Fassio A, Cofano F, Cavallo G, Landolfo S
Biochem Biophys Res Commun. 1987 Apr 14;144(1):337-44. doi: 10.1016/s0006-291x(87)80515-6.
Treatment of mouse EL-4 cells with intracellular activators of protein kinase C, namely 4-phorbol 12-myristate 13-acetate (PMA) and diacylglycerol, resulted in 90% reduction in cell surface interferon-gamma (IFN-gamma) receptors as judged by iodinated-IFN-gamma binding. This did not seem to be due to a decreased in the receptor affinity, since that of the remaining surface receptors appeared to be significantly increased as shown in Scatchard plot analysis. Kinetics experiments revealed that a PMA treatment as short as 15 min was sufficient to induce a decrease of 30% of IFN-gamma receptors, whereas the highest levels of down-regulation were observed after 60-90 min. Treatment of EL-4 cells with calcium ionophore, A23187, although ineffective by itself, dramatically increased the ability of suboptimal PMA concentrations to mediate IFN-gamma receptor down-regulation. Finally, specificity studies revealed that PMA is particularly effective in decreasing the binding of IFN-gamma to T-lymphocytes. Altogether these results suggest a possible involvement of protein kinase C in the regulation of IFN-gamma receptor expression.
用蛋白激酶C的细胞内激活剂，即4-佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）和二酰基甘油处理小鼠EL-4细胞，通过碘化干扰素-γ（IFN-γ）结合判断，细胞表面IFN-γ受体减少了90%。这似乎不是由于受体亲和力降低，因为在Scatchard图分析中显示，剩余表面受体的亲和力似乎显著增加。动力学实验表明，短至15分钟的PMA处理足以诱导IFN-γ受体减少30%，而在60-90分钟后观察到最高水平的下调。用钙离子载体A23187处理EL-4细胞，尽管其本身无效，但显著增强了次优PMA浓度介导IFN-γ受体下调的能力。最后，特异性研究表明，PMA在降低IFN-γ与T淋巴细胞的结合方面特别有效。总之，这些结果表明蛋白激酶C可能参与了IFN-γ受体表达的调节。
