title: Full intracellular retention of GLUT4 requires AS160 Rab GTPase activating protein.
abstract: Insulin controls glucose flux into muscle and fat by regulating the trafficking of GLUT4 between the interior and surface of cells. Here, we show that the AS160 Rab GTPase activating protein (GAP) is a negative regulator of basal GLUT4 exocytosis. AS160 knockdown resulted in a partial redistribution of GLUT4 from intracellular compartments to the plasma membrane, a concomitant increase in basal glucose uptake, and a 3-fold increase in basal GLUT4 exocytosis. Reexpression of wild-type AS160 restored normal GLUT4 behavior to the knockdown adipocytes, whereas reexpression of a GAP domain mutant did not revert the phenotype, providing the first direct evidence that AS160 GAP activity is required for basal GLUT4 retention. AS160 is the first protein identified that is specially required for basal GLUT4 retention. Our findings that AS160 knockdown only partially releases basal GLUT4 retention provides evidence that insulin signals to GLUT4 exocytosis by both AS160-dependent and -independent mechanisms.
authors.affiliation: Department of Biochemistry, Weill-Cornell Medical School, New York, New York 10021, USA.
authors.forename: Lorena
authors.initials: L
authors.lastname: Eguez
authors.forename: Adrian
authors.initials: A
authors.lastname: Lee
authors.forename: Jose A
authors.initials: JA
authors.lastname: Chavez
authors.forename: Cristinel P
authors.initials: CP
authors.lastname: Miinea
authors.forename: Susan
authors.initials: S
authors.lastname: Kane
authors.forename: Gustav E
authors.initials: GE
authors.lastname: Lienhard
authors.forename: Timothy E
authors.initials: TE
authors.lastname: McGraw
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D011992:Endosomes / Q000378:metabolism; D005089:Exocytosis; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D053590:Interleukin 1 Receptor Antagonist Protein; D051379:Mice; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011990:Receptors, Transferrin / Q000378:metabolism; D012795:Sialoglycoproteins / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection
chemical_list: D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; C507763:IL1RN protein, human; C507764:Il1rn protein, mouse; D007328:Insulin; D053590:Interleukin 1 Receptor Antagonist Protein; D034741:RNA, Small Interfering; D011990:Receptors, Transferrin; C495692:SLC2A4 protein, human; D012795:Sialoglycoproteins; C495693:Slc2a4 protein, mouse; D005947:Glucose