title: V-type ATPase is involved in biogenesis of GLUT4 vesicles.
abstract: Proton pumps participate in several aspects of endocytic protein trafficking. However, their involvement specifically in the GLUT4 pathway has been a matter of great controversy. Here, we report that incubation of 3T3-L1 adipocytes with specific inhibitors of V-type ATPase, concanamycin A and bafilomycin A1, inhibits insulin-regulated glucose transport and results in accumulation of GLUT4 in heavy, rapidly sedimenting intracellular membranes. Correspondingly, the amount of small responsive GLUT4 vesicles in concanamycin A- and bafilomycin A1-treated cells is decreased. We conclude that these drugs block translocation of GLUT4 in adipose cells by inhibiting formation of small insulin-responsive vesicles on donor intracellular membranes. At the same time, proton pump inhibitors do not affect insulin-dependent translocation of preexisting vesicles or GLUT4 sorting in recycling endosomes. On the contrary, wortmannin acutely inhibits insulin-dependent translocation of the preexisting vesicles but has no effect on vesicle formation.
authors.affiliation: Boston University School of Medicine, Boston, Massachusetts 02118, USA.
authors.forename: Marina
authors.initials: M
authors.lastname: Malikova
authors.forename: Jun
authors.initials: J
authors.lastname: Shi
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Kandror
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000201:enzymology / Q000378:metabolism*; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051275:Glucose Transporter Type 4; D006801:Humans; D007328:Insulin / Q000502:physiology; D018942:Macrolides / Q000494:pharmacology; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D022161:Transport Vesicles / Q000378:metabolism*; D025262:Vacuolar Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000502:physiology*; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D004791:Enzyme Inhibitors; D051275:Glucose Transporter Type 4; D007328:Insulin; D018942:Macrolides; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495692:SLC2A4 protein, human; C495693:Slc2a4 protein, mouse; C036978:concanamycin A; C040929:bafilomycin A1; D025262:Vacuolar Proton-Translocating ATPases; D000077191:Wortmannin