Kim S J
Department of Pharmacology, School of Dentistry Kyung-Hee University, Seoul, Korea.
Biochem Mol Biol Int. 1998 Sep;46(1):187-96. doi: 10.1080/15216549800203692.
Insulin action on nuclear PI3-Kinase and IRS-1 was explored in HepG2 cells. Following insulin treatment, the cells were subjected to subcellular fractionation. Western blot analyses were carried out to identify IRS-1 and PI3-Kinase in the nuclear and postnuclear preparations. IRS-1 protein was identified in the nucleus under basal condition. Insulin had no effect in the content of nuclear IRS-1. In contrast, PI3-Kinase was not detected under basal condition. However, insulin treatment for 1 to 10 min caused significant increase of PI3-Kinase in the nucleus while it induced corresponding decrease of PI3-Kinase in cytoplasm. Strikingly, Insulin stimulated the association of IRS-1 and PI3-Kinase in the nucleus in a similar kinetics with the nuclear translocation of PI3-Kinase. These results suggest that insulin induces nuclear translocation of PI3-Kinase and the translocated PI3-Kinase associates with nuclear IRS-1. The association of IRS-1 and PI3-Kinase in the nucleus in response to insulin may play important roles in nuclear insulin actions.
在HepG2细胞中研究了胰岛素对细胞核PI3激酶和胰岛素受体底物1（IRS-1）的作用。胰岛素处理后，对细胞进行亚细胞分级分离。进行蛋白质免疫印迹分析以鉴定细胞核和细胞核后制剂中的IRS-1和PI3激酶。在基础条件下在细胞核中鉴定出IRS-1蛋白。胰岛素对细胞核IRS-1的含量没有影响。相反，在基础条件下未检测到PI3激酶。然而，胰岛素处理1至10分钟导致细胞核中PI3激酶显著增加，同时诱导细胞质中PI3激酶相应减少。引人注目的是，胰岛素以与PI3激酶核转位相似的动力学刺激细胞核中IRS-1和PI3激酶的结合。这些结果表明，胰岛素诱导PI3激酶的核转位，并且转位的PI3激酶与细胞核IRS-1结合。响应胰岛素，细胞核中IRS-1和PI3激酶的结合可能在细胞核胰岛素作用中起重要作用。
