Singh K R, Taylor L K, Campbell X Z, Fields A P, Neet K E
Department of Biological Chemistry, UHS/Chicago Medical School, Illinois 60064.
Biochemistry. 1994 Jan 18;33(2):542-51. doi: 10.1021/bi00168a020.
Nerve growth factor (NGF) stimulates rat pheochromocytoma cells (PC12) to differentiate into a neuronal-like cell that exhibits neurite extensions. The role of protein kinase C in signal transduction has been examined in PC12 cells treated with phorbol 12-myristate 13-acetate (PMA) and bryostatin, a macrocyclic lactone that activates protein kinase C at both the nuclear and the plasma membranes [Hocevar, B. A., & Fields, A. P. (1991) J. Biol. Chem. 266, 28-33]. In contrast to PMA down-regulation [Reinhold, D. S., & Neet, K. E. (1989) J. Biol. Chem. 264, 3538-3544], chronic (24 h) treatment with bryostatin blocked the formation of neurites in response to NGF or basic fibroblast-derived growth factor stimulation, but, like PMA, bryostatin did not block the induction of c-fos or c-jun protooncogenes by NGF. Chronic bryostatin treatment down-regulated protein kinase C activity in the cytosolic, membrane, and nuclear fractions. Acute (60 min) bryostatin or NGF treatment activated cytosolic and nuclear protein kinase C activity, suggesting possible translocation to the nucleus. Bryostatin did not induce neurite outgrowth, either alone or in combination with PMA. Thus, the bryostatin-sensitive protein kinase C is distinct from PMA- or K252a-sensitive kinases previously described. The bryostatin-sensitive protein kinase C is necessary, but not sufficient, for neurite outgrowth and acts in the nucleus in a manner independent of c-fos and c-jun transcription.
神经生长因子（NGF）刺激大鼠嗜铬细胞瘤细胞（PC12）分化为具有神经突延伸的神经元样细胞。蛋白激酶C在信号转导中的作用已在经佛波酯12 - 肉豆蔻酸酯13 - 乙酸酯（PMA）和苔藓抑素处理的PC12细胞中进行了研究，苔藓抑素是一种大环内酯，可在核膜和质膜上激活蛋白激酶C[霍切瓦尔，B. A.，& 菲尔兹，A. P.（1991年）《生物化学杂志》266，28 - 33]。与PMA下调作用相反[莱因霍尔德，D. S.，& 尼特，K. E.（1989年）《生物化学杂志》264，3538 - 3544]，用苔藓抑素进行慢性（24小时）处理可阻断对NGF或碱性成纤维细胞衍生生长因子刺激的神经突形成，但与PMA一样，苔藓抑素并不阻断NGF对原癌基因c - fos或c - jun的诱导。慢性苔藓抑素处理下调了胞质、膜和核部分中的蛋白激酶C活性。急性（60分钟）苔藓抑素或NGF处理激活了胞质和核蛋白激酶C活性，提示可能发生了向核的转位。苔藓抑素单独或与PMA联合使用均未诱导神经突生长。因此，苔藓抑素敏感的蛋白激酶C与先前描述的PMA或K252a敏感激酶不同。苔藓抑素敏感的蛋白激酶C对于神经突生长是必需的，但并不充分，并且以独立于c - fos和c - jun转录的方式在细胞核中起作用。
