Insulin recruits GLUT4 from specialized VAMP2-carrying vesicles as well as from the dynamic endosomal/trans-golgi network in rat adipocytes

Ramm, Georg, Slot, Jan Willem, James, David E. and Stoorvogel, Willem (2000) Insulin recruits GLUT4 from specialized VAMP2-carrying vesicles as well as from the dynamic endosomal/trans-golgi network in rat adipocytes. Molecular Biology of the Cell, 11 12: 4079-4091. doi:10.1091/mbc.11.12.4079

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Author Ramm, Georg
Slot, Jan Willem
James, David E.
Stoorvogel, Willem
Title Insulin recruits GLUT4 from specialized VAMP2-carrying vesicles as well as from the dynamic endosomal/trans-golgi network in rat adipocytes
Journal name Molecular Biology of the Cell   Check publisher's open access policy
ISSN 1059-1524
1939-4586
Publication date 2000-12
Sub-type Article (original research)
DOI 10.1091/mbc.11.12.4079
Open Access Status File (Publisher version)
Volume 11
Issue 12
Start page 4079
End page 4091
Total pages 13
Place of publication Bethesda, MD, United States
Publisher American Society for Cell Biology
Collection year 2000
Language eng
Abstract Insulin treatment of fat cells results in the translocation of the insulin-responsive glucose transporter type 4, GLUT4, from intracellular compartments to the plasma membrane. However, the precise nature of these intracellular GLUT4-carrying compartments is debated. To resolve the nature of these compartments, we have performed an extensive morphological analysis of GLUT4-containing compartments, using a novel immunocytochemical technique enabling high labeling efficiency and 3-D resolution of cytoplasmic rims isolated from rat epididymal adipocytes. In basal cells, GLUT4 was localized to three morphologically distinct intracellular structures: small vesicles, tubules, and vacuoles. In response to insulin the increase of GLUT4 at the cell surface was compensated by a decrease in small vesicles, whereas the amount in tubules and vacuoles was unchanged. Under basal conditions, many small GLUT4 positive vesicles also contained IRAP (88%) and the v-SNARE, VAMP2 (57%) but not markers of sorting endosomes (EEA1), late endosomes, or lysosomes (lgp120). A largely distinct population of GLUT4 vesicles (56%) contained the cation-dependent mannose 6-phosphate receptor (CD-MPR), a marker protein that shuttles between endosomes and the trans-Golgi network (TGN). In response to insulin, GLUT4 was recruited both from VAMP2 and CD-MPR positive vesicles. However, while the concentration of GLUT4 in the remaining VAMP2-positive vesicles was unchanged, the concentration of GLUT4 in CD-MPR-positive vesicles decreased. Taken together, we provide morphological evidence indicating that, in response to insulin, GLUT4 is recruited to the plasma membrane by fusion of preexisting VAMP2-carrying vesicles as well as by sorting from the dynamic endosomal-TGN system.
Q-Index Code C1
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemistry and Molecular Biosciences
 
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Created: Tue, 10 Jun 2008, 12:36:48 EST