Inhibitors of calcineurin block expression of cyclins A and E induced by fibroblast growth factor in Swiss 3T3 fibroblasts.
In Swiss 3T3 fibroblasts, growth factor-stimulated progression from G1 to S phase involves activation of the Ca2+/calmodulin-dependent serine/threonine-specific protein phosphatase 2B (calcineurin). Here we report that both cobalt and the calcium chelator EGTA, inhibitors of calcium uptake, as well as cyclosporin A and FK-506, specific inhibitors of calcineurin function, abolished fibroblast growth factor (FGF)-induced expression of cyclins A and E, but not cyclin D1. At 0.1 microM concentration cyclosporin A completely blocked FGF-induced expression of cyclins E and A and it inhibited FGF-stimulated DNA synthesis by 40%; full inhibition of DNA synthesis required 10 microM cyclosporin A. PD 98059, an inhibitor of mitogen-activated protein (MAP) kinase kinase, and hemicholinium-3, an inhibitor of FGF-induced MAP kinase activity, did not inhibit the stimulatory effect of FGF on the expression of cyclin E. On the other hand, the inhibitory effect of 0.1 microM cyclosporin A on FGF-stimulated DNA synthesis was additive with that of hemicholinium-3, suggesting that the two inhibitors acted by different mechanisms. The inhibitors of calcineurin and calcium uptake also completely blocked the stimulatory effects of lysophosphatidic acid on the expression of cyclins E and A, but not cyclin D1. The results suggest that FGF- or lysophosphatidic acid-induced transcription of cyclin A and cyclin E genes is mediated by calcineurin involving a MAP kinase-independent mechanism and that increased expression of cyclins A and E is required for the maximal stimulatory effects of these mitogens on DNA synthesis.
Tomono
M
M
Department of Biochemistry, Sakura Hospital, Toho University School of Medicine, Tokyo, Japan.
Toyoshima
K
K
Ito
M
M
Amano
H
H
Kiss
Z
Z
D016475:3T3 Cells; D000818:Animals; D065095:Calcineurin Inhibitors; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D019925:Cyclin A / Q000096:biosynthesis*; D019927:Cyclin E / Q000096:biosynthesis*; D016572:Cyclosporine / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005346:Fibroblast Growth Factors / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000494:pharmacology; D051379:Mice; D016559:Tacrolimus / Q000494:pharmacology
D065095:Calcineurin Inhibitors; D019925:Cyclin A; D019927:Cyclin E; D004791:Enzyme Inhibitors; D007166:Immunosuppressive Agents; D005346:Fibroblast Growth Factors; D016572:Cyclosporine; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D016559:Tacrolimus