1. Platelet-activating factor induces ovine fetal pulmonary venous smooth muscle cell proliferation: role of epidermal growth factor receptor transactivation.
- Author
-
Zhou W, Ibe BO, and Raj JU
- Subjects
- Animals, Bacterial Proteins pharmacology, Cells, Cultured, Dipeptides pharmacology, Dose-Response Relationship, Drug, Enzyme Activation, Enzyme Inhibitors pharmacology, Epidermal Growth Factor genetics, ErbB Receptors drug effects, ErbB Receptors genetics, Extracellular Signal-Regulated MAP Kinases metabolism, Heparin-binding EGF-like Growth Factor, Intercellular Signaling Peptides and Proteins, Matrix Metalloproteinase 2 metabolism, Matrix Metalloproteinase 9 metabolism, Matrix Metalloproteinase Inhibitors, Muscle, Smooth, Vascular cytology, Muscle, Smooth, Vascular drug effects, Muscle, Smooth, Vascular embryology, Mutation, Myocytes, Smooth Muscle drug effects, Phosphorylation, Platelet Activating Factor pharmacology, Pulmonary Veins cytology, Pulmonary Veins embryology, Pulmonary Veins metabolism, Quinazolines, Sheep, Time Factors, Transfection, Tyrphostins pharmacology, p38 Mitogen-Activated Protein Kinases metabolism, Cell Proliferation drug effects, Epidermal Growth Factor metabolism, ErbB Receptors metabolism, Muscle, Smooth, Vascular metabolism, Myocytes, Smooth Muscle metabolism, Platelet Activating Factor metabolism, Signal Transduction drug effects
- Abstract
We have previously reported that platelet-activating factor (PAF) is present in very high levels in the ovine fetal lung and circulation and that PAF serves as an important physiological vasoconstrictor of the pulmonary circulation in utero. However, it is not known whether PAF stimulates pulmonary vascular smooth muscle cell (SMC) proliferation. In this study, we used ovine fetal pulmonary venous SMCs as our model system to study the effects and mechanisms of action of PAF on SMC proliferation. We found that PAF induced SMC proliferation in a dose-dependent manner. PAF also stimulated activation of both ERK and p38 but not c-Jun NH(2) terminal kinase (JNK) mitogen-activated protein (MAP) kinase pathways. PAF (10 nM) induced phosphorylation of epidermal growth factor receptor (EGFR). Specific inhibition of EGFR by AG-1478 and by the expression of a dominant-negative EGFR mutant in SMCs attenuated PAF-stimulated cell proliferation. Inhibition of heparin-binding EGF-like growth factor (HB-EGF) release by CRM-197 and inhibition of matrix metalloproteinases (MMP) by GM-6001 abolished PAF-induced MAP kinase activation and cell proliferation. Increased alkaline phosphatase (AP) activity after PAF treatment in AP-HB-EGF fusion construct-transfected SMCs indicated that PAF induced the release of HB-EGF within 1 min. Gelatin zymography data showed that PAF stimulated MMP-2 activity and MMP-9 activity within 1 min. These results suggest that PAF promotes pulmonary vascular SMC proliferation via transactivation of EGFR through MMP activation and HB-EGF, resulting in p38 and ERK activation and that EGFR transactivation is essential for the mitogenic effect of PAF in pulmonary venous SMC.
- Published
- 2007
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