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The calcium channel α2/δ1 subunit is involved in extracellular signalling
Author(s) -
García Kelly,
Nabhani Thomas,
García Jesús
Publication year - 2008
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2007.147959
Subject(s) - protein subunit , myogenesis , myocyte , extracellular , microbiology and biotechnology , skeletal muscle , calcium channel , biology , ryanodine receptor , chemistry , intracellular , calcium , biochemistry , anatomy , organic chemistry , gene
The α2/δ1 subunit forms part of the dihydropyridine receptor, an essential protein complex for excitation–contraction (EC) coupling in skeletal muscle. Because of the lack of a viable knock‐out animal, little is known regarding the role of the α2/δ1 subunit in EC coupling or in other cell functions. Interestingly, the α2/δ1 appears before the α1 subunit in development and contains extracellular conserved domains known to be important in cell signalling and inter‐protein interactions. These facts raise the possibility that the α2/δ1 subunit performs vital functions not associated with EC coupling. Here, we tested the hypothesis that the α2/δ1 subunit is important for interactions of muscle cells with their environment. Using confocal microscopy, we followed the immunolocalization of α2/δ1 and α1 subunits with age. We found that in 2‐day‐old myotubes, the α2/δ1 subunit concentrated towards the ends of the cells, while the α1 subunit clustered near the centre. As myotubes aged (6–12 days), the α2/δ1 became evenly distributed along the myotubes and co‐localized with α1. When the expression of α2/δ1 was blocked with siRNA, migration, attachment and spreading of myoblasts were impaired while the L‐type calcium current remained unaffected. The results suggest a previously unidentified role of the α2/δ1 subunit in skeletal muscle and support the involvement of this protein in extracellular signalling. This new role of the α2/δ1 subunit may be crucial for muscle development, muscle repair and at times in which myoblast attachment and migration are fundamental.