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J Cell Biol. 2013 Feb 18;200(4):523-36. doi: 10.1083/jcb.201205118.

Obscurin is required for ankyrinB-dependent dystrophin localization and sarcolemma integrity.

Author information

1
Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, 53100 Siena, Italy.

Abstract

Obscurin is a large myofibrillar protein that contains several interacting modules, one of which mediates binding to muscle-specific ankyrins. Interaction between obscurin and the muscle-specific ankyrin sAnk1.5 regulates the organization of the sarcoplasmic reticulum in striated muscles. Additional muscle-specific ankyrin isoforms, ankB and ankG, are localized at the subsarcolemma level, at which they contribute to the organization of dystrophin and β-dystroglycan at costameres. In this paper, we report that in mice deficient for obscurin, ankB was displaced from its localization at the M band, whereas localization of ankG at the Z disk was not affected. In obscurin KO mice, localization at costameres of dystrophin, but not of β-dystroglycan, was altered, and the subsarcolemma microtubule cytoskeleton was disrupted. In addition, these mutant mice displayed marked sarcolemmal fragility and reduced muscle exercise tolerance. Altogether, the results support a model in which obscurin, by targeting ankB at the M band, contributes to the organization of subsarcolemma microtubules, localization of dystrophin at costameres, and maintenance of sarcolemmal integrity.

PMID:
23420875
PMCID:
PMC3575540
DOI:
10.1083/jcb.201205118
[Indexed for MEDLINE]
Free PMC Article

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