Normal calcium homeostasis in dystrophin-expressing facioscapulohumeral muscular dystrophy myotubes.
The aim of this study was to provide a set of data on mechanisms involved in the calcium homeostasis of facioscapulohumeral muscular dystrophy (FSHD) co-cultured myotubes. In fact, abnormal regulation of calcium have been shown in deficient dystrophin cells like Duchenne muscular dystrophy (DMD) cells, and it seemed interesting to study the calcium regulation in a pathologic cellular model which express dystrophin. T- and L-type calcium currents and contractile responses induced by membrane depolarisations as well as intracellular calcium transients induced by three kinds of stimulus (superfusions of acetylcholine, high K+ or caffeine containing media) were recorded by means of whole-cell patch-clamp and ratiometric cytofluorimetry in co-cultured FSHD myotubes which presented a sarcolemmal localisation of dystrophin. As judged from calcium currents properties, voltage-dependency of contractile responses or amplitude of evoked calcium transients, no clear difference in the calcium handling or calcium signalling was observed between this type of cell and the control cells, at least with the means and the conditions used in the present study. Since FSHD cells, contrary to DMD (Duchenne muscular dystrophy) cells, seemed to display both dystrophin expression and unaltered calcium regulation, the FSHD co-cultured cells appeared as a useful model of dystrophin-expressing pathological muscle cells to further investigate the link between dystrophin expression and intracellular calcium level regulation.
Vandebrouck
Clarisse
C
Laboratoire de Biomembranes et Signalisation Cellulaire, UMR CNRS/Université de Poitiers 6558, F-86022 Poitiers Cedex, France. clarisse.vandebrouck@fymu.ucl.ac.be
Imbert
Nathalie
N
Constantin
Bruno
B
Duport
Gérard
G
Raymond
Guy
G
Cognard
Christian
C
D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology; D002478:Cells, Cultured; D018920:Coculture Techniques; D016189:Dystrophin / Q000032:analysis / Q000378:metabolism*; D004594:Electrophysiology; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology; D020391:Muscular Dystrophy, Facioscapulohumeral / Q000378:metabolism*
D020746:Calcium Channels, L-Type; D020747:Calcium Channels, T-Type; D016189:Dystrophin; D002118:Calcium