Alterations of Excitation-Contraction Coupling and Excitation Coupled Ca2+ Entry in Human Myotubes Carrying CAV3 Mutations Linked to Rippling Muscle Disease

作者：Ullrich Nina D; Fischer Dirk; Kornblum Cornelia; Walter Maggie C; Niggli Ernst; Zorzato Francesco; Treves Susan^*

来源：Human Mutation, 2011, 32(3): 309-317.

DOI：10.1002/humu.21431

• caveolin-3
• CAV3
• rippling muscle disease
• excitation-contraction coupling
• excitation coupled Ca2+ entry
• Ca2+ homeostasis
• TIRF microscopy

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 Ca2+ homeostasis. In the present study we examined Ca2+ 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 [Ca2+](i) and 4-chloro-m-cresol-induced Ca2+ release but reduced KCl-induced Ca2+ influx. Detailed analysis of the voltage-dependence of Ca2+ transients revealed a significant shift of Ca2+ 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. Hum Mutat 32:309-317, 2011.

• 出版日期2011-3