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Taha M, Assali EA, Ben-Kasus T, Stuzmann GE, Shirihai OS, Hershfinkel M, Sekler I. NCLX controls hepatic mitochondrial Ca 2+ extrusion and couples hormone-mediated mitochondrial Ca 2+ oscillations with gluconeogenesis. Mol Metab 2024:101982. [PMID: 38960129 DOI: 10.1016/j.molmet.2024.101982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/26/2024] [Accepted: 06/27/2024] [Indexed: 07/05/2024] Open
Abstract
OBJECTIVE Hepatic Ca2+ signaling has been identified as a crucial key factor in driving gluconeogenesis. The involvement of mitochondria in hormone-induced Ca2+ signaling and their contribution to metabolic activity remain, however, poorly understood. Moreover, the molecular mechanism governing the mitochondrial Ca2+ efflux signaling remains unresolved. This study investigates the role of the Na+/Ca2+ exchanger, NCLX, in modulating hepatic mitochondrial Ca2+ efflux, and examines its physiological significance in hormonal hepatic Ca2+ signaling, gluconeogenesis, and mitochondrial bioenergetics. METHODS Primary mouse hepatocytes from both an AAV-mediated conditional hepatic-specific and a total mitochondrial Na+/Ca2+ exchanger, NCLX, knock-out (KO) mouse models were employed for fluorescent monitoring of purinergic and glucagon/vasopressin-dependent mitochondrial and cytosolic hepatic Ca2+ responses in cultured hepatocytes. Isolated liver mitochondria and permeabilized primary hepatocytes were utilized to analyze the ion-dependence of Ca2+ efflux. Utilizing the conditional hepatic-specific NCLX KO model, the rate of gluconeogenesis was assessed first through the monitoring of glucose levels in fasted mice in vivo and by subjecting the fasted mice to a pyruvate tolerance test while monitoring blood glucose. Additionally, cultured primary hepatocytes from both genotypes were assessed in vitro for glucagon-dependent glucose production and cellular bioenergetics through glucose oxidase assay and Seahorse respirometry, respectively. RESULTS Analysis of Ca2+ responses in isolated liver mitochondria and cultured primary hepatocytes from NCLX KO versus WT mice showed that NCLX serves as the principal mechanism for mitochondrial calcium extrusion in hepatocytes. We then determined the role of NCLX in glucagon and vasopressin-induced Ca2+ oscillations. Consistent with previous studies, glucagon and vasopressin triggered Ca2+ oscillations in WT hepatocytes, however, the deletion of NCLX resulted in selective elimination of mitochondrial, but not cytosolic, Ca2+ oscillations or level of IP3R1 expression, underscoring NCLX's pivotal role in mitochondrial Ca2+ regulation. Subsequent in vivo investigation for hepatic NCLX role in gluconeogenesis revealed that, as opposed to WT mice which maintained normoglycemic blood glucose levels when fasted, conditional hepatic-specific NCLX KO mice exhibited a faster drop in glucose levels, becoming hypoglycemic, and with a compromised conversion of pyruvate to glucose when provided challenged under fasting conditions. Concurrent in vitro assessments showed impaired glucagon-dependent glucose production and compromised bioenergetics in KO hepatocytes, thereby underscoring NCLX's significant contribution to hepatic glucose metabolism. CONCLUSIONS The study findings demonstrate that NCLX acts as the primary Ca2+ efflux mechanism in hepatocytes. NCLX is indispensable for the regulation of hormone-induced mitochondrial Ca2+ oscillations, mitochondrial metabolism and sustenance of hepatic gluconeogenesis.
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Affiliation(s)
- Mahmoud Taha
- Department of Physiology and Cell Biology, Ben Gurion University, Beer-Sheva 8410501, Israel
| | - Essam A Assali
- Department of Physiology and Cell Biology, Ben Gurion University, Beer-Sheva 8410501, Israel; Department of Medicine, Endocrinology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095 USA; Metabolism Theme, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - Tsipi Ben-Kasus
- Department of Physiology and Cell Biology, Ben Gurion University, Beer-Sheva 8410501, Israel
| | - Grace E Stuzmann
- Center for Neurodegenerative Disease and Therapeutics, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA
| | - Orian S Shirihai
- Department of Medicine, Endocrinology, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095 USA; Metabolism Theme, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA; Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Michal Hershfinkel
- Department of Physiology and Cell Biology, Ben Gurion University, Beer-Sheva 8410501, Israel
| | - Israel Sekler
- Department of Physiology and Cell Biology, Ben Gurion University, Beer-Sheva 8410501, Israel.
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Hassan N, Murray BG, Jagadeeshan S, Thomas R, Katselis GS, Ianowski JP. Intracellular Ca 2+ oscillation frequency and amplitude modulation mediate epithelial apical and basolateral membranes crosstalk. iScience 2024; 27:108629. [PMID: 38188522 PMCID: PMC10767210 DOI: 10.1016/j.isci.2023.108629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 10/04/2023] [Accepted: 11/30/2023] [Indexed: 01/09/2024] Open
Abstract
Since the early seminal studies on epithelial solute transport, it has been understood that there must be crosstalk among different members of the transport machinery to coordinate their activity and, thus, generate localized electrochemical gradients that force solute flow in the required direction that would otherwise be thermodynamically unfavorable. However, mechanisms underlying intracellular crosstalk remain unclear. We present evidence that crosstalk between apical and basolateral membrane transporters is mediated by intracellular Ca2+ signaling in insect renal epithelia. Ion flux across the basolateral membrane is encoded in the intracellular Ca2+ oscillation frequency and amplitude modulation and that information is used by the apical membrane to adjust ion flux accordingly. Moreover, imposing experimentally generated intracellular Ca2+ oscillation modulation causes cells to predictably adjust their ion transport properties. Our results suggest that intracellular Ca2+ oscillation frequency and amplitude modulation encode information on transmembrane ion flux that is required for crosstalk.
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Affiliation(s)
- Noman Hassan
- Department of Anatomy Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon S7N 5E5, Canada
| | - Brendan G. Murray
- Department of Anatomy Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon S7N 5E5, Canada
| | | | - Robert Thomas
- Department of Anatomy Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon S7N 5E5, Canada
| | - George S. Katselis
- Department of Medicine, Division of Canadian Centre for Rural and Agricultural Health, College of Medicine, University of Saskatchewan, Saskatoon S7N 2Z4, Canada
| | - Juan P. Ianowski
- Department of Anatomy Physiology and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon S7N 5E5, Canada
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Paknejad N, Sapuru V, Hite RK. Structural titration reveals Ca 2+-dependent conformational landscape of the IP 3 receptor. Nat Commun 2023; 14:6897. [PMID: 37898605 PMCID: PMC10613215 DOI: 10.1038/s41467-023-42707-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 10/18/2023] [Indexed: 10/30/2023] Open
Abstract
Inositol 1,4,5-trisphosphate receptors (IP3Rs) are endoplasmic reticulum Ca2+ channels whose biphasic dependence on cytosolic Ca2+ gives rise to Ca2+ oscillations that regulate fertilization, cell division and cell death. Despite the critical roles of IP3R-mediated Ca2+ responses, the structural underpinnings of the biphasic Ca2+ dependence that underlies Ca2+ oscillations are incompletely understood. Here, we collect cryo-EM images of an IP3R with Ca2+ concentrations spanning five orders of magnitude. Unbiased image analysis reveals that Ca2+ binding does not explicitly induce conformational changes but rather biases a complex conformational landscape consisting of resting, preactivated, activated, and inhibited states. Using particle counts as a proxy for relative conformational free energy, we demonstrate that Ca2+ binding at a high-affinity site allows IP3Rs to activate by escaping a low-energy resting state through an ensemble of preactivated states. At high Ca2+ concentrations, IP3Rs preferentially enter an inhibited state stabilized by a second, low-affinity Ca2+ binding site. Together, these studies provide a mechanistic basis for the biphasic Ca2+-dependence of IP3R channel activity.
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Affiliation(s)
- Navid Paknejad
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
- Physiology, Biophysics, and Systems Biology (PBSB) Program, Weill Cornell Graduate School of Biomedical Sciences, 1300 York Avenue, New York, NY, 10065, USA
| | - Vinay Sapuru
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
- Physiology, Biophysics, and Systems Biology (PBSB) Program, Weill Cornell Graduate School of Biomedical Sciences, 1300 York Avenue, New York, NY, 10065, USA
| | - Richard K Hite
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA.
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4
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Marolt U, Paradiž Leitgeb E, Pohorec V, Lipovšek S, Venglovecz V, Gál E, Ébert A, Menyhárt I, Potrč S, Gosak M, Dolenšek J, Stožer A. Calcium imaging in intact mouse acinar cells in acute pancreas tissue slices. PLoS One 2022; 17:e0268644. [PMID: 35657915 PMCID: PMC9165796 DOI: 10.1371/journal.pone.0268644] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/04/2022] [Indexed: 12/22/2022] Open
Abstract
The physiology and pathophysiology of the exocrine pancreas are in close connection to changes in intra-cellular Ca2+ concentration. Most of our knowledge is based on in vitro experiments on acinar cells or acini enzymatically isolated from their surroundings, which can alter their structure, physiology, and limit our understanding. Due to these limitations, the acute pancreas tissue slice technique was introduced almost two decades ago as a complementary approach to assess the morphology and physiology of both the endocrine and exocrine pancreas in a more conserved in situ setting. In this study, we extend previous work to functional multicellular calcium imaging on acinar cells in tissue slices. The viability and morphological characteristics of acinar cells within the tissue slice were assessed using the LIVE/DEAD assay, transmission electron microscopy, and immunofluorescence imaging. The main aim of our study was to characterize the responses of acinar cells to stimulation with acetylcholine and compare them with responses to cerulein in pancreatic tissue slices, with special emphasis on inter-cellular and inter-acinar heterogeneity and coupling. To this end, calcium imaging was performed employing confocal microscopy during stimulation with a wide range of acetylcholine concentrations and selected concentrations of cerulein. We show that various calcium oscillation parameters depend monotonically on the stimulus concentration and that the activity is rather well synchronized within acini, but not between acini. The acute pancreas tissue slice represents a viable and reliable experimental approach for the evaluation of both intra- and inter-cellular signaling characteristics of acinar cell calcium dynamics. It can be utilized to assess many cells simultaneously with a high spatiotemporal resolution, thus providing an efficient and high-yield platform for future studies of normal acinar cell biology, pathophysiology, and screening pharmacological substances.
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Affiliation(s)
- Urška Marolt
- Clinical department for abdominal and general surgery, University Medical Centre Maribor, Maribor, Slovenia
- * E-mail: (UM); (JD); (AS)
| | - Eva Paradiž Leitgeb
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Saška Lipovšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- Faculty of Chemistry and Chemical Engineering, University of Maribor, Maribor, Slovenia
| | - Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Eleonóra Gál
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Attila Ébert
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - István Menyhárt
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Stojan Potrč
- Clinical department for abdominal and general surgery, University Medical Centre Maribor, Maribor, Slovenia
| | - Marko Gosak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, Slovenia
- * E-mail: (UM); (JD); (AS)
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- * E-mail: (UM); (JD); (AS)
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5
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Receptor-specific Ca 2+ oscillation patterns mediated by differential regulation of P2Y purinergic receptors in rat hepatocytes. iScience 2021; 24:103139. [PMID: 34646983 PMCID: PMC8496176 DOI: 10.1016/j.isci.2021.103139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 07/26/2021] [Accepted: 09/14/2021] [Indexed: 11/21/2022] Open
Abstract
Extracellular agonists linked to inositol-1,4,5-trisphosphate (IP3) formation elicit cytosolic Ca2+ oscillations in many cell types, but despite a common signaling pathway, distinct agonist-specific Ca2+ spike patterns are observed. Using qPCR, we show that rat hepatocytes express multiple purinergic P2Y and P2X receptors (R). ADP acting through P2Y1R elicits narrow Ca2+ oscillations, whereas UTP acting through P2Y2R elicits broad Ca2+ oscillations, with composite patterns observed for ATP. P2XRs do not play a role at physiological agonist levels. The discrete Ca2+ signatures reflect differential effects of protein kinase C (PKC), which selectively modifies the falling phase of the Ca2+ spikes. Negative feedback by PKC limits the duration of P2Y1R-induced Ca2+ spikes in a manner that requires extracellular Ca2+. By contrast, P2Y2R is resistant to PKC negative feedback. Thus, the PKC leg of the bifurcated IP3 signaling pathway shapes unique Ca2+ oscillation patterns that allows for distinct cellular responses to different agonists. Distinct stereotypic Ca2+ oscillations are elicited by P2Y1 and P2Y2 receptors P2X receptors do not contribute to the generation of Ca2+ oscillations Agonist-specific Ca2+ spike shapes reflect discrete modes of PKC negative feedback Bifurcation of IP3/PKC signaling yields unique Ca2+ oscillation signatures
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Cloete I, Corrêa-Velloso JC, Bartlett PJ, Kirk V, Thomas AP, Sneyd J. A Tale of two receptors. J Theor Biol 2021; 518:110629. [PMID: 33607144 DOI: 10.1016/j.jtbi.2021.110629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 01/10/2021] [Accepted: 02/05/2021] [Indexed: 11/26/2022]
Abstract
Calcium (Ca2+) oscillations in hepatocytes have a wide dynamic range. In particular, recent experimental evidence shows that agonist stimulation of the P2Y family of receptors leads to qualitatively diverse Ca2+ oscillations. We present a new model of Ca2+ oscillations in hepatocytes based on these experiments to investigate the mechanisms controlling P2Y-activated Ca2+ oscillations. The model accounts for Ca2+ regulation of the IP3 receptor (IP3R), the positive feedback from Ca2+ on phospholipase C (PLC) and the P2Y receptor phosphorylation by protein kinase C (PKC). Furthermore, PKC is shown to control multiple cellular substrates. Utilising the model, we suggest the activity and intensity of PLC and PKC necessary to explain the qualitatively diverse Ca2+ oscillations in response to P2Y receptor activation.
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Affiliation(s)
- Ielyaas Cloete
- Department of Mathematics, University of Auckland, Auckland 1142, New Zealand
| | - Juliana C Corrêa-Velloso
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ 07103, United States
| | - Paula J Bartlett
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ 07103, United States
| | - Vivien Kirk
- Department of Mathematics, University of Auckland, Auckland 1142, New Zealand
| | - Andrew P Thomas
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ 07103, United States
| | - James Sneyd
- Department of Mathematics, University of Auckland, Auckland 1142, New Zealand
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7
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Gaspers LD, Thomas AP, Hoek JB, Bartlett PJ. Ethanol Disrupts Hormone-Induced Calcium Signaling in Liver. FUNCTION (OXFORD, ENGLAND) 2021; 2:zqab002. [PMID: 33604575 PMCID: PMC7875097 DOI: 10.1093/function/zqab002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/22/2020] [Accepted: 12/30/2020] [Indexed: 01/06/2023]
Abstract
Receptor-coupled phospholipase C (PLC) is an important target for the actions of ethanol. In the ex vivo perfused rat liver, concentrations of ethanol >100 mM were required to induce a rise in cytosolic calcium (Ca2+) suggesting that these responses may only occur after binge ethanol consumption. Conversely, pharmacologically achievable concentrations of ethanol (≤30 mM) decreased the frequency and magnitude of hormone-stimulated cytosolic and nuclear Ca2+ oscillations and the parallel translocation of protein kinase C-β to the membrane. Ethanol also inhibited gap junction communication resulting in the loss of coordinated and spatially organized intercellular Ca2+ waves in hepatic lobules. Increasing the hormone concentration overcame the effects of ethanol on the frequency of Ca2+ oscillations and amplitude of the individual Ca2+ transients; however, the Ca2+ responses in the intact liver remained disorganized at the intercellular level, suggesting that gap junctions were still inhibited. Pretreating hepatocytes with an alcohol dehydrogenase inhibitor suppressed the effects of ethanol on hormone-induced Ca2+ increases, whereas inhibiting aldehyde dehydrogenase potentiated the inhibitory actions of ethanol, suggesting that acetaldehyde is the underlying mediator. Acute ethanol intoxication inhibited the rate of rise and the magnitude of hormone-stimulated production of inositol 1,4,5-trisphosphate (IP3), but had no effect on the size of Ca2+ spikes induced by photolysis of caged IP3. These findings suggest that ethanol inhibits PLC activity, but does not affect IP3 receptor function. We propose that by suppressing hormone-stimulated PLC activity, ethanol interferes with the dynamic modulation of [IP3] that is required to generate large, amplitude Ca2+ oscillations.
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Affiliation(s)
- Lawrence D Gaspers
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA,Address correspondence to L.D.G. (e-mail: )
| | - Andrew P Thomas
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Jan B Hoek
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Paula J Bartlett
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
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8
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Kaimachnikov NP, Kotova PD, Kochkina EN, Rogachevskaja OA, Khokhlov AA, Bystrova MF, Kolesnikov SS. Modeling of Ca2+ transients initiated by GPCR agonists in mesenchymal stromal cells. BBA ADVANCES 2021; 1:100012. [PMID: 37082025 PMCID: PMC10074909 DOI: 10.1016/j.bbadva.2021.100012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 04/05/2021] [Accepted: 04/11/2021] [Indexed: 10/21/2022] Open
Abstract
The integrative study that included experimentation and mathematical modeling was carried out to analyze dynamic aspects of transient Ca2+ signaling induced by brief pulses of GPCR agonists in mesenchymal stromal cells from the human adipose tissue (AD-MSCs). The experimental findings argued for IP3/Ca2+-regulated Ca2+ release via IP3 receptors (IP3Rs) as a key mechanism mediating agonist-dependent Ca2+ transients. The consistent signaling circuit was proposed to formalize coupling of agonist binding to Ca2+ mobilization for mathematical modeling. The model properly simulated the basic phenomenology of agonist transduction in AD-MSCs, which mostly produced single Ca2+ spikes upon brief stimulation. The spike-like responses were almost invariantly shaped at different agonist doses above a threshold, while response lag markedly decreased with stimulus strength. In AD-MSCs, agonists and IP3 uncaging elicited similar Ca2+ transients but IP3 pulses released Ca2+ without pronounced delay. This suggested that IP3 production was rate-limiting in agonist transduction. In a subpopulation of AD-MSCs, brief agonist pulses elicited Ca2+ bursts crowned by damped oscillations. With properly adjusted parameters of IP3R inhibition by cytosolic Ca2+, the model reproduced such oscillatory Ca2+ responses as well. GEM-GECO1 and R-CEPIA1er, the genetically encoded sensors of cytosolic and reticular Ca2+, respectively, were co-expressed in HEK-293 cells that also responded to agonists in an "all-or-nothing" manner. The experimentally observed Ca2+ signals triggered by ACh in both compartments were properly simulated with the suggested signaling circuit. Thus, the performed modeling of the transduction process provides sufficient theoretical basis for deeper interpretation of experimental findings on agonist-induced Ca2+ signaling in AD-MSCs.
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9
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Dual mechanisms of Ca2+ oscillations in hepatocytes. J Theor Biol 2020; 503:110390. [DOI: 10.1016/j.jtbi.2020.110390] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/19/2020] [Accepted: 06/24/2020] [Indexed: 11/30/2022]
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10
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Bartlett PJ, Cloete I, Sneyd J, Thomas AP. IP 3-Dependent Ca 2+ Oscillations Switch into a Dual Oscillator Mechanism in the Presence of PLC-Linked Hormones. iScience 2020; 23:101062. [PMID: 32353764 PMCID: PMC7191650 DOI: 10.1016/j.isci.2020.101062] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 12/11/2019] [Accepted: 04/09/2020] [Indexed: 11/28/2022] Open
Abstract
Ca2+ oscillations that depend on inositol-1,4,5-trisphosphate (IP3) have been ascribed to biphasic Ca2+ regulation of the IP3 receptor (IP3R) or feedback mechanisms controlling IP3 levels in different cell types. IP3 uncaging in hepatocytes elicits Ca2+ transients that are often localized at the subcellular level and increase in magnitude with stimulus strength. However, this does not reproduce the broad baseline-separated global Ca2+ oscillations elicited by vasopressin. Addition of hormone to cells activated by IP3 uncaging initiates a qualitative transition from high-frequency spatially disorganized Ca2+ transients, to low-frequency, oscillatory Ca2+ waves that propagate throughout the cell. A mathematical model with dual coupled oscillators that integrates Ca2+-induced Ca2+ release at the IP3R and mutual feedback mechanisms of cross-coupling between Ca2+ and IP3 reproduces this behavior. Thus, multiple Ca2+ oscillation modes can coexist in the same cell, and hormonal stimulation can switch from the simpler to the more complex to yield robust signaling.
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Affiliation(s)
- Paula J Bartlett
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Ielyaas Cloete
- Department of Mathematics, The University of Auckland, Auckland, New Zealand
| | - James Sneyd
- Department of Mathematics, The University of Auckland, Auckland, New Zealand
| | - Andrew P Thomas
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ 07103, USA.
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11
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Roach KM, Bradding P. Ca 2+ signalling in fibroblasts and the therapeutic potential of K Ca3.1 channel blockers in fibrotic diseases. Br J Pharmacol 2020; 177:1003-1024. [PMID: 31758702 DOI: 10.1111/bph.14939] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 10/23/2019] [Accepted: 11/13/2019] [Indexed: 12/13/2022] Open
Abstract
The role of Ca2+ signalling in fibroblasts is of great interest in fibrosis-related diseases. Intracellular free Ca2+ ([Ca2+ ]i ) is a ubiquitous secondary messenger, regulating a number of cellular functions such as secretion, metabolism, differentiation, proliferation and contraction. The intermediate conductance Ca2+ -activated K+ channel KCa 3.1 is pivotal in Ca2+ signalling and plays a central role in fibroblast processes including cell activation, migration and proliferation through the regulation of cell membrane potential. Evidence from a number of approaches demonstrates that KCa 3.1 plays an important role in the development of many fibrotic diseases, including idiopathic pulmonary, renal tubulointerstitial fibrosis and cardiovascular disease. The KCa 3.1 selective blocker senicapoc was well tolerated in clinical trials for sickle cell disease, raising the possibility of rapid translation to the clinic for people suffering from pathological fibrosis. This review after analysing all the data, concludes that targeting KCa 3.1 should be a high priority for human fibrotic disease.
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Affiliation(s)
- Katy M Roach
- Institute for Lung Health, Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - Peter Bradding
- Institute for Lung Health, Department of Respiratory Sciences, University of Leicester, Leicester, UK
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Abstract
Ionized calcium (Ca2+) is the most versatile cellular messenger. All cells use Ca2+ signals to regulate their activities in response to extrinsic and intrinsic stimuli. Alterations in cellular Ca2+ signaling and/or Ca2+ homeostasis can subvert physiological processes into driving pathological outcomes. Imaging of living cells over the past decades has demonstrated that Ca2+ signals encode information in their frequency, kinetics, amplitude, and spatial extent. These parameters alter depending on the type and intensity of stimulation, and cellular context. Moreover, it is evident that different cell types produce widely varying Ca2+ signals, with properties that suit their physiological functions. This primer discusses basic principles and mechanisms underlying cellular Ca2+ signaling and Ca2+ homeostasis. Consequently, we have cited some historical articles in addition to more recent findings. A brief summary of the core features of cellular Ca2+ signaling is provided, with particular focus on Ca2+ stores and Ca2+ transport across cellular membranes, as well as mechanisms by which Ca2+ signals activate downstream effector systems.
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13
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Gaspers LD, Pierobon N, Thomas AP. Intercellular calcium waves integrate hormonal control of glucose output in the intact liver. J Physiol 2019; 597:2867-2885. [PMID: 30968953 PMCID: PMC6647271 DOI: 10.1113/jp277650] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 04/08/2019] [Indexed: 11/21/2022] Open
Abstract
Key points Sympathetic outflow and circulating glucogenic hormones both regulate liver function by increasing cytosolic calcium, although how these calcium signals are integrated at the tissue level is currently unknown. We show that stimulation of hepatic nerve fibres or perfusing the liver with physiological concentrations of vasopressin only will evoke localized cytosolic calcium oscillations and modest increases in hepatic glucose production. The combination of these stimuli acted synergistically to convert localized and asynchronous calcium responses into co‐ordinated intercellular calcium waves that spread throughout the liver lobule and elicited a synergistic increase in hepatic glucose production. The results obtained in the present study demonstrate that subthreshold levels of one hormone can create an excitable medium across the liver lobule, which allows global propagation of calcium signals in response to local sympathetic innervation and integration of metabolic regulation by multiple hormones. This enables the liver lobules to respond as functional units to produce full‐strength metabolic output at physiological levels of hormone.
Abstract Glucogenic hormones, including catecholamines and vasopressin, induce frequency‐modulated cytosolic Ca2+ oscillations in hepatocytes, and these propagate as intercellular Ca2+ waves via gap junctions in the intact liver. We investigated the role of co‐ordinated Ca2+ waves as a mechanism for integrating multiple endocrine and neuroendocrine inputs to control hepatic glucose production in perfused rat liver. Sympathetic nerve stimulation elicited localized Ca2+ increases that were restricted to hepatocytes in the periportal zone. During perfusion with subthreshold vasopressin, sympathetic stimulation converted asynchronous Ca2+ signals in a limited number of hepatocytes into co‐ordinated intercellular Ca2+ waves that propagated across entire lobules. A similar synergism was observed between physiological concentrations of glucagon and vasopressin, where glucagon also facilitated the recruitment of hepatocytes into a Ca2+ wave. Hepatic glucose production was significantly higher with intralobular Ca2+ waves. We propose that inositol 1,4,5‐trisphosphate (IP3)‐dependent Ca2+ signalling gives rise to an excitable medium across the functional syncytium of the hepatic lobule, co‐ordinating and amplifying the metabolic responses to multiple hormonal inputs. Sympathetic outflow and circulating glucogenic hormones both regulate liver function by increasing cytosolic calcium, although how these calcium signals are integrated at the tissue level is currently unknown. We show that stimulation of hepatic nerve fibres or perfusing the liver with physiological concentrations of vasopressin only will evoke localized cytosolic calcium oscillations and modest increases in hepatic glucose production. The combination of these stimuli acted synergistically to convert localized and asynchronous calcium responses into co‐ordinated intercellular calcium waves that spread throughout the liver lobule and elicited a synergistic increase in hepatic glucose production. The results obtained in the present study demonstrate that subthreshold levels of one hormone can create an excitable medium across the liver lobule, which allows global propagation of calcium signals in response to local sympathetic innervation and integration of metabolic regulation by multiple hormones. This enables the liver lobules to respond as functional units to produce full‐strength metabolic output at physiological levels of hormone.
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Affiliation(s)
- Lawrence D Gaspers
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Nicola Pierobon
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Andrew P Thomas
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, USA
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14
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Franca A, Filho ACML, Guerra MT, Weerachayaphorn J, dos Santos ML, Njei B, Robert M, Lima CX, Vidigal PVT, Banales JM, Ananthanarayanam M, Leite MF, Nathanson MH. Effects of Endotoxin on Type 3 Inositol 1,4,5-Trisphosphate Receptor in Human Cholangiocytes. Hepatology 2019; 69:817-830. [PMID: 30141207 PMCID: PMC6351171 DOI: 10.1002/hep.30228] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 08/13/2018] [Indexed: 12/16/2022]
Abstract
Clinical conditions that result in endotoxemia, such as sepsis and alcoholic hepatitis (AH), often are accompanied by cholestasis. Although hepatocellular changes in response to lipopolysaccharide (LPS) have been well characterized, less is known about whether and how cholangiocytes contribute to this form of cholestasis. We examined effects of endotoxin on expression and function of the type 3 inositol trisphosphate receptor (ITPR3), because this is the main intracellular Ca2+ release channel in cholangiocytes, and loss of it impairs ductular bicarbonate secretion. Bile duct cells expressed the LPS receptor, Toll-like receptor 4 (TLR4), which links to activation of nuclear factor-κB (NF-κB). Analysis of the human ITPR3 promoter revealed five putative response elements to NF-κB, and promoter activity was inhibited by p65/p50. Nested 0.5- and 1.0-kilobase (kb) deletion fragments of the ITPR3 promoter were inhibited by NF-κB subunits. Chromatin immunoprecipitation (ChIP) assay showed that NF-κB interacts with the ITPR3 promoter, with an associated increase in H3K9 methylation. LPS decreased ITPR3 mRNA and protein expression and also decreased sensitivity of bile duct cells to calcium agonist stimuli. This reduction was reversed by inhibition of TLR4. ITPR3 expression was decreased or absent in cholangiocytes from patients with cholestasis of sepsis and from those with severe AH. Conclusion: Stimulation of TLR4 by LPS activates NF-κB to down-regulate ITPR3 expression in human cholangiocytes. This may contribute to the cholestasis that can be observed in conditions such as sepsis or AH.
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Affiliation(s)
- Andressa Franca
- Federal University of Minas Gerais (UFMG), Belo Horizonte, MG
| | | | - Mateus T. Guerra
- Section of Digestive Disease, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Jittima Weerachayaphorn
- Section of Digestive Disease, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | | | - Basile Njei
- Section of Digestive Disease, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Marie Robert
- Department of Pathology, Yale University School of Medicine, New Haven, CT
| | | | | | - Jesus M. Banales
- Department of Liver and Gastrointestinal Diseases, Biodonostia Research Institute, Donostia University Hospital, University of the Basque Country (UPV/EHU), San Sebastian, Spain
| | | | - M. Fatima Leite
- Federal University of Minas Gerais (UFMG), Belo Horizonte, MG
| | - Michael H. Nathanson
- Section of Digestive Disease, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
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15
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Goldbeter A. Dissipative structures in biological systems: bistability, oscillations, spatial patterns and waves. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2017.0376. [PMID: 29891498 PMCID: PMC6000149 DOI: 10.1098/rsta.2017.0376] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/26/2018] [Indexed: 05/05/2023]
Abstract
The goal of this review article is to assess how relevant is the concept of dissipative structure for understanding the dynamical bases of non-equilibrium self-organization in biological systems, and to see where it has been applied in the five decades since it was initially proposed by Ilya Prigogine. Dissipative structures can be classified into four types, which will be considered, in turn, and illustrated by biological examples: (i) multistability, in the form of bistability and tristability, which involve the coexistence of two or three stable steady states, or in the form of birhythmicity, which involves the coexistence between two stable rhythms; (ii) temporal dissipative structures in the form of sustained oscillations, illustrated by biological rhythms; (iii) spatial dissipative structures, known as Turing patterns; and (iv) spatio-temporal structures in the form of propagating waves. Rhythms occur with widely different periods at all levels of biological organization, from neural, cardiac and metabolic oscillations to circadian clocks and the cell cycle; they play key roles in physiology and in many disorders. New rhythms are being uncovered while artificial ones are produced by synthetic biology. Rhythms provide the richest source of examples of dissipative structures in biological systems. Bistability has been observed experimentally, but has primarily been investigated in theoretical models in an increasingly wide range of biological contexts, from the genetic to the cell and animal population levels, both in physiological conditions and in disease. Bistable transitions have been implicated in the progression between the different phases of the cell cycle and, more generally, in the process of cell fate specification in the developing embryo. Turing patterns are exemplified by the formation of some periodic structures in the course of development and by skin stripe patterns in animals. Spatio-temporal patterns in the form of propagating waves are observed within cells as well as in intercellular communication. This review illustrates how dissipative structures of all sorts abound in biological systems.This article is part of the theme issue 'Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 1)'.
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Affiliation(s)
- Albert Goldbeter
- Unité de Chronobiologie théorique, Service de Chimie physique et Biologie théorique, Faculté des Sciences, Université Libre de Bruxelles (ULB), Campus Plaine, CP 231, 1050 Brussels, Belgium
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16
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Falcke M, Moein M, Tilūnaitė A, Thul R, Skupin A. On the phase space structure of IP 3 induced Ca 2+ signalling and concepts for predictive modeling. CHAOS (WOODBURY, N.Y.) 2018; 28:045115. [PMID: 31906671 DOI: 10.1063/1.5021073] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The correspondence between mathematical structures and experimental systems is the basis of the generalizability of results found with specific systems and is the basis of the predictive power of theoretical physics. While physicists have confidence in this correspondence, it is less recognized in cellular biophysics. On the one hand, the complex organization of cellular dynamics involving a plethora of interacting molecules and the basic observation of cell variability seem to question its possibility. The practical difficulties of deriving the equations describing cellular behaviour from first principles support these doubts. On the other hand, ignoring such a correspondence would severely limit the possibility of predictive quantitative theory in biophysics. Additionally, the existence of functional modules (like pathways) across cell types suggests also the existence of mathematical structures with comparable universality. Only a few cellular systems have been sufficiently investigated in a variety of cell types to follow up these basic questions. IP3 induced Ca2+signalling is one of them, and the mathematical structure corresponding to it is subject of ongoing discussion. We review the system's general properties observed in a variety of cell types. They are captured by a reaction diffusion system. We discuss the phase space structure of its local dynamics. The spiking regime corresponds to noisy excitability. Models focussing on different aspects can be derived starting from this phase space structure. We discuss how the initial assumptions on the set of stochastic variables and phase space structure shape the predictions of parameter dependencies of the mathematical models resulting from the derivation.
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Affiliation(s)
- Martin Falcke
- Max Delbrück Centre for Molecular Medicine, Robert Rössler Strasse 10, 13125 Berlin, Germany and Department of Physics, Humboldt University, Newtonstr. 15, 12489 Berlin, Germany
| | - Mahsa Moein
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, 7, Rue de Swing, Belval L-4367, Luxembourg
| | - Agne Tilūnaitė
- Systems Biology Laboratory, School of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Rüdiger Thul
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Alexander Skupin
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, 7, Rue de Swing, Belval L-4367, Luxembourg
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17
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Li X, Zhang S, Liu X, Wang X, Zhou A, Liu P. Dynamic analysis on the calcium oscillation model considering the influences of mitochondria. Biosystems 2017; 163:36-46. [PMID: 29229425 DOI: 10.1016/j.biosystems.2017.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 10/08/2017] [Accepted: 12/05/2017] [Indexed: 11/26/2022]
Abstract
Based on the model considering the influences of mitochondria, a further theoretical study on the dynamic behaviors of calcium signals is made. First of all, the reason for the generation and disappearance of calcium oscillations is verified in theory. Second, an analysis on the model considering the influences of mitochondria and the model neglecting the influences of mitochondria is carried out. Third, β (representing calcium leak) is introduced and it can be found that with the increase of β, the Hopf bifurcation points of system move towards the decreasing direction of μ (representing stimulus intensity) and calcium oscillations region gradually decreases. Forth, the study on τh (representing relaxation time) indicates that with the increase of τh, the second Hopf bifurcation point of system moves towards the increasing direction of μ and calcium oscillations region gradually increases. Under certain stimulus intensity, when relaxation time increases, calcium oscillation peak rises rapidly and the period increases obviously. Fifth, two-parameter bifurcation diagram of Vm1 (representing mitochondria activity) and μ contains three regions: stable region, oscillation region and unstable region. When the parameters fall in the unstable region Ca2+ gather towards mitochondria and further lead to cell apoptosis. With the increase of Vm1, calcium oscillations region shrinks gradually. Vm1 and μ both play a key role in regulating cell apoptosis. Only when Vm1 and μ are high enough can cells enter into programmed cell death and the higher Vm1 is, the lower the stimulus intensity required by cell apoptosis is.
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Affiliation(s)
- Xiang Li
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, PR China; Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300354, PR China.
| | - Suxia Zhang
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, PR China; Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300354, PR China.
| | - Xijun Liu
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, PR China; Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300354, PR China
| | - Xiaojing Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300354, PR China
| | - Anqi Zhou
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, PR China; Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300354, PR China
| | - Peng Liu
- Department of Mechanics, School of Mechanical Engineering, Tianjin University, Tianjin 300354, PR China; Tianjin Key Laboratory of Nonlinear Dynamics and Chaos Control, Tianjin 300354, PR China
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18
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Abstract
Sustained oscillations abound in biological systems. They occur at all levels of biological organization over a wide range of periods, from a fraction of a second to years, and with a variety of underlying mechanisms. They control major physiological functions, and their dysfunction is associated with a variety of physiological disorders. The goal of this review is (i) to give an overview of the main rhythms observed at the cellular and supracellular levels, (ii) to briefly describe how the study of biological rhythms unfolded in the course of time, in parallel with studies on chemical oscillations, (iii) to present the major roles of biological rhythms in the control of physiological functions, and (iv) the pathologies associated with the alteration, disappearance, or spurious occurrence of biological rhythms. Two tables present the main examples of cellular and supracellular rhythms ordered according to their period, and their role in physiology and pathophysiology. Among the rhythms discussed are neural and cardiac rhythms, metabolic oscillations such as those occurring in glycolysis in yeast, intracellular Ca++ oscillations, cyclic AMP oscillations in Dictyostelium amoebae, the segmentation clock that controls somitogenesis, pulsatile hormone secretion, circadian rhythms which occur in all eukaryotes and some bacteria with a period close to 24 h, the oscillatory dynamics of the enzymatic network driving the cell cycle, and oscillations in transcription factors such as NF-ΚB and tumor suppressors such as p53. Ilya Prigogine's concept of dissipative structures applies to temporal oscillations and allows us to unify within a common framework the various rhythms observed at different levels of biological organization, regardless of their period and underlying mechanism.
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Affiliation(s)
- Albert Goldbeter
- Unité de Chronobiologie théorique, Service de Chimie physique et Biologie théorique, Faculté des Sciences, Université Libre de Bruxelles (ULB), Campus Plaine, CP 231, B-1050 Brussels, Belgium
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19
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Bartlett PJ, Antony AN, Agarwal A, Hilly M, Prince VL, Combettes L, Hoek JB, Gaspers LD. Chronic alcohol feeding potentiates hormone-induced calcium signalling in hepatocytes. J Physiol 2017; 595:3143-3164. [PMID: 28220501 DOI: 10.1113/jp273891] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 01/26/2017] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Chronic alcohol consumption causes a spectrum of liver diseases, but the pathogenic mechanisms driving the onset and progression of disease are not clearly defined. We show that chronic alcohol feeding sensitizes rat hepatocytes to Ca2+ -mobilizing hormones resulting in a leftward shift in the concentration-response relationship and the transition from oscillatory to more sustained and prolonged Ca2+ increases. Our data demonstrate that alcohol-dependent adaptation in the Ca2+ signalling pathway occurs at the level of hormone-induced inositol 1,4,5 trisphosphate (IP3 ) production and does not involve changes in the sensitivity of the IP3 receptor or size of internal Ca2+ stores. We suggest that prolonged and aberrant hormone-evoked Ca2+ increases may stimulate the production of mitochondrial reactive oxygen species and contribute to alcohol-induced hepatocyte injury. ABSTRACT: 'Adaptive' responses of the liver to chronic alcohol consumption may underlie the development of cell and tissue injury. Alcohol administration can perturb multiple signalling pathways including phosphoinositide-dependent cytosolic calcium ([Ca2+ ]i ) increases, which can adversely affect mitochondrial Ca2+ levels, reactive oxygen species production and energy metabolism. Our data indicate that chronic alcohol feeding induces a leftward shift in the dose-response for Ca2+ -mobilizing hormones resulting in more sustained and prolonged [Ca2+ ]i increases in both cultured hepatocytes and hepatocytes within the intact perfused liver. Ca2+ increases were initiated at lower hormone concentrations, and intercellular calcium wave propagation rates were faster in alcoholics compared to controls. Acute alcohol treatment (25 mm) completely inhibited hormone-induced calcium increases in control livers, but not after chronic alcohol-feeding, suggesting desensitization to the inhibitory actions of ethanol. Hormone-induced inositol 1,4,5 trisphosphate (IP3 ) accumulation and phospholipase C (PLC) activity were significantly potentiated in hepatocytes from alcohol-fed rats compared to controls. Removal of extracellular calcium, or chelation of intracellular calcium did not normalize the differences in hormone-stimulated PLC activity, indicating calcium-dependent PLCs are not upregulated by alcohol. We propose that the liver 'adapts' to chronic alcohol exposure by increasing hormone-dependent IP3 formation, leading to aberrant calcium increases, which may contribute to hepatocyte injury.
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Affiliation(s)
- Paula J Bartlett
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Anil Noronha Antony
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Amit Agarwal
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Mauricette Hilly
- INSERM UMR-S 757, Université de Paris-Sud, bât 443, 91405, Orsay, France
| | - Victoria L Prince
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Laurent Combettes
- INSERM UMR-S 757, Université de Paris-Sud, bât 443, 91405, Orsay, France
| | - Jan B Hoek
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Lawrence D Gaspers
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
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20
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Zhao P, Ye T, Yan X, Hu X, Liu P, Wang X. HMGB1 release by H 2O 2-induced hepatocytes is regulated through calcium overload and 58-F interference. Cell Death Discov 2017; 3:17008. [PMID: 28417016 PMCID: PMC5385391 DOI: 10.1038/cddiscovery.2017.8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 01/10/2017] [Indexed: 12/14/2022] Open
Abstract
HMGB1 is passively released by injured or dying cells and aggravates inflammatory processes. The release of HMGB1 and calcium overload have each been reported to be important mediators of H2O2-induced injury. However, a potential connection between these two processes remains to be elucidated. In the present study, we employed H2O2-induced hepatocytes to investigate how calcium overload takes place during cellular injury and how the extracellular release of HMGB1 is regulated by this overload. In addition, we investigated the use of 58-F, a flavanone extracted from Ophiopogon japonicus, as a potential therapeutic drug. We show that the PLCγ1-IP3R-SOC signalling pathway participates in the H2O2-induced disturbance of calcium homoeostasis and leads to calcium overload in hepatocytes. After a rise in intracellular calcium, two calcium-dependent enzymes, PKCα and CaMKIV, are activated and translocated from the cytoplasm to the nucleus to modify HMGB1 phosphorylation. In turn, this promotes HMGB1 translocation from the nucleus to the cytoplasm and subsequent extracellular release. 58-F effectively rescued the hepatocytes by suppressing the PLCγ1-IP3R-SOC signalling pathway and decreasing the calcium concentration in cells, thus reducing HMGB1 release.
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Affiliation(s)
- Pei Zhao
- The Public Experiment Platform, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Tingjie Ye
- Department of Biology, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Xiaofeng Yan
- Department of Biology, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Xudong Hu
- Department of Biology, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Ping Liu
- Key Laboratory of Liver and Kidney Diseases (Ministry of Education), Institute of Liver Diseases, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.,E-institute of Shanghai Municipal Education Commission, Shanghai 201203, China
| | - Xiaoling Wang
- Department of Biology, School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
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21
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Dougoud M, Vinckenbosch L, Mazza C, Schwaller B, Pecze L. The Effect of Gap Junctional Coupling on the Spatiotemporal Patterns of Ca2+ Signals and the Harmonization of Ca2+-Related Cellular Responses. PLoS Comput Biol 2016; 12:e1005295. [PMID: 28027293 PMCID: PMC5226819 DOI: 10.1371/journal.pcbi.1005295] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 01/11/2017] [Accepted: 12/08/2016] [Indexed: 12/18/2022] Open
Abstract
Calcium ions (Ca2+) are important mediators of a great variety of cellular activities e.g. in response to an agonist activation of a receptor. The magnitude of a cellular response is often encoded by frequency modulation of Ca2+ oscillations and correlated with the stimulation intensity. The stimulation intensity highly depends on the sensitivity of a cell to a certain agonist. In some cases, it is essential that neighboring cells produce a similar and synchronized response to an agonist despite their different sensitivity. In order to decipher the presumed function of Ca2+ waves spreading among connecting cells, a mathematical model was developed. This model allows to numerically modifying the connectivity probability between neighboring cells, the permeability of gap junctions and the individual sensitivity of cells to an agonist. Here, we show numerically that strong gap junctional coupling between neighbors ensures an equilibrated response to agonist stimulation via formation of Ca2+ phase waves, i.e. a less sensitive neighbor will produce the same or similar Ca2+ signal as its highly sensitive neighbor. The most sensitive cells within an ensemble are the wave initiator cells. The Ca2+ wave in the cytoplasm is driven by a sensitization wave front in the endoplasmic reticulum. The wave velocity is proportional to the cellular sensitivity and to the strength of the coupling. The waves can form different patterns including circular rings and spirals. The observed pattern depends on the strength of noise, gap junctional permeability and the connectivity probability between neighboring cells. Our simulations reveal that one highly sensitive region gradually takes the lead within the entire noisy system by generating directed circular phase waves originating from this region. The calcium ion (Ca2+), a universal signaling molecule, is widely recognized to play a fundamental role in the regulation of various biological processes. Agonist–evoked Ca2+ signals often manifest as rhythmic changes in the cytosolic free Ca2+ concentration (ccyt) called Ca2+ oscillations. Stimuli intensity was found to be proportional to the oscillation frequency and the evoked down-steam cellular response. Stochastic receptor expression in individual cells in a cell population inevitably leads to individually different oscillation frequencies and individually different Ca2+-related cellular responses. However, in many organs, the neighboring cells have to overcome their individually different sensitivity and produce a synchronized response. Gap junctions are integral membrane structures that enable the direct cytoplasmic exchange of Ca2+ ions and InsP3 molecules between neighboring cells. By simulations, we were able to demonstrate how the strength of intercellular gap junctional coupling in relation to stimulus intensity can modify the spatiotemporal patterns of Ca2+ signals and harmonize the Ca2+-related cellular responses via synchronization of oscillation frequency. We demonstrate that the most sensitive cells are the wave initiator cells and that a highly sensitive region plays an important role in the determination of the Ca2+ phase wave direction. This sensitive region will then also progressively determine the global behavior of the entire system.
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Affiliation(s)
- Michaël Dougoud
- Department of Mathematics, University of Fribourg, Fribourg, Switzerland
| | - Laura Vinckenbosch
- Department of Mathematics, University of Fribourg, Fribourg, Switzerland
- University of Applied Sciences and Arts Western Switzerland // HES-SO, HEIG-VD, Yverdon-les-Bains, Switzerland
| | - Christian Mazza
- Department of Mathematics, University of Fribourg, Fribourg, Switzerland
| | - Beat Schwaller
- Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland
| | - László Pecze
- Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland
- * E-mail:
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22
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Feriod CN, Oliveira AG, Guerra MT, Nguyen L, Richards KM, Jurczak MJ, Ruan HB, Camporez JP, Yang X, Shulman GI, Bennett AM, Nathanson MH, Ehrlich BE. Hepatic Inositol 1,4,5 Trisphosphate Receptor Type 1 Mediates Fatty Liver. Hepatol Commun 2016; 1:23-35. [PMID: 28966992 PMCID: PMC5613674 DOI: 10.1002/hep4.1012] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Fatty liver is the most common type of liver disease, affecting nearly one third of the US population and more than half a billion people worldwide. Abnormalities in ER calcium handling and mitochondrial function each have been implicated in abnormal lipid droplet formation. Here we show that the type 1 isoform of the inositol 1,4,5-trisphosphate receptor (InsP3R1) specifically links ER calcium release to mitochondrial calcium signaling and lipid droplet formation in hepatocytes. Moreover, liver-specific InsP3R1 knockout mice have impaired mitochondrial calcium signaling, decreased hepatic triglycerides, reduced lipid droplet formation and are resistant to development of fatty liver. Patients with non-alcoholic steatohepatitis, the most malignant form of fatty liver, have increased hepatic expression of InsP3R1 and the extent of ER-mitochondrial co-localization correlates with the degree of steatosis in human liver biopsies. CONCLUSION InsP3R1 plays a central role in lipid droplet formation in hepatocytes and the data suggest that it is involved in the development of human fatty liver disease.
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Affiliation(s)
- Colleen N Feriod
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, CT 06520.,Department of Pharmacology, Yale University School of Medicine New Haven, CT 06520
| | - Andre Gustavo Oliveira
- Section of Digestive Diseases, Internal Medicine, Yale University School of Medicine New Haven, CT 06520
| | - Mateus T Guerra
- Section of Digestive Diseases, Internal Medicine, Yale University School of Medicine New Haven, CT 06520
| | - Lily Nguyen
- Department of Pharmacology, Yale University School of Medicine New Haven, CT 06520
| | | | - Michael J Jurczak
- Department of Internal Medicine, Yale University School of Medicine New Haven, CT 06520
| | - Hai-Bin Ruan
- Department of Comparative Medicine, Yale University School of Medicine New Haven, CT 06520.,Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine New Haven, CT 06520
| | - Joao Paulo Camporez
- Department of Internal Medicine, Yale University School of Medicine New Haven, CT 06520
| | - Xiaoyong Yang
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, CT 06520.,Department of Comparative Medicine, Yale University School of Medicine New Haven, CT 06520.,Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine New Haven, CT 06520
| | - Gerald I Shulman
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, CT 06520.,Department of Internal Medicine, Yale University School of Medicine New Haven, CT 06520.,Howard Hughes Medical Institute, Yale University School of Medicine New Haven, CT 06520
| | - Anton M Bennett
- Department of Pharmacology, Yale University School of Medicine New Haven, CT 06520.,Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University School of Medicine New Haven, CT 06520
| | - Michael H Nathanson
- Section of Digestive Diseases, Internal Medicine, Yale University School of Medicine New Haven, CT 06520
| | - Barbara E Ehrlich
- Department of Cellular and Molecular Physiology, Yale University School of Medicine New Haven, CT 06520.,Department of Pharmacology, Yale University School of Medicine New Haven, CT 06520
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23
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Berridge MJ. The Inositol Trisphosphate/Calcium Signaling Pathway in Health and Disease. Physiol Rev 2016; 96:1261-96. [DOI: 10.1152/physrev.00006.2016] [Citation(s) in RCA: 377] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Many cellular functions are regulated by calcium (Ca2+) signals that are generated by different signaling pathways. One of these is the inositol 1,4,5-trisphosphate/calcium (InsP3/Ca2+) signaling pathway that operates through either primary or modulatory mechanisms. In its primary role, it generates the Ca2+ that acts directly to control processes such as metabolism, secretion, fertilization, proliferation, and smooth muscle contraction. Its modulatory role occurs in excitable cells where it modulates the primary Ca2+ signal generated by the entry of Ca2+ through voltage-operated channels that releases Ca2+ from ryanodine receptors (RYRs) on the internal stores. In carrying out this modulatory role, the InsP3/Ca2+ signaling pathway induces subtle changes in the generation and function of the voltage-dependent primary Ca2+ signal. Changes in the nature of both the primary and modulatory roles of InsP3/Ca2+ signaling are a contributory factor responsible for the onset of a large number human diseases.
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Affiliation(s)
- Michael J. Berridge
- Laboratory of Molecular Signalling, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, United Kingdom
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The effect of chronic alcohol consumption on mitochondrial calcium handling in hepatocytes. Biochem J 2016; 473:3903-3921. [PMID: 27582500 DOI: 10.1042/bcj20160255] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 08/31/2016] [Indexed: 01/08/2023]
Abstract
The damage to liver mitochondria is universally observed in both humans and animal models after excessive alcohol consumption. Acute alcohol treatment has been shown to stimulate calcium (Ca2+) release from internal stores in hepatocytes. The resultant increase in cytosolic Ca2+ is expected to be accumulated by neighboring mitochondria, which could potentially lead to mitochondrial Ca2+ overload and injury. Our data indicate that total and free mitochondrial matrix Ca2+ levels are, indeed, elevated in hepatocytes isolated from alcohol-fed rats compared with their pair-fed control littermates. In permeabilized hepatocytes, the rates of mitochondrial Ca2+ uptake were substantially increased after chronic alcohol feeding, whereas those of mitochondrial Ca2+ efflux were decreased. The changes in mitochondrial Ca2+ handling could be explained by an up-regulation of the mitochondrial Ca2+ uniporter and loss of a cyclosporin A-sensitive Ca2+ transport pathway. In intact cells, hormone-induced increases in mitochondrial Ca2+ declined at slower rates leading to more prolonged elevations of matrix Ca2+ in the alcohol-fed group compared with controls. Moreover, treatment with submaximal concentrations of Ca2+-mobilizing hormones markedly increased the levels of mitochondrial reactive oxygen species (ROS) in hepatocytes from alcohol-fed rats, but did not affect ROS levels in controls. The changes in mitochondrial Ca2+ handling are expected to buffer and attenuate cytosolic Ca2+ increases induced by acute alcohol exposure or hormone stimulation. However, these alterations in mitochondrial Ca2+ handling may also lead to Ca2+ overload during cytosolic Ca2+ increases, which may stimulate the production of mitochondrial ROS, and thus contribute to alcohol-induced liver injury.
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Andreeva LA, Grishina EV, Sergeev AI, Lobanov AV, Slastcheva GA, Rykov VA, Temyakov AV, Dynnik VV. Emergence of acetylcholine resistance and loss of rhythmic activity associated with the development of hypertension, obesity, and type 2 diabetes. BIOCHEMISTRY (MOSCOW) SUPPLEMENT SERIES A: MEMBRANE AND CELL BIOLOGY 2016; 10:199-206. [DOI: 10.1134/s1990747816020033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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26
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Liu X, Li X. Systematical bifurcation analysis of an intracellular calcium oscillation model. Biosystems 2016; 145:33-40. [DOI: 10.1016/j.biosystems.2016.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 04/05/2016] [Accepted: 04/28/2016] [Indexed: 11/16/2022]
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Pecze L, Blum W, Schwaller B. Routes of Ca2+ Shuttling during Ca2+ Oscillations: FOCUS ON THE ROLE OF MITOCHONDRIAL Ca2+ HANDLING AND CYTOSOLIC Ca2+ BUFFERS. J Biol Chem 2015; 290:28214-28230. [PMID: 26396196 PMCID: PMC4653679 DOI: 10.1074/jbc.m115.663179] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Indexed: 01/29/2023] Open
Abstract
In some cell types, Ca2+ oscillations are strictly dependent on Ca2+ influx across the plasma membrane, whereas in others, oscillations also persist in the absence of Ca2+ influx. We observed that, in primary mesothelial cells, the plasmalemmal Ca2+ influx played a pivotal role. However, when the Ca2+ transport across the plasma membrane by the “lanthanum insulation method” was blocked prior to the induction of the serum-induced Ca2+ oscillations, mitochondrial Ca2+ transport was found to be able to substitute for the plasmalemmal Ca2+ exchange function, thus rendering the oscillations independent of extracellular Ca2+. However, in a physiological situation, the Ca2+-buffering capacity of mitochondria was found not to be essential for Ca2+ oscillations. Moreover, brief spontaneous Ca2+ changes were observed in the mitochondrial Ca2+ concentration without apparent changes in the cytosolic Ca2+ concentration, indicating the presence of a mitochondrial autonomous Ca2+ signaling mechanism. In the presence of calretinin, a Ca2+-buffering protein, the amplitude of cytosolic spikes during oscillations was decreased, and the amount of Ca2+ ions taken up by mitochondria was reduced. Thus, the increased calretinin expression observed in mesothelioma cells and in certain colon cancer might be correlated to the increased resistance of these tumor cells to proapoptotic/pronecrotic signals. We identified and characterized (experimentally and by modeling) three Ca2+ shuttling pathways in primary mesothelial cells during Ca2+ oscillations: Ca2+ shuttled between (i) the endoplasmic reticulum (ER) and mitochondria, (ii) the ER and the extracellular space, and (iii) the ER and cytoplasmic Ca2+ buffers.
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Affiliation(s)
- László Pecze
- Anatomy, Department of Medicine, University of Fribourg, Route Albert-Gockel 1, CH-1700 Fribourg, Switzerland.
| | - Walter Blum
- Anatomy, Department of Medicine, University of Fribourg, Route Albert-Gockel 1, CH-1700 Fribourg, Switzerland
| | - Beat Schwaller
- Anatomy, Department of Medicine, University of Fribourg, Route Albert-Gockel 1, CH-1700 Fribourg, Switzerland
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Bartlett PJ, Metzger W, Gaspers LD, Thomas AP. Differential Regulation of Multiple Steps in Inositol 1,4,5-Trisphosphate Signaling by Protein Kinase C Shapes Hormone-stimulated Ca2+ Oscillations. J Biol Chem 2015; 290:18519-33. [PMID: 26078455 DOI: 10.1074/jbc.m115.657767] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Indexed: 11/06/2022] Open
Abstract
How Ca(2+) oscillations are generated and fine-tuned to yield versatile downstream responses remains to be elucidated. In hepatocytes, G protein-coupled receptor-linked Ca(2+) oscillations report signal strength via frequency, whereas Ca(2+) spike amplitude and wave velocity remain constant. IP3 uncaging also triggers oscillatory Ca(2+) release, but, in contrast to hormones, Ca(2+) spike amplitude, width, and wave velocity were dependent on [IP3] and were not perturbed by phospholipase C (PLC) inhibition. These data indicate that oscillations elicited by IP3 uncaging are driven by the biphasic regulation of the IP3 receptor by Ca(2+), and, unlike hormone-dependent responses, do not require PLC. Removal of extracellular Ca(2+) did not perturb Ca(2+) oscillations elicited by IP3 uncaging, indicating that reloading of endoplasmic reticulum stores via plasma membrane Ca(2+) influx does not entrain the signal. Activation and inhibition of PKC attenuated hormone-induced Ca(2+) oscillations but had no effect on Ca(2+) increases induced by uncaging IP3. Importantly, PKC activation and inhibition differentially affected Ca(2+) spike frequencies and kinetics. PKC activation amplifies negative feedback loops at the level of G protein-coupled receptor PLC activity and/or IP3 metabolism to attenuate IP3 levels and suppress the generation of Ca(2+) oscillations. Inhibition of PKC relieves negative feedback regulation of IP3 accumulation and, thereby, shifts Ca(2+) oscillations toward sustained responses or dramatically prolonged spikes. PKC down-regulation attenuates phenylephrine-induced Ca(2+) wave velocity, whereas responses to IP3 uncaging are enhanced. The ability to assess Ca(2+) responses in the absence of PLC activity indicates that IP3 receptor modulation by PKC regulates Ca(2+) release and wave velocity.
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Affiliation(s)
- Paula J Bartlett
- From the Department of Pharmacology and Physiology, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, New Jersey 07103
| | - Walson Metzger
- From the Department of Pharmacology and Physiology, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, New Jersey 07103
| | - Lawrence D Gaspers
- From the Department of Pharmacology and Physiology, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, New Jersey 07103
| | - Andrew P Thomas
- From the Department of Pharmacology and Physiology, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, New Jersey 07103
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Pecze L, Schwaller B. Characterization and modeling of Ca2+ oscillations in mouse primary mesothelial cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:632-45. [DOI: 10.1016/j.bbamcr.2014.12.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/16/2014] [Accepted: 12/19/2014] [Indexed: 10/24/2022]
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30
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Gaspers LD, Bartlett PJ, Politi A, Burnett P, Metzger W, Johnston J, Joseph SK, Höfer T, Thomas AP. Hormone-induced calcium oscillations depend on cross-coupling with inositol 1,4,5-trisphosphate oscillations. Cell Rep 2014; 9:1209-18. [PMID: 25456123 PMCID: PMC6469397 DOI: 10.1016/j.celrep.2014.10.033] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 08/08/2014] [Accepted: 10/10/2014] [Indexed: 11/29/2022] Open
Abstract
Receptor-mediated oscillations in cytosolic Ca2+ concentration ([Ca2+]i) could originate either directly from an autonomous Ca2+ feedback oscillator at the inositol 1,4,5-trisphosphate (IP3) receptor or as a secondary consequence of IP3 oscillations driven by Ca2+ feedback on IP3 metabolism. It is challenging to discriminate these alternatives, because IP3 fluctuations could drive Ca2+ oscillations or could just be a secondary response to the [Ca2+]i spikes. To investigate this problem, we constructed a recombinant IP3 buffer using type-I IP3 receptor ligand-binding domain fused to GFP (GFP-LBD), which buffers IP3 in the physiological range. This IP3 buffer slows hormone-induced [IP3] dynamics without changing steady-state [IP3]. GFP-LBD perturbed [Ca2+]i oscillations in a dose-dependent manner: it decreased both the rate of [Ca2+]i rise and the speed of Ca2+ wave propagation and, at high levels, abolished [Ca2+]i oscillations completely. These data, together with computational modeling, demonstrate that IP3 dynamics play a fundamental role in generating [Ca2+]i oscillations and waves. Gaspers et al. use a genetically encoded IP3 buffer to suppress IP3 dynamics during hormonal stimulation. Using this approach, they find that positive feedback of Ca2+ on IP3 formation is an essential component, generating long-period, baseline-separated Ca2+ oscillations and intracellular Ca2+ waves.
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Affiliation(s)
- Lawrence D Gaspers
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, USA
| | - Paula J Bartlett
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, USA
| | - Antonio Politi
- German Cancer Research Center, Division of Theoretical Systems Biology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Paul Burnett
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, USA
| | - Walson Metzger
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, USA
| | - Jane Johnston
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, USA
| | - Suresh K Joseph
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Thomas Höfer
- German Cancer Research Center, Division of Theoretical Systems Biology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Andrew P Thomas
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, USA.
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31
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Cicek FA, Ozgur EO, Ozgur E, Ugur M. The interplay between plasma membrane and endoplasmic reticulum Ca(2+)ATPases in agonist-induced temporal Ca(2+) dynamics. J Bioenerg Biomembr 2014; 46:503-10. [PMID: 25331516 DOI: 10.1007/s10863-014-9587-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 09/25/2014] [Indexed: 01/20/2023]
Abstract
A change in the intracellular free Ca(2+) concentration ([Ca(2+)]i) functions as a transmitter for signal transduction and shows a broad temporal pattern. Even genetically homogeneous cell types show different Ca(2+) response patterns under permanent agonist stimulation. In Ca(2+) signaling, the dynamics of the Ca(2+) release from the Ca(2+) channels during continuous agonist stimulation and the simultaneous effect of the pumps are unclear. In this study, the dynamic interaction of the Ca(2+) ATPases in the plasma membrane (PMCA) and the endoplasmic reticulum membrane (SERCA) during continuous ACh stimulation is monitored using Fluo-3 and Fura-2 loaded HEK 293 cells. We characterize Ca(2+) release patterns at the sub-maximal and maximal stimulation doses in the absence of extracellular Ca(2+). We analyze the responses regarding their types, oscillation frequency and response times. La(3+) (PMCA blocker) do not change the frequency and time courses in sub-maximal ACh treatment, while with the maximal stimulation oscillation frequency increase as oscillations superimpose on robust release, and response time of [Ca(2+)]i is elongated. A similar effect of La(3+) is observed in quantal Ca(2+) release phenomenon. In the presence of CPA, a SERCA blocker, oscillations are completely abolished, but response time does not change. We also observe that during continuous receptor stimulation, Ca(2+) release do not cease. These data may suggest that Ca(2+) release continues during agonist stimulation, but SERCA and PMCA form a new steady state and return [Ca(2+)]i to its physiological concentration.
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Affiliation(s)
- Figen Amber Cicek
- Department of Biophysics, Faculty of Medicine, Cukurova University, Adana, Turkey,
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32
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Park HW, Park H, Semple IA, Jang I, Ro SH, Kim M, Cazares VA, Stuenkel EL, Kim JJ, Kim JS, Lee JH. Pharmacological correction of obesity-induced autophagy arrest using calcium channel blockers. Nat Commun 2014; 5:4834. [PMID: 25189398 PMCID: PMC4157315 DOI: 10.1038/ncomms5834] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 07/29/2014] [Indexed: 12/16/2022] Open
Abstract
Autophagy deregulation during obesity contributes to the pathogenesis of diverse metabolic disorders. However, without understanding the molecular mechanism of obesity interference in autophagy, development of therapeutic strategies for correcting such defects in obese individuals is challenging. Here we show that chronic increase of cytosolic calcium concentration in hepatocytes upon obesity and lipotoxicity attenuates autophagic flux by preventing the fusion between autophagosomes and lysosomes. As a pharmacological approach to restore cytosolic calcium homeostasis in vivo, we administered the clinically approved calcium channel blocker verapamil to obese mice. Such treatment successfully increases autophagosome-lysosome fusion in liver, preventing accumulation of protein inclusions and lipid droplets and suppressing inflammation and insulin resistance. As calcium channel blockers have been safely used in clinics for the treatment of hypertension for more than thirty years, our results suggest they may be a safe therapeutic option for restoring autophagic flux and treating metabolic pathologies in obese patients.
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Affiliation(s)
- Hwan-Woo Park
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Haeli Park
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Ian A Semple
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Insook Jang
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Seung-Hyun Ro
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Myungjin Kim
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Victor A Cazares
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Edward L Stuenkel
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Jung-Jae Kim
- School of Computer Engineering, Nanyang Technological University, Singapore 639798, Singapore
| | - Jeong Sig Kim
- 1] Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA [2] Department of Obstetrics and Gynecology, Soonchunhyang University Seoul Hospital, Seoul 140-743, Republic of Korea
| | - Jun Hee Lee
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
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Thurley K, Tovey SC, Moenke G, Prince VL, Meena A, Thomas AP, Skupin A, Taylor CW, Falcke M. Reliable encoding of stimulus intensities within random sequences of intracellular Ca2+ spikes. Sci Signal 2014; 7:ra59. [PMID: 24962706 PMCID: PMC4092318 DOI: 10.1126/scisignal.2005237] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ca(2+) is a ubiquitous intracellular messenger that regulates diverse cellular activities. Extracellular stimuli often evoke sequences of intracellular Ca(2+) spikes, and spike frequency may encode stimulus intensity. However, the timing of spikes within a cell is random because each interspike interval has a large stochastic component. In human embryonic kidney (HEK) 293 cells and rat primary hepatocytes, we found that the average interspike interval also varied between individual cells. To evaluate how individual cells reliably encoded stimuli when Ca(2+) spikes exhibited such unpredictability, we combined Ca(2+) imaging of single cells with mathematical analyses of the Ca(2+) spikes evoked by receptors that stimulate formation of inositol 1,4,5-trisphosphate (IP3). This analysis revealed that signal-to-noise ratios were improved by slow recovery from feedback inhibition of Ca(2+) spiking operating at the whole-cell level and that they were robust against perturbations of the signaling pathway. Despite variability in the frequency of Ca(2+) spikes between cells, steps in stimulus intensity caused the stochastic period of the interspike interval to change by the same factor in all cells. These fold changes reliably encoded changes in stimulus intensity, and they resulted in an exponential dependence of average interspike interval on stimulation strength. We conclude that Ca(2+) spikes enable reliable signaling in a cell population despite randomness and cell-to-cell variability, because global feedback reduces noise, and changes in stimulus intensity are represented by fold changes in the stochastic period of the interspike interval.
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Affiliation(s)
- Kevin Thurley
- Mathematical Cell Physiology, Max Delbrück Center for Molecular Medicine, Robert Rössle Straße 10, Berlin 13125, Germany. Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK. Institute for Theoretical Biology, Charité-Universitätsmedizin Berlin, Invalidenstraße 43, Berlin 10115, Germany
| | - Stephen C Tovey
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Gregor Moenke
- Mathematical Cell Physiology, Max Delbrück Center for Molecular Medicine, Robert Rössle Straße 10, Berlin 13125, Germany
| | - Victoria L Prince
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, USA
| | - Abha Meena
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Andrew P Thomas
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, USA
| | - Alexander Skupin
- Luxembourg Centre for Systems Biomedicine, 7 Avenue des Hauts Fourneaux, Esch sur Alzette 4362, Luxembourg. National Center for Microscopy and Imaging Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Colin W Taylor
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK.
| | - Martin Falcke
- Mathematical Cell Physiology, Max Delbrück Center for Molecular Medicine, Robert Rössle Straße 10, Berlin 13125, Germany. Department of Physics, Humboldt University Berlin, Newtonstraße 15, Berlin 12489, Germany.
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Bartlett PJ, Gaspers LD, Pierobon N, Thomas AP. Calcium-dependent regulation of glucose homeostasis in the liver. Cell Calcium 2014; 55:306-16. [PMID: 24630174 DOI: 10.1016/j.ceca.2014.02.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Revised: 02/07/2014] [Accepted: 02/08/2014] [Indexed: 02/09/2023]
Abstract
A major role of the liver is to integrate multiple signals to maintain normal blood glucose levels. The balance between glucose storage and mobilization is primarily regulated by the counteracting effects of insulin and glucagon. However, numerous signals converge in the liver to ensure energy demand matches the physiological status of the organism. Many circulating hormones regulate glycogenolysis, gluconeogenesis and mitochondrial metabolism by calcium-dependent signaling mechanisms that manifest as cytosolic Ca(2+) oscillations. Stimulus-strength is encoded in the Ca(2+) oscillation frequency, and also by the range of intercellular Ca(2+) wave propagation in the intact liver. In this article, we describe how Ca(2+) oscillations and waves can regulate glucose output and oxidative metabolism in the intact liver; how multiple stimuli are decoded though Ca(2+) signaling at the organ level, and the implications of Ca(2+) signal dysregulation in diseases such as metabolic syndrome and non-alcoholic fatty liver disease.
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Affiliation(s)
- Paula J Bartlett
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA.
| | - Lawrence D Gaspers
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Nicola Pierobon
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
| | - Andrew P Thomas
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, USA
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Ishida S, Matsu-ura T, Fukami K, Michikawa T, Mikoshiba K. Phospholipase C-β1 and β4 contribute to non-genetic cell-to-cell variability in histamine-induced calcium signals in HeLa cells. PLoS One 2014; 9:e86410. [PMID: 24475116 PMCID: PMC3903530 DOI: 10.1371/journal.pone.0086410] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 12/12/2013] [Indexed: 11/18/2022] Open
Abstract
A uniform extracellular stimulus triggers cell-specific patterns of Ca(2+) signals, even in genetically identical cell populations. However, the underlying mechanism that generates the cell-to-cell variability remains unknown. We monitored cytosolic inositol 1,4,5-trisphosphate (IP3) concentration changes using a fluorescent IP3 sensor in single HeLa cells showing different patterns of histamine-induced Ca(2+) oscillations in terms of the time constant of Ca(2+) spike amplitude decay and the Ca(2+) oscillation frequency. HeLa cells stimulated with histamine exhibited a considerable variation in the temporal pattern of Ca(2+) signals and we found that there were cell-specific IP3 dynamics depending on the patterns of Ca(2+) signals. RT-PCR and western blot analyses showed that phospholipase C (PLC)-β1, -β3, -β4, -γ1, -δ3 and -ε were expressed at relatively high levels in HeLa cells. Small interfering RNA-mediated silencing of PLC isozymes revealed that PLC-β1 and PLC-β4 were specifically involved in the histamine-induced IP3 increases in HeLa cells. Modulation of IP3 dynamics by knockdown or overexpression of the isozymes PLC-β1 and PLC-β4 resulted in specific changes in the characteristics of Ca(2+) oscillations, such as the time constant of the temporal changes in the Ca(2+) spike amplitude and the Ca(2+) oscillation frequency, within the range of the cell-to-cell variability found in wild-type cell populations. These findings indicate that the heterogeneity in the process of IP3 production, rather than IP3-induced Ca(2+) release, can cause cell-to-cell variability in the patterns of Ca(2+) signals and that PLC-β1 and PLC-β4 contribute to generate cell-specific Ca(2+) signals evoked by G protein-coupled receptor stimulation.
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Affiliation(s)
- Sachiko Ishida
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Japan
| | - Toru Matsu-ura
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Japan
| | - Kiyoko Fukami
- Laboratory of Genome and Biosignal, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Takayuki Michikawa
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Japan
- Calcium Oscillation Project, ICORP-SORST, Japan Science and Technology Agency, Kawaguchi, Japan
- Laboratory for Behavioral Genetics, RIKEN Brain Science Institute, Wako, Japan
- * E-mail: (TM); (KM)
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Japan
- Calcium Oscillation Project, ICORP-SORST, Japan Science and Technology Agency, Kawaguchi, Japan
- * E-mail: (TM); (KM)
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Abstract
Intracellular free Ca(2+) ([Ca(2+)]i) is a highly versatile second messenger that regulates a wide range of functions in every type of cell and tissue. To achieve this versatility, the Ca(2+) signaling system operates in a variety of ways to regulate cellular processes that function over a wide dynamic range. This is particularly well exemplified for Ca(2+) signals in the liver, which modulate diverse and specialized functions such as bile secretion, glucose metabolism, cell proliferation, and apoptosis. These Ca(2+) signals are organized to control distinct cellular processes through tight spatial and temporal coordination of [Ca(2+)]i signals, both within and between cells. This article will review the machinery responsible for the formation of Ca(2+) signals in the liver, the types of subcellular, cellular, and intercellular signals that occur, the physiological role of Ca(2+) signaling in the liver, and the role of Ca(2+) signaling in liver disease.
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Affiliation(s)
- Maria Jimena Amaya
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
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Thompson JL, Shuttleworth TJ. Exploring the unique features of the ARC channel, a store-independent Orai channel. Channels (Austin) 2013; 7:364-73. [PMID: 24025406 DOI: 10.4161/chan.26156] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The discovery of the Orai proteins, and the identification of STIM1 as the molecule that regulates them, was based on their role in the agonist-activated store-operated entry of calcium via the CRAC channels. However, these same proteins are also essential components of the ARC channels responsible for a similar agonist-activated, but store-independent, arachidonic acid-regulated entry of calcium. The fact that these 2 biophysically similar calcium entry pathways frequently co-exist in the same cells suggests that they must each possess different features that allow them to function in distinct ways to regulate specific cellular activities. This review begins to address this question by describing recent findings characterizing the unique features of the ARC channels--their molecular composition, STIM1-dependent activation, and physiological activities--and the importance of defining such features for the accurate therapeutic targeting of these 2 Orai channel subtypes.
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Affiliation(s)
- Jill L Thompson
- Department of Pharmacology and Physiology; University of Rochester Medical Center; Rochester, NY USA
| | - Trevor J Shuttleworth
- Department of Pharmacology and Physiology; University of Rochester Medical Center; Rochester, NY USA
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Turovsky EA, Turovskaya MV, Dolgacheva LP, Zinchenko VP, Dynnik VV. Acetylcholine promotes Ca2+ and NO-oscillations in adipocytes implicating Ca2+→NO→cGMP→cADP-ribose→Ca2+ positive feedback loop--modulatory effects of norepinephrine and atrial natriuretic peptide. PLoS One 2013; 8:e63483. [PMID: 23696827 PMCID: PMC3656004 DOI: 10.1371/journal.pone.0063483] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 04/03/2013] [Indexed: 02/05/2023] Open
Abstract
PURPOSE This study investigated possible mechanisms of autoregulation of Ca(2+) signalling pathways in adipocytes responsible for Ca(2+) and NO oscillations and switching phenomena promoted by acetylcholine (ACh), norepinephrine (NE) and atrial natriuretic peptide (ANP). METHODS Fluorescent microscopy was used to detect changes in Ca(2+) and NO in cultures of rodent white adipocytes. Agonists and inhibitors were applied to characterize the involvement of various enzymes and Ca(2+)-channels in Ca(2+) signalling pathways. RESULTS ACh activating M3-muscarinic receptors and Gβγ protein dependent phosphatidylinositol 3 kinase induces Ca(2+) and NO oscillations in adipocytes. At low concentrations of ACh which are insufficient to induce oscillations, NE or α1, α2-adrenergic agonists act by amplifying the effect of ACh to promote Ca(2+) oscillations or switching phenomena. SNAP, 8-Br-cAMP, NAD and ANP may also produce similar set of dynamic regimes. These regimes arise from activation of the ryanodine receptor (RyR) with the implication of a long positive feedback loop (PFL): Ca(2+)→NO→cGMP→cADPR→Ca(2+), which determines periodic or steady operation of a short PFL based on Ca(2+)-induced Ca(2+) release via RyR by generating cADPR, a coagonist of Ca(2+) at the RyR. Interplay between these two loops may be responsible for the observed effects. Several other PFLs, based on activation of endothelial nitric oxide synthase or of protein kinase B by Ca(2+)-dependent kinases, may reinforce functioning of main PFL and enhance reliability. All observed regimes are independent of operation of the phospholipase C/Ca(2+)-signalling axis, which may be switched off due to negative feedback arising from phosphorylation of the inositol-3-phosphate receptor by protein kinase G. CONCLUSIONS This study presents a kinetic model of Ca(2+)-signalling system operating in adipocytes and integrating signals from various agonists, which describes it as multivariable multi feedback network with a family of nested positive feedback.
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Affiliation(s)
- Egor A. Turovsky
- Department of Intracellular Signalling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Mariya V. Turovskaya
- Department of Intracellular Signalling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Ludmila P. Dolgacheva
- Department of Intracellular Signalling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Valery P. Zinchenko
- Department of Intracellular Signalling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
| | - Vladimir V. Dynnik
- Department of Intracellular Signalling, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Russia
- Department of System Biochemistry, Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Russia
- * E-mail:
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Catacuzzeno L, Fioretti B, Franciolini F. A theoretical study on the role of Ca2+-activated K+ channels in the regulation of hormone-induced Ca2+ oscillations and their synchronization in adjacent cells. J Theor Biol 2012; 309:103-12. [DOI: 10.1016/j.jtbi.2012.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 05/04/2012] [Accepted: 05/07/2012] [Indexed: 11/24/2022]
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Termination of Ca²+ release for clustered IP₃R channels. PLoS Comput Biol 2012; 8:e1002485. [PMID: 22693433 PMCID: PMC3364945 DOI: 10.1371/journal.pcbi.1002485] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 03/07/2012] [Indexed: 01/17/2023] Open
Abstract
In many cell types, release of calcium ions is controlled by inositol 1,4,5-trisphosphate () receptor channels. Elevations in concentration after intracellular release through receptors (R) can either propagate in the form of waves spreading through the entire cell or produce spatially localized puffs. The appearance of waves and puffs is thought to implicate random initial openings of one or a few channels and subsequent activation of neighboring channels because of an “autocatalytic” feedback. It is much less clear, however, what determines the further time course of release, particularly since the lifetime is very different for waves (several seconds) and puffs (around 100 ms). Here we study the lifetime of signals and their dependence on residual microdomains. Our general idea is that microdomains are dynamical and mediate the effect of other physiological processes. Specifically, we focus on the mechanism by which binding proteins (buffers) alter the lifetime of signals. We use stochastic simulations of channel gating coupled to a coarse-grained description for the concentration. To describe the concentration in a phenomenological way, we here introduce a differential equation, which reflects the buffer characteristics by a few effective parameters. This non-stationary model for microdomains gives deep insight into the dynamical differences between puffs and waves. It provides a novel explanation for the different lifetimes of puffs and waves and suggests that puffs are terminated by inhibition while unbinding is responsible for termination of waves. Thus our analysis hints at an additional role of and shows how cells can make use of the full complexity in R gating behavior to achieve different signals. Calcium signals are important for a host of cellular processes such as neurotransmitter release, cell contraction and gene expression. While the principles of activation and spreading of calcium signals have been largely understood, it is much less clear how their spatio-temporal appearance is shaped. This issue is of high relevance since the spatio-temporal signature is thought to carry the information content. In our paper we study the dynamical mechanisms that determine the time course of calcium release from receptor channels. We use a stochastic channel description combined with a recently developed model for the distribution of released calcium in a microdomain. The simulations uncover a complex control mechanism, which allows for the tuning of release from short frequent puffs to extended and less frequent wave-like release. Unexpectedly, the model predicts that for wave-like release the dissociation of from the receptors leads to termination of the calcium signal. This effect relies on a well-known gating property of R channels, which earlier has been regarded as superfluous in studies for groups of channels. Our results also provide a missing link to understand cellular response to calcium-binding proteins and present a novel mechanism for information processing by R channels.
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Thurley K, Smith IF, Tovey SC, Taylor CW, Parker I, Falcke M. Timescales of IP(3)-evoked Ca(2+) spikes emerge from Ca(2+) puffs only at the cellular level. Biophys J 2012; 101:2638-44. [PMID: 22261051 DOI: 10.1016/j.bpj.2011.10.030] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 09/29/2011] [Accepted: 10/03/2011] [Indexed: 10/14/2022] Open
Abstract
The behavior of biological systems is determined by the properties of their component molecules, but the interactions are usually too complex to understand fully how molecular behavior generates cellular behavior. Ca(2+) signaling by inositol trisphosphate receptors (IP(3)R) offers an opportunity to understand this relationship because the cellular behavior is defined largely by Ca(2+)-mediated interactions between IP(3)R. Ca(2+) released by a cluster of IP(3)R (giving a local Ca(2+) puff) diffuses and ignites the behavior of neighboring clusters (to give repetitive global Ca(2+) spikes). We use total internal reflection fluorescence microscopy of two mammalian cell lines to define the temporal relationships between Ca(2+) puffs (interpuff intervals, IPI) and Ca(2+) spikes (interspike intervals) evoked by flash photolysis of caged IP(3). We find that IPI are much shorter than interspike intervals, that puff activity is stochastic with a recovery time that is much shorter than the refractory period of the cell, and that IPI are not periodic. We conclude that Ca(2+) spikes do not arise from oscillatory dynamics of IP(3)R clusters, but that repetitive Ca(2+) spiking with its longer timescales is an emergent property of the dynamics of the whole cluster array.
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Affiliation(s)
- Kevin Thurley
- Mathematical Cell Physiology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.
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Gaspers LD, Mémin E, Thomas AP. Calcium-dependent physiologic and pathologic stimulus-metabolic response coupling in hepatocytes. Cell Calcium 2012; 52:93-102. [PMID: 22564906 DOI: 10.1016/j.ceca.2012.04.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 04/13/2012] [Accepted: 04/16/2012] [Indexed: 01/19/2023]
Abstract
A recurrent paradigm in calcium signaling is the coordination of the target response of the calcium signal with activation of metabolic energy production to support that response. This occurs in many tissues, including cardiac and skeletal muscle where contractile activity and ATP production are coordinately regulated by the frequency and amplitude of calcium transients, endocrine and exocrine cells that use calcium to drive the secretory process, and hepatocytes where the downstream targets of calcium include both catabolic and anabolic processes. The primary mechanism by which calcium enhances the capacity for energy production is through calcium-dependent stimulation of mitochondrial oxidative metabolism, achieved by increasing NADH production and respiratory chain flux. Although this enhances energy supply, it also has the potential for deleterious consequences resulting from increased generation of reactive oxygen species (ROS). The negative consequences of calcium-dependent mitochondrial activation can be ameliorated when the underlying cytosolic calcium signals occur as brief calcium spikes or oscillations, with signal strength encoded through the spike frequency (frequency modulation). Frequency modulation increases signal fidelity, and reduces pathological effects of calcium, including excess mitochondrial ROS production and apoptotic or necrotic outcomes. The present article reviews these issues using data obtained in hepatocytes under physiologic and pathologic conditions.
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Affiliation(s)
- Lawrence D Gaspers
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, Newark, NJ 07103, United States.
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Bespyatykh AY, Burlakova OV, Golichenkov VA. Dynamics of the calcium ion level in rat hepatocytes primary cultures and its age-related changes. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2012; 441:421-3. [PMID: 22227696 DOI: 10.1134/s0012496611060196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Indexed: 11/22/2022]
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Abstract
The field of agonist-activated Ca(2+) entry in non-excitable cells underwent a revolution some 5 years ago with the discovery of the Orai proteins as the essential pore-forming components of the low-conductance, highly Ca(2+)-selective CRAC channels whose activation is dependent on depletion of intracellular stores. Mammals possess three distinct Orai proteins (Orai1, 2 and 3) of which Orai3 is unique to this class, apparently evolving from Orai1. However, the sequence of Orai3 shows marked differences from that of Orai1, particularly in those regions of the protein outside of the essential pore-forming domains. Correspondingly, studies from several different groups have indicated that the inclusion of Orai3 is associated with the appearance of conductances that display unique features in their gating, selectivity, regulation and mode of activation. In this Topical Review, these features are discussed with the purpose of proposing that the evolutionary appearance of Orai3 in mammals, and the consequent development of conductances displaying novel properties - whether formed by Orai3 alone or in conjunction with the other Orai proteins - is associated with the specific role of this member of the Orai family in a unique range of distinct cellular activities.
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Affiliation(s)
- Trevor J Shuttleworth
- Department of Pharmacology and Physiology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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The hepatitis B virus X protein elevates cytosolic calcium signals by modulating mitochondrial calcium uptake. J Virol 2011; 86:313-27. [PMID: 22031934 DOI: 10.1128/jvi.06442-11] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Chronic hepatitis B virus (HBV) infections are associated with the development of hepatocellular carcinoma (HCC). The HBV X protein (HBx) is thought to play an important role in the development of HBV-associated HCC. One fundamental HBx function is elevation of cytosolic calcium signals; this HBx activity has been linked to HBx stimulation of cell proliferation and transcription pathways, as well as HBV replication. Exactly how HBx elevates cytosolic calcium signals is not clear. The studies described here show that HBx stimulates calcium entry into cells, resulting in an increased plateau level of inositol 1,4,5-triphosphate (IP3)-linked calcium signals. This increased calcium plateau can be inhibited by blocking mitochondrial calcium uptake and store-operated calcium entry (SOCE). Blocking SOCE also reduced HBV replication. Finally, these studies also demonstrate that there is increased mitochondrial calcium uptake in HBx-expressing cells. Cumulatively, these studies suggest that HBx can increase mitochondrial calcium uptake and promote increased SOCE to sustain higher cytosolic calcium and stimulate HBV replication.
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Fundamental properties of Ca2+ signals. Biochim Biophys Acta Gen Subj 2011; 1820:1185-94. [PMID: 22040723 DOI: 10.1016/j.bbagen.2011.10.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 10/16/2011] [Accepted: 10/17/2011] [Indexed: 11/21/2022]
Abstract
BACKGROUND Ca2+ is a ubiquitous and versatile second messenger that transmits information through changes of the cytosolic Ca2+ concentration. Recent investigations changed basic ideas on the dynamic character of Ca2+ signals and challenge traditional ideas on information transmission. SCOPE OF REVIEW We present recent findings on key characteristics of the cytosolic Ca2+ dynamics and theoretical concepts that explain the wide range of experimentally observed Ca2+ signals. Further, we relate properties of the dynamical regulation of the cytosolic Ca2+ concentration to ideas about information transmission by stochastic signals. MAJOR CONCLUSIONS We demonstrate the importance of the hierarchal arrangement of Ca2+ release sites on the emergence of cellular Ca2+ spikes. Stochastic Ca2+ signals are functionally robust and adaptive to changing environmental conditions. Fluctuations of interspike intervals (ISIs) and the moment relation derived from ISI distributions contain information on the channel cluster open probability and on pathway properties. GENERAL SIGNIFICANCE Robust and reliable signal transduction pathways that entail Ca2+ dynamics are essential for eukaryotic organisms. Moreover, we expect that the design of a stochastic mechanism which provides robustness and adaptivity will be found also in other biological systems. Ca2+ dynamics demonstrate that the fluctuations of cellular signals contain information on molecular behavior. This article is part of a Special Issue entitled Biochemical, biophysical and genetic approaches to intracellular calcium signaling.
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Thompson JL, Shuttleworth TJ. Orai channel-dependent activation of phospholipase C-δ: a novel mechanism for the effects of calcium entry on calcium oscillations. J Physiol 2011; 589:5057-69. [PMID: 21878525 DOI: 10.1113/jphysiol.2011.214437] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The frequency of oscillatory Ca(2+) signals is a major determinant in the selective activation of discrete downstream responses in non-excitable cells. An important modulator of this oscillation frequency is known to be the rate of agonist-activated Ca(2+) entry. However precisely how this is achieved and the respective roles of store-operated versus store-independent Ca(2+) entry pathways in achieving this are unclear. Here, we examine the possibility that a direct stimulation of a phospholipase C (PLC) by the entering Ca(2+) can induce a modulation of Ca(2+) oscillation frequency, and examine the roles of the endogenous store-operated and store-independent Orai channels (CRAC and ARC channels, respectively) in such a mechanism. Using the decline in the magnitude of currents through expressed PIP(2)-dependent Kir2.1 channels as a sensitive assay for PLC activity, we show that simple global increases in Ca(2+) concentrations over the physiological range do not significantly affect PLC activity. Similarly, maximal activation of endogenous CRAC channels also fails to affect PLC activity. In contrast, equivalent activation of endogenous ARC channels resulted in a 10-fold increase in the measured rate of PIP(2) depletion. Further experiments show that this effect is strictly dependent on the Ca(2+) entering via these channels, rather than the gating of the channels or the arachidonic acid used to activate them, and that it reflects the activation of a PLCδ by local Ca(2+) concentrations immediately adjacent to the active channels. Finally, based on the effects of expression of either a dominant-negative mutant Orai3 that is an essential component of the ARC channel, or a catalytically compromised mutant PLCδ, it was shown that this specific action of the store-independent ARC channel-mediated Ca(2+) entry on PLCδ has a significant impact on the oscillation frequency of the Ca(2+) signals activated by low concentrations of agonist.
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Affiliation(s)
- Jill L Thompson
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
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Schweizer N, Kummer U, Hercht H, Braunbeck T. Amplitude-encoded calcium oscillations in fish cells. Biophys Chem 2011; 159:294-302. [PMID: 21908094 DOI: 10.1016/j.bpc.2011.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 08/09/2011] [Indexed: 01/29/2023]
Abstract
The reaction of intracellular Ca(2+) to different agonist stimuli in primary hepatocytes from rainbow trout (Oncorhynchus mykiss) as well as the permanent fish cell line RTL-W1 was investigated systematically. In addition to "classical" agonists such as phenylephrine and ATP, model environmental toxicants like 4-nitrophenol and 3,4-dichloroaniline were used to elucidate possible interactions between toxic effects and Ca(2+) signaling. We report Ca(2+) oscillations in response to several stimuli in RTL-W1 cells and to a lesser extent in primary hepatocytes. Moreover, these Ca(2+) oscillations are amplitude-encoded in contrast to their mammalian counterpart. Bioinformatics and computational analysis were employed to identify key players of Ca(2+) signaling in fish and to determine likely causes for the experimentally observed differences between the Ca(2+) dynamics in fish cells compared to those in mammalian liver cells.
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Affiliation(s)
- N Schweizer
- Aquatic Ecology and Toxicology Group, Center of Organismic Studies, University of Heidelberg, Im Neuenheimer Feld 504, D-69120 Heidelberg, Germany.
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Rüdiger S, Nagaiah C, Warnecke G, Shuai JW. Calcium domains around single and clustered IP3 receptors and their modulation by buffers. Biophys J 2010; 99:3-12. [PMID: 20655827 DOI: 10.1016/j.bpj.2010.02.059] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 02/12/2010] [Accepted: 02/26/2010] [Indexed: 02/04/2023] Open
Abstract
We study Ca(2+) release through single and clustered IP(3) receptor channels on the ER membrane under presence of buffer proteins. Our computational scheme couples reaction-diffusion equations and a Markovian channel model and allows our investigating the effects of buffer proteins on local calcium concentrations and channel gating. We find transient and stationary elevations of calcium concentrations around active channels and show how they determine release amplitude. Transient calcium domains occur after closing of isolated channels and constitute an important part of the channel's feedback. They cause repeated openings (bursts) and mediate increased release due to Ca(2+) buffering by immobile proteins. Stationary domains occur during prolonged activity of clustered channels, where the spatial proximity of IP(3)Rs produces a distinct [Ca(2+)] scale (0.5-10 microM), which is smaller than channel pore concentrations (>100 microM) but larger than transient levels. While immobile buffer affects transient levels only, mobile buffers in general reduce both transient and stationary domains, giving rise to Ca(2+) evacuation and biphasic modulation of release amplitude. Our findings explain recent experiments in oocytes and provide a general framework for the understanding of calcium signals.
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Affiliation(s)
- S Rüdiger
- Institute of Physics, Humboldt-Universität zu Berlin, Berlin, Germany
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Bodenstein C, Knoke B, Marhl M, Perc M, Schuster S. Using Jensen's inequality to explain the role of regular calcium oscillations in protein activation. Phys Biol 2010; 7:036009. [PMID: 20834115 DOI: 10.1088/1478-3975/7/3/036009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Oscillations of cytosolic Ca(2 +) are very important for cellular signalling in excitable and non-excitable cells. The information of various extracellular stimuli is encoded into oscillating patterns of Ca(2 +) that subsequently lead to the activation of different Ca(2 +)-sensitive target proteins in the cell. The question remains, however, why this information is transmitted by means of an oscillating rather than a constant signal. Here we show that, in fact, Ca(2 +) oscillations can achieve a better activation of target proteins than a comparable constant signal with the same amount of Ca(2 +) used. For this we use Jensen's inequality that describes the relation between the function value of the average of a set of argument values and the average of the function values of the arguments from that set. We analyse the role of the cooperativity of the binding of Ca(2 +) and of zero-order ultrasensitivity, which are two properties that are often observed in experiments on the activation of Ca(2 +)-sensitive target proteins. Our results apply to arbitrary oscillation shapes and a very general decoding model, thus generalizing the observations of several previous studies. We compare our results with data from experimental studies investigating the activation of nuclear factor of activated T cells (NFAT) and Ras by oscillatory and constant signals. Although we are restricted to specific approximations due to the lack of detailed kinetic data, we find good qualitative agreement with our theoretical predictions.
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Affiliation(s)
- C Bodenstein
- Department of Bioinformatics, Friedrich Schiller University Jena, Ernst-Abbe-Platz 2, D-07743 Jena, Germany.
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