Activation of Multiple Signaling Pathways Is Critical for Fibroblast Growth Factor 2- and Vascular Endothelial Growth Factor-Stimulated Ovine Fetoplacental Endothelial Cell Proliferation

• Published in: Biology of reproduction 2008, Vol.78 (1), p.143-150
• Main Authors: Zheng, Jing, Wen, YunXia, Song, Yang, Wang, Kai, Chen, Dong-Bao, Magness, Ronald R
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cell Line; Cell Proliferation - drug effects; Chromones - pharmacology; Cyclic N-Oxides - pharmacology; Embryology: invertebrates and vertebrates. Teratology; Endothelial Cells - cytology; Endothelial Cells - drug effects; Enzyme Inhibitors - pharmacology; Fetal membranes; Fetus - cytology; Fibroblast Growth Factor 2 - pharmacology; Flavonoids - pharmacology; Fundamental and applied biological sciences. Psychology; General aspects. Development. Fetal membranes; Imidazoles - pharmacology; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - metabolism; Morpholines - pharmacology; Nitric Oxide - metabolism; omega-N-Methylarginine - pharmacology; Phosphatidylinositol 3-Kinases - metabolism; Phosphorylation - drug effects; Placenta - cytology; Proto-Oncogene Proteins c-akt - metabolism; Sheep; Signal Transduction - drug effects; Vascular Endothelial Growth Factor A - pharmacology
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.107.064477

Fibroblast growth factor-2 (FGF2) and vascular endothelial growth factor (VEGF) are two key regulators of placental angiogenesis. The potent vasodilator nitric oxide (NO) could also act as a key mediator of FGF2- and VEGF-induced angiogenesis. However, the postreceptor signaling pathways governing these FGF2- and VEGF-induced placental angiogenic responses are poorly understood. In this study, we assessed the role of endogenous NO, mitogen-activated protein kinase 3/1 (MAPK3/1), and v-akt murine thymoma viral oncogene homolog 1 (AKT1) in FGF2- and VEGF-stimulated proliferation of ovine fetoplacental endothelial (OFPAE) cells. Both FGF2 and VEGF time-dependently stimulated (P < 0.05) NO production and activated AKT1. Both FGF2- and VEGF-stimulated cell proliferation was dose-dependently inhibited (P < 0.05) by NG-monomethyl-L-arginine (L-NMMA; an NO synthase inhibitor), PD98059 (a selective MAPK3/1 kinase 1 and 2 [MAP2K1/2] inhibitor), or LY294002 (a selective phosphatidylinositol 3 kinase [PI3K] inhibitor) but not by phenyl-4,4,5,5 tetramethylimidazoline-1-oxyl 3-oxide (PTIO, a potent extracellular NO scavenger). At the maximal inhibitory dose without cytotoxicity, PD98059 and LY294002 completely inhibited VEGF-induced cell proliferation but only partially attenuated (P < 0.05) FGF2-induced cell proliferation. PD98059 and LY294002 also inhibited (P < 0.05) FGF2- and VEGF-induced phosphorylation of MAPK3/1 and AKT1, respectively. L-NMMA did not significantly affect FGF2- and VEGF-induced phosphorylation of either MAPK3/1 or AKT1. Thus, in OFPAE cells, both FGF2- and VEGF-stimulated cell proliferation is partly mediated via NO as an intracellular and downstream signal of MAPK3/1 and AKT1 activation. Moreover, activation of both MAP2K1/2/MAPK3/1 and PI3K/AKT1 pathways is critical for FGF2-stimulated cell proliferation, whereas activation of either one pathway is sufficient for mediating the VEGF-induced maximal cell proliferation, indicating that these two kinase pathways differentially mediate the FGF2- and VEGF-stimulated OFPAE cell proliferation.