title: ArPIKfyve-PIKfyve interaction and role in insulin-regulated GLUT4 translocation and glucose transport in 3T3-L1 adipocytes.
abstract: Insulin activates glucose transport by promoting translocation of the insulin-sensitive fat/muscle-specific glucose transporter GLUT4 from an intracellular storage compartment to the cell surface. Here we report that an optimal insulin effect on glucose uptake in 3T3-L1 adipocytes is dependent upon expression of both PIKfyve, the sole enzyme for PtdIns 3,5-P(2) biosynthesis, and the PIKfyve activator, ArPIKfyve. Small-interfering RNAs that selectively ablated PIKfyve or ArPIKfyve in this cell type depleted the PtdIns 3,5-P(2) pool and reduced insulin-activated glucose uptake to a comparable degree. Combined loss of PIKfyve and ArPIKfyve caused further PtdIns 3,5-P(2) ablation that correlated with greater attenuation in insulin responsiveness. Loss of PIKfyve-ArPIKfyve reduced insulin-stimulated Akt phosphorylation and the cell surface accumulation of GLUT4 or IRAP, but not GLUT1-containing vesicles without affecting overall expression of these proteins. ArPIKfyve and PIKfyve were found to physically associate in 3T3-L1 adipocytes and this was insulin independent. In vitro labeling of membranes isolated from basal or insulin-stimulated 3T3-L1 adipocytes documented substantial insulin-dependent increases of PtdIns 3,5-P(2) production on intracellular membranes. Together, the data demonstrate for the first time a physical association between functionally related PIKfyve and ArPIKfyve in 3T3-L1 adipocytes and indicate that the novel ArPIKfyve-PIKfyve-PtdIns 3,5-P(2) pathway is physiologically linked to insulin-activated GLUT4 translocation and glucose transport.
authors.affiliation: Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Ognian C
authors.initials: OC
authors.lastname: Ikonomov
authors.forename: Diego
authors.initials: D
authors.lastname: Sbrissa
authors.forename: Rajeswari
authors.initials: R
authors.lastname: Dondapati
authors.forename: Assia
authors.initials: A
authors.lastname: Shisheva
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000096:biosynthesis*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D021381:Protein Transport; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D005947:Glucose; D051275:Glucose Transporter Type 4; D007328:Insulin; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; C525133:Vac14 protein, mouse; C106336:phosphatidylinositol 3,5-diphosphate; C116930:Pikfyve protein, mouse