Extrasynaptic location of laminin beta 2 chain in developing and adult human skeletal muscle

• Published in: The American journal of pathology Vol. 151; no. 2; pp. 621 - 631
• Main Authors: Wewer, UM, Thornell, LE, Loechel, F, Zhang, X, Durkin, ME, Amano, S, Burgeson, RE, Engvall, E, Albrechtsen, R, Virtanen, I
• Format: Journal Article
• Language: English
• Published: United States ASIP 01-08-1997
• Subjects: Adult; Antibodies, Monoclonal; Female; Humans; Immunohistochemistry; Laminin - analysis; Laminin - immunology; Muscle, Skeletal - cytology; Muscle, Skeletal - embryology; Muscle, Skeletal - innervation; Muscle, Skeletal - metabolism; Muscular Dystrophies - metabolism; Muscular Dystrophies - pathology; Neuromuscular Junction - metabolism; Pregnancy; Sarcolemma - metabolism; Transfection
• ISSN: 0002-9440; 1525-2191

We have investigated the distribution of the laminin beta 2 chain (previously s-laminin) in human fetal and adult skeletal muscle and compared it to the distribution of laminin beta 1. Immunoblotting and transfection assays were used to characterize a panel of monoclonal and polyclonal antibodies to the laminin beta 2 chain. We found that laminin beta 1 chain was detected at all times during development from 10 weeks of gestation. Laminin beta 2 chain was first detected in 15 to 22-week-old fetal skeletal muscle as distinct focal immunoreactivity in the sarcolemmal basement membrane area of some myofibers. In the adult skeletal muscle, laminin beta 2 chain immunoreactivity was found along the entire perimeter of each of the individual myofibers in a large series of different muscles studied. Laminin beta 2 chain was similarly found in the skeletal muscle basement membranes in patients with Duchenne and Becker muscular dystrophy. Immunoaffinity chromatography of muscle extracts with a monoclonal antibody to the laminin alpha 2 chain followed by immunoblotting with various antibodies to the beta 2 chain demonstrated the presence of the laminin-4 (alpha 2-beta 2-gamma 1) isoform. Together the present results demonstrate a prominent extrasynaptic localization of laminin beta 2 in the human muscle, suggesting that it may have an important function in the sarcolemmal basement membrane.