Zebrafish integrin-linked kinase is required in skeletal muscles for strengthening the integrin-ECM adhesion complex.
Mechanical instability of skeletal muscle cells is the major cause of congenital muscular dystrophy. Here we show that the zebrafish lost-contact mutant, that lacks a functional integrin-linked kinase (ilk) gene, suffers from mechanical instability of skeletal muscle fibres. With genetic and morpholino knock-down experiments we demonstrate that: 1) laminin, itgalpha7, Ilk and beta-parvin are all critical for mechanical stability in skeletal muscles. 2) Ilk acts redundantly with the dystrophin/dystroglycan adhesion complex in maintaining mechanical stability of skeletal muscles. 3) Ilk protein is recruited to the myotendinous junctions, which requires the ECM component laminin and the presence of itgalpha7 in the sarcolemma. 4) Ilk, unexpectedly, is dispensable for formation of the adhesion complex. Ilk, however, is required for strengthening the adhesion of the muscle fibre with the ECM and this activity requires the presence of a functional kinase domain in Ilk. 5) We identified a novel interaction between Ilk and the mechanical stretch sensor protein MLP. Thus, Ilk is an essential intracellular component downstream of laminin and itgalpha7, providing strengthening of skeletal muscle fibre adhesion with the ECM and therefore qualified as a novel candidate gene for congenital muscular dystrophy.
Postel
Ruben
R
Hubrecht Institute and University Medical Centre Utrecht, The Netherlands.
Vakeel
Padmanabhan
P
Topczewski
Jacek
J
Knöll
Ralph
R
Bakkers
Jeroen
J
D000185:Actinin / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology*; D003599:Cytoskeleton / Q000378:metabolism; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D039001:Integrin alpha Chains / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D007797:Laminin / Q000235:genetics / Q000378:metabolism; D054461:Lim Kinases / Q000235:genetics / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D051419:Paxillin / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D010802:Phylogeny; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D015027:Zebrafish / Q000033:anatomy & histology / Q000196:embryology / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D000099200:Scaffold Protein ILK
D000185:Actinin; D015703:Antigens, CD; D039001:Integrin alpha Chains; D007797:Laminin; D054461:Lim Kinases; D016376:Oligonucleotides, Antisense; D051419:Paxillin; D017346:Protein Serine-Threonine Kinases; D011993:Recombinant Fusion Proteins; D029961:Zebrafish Proteins; C522179:LAMA4 protein, zebrafish; C085725:integrin alpha7; C496064:pxna protein, zebrafish; C522180:ILK protein, zebrafish; D000099200:Scaffold Protein ILK