title: MUP-4 is a novel transmembrane protein with functions in epithelial cell adhesion in Caenorhabditis elegans.
abstract: Tissue functions and mechanical coupling of cells must be integrated throughout development. A striking example of this coupling is the interactions of body wall muscle and hypodermal cells in Caenorhabditis elegans. These tissues are intimately associated in development and their interactions generate structures that provide a continuous mechanical link to transmit muscle forces across the hypodermis to the cuticle. Previously, we established that mup-4 is essential in embryonic epithelial (hypodermal) morphogenesis and maintenance of muscle position. Here, we report that mup-4 encodes a novel transmembrane protein that is required for attachments between the apical epithelial surface and the cuticular matrix. Its extracellular domain includes epidermal growth factor-like repeats, a von Willebrand factor A domain, and two sea urchin enterokinase modules. Its intracellular domain is homologous to filaggrin, an intermediate filament (IF)-associated protein that regulates IF compaction and that has not previously been reported as part of a junctional complex. MUP-4 colocalizes with epithelial hemidesmosomes overlying body wall muscles, beginning at the time of embryonic cuticle maturation, as well as with other sites of mechanical coupling. These findings support that MUP-4 is a junctional protein that functions in IF tethering, cell-matrix adherence, and mechanical coupling of tissues.
authors.affiliation: Department of Cell and Developmental Biology, University of Pennsylvania, School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: L
authors.initials: L
authors.lastname: Hong
authors.forename: T
authors.initials: T
authors.lastname: Elbl
authors.forename: J
authors.initials: J
authors.lastname: Ward
authors.forename: C
authors.initials: C
authors.lastname: Franzini-Armstrong
authors.forename: K K
authors.initials: KK
authors.lastname: Rybicka
authors.forename: B K
authors.initials: BK
authors.lastname: Gatewood
authors.forename: D L
authors.initials: DL
authors.lastname: Baillie
authors.forename: E A
authors.initials: EA
authors.lastname: Bucher
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins; D002448:Cell Adhesion / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D049452:Green Fluorescent Proteins; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism; D022002:Hemidesmosomes / Q000378:metabolism; D007814:Larva / Q000378:metabolism / Q000648:ultrastructure; D008164:Luminescent Proteins / Q000235:genetics; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism / Q000648:ultrastructure; D009154:Mutation; D009928:Organ Specificity; D020161:Physical Chromosome Mapping; D012330:RNA, Double-Stranded / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D029742:Caenorhabditis elegans Proteins; D015815:Cell Adhesion Molecules; D015801:Helminth Proteins; D008164:Luminescent Proteins; C432913:MUP-4 protein, C elegans; D008565:Membrane Proteins; D012330:RNA, Double-Stranded; D049452:Green Fluorescent Proteins