Caro J F, Jenquin M, Long S
Department of Medicine, School of Medicine, East Carolina University, Greenville, NC 27858-4354.
Mol Cell Biochem. 1992 Feb 12;109(2):115-8. doi: 10.1007/BF00229764.
We investigated the effect of phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator on insulin receptors and insulin action in freshly isolated and primary cultures of rat hepatocytes. PMA (1 x 10(-7) M) did not alter insulin receptor numbers or affinity either acutely or chronically but within 60 minute inactivated insulin stimulated tyrosine kinase of the insulin receptor. PKC activation inhibited insulin (1 x 10(-7) M) stimulation of glycogen and lipid synthesis with a decrease or no change in basal glycogenesis and lipogenesis respectively. However, PKC activation did not alter insulin stimulated or basal amino acid transport even though PKC activation inhibited insulin stimulation of the insulin receptor tyrosine kinase. Thus, within one tissue, PKC activation has differential effect on insulin action depending on which pathway is examined. Furthermore, insulin stimulation of the insulin receptor tyrosine kinase may not be a necessary step for all insulin signaling pathways.
我们研究了佛波醇12 -肉豆蔻酸酯13 -乙酸酯（PMA），一种蛋白激酶C（PKC）激活剂，对新鲜分离的大鼠肝细胞及原代培养肝细胞中胰岛素受体和胰岛素作用的影响。PMA（1×10⁻⁷M）无论是急性还是慢性处理，均未改变胰岛素受体的数量或亲和力，但在60分钟内可使胰岛素刺激的胰岛素受体酪氨酸激酶失活。PKC激活抑制胰岛素（1×10⁻⁷M）对糖原和脂质合成的刺激作用，同时基础糖原生成和脂肪生成分别减少或无变化。然而，尽管PKC激活抑制了胰岛素对胰岛素受体酪氨酸激酶的刺激，但并未改变胰岛素刺激的或基础的氨基酸转运。因此，在同一组织内，PKC激活对胰岛素作用的影响因所检测的途径而异。此外，胰岛素对胰岛素受体酪氨酸激酶的刺激可能并非所有胰岛素信号通路的必要步骤。
