Stumpo D J, Stewart T N, Gilman M Z, Blackshear P J
Howard Hughes Medical Institute Laboratories, Durham, North Carolina 27710.
J Biol Chem. 1988 Feb 5;263(4):1611-4.
We evaluated the mechanism of insulin and phorbol ester induction of the proto-oncogene c-fos in Chinese hamster ovary fibroblasts stably transformed with high levels of genes expressing normal or truncated human insulin receptors. Both insulin and the tumor-promoting phorbol ester phorbol 12-myristate 13-acetate (PMA) induced c-fos mRNA accumulation in cells expressing high numbers of normal human insulin receptors; PMA but not insulin was effective in the cells expressing the mutant receptor. Transient expression studies with plasmid constructions containing c-fos 5'-flanking sequences ligated to the bacterial chloramphenicol acetyltransferase gene indicated that sequences corresponding to the serum response element were required for induction of c-fos transcription by both insulin and PMA. The insulin-sensitive cells contained a nuclear factor, presumably a protein, which bound specifically to this sequence of the c-fos gene; the apparent affinity of this factor to the normal serum response element was not affected by prior treatment of the cells with insulin or PMA. This c-fos binding factor may prove to be important in the regulation of c-fos expression by insulin and activators of protein kinase C.
我们评估了胰岛素和佛波酯在中国仓鼠卵巢成纤维细胞中诱导原癌基因c-fos的机制，这些细胞通过高水平表达正常或截短的人胰岛素受体基因而被稳定转化。胰岛素和促肿瘤佛波酯佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）均可诱导大量表达正常人胰岛素受体的细胞中c-fos mRNA的积累；PMA而非胰岛素在表达突变受体的细胞中有效。用含有与细菌氯霉素乙酰转移酶基因连接的c-fos 5'侧翼序列的质粒构建体进行的瞬时表达研究表明，胰岛素和PMA诱导c-fos转录均需要与血清反应元件相对应的序列。胰岛素敏感细胞含有一种核因子，推测为一种蛋白质，它能特异性结合c-fos基因的这一序列；该因子与正常血清反应元件的表观亲和力不受细胞预先用胰岛素或PMA处理的影响。这种c-fos结合因子可能在胰岛素和蛋白激酶C激活剂对c-fos表达的调节中起重要作用。
