Novel sarco(endo)plasmic reticulum proteins and calcium homeostasis in striated muscles.

he impact of calcium signaling on many cellular functions is reflected by the tight regulation of the intracellular Ca(2+) concentration that is ensured by diverse pumps, channels, transporters and Ca(2+) binding proteins. In this review, we present recently identified novel sarco(endo)plasmic reticulum proteins that may have a potential involvement in the regulation of Ca(2+) homeostasis in striated muscles

Ryanodine receptor 1 mutations, dysregulation of calcium homeostasis and neuromuscular disorders

The skeletal muscle ryanodine receptor is an intracellular calcium release channel which plays a central role in excitation contraction coupling. At least 80 mutations have been identified in the gene encoding the skeletal muscle ryanodine receptor and linked to several neuromuscular disorders, whose common feature appears to be a dysregulation of calcium homeostasis. A decade of research into the functional consequences of how these mutations affect the functional properties of the ryanodine receptor and their impact on disease, have significantly advanced our understanding of Malignant Hyperthermia, Central Core Disease and Multiminicore Disease. This review gives an overview of the important findings in the field of calcium homeostasis in skeletal muscle and describes how mutations in the ryanodine receptor gene might affect the function of this intracellular calcium release channel and lead to neuromuscular disorders

Ryanodine receptor 1 mutations, dysregulation of calcium homeostasis and neuromuscular disorders.

The skeletal muscle ryanodine receptor is an intracellular calcium release channel which plays a central role in excitation contraction coupling. At least 80 mutations have been identified in the gene encoding the skeletal muscle ryanodine receptor and linked to several neuromuscular disorders, whose common feature appears to be a dysregulation of calcium homeostasis. A decade of research into the functional consequences of how these mutations affect the functional properties of the ryanodine receptor and their impact on disease, have significantly advanced our understanding of Malignant Hyperthermia, Central Core Disease and Multiminicore Disease. This review gives an overview of the important findings in the field of calcium homeostasis in skeletal muscle and describes how mutations in the ryanodine receptor gene might affect the function of this intracellular calcium release channel and lead to neuromuscular disorder

Increased Ca2+ storage capacity of the skeletal muscle sarcoplasmic reticulum of transgenic mice over-expressing membrane bound calcium binding protein junctate

Junctate is an integral sarco(endo)plasmic reticulum protein expressed in many tissues including heart and skeletal muscle. Because of its localization and biochemical characteristics, junctate is deemed to participate in the regulation of the intracellular Ca2+ concentration. However, its physiological function in muscle cells has not been investigated yet. In this study we examined the effects of junctate over-expression by generating a transgenic mouse model which over-expresses junctate in skeletal muscle. Our results demonstrate that junctate over-expression induced a significant increase in SR Ca2+ storage capacity which was paralleled by an increased 4-chloro-m-cresol and caffeine-induced Ca2+ release, whereas it did not affect SR Ca2+-dependent ATPase activity and SR Ca2+ loading rates. In addition, junctate over-expression did not affect the expression levels of SR Ca2+ binding proteins such as calsequestrin, calreticulin and sarcalumenin. These findings suggest that junctate over-expression is associated with an increase in the SR Ca2+ storage capacity and releasable Ca2+ content and support a physiological role for junctate in intracellular Ca2+ homeostasi