Imaging elementary events of calcium release in skeletal muscle cells

Science ◽  
1995 ◽  
Vol 269 (5231) ◽  
pp. 1723-1726 ◽  
Author(s):  
A Tsugorka ◽  
E Rios ◽  
L. Blatter
Keyword(s):  
Skeletal Muscle ◽  
Calcium Release ◽  
Muscle Cells ◽  
Skeletal Muscle Cells

NF-κB activation by depolarization of skeletal muscle cells depends on ryanodine and IP3 receptor-mediated calcium signals

2007 ◽  
Vol 292 (5) ◽  
pp. C1960-C1970 ◽  
Author(s):  
Juan Antonio Valdés ◽  
Jorge Hidalgo ◽  
José Luis Galaz ◽  
Natalia Puentes ◽  
Mónica Silva ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Calcium Release ◽  
Ryanodine Receptors ◽  
Field Potential ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Ip3 Receptor ◽  
Pharmacological Agents ◽  
Calcium Dependent ◽  
Element Binding Protein

Depolarization of skeletal muscle cells by either high external K+ or repetitive extracellular field potential pulses induces calcium release from internal stores. The two components of this release are mediated by either ryanodine receptors or inositol 1,4,5-trisphosphate (IP3) receptors and show differences in kinetics, amplitude, and subcellular localization. We have reported that the transcriptional regulators including ERKs, cAMP/Ca2+-response element binding protein, c- fos, c- jun, and egr-1 are activated by K+-induced depolarization and that their activation requires IP3-dependent calcium release. We presently describe the activation of the nuclear transcription factor NF-κB in response to depolarization by either high K+ (chronic) or electrical pulses (fluctuating). Calcium transients of relative short duration activate an NF-κB reporter gene to an intermediate level, whereas long-lasting calcium increases obtained by prolonged electrical stimulation protocols of various frequencies induce maximal activation of NF-κB. This activation is independent of extracellular calcium, whereas calcium release mediated by either ryanodine or IP3 receptors contribute in all conditions tested. NF-κB activation is mediated by IκBα degradation and p65 translocation to the nucleus. Partial blockade by N-acetyl-l-cysteine, a general antioxidant, suggests the participation of reactive oxygen species. Calcium-dependent signaling pathways such as those linked to calcineurin and PKC also contribute to NF-κB activation by depolarization, as assessed by blockade through pharmacological agents. These results suggest that NF-κB activation in skeletal muscle cells is linked to membrane depolarization and depends on the duration of elevated intracellular calcium. It can be regulated by sequential activation of calcium release mediated by the ryanodine and by IP3 receptors.

scholarly journals Identification of ER/SR resident proteins as biomarkers for ER/SR calcium depletion in skeletal muscle cells

2021 ◽  
Author(s):  
Lacey K. Greer ◽  
Katherine G. Meilleur ◽  
Brandon K. Harvey ◽  
Emily S. Wires
Keyword(s):  
Skeletal Muscle ◽  
Calcium Homeostasis ◽  
Plasma Levels ◽  
Calcium Release ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Calcium Handling ◽  
Calcium Depletion ◽  
Calcium Release Channel ◽  
Potential Biomarker

Aberrations to endoplasmic/sarcoplasmic reticulum (ER/SR) calcium concentration can result in the departure of endogenous proteins in a phenomenon termed exodosis. Redistribution of the ER/SR proteome can have deleterious effects to cell function and cell viability, often contributing to disease pathogenesis. Many proteins prone to exodosis reside in the ER/SR via an ER retention/retrieval sequence (ERS) and are involved in protein folding, protein modification, and protein trafficking. While the consequences of their extracellular presence have yet to be fully delineated, the proteins that have undergone exodosis may be useful for biomarker development. Skeletal muscle cells rely upon tightly coordinated ER/SR calcium release for muscle contractions, and perturbations to calcium homeostasis can result in myopathies. Ryanodine receptor type-1 (RYR1) is a calcium release channel located in the SR. Mutations to the RYR1 gene can compromise calcium homeostasis leading to a vast range of clinical phenotypes encompassing hypotonia, myalgia, respiratory insufficiency, ophthalmoplegia, fatigue and malignant hyperthermia (MH). There are currently no FDA approved treatments for RYR1-related myopathies (RYR1-RM). Here we examine the exodosis profile of skeletal muscle cells following ER/SR calcium depletion. Proteomic analysis identified 4,465 extracellular proteins following ER/SR calcium depletion with 1280 proteins significantly different than vehicle. A total of 54 ERS proteins were identified and 33 ERS proteins significantly increased following ER/SR calcium depletion. Specifically, ERS protein, mesencephalic astrocyte-derived neurotrophic factor (MANF), was elevated following calcium depletion, making it a potential biomarker candidate for human samples. Despite no significant elevation of MANF in plasma levels among healthy volunteers and RYR1-RM individuals, MANF plasma levels positively correlated with age in RYR1-RM individuals, presenting a potential biomarker of disease progression. Selenoprotein N (SEPN1) was also detected only in extracellular samples following ER/SR calcium depletion. This protein is integral to calcium handling and SEPN1 variants have a causal role in SEPN1-related myopathies (SEPN1-RM). Extracellular presence of ER/SR membrane proteins may provide new insight into proteomic alterations extending beyond ERS proteins. Pre-treatment of skeletal muscle cells with bromocriptine, an FDA approved drug recently found to have anti-exodosis effects, curbed exodosis of ER/SR resident proteins. Changes to the extracellular content caused by intracellular calcium dysregulation presents an opportunity for biomarker development and drug discovery.

scholarly journals Elementary calcium release events in the skeletal muscle cells of the honey bee Apis mellifera

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Claude Collet ◽  
Mercédès Charreton ◽  
Laszlo Szabo ◽  
Marianna Takacs ◽  
Laszlo Csernoch ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Honey Bee ◽  
Calcium Release ◽  
Ryanodine Receptors ◽  
Muscle Cells ◽  
Research Field ◽  
Confocal Imaging ◽  
Skeletal Muscle Cells ◽  
Muscle Fibres

AbstractCalcium sparks are involved in major physiological and pathological processes in vertebrate muscles but have never been characterized in invertebrates. Here, dynamic confocal imaging on intact skeletal muscle cells isolated enzymatically from the adult honey bee legs allowed the first spatio-temporal characterization of subcellular calcium release events (CREs) in an insect species. The frequency of CREs, measured in x–y time lapse series, was higher than frequencies usually described in vertebrates. Honey bee CREs had a larger spatial spread at half maximum than their vertebrate counterparts and a slightly ellipsoidal shape, two characteristics that may be related to ultrastructural features specific to invertebrate cells. In line-scan experiments, the histogram of CREs’ duration followed a bimodal distribution, supporting the existence of both sparks and embers. Unlike in vertebrates, embers and sparks had similar amplitudes, a difference that could be related to genomic differences and/or excitation–contraction coupling specificities in honey bee skeletal muscle fibres. The first characterization of CREs from an arthropod which shows strong genomic, ultrastructural and physiological differences with vertebrates may help in improving the research field of sparkology and more generally the knowledge in invertebrates cell Ca2+ homeostasis, eventually leading to a better understanding of their roles and regulations in muscles but also the myotoxicity of new insecticides targeting ryanodine receptors.

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