Presta M, Maier J A, Ragnotti G
Department of Biomedical Sciences and Biotechnologies, School of Medicine, University of Brescia, Italy.
J Cell Biol. 1989 Oct;109(4 Pt 1):1877-84. doi: 10.1083/jcb.109.4.1877.
Basic fibroblast growth factor (bFGF) induces cell proliferation and plasminogen activator (PA) activity in transformed fetal bovine aortic endothelial (FBAE) GM 7373 cells. A similar response is observed after treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA). In these cells, bFGF and TPA cause activation of protein kinase C (PKC), as demonstrated by the induction of the phosphorylation of an 87-kD PKC substrate in intact cells and by the increase in membrane-associated PKC activity. Activation of PKC by bFGF or TPA is inhibited in cells made PKC-deficient by pretreatment with high concentrations of TPA. The mitogenic activity of bFGF or of TPA is completely inhibited in PKC-deficient cells or in naive cells treated with the PKC inhibitor H-7. However, these cells proliferate in response to serum, epidermal growth factor, and dibutyryl cyclic AMP. Similar results are obtained in normal FBAE AG 7680 cells. These data indicate that activation of PKC is responsible for the mitogenic activity of bFGF in FBAE cells. On the contrary, the PA-inducing activity of bFGF is unaffected by down-regulation of PKC or by treatment with the PKC inhibitor H-7 in both transformed GM 7373 and normal AG 7680 cells. bFGF induces a rapid 45Ca influx in naive and in PKC-deprived GM 7373 cells. In these cells, addition of EGTA to the incubation medium prevents both the 45Ca influx and the increase in PA activity induced by bFGF, without affecting its mitogenic activity. Even though the involvement of PKC in the increase of cell-associated PA activity induced by bFGF can not be completely dismissed, the present results suggest a role of calcium entry in the modulation of the PA-inducing activity of bFGF.
碱性成纤维细胞生长因子（bFGF）可诱导转化的胎牛主动脉内皮（FBAE）GM 7373细胞增殖并激活纤溶酶原激活物（PA）活性。用12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯（TPA）处理后也观察到类似反应。在这些细胞中，bFGF和TPA可导致蛋白激酶C（PKC）激活，这在完整细胞中87-kD PKC底物磷酸化的诱导以及膜相关PKC活性的增加中得到证实。通过用高浓度TPA预处理使PKC缺乏的细胞中，bFGF或TPA对PKC的激活受到抑制。在PKC缺乏的细胞或用PKC抑制剂H - 7处理的未处理细胞中，bFGF或TPA的促有丝分裂活性被完全抑制。然而，这些细胞可对血清、表皮生长因子和二丁酰环磷腺苷作出增殖反应。在正常FBAE AG 7680细胞中也获得了类似结果。这些数据表明PKC的激活是bFGF在FBAE细胞中促有丝分裂活性的原因。相反，在转化的GM 7373细胞和正常AG 7680细胞中，bFGF的PA诱导活性不受PKC下调或PKC抑制剂H - 7处理的影响。bFGF可诱导未处理的和PKC缺失的GM 7373细胞中快速的45Ca内流。在这些细胞中，向孵育培养基中添加乙二醇双乙醚四乙酸（EGTA）可阻止45Ca内流以及bFGF诱导的PA活性增加，而不影响其促有丝分裂活性。尽管不能完全排除PKC参与bFGF诱导的细胞相关PA活性增加，但目前的结果表明钙内流在调节bFGF的PA诱导活性中起作用。
