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Protein 4.1R expression in normal and dystrophic skeletal muscle
François Delhommeau1, Nicole Dalla Venezia, Madeleine Morinière
1Inserm U473 & Service d'hématologie, hôpital de Bicêtre and faculté de médecine Paris-Sud, 63, rue Gabriel-Péri, 94270 Le Kremlin-Bicêtre cedex, France.
Comptes Rendus Biologies
|February 18, 2005
Summary
Protein 4.1R isoforms containing exon 17a are specific to muscle tissue and localize to myofibers. Their presence at the sarcolemma is linked to dystrophin in muscular dystrophy models.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Alternative splicing of 4.1R pre-mRNA generates diverse mRNA and protein isoforms.
- Specific isoforms containing exon 17a are exclusively found in muscle tissues.
Purpose of the Study:
- To investigate the localization and regulation of 4.1R isoforms in muscle.
- To examine the relationship between 4.1R and dystrophin in muscle pathology.
Main Methods:
- Immunohistochemistry to detect 4.1R epitopes in muscle.
- Analysis of alternative splicing during muscle differentiation.
- Western blot to characterize 4.1R protein isoforms.
Main Results:
- 4.1R isoforms with exon 17a are preferentially located in the myoplasm of fast myofibers.
- 4.1R epitopes are present at the sarcolemma of normal muscle but absent in Duchenne muscular dystrophy (DMD) muscle.
- Alternative splicing of exons 16 and 17a is asynchronous during muscle differentiation.
- A specific 96/98-kDa 4.1R protein doublet containing exons 16-17a is found exclusively in differentiated muscle.
Conclusions:
- Muscle-specific 4.1R isoforms are regulated during differentiation and localized within myofibers.
- The association of 4.1R with the sarcolemma is dependent on dystrophin, suggesting a role in muscle integrity.