Shafit-Zagardo B, Kume-Iwaki A, Goldman J E
Department of Pathology, Albert Einstein College of Medicine, Bronx, New York 10461.
Glia. 1988;1(5):346-54. doi: 10.1002/glia.440010507.
Glial fibrillary acidic protein (GFAP) mRNA and protein levels in rat astrocyte cultures and in the human astrocytoma line U-373MG were examined in order to determine the effects of agents that regulate cAMP-dependent kinase and protein kinase C. Treatment of cells with dibutyryl cAMP or forskolin and 3-isobutyl-1-methylxanthine increased steady-state GFAP mRNA levels. Short-term treatment of cells with phorbol-12-myristate-13-acetate (PMA) increased GFAP mRNA levels, but prolonged treatment of cells with PMA or 1-oleoyl-2-acetyl-rac-glycerol produced a dramatic decrease in GFAP mRNA; 4-beta-phorbol had no effect. Thus, both cAMP-dependent kinase and protein kinase C may exert regulatory roles in determining GFAP mRNA levels. Nuclear run-off studies showed no change in GFAP mRNA synthesis after cAMP or PMA treatment, suggesting post-transcriptional mechanisms. Western blot analysis revealed that the effect of PMA on U-373MG cells shows specificity in that GFA protein levels decline, while those of other major cytoskeletal proteins were unaltered.
为了确定调节环磷酸腺苷（cAMP）依赖性激酶和蛋白激酶C的药物的作用，研究了大鼠星形胶质细胞培养物和人星形细胞瘤细胞系U-373MG中胶质纤维酸性蛋白（GFAP）的mRNA和蛋白质水平。用二丁酰cAMP或福斯可林以及3-异丁基-1-甲基黄嘌呤处理细胞可增加GFAP mRNA的稳态水平。用佛波醇-12-肉豆蔻酸酯-13-乙酸酯（PMA）短期处理细胞可增加GFAP mRNA水平，但用PMA或1-油酰基-2-乙酰基-rac-甘油长期处理细胞会导致GFAP mRNA显著下降；4-β-佛波醇无作用。因此，cAMP依赖性激酶和蛋白激酶C在决定GFAP mRNA水平方面可能都发挥调节作用。细胞核转录实验表明，cAMP或PMA处理后GFAP mRNA合成没有变化，提示存在转录后机制。蛋白质免疫印迹分析显示，PMA对U-373MG细胞的作用具有特异性，即GFAP蛋白水平下降，而其他主要细胞骨架蛋白的水平未改变。
