Multidisciplinary study of a new ClC-1 mutation causing myotonia congenita: a paradigm to understand and treat ion channelopathies.
Myotonia congenita is an inherited disease that is characterized by impaired muscle relaxation after contraction caused by loss-of-function mutations in the skeletal muscle ClC-1 channel. We report a novel ClC-1 mutation, T335N, that is associated with a mild phenotype in 1 patient, located in the extracellular I-J loop. The purpose of this study was to provide a solid correlation between T335N dysfunction and clinical symptoms in the affected patient as well as to offer hints for drug development. Our multidisciplinary approach includes patch-clamp electrophysiology on T335N and ClC-1 wild-type channels expressed in tsA201 cells, Western blot and quantitative PCR analyses on muscle biopsies from patient and unaffected individuals, and molecular dynamics simulations using a homology model of the ClC-1 dimer. T335N channels display reduced chloride currents as a result of gating alterations rather than altered surface expression. Molecular dynamics simulations suggest that the I-J loop might be involved in conformational changes that occur at the dimer interface, thus affecting gating. Finally, the gene expression profile of T335N carrier showed a diverse expression of K+channel genes, compared with control individuals, as potentially contributing to the phenotype. This experimental paradigm satisfactorily explained myotonia in the patient. Furthermore, it could be relevant to the study and therapy of any channelopathy.-Imbrici, P., Altamura, C., Camerino, G. M., Mangiatordi, G. F., Conte, E., Maggi, L., Brugnoni, R., Musaraj, K., Caloiero, R., Alberga, D., Marsano, R. M., Ricci, G., Siciliano, G., Nicolotti, O., Mora, M., Bernasconi, P., Desaphy, J.-F., Mantegazza, R., Camerino, D. C. Multidisciplinary study of a new ClC-1 mutation causing myotonia congenita: a paradigm to understand and treat ion channelopathies.
Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy; paola.imbrici@uniba.
Paola
P
Imbrici
Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy.
Concetta
C
Altamura
Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy.
Giulia Maria
GM
Camerino
Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy.
Giuseppe Felice
GF
Mangiatordi
Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy.
Elena
E
Conte
Division of Neurology, Neuroimmunology and Neuromuscular Diseases Unit, Istituti di Ricovero e Cura a Carattere Scientifico Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy.
Lorenzo
L
Maggi
Division of Neurology, Neuroimmunology and Neuromuscular Diseases Unit, Istituti di Ricovero e Cura a Carattere Scientifico Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy.
Raffaella
R
Brugnoni
Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy.
Kejla
K
Musaraj
Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy.
Roberta
R
Caloiero
Department of Physics "M. Merlin," Istituto Nazionale di Fisica Nucleare and Centro di Tecnologie Innovative per la Rilevazione e l'Elaborazione del Segnale, University of Bari "Aldo Moro," Bari, Italy.
Domenico
D
Alberga
Department of Biology, University of Bari "Aldo Moro," Bari, Italy.
Renè Massimiliano
RM
Marsano
Department of Clinical and Experimental Medicine, Section of Neurology, University of Pisa, Pisa, Italy.
Giulia
G
Ricci
Department of Clinical and Experimental Medicine, Section of Neurology, University of Pisa, Pisa, Italy.
Gabriele
G
Siciliano
Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy.
Orazio
O
Nicolotti
Division of Neurology, Neuroimmunology and Neuromuscular Diseases Unit, Istituti di Ricovero e Cura a Carattere Scientifico Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy.
Marina
M
Mora
Division of Neurology, Neuroimmunology and Neuromuscular Diseases Unit, Istituti di Ricovero e Cura a Carattere Scientifico Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy.
Pia
P
Bernasconi
Department of Biomedical Sciences and Human Oncology, University of Bari "Aldo Moro," Bari, Italy.
Jean-Francois
JF
Desaphy
Division of Neurology, Neuroimmunology and Neuromuscular Diseases Unit, Istituti di Ricovero e Cura a Carattere Scientifico Fondazione Istituto Neurologico "Carlo Besta," Milan, Italy.
Renato
R
Mantegazza
Department of Pharmacy, Drug Sciences, University of Bari "Aldo Moro," Bari, Italy.
Diana Conte
DC
Camerino
D053447:Channelopathies / Q000378:metabolism*; D018118:Chloride Channels / Q000235:genetics* / Q000378:metabolism*; D055724:Electrophysiological Phenomena / Q000235:genetics*; D006801:Humans; D015640:Ion Channel Gating / Q000235:genetics / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D009224:Myotonia Congenita / Q000378:metabolism*; D018408:Patch-Clamp Techniques / Q000379:methods; D010641:Phenotype
C086321:CLC-1 channel; D018118:Chloride Channels
chloride channel; gene expression; molecular dynamics; patch-clamp; skeletal muscle