Excitation–contraction coupling (ECC) is the physiological mechanism whereby an electrical signal detected by the dihydropyridine receptor, is converted into an increase in [Ca2+], via activation of ryanodine receptors (RyRs). Mutations in RYR1, the gene encoding RyR1, are the underlying cause of various congenital myopathies including central core disease, multiminicore disease (MmD), some forms of centronuclear myopathy (CNM) and congenital fibre-type disproportion. Interestingly, patients with recessive, but not dominant, RYR1 mutations show a significant reduction in RyR protein in muscle biopsies as well as ophthalmoplegia. This specific involvement of the extraocular muscles (EOMs) indicates that this group of muscles may express different amounts of proteins involved in ECC compared with limb muscles. In the present paper, we report that this is indeed the case; in particular the transcripts encoding RyR3, cardiac calsequestrin (CSQ2) and the α1 subunit of the cardiac dihydropyridine receptor are up-regulated by at least 100-fold, whereas excitation-coupled Ca2+ entry is 3-fold higher. These findings support the hypothesis that EOMs have a unique mode of calcium handling.
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Research Article|
February 06 2015
Characterization of excitation–contraction coupling components in human extraocular muscles
Marijana Sekulic-Jablanovic;
Marijana Sekulic-Jablanovic
*Departments of Anesthesia and Biomedizin, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland
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Anja Palmowski-Wolfe;
Anja Palmowski-Wolfe
†Eye Hospital, Basel University Hospital, Mittlere Strasse 91, 4031Basel, Switzerland
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Francesco Zorzato;
Francesco Zorzato
*Departments of Anesthesia and Biomedizin, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland
‡Department of Life Sciences and Biotechnology, General Pathology section, University of Ferrara, Via Borsari 46, 44100 Ferrara, Italy
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Susan Treves
Susan Treves
1
*Departments of Anesthesia and Biomedizin, Basel University Hospital, Hebelstrasse 20, 4031 Basel, Switzerland
‡Department of Life Sciences and Biotechnology, General Pathology section, University of Ferrara, Via Borsari 46, 44100 Ferrara, Italy
1To whom correspondence should be addressed (email susan.treves@unibas.ch).
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Publisher: Portland Press Ltd
Received:
July 29 2014
Revision Received:
October 09 2014
Accepted:
November 11 2014
Accepted Manuscript online:
November 11 2014
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2015 Biochemical Society
2015
Biochem J (2015) 466 (1): 29–36.
Article history
Received:
July 29 2014
Revision Received:
October 09 2014
Accepted:
November 11 2014
Accepted Manuscript online:
November 11 2014
Citation
Marijana Sekulic-Jablanovic, Anja Palmowski-Wolfe, Francesco Zorzato, Susan Treves; Characterization of excitation–contraction coupling components in human extraocular muscles. Biochem J 15 February 2015; 466 (1): 29–36. doi: https://doi.org/10.1042/BJ20140970
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