Insulin-stimulated translocation of GLUT4 glucose transporters requires SNARE-complex proteins.
A major physiological role of insulin is the regulation of glucose uptake into skeletal and cardiac muscle and adipose tissue, mediated by an insulin-stimulated translocation of GLUT4 glucose transporters from an intracellular vesicular pool to the plasma membrane. This process is similar to the regulated docking and fusion of vesicles in neuroendocrine cells, a process that involves SNARE-complex proteins. Recently, several SNARE proteins were found in adipocytes: vesicle-associated membrane protein (VAMP-2), its related homologue cellubrevin, and syntaxin-4. In this report we show that treatment of permeabilized 3T3-L1 adipocytes with botulinum neurotoxin D, which selectively cleaves VAMP-2 and cellubrevin, inhibited the ability of insulin to stimulate translocation of GLUT4 vesicles to the plasma membrane. Furthermore, treatment of the permeabilized adipocytes with glutathione S-transferase fusion proteins encoding soluble forms of VAMP-2 or syntaxin-4 also effectively blocked insulin-regulated GLUT4 translocation. These results provide evidence of a functional role for SNARE-complex proteins in insulin-stimulated glucose uptake and suggest that adipocytes utilize a mechanism of regulating vesicle docking and fusion analogous to that found in neuroendocrine tissues.
Cheatham
B
B
Research Division, Joslin Diabetes Center, Boston, MA 02215, USA. cheathab@joslab.harvard.edu
Volchuk
A
A
Kahn
C R
CR
Wang
L
L
Rhodes
C J
CJ
Klip
A
A
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology; D002454:Cell Differentiation; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D051275:Glucose Transporter Type 4; D005982:Glutathione Transferase / Q000096:biosynthesis; D007328:Insulin / Q000494:pharmacology*; D008565:Membrane Proteins / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D009004:Monosaccharide Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D009124:Muscle Proteins; D009419:Nerve Tissue Proteins / Q000378:metabolism; D015388:Organelles / Q000378:metabolism; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D050600:SNARE Proteins; D051040:Vesicle-Associated Membrane Protein 3; D033921:Vesicular Transport Proteins
D051275:Glucose Transporter Type 4; D007328:Insulin; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D011993:Recombinant Fusion Proteins; D050600:SNARE Proteins; C495693:Slc2a4 protein, mouse; D051040:Vesicle-Associated Membrane Protein 3; D033921:Vesicular Transport Proteins; C096325:botulinum toxin type D; D003907:Dexamethasone; D005982:Glutathione Transferase; D001905:Botulinum Toxins; D015056:1-Methyl-3-isobutylxanthine