Toward the roles of store-operated Ca2+ entry in skeletal muscle

Launikonis, Bradley S.; Murphy, Robyn M.; Edwards, Joshua N.

doi:10.1007/s00424-010-0856-7

Cited by 63 publications

(93 citation statements)

References 63 publications

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“…An intriguing feature of SOCE in muscle is that it is orders of magnitude faster than in nonexcitable cells (Launikonis and Ríos 2007), commencing in some cases within milliseconds of Ca 2þ release from the SR . Several models have been proposed to explain how prelocalization of STIM1 and Orai1 at the triadic junction may confer these extraordinarily rapid activation kinetics (Dirksen 2009;Launikonis et al 2010).…”

Section: Skeletal Musclementioning

confidence: 99%

Store-Operated Calcium Channels: New Perspectives on Mechanism and Function

Lewis¹

2011

Cold Spring Harbor Perspectives in Biology

178

201

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Store-operated calcium channels (SOCs) are a nearly ubiquitous Ca 2þ entry pathway stimulated by numerous cell surface receptors via the reduction of Ca 2þ concentration in the ER. The discovery of STIM proteins as ER Ca 2þ sensors and Orai proteins as structural components of the Ca 2þ release-activated Ca 2þ (CRAC) channel, a prototypic SOC, opened the floodgates for exploring the molecular mechanism of this pathway and its functions. This review focuses on recent advances made possible by the use of STIM and Orai as molecular tools. I will describe our current understanding of the store-operated Ca 2þ entry mechanism and its emerging roles in physiology and disease, areas of uncertainty in which further progress is needed, and recent findings that are opening new directions for research in this rapidly growing field.

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Section: Skeletal Musclementioning

confidence: 99%

Store-Operated Calcium Channels: New Perspectives on Mechanism and Function

Lewis¹

2011

Cold Spring Harbor Perspectives in Biology

178

201

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“…This observation is even more pronounced in the case of triadin whose co-localization with JPH1 does not exceed 50%. [45,46], this may result in a greater propensity of these fibres to exhibit SOCE in such triads compared to fast-twitch fibres, unless they are closely associated with CSQ.…”

Section: A Schematic View Of Triad Organization In Extensor Digitorummentioning

confidence: 99%

Observation of the molecular organization of calcium release sites in fast- and slow-twitch skeletal muscle with nanoscale imaging

Jayasinghe

Munro

Baddeley

et al. 2014

J. R. Soc. Interface.

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Localization microscopy is a fairly recently introduced super-resolution fluorescence imaging modality capable of achieving nanometre-scale resolution. We have applied the dSTORM variation of this method to image intracellular molecular assemblies in skeletal muscle fibres which are large cells that critically rely on nanoscale signalling domains, the triads. Immunofluorescence staining in fixed adult rat skeletal muscle sections revealed clear differences between fast-and slow-twitch fibres in the molecular organization of ryanodine receptors (RyRs; the primary calcium release channels) within triads. With the improved resolution offered by dSTORM, abutting arrays of RyRs in transverse view of fast fibres were observed in contrast to the fragmented distribution on slow-twitch muscle that were approximately 1.8 times shorter and consisted of approximately 1.6 times fewer receptors. To the best of our knowledge, for the first time, we have quantified the nanometre-scale spatial association between triadic proteins using multi-colour super-resolution, an analysis difficult to conduct with electron microscopy. Our findings confirm that junctophilin-1 (JPH1), which tethers the sarcoplasmic reticulum ((SR) intracellular calcium store) to the tubular (t-) system at triads, was present throughout the RyR array, whereas JPH2 was contained within much smaller nanodomains. Similar imaging of the primary SR calcium buffer, calsequestrin (CSQ), detected less overlap of the triad with CSQ in slow-twitch muscle supporting greater spatial heterogeneity in the luminal Ca 2þ buffering when compared with fast twitch muscle. Taken together, these nanoscale differences can explain the fundamentally different physiologies of fast-and slow-twitch muscle.

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“…Subsequent [Ca 2ϩ ] c decrease brings about skeletal muscle relaxation via multiple mechanisms: Ca 2ϩ reuptake and storage in the SR by Ca 2ϩ ATPase (SERCA) and calsequestrin (CASQ), respectively; Ca 2ϩ binding by cytoplasmic proteins, such as parvalbumin; and, locally, Ca 2ϩ uptake by mitochondria (18,46). Recently, a mechanism involved in Ca 2ϩ store refilling (store-operated calcium entry) has been described not only in nonexcitable cells but also in skeletal muscle (22) where it might play a role in specific conditions entailing prolonged stimulations and, thus, leading to Ca 2ϩ store depletion (23).…”

mentioning

confidence: 98%

Calsequestrin (CASQ1) rescues function and structure of calcium release units in skeletal muscles of CASQ1-null mice

Tomasi

Canato

Paolini

et al. 2012

American Journal of Physiology-Cell Physiology

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Amplitude of Ca(2+) transients, ultrastructure of Ca(2+) release units, and molecular composition of sarcoplasmic reticulum (SR) are altered in fast-twitch skeletal muscles of calsequestrin-1 (CASQ1)-null mice. To determine whether such changes are directly caused by CASQ1 ablation or are instead the result of adaptive mechanisms, here we assessed ability of CASQ1 in rescuing the null phenotype. In vivo reintroduction of CASQ1 was carried out by cDNA electro transfer in flexor digitorum brevis muscle of the mouse. Exogenous CASQ1 was found to be correctly targeted to the junctional SR (jSR), as judged by immunofluorescence and confocal microscopy; terminal cisternae (TC) lumen was filled with electron dense material and its width was significantly increased, as judged by electron microscopy; peak amplitude of Ca(2+) transients was significantly increased compared with null muscle fibers transfected only with green fluorescent protein (control); and finally, transfected fibers were able to sustain cytosolic Ca(2+) concentration during prolonged tetanic stimulation. Only the expression of TC proteins, such as calsequestrin 2, sarcalumenin, and triadin, was not rescued as judged by Western blot. Thus our results support the view that CASQ1 plays a key role in both Ca(2+) homeostasis and TC structure.

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Toward the roles of store-operated Ca2+ entry in skeletal muscle

Cited by 63 publications

References 63 publications

Store-Operated Calcium Channels: New Perspectives on Mechanism and Function

Store-Operated Calcium Channels: New Perspectives on Mechanism and Function

Observation of the molecular organization of calcium release sites in fast- and slow-twitch skeletal muscle with nanoscale imaging

Calsequestrin (CASQ1) rescues function and structure of calcium release units in skeletal muscles of CASQ1-null mice

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