| 1. |
- Borg, Kristian, et al.
(författare)
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Intragenic deletion of TRIM32 in compound heterozygotes with sarcotubular myopathy/LGMD2H
- 2009
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Ingår i: Human Mutation. - : Hindawi Limited. - 1059-7794 .- 1098-1004. ; 30:9, s. E831-E844
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Tidskriftsartikel (refereegranskat)abstract
- In 2005 the commonality of sarcotubular myopathy (STM) and limb girdle muscular dystrophy type 2H (LGMD2H) was demonstrated, as both are caused by the p D487N missense mutation in TRIM32 originally found in the Manitoba Hutterite population. Recently, three novel homozygous TRIM32 mutations have been described in LGMD patients. Here we describe a three generation Swedish family clinically presenting with limb girdle muscular weakness and histological features of a microvacuolar myopathy. The two index patients were compound heterozygotes for a frameshift mutation in TRIM32 (c.1560delC ) and a 30 kb intragenic deletion, encompassing parts of intron 1 and the entire exon 2 of TRIM32. In these patients, no full-length or truncated TRIM32 could be detected. Interestingly, heterozygous family members carrying only one mutation showed mild clinical symptoms and vacuolar changes in muscle. In our family, the phenotype encompasses additionally a mild demyelinating polyneuropathic syndrome. Thus STM and LGMD2H are the result of loss of function mutations that can be either deletions or missense mutations. (c) 2009 Wiley-Liss, Inc.
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| 2. |
- Fugier, Charlotte, et al.
(författare)
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Misregulated alternative splicing of BIN1 is associated with T tubule alterations and muscle weakness in myotonic dystrophy
- 2011
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Ingår i: Nature medicine. - : Springer Science and Business Media LLC. - 1546-170X .- 1078-8956. ; 17:6, s. 720-725
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Tidskriftsartikel (refereegranskat)abstract
- Myotonic dystrophy is the most common muscular dystrophy in adults and the first recognized example of an RNA-mediated disease. Congenital myotonic dystrophy (CDM1) and myotonic dystrophy of type 1 (DM1) or of type 2 (DM2) are caused by the expression of mutant RNAs containing expanded CUG or CCUG repeats, respectively. These mutant RNAs sequester the splicing regulator Muscleblind-like-1 (MBNL1), resulting in specific misregulation of the alternative splicing of other pre-mRNAs. We found that alternative splicing of the bridging integrator-1 (BIN1) pre-mRNA is altered in skeletal muscle samples of people with CDM1, DM1 and DM2. BIN1 is involved in tubular invaginations of membranes and is required for the biogenesis of muscle T tubules, which are specialized skeletal muscle membrane structures essential for excitation-contraction coupling. Mutations in the BIN1 gene cause centronuclear myopathy, which shares some histopathological features with myotonic dystrophy. We found that MBNL1 binds the BIN1 pre-mRNA and regulates its alternative splicing. BIN1 missplicing results in expression of an inactive form of BIN1 lacking phosphatidylinositol 5-phosphate-binding and membrane-tubulating activities. Consistent with a defect of BIN1, muscle T tubules are altered in people with myotonic dystrophy, and membrane structures are restored upon expression of the normal splicing form of BIN1 in muscle cells of such individuals. Finally, reproducing BIN1 splicing alteration in mice is sufficient to promote T tubule alterations and muscle weakness, a predominant feature of myotonic dystrophy.
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| 3. |
- Nilsson, Johanna, et al.
(författare)
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Polyglucosan body myopathy caused by defective ubiquitin ligase RBCK1.
- 2013
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Ingår i: Annals of neurology. - : Wiley. - 1531-8249 .- 0364-5134. ; 74:6, s. 914-919
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Tidskriftsartikel (refereegranskat)abstract
- Glycogen storage diseases are important causes of myopathy and cardiomyopathy. We describe ten patients from eight families with childhood or juvenile onset of myopathy, eight of whom also had rapidly progressive cardiomyopathy requiring heart transplant in four. The patients were homozygous or compound heterozygous for missense or truncating mutations in the ubiquitin ligase RBCK1 and had extensive polyglucosan accumulation in skeletal muscle and in the heart in cases of cardiomyopathy. We conclude that RBCK1 deficiency is a frequent cause of polyglucosan storage myopathy associated with progressive muscle weakness and cardiomyopathy. ANN NEUROL 2013. © 2013 American Neurological Association.
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| 4. |
- Rudnik, Jana, et al.
(författare)
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Differential expression of nitric oxide synthases (NOS 1-3) in human skeletal muscle following exercise countermeasure during 12 weeks of bed rest.
- 2004
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Ingår i: The F A S E B Journal. - 0892-6638. ; 18:11, s. 1228-1230
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Tidskriftsartikel (refereegranskat)abstract
- Nitric oxide (NO) generated from NO synthases mediates normal skeletal muscle functions. Biosynthesis of NO apparently is linked to muscle activity, but the distribution and expression of the three major NO synthase 1-3 isoforms under conditions of extended muscle disuse and exercise are still unclear. Our aim was to elucidate whether protein levels and the cellular or subcellular localization patterns of NO synthases underwent significant changes in a mixed fast/slow and slow type skeletal muscle after prolonged disuse in a long-term bed rest study, a useful experimental paradigm of simulated microgravity in ground-based space research. We examined whether resistance exercise performed regularly as a countermeasure to progressive atrophy within 12 wk of strict bed rest would support expression of one or more isoforms of NOS, thereby maintaining normal skeletal muscle functions during immobilization in clinical settings or in human spaceflight.
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