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The absence of dysferlin induces the expression of functional connexin-based hemichannels in human myotubes
- Source :
- BMC Cell Biology, BMC Cell Biology, BioMed Central, 2016, 17 (S1), pp.15. ⟨10.1186/s12860-016-0096-6⟩, Bmc Cell Biology, Artículos CONICYT, CONICYT Chile, instacron:CONICYT, BMC Cell Biology, 2016, 17 (S1), pp.15. ⟨10.1186/s12860-016-0096-6⟩
- Publication Year :
- 2016
- Publisher :
- BioMed Central, 2016.
-
Abstract
- International audience; Background: Mutations in the gene encoding for dysferlin cause recessive autosomal muscular dystrophies called dysferlinopathies. These mutations induce several alterations in skeletal muscles, including, inflammation, increased membrane permeability and cell death. Despite the fact that the etiology of dysferlinopathies is known, the mechanism that explains the aforementioned alterations is still elusive. Therefore, we have now evaluated the potential involvement of connexin based hemichannels in the pathophysiology of dysferlinopathies. Results: Human deltoid muscle biopsies of 5 Chilean dysferlinopathy patients exhibited the presence of muscular connexins (Cx40.1, Cx43 and Cx45). The presence of these connexins was also observed in human myotubes derived from immortalized myoblasts derived from other patients with mutated forms of dysferlin. In addition to the aforementioned connexins, these myotubes expressed functional connexin based hemichannels, evaluated by ethidium uptake assays, as opposed to myotubes obtained from a normal human muscle cell line, RCMH. This response was reproduced in a knock-down model of dysferlin, by treating RCMH cell line with small hairpin RNA specific for dysferlin (RCMH-sh Dysferlin). Also, the presence of P2X 7 receptor and the transient receptor potential channel, TRPV2, another Ca 2+ permeable channels, was detected in the myotubes expressing mutated dysferlin, and an elevated resting intracellular Ca 2+ level was found in the latter myotubes, which was in turn reduced to control levels in the presence of the molecule D4, a selective Cx HCs inhibitor. Conclusions: The data suggests that dysferlin deficiency, caused by mutation or downregulation of dysferlin, promotes the expression of Cx HCs. Then, the de novo expression Cx HC causes a dysregulation of intracellular free Ca 2+ levels, which could underlie muscular damage associated to dysferlin mutations. This mechanism could constitute a potential therapeutical target in dysferlinopathies.ResultsHuman deltoid muscle biopsies of 5 Chilean dysferlinopathy patients exhibited the presence of muscular connexins (Cx40.1, Cx43 and Cx45). The presence of these connexins was also observed in human myotubes derived from immortalized myoblasts derived from other patients with mutated forms of dysferlin. In addition to the aforementioned connexins, these myotubes expressed functional connexin based hemichannels, evaluated by ethidium uptake assays, as opposed to myotubes obtained from a normal human muscle cell line, RCMH. This response was reproduced in a knock-down model of dysferlin, by treating RCMH cell line with small hairpin RNA specific for dysferlin (RCMH-sh Dysferlin). Also, the presence of P2X7 receptor and the transient receptor potential channel, TRPV2, another Ca2+ permeable channels, was detected in the myotubes expressing mutated dysferlin, and an elevated resting intracellular Ca2+ level was found in the latter myotubes, which was in turn reduced to control levels in the presence of the molecule D4, a selective Cx HCs inhibitor.ConclusionsThe data suggests that dysferlin deficiency, caused by mutation or downregulation of dysferlin, promotes the expression of Cx HCs. Then, the de novo expression Cx HC causes a dysregulation of intracellular free Ca2+ levels, which could underlie muscular damage associated to dysferlin mutations. This mechanism could constitute a potential therapeutical target in dysferlinopathies.
- Subjects :
- 0301 basic medicine
Dysferlinopathy
Membrane permeability
Biopsy
Muscle Fibers, Skeletal
Intracellular Space
Connexin
Muscle Proteins
TRPV Cation Channels
medicine.disease_cause
Connexins
Cell Line
Dysferlin
03 medical and health sciences
Sarcolemma
[SDV.BDD] Life Sciences [q-bio]/Development Biology
medicine
Myocyte
Humans
Calcium Signaling
[SDV.BDD]Life Sciences [q-bio]/Development Biology
Mutation
biology
Myogenesis
Research
Membrane Proteins
Cell Biology
medicine.disease
Cell biology
030104 developmental biology
Muscular Dystrophies, Limb-Girdle
biology.protein
Calcium
Receptors, Purinergic P2X7
Intracellular
Subjects
Details
- Language :
- English
- ISSN :
- 14712121
- Volume :
- 17
- Issue :
- Suppl 1
- Database :
- OpenAIRE
- Journal :
- BMC Cell Biology
- Accession number :
- edsair.doi.dedup.....a0f62ab177ab436c6d7fbe955fb5f2f4
- Full Text :
- https://doi.org/10.1186/s12860-016-0096-6⟩