1. The t-SNAREs syntaxin4 and SNAP23 but not v-SNARE VAMP2 are indispensable to tether GLUT4 vesicles at the plasma membrane in adipocyte
- Author
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Mari Yoshikawa, Masato Kasuga, Sanshiro Tateya, Yoshikazu Tamori, Takayuki Kawaguchi, Naonobu Nishino, and Hajime Kanda
- Subjects
Vesicle fusion ,Vesicle-Associated Membrane Protein 2 ,Biophysics ,Biology ,Biochemistry ,Membrane Fusion ,Vesicle tethering ,Exocytosis ,Mice ,3T3-L1 Cells ,SNAP23 ,Adipocytes ,Animals ,Insulin ,Qc-SNARE Proteins ,Molecular Biology ,Glucose Transporter Type 4 ,VAMP2 ,Tethering ,Qa-SNARE Proteins ,Vesicle ,Cell Membrane ,Cytoplasmic Vesicles ,Cell Biology ,Qb-SNARE Proteins ,Cell biology ,Protein Transport ,Glucose ,Porosome ,RNA Interference ,biological phenomena, cell phenomena, and immunity ,hormones, hormone substitutes, and hormone antagonists - Abstract
SNARE proteins (VAMP2, syntaxin4, and SNAP23) have been thought to play a key role in GLUT4 trafficking by mediating the tethering, docking and subsequent fusion of GLUT4-containing vesicles with the plasma membrane. The precise functions of these proteins have remained elusive, however. We have now shown that depletion of the vesicle SNARE (v-SNARE) VAMP2 by RNA interference in 3T3-L1 adipocytes inhibited the fusion of GLUT4 vesicles with the plasma membrane but did not affect tethering of the vesicles to the membrane. In contrast, depletion of the target SNAREs (t-SNAREs) syntaxin4 or SNAP23 resulted in impairment of GLUT4 vesicle tethering to the plasma membrane. Our results indicate that the t-SNAREs syntaxin4 and SNAP23 are indispensable for the tethering of GLUT4 vesicles to the plasma membrane, whereas the v-SNARE VAMP2 is not required for this step but is essential for the subsequent fusion event.
- Published
- 2010