Calmodulin antagonists inhibit insulin-stimulated GLUT4 (glucose transporter 4) translocation by preventing the formation of phosphatidylinositol 3,4,5-trisphosphate in 3T3L1 adipocytes.
Calmodulin antagonists inhibit insulin-stimulated GLUT4 (glucose transporter 4) translocation by preventing the formation of phosphatidylinositol 3,4,5-trisphosphate in 3T3L1 adipocytes.
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DOI：
10.1210/mend.14.2.0425
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发表时间：
2000-02
影响因子：
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通讯作者：
Chunmei Yang;Robert T. Watson;J. S. Elmendorf;David B. Sacks;J. Pessin
中科院分区：
文献类型：
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作者：
Chunmei Yang;Robert T. Watson;J. S. Elmendorf;David B. Sacks;J. Pessin
此前已有报道称，钙调蛋白在胰岛素刺激葡萄糖转运中发挥调节作用。为了检验这一观察结果的基础，我们检查了一组钙调蛋白拮抗剂的作用，这些拮抗剂显示出对胰岛素刺激的葡萄糖转运蛋白 4 (GLUT4) 的特异性抑制，但对 3T3L1 脂肪细胞中胰岛素或血小板衍生生长因子 (PDGF) 刺激的 GLUT1 易位没有特异性抑制。这些治疗对胰岛素受体自身磷酸化或胰岛素受体底物 1 (IRS1) 的酪氨酸磷酸化没有影响。此外，IRS1 或磷酸酪氨酸抗体免疫沉淀磷脂酰肌醇 (PI) 3-激酶活性未受影响。尽管胰岛素和PDGF显着刺激PI 3-激酶活性，但蛋白激酶B的激活几乎完全受到抑制。使用 Grp1 pleckstrin 同源 (PH) 结构域与增强型绿色荧光蛋白的融合蛋白，我们发现钙调蛋白拮抗剂可阻止体内胰岛素刺激磷脂酰肌醇 3,4,5-三磷酸 [PI(3,4,5)P3] 形成。类似地，尽管PDGF刺激在体外免疫沉淀测定中增加了PI 3激酶活性，但在体内也没有显着形成PI(3,4,5)P3。这些数据表明，钙调蛋白拮抗剂通过抑制 PI(3,4,5)P3 的体内产生来防止胰岛素刺激的 GLUT4 易位，而不直接影响 IRS1 或磷酸酪氨酸相关的 PI 3 激酶活性。这种现象与 PDGF 刺激 3T3L1 脂肪细胞时观察到的现象相似。
It has been previously reported that calmodulin plays a regulatory role in the insulin stimulation of glucose transport. To examine the basis for this observation, we examined the effect of a panel of calmodulin antagonists that demonstrated a specific inhibition of insulin-stimulated glucose transporter 4 (GLUT4) but not insulin- or platelet-derived growth factor (PDGF)-stimulated GLUT1 translocation in 3T3L1 adipocytes. These treatments had no effect on insulin receptor autophosphorylation or tyrosine phosphorylation of insulin receptor substrate 1 (IRS1). Furthermore, IRS1 or phosphotyrosine antibody immunoprecipitation of phosphatidylinositol (PI) 3-kinase activity was not affected. Despite the marked insulin and PDGF stimulation of PI 3-kinase activity, there was a near complete inhibition of protein kinase B activation. Using a fusion protein of the Grp1 pleckstrin homology (PH) domain with the enhanced green fluorescent protein, we found that the calmodulin antagonists prevented the insulin stimulation of phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] formation in vivo. Similarly, although PDGF stimulation increased PI 3-kinase activity in in vitro immunoprecipitation assays, there was also no significant formation of PI(3,4,5)P3 in vivo. These data demonstrate that calmodulin antagonists prevent insulin-stimulated GLUT4 translocation by inhibiting the in vivo production of PI(3,4,5)P3 without directly affecting IRS1- or phosphotyrosine-associated PI 3-kinase activity. This phenomenon is similar to that observed for the PDGF stimulation of 3T3L1 adipocytes.