Caveolin-3 associates with developing T-tubules during muscle differentiation.
Caveolae, flask-shaped invaginations of the plasma membrane, are particularly abundant in muscle cells. We have recently cloned a muscle-specific caveolin, termed caveolin-3, which is expressed in differentiated muscle cells. Specific antibodies to caveolin-3 were generated and used to characterize the distribution of caveolin-3 in adult and differentiating muscle. In fully differentiated skeletal muscle, caveolin-3 was shown to be associated exclusively with sarcolemmal caveolae. Localization of caveolin-3 during differentiation of primary cultured muscle cells and development of mouse skeletal muscle in vivo suggested that caveolin-3 is transiently associated with an internal membrane system. These elements were identified as developing transverse-(T)-tubules by double-labeling with antibodies to the alpha 1 subunit of the dihydropyridine receptor in C2C12 cells. Ultrastructural analysis of the caveolin-3-labeled elements showed an association of caveolin-3 with elaborate networks of interconnected caveolae, which penetrated the depths of the muscle fibers. These elements, which formed regular reticular structures, were shown to be surface-connected by labeling with cholera toxin conjugates. The results suggest that caveolin-3 transiently associates with T-tubules during development and may be involved in the early development of the T-tubule system in muscle.
Parton
R G
RG
Department of Physiology and Pharmacology, University of Queensland, Brisbane, Australia. R.Parton@mailbox.uq.oz.au
Way
M
M
Zorzi
N
N
Stang
E
E
D000595:Amino Acid Sequence; D000818:Animals; D051242:Caveolin 1; D051244:Caveolin 3; D022461:Caveolins; D002454:Cell Differentiation; D002478:Cells, Cultured; D002772:Cholera Toxin; D007425:Intracellular Membranes / Q000737:chemistry* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000032:analysis*; D051379:Mice; D008969:Molecular Sequence Data; D018485:Muscle Fibers, Skeletal / Q000737:chemistry / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000737:chemistry / Q000166:cytology* / Q000196:embryology; D009206:Myocardium / Q000737:chemistry; D012508:Sarcolemma / Q000737:chemistry
C495541:Cav1 protein, mouse; C495548:Cav3 protein, mouse; D051242:Caveolin 1; D051244:Caveolin 3; D022461:Caveolins; D008565:Membrane Proteins; D002772:Cholera Toxin