title: Tmem2 regulates cell-matrix interactions that are essential for muscle fiber attachment.
abstract: Skeletal muscle morphogenesis depends upon interactions between developing muscle fibers and the extracellular matrix (ECM) that anchors fibers to the myotendinous junction (MTJ). The pathways that organize the ECM and regulate its engagement by cell-matrix adhesion complexes (CMACs) are therefore essential for muscle integrity. Here, we demonstrate the impact of transmembrane protein 2 (tmem2) on cell-matrix interactions during muscle morphogenesis in zebrafish. Maternal-zygotic tmem2 mutants (MZtmem2) exhibit muscle fiber detachment, in association with impaired laminin organization and ineffective fibronectin degradation at the MTJ. Similarly, disorganized laminin and fibronectin surround MZtmem2 cardiomyocytes, which could account for their hindered movement during cardiac morphogenesis. In addition to ECM defects, MZtmem2 mutants display hypoglycosylation of α-dystroglycan within the CMAC, which could contribute to the observed fiber detachment. Expression of the Tmem2 ectodomain can rescue aspects of the MZtmem2 phenotype, consistent with a possible extracellular function of Tmem2. Together, our results suggest that Tmem2 regulates cell-matrix interactions by affecting both ECM organization and CMAC activity. These findings evoke possible connections between the functions of Tmem2 and the etiologies of congenital muscular dystrophies, particularly dystroglycanopathies.
authors.affiliation: Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Lucile
authors.identifier: 0000-0001-7927-2006
authors.initials: L
authors.lastname: Ryckebüsch
authors.affiliation: Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Lydia
authors.identifier: 0000-0001-5883-9325
authors.initials: L
authors.lastname: Hernandez
authors.affiliation: Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Carole
authors.identifier: 0000-0003-4717-3024
authors.initials: C
authors.lastname: Wang
authors.affiliation: Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Jenny
authors.identifier: 0000-0002-1894-2560
authors.initials: J
authors.lastname: Phan
authors.affiliation: Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA dyelon@ucsd.edu.
authors.forename: Deborah
authors.identifier: 0000-0003-3523-4053
authors.initials: D
authors.lastname: Yelon
mesh_terms: D000818:Animals; D021982:Cell-Matrix Junctions / Q000378:metabolism; D049030:Dystroglycans / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D017403:In Situ Hybridization; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D024510:Muscle Development / Q000235:genetics / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D029961:Zebrafish Proteins; C568068:cemip2 protein, zebrafish; D049030:Dystroglycans
keywords: Cardiac fusion; Extracellular matrix; Muscle morphogenesis; Zebrafish