Light-microscopic study of the beta 1 integrin subunit in human skeletal muscle.
The beta 1 integrin subunit is identical with the CD29 antigen, which is found at the surface of leukocytes. Integrins are involved in cell-cell and cell-matrix adhesion, mediate neuronal attachment and neurite outgrowth in response to extracellular matrix proteins in cell culture systems. A few analyses of beta 1 integrin subunit have been done on developing and regenerating skeletal muscle in animals; but cell culture systems and animal models differ in some respects from human skeletal muscle in situ. The expression of a beta 1 integrin subunit variant in human skeletal muscle was reported merely by Western blot analysis. Our present study, performed with immunohistochemical procedures, attempts to demonstrate the expression of the beta 1 integrin subunit in developing, normal adult, and diseased human skeletal muscles. The results demonstrated that the beta 1 integrin subunit is expressed in developing, normal adult, regenerating, and denervated human skeletal muscle. In developing muscle, the beta 1 integrin subunit was observed in muscle cells at least from 12 to 16 weeks of gestation. In muscular dystrophy and inflammatory myopathy the beta 1 integrin subunit staining occurs in basophilic muscle fibers. Furthermore, the beta 1 integrin subunit is expressed in mature fast twitch type 2 fibers, and in denervated myocytes in neurogenic muscular atrophy. On serial sections, the beta 1 integrin subunit, N-CAM (neural cell adhesion molecule) and vimentin are expressed in identical muscle fibers. However, in mature fast twitch type 2 fibers the beta 1 integrin subunit is expressed exclusively and in neurogenic muscular atrophy vimentin expression is weak. In conclusion, the beta 1 integrin subunit, in human skeletal muscles, probably plays a role in the growth morphology and innervation of developing, regenerating, and denervated myocytes. Furthermore, the observation that the beta 1 integrin subunit is enriched in mature fast twitch type 2 fibers indicates that the beta 1 integrin subunits may play a role in transducing mechanical forces to extracellular matrix proteins.
Heub
D
D
Department of Neurology, Friedrich Alexander University of Erlangen-Nürnberg, Germany.
Neundörfer
B
B
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D001706:Biopsy; D002648:Child; D005314:Embryonic and Fetal Development / Q000502:physiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D019012:Integrin beta1 / Q000032:analysis*; D008297:Male; D008853:Microscopy / Q000379:methods*; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000737:chemistry* / Q000196:embryology / Q000473:pathology; D009133:Muscular Atrophy / Q000378:metabolism / Q000473:pathology; D009135:Muscular Diseases / Q000378:metabolism / Q000473:pathology; D009136:Muscular Dystrophies / Q000378:metabolism / Q000473:pathology; D019006:Neural Cell Adhesion Molecules / Q000032:analysis; D012038:Regeneration / Q000502:physiology; D014746:Vimentin / Q000032:analysis*
D015415:Biomarkers; D019012:Integrin beta1; D019006:Neural Cell Adhesion Molecules; D014746:Vimentin