Comparative effects of CTPγS and insulin on the activation of Rho, phosphatidylinositol 3-kinase, and protein kinase N in rat adipocytes -: Relationship to glucose transport
Comparative effects of CTPγS and insulin on the activation of Rho, phosphatidylinositol 3-kinase, and protein kinase N in rat adipocytes -: Relationship to glucose transport
复制标题
DOI：
10.1074/jbc.273.13.7470
复制
发表时间：
1998-03-27
影响因子：
4.8
通讯作者：
Farese, R
中科院分区：
文献类型：
--
作者：
Standaert, M;Bandyopadhyay, G;Farese, R
用鸟苷 5'-3-O-(硫代)三磷酸 (GTP gamma S) 电穿孔大鼠脂肪细胞，引起葡萄糖转运和 GLUT4 易位的胰岛素样显着增加。与胰岛素一样，GTP gamma S 激活大鼠脂肪细胞中的膜磷脂酰肌醇 (PI) 3-激酶，但与胰岛素不同的是，这种激活被肉毒杆菌 C3 转移酶阻断，表明需要小 G 蛋白 RhoA。还表明，在 GTP gamma S 作用期间，Rho 可能在 PI 3 激酶上游发挥作用，3T3/L1 脂肪细胞中 Rho 的稳定过表达引起膜 PI 3 激酶活性的增加。与胰岛素治疗一样，C3 转移酶、渥曼青霉素、LY294002 和 RO 31-8220 阻断 GTP gamma S 对大鼠脂肪细胞中葡萄糖转运的刺激；因此，GTP gamma S 以及胰岛素对葡萄糖转运的激活似乎需要 Rho、PI S 激酶和另一种下游激酶，例如 Rho、PI S 激酶和另一种下游激酶。蛋白激酶 C-zeta (PKC-zeta) 和/或蛋白激酶 N (PKN)。胰岛素同时激活 PKN 和 PKC-zeta，而 GTP gamma S 激活 PKN，但不激活 PKC-zeta。在 3T3/L1 细胞的转染研究中，野生型 Rho 和 PKN 的稳定表达激活葡萄糖转运，而显性失活形式的 Rho 和 PKN 抑制胰岛素刺激的葡萄糖转运。在大鼠脂肪细胞的转染研究中，野生型和组成型 Rho 和野生型 PI(N 的瞬时表达引起血凝素 (HA) 标记的 GLUT4 向质膜易位的增加；相反，Rho 和 PKN 的显性失活形式的瞬时表达抑制胰岛素和 GTP gamma S 对 HA-GLUT4 易位的影响。我们的研究结果表明，(a) GTP gamma S 和胰岛素激活 Rho、PI S-激酶和 PKN，尽管机制不同；(b) 这些信号物质中的每一种似乎都是葡萄糖转运增加所必需的，并且可能有助于增加胰岛素的转运；(c) PKC-zeta 可能有助于胰岛素作用期间葡萄糖转运的增加，但不会增加 GTP gamma S 的作用。
Electroporation of rat adipocytes with guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) elicited sizable insulinlike increases in glucose transport and GLUT4 translocation. Like insulin, GTP gamma S activated membrane phosphatidylinositol (PI) 3-kinase in rat adipocytes, but, unlike insulin, this activation was blocked by Clostridium botulinum C3 transferase, suggesting a requirement for the small G-protein, RhoA. Also suggesting that Rho may operate upstream of PI 3-kinase during GTP gamma S action, the stable overexpression of Rho in 3T3/L1 adipocytes provoked increases in membrane PI 3-kinase activity. As with insulin treatment, GTP gamma S stimulation of glucose transport in rat adipocytes was blocked by C3 transferase, wortmannin, LY294002, and RO 31-8220; accordingly, the activation of glucose transport by GTP gamma S, as well as insulin, appeared to require Rho, PI S-kinase, and another downstream kinase, e.g. protein kinase C-zeta (PKC-zeta) and/or protein kinase N (PKN). Whereas insulin activated both PKN and PKC-zeta, GTP gamma S activated PKN but not PKC-zeta. In transfection studies in 3T3/L1 cells, stable expression of wild-type Rho and PKN activated glucose transport, and dominant-negative forms of Rho and PKN inhibited insulin stimulated glucose transport. In transfection studies in rat adipocytes, transient expression of wild-type and constitutive Rho and wildtype PI(N provoked increases in the translocation of hemagglutinin (HA)-tagged GLUT4 to the plasma membrane; in contrast, transient expression of dominant-negative forms of Rho and PKN inhibited the effects of both insulin and GTP gamma S on HA-GLUT4 translocation. Our findings suggest that (a) GTP gamma S and insulin activate Rho, PI S-kinase, and PKN, albeit by different mechanisms; (b) each of these signaling substances appears to be required for, and may contribute to, increases in glucose transport; and (c) PKC-zeta may contribute to increases in glucose transport during insulin, but not GTP gamma S, action.