TY - JOUR
T1 - Syndet, an adipocyte target SNARE involved in the insulin-induced translocation of GLUT4 to the cell surface
AU - Rea, Shane
AU - Martin, Laura B.
AU - McIntosh, Shane
AU - Macaulay, S. Lance
AU - Ramsdale, Tracie
AU - Baldini, Giulia
AU - James, David E.
PY - 1998/7/24
Y1 - 1998/7/24
N2 - In adipocytes, insulin stimulates the translocation of the glucose transporter, GLUT4, from an intracellular storage compartment to the cell surface. Substantial evidence exists to suggest that in the basal state GLUT4 resides in discrete storage vesicles. A direct interaction of GLUT4 storage vesicles with the plasma membrane has been implicated because the v-SNARE, vesicle-associated membrane protein-2 (VAMP2), appears to be a specific component of these vesicles. In the present study we sought to identify the cognate target SNAREs for VAMP2 in mouse 3T3-L1 adipocytes. Membrane fractions were isolated from adipocytes and probed by far Western blotting with the cytosolic portion of VAMP2 fused to glutathione S-transferase. Two plasma membrane-enriched proteins, p25 and p35, were specifically labeled with this probe. By using a combination of immunoblotting, detergent extraction, and anion exchange chromatography, we identified p35 as Syntaxin- 4 and p25 as the recently identified murine SNAP-25 homologue, Syndet (mSNAP- 23). By using surface plasmon resonance we show that VAMP2, Syntaxin-4, and Syndet form a ternary SDS-resistant SNARE complex. Microinjection of anti- Syndet antibodies into 3T3-L1 adipocytes, or incubation of permeabilized adipocytes with a synthetic peptide comprising the C-terminal 24 amino acids of Syndet, inhibited insulin-stimulated GLUT4 translocation to the cell surface by ~40%. GLUT1 trafficking remained unaffected by the presence of the peptide. Our data suggest that Syntaxin-4 and Syndet are important cell- surface target SNAREs within adipocytes that regulate docking and fusion of GLUT-4-containing vesicles with the plasma membrane in response to insulin.
AB - In adipocytes, insulin stimulates the translocation of the glucose transporter, GLUT4, from an intracellular storage compartment to the cell surface. Substantial evidence exists to suggest that in the basal state GLUT4 resides in discrete storage vesicles. A direct interaction of GLUT4 storage vesicles with the plasma membrane has been implicated because the v-SNARE, vesicle-associated membrane protein-2 (VAMP2), appears to be a specific component of these vesicles. In the present study we sought to identify the cognate target SNAREs for VAMP2 in mouse 3T3-L1 adipocytes. Membrane fractions were isolated from adipocytes and probed by far Western blotting with the cytosolic portion of VAMP2 fused to glutathione S-transferase. Two plasma membrane-enriched proteins, p25 and p35, were specifically labeled with this probe. By using a combination of immunoblotting, detergent extraction, and anion exchange chromatography, we identified p35 as Syntaxin- 4 and p25 as the recently identified murine SNAP-25 homologue, Syndet (mSNAP- 23). By using surface plasmon resonance we show that VAMP2, Syntaxin-4, and Syndet form a ternary SDS-resistant SNARE complex. Microinjection of anti- Syndet antibodies into 3T3-L1 adipocytes, or incubation of permeabilized adipocytes with a synthetic peptide comprising the C-terminal 24 amino acids of Syndet, inhibited insulin-stimulated GLUT4 translocation to the cell surface by ~40%. GLUT1 trafficking remained unaffected by the presence of the peptide. Our data suggest that Syntaxin-4 and Syndet are important cell- surface target SNAREs within adipocytes that regulate docking and fusion of GLUT-4-containing vesicles with the plasma membrane in response to insulin.
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U2 - 10.1074/jbc.273.30.18784
DO - 10.1074/jbc.273.30.18784
M3 - Article
C2 - 9668052
AN - SCOPUS:0032563194
VL - 273
SP - 18784
EP - 18792
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 30
ER -