Alteration of Sarcoplasmic Reticulum Ca2+ Release in Skeletal Muscle from Calpain 3-Deficient Mice
Mutations of Ca2+-activated proteases (calpains) cause muscular dystrophies. Nevertheless, the specific role of calpains in Ca2+ signalling during the onset of dystrophies remains unclear. We investigated Ca2+ handling in skeletal cells from calpain 3-deficient mice. [Ca2+]i responses to caffeine, a...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Hindawi Limited
2009-01-01
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| Series: | International Journal of Cell Biology |
| Online Access: | http://dx.doi.org/10.1155/2009/340346 |
| Summary: | Mutations of Ca2+-activated proteases (calpains) cause muscular dystrophies. Nevertheless, the specific role of calpains in Ca2+ signalling during the onset of dystrophies remains unclear. We investigated Ca2+ handling in skeletal cells from calpain 3-deficient mice. [Ca2+]i responses to caffeine, a ryanodine receptor (RyR) agonist, were decreased in −/− myotubes and absent in −/− myoblasts. The −/− myotubes displayed smaller amplitudes of the Ca2+ transients induced by cyclopiazonic acid in comparison to wild type cells. Inhibition of L-type Ca2+ channels (LCC) suppressed the caffeine-induced [Ca2+]i responses in −/− myotubes. Hence, the absence of calpain 3 modifies the sarcoplasmic reticulum (SR) Ca2+ release, by a decrease of the SR content, an impairment of RyR signalling, and an increase of LCC activity. We propose that calpain 3-dependent proteolysis plays a role in activating support proteins of intracellular Ca2+ signalling at a stage of cellular differentiation which is crucial for skeletal muscle regeneration. |
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| ISSN: | 1687-8876 1687-8884 |