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Pearce L, Meizoso-Huesca A, Seng C, Lamboley CR, Singh DP, Launikonis BS. Ryanodine receptor activity and store-operated Ca 2+ entry: Critical regulators of Ca 2+ content and function in skeletal muscle. J Physiol 2023; 601:4183-4202. [PMID: 35218018 DOI: 10.1113/jp279512] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/28/2022] [Indexed: 11/08/2022] Open
Abstract
Store-operated Ca2+ entry (SOCE) is critical to cell function. In skeletal muscle, SOCE has evolved alongside excitation-contraction coupling (EC coupling); as a result, it displays unique properties compared to SOCE in other cells. The plasma membrane of skeletal muscle is mostly internalized as the tubular system, with the tubules meeting the sarcoplasmic reticulum (SR) terminal cisternae, forming junctions where the proteins that regulate EC coupling and SOCE are positioned. In this review, we describe the properties and roles of SOCE based on direct measurements of Ca2+ influx during SR Ca2+ release and leak. SOCE is activated immediately and locally as the [Ca2+ ] of the junctional SR terminal cisternae ([Ca2+ ]jSR ) depletes. [Ca2+ ]jSR changes rapidly and steeply with increasing activity of the SR ryanodine receptor isoform 1 (RyR1). The high fidelity of [Ca2+ ]jSR with RyR1 activity probably depends on the SR Ca2+ -buffer calsequestrin that is located immediately behind RyR1 inside the SR. This arrangement provides in-phase activation and deactivation of SOCE with a large dynamic range, allowing precise grading of SOCE flux. The in-phase activation of SOCE as the SR partially depletes traps Ca2+ in the cytoplasm, preventing net Ca2+ loss. Mild presentation of RyR1 leak can occur under physiological conditions, providing fibre Ca2+ redistribution without changing fibre Ca2+ content. This condition preserves normal contractile function at the same time as increasing basal metabolic rate. However, higher RyR1 leak drives excess cytoplasmic and mitochondrial Ca2+ load, setting a deleterious intracellular environment that compromises the function of the skeletal muscle.
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Affiliation(s)
- Luke Pearce
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Aldo Meizoso-Huesca
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Crystal Seng
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Cedric R Lamboley
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Daniel P Singh
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Bradley S Launikonis
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
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Bolaños P, Calderón JC. Excitation-contraction coupling in mammalian skeletal muscle: Blending old and last-decade research. Front Physiol 2022; 13:989796. [PMID: 36117698 PMCID: PMC9478590 DOI: 10.3389/fphys.2022.989796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
The excitation–contraction coupling (ECC) in skeletal muscle refers to the Ca2+-mediated link between the membrane excitation and the mechanical contraction. The initiation and propagation of an action potential through the membranous system of the sarcolemma and the tubular network lead to the activation of the Ca2+-release units (CRU): tightly coupled dihydropyridine and ryanodine (RyR) receptors. The RyR gating allows a rapid, massive, and highly regulated release of Ca2+ from the sarcoplasmic reticulum (SR). The release from triadic places generates a sarcomeric gradient of Ca2+ concentrations ([Ca2+]) depending on the distance of a subcellular region from the CRU. Upon release, the diffusing Ca2+ has multiple fates: binds to troponin C thus activating the contractile machinery, binds to classical sarcoplasmic Ca2+ buffers such as parvalbumin, adenosine triphosphate and, experimentally, fluorescent dyes, enters the mitochondria and the SR, or is recycled through the Na+/Ca2+ exchanger and store-operated Ca2+ entry (SOCE) mechanisms. To commemorate the 7th decade after being coined, we comprehensively and critically reviewed “old”, historical landmarks and well-established concepts, and blended them with recent advances to have a complete, quantitative-focused landscape of the ECC. We discuss the: 1) elucidation of the CRU structures at near-atomic resolution and its implications for functional coupling; 2) reliable quantification of peak sarcoplasmic [Ca2+] using fast, low affinity Ca2+ dyes and the relative contributions of the Ca2+-binding mechanisms to the whole concert of Ca2+ fluxes inside the fibre; 3) articulation of this novel quantitative information with the unveiled structural details of the molecular machinery involved in mitochondrial Ca2+ handing to understand how and how much Ca2+ enters the mitochondria; 4) presence of the SOCE machinery and its different modes of activation, which awaits understanding of its magnitude and relevance in situ; 5) pharmacology of the ECC, and 6) emerging topics such as the use and potential applications of super-resolution and induced pluripotent stem cells (iPSC) in ECC. Blending the old with the new works better!
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Affiliation(s)
- Pura Bolaños
- Laboratory of Cellular Physiology, Centre of Biophysics and Biochemistry, Venezuelan Institute for Scientific Research (IVIC), Caracas, Venezuela
| | - Juan C. Calderón
- Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellín, Colombia
- *Correspondence: Juan C. Calderón,
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Lilliu E, Koenig S, Koenig X, Frieden M. Store-Operated Calcium Entry in Skeletal Muscle: What Makes It Different? Cells 2021; 10:cells10092356. [PMID: 34572005 PMCID: PMC8468011 DOI: 10.3390/cells10092356] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/03/2021] [Accepted: 09/04/2021] [Indexed: 01/26/2023] Open
Abstract
Current knowledge on store-operated Ca2+ entry (SOCE) regarding its localization, kinetics, and regulation is mostly derived from studies performed in non-excitable cells. After a long time of relative disinterest in skeletal muscle SOCE, this mechanism is now recognized as an essential contributor to muscle physiology, as highlighted by the muscle pathologies that are associated with mutations in the SOCE molecules STIM1 and Orai1. This review mainly focuses on the peculiar aspects of skeletal muscle SOCE that differentiate it from its counterpart found in non-excitable cells. This includes questions about SOCE localization and the movement of respective proteins in the highly organized skeletal muscle fibers, as well as the diversity of expressed STIM isoforms and their differential expression between muscle fiber types. The emerging evidence of a phasic SOCE, which is activated during EC coupling, and its physiological implication is described as well. The specific issues related to the use of SOCE modulators in skeletal muscles are discussed. This review highlights the complexity of SOCE activation and its regulation in skeletal muscle, with an emphasis on the most recent findings and the aim to reach a current picture of this mesmerizing phenomenon.
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Affiliation(s)
- Elena Lilliu
- Center for Physiology and Pharmacology, Department of Neurophysiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria;
| | - Stéphane Koenig
- Department of Cell Physiology and Metabolism, University of Geneva, 1201 Geneva, Switzerland;
| | - Xaver Koenig
- Center for Physiology and Pharmacology, Department of Neurophysiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria;
- Correspondence: (X.K.); (M.F.)
| | - Maud Frieden
- Department of Cell Physiology and Metabolism, University of Geneva, 1201 Geneva, Switzerland;
- Correspondence: (X.K.); (M.F.)
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Meizoso-Huesca A, Launikonis BS. The Orai1 inhibitor BTP2 has multiple effects on Ca2+ handling in skeletal muscle. J Gen Physiol 2020; 153:211591. [PMID: 33316029 PMCID: PMC7735889 DOI: 10.1085/jgp.202012747] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 10/21/2020] [Accepted: 11/17/2020] [Indexed: 12/15/2022] Open
Abstract
BTP2 is an inhibitor of the Ca2+ channel Orai1, which mediates store-operated Ca2+ entry (SOCE). Despite having been extensively used in skeletal muscle, the effects of this inhibitor on Ca2+ handling in muscle cells have not been described. To address this question, we used intra- and extracellular application of BTP2 in mechanically skinned fibers and developed a localized modulator application approach, which provided in-preparation reference and test fiber sections to enhance detection of the effect of Ca2+ handling modulators. In addition to blocking Orai1-dependent SOCE, we found a BTP2-dependent inhibition of resting extracellular Ca2+ flux. Increasing concentrations of BTP2 caused a shift from inducing accumulation of Ca2+ in the t-system due to Orai1 blocking to reducing the resting [Ca2+] in the sealed t-system. This effect was not observed in the absence of functional ryanodine receptors (RYRs), suggesting that higher concentrations of BTP2 impair RYR function. Additionally, we found that BTP2 impaired action potential–induced Ca2+ release from the sarcoplasmic reticulum during repetitive stimulation without compromising the fiber Ca2+ content. BTP2 was found to have an effect on RYR-mediated Ca2+ release, suggesting that RYR is the point of BTP2-induced inhibition during cycles of EC coupling. The effects of BTP2 on the RYR Ca2+ leak and release were abolished by pre-exposure to saponin, indicating that the effects of BTP2 on the RYR are not direct and require a functional t-system. Our results demonstrate the presence of a SOCE channels–mediated basal Ca2+ influx in healthy muscle fibers and indicate that BTP2 has multiple effects on Ca2+ handling, including indirect effects on the activity of the RYR.
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Affiliation(s)
- Aldo Meizoso-Huesca
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Bradley S Launikonis
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
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Hsu SS, Liang WZ. Ca 2+ signaling as a mechanism of haloperidol-induced cytotoxicity in human astrocytes and assessing the protective role of a Ca 2+ chelator. Naunyn Schmiedebergs Arch Pharmacol 2020; 393:2117-2127. [PMID: 32594194 DOI: 10.1007/s00210-020-01929-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/18/2020] [Indexed: 11/28/2022]
Abstract
Haloperidol, a typical antipsychotic medication, has been shown to possess various biological effects in different brain models. However, the impact of haloperidol on Ca2+ signaling in astrocytes is elusive. This study explored the effect of haloperidol on cytosolic free Ca2+ levels ([Ca2+]i) and viability, and established these two connections in Gibco® Human Astrocytes (GHAs) and DI TNC1 rat astrocytes. Haloperidol (5-20 μM) caused [Ca2+]i rises in a concentration-dependent manner in GHAs but not in DI TNC1 cells. Furthermore, removal of extracellular Ca2+ reduced haloperidol's effect by approximately 30% in GHAs. Haloperidol (20-40 μM) evoked concentration-dependent cytotoxicity in GHAs and DI TNC1 cells. However, chelating cytosolic Ca2+ with the Ca2+ chelator BAPTA/AM significantly reversed haloperidol's cytotoxicity only in GHAs. In GHAs, haloperidol-induced Ca2+ entry was inhibited by store-operated Ca2+ modulators (2-APB and SKF96365) and the protein kinase C (PKC) inhibitor GF109203X. This Ca2+ entry induced by haloperidol was confirmed by Mn2+ entry-induced quench of fura-2 fluorescence. In Ca2+-free medium, treatment with the endoplasmic reticulum Ca2+ pump inhibitor 2,5-di-tert-butylhydroquinone (BHQ) abolished haloperidol-induced [Ca2+]i rises. Conversely, treatment with haloperidol inhibited 45% of BHQ-evoked [Ca2+]i rises. Moreover, haloperidol-induced Ca2+ release from the endoplasmic reticulum was abolished by inhibition of phospholipase C (PLC) by U73122. Together, in GHAs but not in DI TNC1 cells, haloperidol caused Ca2+-associated cell death, induced Ca2+ entry via PKC-sensitive store-operated Ca2+ channels, and evoked PLC-dependent Ca2+ release from the endoplasmic reticulum. The protective effect of Ca2+ chelating on haloperidol-induced cytotoxicity in human astrocytes was also demonstrated.
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Affiliation(s)
- Shu-Shong Hsu
- Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, 81362, Taiwan.,Department of Surgery, National Defense Medical Center, Taipei, 11490, Taiwan.,College of Health and Nursing, Meiho University, Pingtung, 91202, Taiwan
| | - Wei-Zhe Liang
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, 81362, Taiwan. .,Department of Pharmacy and Master Program, College of Pharmacy and Health Care, Tajen University, Pingtung County, 90741, Taiwan.
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Cheng H, Curtis AE, Fellingham C, Hancox JC. Multiple ion channel block by the cation channel inhibitor SKF-96365 in myocytes from the rabbit atrioventricular node. Physiol Rep 2016; 4:4/11/e12819. [PMID: 27288059 PMCID: PMC4908495 DOI: 10.14814/phy2.12819] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 05/12/2016] [Indexed: 12/31/2022] Open
Abstract
The atrioventricular node (AVN) of the cardiac conduction system coordinates atrial-ventricular excitation and can act as a subsidiary pacemaker. Recent evidence suggests that an inward background sodium current, IB,Na, carried by nonselective cation channels (NSCCs), contributes to AVN cell pacemaking. The study of the physiological contribution of IB,Na has been hampered, however, by a lack of selective pharmacological antagonists. This study investigated effects of the NSCC inhibitor SKF-96365 on spontaneous activity, IB,Na, and other ionic currents in AVN cells isolated from the rabbit. Whole-cell patch-clamp recordings of action potentials (APs) and ionic currents were made at 35-37°C. A concentration of 10 μmol/L SKF-96365 slowed spontaneous action potential rate by 13.9 ± 5.3% (n = 8) and slope of the diastolic depolarization from 158.1 ± 30.5 to 86.8 ± 30.5 mV sec(-1) (P < 0.01; n = 8). Action potential upstroke velocity and maximum diastolic potential were also reduced. Under IB,Na-selective conditions, 10 μmol/L SKF-96365 inhibited IB,Na at -50 mV by 36.1 ± 6.8% (n = 8); however, effects on additional channel currents were also observed. Thus, the peak l-type calcium current (ICa,L) at +10 mV was inhibited by 38.6 ± 8.1% (n = 8), while the rapid delayed rectifier current, IKr, tails at -40 mV following depolarization to +20 mV were inhibited by 55.6 ± 4.6% (n = 8). The hyperpolarization-activated current, If, was unaffected by SKF-96365. Collectively, these results indicate that SKF-96365 exerts a moderate inhibitory effect on IB,Na and slows AVN cell pacemaking. However, additional effects of the compound on ICa,L and IKr confound the use of SKF-96365 to dissect out selectively the physiological role of IB,Na in the AVN.
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Affiliation(s)
- Hongwei Cheng
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology and Neuroscience University of Bristol, Bristol, UK
| | - Alexander E Curtis
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology and Neuroscience University of Bristol, Bristol, UK
| | - Claire Fellingham
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology and Neuroscience University of Bristol, Bristol, UK
| | - Jules C Hancox
- Cardiovascular Research Laboratories, School of Physiology, Pharmacology and Neuroscience University of Bristol, Bristol, UK
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Fransen P, Van Hove CE, Leloup AJA, Martinet W, De Meyer GRY, Lemmens K, Bult H, Schrijvers DM. Dissecting out the complex Ca2+-mediated phenylephrine-induced contractions of mouse aortic segments. PLoS One 2015; 10:e0121634. [PMID: 25803863 PMCID: PMC4372603 DOI: 10.1371/journal.pone.0121634] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 02/12/2015] [Indexed: 01/04/2023] Open
Abstract
L-type Ca2+ channel (VGCC) mediated Ca2+ influx in vascular smooth muscle cells (VSMC) contributes to the functional properties of large arteries in arterial stiffening and central blood pressure regulation. How this influx relates to steady-state contractions elicited by α1-adrenoreceptor stimulation and how it is modulated by small variations in resting membrane potential (Vm) of VSMC is not clear yet. Here, we show that α1-adrenoreceptor stimulation of aortic segments of C57Bl6 mice with phenylephrine (PE) causes phasic and tonic contractions. By studying the relationship between Ca2+ mobilisation and isometric tension, it was found that the phasic contraction was due to intracellular Ca2+ release and the tonic contraction determined by Ca2+ influx. The latter component involves both Ca2+ influx via VGCC and via non-selective cation channels (NSCC). Influx via VGCC occurs only within the window voltage range of the channel. Modulation of this window Ca2+ influx by small variations of the VSMC Vm causes substantial effects on the contractile performance of aortic segments. The relative contribution of VGCC and NSCC to the contraction by α1-adrenoceptor stimulation could be manipulated by increasing intracellular Ca2+ release from non-contractile sarcoplasmic reticulum Ca2+ stores. Results of this study point to a complex interactions between α1-adrenoceptor-mediated VSMC contractile performance and Ca2+ release form contractile or non-contractile Ca2+ stores with concomitant Ca2+ influx. Given the importance of VGCC and their blockers in arterial stiffening and hypertension, they further point toward an additional role of NSCC (and NSCC blockers) herein.
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Affiliation(s)
- Paul Fransen
- Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
- * E-mail:
| | - Cor E. Van Hove
- Department of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Arthur J. A. Leloup
- Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | - Wim Martinet
- Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | | | - Katrien Lemmens
- Department of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Hidde Bult
- Department of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
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Sabourin J, Robin E, Raddatz E. A key role of TRPC channels in the regulation of electromechanical activity of the developing heart. Cardiovasc Res 2011; 92:226-36. [PMID: 21672930 DOI: 10.1093/cvr/cvr167] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
AIMS It is well established that dysfunction of voltage-dependent ion channels results in arrhythmias and conduction disturbances in the foetal and adult heart. However, the involvement of voltage-insensitive cationic TRPC (transient receptor potential canonical) channels remains unclear. We assessed the hypothesis that TRPC channels play a crucial role in the spontaneous activity of the developing heart. METHODS AND RESULTS TRPC isoforms were investigated in isolated hearts obtained from 4-day-old chick embryos. Using RT-PCR, western blotting and co-immunoprecipitation, we report for the first time that TRPC1, 3, 4, 5, 6, and 7 isoforms are expressed at the mRNA and protein levels and that they can form a macromolecular complex with the α1C subunit of the L-type voltage-gated calcium channel (Cav1.2) in atria and ventricle. Using ex vivo electrocardiograms, electrograms of isolated atria and ventricle and ventricular mechanograms, we found that inhibition of TRPC channels by SKF-96365 leads to negative chrono-, dromo-, and inotropic effects, prolongs the QT interval, and provokes first- and second-degree atrioventricular blocks. Pyr3, a specific antagonist of TRPC3, affected essentially atrioventricular conduction. On the other hand, specific blockade of the L-type calcium channel with nifedipine rapidly stopped ventricular contractile activity without affecting rhythmic electrical activity. CONCLUSIONS These results give new insights into the key role that TRPC channels, via interaction with the Cav1.2 channel, play in regulation of cardiac pacemaking, conduction, ventricular activity, and contractility during cardiogenesis.
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Affiliation(s)
- Jessica Sabourin
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, 7 rue du Bugnon, CH-1005 Lausanne, Switzerland.
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