Vegesna R V, Wu H L, Mong S, Crooke S T
Department of Molecular Pharmacology, Smith Kline & French Laboratories, Philadelphia, Pennsylvania 19101.
Mol Pharmacol. 1988 May;33(5):537-42.
The aim of the present study was to investigate the effects of staurosporine on phorbol-myristate acetate (PMA)-induced activation of protein kinase C (PKC) and the desensitization of leukotriene D4 (LTD4)-stimulated Ca2+ mobilization in rat basophilic leukemia (RBL-1) cells. Staurosporine, one of the most potent PKC inhibitors known to date, markedly inhibited partially purified PKC from RBL-1 cells with an IC50 of 3 nM. Exposure of RBL-1 cells to PMA resulted in inhibition of LTD4-stimulated Ca2+ mobilization. However, prior treatment of the cells with staurosporine completely prevented PMA-induced desensitization of LTD4-stimulated Ca2+ mobilization. This reversal of Ca2+ desensitization by staurosporine was dose dependent with an IC50 of 0.1 microM. Treatment of RBL-1 cells with PMA resulted in translocation and activation of PKC from the cytosol to the membrane fraction. Pretreatment of RBL-1 cells with staurosporine inhibited the PMA-induced activation of PKC in the membrane fraction. The inhibition of PKC activity by staurosporine was time and dose dependent with an IC50 of 0.9 microM. These results show that PMA-induced heterologous desensitization is mediated by PKC and staurosporine prevented this process by directly inhibiting PKC in intact RBL-1 cells.
本研究的目的是探讨星形孢菌素对佛波醇-肉豆蔻酸酯乙酸酯（PMA）诱导的蛋白激酶C（PKC）激活以及对白三烯D4（LTD4）刺激的大鼠嗜碱性白血病（RBL-1）细胞Ca2+动员脱敏的影响。星形孢菌素是迄今为止已知的最有效的PKC抑制剂之一，它能显著抑制来自RBL-1细胞的部分纯化的PKC，IC50为3 nM。将RBL-1细胞暴露于PMA会导致LTD4刺激的Ca2+动员受到抑制。然而，用星形孢菌素预先处理细胞可完全防止PMA诱导的LTD4刺激的Ca2+动员脱敏。星形孢菌素对Ca2+脱敏的这种逆转呈剂量依赖性，IC50为0.1 microM。用PMA处理RBL-1细胞会导致PKC从胞质溶胶转运至膜部分并被激活。用星形孢菌素预先处理RBL-1细胞可抑制PMA诱导的膜部分PKC激活。星形孢菌素对PKC活性的抑制具有时间和剂量依赖性，IC50为0.9 microM。这些结果表明，PMA诱导的异源脱敏由PKC介导，而星形孢菌素通过直接抑制完整RBL-1细胞中的PKC来阻止这一过程。
