Botana L M, Alfonso A, Botana M A, Vieytes M R, Louzao M C, Cabado A G
Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain.
Agents Actions. 1992 Sep;37(1-2):1-7. doi: 10.1007/BF01987883.
We have studied the effect of protein kinase C and protein kinase A activation, and phosphatase inhibition on two different stimuli with distinct mechanisms of action. The first stimulus is compound 48/80, and its action is mediated probably by a Gi-protein, while the other is sodium fluoride, which unspecifically activates G-proteins. We established a comparative study because the action of compound 48/80 is calcium-independent, while fluoride is strictly calcium-dependent. The activation of protein kinase C was attained with the phorbol esther 12-O-tetradecanoylphorbol-13-acetate, protein kinase A was activated by increasing cAMP levels with forskolin or rolipram, and the phosphatase activity was inhibited with okadaic acid (OA), which inhibits phosphatases type 1 and 2A. Our results show that OA enhances the response to fluoride and compound 48/80 in the absence of calcium, and we conclude that calcium has a negative feedback role on the cell response. Protein kinase A activation strongly inhibits the response to fluoride, and the results show a positive regulation of protein kinase C and a negative regulation of protein kinase A over fluoride response. As previously reported by other authors for the ionophore A23187, TPA notably potentiates the response to fluoride, which supports its possible modulatory role on extracellular calcium-dependent stimuli.
我们研究了蛋白激酶C和蛋白激酶A的激活以及磷酸酶抑制对两种具有不同作用机制的不同刺激的影响。第一种刺激是化合物48/80，其作用可能由Gi蛋白介导，而另一种是氟化钠，它非特异性地激活G蛋白。我们进行了一项比较研究，因为化合物48/80的作用不依赖钙，而氟化物则严格依赖钙。用佛波酯12-O-十四酰佛波醇-13-乙酸酯实现蛋白激酶C的激活，用福斯可林或咯利普兰提高cAMP水平来激活蛋白激酶A，并用抑制1型和2A型磷酸酶的冈田酸（OA）抑制磷酸酶活性。我们的结果表明，在无钙的情况下，OA增强了对氟化物和化合物48/80的反应，我们得出结论，钙对细胞反应具有负反馈作用。蛋白激酶A的激活强烈抑制对氟化物的反应，结果表明蛋白激酶C对氟化物反应具有正调节作用，而蛋白激酶A具有负调节作用。正如其他作者先前报道的离子载体A23187的情况一样，佛波酯显著增强了对氟化物的反应，这支持了其对细胞外钙依赖性刺激可能具有的调节作用。
