Common and distinct pathways for cellular activities in FGF-2 signaling induced by IL-1beta in corneal endothelial cells.
OBJECTIVE
To determine the mechanism by which IL-1beta induces FGF-2 and to elucidate the signaling pathways of IL-1beta-induced FGF-2 in corneal endothelial cells (CECs).


METHODS
Expression and/or activation of FGF-2, p38, ERK1/2, and Akt was analyzed by immunoblot analysis. Cell proliferation was measured by MTT assay. Pharmacologic inhibitors were used to block PI 3-kinase, p38, or ERK1/2.


RESULTS
Brief stimulation of CECs with IL-1beta activated PI 3-kinase and p38 in a biphasic fashion. The first wave of activation, triggered by IL-1beta, involves the inductive activity of IL-1beta on FGF-2 production; the second wave of activation, triggered by the induced FGF-2, involves the promotion of cellular activities. In both pathways, p38 acts downstream to PI 3-kinase. The inductive activity of IL-1beta on FGF-2 is further evidenced by the conditioned medium, which contains a large amount of FGF-2. Stimulation of CECs with IL-1beta also activated ERK1/2 in a delayed fashion. The IL-1beta-induced FGF-2 exerted cellular activities using distinct pathways: the second wave of activation of PI 3-kinase and p38 was involved in cell migration, whereas cell proliferation was simultaneously stimulated by ERK1/2 and the second wave of PI 3-kinase. Likewise, the conditioned medium demonstrated cellular activities and pathways identical with those observed in cells treated with IL-1beta.


CONCLUSIONS
These data suggest that CECs produce FGF-2 by IL-1beta stimulation through PI 3-kinase and p38. The IL-1beta-induced FGF-2 facilitates cell migration via PI 3-kinase and p38, whereas it stimulates cell proliferation using PI 3-kinase and ERK1/2 in parallel pathways.
Lee
Jeong Goo
JG
Doheny Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, California 90033, USA.
Kay
EunDuck P
EP
D000818:Animals; D018929:Cell Culture Techniques; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation; D004728:Endothelium, Corneal / Q000187:drug effects* / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D015151:Immunoblotting; D053583:Interleukin-1beta / Q000494:pharmacology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011817:Rabbits; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D004791:Enzyme Inhibitors; D053583:Interleukin-1beta; D016222:Fibroblast Growth Factor 2; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases