title: The non-neuronal syntaxin SYN-1 regulates defecation behavior and neural activity in C. elegans through interaction with the Munc13-like protein AEX-1.
abstract: We have previously shown that the AEX-1 protein, which is expressed in postsynaptic muscles, retrogradely regulates presynaptic neural activity at the Caenorhabditis elegans neuromuscular junctions. AEX-1 is similar to vertebrate Munc13-4 protein, suggesting a function for vesicle exocytosis from a kind of cells. Compared to emerging evidences of the role of Munc13 proteins in synaptic vesicle release, however, the precise mechanism for vesicle exocytosis by AEX-1 and Munc13-4 is little understood. Here we have identified SYN-1 as a candidate molecule of AEX-1-dependent vesicle exocytosis from non-neuronal cells. The syn-1 gene encodes a C. elegans syntaxin, which is distantly related to the neuronal syntaxin UNC-64. The syn-1 gene is predominantly expressed in non-neuronal tissues and genetically interacts with aex-1 for presynaptic activity. However, the two proteins did not interact physically in our yeast two-hybrid system and mutational SYN-1 did not bypass the requirement of AEX-1 for the behavioral defects in aex-1 mutants, whereas mutant UNC-64 does in unc-13 mutants. These results suggest that a novel molecular interaction between the AEX-1 and syntaxin may regulate vesicle exocytosis for retrograde signal release.
authors.affiliation: Neuroscience Research Institute, AIST, Tsukuba Central 6, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamashita
authors.forename: Kouichi
authors.initials: K
authors.lastname: Iwasaki
authors.forename: Motomichi
authors.initials: M
authors.lastname: Doi
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D003672:Defecation / Q000235:genetics; D005089:Exocytosis; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000502:physiology; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000502:physiology*; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D013572:Synaptic Vesicles / Q000378:metabolism*; D050827:Syntaxin 1 / Q000235:genetics / Q000378:metabolism*
chemical_list: C446288:AEX-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins; D050827:Syntaxin 1; C534480:syx-3 protein, C elegans