase pathway in cultured mouse podocytes.
Angiotensin II (Ang-II) and vascular endothelial growth factor (VEGF) have an important role in the pathogenesis of diabetic nephropathy, but the signaling cascade of VEGF regulation in response to Ang-II in podocytes is largely unknown. In these experiments, we looked at the effect of Ang-II on the production of VEGF, and investigated whether VEGF production depends on the p38 mitogen activated protein kinase (MAPK) pathway in cultured mouse podocytes. Incubation of podocytes with Ang-II induced a rapid increase in VEGF mRNA expression and protein synthesis as well as its transcriptional activity in an Ang-II dose-dependent manner. To further define the role of angiotensin type 1 (AT1) and type 2 (AT2) receptors involved in Ang-II-mediated VEGF synthesis, the effects of selective AT1 and AT2 receptor antagonists were evaluated. Prior treatment with losartan significantly inhibited VEGF mRNA and protein synthesis induced by Ang-II, which suggests that the AT1 receptor is involved in Ang-II-mediated VEGF synthesis. Furthermore, stimulation of the cells with Ang-II increased both phosphorylation of p38 MAPK and MAP kinase kinase 3/6 (MKK3/6). Additionally, Ang-II enhanced the DNA binding activity to cAMP response element binding protein (CREB) and phosphorylation of CREB. In addition, to investigate the role of p38 MAPK in Ang-II-induced VEGF synthesis, podocytes were pretreated with or without the p38 MAPK inhibitor, SB203580 for 24 h to observe whether Ang-II-mediated VEGF synthesis was inhibited by blocking p38 MAPK. The addition of SB203580 led to a marked inhibition of the increased VEGF mRNA and protein production induced by Ang-II in a dose-dependent manner. Taken together, these results suggest that Ang-II stimulates the synthesis of VEGF in podocytes and the production of VEGF induced by Ang-II is mediated, in part, through the activation of the p38 MAPK pathway.
Kang
Young Sun
YS
Department of Internal Medicine, Korea University Hospital, 516 Kojan-Dong, Ansan City, Kyungki-Do 425-020, Korea.
Park
Yun Gyu
YG
Kim
Bo Kyung
BK
Han
Sang Youb
SY
Jee
Yi Hwa
YH
Han
Kum Hyun
KH
Lee
Mi Hwa
MH
Song
Hye Kyoung
HK
Cha
Dae Ryong
DR
Kang
Shin Wook
SW
Han
Dae Suk
DS
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation / Q000187:drug effects; D007093:Imidazoles / Q000494:pharmacology; D048371:MAP Kinase Kinase 3 / Q000378:metabolism; D048669:MAP Kinase Kinase 6 / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D020218:Response Elements; D015533:Transcriptional Activation / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D007093:Imidazoles; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D000804:Angiotensin II; D048051:p38 Mitogen-Activated Protein Kinases; D048371:MAP Kinase Kinase 3; D048669:MAP Kinase Kinase 6; C482531:Map2k3 protein, mouse; C482567:Map2k6 protein, mouse; C093642:SB 203580