Phosphorylation of STAT-3 in response to basic fibroblast growth factor occurs through a mechanism involving platelet-activating factor, JAK-2, and Src in human umbilical vein endothelial cells. Evidence for a dual kinase mechanism.
Platelet-activating factor (PAF) is a potent proinflammatory phospholipid with multiple pathological and physiological effects. We have shown that basic fibroblast growth factor (bFGF) supplementation induces rapid proliferation of human umbilical vein endothelial cells (HUVEC), which is reduced upon removal of bFGF or by bFGF immunoneutralization. The PAF receptor antagonist LAU-8080 inhibited bFGF-stimulated HUVEC proliferation, indicating the involvement of PAF in the bFGF-mediated signaling of HUVEC. Although FGF receptor phosphorylation was not affected by LAU-8080, the bFGF-mediated prolonged phosphorylation, and activation of Erk-1 and -2 were attenuated. Phosphorylation of STAT-3 was observed in the presence of PAF or bFGF, which was attenuated by PAFR antagonists. PAF-induced STAT-3 phosphorylation observed in HUVEC pretreated with either Src inhibitor PP1 or JAK-2 inhibitor AG-490 indicated (i) immediate (1 min) phosphorylation of STAT-3 is dependent on Src, (ii) JAK-2-dependent STAT-3 phosphorylation occurs after the delayed (30 min) PAF exposure, and (iii) prolonged (60 min) STAT-3 phosphorylation may be either through Src and/or JAK-2. Attenuation of the STAT-3 phosphorylation by the PAFR antagonists indicated signaling through the PAF receptor. Taken together, these findings suggest the production of PAF is important for bFGF-mediated signaling and that a dual kinase mechanism is involved in the PAF-mediated signal transduction cascade.
Deo
Dayanand D
DD
Department of Biochemistry and Molecular Biology, Stanley S. Scott Cancer Center and Neuroscience Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
Axelrad
T William
TW
Robert
Everett G
EG
Marcheselli
Victor
V
Bazan
Nicolas G
NG
Hunt
Jay D
JD
D015153:Blotting, Western; D002455:Cell Division; D002465:Cell Movement; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D003720:Densitometry; D004789:Enzyme Activation; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D006801:Humans; D053614:Janus Kinase 2; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D010766:Phosphorylation; D010972:Platelet Activating Factor / Q000378:metabolism; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D017468:Receptors, Fibroblast Growth Factor / Q000378:metabolism; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D013997:Time Factors; D015534:Trans-Activators / Q000737:chemistry* / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology; D019061:src-Family Kinases / Q000378:metabolism
D004268:DNA-Binding Proteins; D010972:Platelet Activating Factor; D011518:Proto-Oncogene Proteins; D017468:Receptors, Fibroblast Growth Factor; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D015534:Trans-Activators; D016222:Fibroblast Growth Factor 2; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D019061:src-Family Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases