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Del Olmo M, Legewie S, Brunner M, Höfer T, Kramer A, Blüthgen N, Herzel H. Network switches and their role in circadian clocks. J Biol Chem 2024; 300:107220. [PMID: 38522517 PMCID: PMC11044057 DOI: 10.1016/j.jbc.2024.107220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 03/07/2024] [Accepted: 03/18/2024] [Indexed: 03/26/2024] Open
Abstract
Circadian rhythms are generated by complex interactions among genes and proteins. Self-sustained ∼24 h oscillations require negative feedback loops and sufficiently strong nonlinearities that are the product of molecular and network switches. Here, we review common mechanisms to obtain switch-like behavior, including cooperativity, antagonistic enzymes, multisite phosphorylation, positive feedback, and sequestration. We discuss how network switches play a crucial role as essential components in cellular circadian clocks, serving as integral parts of transcription-translation feedback loops that form the basis of circadian rhythm generation. The design principles of network switches and circadian clocks are illustrated by representative mathematical models that include bistable systems and negative feedback loops combined with Hill functions. This work underscores the importance of negative feedback loops and network switches as essential design principles for biological oscillations, emphasizing how an understanding of theoretical concepts can provide insights into the mechanisms generating biological rhythms.
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Affiliation(s)
- Marta Del Olmo
- Institute for Theoretical Biology, Humboldt Universität zu Berlin and Charité Universitätsmedizin Berlin, Berlin, Germany.
| | - Stefan Legewie
- Department of Systems Biology, Institute for Biomedical Genetics (IBMG), University of Stuttgart, Stuttgart, Germany; Stuttgart Research Center for Systems Biology (SRCSB), University of Stuttgart, Stuttgart, Germany
| | - Michael Brunner
- Biochemistry Center, Universität Heidelberg, Heidelberg, Germany
| | - Thomas Höfer
- Division of Theoretical Systems Biology, German Cancer Research Center (DKFZ), Universität Heidelberg, Heidelberg, Germany
| | - Achim Kramer
- Laboratory of Chronobiology, Institute for Medical Immunology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Nils Blüthgen
- Institute for Theoretical Biology, Humboldt Universität zu Berlin and Charité Universitätsmedizin Berlin, Berlin, Germany; Institute of Pathology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Hanspeter Herzel
- Institute for Theoretical Biology, Humboldt Universität zu Berlin and Charité Universitätsmedizin Berlin, Berlin, Germany.
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Magyar ZÉ, Bauer J, Bauerová-Hlinková V, Jóna I, Gaburjakova J, Gaburjakova M, Almássy J. Eu 3+ detects two functionally distinct luminal Ca 2+ binding sites in ryanodine receptors. Biophys J 2023; 122:3516-3531. [PMID: 37533257 PMCID: PMC10502479 DOI: 10.1016/j.bpj.2023.07.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 06/26/2023] [Accepted: 07/31/2023] [Indexed: 08/04/2023] Open
Abstract
Ryanodine receptors (RyRs) are Ca2+ release channels, gated by Ca2+ in the cytosol and the sarcoplasmic reticulum lumen. Their regulation is impaired in certain cardiac and muscle diseases. Although a lot of data is available on the luminal Ca2+ regulation of RyR, its interpretation is complicated by the possibility that the divalent ions used to probe the luminal binding sites may contaminate the cytoplasmic sites by crossing the channel pore. In this study, we used Eu3+, an impermeable agonist of Ca2+ binding sites, as a probe to avoid this complication and to gain more specific information about the function of the luminal Ca2+ sensor. Single-channel currents were measured from skeletal muscle and cardiac RyRs (RyR1 and RyR2) using the lipid bilayer technique. We show that RyR2 is activated by the luminal addition of Ca2+, whereas RyR1 is inhibited. These results were qualitatively reproducible using Eu3+. The luminal regulation of RyR1 carrying a mutation associated with malignant hyperthermia was not different from that of the wild-type. RyR1 inhibition by Eu3+ was extremely voltage dependent, whereas RyR2 activation did not depend on the membrane potential. These results suggest that the RyR1 inhibition site is in the membrane's electric field (channel pore), whereas the RyR2 activation site is outside. Using in silico analysis and previous results, we predicted putative Ca2+ binding site sequences. We propose that RyR2 bears an activation site, which is missing in RyR1, but both isoforms share the same inhibitory Ca2+ binding site near the channel gate.
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Affiliation(s)
- Zsuzsanna É Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Jacob Bauer
- Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | | | - István Jóna
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Jana Gaburjakova
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Marta Gaburjakova
- Institute of Molecular Physiology and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia
| | - János Almássy
- Department of Physiology, Semmelweis University, Budapest, Hungary.
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3
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Kong CHT, Cannell MB. Ca 2+ spark latency and control of intrinsic Ca 2+ release dyssynchrony in rat cardiac ventricular muscle cells. J Mol Cell Cardiol 2023; 182:44-53. [PMID: 37433391 PMCID: PMC7616665 DOI: 10.1016/j.yjmcc.2023.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/12/2023] [Accepted: 07/06/2023] [Indexed: 07/13/2023]
Abstract
Cardiac excitation-contraction coupling (ECC) depends on Ca2+ release from intracellular stores via ryanodine receptors (RyRs) triggered by L-type Ca2+ channels (LCCs). Uncertain numbers of RyRs and LCCs form 'couplons' whose activation produces Ca2+ sparks, which summate to form a cell-wide Ca2+ transient that switches on contraction. Voltage (Vm) changes during the action potential (AP) and stochasticity in channel gating should create variability in Ca2+ spark timing, but Ca2+ transient wavefronts have remarkable uniformity. To examine how this is achieved, we measured the Vm-dependence of evoked Ca2+ spark probability (Pspark) and latency over a wide voltage range in rat ventricular cells. With depolarising steps, Ca2+ spark latency showed a U-shaped Vm-dependence, while repolarising steps from 50 mV produced Ca2+ spark latencies that increased monotonically with Vm. A computer model based on reported channel gating and geometry reproduced our experimental data and revealed a likely RyR:LCC stoichiometry of ∼ 5:1 for the Ca2+ spark initiating complex (IC). Using the experimental AP waveform, the model revealed a high coupling fidelity (Pcpl ∼ 0.5) between each LCC opening and IC activation. The presence of ∼ 4 ICs per couplon reduced Ca2+ spark latency and increased Pspark to match experimental data. Variability in AP release timing is less than that seen with voltage steps because the AP overshoot and later repolarization decrease Pspark due to effects on LCC flux and LCC deactivation respectively. This work provides a framework for explaining the Vm- and time-dependence of Pspark, and indicates how ion channel dispersion in disease can contribute to dyssynchrony in Ca2+ release.
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Affiliation(s)
- Cherrie H T Kong
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.
| | - Mark B Cannell
- School of Physiology, Pharmacology and Neuroscience, Faculty of Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.
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Paudel R, Jafri MS, Ullah A. The Role of Ca 2+ Sparks in Force Frequency Relationships in Guinea Pig Ventricular Myocytes. Biomolecules 2022; 12:1577. [PMID: 36358926 PMCID: PMC9687237 DOI: 10.3390/biom12111577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 10/19/2022] [Accepted: 10/21/2022] [Indexed: 10/13/2023] Open
Abstract
Calcium sparks are the elementary Ca2+ release events in excitation-contraction coupling that underlie the Ca2+ transient. The frequency-dependent contractile force generated by cardiac myocytes depends upon the characteristics of the Ca2+ transients. A stochastic computational local control model of a guinea pig ventricular cardiomyocyte was developed, to gain insight into mechanisms of force-frequency relationship (FFR). This required the creation of a new three-state RyR2 model that reproduced the adaptive behavior of RyR2, in which the RyR2 channels transition into a different state when exposed to prolonged elevated subspace [Ca2+]. The model simulations agree with previous experimental and modeling studies on interval-force relations. Unlike previous common pool models, this local control model displayed stable action potential trains at 7 Hz. The duration and the amplitude of the [Ca2+]myo transients increase in pacing rates consistent with the experiments. The [Ca2+]myo transient reaches its peak value at 4 Hz and decreases afterward, consistent with experimental force-frequency curves. The model predicts, in agreement with previous modeling studies of Jafri and co-workers, diastolic sarcoplasmic reticulum, [Ca2+]sr, and RyR2 adaptation increase with the increased stimulation frequency, producing rising, rather than falling, amplitude of the myoplasmic [Ca2+] transients. However, the local control model also suggests that the reduction of the L-type Ca2+ current, with an increase in pacing frequency due to Ca2+-dependent inactivation, also plays a role in the negative slope of the FFR. In the simulations, the peak Ca2+ transient in the FFR correlated with the highest numbers of SR Ca2+ sparks: the larger average amplitudes of those sparks, and the longer duration of the Ca2+ sparks.
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Affiliation(s)
- Roshan Paudel
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA
- School of Computer, Mathematical, and Natural Sciences, Morgan State University, Baltimore, MD 21251, USA
| | - Mohsin Saleet Jafri
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 20201, USA
| | - Aman Ullah
- School of Systems Biology, George Mason University, Fairfax, VA 22030, USA
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Folkerts EJ, Snihur KN, Zhang Y, Martin JW, Alessi DS, Goss GG. Embryonic cardio-respiratory impairments in rainbow trout (Oncorhynchus mykiss) following exposure to hydraulic fracturing flowback and produced water. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 310:119886. [PMID: 35934150 DOI: 10.1016/j.envpol.2022.119886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 07/29/2022] [Accepted: 07/31/2022] [Indexed: 06/15/2023]
Abstract
During hydraulic fracturing, wastewaters - termed flowback and produced water (FPW) - are created as a by-product during hydrocarbon extraction. Given the large volumes of FPW that a single well can produce, and the history of FPW release to surface water bodies, it is imperative to understand the hazards that hydraulic fracturing and FPW pose to aquatic biota. Using rainbow trout embryos as model organisms, we investigated impacts to cardio-respiratory system development and function following acute (48 h) and sub-chronic (28-day) FPW exposure by examining occurrences of developmental deformities, rates of embryonic respiration (MO2), and changes in expression of critical cardiac-specific genes. FPW-exposed embryos had significantly increased rates of pericardial edema, yolk-sac edema, and tail/trunk curvatures at hatch. Furthermore, when exposed at three days post-fertilization (dpf), acute 5% FPW exposures significantly increased embryonic MO2 through development until 15 dpf, where a switch to significantly reduced MO2 rates was subsequently recorded. A similar trend was observed during sub-chronic 1% FPW exposures. Interestingly, at certain specific developmental timepoints, previous salinity exposure seemed to affect embryonic MO2; a result not previously observed. Following acute FPW exposures, embryonic genes for cardiac development and function were significantly altered, although at termination of sub-chronic exposures, significant changes to these same genes were not found. Together, our evidence of induced developmental deformities, modified embryonic MO2, and altered cardiac transcript expression suggest that cardio-respiratory tissues are toxicologically targeted following FPW exposure in developing rainbow trout. These results may be helpful to regulatory bodies when developing hazard identification and risk management protocols concerning hydraulic fracturing activities.
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Affiliation(s)
- Erik J Folkerts
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada.
| | - Katherine N Snihur
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, T6G 2E3, Canada
| | - Yifeng Zhang
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, T6G 2G3, Alberta, Canada
| | - Jonathan W Martin
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, T6G 2G3, Alberta, Canada; Department of Environmental Science, Stockholm University, Stockholm, Sweden
| | - Daniel S Alessi
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, T6G 2E3, Canada
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada; NRC- University of Alberta Nanotechnology Initiative, Edmonton, AB, T6G 2M9, Canada
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6
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Alharbi KS, Singh Y, Afzal O, Alfawaz Altamimi AS, Kazmi I, Al-Abbasi FA, Alzarea SI, Chellappan DK, Singh SK, Dua K, Gupta G. Molecular explanation of Wnt/βcatenin antagonist pyrvinium mediated calcium equilibrium changes in aging cardiovascular disorders. Mol Biol Rep 2022; 49:11101-11111. [DOI: 10.1007/s11033-022-07863-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/10/2022] [Accepted: 08/11/2022] [Indexed: 10/14/2022]
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7
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Chen J, Liu Z, Deng F, Liang J, Fan B, Zhen X, Tao R, Sun L, Zhang S, Cong Z, Li X, Du W. Mechanisms of Lian-Gui-Ning-Xin-Tang in the treatment of arrhythmia: Integrated pharmacology and in vivo pharmacological assessment. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2022; 99:153989. [PMID: 35272242 DOI: 10.1016/j.phymed.2022.153989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 01/27/2022] [Accepted: 02/10/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND Lian-Gui-Ning-Xin-Tang (LGNXT), a classical traditional Chinese medicine (TCM) formula, has been widely used in clinical practice and has shown satisfactory efficacy in the treatment of arrhythmias. However, its mechanism of action in the treatment of arrhythmias is still unknown. Moreover, the complex chemical composition and therapeutic targets of LGNXT pose a challenge in pharmacological research. PURPOSE To analyze the active compounds and action mechanisms of LGNXT for the treatment of arrhythmias. METHODS Here, we used an integrated pharmacology approach to identify the potential active compounds and mechanisms of action of LGNXT in treating arrhythmias. Potential active compounds in LGNXT were identified using ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS) and the potential related targets of these compounds were predicted using an integrated in silico approach. The obtained targets were mapped onto relevant databases to identify their corresponding pathways, following the experiments that were conducted to confirm whether the presumptive results of systemic pharmacology were correct. RESULTS Eighty-three components were identified in herbal materials and in animal plasma using UPLC-Q-TOF/MS and were considered the potential active components of LGNXT. Thirty key targets and 57 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were identified as possible targets and pathways involved in LGNXT-mediated treatment using network pharmacology, with the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA)/Ca2+ system pathway being the most significantly affected. This finding was validated using an adrenaline (Adr)-induced rat model of arrhythmias. Pretreatment with LGNXT delayed the occurrence, shortened the duration, and reduced the severity of arrhythmias. LGNXT exerted antiarrhythmic effects by inhibiting cAMP, PKA, CACNA1C, and RyR2. CONCLUSIONS The findings of this study revealed that preventing intracellular Ca2+ overload and maintaining intracellular Ca2+ homeostasis may be the primary mechanisms of LGNXT in alleviating arrhythmias. Thus, we suggest that the β-adrenergic receptor (AR)/cAMP/PKA/Ca2+ system signaling hub may constitute a promising molecular target for the development of novel antiarrhythmic therapeutic interventions. Additionally, we believe that the approach of investigation of the biological effects of a multi-herbal formula by the combination of metabolomics and network pharmacology, as used in this study, could serve as a systematic model for TCM research.
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Affiliation(s)
- Jinhong Chen
- Graduate School, Tianjin University of TCM, Tianjin 301617, China
| | - Zhichao Liu
- Graduate School, Tianjin University of TCM, Tianjin 301617, China
| | - Fangjun Deng
- Graduate School, Tianjin University of TCM, Tianjin 301617, China
| | - Jiayu Liang
- Graduate School, Tianjin University of TCM, Tianjin 301617, China
| | - Boya Fan
- Graduate School, Tianjin University of TCM, Tianjin 301617, China
| | - Xin Zhen
- Graduate School, Tianjin University of TCM, Tianjin 301617, China
| | - Rui Tao
- Department of TCM, Tianjin University of TCM, Tianjin, 301617, China
| | - Lili Sun
- Department of TCM, Tianjin University of TCM, Tianjin, 301617, China
| | - Shaoqiang Zhang
- Department of Cardiology, The Second Affiliated Hospital of Tianjin University of TCM, Tianjin 300150, China
| | - Zidong Cong
- Department of Cardiology, The Second Affiliated Hospital of Tianjin University of TCM, Tianjin 300150, China
| | - Xiaofeng Li
- Department of Cardiology, The Second Affiliated Hospital of Tianjin University of TCM, Tianjin 300150, China.
| | - Wuxun Du
- Department of Cardiology, The Second Affiliated Hospital of Tianjin University of TCM, Tianjin 300150, China.
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8
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Mitochondrial Ca 2+ Homeostasis: Emerging Roles and Clinical Significance in Cardiac Remodeling. Int J Mol Sci 2022; 23:ijms23063025. [PMID: 35328444 PMCID: PMC8954803 DOI: 10.3390/ijms23063025] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/01/2022] [Accepted: 03/03/2022] [Indexed: 01/27/2023] Open
Abstract
Mitochondria are the sites of oxidative metabolism in eukaryotes where the metabolites of sugars, fats, and amino acids are oxidized to harvest energy. Notably, mitochondria store Ca2+ and work in synergy with organelles such as the endoplasmic reticulum and extracellular matrix to control the dynamic balance of Ca2+ concentration in cells. Mitochondria are the vital organelles in heart tissue. Mitochondrial Ca2+ homeostasis is particularly important for maintaining the physiological and pathological mechanisms of the heart. Mitochondrial Ca2+ homeostasis plays a key role in the regulation of cardiac energy metabolism, mechanisms of death, oxygen free radical production, and autophagy. The imbalance of mitochondrial Ca2+ balance is closely associated with cardiac remodeling. The mitochondrial Ca2+ uniporter (mtCU) protein complex is responsible for the uptake and release of mitochondrial Ca2+ and regulation of Ca2+ homeostasis in mitochondria and consequently, in cells. This review summarizes the mechanisms of mitochondrial Ca2+ homeostasis in physiological and pathological cardiac remodeling and the regulatory effects of the mitochondrial calcium regulatory complex on cardiac energy metabolism, cell death, and autophagy, and also provides the theoretical basis for mitochondrial Ca2+ as a novel target for the treatment of cardiovascular diseases.
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9
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Gaburjakova J, Gaburjakova M. The Cardiac Ryanodine Receptor Provides a Suitable Pathway for the Rapid Transport of Zinc (Zn2+). Cells 2022; 11:cells11050868. [PMID: 35269490 PMCID: PMC8909583 DOI: 10.3390/cells11050868] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 02/25/2022] [Accepted: 03/01/2022] [Indexed: 12/13/2022] Open
Abstract
The sarcoplasmic reticulum (SR) in cardiac muscle is suggested to act as a dynamic storage for Zn2+ release and reuptake, albeit it is primarily implicated in the Ca2+ signaling required for the cardiac cycle. A large Ca2+ release from the SR is mediated by the cardiac ryanodine receptor (RYR2), and while this has a prominent conductance for Ca2+ in vivo, it also conducts other divalent cations in vitro. Since Zn2+ and permeant Mg2+ have similar physical properties, we tested if the RYR2 channel also conducts Zn2+. Using the method of planar lipid membranes, we evidenced that the RYR2 channel is permeable to Zn2+ with a considerable conductance of 81.1 ± 2.4 pS, which was significantly lower than the values for Ca2+ (127.5 ± 1.8 pS) and Mg2+ (95.3 ± 1.4 pS), obtained under the same asymmetric conditions. Despite similar physical properties, the intrinsic Zn2+ permeability (PCa/PZn = 2.65 ± 0.19) was found to be ~2.3-fold lower than that of Mg2+ (PCa/PMg = 1.146 ± 0.071). Further, we assessed whether the channel itself could be a direct target of the Zn2+ current, having the Zn2+ finger extended into the cytosolic vestibular portion of the permeation pathway. We attempted to displace Zn2+ from the RYR2 Zn2+ finger to induce its structural defects, which are associated with RYR2 dysfunction. Zn2+ chelators were added to the channel cytosolic side or strongly competing cadmium cations (Cd2+) were allowed to permeate the RYR2 channel. Only the Cd2+ current was able to cause the decay of channel activity, presumably as a result of Zn2+ to Cd2+ replacement. Our findings suggest that the RYR2 channel can provide a suitable pathway for rapid Zn2+ escape from the cardiac SR; thus, the channel may play a role in local and/or global Zn2+ signaling in cardiomyocytes.
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10
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Gaburjáková M, Gaburjáková J, Krejčíová E, Kosnáč D, Kosnáčová H, Nagy Š, Polák Š, Sabo M, Trnka M, Kopáni M. Blocking effect of ferritin on the ryanodine receptor-isoform 2. Arch Biochem Biophys 2021; 712:109031. [PMID: 34534540 DOI: 10.1016/j.abb.2021.109031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/08/2021] [Accepted: 09/08/2021] [Indexed: 10/20/2022]
Abstract
Iron, an essential element for most living organism, participates in a wide variety of physiological processes. Disturbance in iron homeostasis has been associated with numerous pathologies, particularly in the heart and brain, which are the most susceptible organs. Under iron-overload conditions, the generation of reactive oxygen species leads to impairment in Ca2+ signaling, fundamentally implicated in cardiac and neuronal physiology. Since iron excess is accompanied by increased expression of iron-storage protein, ferritin, we examined whether ferritin has an effect on the ryanodine receptor - isoform 2 (RYR2), which is one of the major components of Ca2+ signaling. Using the method of planar lipid membranes, we show that ferritin induced an abrupt, permanent blockage of the RYR2 channel. The ferritin effect was strongly voltage dependent and competitively antagonized by cytosolic TEA+, an impermeant RYR2 blocker. Our results collectively indicate that monomeric ferritin highly likely blocks the RYR2 channel by a direct electrostatic interaction within the wider region of the channel permeation pathway.
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Affiliation(s)
- Marta Gaburjáková
- Centre of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Jana Gaburjáková
- Centre of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Eva Krejčíová
- Centre of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Daniel Kosnáč
- Institute of Medical Physics, Biophysics, Informatics and Telemedicine, Faculty of Medicine, Comenius University, Bratislava, Slovakia; Department of Simulation and Virtual Medical Education, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Helena Kosnáčová
- Department of Simulation and Virtual Medical Education, Faculty of Medicine, Comenius University, Bratislava, Slovakia; Slovak Academy of Sciences, Department of Genetics, Cancer Research Institute, Biomedical Research Center, Bratislava, Slovakia
| | - Štefan Nagy
- Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Štefan Polák
- Institute of Histology and Embryology, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Michal Sabo
- Institute of Medical Physics, Biophysics, Informatics and Telemedicine, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Michal Trnka
- Institute of Medical Physics, Biophysics, Informatics and Telemedicine, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Martin Kopáni
- Institute of Medical Physics, Biophysics, Informatics and Telemedicine, Faculty of Medicine, Comenius University, Bratislava, Slovakia.
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Hutchings DC, Pearman CM, Madders GWP, Woods LS, Eisner DA, Dibb KM, Trafford AW. PDE5 Inhibition Suppresses Ventricular Arrhythmias by Reducing SR Ca 2+ Content. Circ Res 2021; 129:650-665. [PMID: 34247494 PMCID: PMC8409902 DOI: 10.1161/circresaha.121.318473] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
[Figure: see text].
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Affiliation(s)
- David C Hutchings
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, United Kingdom
| | - Charles M Pearman
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, United Kingdom
| | - George W P Madders
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, United Kingdom
| | - Lori S Woods
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, United Kingdom
| | - David A Eisner
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, United Kingdom
| | - Katharine M Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, United Kingdom
| | - Andrew W Trafford
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Faculty of Biology Medicine and Health, University of Manchester, Manchester Academic Health Sciences Centre, United Kingdom
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12
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Woll KA, Van Petegem F. Calcium Release Channels: Structure and Function of IP3 Receptors and Ryanodine Receptors. Physiol Rev 2021; 102:209-268. [PMID: 34280054 DOI: 10.1152/physrev.00033.2020] [Citation(s) in RCA: 87] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ca2+-release channels are giant membrane proteins that control the release of Ca2+ from the endoplasmic and sarcoplasmic reticulum. The two members, ryanodine receptors (RyRs) and inositol-1,4,5-trisphosphate Receptors (IP3Rs), are evolutionarily related and are both activated by cytosolic Ca2+. They share a common architecture, but RyRs have evolved additional modules in the cytosolic region. Their massive size allows for the regulation by tens of proteins and small molecules, which can affect the opening and closing of the channels. In addition to Ca2+, other major triggers include IP3 for the IP3Rs, and depolarization of the plasma membrane for a particular RyR subtype. Their size has made them popular targets for study via electron microscopic methods, with current structures culminating near 3Å. The available structures have provided many new mechanistic insights int the binding of auxiliary proteins and small molecules, how these can regulate channel opening, and the mechanisms of disease-associated mutations. They also help scrutinize previously proposed binding sites, as some of these are now incompatible with the structures. Many questions remain around the structural effects of post-translational modifications, additional binding partners, and the higher-order complexes these channels can make in situ. This review summarizes our current knowledge about the structures of Ca2+-release channels and how this informs on their function.
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Affiliation(s)
- Kellie A Woll
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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13
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Protasi F, Pietrangelo L, Boncompagni S. Improper Remodeling of Organelles Deputed to Ca 2+ Handling and Aerobic ATP Production Underlies Muscle Dysfunction in Ageing. Int J Mol Sci 2021; 22:6195. [PMID: 34201319 PMCID: PMC8228829 DOI: 10.3390/ijms22126195] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/28/2022] Open
Abstract
Proper skeletal muscle function is controlled by intracellular Ca2+ concentration and by efficient production of energy (ATP), which, in turn, depend on: (a) the release and re-uptake of Ca2+ from sarcoplasmic-reticulum (SR) during excitation-contraction (EC) coupling, which controls the contraction and relaxation of sarcomeres; (b) the uptake of Ca2+ into the mitochondrial matrix, which stimulates aerobic ATP production; and finally (c) the entry of Ca2+ from the extracellular space via store-operated Ca2+ entry (SOCE), a mechanism that is important to limit/delay muscle fatigue. Abnormalities in Ca2+ handling underlie many physio-pathological conditions, including dysfunction in ageing. The specific focus of this review is to discuss the importance of the proper architecture of organelles and membrane systems involved in the mechanisms introduced above for the correct skeletal muscle function. We reviewed the existing literature about EC coupling, mitochondrial Ca2+ uptake, SOCE and about the structural membranes and organelles deputed to those functions and finally, we summarized the data collected in different, but complementary, projects studying changes caused by denervation and ageing to the structure and positioning of those organelles: a. denervation of muscle fibers-an event that contributes, to some degree, to muscle loss in ageing (known as sarcopenia)-causes misplacement and damage: (i) of membrane structures involved in EC coupling (calcium release units, CRUs) and (ii) of the mitochondrial network; b. sedentary ageing causes partial disarray/damage of CRUs and of calcium entry units (CEUs, structures involved in SOCE) and loss/misplacement of mitochondria; c. functional electrical stimulation (FES) and regular exercise promote the rescue/maintenance of the proper architecture of CRUs, CEUs, and of mitochondria in both denervation and ageing. All these structural changes were accompanied by related functional changes, i.e., loss/decay in function caused by denervation and ageing, and improved function following FES or exercise. These data suggest that the integrity and proper disposition of intracellular organelles deputed to Ca2+ handling and aerobic generation of ATP is challenged by inactivity (or reduced activity); modifications in the architecture of these intracellular membrane systems may contribute to muscle dysfunction in ageing and sarcopenia.
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Affiliation(s)
- Feliciano Protasi
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Laura Pietrangelo
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DMSI, Department of Medicine and Aging Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
| | - Simona Boncompagni
- CAST, Center for Advanced Studies and Technology, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy; (L.P.); (S.B.)
- DNICS, Department of Neuroscience and Clinical Sciences, University G. d’Annunzio of Chieti-Pescara, I-66100 Chieti, Italy
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14
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Mechanisms and Regulation of Cardiac Ca V1.2 Trafficking. Int J Mol Sci 2021; 22:ijms22115927. [PMID: 34072954 PMCID: PMC8197997 DOI: 10.3390/ijms22115927] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 05/28/2021] [Accepted: 05/29/2021] [Indexed: 01/05/2023] Open
Abstract
During cardiac excitation contraction coupling, the arrival of an action potential at the ventricular myocardium triggers voltage-dependent L-type Ca2+ (CaV1.2) channels in individual myocytes to open briefly. The level of this Ca2+ influx tunes the amplitude of Ca2+-induced Ca2+ release from ryanodine receptors (RyR2) on the junctional sarcoplasmic reticulum and thus the magnitude of the elevation in intracellular Ca2+ concentration and ultimately the downstream contraction. The number and activity of functional CaV1.2 channels at the t-tubule dyads dictates the amplitude of the Ca2+ influx. Trafficking of these channels and their auxiliary subunits to the cell surface is thus tightly controlled and regulated to ensure adequate sarcolemmal expression to sustain this critical process. To that end, recent discoveries have revealed the existence of internal reservoirs of preformed CaV1.2 channels that can be rapidly mobilized to enhance sarcolemmal expression in times of acute stress when hemodynamic and metabolic demand increases. In this review, we provide an overview of the current thinking on CaV1.2 channel trafficking dynamics in the heart. We highlight the numerous points of control including the biosynthetic pathway, the endosomal recycling pathway, ubiquitination, and lysosomal and proteasomal degradation pathways, and discuss the effects of β-adrenergic and angiotensin receptor signaling cascades on this process.
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15
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Evolutionary Aspects of TRPMLs and TPCs. Int J Mol Sci 2020; 21:ijms21114181. [PMID: 32545371 PMCID: PMC7312350 DOI: 10.3390/ijms21114181] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/05/2020] [Accepted: 06/10/2020] [Indexed: 01/02/2023] Open
Abstract
Transient receptor potential (TRP) or transient receptor potential channels are a highly diverse family of mostly non-selective cation channels. In the mammalian genome, 28 members can be identified, most of them being expressed predominantly in the plasma membrane with the exception of the mucolipins or TRPMLs which are expressed in the endo-lysosomal system. In mammalian organisms, TRPMLs have been associated with a number of critical endo-lysosomal functions such as autophagy, endo-lysosomal fusion/fission and trafficking, lysosomal exocytosis, pH regulation, or lysosomal motility and positioning. The related non-selective two-pore cation channels (TPCs), likewise expressed in endosomes and lysosomes, have also been found to be associated with endo-lysosomal trafficking, autophagy, pH regulation, or lysosomal exocytosis, raising the question why these two channel families have evolved independently. We followed TRP/TRPML channels and TPCs through evolution and describe here in which species TRP/TRPMLs and/or TPCs are found, which functions they have in different species, and how this compares to the functions of mammalian orthologs.
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16
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Kong CHT, Bryant SM, Watson JJ, Roth DM, Patel HH, Cannell MB, James AF, Orchard CH. Cardiac-specific overexpression of caveolin-3 preserves t-tubular I Ca during heart failure in mice. Exp Physiol 2019; 104:654-666. [PMID: 30786093 PMCID: PMC6488395 DOI: 10.1113/ep087304] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 02/18/2019] [Indexed: 12/17/2022]
Abstract
NEW FINDINGS What is the central question of this study? What is the cellular basis of the protection conferred on the heart by overexpression of caveolin-3 (Cav-3 OE) against many of the features of heart failure normally observed in vivo? What is the main finding and its importance? Cav-3 overexpression has little effect in normal ventricular myocytes but reduces cellular hypertrophy and preserves t-tubular ICa , but not local t-tubular Ca2+ release, in heart failure induced by pressure overload in mice. Thus Cav-3 overexpression provides specific but limited protection following induction of heart failure, although other factors disrupt Ca2+ release. ABSTRACT Caveolin-3 (Cav-3) is an 18 kDa protein that has been implicated in t-tubule formation and function in cardiac ventricular myocytes. During cardiac hypertrophy and failure, Cav-3 expression decreases, t-tubule structure is disrupted and excitation-contraction coupling (ECC) is impaired. Previous work has suggested that Cav-3 overexpression (OE) is cardio-protective, but the effect of Cav-3 OE on these cellular changes is unknown. We therefore investigated whether Cav-3 OE in mice is protective against the cellular effects of pressure overload induced by 8 weeks' transverse aortic constriction (TAC). Cav-3 OE mice developed cardiac dilatation, decreased stroke volume and ejection fraction, and hypertrophy and pulmonary congestion in response to TAC. These changes were accompanied by cellular hypertrophy, a decrease in t-tubule regularity and density, and impaired local Ca2+ release at the t-tubules. However, the extent of cardiac and cellular hypertrophy was reduced in Cav-3 OE compared to WT mice, and t-tubular Ca2+ current (ICa ) density was maintained. These data suggest that Cav-3 OE helps prevent hypertrophy and loss of t-tubular ICa following TAC, but that other factors disrupt local Ca2+ release.
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Affiliation(s)
- Cherrie H. T. Kong
- School of PhysiologyPharmacology & NeuroscienceBiomedical Sciences BuildingUniversity of BristolBristolBS8 1TDUK
| | - Simon M. Bryant
- School of PhysiologyPharmacology & NeuroscienceBiomedical Sciences BuildingUniversity of BristolBristolBS8 1TDUK
| | - Judy J. Watson
- School of PhysiologyPharmacology & NeuroscienceBiomedical Sciences BuildingUniversity of BristolBristolBS8 1TDUK
| | - David M. Roth
- VA San Diego Healthcare System and Department of AnesthesiologyUniversity of CaliforniaSan Diego, La JollaCAUSA
| | - Hemal H. Patel
- VA San Diego Healthcare System and Department of AnesthesiologyUniversity of CaliforniaSan Diego, La JollaCAUSA
| | - Mark B. Cannell
- School of PhysiologyPharmacology & NeuroscienceBiomedical Sciences BuildingUniversity of BristolBristolBS8 1TDUK
| | - Andrew F. James
- School of PhysiologyPharmacology & NeuroscienceBiomedical Sciences BuildingUniversity of BristolBristolBS8 1TDUK
| | - Clive H. Orchard
- School of PhysiologyPharmacology & NeuroscienceBiomedical Sciences BuildingUniversity of BristolBristolBS8 1TDUK
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17
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Yang L, Katchman A, Kushner J, Kushnir A, Zakharov SI, Chen BX, Shuja Z, Subramanyam P, Liu G, Papa A, Roybal D, Pitt GS, Colecraft HM, Marx SO. Cardiac CaV1.2 channels require β subunits for β-adrenergic-mediated modulation but not trafficking. J Clin Invest 2019; 129:647-658. [PMID: 30422117 DOI: 10.1172/jci123878] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 11/06/2018] [Indexed: 01/01/2023] Open
Abstract
Ca2+ channel β-subunit interactions with pore-forming α-subunits are long-thought to be obligatory for channel trafficking to the cell surface and for tuning of basal biophysical properties in many tissues. Unexpectedly, we demonstrate that transgenic expression of mutant α1C subunits lacking capacity to bind CaVβ can traffic to the sarcolemma in adult cardiomyocytes in vivo and sustain normal excitation-contraction coupling. However, these β-less Ca2+ channels cannot be stimulated by β-adrenergic pathway agonists, and thus adrenergic augmentation of contractility is markedly impaired in isolated cardiomyocytes and in hearts. Similarly, viral-mediated expression of a β-subunit-sequestering peptide sharply curtailed β-adrenergic stimulation of WT Ca2+ channels, identifying an approach to specifically modulate β-adrenergic regulation of cardiac contractility. Our data demonstrate that β subunits are required for β-adrenergic regulation of CaV1.2 channels and positive inotropy in the heart, but are dispensable for CaV1.2 trafficking to the adult cardiomyocyte cell surface, and for basal function and excitation-contraction coupling.
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Affiliation(s)
- Lin Yang
- Division of Cardiology, Department of Medicine, Columbia University
| | | | - Jared Kushner
- Division of Cardiology, Department of Medicine, Columbia University
| | | | | | - Bi-Xing Chen
- Division of Cardiology, Department of Medicine, Columbia University
| | - Zunaira Shuja
- Department of Physiology and Cellular Biophysics, and
| | | | - Guoxia Liu
- Division of Cardiology, Department of Medicine, Columbia University
| | - Arianne Papa
- Department of Physiology and Cellular Biophysics, and
| | - Daniel Roybal
- Department of Pharmacology, Vagelos College of Physicians and Surgeons, New York, New York, USA
| | - Geoffrey S Pitt
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, New York, USA
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, and.,Department of Pharmacology, Vagelos College of Physicians and Surgeons, New York, New York, USA
| | - Steven O Marx
- Division of Cardiology, Department of Medicine, Columbia University.,Department of Pharmacology, Vagelos College of Physicians and Surgeons, New York, New York, USA
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18
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Arif S, Lai CH, Ramesh NI. Estimation of stochastic behaviour in cardiac myocytes: I. Ca 2+ movements inside the cytosol and sarcoplasmic reticulum on curvilinear domains. JRSM Cardiovasc Dis 2019; 8:2048004018822428. [PMID: 30643637 PMCID: PMC6322098 DOI: 10.1177/2048004018822428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 07/06/2018] [Accepted: 11/13/2018] [Indexed: 11/15/2022] Open
Abstract
Since the discovery of Ca2+ sparks and their stochastic behaviour in cardiac myocytes, models have focused on the inclusion of stochasticity in their studies. While most models pay much attention to the stochastic modelling of cytosolic Ca2+ concentration the coupling of Ca2+ sparks and blinks in a stochastic model has not been explored fully. The cell morphology in in silico studies in the past is assumed to be Cartesian, spherical or cylindrical. The application on curvilinear grids can easily address certain restrictions posed by such grid set up and provide more realistic cell morphology. In this paper, we present a stochastic reaction-diffusion model that couples Ca2+ sparks and blinks in realistic shapes of cells in curvilinear domains. Methodology: Transformation of the model was performed to the curvilinear coordinate system. The set of equations is used to produce Ca2+ waves initiated from sparks and blinks. A non-buffered and non-dyed version as well as a buffered and dyed version of these equations were studied in light of observing the dynamics on the two different systems. For comparison, results for both the Cartesian and curvilinear grids are provided. Results and conclusions: A successful demonstration of the application of curvilinear grids serving as basis for future developments.
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Affiliation(s)
- Serife Arif
- Department of Mathematical Sciences, Faculty of Architecture, Computing and Humanities University of Greenwich, London, UK
| | - Choi-Hong Lai
- Department of Mathematical Sciences, Faculty of Architecture, Computing and Humanities University of Greenwich, London, UK
| | - Nadarajah I Ramesh
- Department of Mathematical Sciences, Faculty of Architecture, Computing and Humanities University of Greenwich, London, UK
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19
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Tammineni ER, Carrillo ED, Soto-Acosta R, Angel-Ambrocio AH, García MC, Bautista-Carbajal P, del Angel RM, Sánchez JA. The β
4
subunit of Ca
v
1.2 channels is required for an optimal interferon response in cardiac muscle cells. Sci Signal 2018; 11:11/560/eaaj1676. [DOI: 10.1126/scisignal.aaj1676] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Eshwar R. Tammineni
- Departamento de Farmacología, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - Elba D. Carrillo
- Departamento de Farmacología, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - Rubén Soto-Acosta
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - Antonio H. Angel-Ambrocio
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - María C. García
- Departamento de Farmacología, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - Patricia Bautista-Carbajal
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - Rosa M. del Angel
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - Jorge A. Sánchez
- Departamento de Farmacología, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
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20
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Bryant SM, Kong CHT, Watson JJ, Gadeberg HC, Roth DM, Patel HH, Cannell MB, James AF, Orchard CH. Caveolin-3 KO disrupts t-tubule structure and decreases t-tubular I Ca density in mouse ventricular myocytes. Am J Physiol Heart Circ Physiol 2018; 315:H1101-H1111. [PMID: 30028203 PMCID: PMC6415741 DOI: 10.1152/ajpheart.00209.2018] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 06/25/2018] [Accepted: 07/11/2018] [Indexed: 02/06/2023]
Abstract
Caveolin-3 (Cav-3) is a protein that has been implicated in t-tubule formation and function in cardiac ventricular myocytes. In cardiac hypertrophy and failure, Cav-3 expression decreases, t-tubule structure is disrupted, and excitation-contraction coupling is impaired. However, the extent to which the decrease in Cav-3 expression underlies these changes is unclear. We therefore investigated the structure and function of myocytes isolated from the hearts of Cav-3 knockout (KO) mice. These mice showed cardiac dilatation and decreased ejection fraction in vivo compared with wild-type control mice. Isolated KO myocytes showed cellular hypertrophy, altered t-tubule structure, and decreased L-type Ca2+ channel current ( ICa) density. This decrease in density occurred predominantly in the t-tubules, with no change in total ICa, and was therefore a consequence of the increase in membrane area. Cav-3 KO had no effect on L-type Ca2+ channel expression, and C3SD peptide, which mimics the scaffolding domain of Cav-3, had no effect on ICa in KO myocytes. However, inhibition of PKA using H-89 decreased ICa at the surface and t-tubule membranes in both KO and wild-type myocytes. Cav-3 KO had no significant effect on Na+/Ca2+ exchanger current or Ca2+ release. These data suggest that Cav-3 KO causes cellular hypertrophy, thereby decreasing t-tubular ICa density. NEW & NOTEWORTHY Caveolin-3 (Cav-3) is a protein that inhibits hypertrophic pathways, has been implicated in the formation and function of cardiac t-tubules, and shows decreased expression in heart failure. This study demonstrates that Cav-3 knockout mice show cardiac dysfunction in vivo, while isolated ventricular myocytes show cellular hypertrophy, changes in t-tubule structure, and decreased t-tubular L-type Ca2+ current density, suggesting that decreased Cav-3 expression contributes to these changes in cardiac hypertrophy and failure.
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MESH Headings
- Action Potentials
- Animals
- Calcium Channels, L-Type/metabolism
- Calcium Signaling
- Caveolin 3/deficiency
- Caveolin 3/genetics
- Down-Regulation
- Genetic Predisposition to Disease
- Heart Ventricles/metabolism
- Heart Ventricles/pathology
- Hypertrophy, Left Ventricular/genetics
- Hypertrophy, Left Ventricular/metabolism
- Hypertrophy, Left Ventricular/pathology
- Hypertrophy, Left Ventricular/physiopathology
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Phenotype
- Ventricular Dysfunction, Left/genetics
- Ventricular Dysfunction, Left/metabolism
- Ventricular Dysfunction, Left/pathology
- Ventricular Dysfunction, Left/physiopathology
- Ventricular Function, Left
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Affiliation(s)
- Simon M Bryant
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol , Bristol , United Kingdom
| | - Cherrie H T Kong
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol , Bristol , United Kingdom
| | - Judy J Watson
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol , Bristol , United Kingdom
| | - Hanne C Gadeberg
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol , Bristol , United Kingdom
| | - David M Roth
- Veterans Affairs San Diego Healthcare System and Department of Anesthesiology, University of California-San Diego , La Jolla, California
| | - Hemal H Patel
- Veterans Affairs San Diego Healthcare System and Department of Anesthesiology, University of California-San Diego , La Jolla, California
| | - Mark B Cannell
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol , Bristol , United Kingdom
| | - Andrew F James
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol , Bristol , United Kingdom
| | - Clive H Orchard
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol , Bristol , United Kingdom
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21
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Laver DR. Regulation of the RyR channel gating by Ca 2+ and Mg 2. Biophys Rev 2018; 10:1087-1095. [PMID: 29926426 PMCID: PMC6082316 DOI: 10.1007/s12551-018-0433-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 06/06/2018] [Indexed: 12/21/2022] Open
Abstract
Ryanodine receptors (RyRs) are the Ca2+ release channels in the sarcoplasmic reticulum in striated muscle which play an important role in excitation-contraction coupling and cardiac pacemaking. Single channel recordings have revealed a wealth of information about ligand regulation of RyRs from mammalian skeletal and cardiac muscle (RyR1 and RyR2, respectively). RyR subunit has a Ca2+ activation site located in the luminal and cytoplasmic domains of the RyR. These sites synergistically feed into a common gating mechanism for channel activation by luminal and cytoplasmic Ca2+. RyRs also possess two inhibitory sites in their cytoplasmic domains with Ca2+ affinities of the order of 1 μM and 1 mM. Magnesium competes with Ca2+ at these sites to inhibit RyRs and this plays an important role in modulating their Ca2+-dependent activity in muscle. This review focuses on how these sites lead to RyR modulation by Ca2+ and Mg2+ and how these mechanisms control Ca2+ release in excitation-contraction coupling and cardiac pacemaking.
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Affiliation(s)
- Derek R Laver
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW, 2308, Australia.
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22
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Hedrich R, Mueller TD, Becker D, Marten I. Structure and Function of TPC1 Vacuole SV Channel Gains Shape. MOLECULAR PLANT 2018; 11:764-775. [PMID: 29614320 DOI: 10.1016/j.molp.2018.03.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 03/12/2018] [Accepted: 03/22/2018] [Indexed: 05/20/2023]
Abstract
Plants and animals in endosomes operate TPC1/SV-type cation channels. All plants harbor at least one TPC1 gene. Although the encoded SV channel was firstly discovered in the plant vacuole membrane two decades ago, its biological function has remained enigmatic. Recently, the structure of a plant TPC1/SV channel protein was determined. Insights into the 3D topology has now guided site-directed mutation approaches, enabling structure-function analyses of TPC1/SV channels to shed new light on earlier findings. Fou2 plants carrying a hyperactive mutant form of TPC1 develop wounding stress phenotypes. Recent studies with fou2 and mutants that lack functional TPC1 have revealed atypical features in local and long-distance stress signaling, providing new access to the previously mysterious biology of this vacuolar cation channel type in planta.
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Affiliation(s)
- Rainer Hedrich
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany.
| | - Thomas D Mueller
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - Dirk Becker
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
| | - Irene Marten
- Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, Julius-von-Sachs Platz 2, 97082 Würzburg, Germany
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23
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Abstract
Ryanodine-sensitive intracellular Ca2+ channels (RyRs) open upon binding Ca2+ at cytosolic-facing sites. This results in concerted, self-reinforcing opening of RyRs clustered in specialized regions on the membranes of Ca2+ storage organelles (endoplasmic reticulum and sarcoplasmic reticulum), a process that produces Ca2+-induced Ca2+ release (CICR). The process is optimized to achieve large but brief and localized increases in cytosolic Ca2+ concentration, a feature now believed to be critical for encoding the multiplicity of signals conveyed by this ion. In this paper, I trace the path of research that led to a consensus on the physiological significance of CICR in skeletal muscle, beginning with its discovery. I focus on the approaches that were developed to quantify the contribution of CICR to the Ca2+ increase that results in contraction, as opposed to the flux activated directly by membrane depolarization (depolarization-induced Ca2+ release [DICR]). Although the emerging consensus is that CICR plays an important role alongside DICR in most taxa, its contribution in most mammalian muscles appears to be limited to embryogenesis. Finally, I survey the relevance of CICR, confirmed or plausible, to pathogenesis as well as the multiple questions about activation of release channels that remain unanswered after 50 years.
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Affiliation(s)
- Eduardo Ríos
- Section of Cellular Signaling, Department of Physiology and Biophysics, Rush University School of Medicine, Chicago, IL
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24
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Matsuki K, Kato D, Takemoto M, Suzuki Y, Yamamura H, Ohya S, Takeshima H, Imaizumi Y. Negative regulation of cellular Ca 2+ mobilization by ryanodine receptor type 3 in mouse mesenteric artery smooth muscle. Am J Physiol Cell Physiol 2018. [PMID: 29537866 DOI: 10.1152/ajpcell.00006.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Physiological functions of type 3 ryanodine receptors (RyR3) in smooth muscle (SM) tissues are not well understood, in spite of their wide expression. However, the short isoform of RyR3 is known to be a dominant-negative variant (DN-RyR3), which may negatively regulate functions of both RyR2 and full-length (FL) RyR3 by forming hetero-tetramers. Here, functional roles of RyR3 in the regulation of Ca2+ signaling in mesenteric artery SM cells (MASMCs) were examined using RyR3 homozygous knockout mice (RyR3-/-). Quantitative PCR analyses suggested that the predominant RyR3 subtype in MASMs from wild-type mice (RyR3+/+) was DN-RyR3. In single MASMCs freshly isolated from RyR3-/-, the EC50 of caffeine to induce Ca2+ release was lower than that in RyR3+/+ myocytes. The amplitude and frequency of Ca2+ sparks and spontaneous transient outward currents in MASMCs from RyR3-/- were all larger than those from RyR3+/+. Importantly, mRNA and functional expressions of voltage-dependent Ca2+ channel and large-conductance Ca2+-activated K+ (BK) channel in MASMCs from RyR3-/- were identical to those from RyR3+/+. However, in the presence of BK channel inhibitor, paxilline, the pressure rises induced by BayK8644 in MA vascular beds of RyR3-/- were significantly larger than in those of RyR3+/+. This indicates that the negative feedback effects of BK channel activity on intracellular Ca2+ signaling was enhanced in RyR3-/-. Thus, RyR3, and, in fact, mainly DN-RyR3, via a complex with RyR2 suppresses Ca2+ release and indirectly regulated membrane potential by reducing BK channel activity in MASMCs and presumably can affect the regulation of intrinsic vascular tone.
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Affiliation(s)
- Katsuhito Matsuki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
| | - Daiki Kato
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
| | - Masashi Takemoto
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
| | - Yoshiaki Suzuki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
| | - Hisao Yamamura
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
| | - Susumu Ohya
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan.,Department of Pharmacology, Graduate School of Medicine, Nagoya City University , Nagoya , Japan
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University , Kyoto , Japan
| | - Yuji Imaizumi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University , Nagoya , Japan
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25
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Folkerts EJ, Blewett TA, He Y, Goss GG. Cardio-respirometry disruption in zebrafish (Danio rerio) embryos exposed to hydraulic fracturing flowback and produced water. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2017; 231:1477-1487. [PMID: 28928018 DOI: 10.1016/j.envpol.2017.09.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 08/31/2017] [Accepted: 09/06/2017] [Indexed: 05/23/2023]
Abstract
Hydraulic fracturing to extract oil and natural gas reserves is an increasing practice in many international energy sectors. Hydraulic fracturing flowback and produced water (FPW) is a hyper saline wastewater returned to the surface from a fractured well containing chemical species present in the initial fracturing fluid, geogenic contaminants, and potentially newly synthesized chemicals formed in the fracturing well environment. However, information on FPW toxicological mechanisms of action remain largely unknown. Both cardiotoxic and respirometric responses were explored in zebrafish (Danio rerio) embryos after either an acute sediment-free (FPW-SF) or raw/sediment containing (FPW-S) fraction exposure of 24 and 48 h at 2.5% and 5% dilutions. A 48 h exposure to either FPW fraction in 24-72 h post fertilization zebrafish embryos significantly increased occurrences of pericardial edema, yolk-sac edema, and tail/spine curvature. In contrast, larval heart rates significantly decreased after FPW fraction exposures. FPW-S, but not FPW-SF, at 2.5% doses significantly reduced embryonic respiration/metabolic rates (MO2), while for 5% FPW, both fractions reduced MO2. Expression of select cardiac genes were also significantly altered in each FPW exposure group, implicating a cardiovascular system compromise as the potential cause for reduced embryonic MO2. Collectively, these results support our hypothesis that organics are major contributors to cardiac and respiratory responses to FPW exposure in zebrafish embryos. Our study is the first to investigate cardiac and respiratory sub-lethal effects of FPW exposure, demonstrating that FPW effects extend beyond initial osmotic stressors and verifies the use of respirometry as a potential marker for FPW exposure.
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Affiliation(s)
- Erik J Folkerts
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
| | - Tamzin A Blewett
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Yuhe He
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Greg G Goss
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada; National Institute for Nanotechnology, Edmonton, Alberta, Canada
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26
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Abstract
Cardiac contractility is regulated by changes in intracellular Ca concentration ([Ca2+]i). Normal function requires that [Ca2+]i be sufficiently high in systole and low in diastole. Much of the Ca needed for contraction comes from the sarcoplasmic reticulum and is released by the process of calcium-induced calcium release. The factors that regulate and fine-tune the initiation and termination of release are reviewed. The precise control of intracellular Ca cycling depends on the relationships between the various channels and pumps that are involved. We consider 2 aspects: (1) structural coupling: the transporters are organized within the dyad, linking the transverse tubule and sarcoplasmic reticulum and ensuring close proximity of Ca entry to sites of release. (2) Functional coupling: where the fluxes across all membranes must be balanced such that, in the steady state, Ca influx equals Ca efflux on every beat. The remainder of the review considers specific aspects of Ca signaling, including the role of Ca buffers, mitochondria, Ca leak, and regulation of diastolic [Ca2+]i.
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Affiliation(s)
- David A Eisner
- From the Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, United Kingdom.
| | - Jessica L Caldwell
- From the Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, United Kingdom
| | - Kornél Kistamás
- From the Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, United Kingdom
| | - Andrew W Trafford
- From the Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Sciences Centre, University of Manchester, United Kingdom
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27
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Gaburjakova M, Gaburjakova J. Insight towards the identification of cytosolic Ca 2+ -binding sites in ryanodine receptors from skeletal and cardiac muscle. Acta Physiol (Oxf) 2017; 219:757-767. [PMID: 27543850 DOI: 10.1111/apha.12772] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 07/13/2016] [Accepted: 08/12/2016] [Indexed: 11/30/2022]
Abstract
Ca2+ plays a critical role in several processes involved in skeletal and cardiac muscle contraction. One key step in cardiac excitation-contraction (E-C) coupling is the activation of the cardiac ryanodine receptor (RYR2) by cytosolic Ca2+ elevations. Although this process is not critical for skeletal E-C coupling, the activation and inhibition of the skeletal ryanodine receptor (RYR1) seem to be important for overall muscle function. The RYR1 and RYR2 channels fall within the large category of Ca2+ -binding proteins that harbour highly selective Ca2+ -binding sites to receive and translate the various Ca2+ signals into specific functional responses. However, little is known about the precise localization of these sites within the cytosolic assembly of both RYR isoforms, although several experimental lines of evidence have highlighted their EF-hand nature. EF-hand proteins share a common helix-loop-helix structural motif with highly conserved residues involved in Ca2+ coordination. The first step in predicting EF-hand positive regions is to compare the primary protein structure with the EF-hand motif by employing available bioinformatics tools. Although this simple method narrows down search regions, it does not provide solid evidence regarding which regions bind Ca2+ in both RYR isoforms. In this review, we seek to highlight the key findings and experimental approaches that should strengthen our future efforts to identify the cytosolic Ca2+ -binding sites responsible for activation and inhibition in the RYR1 channel, as much less work has been conducted on the RYR2 channel.
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Affiliation(s)
- M. Gaburjakova
- Institute of Molecular Physiology and Genetics; Slovak Academy of Sciences; Bratislava Slovak Republic
| | - J. Gaburjakova
- Institute of Molecular Physiology and Genetics; Slovak Academy of Sciences; Bratislava Slovak Republic
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28
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Davoodi M, Segal S, Kirschner Peretz N, Kamoun D, Yaniv Y. Semi-automated program for analysis of local Ca 2+ spark release with application for classification of heart cell type. Cell Calcium 2017; 64:83-90. [PMID: 28216082 DOI: 10.1016/j.ceca.2017.02.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 02/07/2017] [Accepted: 02/07/2017] [Indexed: 01/30/2023]
Abstract
Local Ca2+ spark releases are essential to the Ca2+ cycling process. Thus, they play an important role in ventricular and atrial cell contraction, as well as in sinoatrial cell automaticity. Characterizing their properties in healthy cells from different regions in the heart can reveal the basic biophysical differences among these regions. We designed a semi-automatic Matlab Graphical User Interface (called Sparkalyzer) to characterize parameters of Ca2+ spark release from any major cardiac tissue, as recorded in line-scan mode with a confocal laser-scanning microscope. We validated the algorithm on experimental images from rabbit sinoatrial, atrial, and ventricular cells loaded with Fluo-4 AM. The program characterizes general image parameters of Ca2+ transients and sparks: spark duration, which indicates for how long the spark provides Ca2+ to the closed intracellular mechanisms (typical value: 25±1, 23±1, 26±1ms for sinoatrial, atrial, and ventricular cells, respectively); spark amplitude, which indicates the amount of Ca2+ released by a single spark (1.6±0.1, 1.6±0.2, 1.4±0.1F/F0 for sinoatrial, atrial, and ventricular cells, respectively); spark length, which is the length of the Ca2+ wavelets fired out of a row of ryanodine receptors (5±0.1, 5±0.2, 3.4±0.3μm for sinoatrial, atrial, or ventricular cells, respectively) and number of sparks (0.14±0.02, 0.025±0.01, 0.02±0.01 for 1μm in 1s for sinoatrial, atrial, and ventricular cells, respectively). This method is reliable for Ca2+ spark analysis of sinoatrial, atrial, or ventricular cells. Moreover, by examining the average value of Ca2+ spark characteristics and their scattering around the mean, atrial, ventricular and sinoatrial cells can be differentiated.
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Affiliation(s)
- Moran Davoodi
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel
| | - Sofia Segal
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel
| | | | - David Kamoun
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel
| | - Yael Yaniv
- Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel.
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29
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Ryanodine receptor type 3 does not contribute to contractions in the mouse myometrium regardless of pregnancy. Pflugers Arch 2016; 469:313-326. [PMID: 27866274 DOI: 10.1007/s00424-016-1900-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/20/2016] [Accepted: 11/03/2016] [Indexed: 01/08/2023]
Abstract
Ryanodine receptor type 3 (RyR3) is expressed in myometrial smooth muscle cells (MSMCs). The short isoform of RyR3 is a dominant negative variant (DN-RyR3) and negatively regulates the functions of RyR2 and full-length (FL)-RyR3. DN-RyR3 has been suggested to function as a major RyR3 isoform in non-pregnant (NP) mouse MSMCs, and FL-RyR3 may also be upregulated during pregnancy (P). This increase in the FL-RyR3/DN-RyR3 ratio may contribute to the strong contractions by MSMCs for parturition. In the present study, spontaneous contractions by the myometrium in NP and P mice were highly susceptible to nifedipine but were not affected by ryanodine. Ca2+ image analyses under a voltage clamp revealed that the influx of Ca2+ through voltage-dependent Ca2+ channels did not cause the release of Ca2+ from the sarcoplasmic reticulum (SR). Cytosolic Ca2+ concentrations ([Ca2+]cyt) in MSMCs were not affected by caffeine. Despite the abundant expression of large conductance Ca2+-activated K+ channels in MSMCs, spontaneous transient outward currents were not observed in the resting state because of the substantive lack of Ca2+ sparks. Quantitative PCR and Western blot analyses indicated that DN-RyR3 was strongly expressed in the NP myometrium, while the expression of FL-RyR3 and DN-RyR3 was markedly reduced in the P myometrium. The messenger RNA (mRNA) expression of RyR2 and RyR1 was negligible in the NP and P myometria. Moreover, RyR3 knockout mice may become pregnant and deliver normally. Thus, we concluded that none of the RyR subtypes, including RyR3, play a significant role in the regulation of [Ca2+]cyt in or contractions by mouse MSMCs regardless of pregnancy.
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30
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Enhancement of contraction and L-type Ca2+ current by murrayafoline-A via protein kinase C in rat ventricular myocytes. Eur J Pharmacol 2016; 784:33-41. [DOI: 10.1016/j.ejphar.2016.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Revised: 04/30/2016] [Accepted: 05/04/2016] [Indexed: 11/17/2022]
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31
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Abstract
The aim of this review is to provide the reader with a synopsis of some of the emerging ideas and experimental findings in cardiac physiology and pathophysiology that were published in 2015. To provide context for the non-specialist, a brief summary of cardiac contraction and calcium (Ca) regulation in the heart in health and disease is provided. Thereafter, some recently published articles are introduced that indicate the current thinking on (1) the Ca regulatory pathways modulated by Ca/calmodulin-dependent protein kinase II, (2) the potential influences of nitrosylation by nitric oxide or S-nitrosated proteins, (3) newly observed effects of reactive oxygen species (ROS) on contraction and Ca regulation following myocardial infarction and a possible link with changes in mitochondrial Ca, and (4) the effects of some of these signaling pathways on late Na current and pro-arrhythmic afterdepolarizations as well as the effects of transverse tubule disturbances.
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Affiliation(s)
- Ken T MacLeod
- Faculty of Medicine, National Heart & Lung Institute, Imperial College London, London, UK
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32
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Boyden PA, Dun W, Stuyvers BD. What is a Ca(2+) wave? Is it like an Electrical Wave? Arrhythm Electrophysiol Rev 2016; 4:35-9. [PMID: 26835097 DOI: 10.15420/aer.2015.4.1.35] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 02/25/2015] [Indexed: 11/04/2022] Open
Abstract
Arrhythmia subcellular mechanisms are constantly being explored. Recent knowledge has shown that travelling Ca(2+) waves in cardiac cells are critical for delayed afterdepolarisations and in some cases, early afterdepolarisations. In this review, we comment on the properties of cardiac Ca(2+) waves and abnormal Ca(2+) releases in terms of properties used to describe electrical waves; propagation, excitability and refractoriness.
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Affiliation(s)
| | - Wen Dun
- Department of Pharmacology, Columbia University, New York
| | - Bruno D Stuyvers
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
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33
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Wong AY, Fabiato A, Bassingthwaighthe JB. Model of calcium-induced calcium release mechanism in cardiac cells. Bull Math Biol 2015; 54:95-116. [PMID: 25665663 DOI: 10.1007/bf02458622] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/1990] [Revised: 12/05/1990] [Indexed: 11/24/2022]
Abstract
A model with which to elucidate the mechanism of Ca(2+) release from, and Ca(2+) loading in the sarcoplasmic reticulum (SR) by Ca(2+) current (I Ca) in cardiac cells is proposed. The SR is assumed to be comprised of three functional subcompartments: (1) the main calcium store (MCS), which contains most of the calcium (both free and bound); (2) the releasable terminal (RT), which contains the calcium readily available for release; and (3) the longitudinal network of the SR (LSR), which sequesters and the transfers the sarcoplasmic calcium to the RT. A rapid increase of the Ca(2+) concentration at the outer surface of the SR (Cae) due to the fast component of I(Ca) activates and inactivates this surface, inducing the release of Ca(2+) from the RT to the sarcoplasmic space. The RT in turn is further activated and inactivated by a increase in the concentration of sarcoplasmic Ca(2+). The Ca(2+) in the sarcoplasmic space is then sequestered by the LSR, leading to the reactivation of the RT. Further increase of Cae due to the slow component of I(Ca) enhances the entry of Ca(2+) into the MCS to be bound by the binding substance. The free Ca(2+) released from the Ca-binding substance complex is transferred to the RT for subsequent release. The activation, inactivation and reactivation are Ca(2+)-mediated and time-dependent. The proposed model yields simulation of the many events qualitatively similar to those observed experimentally in skinned cardiac cells.
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Affiliation(s)
- A Y Wong
- Department of Physiology and Biophysics, Dalhousie University, B3H 4H7, Halifax, Nova Scotia, Canada
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34
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Son MJ, Chidipi B, Kim JC, Huong TT, Tai BH, Kim YH, Ahn JR, Cuong NM, Woo SH. Alterations of contractions and L-type Ca2+ currents by murrayafoline-A in rat ventricular myocytes. Eur J Pharmacol 2014; 740:81-7. [DOI: 10.1016/j.ejphar.2014.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 07/02/2014] [Accepted: 07/02/2014] [Indexed: 11/13/2022]
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35
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Effect of Ca2+ efflux pathway distribution and exogenous Ca2+ buffers on intracellular Ca2+ dynamics in the rat ventricular myocyte: a simulation study. BIOMED RESEARCH INTERNATIONAL 2014; 2014:920208. [PMID: 24971358 PMCID: PMC4058148 DOI: 10.1155/2014/920208] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 04/18/2014] [Accepted: 04/25/2014] [Indexed: 11/30/2022]
Abstract
We have used a previously published computer model of the rat cardiac ventricular myocyte to investigate the effect of changing the distribution of Ca2+ efflux pathways (SERCA, Na+/Ca2+ exchange, and sarcolemmal Ca2+ ATPase) between the dyad and bulk cytoplasm and the effect of adding exogenous Ca2+ buffers (BAPTA or EGTA), which are used experimentally to differentially buffer Ca2+ in the dyad and bulk cytoplasm, on cellular Ca2+ cycling. Increasing the dyadic fraction of a particular Ca2+ efflux pathway increases the amount of Ca2+ removed by that pathway, with corresponding changes in Ca2+ efflux from the bulk cytoplasm. The magnitude of these effects varies with the proportion of the total Ca2+ removed from the cytoplasm by that pathway. Differences in the response to EGTA and BAPTA, including changes in Ca2+-dependent inactivation of the L-type Ca2+ current, resulted from the buffers acting as slow and fast “shuttles,” respectively, removing Ca2+ from the dyadic space. The data suggest that complex changes in dyadic Ca2+ and cellular Ca2+ cycling occur as a result of changes in the location of Ca2+ removal pathways or the presence of exogenous Ca2+ buffers, although changing the distribution of Ca2+ efflux pathways has relatively small effects on the systolic Ca2+ transient.
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36
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Stoehr A, Neuber C, Baldauf C, Vollert I, Friedrich FW, Flenner F, Carrier L, Eder A, Schaaf S, Hirt MN, Aksehirlioglu B, Tong CW, Moretti A, Eschenhagen T, Hansen A. Automated analysis of contractile force and Ca2+ transients in engineered heart tissue. Am J Physiol Heart Circ Physiol 2014; 306:H1353-63. [PMID: 24585781 DOI: 10.1152/ajpheart.00705.2013] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Contraction and relaxation are fundamental aspects of cardiomyocyte functional biology. They reflect the response of the contractile machinery to the systolic increase and diastolic decrease of the cytoplasmic Ca(2+) concentration. The analysis of contractile function and Ca(2+) transients is therefore important to discriminate between myofilament responsiveness and changes in Ca(2+) homeostasis. This article describes an automated technology to perform sequential analysis of contractile force and Ca(2+) transients in up to 11 strip-format, fibrin-based rat, mouse, and human fura-2-loaded engineered heart tissues (EHTs) under perfusion and electrical stimulation. Measurements in EHTs under increasing concentrations of extracellular Ca(2+) and responses to isoprenaline and carbachol demonstrate that EHTs recapitulate basic principles of heart tissue functional biology. Ca(2+) concentration-response curves in rat, mouse, and human EHTs indicated different maximal twitch forces (0.22, 0.05, and 0.08 mN in rat, mouse, and human, respectively; P < 0.001) and different sensitivity to external Ca(2+) (EC50: 0.15, 0.39, and 1.05 mM Ca(2+) in rat, mouse, and human, respectively; P < 0.001) in the three groups. In contrast, no difference in myofilament Ca(2+) sensitivity was detected between skinned rat and human EHTs, suggesting that the difference in sensitivity to external Ca(2+) concentration is due to changes in Ca(2+) handling proteins. Finally, this study confirms that fura-2 has Ca(2+) buffering effects and is thereby changing the force response to extracellular Ca(2+).
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Affiliation(s)
- Andrea Stoehr
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Martinistraße, Hamburg, Germany
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37
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Bryant S, Kimura TE, Kong CHT, Watson JJ, Chase A, Suleiman MS, James AF, Orchard CH. Stimulation of ICa by basal PKA activity is facilitated by caveolin-3 in cardiac ventricular myocytes. J Mol Cell Cardiol 2014; 68:47-55. [PMID: 24412535 PMCID: PMC3980375 DOI: 10.1016/j.yjmcc.2013.12.026] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 12/22/2013] [Accepted: 12/31/2013] [Indexed: 12/14/2022]
Abstract
L-type Ca channels (LTCC), which play a key role in cardiac excitation–contraction coupling, are located predominantly at the transverse (t-) tubules in ventricular myocytes. Caveolae and the protein caveolin-3 (Cav-3) are also present at the t-tubules and have been implicated in localizing a number of signaling molecules, including protein kinase A (PKA) and β2-adrenoceptors. The present study investigated whether disruption of Cav-3 binding to its endogenous binding partners influenced LTCC activity. Ventricular myocytes were isolated from male Wistar rats and LTCC current (ICa) recorded using the whole-cell patch-clamp technique. Incubation of myocytes with a membrane-permeable peptide representing the scaffolding domain of Cav-3 (C3SD) reduced basal ICa amplitude in intact, but not detubulated, myocytes, and attenuated the stimulatory effects of the β2-adrenergic agonist zinterol on ICa. The PKA inhibitor H-89 also reduced basal ICa; however, the inhibitory effects of C3SD and H-89 on basal ICa amplitude were not summative. Under control conditions, myocytes stained with antibody against phosphorylated LTCC (pLTCC) displayed a striated pattern, presumably reflecting localization at the t-tubules. Both C3SD and H-89 reduced pLTCC staining at the z-lines but did not affect staining of total LTCC or Cav-3. These data are consistent with the idea that the effects of C3SD and H-89 share a common pathway, which involves PKA and is maximally inhibited by H-89, and suggest that Cav-3 plays an important role in mediating stimulation of ICa at the t-tubules via PKA-induced phosphorylation under basal conditions, and in response to β2-adrenoceptor stimulation. Basal L type calcium current was reduced by interfering with caveolin-3 binding. L type calcium current is tonically regulated by PKA phosphorylation. Interfering with caveolin-3 binding reduced beta2 adrenergic stimulation of ICa.
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Affiliation(s)
- Simon Bryant
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Tomomi E Kimura
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Cherrie H T Kong
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Judy J Watson
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Anabelle Chase
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - M Saadeh Suleiman
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK
| | - Andrew F James
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK.
| | - Clive H Orchard
- School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, UK.
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38
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Zhao Z, Gordan R, Wen H, Fefelova N, Zang WJ, Xie LH. Modulation of intracellular calcium waves and triggered activities by mitochondrial ca flux in mouse cardiomyocytes. PLoS One 2013; 8:e80574. [PMID: 24348912 PMCID: PMC3857829 DOI: 10.1371/journal.pone.0080574] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 10/04/2013] [Indexed: 12/23/2022] Open
Abstract
Recent studies have suggested that mitochondria may play important roles in the Ca(2+) homeostasis of cardiac myocytes. However, it is still unclear if mitochondrial Ca(2+) flux can regulate the generation of Ca(2+) waves (CaWs) and triggered activities in cardiac myocytes. In the present study, intracellular/cytosolic Ca(2+) (Cai (2+)) was imaged in Fluo-4-AM loaded mouse ventricular myocytes. Spontaneous sarcoplasmic reticulum (SR) Ca(2+) release and CaWs were induced in the presence of high (4 mM) external Ca(2+) (Cao (2+)). The protonophore carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) reversibly raised basal Cai (2+) levels even after depletion of SR Ca(2+) in the absence of Cao (2+) , suggesting Ca(2+) release from mitochondria. FCCP at 0.01 - 0.1 µM partially depolarized the mitochondrial membrane potential (Δψ m ) and increased the frequency and amplitude of CaWs in a dose-dependent manner. Simultaneous recording of cell membrane potentials showed the augmentation of delayed afterdepolarization amplitudes and frequencies, and induction of triggered action potentials. The effect of FCCP on CaWs was mimicked by antimycin A (an electron transport chain inhibitor disrupting Δψ m ) or Ru360 (a mitochondrial Ca(2+) uniporter inhibitor), but not by oligomycin (an ATP synthase inhibitor) or iodoacetic acid (a glycolytic inhibitor), excluding the contribution of intracellular ATP levels. The effects of FCCP on CaWs were counteracted by the mitochondrial permeability transition pore blocker cyclosporine A, or the mitochondrial Ca(2+) uniporter activator kaempferol. Our results suggest that mitochondrial Ca(2+) release and uptake exquisitely control the local Ca(2+) level in the micro-domain near SR ryanodine receptors and play an important role in regulation of intracellular CaWs and arrhythmogenesis.
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Affiliation(s)
- Zhenghang Zhao
- Department of Pharmacology, School of Medicine, Xi’an Jiaotong University, Xi’an, China
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
| | - Richard Gordan
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
| | - Hairuo Wen
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
- Department of Reproductive and Genetic Toxicology, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, P.R. China
| | - Nadezhda Fefelova
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
| | - Wei-Jin Zang
- Department of Pharmacology, School of Medicine, Xi’an Jiaotong University, Xi’an, China
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey, United States of America
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39
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Zhang Y, Huang L, Zuo Z, Chen Y, Wang C. Phenanthrene exposure causes cardiac arrhythmia in embryonic zebrafish via perturbing calcium handling. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 142-143:26-32. [PMID: 23948075 DOI: 10.1016/j.aquatox.2013.07.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 07/18/2013] [Accepted: 07/19/2013] [Indexed: 06/02/2023]
Abstract
Phenanthrene (Phe) is one of the most abundant and ubiquitous polycyclic aromatic hydrocarbons in the aquatic environment. It is known that Phe has cardiotoxic effects, but knowledge concerning the mechanism of cardiac dysfunction caused by Phe is still limited. In this study, zebrafish embryos were exposed to environmentally relevant concentrations of Phe, and an increase of an irregular rhythm was observed in Phe treated embryos. Disordered calcium (Ca(2+)) handling characterized by impaired sarcoplasmic reticulum Ca(2+) uptake, and obvious Ca(2+) accumulation in the cytoplasm was observed in rat embryonic cardiac myoblasts (H9C2) exposed to Phe. The mRNA level as well as protein expression of the SERCA2a Ca(2+) pump in zebrafish hearts or H9C2 cells was significantly decreased by Phe exposure. The activity of Ca(2+)-ATPase in H9C2 cells was inhibited by Phe. Both the mRNA and protein levels of TBX5, a direct regulator of SERCA2a, were significantly decreased by Phe exposure. These results suggested that exposure to Phe could lead to arrhythmia in zebrafish embryos via perturbing the calcium handling pathway.
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Affiliation(s)
- Youyu Zhang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, PR China
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Greensmith DJ, Nirmalan M. The effects of tumor necrosis factor-alpha on systolic and diastolic function in rat ventricular myocytes. Physiol Rep 2013; 1:e00093. [PMID: 24303157 PMCID: PMC3831905 DOI: 10.1002/phy2.93] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 08/14/2013] [Accepted: 08/15/2013] [Indexed: 11/20/2022] Open
Abstract
The proinflammatory cytokine tumor necrosis factor-alpha (TNF-α) is associated with myocardial dysfunction observed in sepsis and septic shock. There are two fundamental components to this dysfunction. (1) systolic dysfunction; and (2) diastolic dysfunction. The aim of these experiments was to determine if any aspect of whole-heart dysfunction could be explained by alterations to global intracellular calcium ([Ca2+]i), contractility, and [Ca2+]i handling, by TNF-α, at the level of the individual rat myocyte. We took an integrative approach to simultaneously measure [Ca2+]i, contractility and sarcolemmal Ca fluxes using the Ca indicator fluo-3, video edge detection, and the perforated patch technique, respectively. All experiments were performed at 37°C. The effects of 50 ng/mL TNF-α were immediate and sustained. The amplitude of systolic [Ca2+]i was reduced by 31% and systolic shortening by 19%. Diastolic [Ca2+]i, myocyte length and relaxation rate were not affected, nor were the activity of the [Ca2+]i removal mechanisms. The reduction in systolic [Ca2+]i was associated with a 14% reduction in sarcoplasmic reticulum (SR) content and a 11% decrease in peak L-type Ca current (ICa-L). Ca influx was decreased by 7% associated with a more rapid ICa-L inactivation. These data show that at the level of the myocyte, TNF-α reduces SR Ca which underlies a reduction in systolic [Ca2+]i and thence shortening. Although these findings correlate well with aspects of systolic myocardial dysfunction seen in sepsis, in this model, acutely, TNF-α does not appear to provide a cellular mechanism for sepsis-related diastolic myocardial dysfunction.
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Affiliation(s)
- David J Greensmith
- Unit of Cardiac Physiology, Institute of Cardiovascular Science, Manchester Academic Health Science Centre, Core Technology Facility 46 Grafton Street, Manchester, M13 9NT, U.K
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Trafford AW, Clarke JD, Richards MA, Eisner DA, Dibb KM. Calcium signalling microdomains and the t-tubular system in atrial mycoytes: potential roles in cardiac disease and arrhythmias. Cardiovasc Res 2013; 98:192-203. [PMID: 23386275 DOI: 10.1093/cvr/cvt018] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The atria contribute 25% to ventricular stroke volume and are the site of the commonest cardiac arrhythmia, atrial fibrillation (AF). The initiation of contraction in the atria is similar to that in the ventricle involving a systolic rise of intracellular Ca(2+) concentration ([Ca(2+)](i)). There are, however, substantial inter-species differences in the way systolic Ca(2+) is regulated in atrial cells. These differences are a consequence of a well-developed and functionally relevant transverse (t)-tubule network in the atria of large mammals, including humans, and its virtual absence in smaller laboratory species such as the rat. Where T-tubules are absent, the systolic Ca(2+) transient results from a 'fire-diffuse-fire' sequential recruitment of Ca(2+) release sites from the cell edge to the centre and hence marked spatiotemporal heterogeneity of systolic Ca(2+). Conversely, the well-developed T-tubule network in large mammals ensures a near synchronous rise of [Ca(2+)](i). In addition to synchronizing the systolic rise of [Ca(2+)](i), the presence of T-tubules in the atria of large mammals, by virtue of localization of the L-type Ca(2+) channels and Na(+)-Ca(2+) exchanger antiporters on the T-tubules, may serve to, respectively, accelerate changes in the amplitude of the systolic Ca(2+) transient during inotropic manoeuvres and lower diastolic [Ca(2+)](i). On the other hand, the presence of T-tubules and hence wider cellular distribution of the Na(+)-Ca(2+) exchanger may predispose the atria of large mammals to Ca(2+)-dependent delayed afterdepolarizations (DADs); this may be a determining factor in why the atria of large mammals spontaneously develop and maintain AF.
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Affiliation(s)
- Andrew W Trafford
- Unit of Cardiac Physiology, Manchester Academic Health Science Centre, Institute of Cardiovascular Science, University of Manchester, 3.23 Core Technology Facility, 46 Grafton Street, Manchester M13 9PT, UK
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Sex differences in mechanisms of cardiac excitation-contraction coupling. Pflugers Arch 2013; 465:747-63. [PMID: 23417603 PMCID: PMC3651827 DOI: 10.1007/s00424-013-1233-0] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 01/29/2013] [Accepted: 01/30/2013] [Indexed: 11/25/2022]
Abstract
The incidence and expression of cardiovascular diseases differs between the sexes. This is not surprising, as cardiac physiology differs between men and women. Clinical and basic science investigations have shown important sex differences in cardiac structure and function. The pervasiveness of sex differences suggests that such differences must be fundamental, likely operating at a cellular level. Indeed, studies have shown that isolated ventricular myocytes from female animals have smaller and slower contractions and underlying calcium transients compared to males. Recent evidence suggests that this arises from sex differences in components of the cardiac excitation–contraction coupling pathway, the sequence of events linking myocyte depolarization to calcium release from the sarcoplasmic reticulum and subsequent contraction. The concept that sex hormones may regulate intracellular calcium at the level of the cardiomyocyte is important, as levels of these hormones decline in both men and women as the incidence of cardiovascular disease rises. This review focuses on the impact of sex on cardiac contraction, in particular at the cellular level, and highlights specific components of the excitation–contraction coupling pathway that differ between the sexes. Understanding sex hormone regulation of calcium homeostasis in the heart may reveal new avenues for therapeutic strategies to treat cardiac dysfunction and cardiovascular diseases.
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Jayasinghe I, Crossman D, Soeller C, Cannell M. Comparison of the organization of T-tubules, sarcoplasmic reticulum and ryanodine receptors in rat and human ventricular myocardium. Clin Exp Pharmacol Physiol 2013; 39:469-76. [PMID: 21790719 DOI: 10.1111/j.1440-1681.2011.05578.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. It is apparent from the literature that there are significant differences in excitation-contraction coupling between species, particularly in the density of calcium transporting proteins in the t-system and sarcoplasmic reticulum (SR) Ca(2+) release channels. Unfortunately, there is a lack of information as to how the principal structures that link electrical excitation to the activation of calcium-induced calcium release (CICR) are different between human and animal models (particularly rat). 2. Comparison of wheat germ agglutinin and caveolin-3 labelling revealed a non-uniform distribution of surface membrane glycosylation in the rat, rabbit and human, and that the rat t-system appeared more complex in geometry than the latter species. Analysis of the t-system skeleton showed that the t-system was highly branched in the rat compared with that of the human (0.8 ± 0.08 and 0.2 ± 0.07 branch points per μm(2) , respectively; P < 0.001). 3. We also compared the distribution of contractile machinery, sodium-calcium exchange, SR and ryanodine receptors (RyR) in rat and human. F-Actin and RyR labelling was used to estimate the area of contractile apparatus supplied by each RyR cluster. In the rat, each RyR cluster supplied an average cross-sectional area of contractile machinery of 0.36 ± 0.03μm(2) compared with 0.49 ± 0.04 μm(2) in human (P = 0.048). Sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA2a) labelling showed that the SR formed a tight network of loops surrounding contractile fibrils that were denser than the t-tubule network, but otherwise appeared similar in both species. 4. In general, the results show a higher density in structures involved in CICR in the rat compared with human.
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Affiliation(s)
- Id Jayasinghe
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
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Calcium flux balance in the heart. J Mol Cell Cardiol 2012; 58:110-7. [PMID: 23220128 DOI: 10.1016/j.yjmcc.2012.11.017] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 11/08/2012] [Accepted: 11/22/2012] [Indexed: 11/22/2022]
Abstract
This article reviews the consequences of the need for the cardiac cell to be in calcium flux balance in the steady state. We first discuss how this steady state condition affects the control of resting [Ca(2+)]i. The next section considers how sarcoplasmic reticulum (SR) Ca content is controlled by a feedback mechanism whereby changes of SR Ca affect the amplitude of the Ca transient and this, in turn, controls sarcolemmal Ca fluxes. Subsequent sections review the effects of altering the activity of individual Ca handling proteins. Increasing the activity of the SR Ca-ATPase (SERCA) increases both the amplitude and rate constant of decay of the systolic Ca transient. The Ca flux balance condition requires that this must be achieved with no change of Ca efflux placing constraints on the magnitude of change of amplitude and decay rate. We analyze the quantitative dependence of Ca transient amplitude and SR content on SERCA activity. Increasing the open probability of the RyR during systole is predicted to have no steady state effect on the amplitude of the systolic Ca transient. We discuss the effects of changing the amplitude of the L-type Ca current in the context of both triggering Ca release from the SR and loading the cell with calcium. These manoeuvres are considered in the context of the effects of β-adrenergic stimulation. Finally, we review calcium flux balance in the presence of Ca waves.
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Niggli E, Ullrich ND, Gutierrez D, Kyrychenko S, Poláková E, Shirokova N. Posttranslational modifications of cardiac ryanodine receptors: Ca(2+) signaling and EC-coupling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:866-75. [PMID: 22960642 DOI: 10.1016/j.bbamcr.2012.08.016] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 08/18/2012] [Accepted: 08/22/2012] [Indexed: 10/27/2022]
Abstract
In cardiac muscle, a number of posttranslational protein modifications can alter the function of the Ca(2+) release channel of the sarcoplasmic reticulum (SR), also known as the ryanodine receptor (RyR). During every heartbeat RyRs are activated by the Ca(2+)-induced Ca(2+) release mechanism and contribute a large fraction of the Ca(2+) required for contraction. Some of the posttranslational modifications of the RyR are known to affect its gating and Ca(2+) sensitivity. Presently, research in a number of laboratories is focused on RyR phosphorylation, both by PKA and CaMKII, or on RyR modifications caused by reactive oxygen and nitrogen species (ROS/RNS). Both classes of posttranslational modifications are thought to play important roles in the physiological regulation of channel activity, but are also known to provoke abnormal alterations during various diseases. Only recently it was realized that several types of posttranslational modifications are tightly connected and form synergistic (or antagonistic) feed-back loops resulting in additive and potentially detrimental downstream effects. This review summarizes recent findings on such posttranslational modifications, attempts to bridge molecular with cellular findings, and opens a perspective for future work trying to understand the ramifications of crosstalk in these multiple signaling pathways. Clarifying these complex interactions will be important in the development of novel therapeutic approaches, since this may form the foundation for the implementation of multi-pronged treatment regimes in the future. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Cardiac Pathways of Differentiation, Metabolism and Contraction.
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Affiliation(s)
- Ernst Niggli
- Department of Physiology, University of Bern, Bern, Switzerland.
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Sulemanji DS, Bloom JD, Dzik WH, Jiang Y. New insights into the effect of rapid transfusion of fresh frozen plasma on ionized calcium. J Clin Anesth 2012; 24:364-9. [DOI: 10.1016/j.jclinane.2011.10.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 09/15/2011] [Accepted: 10/01/2011] [Indexed: 10/28/2022]
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Role of t-tubules in the control of trans-sarcolemmal ion flux and intracellular Ca2+ in a model of the rat cardiac ventricular myocyte. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 41:491-503. [PMID: 22466899 DOI: 10.1007/s00249-012-0804-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 03/09/2012] [Accepted: 03/13/2012] [Indexed: 10/28/2022]
Abstract
The t-tubules of mammalian ventricular myocytes are invaginations of the surface membrane that form a complex network within the cell, with restricted diffusion to the bulk extracellular space. The trans-sarcolemmal flux of many ions, including Ca(2+), occurs predominantly across the t-tubule membrane and thus into and out of this restricted diffusion space. It seems possible, therefore, that ion concentration changes may occur in the t-tubule lumen, which would alter ion flux across the t-tubule membrane. We have used a computer model of the ventricular myocyte, incorporating a t-tubule compartment and experimentally determined values for diffusion between the t-tubule lumen and bulk extracellular space, and ion fluxes across the t-tubule membrane, to investigate this possibility. The results show that influx and efflux of different ion species across the t-tubule membrane are similar, but not equal. Changes of ion concentration can therefore occur close to the t-tubular membrane, thereby altering trans-sarcolemmal ion flux and thus cell function, although such changes are reduced by diffusion to the bulk extracellular space. Slowing diffusion results in larger changes in luminal ion concentrations. These results provide a deeper understanding of the role of the t-tubules in normal cell function, and are a basis for understanding the changes that occur in heart failure as a result of changes in t-tubule structure and ion fluxes.
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Fernández-Velasco M, Ruiz-Hurtado G, Rueda A, Neco P, Mercado-Morales M, Delgado C, Napolitano C, Priori SG, Richard S, María Gómez A, Benitah JP. RyRCa2+ leak limits cardiac Ca2+ window current overcoming the tonic effect of calmodulinin mice. PLoS One 2011; 6:e20863. [PMID: 21673970 PMCID: PMC3108979 DOI: 10.1371/journal.pone.0020863] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 05/13/2011] [Indexed: 11/19/2022] Open
Abstract
Ca2+ mediates the functional coupling between L-type Ca2+ channel (LTCC) and sarcoplasmic reticulum (SR) Ca2+ release channel (ryanodine receptor, RyR), participating in key pathophysiological processes. This crosstalk manifests as the orthograde Ca2+-induced Ca2+-release (CICR) mechanism triggered by Ca2+ influx, but also as the retrograde Ca2+-dependent inactivation (CDI) of LTCC, which depends on both Ca2+ permeating through the LTCC itself and on SR Ca2+ release through the RyR. This latter effect has been suggested to rely on local rather than global Ca2+ signaling, which might parallel the nanodomain control of CDI carried out through calmodulin (CaM). Analyzing the CICR in catecholaminergic polymorphic ventricular tachycardia (CPVT) mice as a model of RyR-generated Ca2+ leak, we evidence here that increased occurrence of the discrete local SR Ca2+ releases through the RyRs (Ca2+ sparks) causea depolarizing shift in activation and a hyperpolarizing shift inisochronic inactivation of cardiac LTCC current resulting in the reduction of window current. Both increasing fast [Ca2+]i buffer capacity or depleting SR Ca2+ store blunted these changes, which could be reproduced in WT cells by RyRCa2+ leak induced with Ryanodol and CaM inhibition.Our results unveiled a new paradigm for CaM-dependent effect on LTCC gating and further the nanodomain Ca2+ control of LTCC, emphasizing the importance of spatio-temporal relationships between Ca2+ signals and CaM function.
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Affiliation(s)
- María Fernández-Velasco
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, Madrid, Spain
| | - Gema Ruiz-Hurtado
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Inserm, U769, IFR141, Faculté de Pharmacie, Université Paris-Sud 11, Chatenay-Malabry, France
| | - Angélica Rueda
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Department of Biochemistry, CINVESTAV, Mexico City, Mexico
| | - Patricia Neco
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Inserm, U769, IFR141, Faculté de Pharmacie, Université Paris-Sud 11, Chatenay-Malabry, France
| | | | - Carmen Delgado
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, CyB, CSIC, Madrid, Spain
| | - Carlo Napolitano
- Molecular Cardiology, Fondazione Salvatore Maugeri, Pavia, Italy
- Cardiovascular Genetics, Leon Charney Division of Cardiology, Langone Medical Center, New York University School of Medicine, New York, United States of America
| | - Silvia G. Priori
- Molecular Cardiology, Fondazione Salvatore Maugeri, Pavia, Italy
- Cardiovascular Genetics, Leon Charney Division of Cardiology, Langone Medical Center, New York University School of Medicine, New York, United States of America
- Department of Cardiology, University of Pavia, Italy
| | - Sylvain Richard
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Inserm, U1046, Université Montpellier-1, Université Montpellier-2, Montpellier, France
| | - Ana María Gómez
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Inserm, U769, IFR141, Faculté de Pharmacie, Université Paris-Sud 11, Chatenay-Malabry, France
| | - Jean-Pierre Benitah
- Inserm, U637, Université Montpellier-1, Université Montpellier-2, Montpellier, France
- Inserm, U769, IFR141, Faculté de Pharmacie, Université Paris-Sud 11, Chatenay-Malabry, France
- * E-mail:
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Cannell MB, Kong CHT. Local control in cardiac E-C coupling. J Mol Cell Cardiol 2011; 52:298-303. [PMID: 21586292 DOI: 10.1016/j.yjmcc.2011.04.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 04/12/2011] [Accepted: 04/29/2011] [Indexed: 10/18/2022]
Abstract
The development of local control theories in cardiac excitation-contraction coupling solved a major problem in the calcium-induced calcium release (CICR) hypothesis. Local control explained how regeneration, inherent in the CICR mechanism, might be limited spatially to enable graded Ca release (and force production). The key lies in the stochastic recruitment of individual calcium release units (couplons or CRUs) where adjacent CRUs are partially uncoupled by the distance between them. In the CRU, individual groups of sarcoplasmic reticulum calcium release channels (RyRs) are very close to the surface membrane where calcium influx, controlled by membrane depolarization, leads to high local Ca levels that enable a high speed response from RyRs that have a very low probability to opening at resting Ca levels. However, calcium diffusion from an activated CRU results in adjacent CRUs being exposed to much lower levels of Ca and probability of activation. This effectively uncouples the CRUs and limits overall regenerative gain to enable stability without compromising sensitivity. Nevertheless, it is still unclear how the CRU terminates its release of calcium on the physiological timescale, and possible mechanisms (and problems) are briefly reviewed. We suggest that modulation in RyR gating may serve to control average SR Ca levels to regulate other metabolic functions of the sarco(endo)plasmic reticulum beyond regulating contractility. This article is part of a special issue entitled "Local Signaling in Myocytes."
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Affiliation(s)
- M B Cannell
- School of Physiology & Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK.
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