title: mVps45 knockdown selectively modulates VAMP expression in 3T3-L1 adipocytes.
abstract: Insulin stimulates the delivery of glucose transporter-4 (GLUT4)-containing vesicles to the surface of adipocytes. Depletion of the Sec1/Munc18 protein mVps45 significantly abrogates insulin-stimulated glucose transport and GLUT4 translocation. Here we show that depletion of mVps45 selectively reduced expression of VAMPs 2 and 4, but not other VAMP isoforms. Although we did not observe direct interaction of mVps45 with any VAMP isoform; we found that the cognate binding partner of mVps45, Syntaxin 16 associates with VAMPs 2, 4, 7 and 8 in vitro. Co-immunoprecipitation experiments in 3T3-L1 adipocytes revealed an interaction between Syntaxin 16 and only VAMP4. We suggest GLUT4 trafficking is controlled by the coordinated expression of mVps45/Syntaxin 16/VAMP4, and that depletion of mVps45 regulates VAMP2 levels indirectly, perhaps via reduced trafficking into specialized subcellular compartments.
authors.affiliation: Henry Wellcome Laboratory of Cell Biology; Institute of Molecular; Cell and Systems Biology; College of Medical; Veterinary and Life Sciences; University of Glasgow ; Glasgow, Scotland.
authors.forename: Jessica B A
authors.initials: JB
authors.lastname: Sadler
authors.affiliation: Henry Wellcome Laboratory of Cell Biology; Institute of Molecular; Cell and Systems Biology; College of Medical; Veterinary and Life Sciences; University of Glasgow ; Glasgow, Scotland.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Roccisana
authors.affiliation: Henry Wellcome Laboratory of Cell Biology; Institute of Molecular; Cell and Systems Biology; College of Medical; Veterinary and Life Sciences; University of Glasgow ; Glasgow, Scotland.
authors.forename: Minttu
authors.initials: M
authors.lastname: Virolainen
authors.affiliation: Department of Biology; University of York ; Heslington, York.
authors.forename: Nia J
authors.initials: NJ
authors.lastname: Bryant
authors.affiliation: Henry Wellcome Laboratory of Cell Biology; Institute of Molecular; Cell and Systems Biology; College of Medical; Veterinary and Life Sciences; University of Glasgow ; Glasgow, Scotland.
authors.forename: Gwyn W
authors.initials: GW
authors.lastname: Gould
keywords: SNARE proteins; VAMP; adipocyte; biochemistry; cell biology; glucose transport; hormones; insulin; intracellular membranes; membrane protein trafficking; membrane trafficking