title: Evidence for a role for ADP-ribosylation factor 6 in insulin-stimulated glucose transporter-4 (GLUT4) trafficking in 3T3-L1 adipocytes.
abstract: ADP-ribosylation factors (ARFs) play important roles in both constitutive and regulated membrane trafficking to the plasma membrane in other cells. Here we have examined their role in insulin-stimulated GLUT4 translocation in 3T3-L1 adipocytes. These cells express ARF5 and ARF6. ARF5 was identified in the soluble protein and intracellular membranes; in response to insulin some ARF5 was observed to re-locate to the plasma membrane. In contrast, ARF6 was predominantly localized to the plasma membrane and did not redistribute in response to insulin. We employed myristoylated peptides corresponding to the NH2 termini of ARF5 and ARF6 to investigate the function of these proteins. Myr-ARF6 peptide inhibited insulin-stimulated glucose transport and GLUT4 translocation by approximately 50% in permeabilized adipocytes. In contrast, myr-ARF1 and myr-ARF5 peptides were without effect. Myr-ARF5 peptide also inhibited the insulin stimulated increase in cell surface levels of GLUT1 and transferrin receptors. Myr-ARF6 peptide significantly decreased cell surface levels of these proteins in both basal and insulin-stimulated states, but did not inhibit the fold increase in response to insulin. These data suggest an important role for ARF6 in regulating cell surface levels of GLUT4 in adipocytes, and argue for a role for both ARF5 and ARF6 in the regulation of membrane trafficking to the plasma membrane.
authors.affiliation: Division of Biochemistry and Molecular Biology, Davidson Building, University of Glasgow, Glasgow G12 8QQ, Scotland.
authors.forename: C A
authors.initials: CA
authors.lastname: Millar
authors.forename: K A
authors.initials: KA
authors.lastname: Powell
authors.forename: G R
authors.initials: GR
authors.lastname: Hickson
authors.forename: M F
authors.initials: MF
authors.lastname: Bader
authors.forename: G W
authors.initials: GW
authors.lastname: Gould
mesh_terms: D016475:3T3 Cells; D020823:ADP-Ribosylation Factor 1; D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors; D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003847:Deoxyglucose / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000494:pharmacology*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D009227:Myristic Acids / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D011990:Receptors, Transferrin / Q000378:metabolism
chemical_list: D000089982:ADP-Ribosylation Factor 6; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D007328:Insulin; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D009227:Myristic Acids; D010446:Peptide Fragments; D011990:Receptors, Transferrin; C495678:Slc2a1 protein, mouse; C495693:Slc2a4 protein, mouse; D003847:Deoxyglucose; D019204:GTP-Binding Proteins; D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors; C486477:Arf5 protein, mouse; C000715727:Arf6 protein, mouse