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Mov Disord. 2016 Nov;31(11):1694-1703. doi: 10.1002/mds.26738. Epub 2016 Aug 18.

Myoclonus dystonia and muscular dystrophy: ɛ-sarcoglycan is part of the dystrophin-associated protein complex in brain.

Author information

1
Division of Psychological Medicine and Clinical Neurosciences, MRC Centre for Neuropsychiatric Genetics and Genomics, Cardiff University, Cardiff, United Kingdom.
2
McColl-Lockwood Laboratory for Muscular Dystrophy Research, Carolinas Medical Center, Charlotte, North Carolina, USA.

Abstract

BACKGROUND:

Myoclonus-dystonia is a neurogenic movement disorder caused by mutations in the gene encoding ɛ-sarcoglycan. By contrast, mutations in the α-, β-, γ-, and δ-sarcoglycan genes cause limb girdle muscular dystrophies. The sarcoglycans are part of the dystrophin-associated protein complex in muscle that is disrupted in several types of muscular dystrophy. Intriguingly, patients with myoclonus-dystonia have no muscle pathology; conversely, limb-girdle muscular dystrophy patients have not been reported to have dystonia-associated features. To gain further insight into the molecular mechanisms underlying these differences, we searched for evidence of a sarcoglycan complex in the brain.

METHODS:

Immunoaffinity chromatography and mass spectrometry were used to purify ubiquitous and brain-specific ɛ-sarcoglycan directly from tissue. Cell models were used to determine the effect of mutations on the trafficking and assembly of the brain sarcoglycan complex.

RESULTS:

Ubiquitous and brain-specific ɛ-sarcoglycan isoforms copurify with β-, δ-, and ζ-sarcoglycan, β-dystroglycan, and dystrophin Dp71 from brain. Incorporation of a muscular dystrophy-associated β-sarcoglycan mutant into the brain sarcoglycan complex impairs the formation of the βδ-sarcoglycan core but fails to abrogate the association and membrane trafficking of ɛ- and ζ-sarcoglycan.

CONCLUSIONS:

ɛ-Sarcoglycan is part of the dystrophin-associated protein complex in brain. Partial preservation of ɛ- and ζ-sarcoglycan in brain may explain the absence of myoclonus dystonia-like features in muscular dystrophy patients. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

KEYWORDS:

DYT11; dystonia; sarcoglycan

PMID:
27535350
PMCID:
PMC5129563
DOI:
10.1002/mds.26738
[Indexed for MEDLINE]
Free PMC Article

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