New aspects of calcium signaling in skeletal muscle cells: implications in Duchenne muscular dystrophy.

(2002) Biochimica et Biophysica Acta : international journal of biochemistry and biophysics — Vol. 1600, n° 1-2, p. 38-44 (2002)

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Abstract
Calcium is the most ubiquitous second messenger. Its concentration inside the cell is tightly regulated by a series of mechanisms, among which some have been extensively studied in nonmuscle cells. This is the case of the "store-operated entry of Ca(2+)", the uptake of Ca(2+) by mitochondria and the inositol 1,4,5-trisphosphate (IP(3)) cascade. These processes were recently found to be also present in skeletal muscle and are reviewed here. The "store-operated entry of Ca(2+)" allows the refilling of the stores after muscle fiber depolarization and is activated even after a partial depletion of the sarcoplasmic reticulum (SR). The uptake of Ca(2+) by mitochondria accelerates muscle relaxation and allows the adaptation of ATP supply to the increased energy demand. IP(3) receptors are found in the nuclear envelope and are involved in Ca(2+) waves propagating from one nucleus to another. This pathway is possibly involved in gene expression regulation. Finally, cytosolic Ca(2+) buffers like parvalbumins modify [Ca(2+)](i) transients and, therefore, muscle mechanics.The importance of these regulation mechanisms is also evaluated in Duchenne muscular dystrophy (DMD), a disease in which impairment of [Ca(2+)](i) homeostasis has been postulated but remains, however, controversial. This genetic disease is indeed characterized by the absence of a cytoskeletal protein called dystrophin, a situation leading to a disorganization of the cytoskeleton and to an abnormal influx of Ca(2+). How this increased entry of Ca(2+) affects the local concentration of Ca(2+) in subcellular compartments and whether this process is involved in the development of the disease are still unclear.
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Gailly, P. (2002). New aspects of calcium signaling in skeletal muscle cells: implications in Duchenne muscular dystrophy. Biochimica et Biophysica Acta : international journal of biochemistry and biophysics, 1600(1-2), 38-44. https://hdl.handle.net/2078.5/35584 (Original work published 2002)