Alterations of excitation-contraction coupling and excitation coupled Ca(2+) entry in human myotubes carrying CAV3 mutations linked to rippling muscle.

Abstract

Rippling muscle disease is caused by mutations in the gene encoding caveolin-3 (CAV3), the muscle-specific isoform of the scaffolding protein caveolin, a protein involved in the formation of caveolae. In healthy muscle, caveolin-3 is responsible for the formation of caveolae, which are highly organized sarcolemmal clusters influencing early muscle differentiation, signalling and Ca(2+) homeostasis. In the present study we examined Ca(2+) homeostasis and excitation-contraction (E-C) coupling in cultured myotubes derived from two patients with Rippling muscle disease with severe reduction in caveolin-3 expression; one patient harboured the heterozygous c.84C>A mutation while the other patient harbored a homozygous splice-site mutation (c.102+ 2T>C) affecting the splice donor site of intron 1 of the CAV3 gene. Our results show that cells from control and rippling muscle disease patients had similar resting [Ca(2+) ](i) and 4-chloro-m-cresol-induced Ca(2+) release but reduced KCl-induced Ca(2+) influx. Detailed analysis of the voltage-dependence of Ca(2+) transients revealed a significant shift of Ca(2+) release activation to higher depolarization levels in CAV3 mutated cells. High resolution immunofluorescence analysis by Total Internal Fluorescence microscopy supports the hypothesis that loss of caveolin-3 leads to microscopic disarrays in the colocalization of the voltage-sensing dihydropyridine receptor and the ryanodine receptor, thereby reducing the efficiency of excitation-contraction coupling.

• Authors: Nina D Ullrich, Dirk Fischer, Cornelia Kornblum, Maggie C Walter, Ernst Niggli, Francesco Zorzato, Susan Treves
• Journal: Human mutation (Hum Mutat) Vol. 32 Issue 3 Pg. 309-17 (Mar 2011) ISSN: 1098-1004 [Electronic] United States
• PMID: 21294223 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2011 Wiley-Liss, Inc.

Chemical References

• CAV3 protein, human
• Calcium Channels
• Calcium Channels, L-Type
• Caveolin 3
• Cresols
• Ryanodine Receptor Calcium Release Channel
• chlorocresol
• Potassium Chloride
• Calcium

Topics

• Calcium (analysis, metabolism)
• Calcium Channels (genetics, metabolism)
• Calcium Channels, L-Type (metabolism)
• Caveolin 3 (genetics, metabolism)
• Cells, Cultured
• Cresols (pharmacology)
• Excitation Contraction Coupling
• Humans
• Muscle Contraction (genetics, physiology)
• Muscle Development (genetics)
• Muscle Fibers, Skeletal (metabolism)
• Muscle, Skeletal (embryology, metabolism)
• Muscular Diseases (genetics, metabolism)
• Potassium Chloride (pharmacology)
• Ryanodine Receptor Calcium Release Channel (metabolism)