title: The Rab GTPase-activating protein AS160 as a common regulator of insulin- and Galphaq-mediated intracellular GLUT4 vesicle distribution.
abstract: Akt substrate of 160kDa (AS160) is a Rab GTPase activating protein (GAP) and was recently identified as a component of the insulin signaling pathway of glucose transporter type 4 (GLUT4) translocation. We and others, previously reported that the activation of Galphaq protein-coupled receptors (GalphaqPCRs) also stimulated GLUT4 translocation and glucose uptake in several cell lines. Here, we report that the activation of GalphaqPCRs also promoted phosphorylation of AS160 by the 5'-AMP activated protein kinase (AMPK). The suppression of AS160 phosphorylation by the siRNA mediated AMPKalpha1 subunit knockdown promoted GLUT4 vesicle retention in intracellular compartments. This suppression did not affect the ratio of non-induced cell surface GLUT4 to Galphaq-induced it. Rat 3Y1 cells lacking AS160 did not show insulin-induced GLUT4 translocation. The cells stably expressing GLUT4 revealed GLUT4 vesicles that were mainly localized in the perinuclear region and less frequently on the cell surface. After expression of exogenous AS160, GLUT4 on the cell surface decreased and GLUT4 vesicles were redistributed throughout the cytoplasm. Although PMA-induced or sodium fluoride-induced GLUT4 translocation was significantly increased in these cells, insulin did not affect GLUT4 translocation. These results suggest that AS160 is a common regulator of insulin- and GalphaqPCR activation-mediated GLUT4 distribution in the cells.
authors.affiliation: Division of Molecular Genetics, Institute for Enzyme Research, The University of Tokushima, Kuramotocho, Tokushima, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yuasa
authors.forename: Keiji
authors.initials: K
authors.lastname: Uchiyama
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ogura
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kimura
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Teshigawara
authors.forename: Toshio
authors.initials: T
authors.lastname: Hosaka
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Obata
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sano
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kishi
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Ebina
mesh_terms: D041721:3T3-L1 Cells / Q000378:metabolism; D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism* / Q000502:physiology; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000502:physiology; D051379:Mice; D051381:Rats
chemical_list: D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; D007328:Insulin; C533101:TBC1D4 protein, rat; D055372:AMP-Activated Protein Kinases; D043802:GTP-Binding Protein alpha Subunits, Gq-G11