Extrasynaptic location of laminin beta 2 chain in developing and adult human skeletal muscle.
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.
Wewer
U M
UM
Institute of Molecular Pathology, University of Copenhagen, Denmark.
Thornell
L E
LE
Loechel
F
F
Zhang
X
X
Durkin
M E
ME
Amano
S
S
Burgeson
R E
RE
Engvall
E
E
Albrechtsen
R
R
Virtanen
I
I
D000328:Adult; D000911:Antibodies, Monoclonal; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007797:Laminin / Q000032:analysis* / Q000276:immunology; D018482:Muscle, Skeletal / Q000166:cytology / Q000196:embryology / Q000294:innervation / Q000378:metabolism*; D009136:Muscular Dystrophies / Q000378:metabolism / Q000473:pathology; D009469:Neuromuscular Junction / Q000378:metabolism; D011247:Pregnancy; D012508:Sarcolemma / Q000378:metabolism*; D014162:Transfection
D000911:Antibodies, Monoclonal; D007797:Laminin