Rat basophilic leukemia cells express syntaxin-3 and VAMP-7 in granule membranes.
In neuronal cells, it is generally agreed that SNARE proteins underlie the release of neurotransmitter. It is controversial, however, whether they also work functionally in the degranulation of RBL-2H3 cells because the expression of SNARE proteins has not been confirmed and the degranulation is not inhibited by tetanus toxin which cleaves one of SNARE proteins, VAMP-2. We investigated the expression and the localization of SNARE proteins including VAMP-7 which is insensitive to tetanus toxin. RT-PCR analysis showed the existence of SNARE proteins, including syntaxin-2, -3, -4, SNAP-23, VAMP-2, and VAMP-7. Experiments using GFP-conjugated proteins revealed that VAMP-7 was localized only in granule membranes, whereas syntaxin-3 was in both the plasma and granule membranes. Upon antigen stimulation, these proteins in granule membranes moved to the cell surface due to the fusion of granules with the plasma membrane. The results suggest the involvement of SNARE proteins in the degranulation of RBL-2H3 cells.
Hibi
T
T
Faculty of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan.
Hirashima
N
N
Nakanishi
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D001483:Base Sequence; D001491:Basophils / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism / Q000648:ultrastructure; D018274:Electroporation; D049452:Green Fluorescent Proteins; D007425:Intracellular Membranes / Q000378:metabolism; D015471:Leukemia, Basophilic, Acute / Q000378:metabolism*; D008164:Luminescent Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000378:metabolism; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010957:Plasmids; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050600:SNARE Proteins; D014407:Tumor Cells, Cultured; D033921:Vesicular Transport Proteins
D001426:Bacterial Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D050600:SNARE Proteins; C496926:Vamp7 protein, rat; D033921:Vesicular Transport Proteins; C054562:yellow fluorescent protein, Bacteria; D049452:Green Fluorescent Proteins