The mitogenic action of recombinant basic FGF in Swiss 3T3 cells is independent of early diradylglycerol production and downregulatable protein kinase C activity.
In this study we have investigated the requirement for phosphoinositide metabolism, diradylglycerol (DG) production and protein kinase C (PKC) activation in recombinant basic fibroblast growth factor (rbFGF)-mediated reinitiation of DNA synthesis in Swiss 3T3 cells. We have assessed the involvement of PKC activation in rbFGF-induced DNA synthesis by two approaches; enzymic inhibition by H7 and down-regulation by prolonged phorbol-ester treatment. In both conditions we observed that rbFGF was able to sustain a significant component of its mitogenic response, therefore denying an exclusive role for the activation of downregulatable and H7-sensitive PKC isoforms in rbFGF-induced reinitiation of DNA synthesis. Moreover, we have found no evidence for diacylglycerol accumulation in response to rbFGF by 3T3 cells. In previous studies, we observed that rbFGF caused a moderate and slow accumulation of total inositol phosphates. This effect was significant only after a 60 min incubation. It is our contention that rbFGF, in our culture system, does not exert a direct effect on phosphoinositide metabolism.
Virdee
K
K
Department of Human Metabolism and Clinical Biochemistry, University of Sheffield Medical School, UK.
Brown
B L
BL
Dobson
P R
PR
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D016475:3T3 Cells; D000818:Animals; D004261:DNA Replication / Q000187:drug effects; D004075:Diglycerides / Q000096:biosynthesis*; D015536:Down-Regulation; D004789:Enzyme Activation; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D007546:Isoquinolines / Q000494:pharmacology; D051379:Mice; D008934:Mitogens / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004075:Diglycerides; D007546:Isoquinolines; D008934:Mitogens; D010879:Piperazines; D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2; C035561:diarachidonyl diglyceride; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate