title: Differential expression of SNAP-25 family proteins in the mouse brain.
abstract: Soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP)-25 is a neuronal SNARE protein essential for neurotransmitter release from presynaptic terminals. Three palmitoylated SNAP-25 family proteins: SNAP-25a, SNAP-25b, and SNAP-23, are expressed in the brain, but little is known about their distributions and functions. In the present study, we generated specific antibodies to distinguish these three homologous proteins. Immunoblot and immunohistochemical analyses revealed that SNAP-25b was distributed in synapse-enriched regions throughout almost the entire brain, whereas SNAP-25a and SNAP-23 were expressed in relatively specific brain regions with partially complementary expression patterns. SNAP-25a and SNAP-25b, but not SNAP-23, were also present in the axoplasm of nerve fibers. The intracellular localization was also different, and although SNAP-25b and SNAP-23 were found primarily in membrane and lipid raft-enriched fractions of mouse brain homogenates, a substantial amount of SNAP-25a was recovered in soluble fractions. In PC12 cells, SNAP-25b was localized to the plasma membrane, but SNAP-25a and SNAP-23 were distributed throughout the cytoplasm. The expression and distribution of these three proteins were also differentially regulated in the early postnatal period. These results indicate that the three SNAP-25 family proteins display a differential distribution in the brain as well as in neuronal cells, and possibly play distinct roles.
authors.affiliation: Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
authors.forename: Saori
authors.initials: S
authors.lastname: Yamamori
authors.forename: Makoto
authors.initials: M
authors.lastname: Itakura
authors.forename: Daichi
authors.initials: D
authors.lastname: Sugaya
authors.forename: Osamu
authors.initials: O
authors.lastname: Katsumata
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sakagami
authors.forename: Masami
authors.initials: M
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D016716:PC12 Cells; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D050825:Synaptosomal-Associated Protein 25 / Q000235:genetics / Q000378:metabolism*
chemical_list: D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; C494209:Snap25 protein, mouse; D050825:Synaptosomal-Associated Protein 25