title: The secretory granule-associated protein CAPS2 regulates neurotrophin release and cell survival.
abstract: Neurotrophins are key modulators of various neuronal functions, including differentiation, survival, and synaptic plasticity, but the molecules that regulate their secretion are poorly understood. We isolated a clone that is predominantly expressed in granule cells of postnatally developing mouse cerebellum, which turned out to be a paralog of CAPS (Ca2+-dependent activator protein for secretion), and named CAPS2. CAPS2 is enriched on vesicular structures of presynaptic parallel fiber terminals of granule cells connecting postsynaptic spines of Purkinje cell dendrites. Vesicle factions affinity-purified by the CAPS2 antibody from mouse cerebella contained significant amounts of neurotrophin-3 (NT-3), brain-derived neurotrophic factor (BDNF), and chromogranin B but not marker proteins for synaptic vesicle synaptophysin and synaptotagmin. In cerebellar primary cultures, punctate CAPS2 immunoreactivities are primarily colocalized with those of NT-3 and BDNF and near those of a postsynaptic marker, postsynaptic density-95, around dendritic arborization of Purkinje cells. Exogenously expressed CAPS2 enhanced release of exogenous NT-3 and BDNF from PC12 cells and endogenous NT-3 from cultured granule cells in a depolarization-dependent manner. Moreover, the overexpression of CAPS2 in granule cells promotes the survival of Purkinje cells in cerebellar cultures. Thus, we suggest that CAPS2 mediates the depolarization-dependent release of NT-3 and BDNF from granule cells, leading to regulation in cell differentiation and survival during cerebellar development.
authors.affiliation: Laboratory for Molecular Neurogenesis, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan.
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Sadakata
authors.forename: Akira
authors.initials: A
authors.lastname: Mizoguchi
authors.forename: Yumi
authors.initials: Y
authors.lastname: Sato
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Katoh-Semba
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Fukuda
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Mikoshiba
authors.forename: Teiichi
authors.initials: T
authors.lastname: Furuichi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000254:growth & development / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D002470:Cell Survival; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D005089:Exocytosis; D006801:Humans; D017403:In Situ Hybridization; D051379:Mice; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000032:analysis / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D009474:Neurons / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D016716:PC12 Cells; D017729:Presynaptic Terminals / Q000737:chemistry; D011689:Purkinje Cells / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D022142:Secretory Vesicles / Q000737:chemistry*; D016415:Sequence Alignment
chemical_list: C480975:CAPS2 protein, mouse; D002135:Calcium-Binding Proteins; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger