Regulation of intermuscular electrical coupling by the Caenorhabditis elegans innexin inx-6.
The innexins represent a highly conserved protein family, the members of which make up the structural components of gap junctions in invertebrates. We have isolated and characterized a Caenorhabditis elegans gene inx-6 that encodes a new member of the innexin family required for the electrical coupling of pharyngeal muscles. inx-6(rr5) mutants complete embryogenesis without detectable abnormalities at restrictive temperature but fail to initiate postembryonic development after hatching. inx-6 is expressed in the pharynx at all larval stages, and an INX-6::GFP fusion protein showed a punctate expression pattern characteristic of gap junction proteins localized to plasma membrane plaques. Video recording and electropharyngeograms revealed that in inx-6(rr5) mutants the anterior pharyngeal (procorpus) muscles were electrically coupled to a lesser degree than the posterior metacorpus muscles, which caused a premature relaxation in the anterior pharynx and interfered with feeding. Dye-coupling experiments indicate that the gap junctions that link the procorpus to the metacorpus are functionally compromised in inx-6(rr5) mutants. We also show that another C. elegans innexin, EAT-5, can partially substitute for INX-6 function in vivo, underscoring their likely analogous function.
Li
Shaolin
S
Department of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1.
Dent
Joseph A
JA
Roy
Richard
R
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000502:physiology*; D003001:Cloning, Molecular; D004553:Electric Conductivity; D004625:Embryo, Nonmammalian / Q000378:metabolism / Q000502:physiology; D017629:Gap Junctions / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D009154:Mutation; D010609:Pharyngeal Muscles / Q000502:physiology*
D029742:Caenorhabditis elegans Proteins