title: Sept8 controls the binding of vesicle-associated membrane protein 2 to synaptophysin.
abstract: Septins, a conserved family of GTP/GDP-binding proteins, are present in organisms as diverse as yeast and mammals. We analyzed the distribution of five septins, Sept6, Sept7, Sept8, Sept9 and Sept11, in various rat tissues by western blot analyses and found all septins to be expressed in brain. We also examined the developmental changes of expression of these septins in the rat brain and found that the level of Sept8 increased during post-natal development. Morphological analyses revealed that Sept8 is enriched at pre-synapses. Using yeast two-hybrid screening, we identified vesicle-associated membrane protein 2 (VAMP2), a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE), as an interacting protein for Sept8. Synaptophysin is reported to associate with and recruit VAMP2 to synaptic vesicles and dissociate prior to forming the SNARE complex consisting of VAMP2, syntaxin and synaptosome-associated protein of 25 kDa. We showed that Sept8 suppresses the interaction between VAMP2 and synaptophysin through binding to VAMP2. In addition, we found that Sept8 forms a complex with syntaxin1A, and the Sept8-VAMP2 interaction is disrupted by synaptosome-associated protein of 25 kDa. These results suggest that Sept8 may participate in the process of the SNARE complex formation and subsequent neurotransmitter release.
authors.affiliation: Institute for Developmental Research, Aichi Human Service Center, Kasugai, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Ito
authors.forename: Kimie
authors.initials: K
authors.lastname: Atsuzawa
authors.forename: Rika
authors.initials: R
authors.lastname: Morishita
authors.forename: Nobuteru
authors.initials: N
authors.lastname: Usuda
authors.forename: Kaori
authors.initials: K
authors.lastname: Sudo
authors.forename: Ikuko
authors.initials: I
authors.lastname: Iwamoto
authors.forename: Kosuke
authors.initials: K
authors.lastname: Mizutani
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Katoh-Semba
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nozawa
authors.forename: Tomiko
authors.initials: T
authors.lastname: Asano
authors.forename: Koh-ichi
authors.initials: K
authors.lastname: Nagata
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000648:ultrastructure; D002460:Cell Line; D005089:Exocytosis / Q000502:physiology; D005260:Female; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008561:Membrane Fusion / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding / Q000502:physiology; D051381:Rats; D050600:SNARE Proteins / Q000378:metabolism; D058112:Septins; D013347:Subcellular Fractions; D013570:Synaptic Membranes / Q000378:metabolism* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism / Q000648:ultrastructure; D016708:Synaptophysin / Q000378:metabolism*; D050825:Synaptosomal-Associated Protein 25 / Q000378:metabolism; D050827:Syntaxin 1 / Q000378:metabolism; D050988:Vesicle-Associated Membrane Protein 2 / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D050600:SNARE Proteins; C494210:Snap25 protein, rat; D016708:Synaptophysin; D050825:Synaptosomal-Associated Protein 25; D050827:Syntaxin 1; C494706:Vamp2 protein, rat; D050988:Vesicle-Associated Membrane Protein 2; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; C464445:SEPTIN8 protein, human; C539978:Septin8 protein, rat; D058112:Septins