title: Variations in the requirement for v-SNAREs in GLUT4 trafficking in adipocytes.
abstract: Vesicle transport in eukaryotic cells is regulated by SNARE proteins, which play an intimate role in regulating the specificity of vesicle fusion between discrete intracellular organelles. In the present study we investigated the function and plasticity of v-SNAREs in insulin-regulated GLUT4 trafficking in adipocytes. Using a combination of knockout mice, v-SNARE cleavage by clostridial toxins and total internal reflection fluorescence microscopy, we interrogated the function of VAMPs 2, 3 and 8 in this process. Our studies reveal that the simultaneous disruption of VAMPs 2, 3 and 8 completely inhibited insulin-stimulated GLUT4 insertion into the plasma membrane, due to a block in vesicle docking at the plasma membrane. These defects could be rescued by re-expression of VAMP2, VAMP3 or VAMP8 alone, but not VAMP7. These data indicate a plasticity in the requirement for v-SNAREs in GLUT4 trafficking to the plasma membrane and further define an important role for the v-SNARE proteins in pre-fusion docking of vesicles.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhao
authors.forename: Lu
authors.initials: L
authors.lastname: Yang
authors.forename: Jamie A
authors.initials: JA
authors.lastname: Lopez
authors.forename: Junmei
authors.initials: J
authors.lastname: Fan
authors.forename: James G
authors.initials: JG
authors.lastname: Burchfield
authors.forename: Li
authors.initials: L
authors.lastname: Bai
authors.forename: Wanjin
authors.initials: W
authors.lastname: Hong
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.forename: David E
authors.initials: DE
authors.lastname: James
mesh_terms: D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D051275:Glucose Transporter Type 4 / Q000235:genetics / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D021381:Protein Transport; D050683:R-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D050988:Vesicle-Associated Membrane Protein 2 / Q000235:genetics / Q000378:metabolism*; D051040:Vesicle-Associated Membrane Protein 3 / Q000235:genetics / Q000378:metabolism*
chemical_list: D051275:Glucose Transporter Type 4; D007328:Insulin; D050683:R-SNARE Proteins; C496927:Sybl1 protein, mouse; C491831:Vamp8 protein, mouse; D050988:Vesicle-Associated Membrane Protein 2; D051040:Vesicle-Associated Membrane Protein 3