Protein kinase B phosphorylation of PIKfyve regulates the trafficking of GLUT4 vesicles
Protein kinase B phosphorylation of PIKfyve regulates the trafficking of GLUT4 vesicles
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DOI：
10.1242/jcs.01517
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发表时间：
2004-12-01
影响因子：
4
通讯作者：
Tavaré, JM
中科院分区：
文献类型：
--
作者：
Berwick, DC;Dell, GC;Tavaré, JM
胰岛素刺激的葡萄糖摄取涉及葡萄糖转运蛋白4亚型（GLUT 4）从细胞内位置募集到脂肪和肌肉细胞的质膜。尽管PI 3-激酶/蛋白激酶B（PK B）通路的激活是胰岛素这种作用的核心，但所涉及的PK B的关键底物需要鉴定。在这里，我们报告，丝氨酸318的FYVE域含有PtdIns（3）P5-激酶（PIKfyve）是一种新的底物PKB，并表明磷酸化刺激PtdIns（3）P5-激酶的酶的活性。我们还证明，PIKfyve是磷酸化的丝氨酸318在完整的细胞响应胰岛素，在PI 3激酶依赖性的方式，PIKfyve共定位与胰岛素调节的氨基肽酶（IRAP）/GLUT 4囊泡的高度能动的亚群。最后，我们证明了PIKfyve[S318 A]突变体在3 T3-L1脂肪细胞中的过表达增强了胰岛素刺激的IRAP/GLUT 4囊泡向质膜的易位，这表明PIKfyve的PKB依赖性磷酸化在胰岛素调节的IRAP/GLUT 4运输中的作用。PIKfyve通过PKB的磷酸化和激活提供了一种新的信号传导模式，其可以通过蛋白激酶级联将质膜定位的PtdIns（3，4，5）P-3信号与调节的PtdIns（3，5）P-2产生联系起来，从而控制其他膜货物的运输。
Insulin-stimulated glucose uptake involves the recruitment of the glucose transporter 4 isoform (GLUT4) from an intracellular location to the plasma membrane of fat and muscle cells. Although the activation of the PI3-kinase/protein kinase B (PKB) pathway is central to this effect of insulin, the key substrates for PKB that are involved require identification. Here we report that serine318 on the FYVE domain-containing PtdIns(3)P 5-kinase (PIKfyve) is a novel substrate for PKB, and show that phosphorylation stimulates the PtdIns(3)P 5-kinase activity of the enzyme. We also demonstrate that PIKfyve is phosphorylated on serine318 in intact cells in response to insulin, in a PI3-kinase-dependent manner, and that PIKfyve colocalises with a highly motile subpopulation of insulin-regulated aminopeptidase (IRAP)/GLUT4 vesicles. Finally, we demonstrate that overexpression of a PIKfyve[S318A] mutant in 3T3-L1 adipocytes enhances insulin-stimulated IRAP/GLUT4 vesicle translocation to the plasma membrane suggesting a role for PKB-dependent phosphorylation of PIKfyve in insulin-regulated IRAP/GLUT4 trafficking. The phosphorylation and activation of PIKfyve by PKB provides a novel signalling paradigm that may link plasma membrane-localised PtdIns(3,4,5)P-3 signals via a protein kinase cascade to regulated PtdIns(3,5)P-2 production, and thereby to the control of trafficking of other membrane cargos.