Stimulation of arachidonic-acid release from Swiss 3T3 cells by recombinant basic fibroblast growth factor: independence from phosphoinositide turnover.
In this study we have attempted to characterize the mechanism of recombinant bovine basic fibroblast growth factor (rbFGF)-induced release of arachidonic acid from prelabelled Swiss 3T3 fibroblasts. Recombinant bFGF caused the release of [3H]arachidonic acid from metabolically labelled cells in a dose- and time-dependent manner. This effect was maximal with 10 ng rbFGF/ml and became significant after a 30-min incubation. Although rbFGF was able to cause a modest increase in total inositol phosphate accumulation, an examination of the time-course of the latter effect revealed that enhanced [3H]arachidonic-acid release could not have been derived from phosphoinositide metabolism. Evidence suggesting that rbFGF-induced release of [3H]arachidonic acid was being mediated via a PLA2 pathway was obtained by pharmacological antagonism using mepacrine, a putative PLA2 inhibitor. Moreover, treatment of cells with neomycin failed to attenuate rbFGF-mediated release of [3H]arachidonic acid. Chelation of extracellular calcium by EGTA was found to abrogate rbFGF-induced liberation of [3H]arachidonic add. Down-regulation of protein kinase C (PKC) by prolonged treatment of cells with the phorbol ester, PMA, was observed to have no effect on the action of rbFGF on [3H]arachidonic add release from Swiss 3T3 fibroblasts. While rbFGF was found to cause the indomethacin-sensitive production of prostaglandin E2 (PGE2) in a dose-dependent manner, this effect was independent of rbFGF-induced reinitiation of DNA synthesis. Clearly, the effect of rbFGF on cellular DNA synthesis was being mediated independently of PGE2 biosynthesis. We discuss the potential importance of the PLA2-signalling pathway in the mechanism of action of fibroblast growth factors.
Virdee
K
K
Department of Human Metabolism and Clinical Biochemistry, University of Sheffield Medical School, UK.
Brown
B L
BL
Dobson
P R
PR
D016475:3T3 Cells / Q000187:drug effects; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D004247:DNA / Q000096:biosynthesis; D015232:Dinoprostone / Q000096:biosynthesis; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D051379:Mice; D009355:Neomycin / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism*; D011796:Quinacrine / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D013997:Time Factors; D014316:Tritium
D010716:Phosphatidylinositols; D011994:Recombinant Proteins; D014316:Tritium; D016222:Fibroblast Growth Factor 2; D016718:Arachidonic Acid; D004247:DNA; D011796:Quinacrine; D009355:Neomycin; D015232:Dinoprostone