SIGNAL TRANSDUCTION FROM MEMBRANE TO CYTOPLASM - GROWTH-FACTORS AND MEMBRANE-BOUND ONCOGENE PRODUCTS INCREASE RAF-1 PHOSPHORYLATION AND ASSOCIATED PROTEIN-KINASE ACTIVITY
SIGNAL TRANSDUCTION FROM MEMBRANE TO CYTOPLASM - GROWTH-FACTORS AND MEMBRANE-BOUND ONCOGENE PRODUCTS INCREASE RAF-1 PHOSPHORYLATION AND ASSOCIATED PROTEIN-KINASE ACTIVITY
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DOI：
10.1073/pnas.85.23.8855
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发表时间：
1988-12-01
影响因子：
11.1
通讯作者：
ROBERTS, TM
中科院分区：
文献类型：
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作者：
MORRISON, DK;KAPLAN, DR;ROBERTS, TM
我们检测了原癌基因产物Raf-1(以前的c-raf)对小鼠3T3细胞的致癌转化或生长因子处理的反应中的磷酸化和丝氨酸/苏氨酸特异的激酶活性。V-fms、v-src、v-sis、多瘤病毒中型肿瘤抗原和Ha-ras编码的膜结合型癌基因产物的表达增加了Raf-1蛋白的表观分子量和磷酸化，而v-fos和c-myc编码的核癌基因和原癌基因产物的表达不增加。血小板衍生生长因子、酸性成纤维细胞生长因子、表皮生长因子和蛋白激酶C激活剂佛波酯12-肉豆蔻酸盐13-醋酸酯处理细胞后，凝胶迁移率和磷酸化的改变迅速发生，但不包括胰岛素。Raf-1蛋白的磷酸化主要发生在丝氨酸和苏氨酸残基上。然而，在被c-src转化或被血小板衍生生长因子刺激的细胞中，Raf-1分子的一个亚群在酪氨酸残基上被磷酸化。用v-src转化，或用血小板衍生生长因子或佛波醇12-肉豆蔻酸盐13-醋酸酯处理，激活免疫复合酶检测中测得的Raf-1相关丝氨酸/激酶活性。这些发现表明，在细胞膜上产生的增殖信号导致Raf-1蛋白的磷酸化和其丝氨酸/苏氨酸激酶活性的激活。因此，RAF-1的激活可能有助于将信号从细胞膜传递到细胞质，甚至可能传递到细胞核。
We have examined the phosphorylation and the serine/threonine-specific kinase acivity of the protooncogene product Raf-1 (formerly c-raf) in response to oncogenic transformation or growth-factor treatment of mouse 3T3 cells. Expression of the membrane-bound oncogene products encoded by v-fms, v-src, v-sis, polyoma virus middle-sized tumor antigen, and Ha-ras increased the apparent molecular weight and phosphorylation of the Raf-1 protein, while expression of the nuclear oncogene and protooncogene products encoded by v-fos and c-myc did not. Changes in electrophoretic mobility and phosphorylation occurred rapidly in response to treatment of cells with platelet-derived growth factor, acidic fibroblast growth factor, epidermal growth factor, and the protein kinase C activator phorbol 12-myristate 13-acetate, but not insulin. The phosphorylation of the Raf-1 protein occurred primarily on serine and threonine residues. However, a subpopulation of Raf-1 molecules was phosphorylated on tyrosine residues in cells transformed by c-src or stimulated with platelet-derived growth factor. Transformation by v-src, or treatment with platelet-derived growth factor or phorbol 12-myristate 13-acetate, activated the Raf-1-associated serine/kinase activity as measured in immune-complex kinase assays. These findings suggest that proliferative signals generated at the membrane results in the phosphorylation of the Raf-1 protein and the activation of its serine/threonine kinase activity. Raf-1 activation may thus serve to transduce signals from the membrane to the cytoplasm and perhaps on the nucleus.