title: Knockdown of col22a1 gene in zebrafish induces a muscular dystrophy by disruption of the myotendinous junction.
abstract: The myotendinous junction (MTJ) is the major site of force transfer in skeletal muscle, and defects in its structure correlate with a subset of muscular dystrophies. Col22a1 encodes the MTJ component collagen XXII, the function of which remains unknown. Here, we have cloned and characterized the zebrafish col22a1 gene and conducted morpholino-based loss-of-function studies in developing embryos. We showed that col22a1 transcripts localize at muscle ends when the MTJ forms and that COLXXII protein integrates the junctional extracellular matrix. Knockdown of COLXXII expression resulted in muscular dystrophy-like phenotype, including swimming impairment, curvature of embryo trunk/tail, strong reduction of twitch-contraction amplitude and contraction-induced muscle fiber detachment, and provoked significant activation of the survival factor Akt. Electron microscopy and immunofluorescence studies revealed that absence of COLXXII caused a strong reduction of MTJ folds and defects in myoseptal structure. These defects resulted in reduced contractile force and susceptibility of junctional extracellular matrix to rupture when subjected to repeated mechanical stress. Co-injection of sub-phenotypic doses of morpholinos against col22a1 and genes of the major muscle linkage systems showed a synergistic gene interaction between col22a1 and itga7 (α7β1 integrin) that was not observed with dag1 (dystroglycan). Finally, pertinent to a conserved role in humans, the dystrophic phenotype was rescued by microinjection of recombinant human COLXXII. Our findings indicate that COLXXII contributes to the stabilization of myotendinous junctions and strengthens skeletal muscle attachments during contractile activity.
authors.affiliation: Institut de Génomique Fonctionnelle de Lyon, ENS de Lyon, UMR CNRS 5242, Université Lyon 1, 46 Allée d'Italie, 69364 Lyon cedex 07, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Charvet
authors.forename: Alexandre
authors.initials: A
authors.lastname: Guiraud
authors.forename: Marilyne
authors.initials: M
authors.lastname: Malbouyres
authors.forename: Daniela
authors.initials: D
authors.lastname: Zwolanek
authors.forename: Emilie
authors.initials: E
authors.lastname: Guillon
authors.forename: Sandrine
authors.initials: S
authors.lastname: Bretaud
authors.forename: Catherine
authors.initials: C
authors.lastname: Monnot
authors.forename: Jörg
authors.initials: J
authors.lastname: Schulze
authors.forename: Hannah L
authors.initials: HL
authors.lastname: Bader
authors.forename: Bruno
authors.initials: B
authors.lastname: Allard
authors.forename: Manuel
authors.initials: M
authors.lastname: Koch
authors.forename: Florence
authors.initials: F
authors.lastname: Ruggiero
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D003094:Collagen / Q000235:genetics* / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D055785:Gene Knockdown Techniques; D006801:Humans; D016023:Integrins / Q000378:metabolism; D008322:Mammals; D008845:Microinjections; D060172:Morpholinos / Q000494:pharmacology; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D018908:Muscle Weakness / Q000378:metabolism / Q000473:pathology; D009137:Muscular Dystrophy, Animal / Q000196:embryology / Q000235:genetics / Q000473:pathology*; D010641:Phenotype; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013710:Tendons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D015027:Zebrafish / Q000235:genetics*
chemical_list: D016023:Integrins; D060172:Morpholinos; D012333:RNA, Messenger; D003094:Collagen; D051057:Proto-Oncogene Proteins c-akt; C082908:integrin alpha7beta1
keywords: Collagen; Extracellular matrix; Muscular dystrophy; Myotendinous junction; Skeletal muscle; Zebrafish