scholarly journals Integrin-linked kinase stabilizes myotendinous junctions and protects muscle from stress-induced damage

2008 ◽  
Vol 180 (5) ◽  
pp. 1037-1049 ◽  
Author(s):  
Hao-Ven Wang ◽  
Ling-Wei Chang ◽  
Klara Brixius ◽  
Sara A. Wickström ◽  
Eloi Montanez ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Basement Membranes ◽  
Skeletal Muscle Regeneration ◽  
Integrin Subunit ◽  
Β1 Integrin ◽  
Progressive Muscular Dystrophy ◽  
Akt Activation ◽  
Impaired Insulin ◽  
Integrin Linked Kinase ◽  
Myotendinous Junctions

Skeletal muscle expresses high levels of integrin-linked kinase (ILK), predominantly at myotendinous junctions (MTJs) and costameres. ILK binds the cytoplasmic domain of β1 integrin and mediates phosphorylation of protein kinase B (PKB)/Akt, which in turn plays a central role during skeletal muscle regeneration. We show that mice with a skeletal muscle–restricted deletion of ILK develop a mild progressive muscular dystrophy mainly restricted to the MTJs with detachment of basement membranes and accumulation of extracellular matrix. Endurance exercise training enhances the defects at MTJs, leads to disturbed subsarcolemmal myofiber architecture, and abrogates phosphorylation of Ser473 as well as phosphorylation of Thr308 of PKB/Akt. The reduction in PKB/Akt activation is accompanied by an impaired insulin-like growth factor 1 receptor (IGF-1R) activation. Coimmunoprecipitation experiments reveal that the β1 integrin subunit is associated with the IGF-1R in muscle cells. Our data identify the β1 integrin–ILK complex as an important component of IGF-1R/insulin receptor substrate signaling to PKB/Akt during mechanical stress in skeletal muscle.

Cell-matrix interactions in the early mouse embryo

1992 ◽  
Vol 50 (1) ◽  
pp. 600-601
Author(s):  
A.E. Sutherland ◽  
P.G. Calarco ◽  
C.H. Damsky
Keyword(s):  
Mouse Embryo ◽  
Giant Cells ◽  
Blastocyst Stage ◽  
Integrin Subunit ◽  
Β1 Integrin ◽  
Cell Stage ◽  
Early Mouse Embryo ◽  
Migratory Activity ◽  
Early Mouse ◽  
Cell Matrix Interactions

Cell-extracellular matrix (ECM) interactions mediated by the integrin family of receptors are critical for morphogenesis and may also play a regulatory role in differentiation during early development. We have examined the onset of expression of individual integrin subunit proteins in the early mouse embryo, and their roles in early morphogenetic events. As detected by immunoprecipitation, the α6, αV, β1, and β3 subunits are detected as early as the 4-cell stage, α5 at the hatched blastocyst stage and αl and α3 following blastocyst attachment. We tested the role of these integrins in the attachment and migratory activity of two cell populations of the early mouse embryo: the trophoblast giant cells, which invade the uterine stroma and ultimately contribute to the chorio-allantoic placenta, and the parietal endoderm, which migrates over the inner surface of the trophoblast and ultimately forms Reichert's membrane and the parietal yolk sac. Experiments were done in serum-free medium on substrates coated with laminin (Ln) and fibronectin (Fn). Trophoblast outgrowth occurs on Ln and its E8 fragment (long arm), but not on the E1’ fragment (cross region) (Figs. 1, 2 ). This outgrowth is inhibited by anti-E8, anti-Ln, and by the anti-β1 family antiserum anti-ECMR, but not by anti-αV or the function-perturbing GoH3 antibody that recognizes the α6/β1 integrin, a major Ln (E8) receptor. This suggests that trophoblast outgrowth on Ln or E8 is mediated by a different β1 integrin such as α3/β1. Early stages of trophoblast outgrowth (up to 48 hours) on Fn are inhibited by anti-Fn and by function-perturbing anti-αV antibodies, whereas at later times outgrowth becomes insensitive to anti-αV but remains sensitive to the anti-β1 family antiserum anti-ECMr, indicating that trophoblast cells modulate their interaction with Fn during outgrowth. Trophoblast outgrowth on vitronectin (Vn) is sensitive to anti-αV antibodies throughout the 5-day period examined.

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