title: The Caenorhabditis elegans paxillin orthologue, PXL-1, is required for pharyngeal muscle contraction and for viability.
abstract: We have identified the gene C28H8.6 (pxl-1) as the Caenorhabditis elegans orthologue of vertebrate paxillin. PXL-1 contains the four C-terminal LIM domains conserved in paxillin across all species and three of the five LD motifs found in the N-terminal half of most paxillins. In body wall muscle, PXL-1 antibodies and a full-length green fluorescent protein translational fusion localize to adhesion sites in the sarcomere, the functional repeat unit in muscle responsible for contraction. PXL-1 also localizes to ring-shaped structures near the sarcolemma in pharyngeal muscle corresponding to podosome-like sites of actin attachment. Our analysis of a loss-of-function allele of pxl-1, ok1483, shows that loss of paxillin leads to early larval arrested animals with paralyzed pharyngeal muscles and eventual lethality, presumably due to an inability to feed. We rescued the mutant phenotype by expressing paxillin solely in the pharynx and found that these animals survived and are essentially wild type in movement and body wall muscle structure. This indicates a differential requirement for paxillin in these two types of muscle. In pharyngeal muscle it is essential for contraction, whereas in body wall muscle it is dispensable for filament assembly, sarcomere stability, and ultimately movement.
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Adam
authors.initials: A
authors.lastname: Warner
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Qadota
authors.forename: Guy M
authors.initials: GM
authors.lastname: Benian
authors.forename: A Wayne
authors.initials: AW
authors.lastname: Vogl
authors.forename: Donald G
authors.initials: DG
authors.lastname: Moerman
mesh_terms: D008841:Actin Cytoskeleton / Q000648:ultrastructure; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002470:Cell Survival / Q000235:genetics; D005804:Genes, Lethal; D047908:Intracellular Signaling Peptides and Proteins; D007814:Larva / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D009119:Muscle Contraction; D009154:Mutation; D051419:Paxillin / Q000235:genetics / Q000502:physiology*; D010609:Pharyngeal Muscles / Q000378:metabolism / Q000502:physiology*; D010641:Phenotype; D020033:Protein Isoforms / Q000235:genetics; D017434:Protein Structure, Tertiary; D012518:Sarcomeres / Q000502:physiology
chemical_list: D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D051419:Paxillin; D020033:Protein Isoforms; C489652:Unc-95 protein, C elegans