We used immunofluorescence techniques and confocal imaging to study the organization of the membrane skeleton of skeletal muscle fibers of mdx mice, which lack dystrophin. β-Spectrin is normally found at the sarcolemma in costameres, a rectilinear array of longitudinal strands and elements overlying Z and M lines. However, in the skeletal muscle of mdx mice, β-spectrin tends to be absent from the sarcolemma over M lines and the longitudinal strands may be disrupted or missing. Other proteins of the membrane and associated cytoskeleton, including syntrophin, β-dystroglycan, vinculin, and Na,K-ATPase are also concentrated in costameres, in control myofibers, and mdx muscle. They also distribute into the same altered sarcolemmal arrays that contain β-spectrin. Utrophin, which is expressed in mdx muscle, also codistributes with β-spectrin at the mutant sarcolemma. By contrast, the distribution of structural and intracellular membrane proteins, including α-actinin, the Ca-ATPase and dihydropyridine receptors, is not affected, even at sites close to the sarcolemma. Our results suggest that in myofibers of the mdx mouse, the membrane- associated cytoskeleton, but not the nearby myoplasm, undergoes widespread coordinated changes in organization. These changes may contribute to the fragility of the sarcolemma of dystrophic muscle.
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22 March 1999
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March 22 1999
Extensive but Coordinated Reorganization of the Membrane Skeleton in Myofibers of Dystrophic (mdx) Mice
McRae W. Williams,
McRae W. Williams
Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201
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Robert J. Bloch
Robert J. Bloch
Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201
Search for other works by this author on:
McRae W. Williams
Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201
Robert J. Bloch
Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland 21201
Address correspondence to Robert J. Bloch, 660 W. Redwood St., Baltimore, MD 21201. Tel. and Fax: (410) 706-8341. E-mail: [email protected]
This paper is dedicated to Guido Guidotti on his 65th birthday.
Our research has been supported by grants to R.J. Bloch from the National Institutes of Health (NS 17282) and from the Muscular Dystrophy Association.
Received:
November 23 1998
Revision Received:
February 09 1999
Online ISSN: 1540-8140
Print ISSN: 0021-9525
1999
J Cell Biol (1999) 144 (6): 1259–1270.
Article history
Received:
November 23 1998
Revision Received:
February 09 1999
Citation
McRae W. Williams, Robert J. Bloch; Extensive but Coordinated Reorganization of the Membrane Skeleton in Myofibers of Dystrophic (mdx) Mice . J Cell Biol 22 March 1999; 144 (6): 1259–1270. doi: https://doi.org/10.1083/jcb.144.6.1259
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