title: Six innexins contribute to electrical coupling of C. elegans body-wall muscle.
abstract: C. elegans body-wall muscle cells are electrically coupled through gap junctions. Previous studies suggest that UNC-9 is an important, but not the only, innexin mediating the electrical coupling. Here we analyzed junctional current (I j ) for mutants of additional innexins to identify the remaining innexin(s) important to the coupling. The results suggest that a total of six innexins contribute to the coupling, including UNC-9, INX-1, INX-10, INX-11, INX-16, and INX-18. The I j deficiency in each mutant was rescued completely by expressing the corresponding wild-type innexin specifically in muscle, suggesting that the innexins function cell-autonomously. Comparisons of I j between various single, double, and triple mutants suggest that the six innexins probably form two distinct populations of gap junctions with one population consisting of UNC-9 and INX-18 and the other consisting of the remaining four innexins. Consistent with their roles in muscle electrical coupling, five of the six innexins showed punctate localization at muscle intercellular junctions when expressed as GFP- or epitope-tagged proteins, and muscle expression was detected for four of them when assessed by expressing GFP under the control of innexin promoters. The results may serve as a solid foundation for further explorations of structural and functional properties of gap junctions in C. elegans body-wall muscle.
authors.affiliation: Department of Neuroscience, University of Connecticut Health Center, Farmington, Connecticut, United States of America.
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.forename: Bojun
authors.initials: B
authors.lastname: Chen
authors.forename: Zeynep F
authors.initials: ZF
authors.lastname: Altun
authors.forename: Maegan J
authors.initials: MJ
authors.lastname: Gross
authors.forename: Alan
authors.initials: A
authors.lastname: Shan
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schuman
authors.forename: David H
authors.initials: DH
authors.lastname: Hall
authors.forename: Zhao-Wen
authors.initials: ZW
authors.lastname: Wang
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D017630:Connexins / Q000235:genetics / Q000378:metabolism*; D055724:Electrophysiological Phenomena; D017629:Gap Junctions / Q000378:metabolism; D005786:Gene Expression Regulation; D009132:Muscles / Q000502:physiology*; D009154:Mutation; D021381:Protein Transport
chemical_list: D029742:Caenorhabditis elegans Proteins; D017630:Connexins