Limits...
A novel mutation in CLCN1 associated with feline myotonia congenita.

Gandolfi B, Daniel RJ, O'Brien DP, Guo LT, Youngs MD, Leach SB, Jones BR, Shelton GD, Lyons LA - PLoS ONE (2014)

Bottom Line: Studies in mice, dogs, humans and goats confirmed myotonia associated with functional defects in chloride channels and mutations in a skeletal muscle chloride channel (CLCN1).Muscle histopathology showed hypertrophy of all fiber types.In vitro translation of the mutated protein predicted a premature truncation and partial lack of the highly conserved CBS1 (cystathionine β-synthase) domain critical for ion transport activity and one dimerization domain pivotal in channel formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Medicine and Surgery, School of Veterinary Medicine, University of Missouri - Columbia, Columbia, Missouri, United States of America.

ABSTRACT
Myotonia congenita (MC) is a skeletal muscle channelopathy characterized by inability of the muscle to relax following voluntary contraction. Worldwide population prevalence in humans is 1:100,000. Studies in mice, dogs, humans and goats confirmed myotonia associated with functional defects in chloride channels and mutations in a skeletal muscle chloride channel (CLCN1). CLCN1 encodes for the most abundant chloride channel in the skeletal muscle cell membrane. Five random bred cats from Winnipeg, Canada with MC were examined. All cats had a protruding tongue, limited range of jaw motion and drooling with prominent neck and proximal limb musculature. All cats had blepharospasm upon palpebral reflex testing and a short-strided gait. Electromyograms demonstrated myotonic discharges at a mean frequency of 300 Hz resembling the sound of a 'swarm of bees'. Muscle histopathology showed hypertrophy of all fiber types. Direct sequencing of CLCN1 revealed a mutation disrupting a donor splice site downstream of exon 16 in only the affected cats. In vitro translation of the mutated protein predicted a premature truncation and partial lack of the highly conserved CBS1 (cystathionine β-synthase) domain critical for ion transport activity and one dimerization domain pivotal in channel formation. Genetic screening of the Winnipeg random bred population of the cats' origin identified carriers of the mutation. A genetic test for population screening is now available and carrier cats from the feral population can be identified.

Show MeSH

Related in: MedlinePlus

Antibody markers against RYR, DHRPα1 and CLCN1.To further investigate the subcellular localization of the chloride channels in myotonic cats, antibody markers for the sarcoplasmic reticulum (RYR; ryanodine receptor, green) and T-tubule system (DHRPα1, green) were co-stained with antibodies against CLCL1 (red) and compared to control muscle. The merge figures for both myotonic and control cats (yellow) show close proximity of CLC1 to the sarcoplasmic reticulum and T-tubule system. Bar  = 50 µm for all images.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4214686&req=5

pone-0109926-g008: Antibody markers against RYR, DHRPα1 and CLCN1.To further investigate the subcellular localization of the chloride channels in myotonic cats, antibody markers for the sarcoplasmic reticulum (RYR; ryanodine receptor, green) and T-tubule system (DHRPα1, green) were co-stained with antibodies against CLCL1 (red) and compared to control muscle. The merge figures for both myotonic and control cats (yellow) show close proximity of CLC1 to the sarcoplasmic reticulum and T-tubule system. Bar  = 50 µm for all images.

Mentions: Cryosections (8 µm) from the biceps femoris muscle of affected and control cats were incubated with rabbit polyclonal antibodies against the C-terminus and N-terminus of CLCN1 and co-stained with a monoclonal antibody against dystrophin (marker for the muscle sarcolemma). The sections were then processed by indirect immunofluorescence. Staining using both antibodies against CLCN1 was localized to the interior of the myofiber and was distinctly punctate in nature without co-localization with dystrophin to the muscle sarcolemma (Figure 7). To further investigate the subcellular localization of the chloride channels, antibody markers for the sarcoplasmic reticulum (ryanodine receptor) and T-tubule system (dihydropyridine receptor DHPRα1) were co-stained with both antibodies against CLCN1 and compared to control muscle. Staining strongly suggested either co-localization or a close association with the T-tubule system (Figure 8).


A novel mutation in CLCN1 associated with feline myotonia congenita.

Gandolfi B, Daniel RJ, O'Brien DP, Guo LT, Youngs MD, Leach SB, Jones BR, Shelton GD, Lyons LA - PLoS ONE (2014)

Antibody markers against RYR, DHRPα1 and CLCN1.To further investigate the subcellular localization of the chloride channels in myotonic cats, antibody markers for the sarcoplasmic reticulum (RYR; ryanodine receptor, green) and T-tubule system (DHRPα1, green) were co-stained with antibodies against CLCL1 (red) and compared to control muscle. The merge figures for both myotonic and control cats (yellow) show close proximity of CLC1 to the sarcoplasmic reticulum and T-tubule system. Bar  = 50 µm for all images.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4214686&req=5

pone-0109926-g008: Antibody markers against RYR, DHRPα1 and CLCN1.To further investigate the subcellular localization of the chloride channels in myotonic cats, antibody markers for the sarcoplasmic reticulum (RYR; ryanodine receptor, green) and T-tubule system (DHRPα1, green) were co-stained with antibodies against CLCL1 (red) and compared to control muscle. The merge figures for both myotonic and control cats (yellow) show close proximity of CLC1 to the sarcoplasmic reticulum and T-tubule system. Bar  = 50 µm for all images.
Mentions: Cryosections (8 µm) from the biceps femoris muscle of affected and control cats were incubated with rabbit polyclonal antibodies against the C-terminus and N-terminus of CLCN1 and co-stained with a monoclonal antibody against dystrophin (marker for the muscle sarcolemma). The sections were then processed by indirect immunofluorescence. Staining using both antibodies against CLCN1 was localized to the interior of the myofiber and was distinctly punctate in nature without co-localization with dystrophin to the muscle sarcolemma (Figure 7). To further investigate the subcellular localization of the chloride channels, antibody markers for the sarcoplasmic reticulum (ryanodine receptor) and T-tubule system (dihydropyridine receptor DHPRα1) were co-stained with both antibodies against CLCN1 and compared to control muscle. Staining strongly suggested either co-localization or a close association with the T-tubule system (Figure 8).

Bottom Line: Studies in mice, dogs, humans and goats confirmed myotonia associated with functional defects in chloride channels and mutations in a skeletal muscle chloride channel (CLCN1).Muscle histopathology showed hypertrophy of all fiber types.In vitro translation of the mutated protein predicted a premature truncation and partial lack of the highly conserved CBS1 (cystathionine β-synthase) domain critical for ion transport activity and one dimerization domain pivotal in channel formation.

View Article: PubMed Central - PubMed

Affiliation: Department of Veterinary Medicine and Surgery, School of Veterinary Medicine, University of Missouri - Columbia, Columbia, Missouri, United States of America.

ABSTRACT
Myotonia congenita (MC) is a skeletal muscle channelopathy characterized by inability of the muscle to relax following voluntary contraction. Worldwide population prevalence in humans is 1:100,000. Studies in mice, dogs, humans and goats confirmed myotonia associated with functional defects in chloride channels and mutations in a skeletal muscle chloride channel (CLCN1). CLCN1 encodes for the most abundant chloride channel in the skeletal muscle cell membrane. Five random bred cats from Winnipeg, Canada with MC were examined. All cats had a protruding tongue, limited range of jaw motion and drooling with prominent neck and proximal limb musculature. All cats had blepharospasm upon palpebral reflex testing and a short-strided gait. Electromyograms demonstrated myotonic discharges at a mean frequency of 300 Hz resembling the sound of a 'swarm of bees'. Muscle histopathology showed hypertrophy of all fiber types. Direct sequencing of CLCN1 revealed a mutation disrupting a donor splice site downstream of exon 16 in only the affected cats. In vitro translation of the mutated protein predicted a premature truncation and partial lack of the highly conserved CBS1 (cystathionine β-synthase) domain critical for ion transport activity and one dimerization domain pivotal in channel formation. Genetic screening of the Winnipeg random bred population of the cats' origin identified carriers of the mutation. A genetic test for population screening is now available and carrier cats from the feral population can be identified.

Show MeSH
Related in: MedlinePlus