1
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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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2
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Omagari D, Hayatsu M, Yamamoto K, Kobayashi M, Tsukano N, Nameta M, Mikami Y. Gap junction with MLO-A5 osteoblast-like cell line induces ALP and BSP transcription of 3T3-L1 pre-adipocyte like cell line via Hspb1 while retaining adipogenic differentiation ability. Bone 2020; 141:115596. [PMID: 32814124 DOI: 10.1016/j.bone.2020.115596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 08/09/2020] [Accepted: 08/10/2020] [Indexed: 12/09/2022]
Abstract
In bone tissues, gap junctions form direct links between the cytoplasm of an osteocyte and another adjacent osteocyte or osteoblast, which underlie both bone formation and bone resorption. We have previously demonstrated that alkaline phosphatase (ALP) and bone sialoprotein (BSP), which are osteoblast markers, were induced in mesenchymal stem cells (MSCs) co-cultured with osteoblast-like cell line. However, the molecular mechanism of this process has not been fully addressed. Furthermore, few advances have been made toward elucidating the communication networks that link the status of committed cells such as (pre-) adipocytes that differentiated from MSCs as well as osteoblasts. Therefore, the objective of the present study was to investigate the mechanism underlying the communication network between pre-adipocytes and osteoblasts. We evaluated the effect of co-culture with osteoblast on the cell status of pre-adipocytes using murine osteoblast-like cell line, MLO-A5, and pre-adipocyte-like cell line, 3T3-L1, respectively. The results presented here demonstrated that osteoblasts and pre-adipocytes communicate via gap junctions, and the ensuing drastic increase in ALP and BSP transcription in co-cultured pre-adipocytes was induced, at least partly, via heat shock protein family B member 1 (Hspb1). In addition, terminal differentiation into adipocytes was suppressed in pre-adipocytes during co-culture with osteoblast without loss of adipogenic differentiation ability. Interestingly, after co-culture with osteoblasts, isolated co-cultured pre-adipocytes were able to differentiate to adipocytes as well as original pre-adipocytes. These results suggest that gap junctional communication with osteoblasts suppressed adipogenic differentiation of pre-adipocytes without loss of adipogenic differentiation ability.
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Affiliation(s)
- Daisuke Omagari
- Department of Pathology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan
| | - Manabu Hayatsu
- Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata 951-8122, Japan
| | - Kiyofumi Yamamoto
- Department of Pharmacology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan
| | - Masayuki Kobayashi
- Department of Pharmacology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan
| | - Naruchika Tsukano
- Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata 951-8122, Japan
| | - Masaaki Nameta
- Electron Microscope Core Facility, Niigata University, 1-757 Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata 951-8122, Japan
| | - Yoshikazu Mikami
- Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata 951-8122, Japan.
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3
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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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4
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Zhou A, Liu X, Zhang S, Huo B. Effects of store-operated and receptor-operated calcium channels on synchronization of calcium oscillations in astrocytes. Biosystems 2020; 198:104233. [PMID: 32858094 DOI: 10.1016/j.biosystems.2020.104233] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/04/2020] [Accepted: 08/20/2020] [Indexed: 10/23/2022]
Abstract
Intercellular calcium signaling allows cells to communicate with each other and to interact with adjacent cells. Gap junction is the most common and important way for cellular communication. Recently, mathematical models have been widely used to gain a precise and quantitative understanding of the dynamics of intracellular calcium ions (Ca2+). In this paper, we establish a mathematical model considering the gap junction permeable to Ca2+ and to IP3 for describing the calcium oscillations in coupled astrocytes. Store-operated calcium entry (SOCE) is viewed as the main process which controls the non-excitable cells, hence, we focus on the effect of store-operated calcium channel (SOCC) and receptor-operated calcium channel (ROCC) on the intercellular synchronization, respectively. By employing bifurcation analysis on this model, the dynamic behaviors of the coupled system with different physiological state cells is obtained with changes in the maximum capacity of the SOCC and the ROCC. The synchronization boundaries for different conditions are gained in the two parameters space of the channel parameters and the coupling strength. The results suggest that the variation of the maximum flow for different calcium channels determines the stable oscillations of the coupled system, as well as for the frequency and amplitude of oscillations. The SOCC has an expected effect on the change of the oscillatory interval while the ROCC demonstrated the influence on the amplitude modulation. Furthermore, the coupling strength and channel parameters could induce 1:1 locking of intercellular Ca2+ oscillations and the synchronization region like Arnol'd tongue is found.
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Affiliation(s)
- Anqi Zhou
- Department of Mechanics, Tianjin University, Tianjin, 300354, PR China
| | - Xijun Liu
- Department of Mechanics, Tianjin University, Tianjin, 300354, PR China
| | - Suxia Zhang
- Department of Mechanics, Tianjin University, Tianjin, 300354, PR China.
| | - Bing Huo
- College of Mechanical Engineering, Tianjin University of Science & Technology, Tianjin, 300222, PR China
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5
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Limanjaya I, Hsu TI, Chuang JY, Kao TJ. L-selectin activation regulates Rho GTPase activity via Ca +2 influx in Sertoli cell line, ASC-17D cells. Biochem Biophys Res Commun 2020; 525:1011-1017. [PMID: 32178872 DOI: 10.1016/j.bbrc.2020.03.011] [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: 02/20/2020] [Accepted: 03/03/2020] [Indexed: 12/31/2022]
Abstract
In seminiferous epithelium, tight junctions (TJs) between adjacent Sertoli cells constitute the blood-testis barrier and must change synchronically for germ cells to translocate from the basal to the adluminal compartment during the spermatogenic cycle. Rho GTPase activation through stimulation with specific L-selectin ligands has been proposed to modulate tight junctional dynamics. However, little is known regarding the role of Ca+2 dynamics in Sertoli cell and how Ca+2 relays L-selectin signals to modulate Rho GTPase activity in Sertoli cells, thus prompting us to investigate the Ca+2 flux induced by L-selectin ligand in ASC-17D cells. Using fluorescent real-time image, we first demonstrated the increase of intracellular Ca+2 level following L-selectin ligand stimulation. This Ca+2 increase was inhibited in ASC-17D cells pretreated with nifedipine, the L-type voltage-operated Ca+2 channel (VOCC) blocker, but not mibefradil, the T-type VOCC blocker. We then demonstrated the up-regulation of Rho and Rac1 in ASC-17D cells following the administration of L-selectin ligand, and the pre-treatment with nifedipine, but not mibefradil, prior to L-selectin ligand-binding abolished the activation of both Rho and Rac1. Together, we conclude that the activation of L-selectin induces Ca+2 influx through the L-type VOCC, which up-regulates Rho and Rac1 proteins, in ASC-17D cells.
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Affiliation(s)
- Ivan Limanjaya
- College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Tsung-I Hsu
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei, Taiwan; Research Center of Neuroscience, Taipei Medical University, Taipei, Taiwan; TMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei, Taiwan
| | - Jian-Ying Chuang
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei, Taiwan; Research Center of Neuroscience, Taipei Medical University, Taipei, Taiwan; TMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei, Taiwan.
| | - Tzu-Jen Kao
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei, Taiwan; Research Center of Neuroscience, Taipei Medical University, Taipei, Taiwan; TMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei, Taiwan.
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6
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Eugenin EA, Valdebenito S, Gorska AM, Martínez AD, Bitran M, Sáez JC. Gap junctions coordinate the propagation of glycogenolysis induced by norepinephrine in the pineal gland. J Neurochem 2019; 151:558-569. [PMID: 31381153 DOI: 10.1111/jnc.14846] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 06/15/2019] [Accepted: 07/29/2019] [Indexed: 11/26/2022]
Abstract
Chemical and electrical synapses are the two major communication systems that permit cell-to-cell communication within the nervous system. Although most studies are focused on chemical synapses (glutamate, γ-aminobutyric acid, and other neurotransmitters), clearly both types of synapses interact and cooperate to allow the coordination of several cell functions within the nervous system. The pineal gland has limited independent axonal innervation and not every cell has access to nerve terminals. Thus, additional communication systems, such as gap junctions, have been postulated to coordinate metabolism and signaling. Using acutely isolated glands and dissociated cells, we found that gap junctions spread glycogenolytic signals from cells containing adrenoreceptors to the entire gland lacking these receptors. Our data using glycogen and lactate quantification, electrical stimulation, and high-performance liquid chromatography with electrochemical detection, demonstrate that gap junctional communication between cells of the rat pineal gland allows cell-to-cell propagation of norepinephrine-induced signal that promotes glycogenolysis throughout the entire gland. Thus, the interplay of both synapses is essential for coordinating glycogen metabolism and lactate production in the pineal gland.
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Affiliation(s)
| | | | | | - Agustin D Martínez
- Instituto de Neurociencias, Centro interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Marcela Bitran
- Departamento de Fisiologia, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Juan C Sáez
- Instituto de Neurociencias, Centro interdisciplinario de Neurociencias, Universidad de Valparaíso, Valparaíso, Chile.,Departamento de Fisiologia, Pontificia Universidad Catolica de Chile, Santiago, Chile
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7
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Ei Hsu Hlaing E, Ishihara Y, Wang Z, Odagaki N, Kamioka H. Role of intracellular Ca 2+-based mechanotransduction of human periodontal ligament fibroblasts. FASEB J 2019; 33:10409-10424. [PMID: 31238000 PMCID: PMC6704454 DOI: 10.1096/fj.201900484r] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Human periodontal ligament (hPDL) fibroblasts are thought to receive mechanical stress (MS) produced by orthodontic tooth movement, thereby regulating alveolar bone remodeling. However, the role of intracellular calcium ([Ca2+]i)-based mechanotransduction is not fully understood. We explored the MS-induced [Ca2+]i responses both in isolated hPDL fibroblasts and in intact hPDL tissue and investigated its possible role in alveolar bone remodeling. hPDL fibroblasts were obtained from healthy donors' premolars that had been extracted for orthodontic reasons. The oscillatory [Ca2+]i activity induced by static compressive force was measured by a live-cell Ca2+ imaging system and evaluated by several feature extraction method. The spatial pattern of cell-cell communication was investigated by Moran's I, an index of spatial autocorrelation and the gap junction (GJ) inhibitor. The Ca2+-transporting ionophore A23187 was used to further investigate the role of [Ca2+]i up-regulation in hPDL cell behavior. hPDL fibroblasts displayed autonomous [Ca2+]i responses. Compressive MS activated this autonomous responsive behavior with an increased percentage of responsive cells both in vitro and ex vivo. The integration, variance, maximum amplitude, waveform length, and index J in the [Ca2+]i responses were also significantly increased, whereas the mean power frequency was attenuated in response to MS. The increased Moran's I after MS indicated that MS might affect the pattern of cell-cell communication via GJs. Similar to the findings of MS-mediated regulation, the A23187-mediated [Ca2+]i uptake resulted in the up-regulation of receptor activator of NF-κB ligand (Rankl) and Sost along with increased sclerostin immunoreactivity, suggesting that [Ca2+]i signaling networks may be involved in bone remodeling. In addition, A23187-treated hPDL fibroblasts also showed the suppression of osteogenic differentiation and mineralization. Our findings suggest that augmented MS-mediated [Ca2+]i oscillations in hPDL fibroblasts enhance the production and release of bone regulatory signals via Rankl/Osteoprotegerin and the canonical Wnt/β-catenin pathway as an early process in tooth movement-initiated alveolar bone remodeling.-Ei Hsu Hlaing, E., Ishihara, Y., Wang, Z., Odagaki, N., Kamioka, H. Role of intracellular Ca2+-based mechanotransduction of human periodontal ligament fibroblasts.
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Affiliation(s)
- Ei Ei Hsu Hlaing
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan
| | | | - Ziyi Wang
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan.,Japan Society for the Promotion of Science (JSPS DC2), Tokyo, Japan
| | - Naoya Odagaki
- Department of Orthodontics, Okayama University Hospital, Okayama, Japan
| | - Hiroshi Kamioka
- Department of Orthodontics, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan
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8
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Verma A, Antony AN, Ogunnaike BA, Hoek JB, Vadigepalli R. Causality Analysis and Cell Network Modeling of Spatial Calcium Signaling Patterns in Liver Lobules. Front Physiol 2018; 9:1377. [PMID: 30337879 PMCID: PMC6180170 DOI: 10.3389/fphys.2018.01377] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 09/11/2018] [Indexed: 01/21/2023] Open
Abstract
Dynamics as well as localization of Ca2+ transients plays a vital role in liver function under homeostatic conditions, repair, and disease. In response to circulating hormonal stimuli, hepatocytes exhibit intracellular Ca2+ responses that propagate through liver lobules in a wave-like fashion. Although intracellular processes that control cell autonomous Ca2+ spiking behavior have been studied extensively, the intra- and inter-cellular signaling factors that regulate lobular scale spatial patterns and wave-like propagation of Ca2+ remain to be determined. To address this need, we acquired images of cytosolic Ca2+ transients in 1300 hepatocytes situated across several mouse liver lobules over a period of 1600 s. We analyzed this time series data using correlation network analysis, causal network analysis, and computational modeling, to characterize the spatial distribution of heterogeneity in intracellular Ca2+ signaling components as well as intercellular interactions that control lobular scale Ca2+ waves. Our causal network analysis revealed that hepatocytes are causally linked to multiple other co-localized hepatocytes, but these influences are not necessarily aligned uni-directionally along the sinusoids. Our computational model-based analysis showed that spatial gradients of intracellular Ca2+ signaling components as well as intercellular molecular exchange are required for lobular scale propagation of Ca2+ waves. Additionally, our analysis suggested that causal influences of hepatocytes on Ca2+ responses of multiple neighbors lead to robustness of Ca2+ wave propagation through liver lobules.
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Affiliation(s)
- Aalap Verma
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States.,Department of Pathology, Anatomy and Cell Biology, Daniel Baugh Institute for Functional Genomics and Computational Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Anil Noronha Antony
- Department of Pathology, Anatomy and Cell Biology, Daniel Baugh Institute for Functional Genomics and Computational Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Babatunde A Ogunnaike
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, United States
| | - Jan B Hoek
- Department of Pathology, Anatomy and Cell Biology, Daniel Baugh Institute for Functional Genomics and Computational Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Rajanikanth Vadigepalli
- Department of Pathology, Anatomy and Cell Biology, Daniel Baugh Institute for Functional Genomics and Computational Biology, Thomas Jefferson University, Philadelphia, PA, United States
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9
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Brodsky VY. Biochemistry of Direct Cell−Cell Interactions. Signaling Factors Regulating Orchestration of Cell Populations. BIOCHEMISTRY (MOSCOW) 2018; 83:890-906. [DOI: 10.1134/s0006297918080035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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10
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Trampert DC, Nathanson MH. Regulation of bile secretion by calcium signaling in health and disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2018; 1865:1761-1770. [PMID: 29787781 DOI: 10.1016/j.bbamcr.2018.05.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 05/12/2018] [Accepted: 05/16/2018] [Indexed: 12/15/2022]
Abstract
Calcium (Ca2+) signaling controls secretion in many types of cells and tissues. In the liver, Ca2+ regulates secretion in both hepatocytes, which are responsible for primary formation of bile, and cholangiocytes, which line the biliary tree and further condition the bile before it is secreted. Cholestatic liver diseases, which are characterized by impaired bile secretion, may result from impaired Ca2+ signaling mechanisms in either hepatocytes or cholangiocytes. This review will discuss the Ca2+ signaling machinery and mechanisms responsible for regulation of secretion in both hepatocytes and cholangiocytes, and the pathophysiological changes in Ca2+ signaling that can occur in each of these cell types to result in cholestasis.
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Affiliation(s)
- David C Trampert
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520-8019, USA
| | - Michael H Nathanson
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520-8019, USA.
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11
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Verma A, Makadia H, Hoek JB, Ogunnaike BA, Vadigepalli R. Computational Modeling of Spatiotemporal Ca(2+) Signal Propagation Along Hepatocyte Cords. IEEE Trans Biomed Eng 2016; 63:2047-55. [PMID: 27076052 DOI: 10.1109/tbme.2016.2550045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
OBJECTIVE The purpose of this study is to model the dynamics of lobular Ca(2+) wave propagation induced by an extracellular stimulus, and to analyze the effect of spatially systematic variations in cell-intrinsic signaling parameters on sinusoidal Ca(2+) response. METHODS We developed a computational model of lobular scale Ca(2+) signaling that accounts for receptor- mediated initiation of cell-intrinsic Ca(2+) signal in hepatocytes and its propagation to neighboring hepatocytes through gap junction-mediated molecular exchange. RESULTS Analysis of the simulations showed that a pericentral-to-periportal spatial gradient in hormone sensitivity and/or rates of IP3 synthesis underlies the Ca(2+) wave propagation. We simulated specific cases corresponding to localized disruptions in the graded pattern of these parameters along a hepatic sinusoid. Simulations incorporating locally altered parameters exhibited Ca(2+) waves that do not propagate throughout the hepatic plate. Increased gap junction coupling restored normal Ca(2+) wave propagation when hepatocytes with low Ca(2+) signaling ability were localized in the midlobular or the pericentral region. CONCLUSION Multiple spatial patterns in intracellular signaling parameters can lead to Ca(2+) wave propagation that is consistent with the experimentally observed spatial patterns of Ca(2+) dynamics. Based on simulations and analysis, we predict that increased gap junction-mediated intercellular coupling can induce robust Ca(2+) signals in otherwise poorly responsive hepatocytes, at least partly restoring the sinusoidally oriented Ca (2+) waves. SIGNIFICANCE Our bottom-up model of agonist-evoked spatial Ca(2+) patterns can be integrated with detailed descriptions of liver histology to study Ca(2+) regulation at the tissue level.
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12
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Lembong J, Sabass B, Sun B, Rogers ME, Stone HA. Mechanics regulates ATP-stimulated collective calcium response in fibroblast cells. J R Soc Interface 2016; 12:20150140. [PMID: 26063818 DOI: 10.1098/rsif.2015.0140] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Cells constantly sense their chemical and mechanical environments. We study the effect of mechanics on the ATP-induced collective calcium response of fibroblast cells in experiments that mimic various tissue environments. We find that closely packed two-dimensional cell cultures on a soft polyacrylamide gel (Young's modulus E = 690 Pa) contain more cells exhibiting calcium oscillations than cultures on a rigid substrate (E = 36 000 Pa). Calcium responses of cells on soft substrates show a slower decay of calcium level relative to those on rigid substrates. Actin enhancement and disruption experiments for the cell cultures allow us to conclude that actin filaments determine the collective Ca(2+) oscillatory behaviour in the culture. Inhibition of gap junctions results in a decrease of the oscillation period and reduced correlation of calcium responses, which suggests additional complexity of signalling upon cell-cell contact. Moreover, the frequency of calcium oscillations is independent of the rigidity of the substrate but depends on ATP concentration. We compare our results with those from similar experiments on individual cells. Overall, our observations show that collective chemical signalling in cell cultures via calcium depends critically on the mechanical environment.
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Affiliation(s)
- Josephine Lembong
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA
| | - Benedikt Sabass
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, USA
| | - Bo Sun
- Department of Physics, Oregon State University, Corvallis, OR, USA
| | | | - Howard A Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, USA
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13
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Mikami Y, Yamamoto K, Akiyama Y, Kobayashi M, Watanabe E, Watanabe N, Asano M, Shimizu N, Komiyama K. Osteogenic gene transcription is regulated via gap junction-mediated cell-cell communication. Stem Cells Dev 2015; 24:214-27. [PMID: 25137151 DOI: 10.1089/scd.2014.0060] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
An analytical study of cell-cell communications between murine osteoblast-like MLO-A5 cells and bone marrow mesenchymal stem cell (BMSC)-like C3H10T1/2 cells was performed. C3H10T1/2 cells expressing green fluorescent protein (10T-GFP cells) were generated to enable the isolation of the BMSC-like cells from co-cultures with MLO-A5 cells. The mRNA expression levels of several osteogenic transcription factors (Runx2, Osterix, Dlx5, and Msx2) did not differ between the co-cultured and mono-cultured 10T-GFP cells, but those of alkaline phosphatase (ALP) and bone sialoprotein (BSP) were 300- to 400-fold higher in the co-cultured cells. Patch clamp and biocytin transfer assays revealed gap junction-mediated communication between co-cultured 10T-GFP and MLO-A5 cells. The addition of a gap junction inhibitor suppressed the increases in the expression levels of the ALP and BSP mRNAs in co-cultured 10T-GFP cells. Furthermore, the histone acetylation levels were higher in co-cultured 10T-GFP cells than in mono-cultured 10T-GFP cells. These results suggest that osteoblasts and BMSCs associate via gap junctions, and that gap junction-mediated signaling induces histone acetylation that leads to elevated transcription of the genes encoding ALP and BSP in BMSCs.
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Affiliation(s)
- Yoshikazu Mikami
- 1 Department of Pathology, Nihon University School of Dentistry , Tokyo, Japan
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14
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Kim D, Seo Y, Kwon S. Role of gap junction communication in hepatocyte/fibroblast co-cultures: Implications for hepatic tissue engineering. BIOTECHNOL BIOPROC E 2015. [DOI: 10.1007/s12257-014-0595-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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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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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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Sphingosine kinase-1 inhibition protects primary rat hepatocytes against bile salt-induced apoptosis. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1922-9. [PMID: 23816565 DOI: 10.1016/j.bbadis.2013.06.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 05/10/2013] [Accepted: 06/19/2013] [Indexed: 01/22/2023]
Abstract
Sphingosine kinases (SphKs) and their product sphingosine-1-phosphate (S1P) have been reported to regulate apoptosis and survival of liver cells. Cholestatic liver diseases are characterized by cytotoxic levels of bile salts inducing liver injury. It is unknown whether SphKs and/or S1P play a role in this pathogenic process. Here, we investigated the putative involvement of SphK1 and S1P in bile salt-induced cell death in hepatocytes. Primary rat hepatocytes were exposed to glycochenodeoxycholic acid (GCDCA) to induce apoptosis. GCDCA-exposed hepatocytes were co-treated with S1P, the SphK1 inhibitor Ski-II and/or specific antagonists of S1P receptors (S1PR1 and S1PR2). Apoptosis and necrosis were quantified. Ski-II significantly reduced GCDCA-induced apoptosis in hepatocytes (-70%, P<0.05) without inducing necrosis. GCDCA increased the S1P levels in hepatocytes (P<0.05). GCDCA induced [Ca(2+)] oscillations in hepatocytes and co-treatment with the [Ca(2+)] chelator BAPTA repressed GCDCA-induced apoptosis. Ski-II inhibited the GCDCA-induced intracellular [Ca(2+)] oscillations. Transcripts of all five S1P receptors were detected in hepatocytes, of which S1PR1 and S1PR2 appear most dominant. Inhibition of S1PR1, but not S1PR2, reduced GCDCA-induced apoptosis by 20%. Exogenous S1P also significantly reduced GCDCA-induced apoptosis (-50%, P<0.05), however, in contrast to the GCDCA-induced (intracellular) SphK1 pathway, this was dependent on S1PR2 and not S1PR1. Our results indicate that SphK1 plays a pivotal role in mediating bile salt-induced apoptosis in hepatocytes in part by interfering with intracellular [Ca(2+)] signaling and activation of S1PR1.
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Abstract
Intercellular calcium (Ca(2+)) waves (ICWs) represent the propagation of increases in intracellular Ca(2+) through a syncytium of cells and appear to be a fundamental mechanism for coordinating multicellular responses. ICWs occur in a wide diversity of cells and have been extensively studied in vitro. More recent studies focus on ICWs in vivo. ICWs are triggered by a variety of stimuli and involve the release of Ca(2+) from internal stores. The propagation of ICWs predominately involves cell communication with internal messengers moving via gap junctions or extracellular messengers mediating paracrine signaling. ICWs appear to be important in both normal physiology as well as pathophysiological processes in a variety of organs and tissues including brain, liver, retina, cochlea, and vascular tissue. We review here the mechanisms of initiation and propagation of ICWs, the key intra- and extracellular messengers (inositol 1,4,5-trisphosphate and ATP) mediating ICWs, and the proposed physiological functions of ICWs.
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Affiliation(s)
- Luc Leybaert
- Department of Basic Medical Sciences, Physiology Group, Faculty of Medicine & Health Sciences, Ghent University, Ghent, Belgium.
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19
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Abstract
After partial hepatectomy (PH) the initial mass of the organ is restored through a complex network of cellular interactions that orchestrate both proliferative and hepatoprotective signalling cascades. Among agonists involved in this network many of them drive Ca(2+) movements. During liver regeneration in the rat, hepatocyte cytosolic Ca(2+) signalling has been shown on the one hand to be deeply remodelled and on the other hand to enhance progression of hepatocytes through the cell cycle. Mechanisms through which cytosolic Ca(2+) signals impact on hepatocyte cell cycle early after PH are not completely understood, but at least they include regulation of immediate early gene transcription and ERK and CREB phosphorylation. In addition to cytosolic Ca(2+), there is also evidence that mitochondrial Ca(2+) and also nuclear Ca(2+) may be critical for the regulation of liver regeneration. Finally, Ca(2+) movements in hepatocytes, and possibly in other liver cells, not only impact hepatocyte progression in the cell cycle but more generally may regulate cellular homeostasis after PH.
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20
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Combettes L, Dupont G. [Experimental and computational approach of calcium signaling]. Med Sci (Paris) 2011; 27:170-6. [PMID: 21382325 DOI: 10.1051/medsci/2011272170] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In many cell types, specific and robust signalling relies on a high level of spatiotemporal organization of Ca(2+) dynamics. In response to external stimulation, Ca(2+) signals ranging from a small increase of a few tens of nanomolar concentrations at the mouth of an inositol 1, 4, 5-trisphosphate receptor to the periodic propagation of waves invading an organ or a tissue, can be observed. Here, we review our combined experimental and computational approach of Ca(2+) dynamics, which has been mainly carried out on liver hepatocytes. We focus in particular on the understanding of the relationship between elementary Ca(2+) increases, Ca(2+) oscillations and intra- or intercellular Ca(2+) waves. The physiological impact of such signalling on liver function is also discussed.
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Shi JC, Dong T, Huang CS. The synchronization of calcium oscillations in coupled hepatocytes: The mean field coupling. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.06.083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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22
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Kang M, Othmer HG. Spatiotemporal characteristics of calcium dynamics in astrocytes. CHAOS (WOODBURY, N.Y.) 2009; 19:037116. [PMID: 19792041 PMCID: PMC2852438 DOI: 10.1063/1.3206698] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2009] [Accepted: 07/24/2009] [Indexed: 05/28/2023]
Abstract
Although Ca(i)(2+) waves in networks of astrocytes in vivo are well documented, propagation in vivo is much more complex than in culture, and there is no consensus concerning the dominant roles of intercellular and extracellular messengers [inositol 1,4,5-trisphosphate (IP(3)) and adenosine-5'-triphosphate (ATP)] that mediate Ca(i)(2+) waves. Moreover, to date only simplified models that take very little account of the geometrical struture of the networks have been studied. Our aim in this paper is to develop a mathematical model based on realistic cellular morphology and network connectivity, and a computational framework for simulating the model, in order to address these issues. In the model, Ca(i) (2+) wave propagation through a network of astrocytes is driven by IP(3) diffusion between cells and ATP transport in the extracellular space. Numerical simulations of the model show that different kinetic and geometric assumptions give rise to differences in Ca(i)(2+) wave propagation patterns, as characterized by the velocity, propagation distance, time delay in propagation from one cell to another, and the evolution of Ca(2+) response patterns. The temporal Ca(i)(2+) response patterns in cells are different from one cell to another, and the Ca(i)(2+) response patterns evolve from one type to another as a Ca(i)(2+) wave propagates. In addition, the spatial patterns of Ca(i)(2+) wave propagation depend on whether IP(3), ATP, or both are mediating messengers. Finally, two different geometries that reflect the in vivo and in vitro configuration of astrocytic networks also yield distinct intracellular and extracellular kinetic patterns. The simulation results as well as the linear stability analysis of the model lead to the conclusion that Ca(i)(2+) waves in astrocyte networks are probably mediated by both intercellular IP(3) transport and nonregenerative (only the glutamate-stimulated cell releases ATP) or partially regenerative extracellular ATP signaling.
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Affiliation(s)
- Minchul Kang
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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23
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Dupont G, Combettes L. What can we learn from the irregularity of Ca2+ oscillations? CHAOS (WOODBURY, N.Y.) 2009; 19:037112. [PMID: 19792037 DOI: 10.1063/1.3160569] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In most cells, Ca(2+) increases in response to external stimulation are organized in the form of oscillations and waves that sometimes propagate from one cell to another. Numerous experimental and theoretical studies reveal that this spatiotemporal organization contains a non-negligible level of stochasticity. In this study, we extend the previous work based on a statistical analysis of experimental Ca(2+) traces in isolated, hormone-stimulated hepatocytes and on stochastic simulations of Ca(2+) oscillations based on the Gillespie's algorithm. Comparison of the coefficients of variation in the periods of experimental and simulated Ca(2+) spikes provides information about the clustering and the specific subtypes of the Ca(2+) channels. In hepatocytes coupled by gap junctions, the global perfusion with a hormone leads to successive Ca(2+) responses, giving the appearance of an intercellular wave. Statistical analysis of experimental Ca(2+) oscillations in coupled hepatocytes confirms that this coordinated Ca(2+) spiking corresponds to a phase wave but suggests the existence of an additional coupling mechanism.
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Affiliation(s)
- Geneviève Dupont
- Unité de Chronobiologie Théorique, Faculté des Sciences, Université Libre de Bruxelles, Brussels, Belgium
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24
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Brodsky VY. Direct cell-cell communications and social behavior of cells in mammals, protists, and bacteria. Possible causes of multicellularity. Russ J Dev Biol 2009. [DOI: 10.1134/s1062360409020027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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25
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Gosak M. Cellular diversity promotes intercellular Ca2+ wave propagation. Biophys Chem 2009; 139:53-6. [DOI: 10.1016/j.bpc.2008.10.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 10/09/2008] [Accepted: 10/10/2008] [Indexed: 10/21/2022]
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26
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Dernison M, Kusters J, Peters P, van Meerwijk W, Ypey D, Gielen C, van Zoelen E, Theuvenet A. Local induction of pacemaking activity in a monolayer of electrically coupled quiescent NRK fibroblasts. Cell Calcium 2008; 44:429-40. [DOI: 10.1016/j.ceca.2008.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Revised: 12/22/2007] [Accepted: 02/11/2008] [Indexed: 11/30/2022]
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27
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The manipulation of calcium oscillations by harnessing self-organisation. Biosystems 2008; 94:153-63. [PMID: 18606209 DOI: 10.1016/j.biosystems.2008.05.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Revised: 10/29/2007] [Accepted: 05/23/2008] [Indexed: 11/21/2022]
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28
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Jones BF, Boyles RR, Hwang SY, Bird GS, Putney JW. Calcium influx mechanisms underlying calcium oscillations in rat hepatocytes. Hepatology 2008; 48:1273-81. [PMID: 18802964 PMCID: PMC2808042 DOI: 10.1002/hep.22461] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
UNLABELLED The process of capacitative or store-operated Ca(2+) entry has been extensively investigated, and recently two major molecular players in this process have been described. Stromal interacting molecule (STIM) 1 acts as a sensor for the level of Ca(2+) stored in the endoplasmic reticulum, and Orai proteins constitute pore-forming subunits of the store-operated channels. Store-operated Ca(2+) entry is readily demonstrated with protocols that provide extensive Ca(2+) store depletion; however, the role of store-operated entry with modest and more physiological cell stimuli is less certain. Recent studies have addressed this question in cell lines; however, the role of store-operated entry during physiological activation of primary cells has not been extensively investigated, and there is little or no information on the roles of STIM and Orai proteins in primary cells. Also, the nature of the Ca(2+) influx mechanism with hormone activation of hepatocytes is controversial. Hepatocytes respond to physiological levels of glycogenolytic hormones with well-characterized intracellular Ca(2+) oscillations. In the current study, we have used both pharmacological tools and RNA interference (RNAi)-based techniques to investigate the role of store-operated channels in the maintenance of hormone-induced Ca(2+) oscillations in rat hepatocytes. Pharmacological inhibitors of store-operated channels blocked thapsigargin-induced Ca(2+) entry but only partially reduced the frequency of Ca(2+) oscillations. Similarly, RNAi knockdown of STIM1 or Orai1 substantially reduced thapsigargin-induced calcium entry, and more modestly diminished the frequency of vasopressin-induced oscillations. CONCLUSION Our findings establish that store-operated Ca(2+) entry plays a role in the maintenance of agonist-induced oscillations in primary rat hepatocytes but indicate that other agonist-induced entry mechanisms must be involved to a significant extent.
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Affiliation(s)
- Bertina F Jones
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences-NIH, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
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29
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Advantages and limitations of commonly used methods to assay the molecular permeability of gap junctional intercellular communication. Biotechniques 2008; 45:33-52, 56-62. [PMID: 18611167 DOI: 10.2144/000112810] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The role of gap junctional intercellular communication (GJIC) in regulation of normal growth and differentiation is becoming increasingly recognized as a major cellular function. GJIC consists of intercellular exchange of low molecular weight molecules, and is the only means for direct contact between cytoplasms of adjacent animal cells. Disturbances of GJIC have been associated with many pathological conditions, such as carcinogenesis or hereditary illness. Reliable and accurate methods for the determination of GJIC are therefore important in cell biology studies. There are several methods used successfully in numerous laboratories to measure GJIC both in vitro and in vivo. This review comments on techniques currently used to study cell-to-cell communication, either by measuring dye transfer, as in methods like microinjection, scrape loading, gap-fluorescence recovery after photobleaching (gap-FRAP), the preloading assay, and local activation of a molecular fluorescent probe (LAMP), or by measuring electrical conductance and metabolic cooperation. As we will discuss in this review, these techniques are not equivalent but instead provide complementary information. We will focus on their main advantages and limitations. Although biological applications guide the choice of techniques we describe, we also review points that must be taken into consideration before using a methodology, such as the number of cells to analyze.
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31
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Kepseu WD, Woafo P. Long-range interaction effects on calcium-wave propagation. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:011922. [PMID: 18763997 DOI: 10.1103/physreve.78.011922] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 04/30/2008] [Indexed: 05/26/2023]
Abstract
In this paper, numerical simulation of calcium waves in a network of cells coupled together by a paracrine signaling is investigated. The model takes into account the long-range interaction between cells due to the action of extracellular messengers, which provide links between first-neighbor cells, but also on cells located far away from the excited cell. When considering bidirectional coupling, the long-range interaction influences neither the frequency nor the amplitude of oscillations, contrary to one-directional coupling. The long-range interaction influences the speed of propagation of Ca2+ waves in the network and induces enlargement of the transition zone before the steady regime of propagation is attained. We also investigate the long-range effects on the colonization of a given niche by a pathogenic microorganism signal on calcium wave propagation in the network.
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Affiliation(s)
- W D Kepseu
- Laboratory of Modeling and Simulation in Engineering and Biological Physics, Faculty of Science, University of Yaounde I, PO Box 812, Yaounde, Cameroon
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32
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Gaspers LD, Thomas AP. Calcium signaling in liver. Cell Calcium 2008; 38:329-42. [PMID: 16139354 DOI: 10.1016/j.ceca.2005.06.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 06/28/2005] [Indexed: 10/25/2022]
Abstract
In hepatocytes, hormones linked to the formation of the second messenger inositol 1,4,5-trisphosphate (InsP3) evoke transient increases or spikes in cytosolic free calcium ([Ca2+]i), that increase in frequency with the agonist concentration. These oscillatory Ca2+ signals are thought to transmit the information encoded in the extracellular stimulus to down-stream Ca2+-sensitive metabolic processes. We have utilized both confocal and wide field fluorescence microscopy techniques to study the InsP3-dependent signaling pathway at the cellular and subcellular levels in the intact perfused liver. Typically InsP3-dependent [Ca2+]i spikes manifest as Ca2+ waves that propagate throughout the entire cytoplasm and nucleus, and in the intact liver these [Ca2+]i increases are conveyed through gap junctions to encompass entire lobular units. The translobular movement of Ca2+ provides a means to coordinate the function of metabolic zones of the lobule and thus, liver function. In this article, we describe the characteristics of agonist-evoked [Ca2+]i signals in the liver and discuss possible mechanisms to explain the propagation of intercellular Ca2+ waves in the intact organ.
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Affiliation(s)
- Lawrence D Gaspers
- Department of Pharmacology and Physiology, New Jersey Medical School of University of Medicine and Dentistry of New Jersey, Medical Science Building, H609, 185 South Orange Avenue, P.O. Box 1709, Newark, NJ 07103-1709, USA
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33
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Shabir S, Southgate J. Calcium signalling in wound-responsive normal human urothelial cell monolayers. Cell Calcium 2008; 44:453-64. [PMID: 18417211 DOI: 10.1016/j.ceca.2008.02.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Revised: 02/21/2008] [Accepted: 02/28/2008] [Indexed: 11/15/2022]
Abstract
Epithelial tissue repair requires coordination of migratory and proliferative activity both adjacent to and remote from the wound edge. Although calcium signalling is implicated, the specific mechanisms are poorly understood. This study characterises the calcium signal invoked in response to scratch wounding of normal human urothelial (NHU) cells and relates it to the localised cellular response. Immediately after wounding of confluent NHU cell monolayers, cells adjacent to the wound edge showed a sustained (>30 min) rise in [Ca(2+)](i), while there was an independent, but simultaneous calcium wave that propagated out from the wound edge. The transient signal involved release of calcium from intracellular stores and was not mediated via gap junctions, but by diffusion of extracellular agonists. We demonstrated that ATP was partially responsible for the initiation and propagation of the calcium wave and showed that the calcium release mechanism was mediated in part via activation of inositol-1,4,5-triphosphate (IP(3)) receptors. By contrast, the sustained calcium signal originated from the extracellular milieu and correlated with an increased rate of migration by these cells. The work presented here provides supportive evidence that the calcium signature, defined by its temporal and amplitude characteristics, is important in co-ordinating the response of cells within an epithelial cell monolayer after wounding.
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Affiliation(s)
- Saqib Shabir
- Jack Birch Unit of Molecular Carcinogenesis, Department of Biology, University of York YO10 5YW, UK
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34
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Affiliation(s)
- Andrew L Harris
- Department of Pharmacology and Physiology, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA.
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35
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Sibaev A, Yüce B, Schirra J, Göke B, Allescher HD, Storr M. Are gap junctions truly involved in inhibitory neuromuscular interaction in mouse proximal colon? Clin Exp Pharmacol Physiol 2007; 33:740-5. [PMID: 16895549 DOI: 10.1111/j.1440-1681.2006.04433.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. Gap junctions exist between circular muscle cells of the colon and between interstitial cells of Cajal (ICC) in the myenteric plexus of the gastrointestinal tract. They also probably couple intramuscular ICC with smooth muscle cells. Recent functional evidence for this was found in dye-coupling and myoelectrical experiments. 2. In the present study, we tested the hypothesis of gap junctions putatively being involved in neuromuscular interaction in mouse colon by using different classes of gap junction blockers. 3. Electrical field stimulation of the myenteric plexus elicited tetrodotoxin-sensitive and hexamethonium-independent fast and slow inhibitory junction potentials (fIJP and sIJP, respectively) in circular smooth muscle cells, as evaluated by intracellular recording techniques in impaled smooth muscle cells. Heptanol produced a time-dependent hyperpolarization of the membrane potential (MP) and abolished fIJP and sIJP. Octanol had no effect on the MP and abolished fIJP and sIJP. Carbenoxolone produced a time-dependent depolarization of the MP without any effect on fIJP or sIJP. The connexin 43 mimetic gap junction blocker GAP-27 had no effect on MP, fIJP or sIJP. 4. Based on the presently available gap junction blockers we found no evidence that gap junctions are involved in neuromuscular transmission in mouse colon, as suggested by morphological studies.
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Affiliation(s)
- Andrei Sibaev
- Department of Internal Medicine II, Ludwig Maximilians University Munich, Munich, Germany
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36
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Serrière V, Tran D, Stelly N, Claret M, Alonso G, Tordjmann T, Guillon G. Vasopressin-induced morphological changes in polarized rat hepatocyte multiplets: dual calcium-dependent effects. Cell Calcium 2007; 43:95-104. [PMID: 17555812 DOI: 10.1016/j.ceca.2007.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 04/03/2007] [Accepted: 04/10/2007] [Indexed: 11/26/2022]
Abstract
Calcium-mobilizing hormones and neurotransmitters are known to affect cell morphology and function including cell differentiation or division. In this study, we examined vasopressin (AVP)-induced morphological changes in a polarized system of rat hepatocytes. Light and electron microscope observations showed that AVP induced microvilli formation and a remodeling of the isolated hepatocyte F-actin submembrane cytoskeleton, these two events being correlated. We showed that these effects were rapid, reversible, observed at nanomolar AVP concentration and mediated by the V(1a) receptor. On polarized multicellular systems of hepatocytes, we observed a rapid reduction of the bile canaliculi lumen at the apical pole and micovilli formation at the basolateral domain with an enlarged F-actin cytoskeleton. Neither activation of protein kinase C nor A via phorbol ester or dibutyryl cAMP induced such rapid morphological changes, at variance with ionomycin, suggesting that AVP-induced intracellular calcium rise plays a crucial role in those effects. By using spectrofluorimetry and cytochemistry, we showed that calcium release from intracellular stores was involved in bile canaliculus contraction, while calcium entry from the extracellular space controlled microvilli formation. Taken together, AVP and calcium-mobilizing agonists differentially regulate physiological hepatocyte plasma membrane events at the basal and the apical domains via topographically specialized calcium-dependent mechanisms.
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Affiliation(s)
- Valérie Serrière
- INSERM, U.757, Université Paris-Sud, Bât. 443, 91405 Orsay Cedex, France
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37
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Li Q, Wang Y. Coupling and internal noise sustain synchronized oscillation in calcium system. Biophys Chem 2007; 129:23-8. [PMID: 17537568 DOI: 10.1016/j.bpc.2007.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 05/01/2007] [Accepted: 05/01/2007] [Indexed: 10/23/2022]
Abstract
In this work, the effects of coupling on two calcium subsystems were investigated, the cooperation between coupling and internal noise was also considered. When two non-identical subsystems are in steady state, coupling can induce oscillations, and distinctly enlarge the oscillatory region in bifurcation diagram. Besides, coupling can make the two non-identical oscillators synchronized. With the increment of the coupling strength, the cross-correlation time of the two oscillators firstly increases and then decreases to be constant, showing the synchronization without tuning coupling strength. When internal noise is considered, similar phenomena can also be obtained under the cooperation between coupling and internal noise.
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Affiliation(s)
- Qianshu Li
- The Institute for Chemical Physics, Beijing Institute of Technology, Beijing, 100081, PR China.
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38
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Harris AL. Connexin channel permeability to cytoplasmic molecules. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2007; 94:120-43. [PMID: 17470375 PMCID: PMC1995164 DOI: 10.1016/j.pbiomolbio.2007.03.011] [Citation(s) in RCA: 357] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Connexin channels are known to be permeable to a variety of cytoplasmic molecules. The first observation of second messenger junctional permeability, made approximately 30 years ago, sparked broad interest in gap junction channels as mediators of intercellular molecular signaling. Since then, much has been learned about the diversity of connexin channels with regard to isoform diversity, tissue and developmental distribution, modes of channel regulation, assembly, expression, biochemical modification and permeability, all of which appear to be dynamically regulated. This information has expanded the potential roles of connexin channels in development, physiology and disease, and made their elucidation much more complex--30 years ago such an orchestra of junctional dynamics was unanticipated. Only recently, however, have investigators been able to directly address, in this more complex framework, the key issue: what specific biological molecules, second messengers and others, are able to permeate the various types of connexin channels, and how well? An important related issue, given the ever-growing list of connexin-related pathologies, is how these permeabilities are altered by disease-causing connexin mutations. Together, many studies show that a variety of cytoplasmic molecules can permeate the different types of connexin channels. A few studies reveal differences in permeation by different molecules through a particular type of connexin channel, and differences in permeation by a particular molecule through different types of connexin channels. This article describes and evaluates the various methods used to obtain these data, presents an annotated compilation of the results, and discusses the findings in the context of what can be inferred about mechanism of selectivity and potential relevance to signaling. The data strongly suggest that highly specific interactions take place between connexin pores and specific biological molecular permeants, and that those interactions determine which cytoplasmic molecules can permeate and how well. At this time, the nature of those interactions is unclear. One hopes that with more detailed permeability and structural information, the specific molecular mechanisms of the selectivity can be elucidated.
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Affiliation(s)
- Andrew L Harris
- Department of Pharmacology and Physiology, New Jersey Medical School of UMDNJ, Newark, NJ 07103, USA.
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Hernandez E, Leite MF, Guerra MT, Kruglov EA, Bruna-Romero O, Rodrigues MA, Gomes DA, Giordano FJ, Dranoff JA, Nathanson MH. The spatial distribution of inositol 1,4,5-trisphosphate receptor isoforms shapes Ca2+ waves. J Biol Chem 2007; 282:10057-10067. [PMID: 17284437 PMCID: PMC2825872 DOI: 10.1074/jbc.m700746200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Cytosolic Ca(2+) is a versatile second messenger that can regulate multiple cellular processes simultaneously. This is accomplished in part through Ca(2+) waves and other spatial patterns of Ca(2+) signals. To investigate the mechanism responsible for the formation of Ca(2+) waves, we examined the role of inositol 1,4,5-trisphosphate receptor (InsP3R) isoforms in Ca(2+) wave formation. Ca(2+) signals were examined in hepatocytes, which express the type I and II InsP3R in a polarized fashion, and in AR4-2J cells, a nonpolarized cell line that expresses type I and II InsP3R in a ratio similar to what is found in hepatocytes but homogeneously throughout the cell. Expression of type I or II InsP3R was selectively suppressed by isoform-specific DNA antisense in an adenoviral delivery system, which was delivered to AR4-2J cells in culture and to hepatocytes in vivo. Loss of either isoform inhibited Ca(2+) signals to a similar extent in AR4-2J cells. In contrast, loss of the basolateral type I InsP3R decreased the sensitivity of hepatocytes to vasopressin but had little effect on the initiation or spread of Ca(2+) waves across hepatocytes. Loss of the apical type II isoform caused an even greater decrease in the sensitivity of hepatocytes to vasopressin and resulted in Ca(2+) waves that were much slower and delayed in onset. These findings provide evidence that the apical concentration of type II InsP3Rs is essential for the formation of Ca(2+) waves in hepatocytes. The subcellular distribution of InsP3R isoforms may critically determine the repertoire of spatial patterns of Ca(2+) signals.
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MESH Headings
- Animals
- Base Sequence
- Calcium Channels/chemistry
- Calcium Channels/genetics
- Calcium Channels/physiology
- Calcium Signaling/physiology
- Cells, Cultured
- Hepatocytes/metabolism
- Inositol 1,4,5-Trisphosphate Receptors/chemistry
- Inositol 1,4,5-Trisphosphate Receptors/genetics
- Inositol 1,4,5-Trisphosphate Receptors/physiology
- Membrane Glycoproteins/chemistry
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/physiology
- Molecular Sequence Data
- Protein Isoforms/chemistry
- Protein Isoforms/physiology
- Rats
- Receptors, Cytoplasmic and Nuclear/chemistry
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/physiology
- Vasopressins/physiology
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Affiliation(s)
- Erick Hernandez
- Department of Pediatrics, Yale University, New Haven, Connecticut 06520
| | - M Fatima Leite
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Mateus T Guerra
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Emma A Kruglov
- Department of Medicine, Yale University, New Haven, Connecticut 06520
| | - Oscar Bruna-Romero
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Michele A Rodrigues
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil; Department of Medicine, Yale University, New Haven, Connecticut 06520
| | - Dawidson A Gomes
- Department of Medicine, Yale University, New Haven, Connecticut 06520
| | - Frank J Giordano
- Department of Medicine, Yale University, New Haven, Connecticut 06520
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40
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Chen H, Zhang J, Liu J. Selective effects of external noise on Ca2+ signal in mesoscopic scale biochemical cell systems. Biophys Chem 2007; 125:397-402. [PMID: 17069960 DOI: 10.1016/j.bpc.2006.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2006] [Revised: 10/03/2006] [Accepted: 10/03/2006] [Indexed: 11/30/2022]
Abstract
We have investigated how the external noise would influence the intracellular calcium signaling processes due to the existence of internal noise in small systems. Using chemical Langevin equations, we demonstrate numerically that the behavior of 'system size bi-resonance' induced by internal noise will change with the external noise intensity in different regions, indicating the occurrence of selective effects of external noise. Meanwhile, cell system may also automatically select an optimal cell size to obtain the best performance in the presence of external noise. These results may imply that such selective-effect phenomenon should have some inherent relevance with the distinct deterministic bifurcation features of the system.
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Affiliation(s)
- Hanshuang Chen
- College of Physics and Electronic Information, Anhui Normal University, Wuhu, Anhui, 241000, PR China
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41
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Wu D, Jia Y. Mean-field coupling of calcium oscillations in a multicellular system of rat hepatocytes. Biophys Chem 2007; 125:247-53. [PMID: 16978763 DOI: 10.1016/j.bpc.2006.08.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Revised: 08/15/2006] [Accepted: 08/16/2006] [Indexed: 11/27/2022]
Abstract
In a multicellular system of rat hepatocytes and even in an intact liver, cytoplasmic calcium oscillations are synchronized and highly coordinated. In this paper, the mean-field coupling term has been introduced to describe the coupling flux, which is more efficient than gap junctional coupling terms. An optimal coupling strength and an optimal stimulation level for the synchronization of the coupled system have been observed in this paper. Moreover, it has been proved that these results are independent of the cells number. Interestingly, it has been observed that the intracellular noise and the extracellular noise have different effects on the synchronization of the coupled system.
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Affiliation(s)
- Dan Wu
- Department of Physics and Institute of Biophysics, Central China Normal University, Wuhan 430079, China.
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42
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Vandeput F, Combettes L, Mills SJ, Backers K, Wohlkönig A, Parys JB, De Smedt H, Missiaen L, Dupont G, Potter BVL, Erneux C. Biphenyl 2,3′,4,5′,6‐pentakisphosphate, a novel inositol polyphosphate surrogate, modulates Ca2+responses in rat hepatocytes. FASEB J 2007; 21:1481-91. [PMID: 17264160 DOI: 10.1096/fj.06-7691com] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Benzene polyphosphates containing phosphate groups on one ring are Ins(1,4,5)P3 5-phosphatase inhibitors when evaluated against type-I Ins(1,4,5)P3 5-phosphatase. A novel biphenyl derivative, biphenyl 2,3',4,5',6-pentakisphosphate, with five phosphate groups on two rings was synthesized: It inhibited the activity of two inositol 5-phosphatases: type I and SHIP2 with Ins(1,3,4,5)P4 as substrate. The inhibition was competitive with respect to the substrate. IC50 value measured in rat hepatocytes, which contains the native Ins(1,4,5)P3 5-phosphatase, was in the micromolar range at 1.0 microM Ins(1,4,5)P3 as substrate. Biphenyl 2,3',4,5',6-pentakisphosphate did not affect the activity of Ins(1,4,5)P3 3-kinase A in the 5-100 microM range. Surprisingly, experimental evidence supports an effect of biphenyl 2,3',4,5',6-pentakisphosphate at the level of the Ins(1,4,5)P3 receptor. Finally, when injected into rat hepatocytes, the analog affected the frequency of Ca2+ oscillations in a positive or negative way depending on its concentration. At very high concentrations of the analog, Ca2+ oscillations were even suppressed. These data were interpreted as a dual effect of the biphenyl 2,3',4,5',6-pentakisphosphate on cytosolic [Ca2+] increases: an activation effect through an increase in Ins(1,4,5)P3 level via Ins(1,4,5)P3 5-phosphatase inhibition and an inhibitory effect, which was exerted directly on the Ins(1,4,5)P3 receptor. Thus, our data show for the first time that the frequency of Ca2+ oscillations in response to a Ca2+-mobilizing agonist can be controlled by inhibitors of type-I Ins(1,4,5)P3 5-phosphatase.
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Affiliation(s)
- Fabrice Vandeput
- Institut de Recherche Interdisciplinaire (IRIBHM), Université Libre de Bruxelles, Campus Erasme, 808 Route de Lennik, 1070 Brussels, Belgium
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43
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Zhu CL, Jia Y, Liu Q, Yang LJ, Zhan X. A mesoscopic stochastic mechanism of cytosolic calcium oscillations. Biophys Chem 2007; 125:201-12. [PMID: 16952419 DOI: 10.1016/j.bpc.2006.08.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2006] [Revised: 08/01/2006] [Accepted: 08/02/2006] [Indexed: 10/24/2022]
Abstract
Based on a model of intracellular calcium (Ca(2+)) oscillation with self-modulation of inositol 1,4,5-trisphosphate signal, the mesoscopic stochastic differential equations for the intracellular Ca(2+) oscillations are theoretically derived by using the chemical Langevin equation method. The effects of the finite biochemical reaction molecule number on both simple and complex cytosolic Ca(2+) oscillations are numerically studied. In the case of simple intracellular Ca(2+) oscillation, it is found that, with the increase of molecule number, the coherence resonance or autonomous resonance phenomena can occur for some external stimulation parameter values. In the cases of complex cytosolic Ca(2+) oscillations, each extremum of concentration of cytosolic Ca(2+) oscillations corresponds to a peak in the histogram of Ca(2+) concentration, and the most probability appeared during the bursting plateau level for bursting, but at the largest minimum of Ca(2+) concentration for chaos. For quasi-periodicity, however, there are only two peaks in the histogram of Ca(2+) concentration, and the most probability is located at low concentration state.
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Affiliation(s)
- Chun-Lian Zhu
- Department of Physics, Jianghan University, Wuhan 430056, China
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44
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Débarre D, Beaurepaire E. Quantitative characterization of biological liquids for third-harmonic generation microscopy. Biophys J 2006; 92:603-12. [PMID: 17085492 PMCID: PMC1751398 DOI: 10.1529/biophysj.106.094946] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Third-harmonic generation (THG) microscopy provides images of unstained biological samples based on spatial variations in third-order nonlinear susceptibility, refractive index, and dispersion. In this study, we establish quantitative values for the third-order nonlinear susceptibilities of several solvents (water, ethanol, glycerol), physiological aqueous (ions, amino acids, polypeptides, bovine serum albumin, glucose) and lipid (triglycerides, cholesterol) solutions as a function of solute concentration in the 1.05-1.25 microm excitation range. We use these data in conjunction with imaging experiments to show that THG imaging with approximately 1.2 microm excitation lacks specificity and sensitivity to detect physiological ion concentration changes, and that nonaqueous structures such as lipid bodies provide a more robust source of signal. Finally, we illustrate the impact of index-matching liquids in THG images. These data provide a basis for interpreting biological THG images and for developing additional applications.
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Affiliation(s)
- Delphine Débarre
- Laboratory for Optics and Biosciences, Ecole Polytechnique, CNRS, INSERM, Palaiseau, France
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45
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Brodsky VY, Zvezdina ND, Fateeva VI, Mal’chenko LA. Mechanism of direct cell interactions. Self-organization of protein synthesis rhythm. Russ J Dev Biol 2006. [DOI: 10.1134/s1062360406050055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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46
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Yamashita M. ‘Quantal’ Ca2+release reassessed - a clue to oscillation and synchronization. FEBS Lett 2006; 580:4979-83. [PMID: 16938295 DOI: 10.1016/j.febslet.2006.08.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Accepted: 08/14/2006] [Indexed: 11/26/2022]
Abstract
Ca(2+) release from intracellular Ca(2+) stores, a pivotal event in Ca(2+) signaling, is a 'quantal' process; it terminates after a rapid release of a fraction of stored Ca(2+). To explain the 'quantal' nature, 'all-or-none' model and 'steady-state' model were proposed. This article shortly reviews these hypotheses and considers a recently proposed mechanism, 'luminal potential' model, in which the membrane potential of Ca(2+) store regulates Ca(2+) efflux. By reassessing the 'quantal' nature, other important features of Ca(2+) signaling, oscillation and synchronization, are highlighted. The mechanism for 'quantal' Ca(2+) release may underlie the temporal and spatial control of Ca(2+) signaling.
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Affiliation(s)
- Masayuki Yamashita
- Department of Physiology I, Nara Medical University, Shijo-cho 840, Kashihara 634-8521, Japan.
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47
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Piazza V, Ciubotaru CD, Gale JE, Mammano F. Purinergic signalling and intercellular Ca2+ wave propagation in the organ of Corti. Cell Calcium 2006; 41:77-86. [PMID: 16828497 DOI: 10.1016/j.ceca.2006.05.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Revised: 05/09/2006] [Accepted: 05/14/2006] [Indexed: 11/26/2022]
Abstract
Extracellular ATP is a key neuromodulator of visual and auditory sensory epithelia. In the rat cochlea, pharmacological dissection indicates that ATP, acting through a highly sensitive purinergic/IP(3)-mediated signaling pathway with (little or) no involvement of ryanodine receptors, is the principal paracrine mediator implicated in the propagation of calcium waves through supporting and epithelial cells. Measurement of sensitivity to UTP and other purinergic agonists implicate P2Y(2) and P2Y(4) as the main P2Y receptor isoforms involved in these responses. Ca2+ waves, elicited under highly reproducible conditions by carefully controlling dose (1 microM) and timing of focal agonist application (0.2s), extended over radial distance greater than 160 microm from the source, identical to those activated by damaging single outer hair cells. Altogether, these results indicate that intercellular calcium waves are a robust phenomenon that confers a significant ability for cell-cell communication in the mammalian cochlea. Further ongoing research will reveal the roles that such Ca2+ waves play in the inner ear.
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Affiliation(s)
- Valeria Piazza
- Venetian Institute of Molecular Medicine, Foundation for Advanced Biomedical Research, via G. Orus 2, 35129 Padua, Italy
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48
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Sekine S, Ito K, Horie T. Oxidative stress and Mrp2 internalization. Free Radic Biol Med 2006; 40:2166-74. [PMID: 16785030 DOI: 10.1016/j.freeradbiomed.2006.02.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2005] [Revised: 02/18/2006] [Accepted: 02/21/2006] [Indexed: 10/24/2022]
Abstract
Oxidative stress in the liver is sometimes accompanied by cholestasis. We have described the internalization of multidrug resistance-associated protein 2/ATP-binding cassette transporter family 2 (Mrp2/Abcc2), a biliary transporter involved in bile-salt-independent bile flow, under ethacrynic acid (EA)-induced acute oxidative stress in rat liver. However, the signaling pathway and regulatory molecules have not been investigated. In the present study, we investigated the mechanism of EA-induced Mrp2 internalization using isolated rat hepatocyte couplets (IRCHs). The Mrp2 index, defined as the ratio of Mrp2-positive canalicular membrane staining in IRCHs per number of cell nuclei, was significantly reduced by treatment with EA. This reduction was abolished by a nonspecific protein kinase C (PKC) inhibitor Gö6850, a Ca(2+) chelator, EGTA, but not by a protein kinase A (PKA)-selective inhibitor, a Ca(2+)-dependent conventional PKC (cPKC) inhibitor Gö6976, or a protein kinase G (PKG) inhibitor (1 microM). Moreover, an increase in the intracellular Ca(2+) level and NO release into medium were observed shortly after the EA treatment. Both of these increases, as well as Mrp2 internalization, were completely blocked by EGTA. In conclusion, EA produced a reduction in GSH, Ca(2+) elevation, NO production, and nPKC activation in a sequential manner, finally leading to Mrp2 internalization.
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Affiliation(s)
- Shuichi Sekine
- Laboratory of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chiba, 260-8675, Japan
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49
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Koukoui O, Boucherie S, Sezan A, Prigent S, Combettes L. Effects of the prostaglandins PGF2alpha and PGE2 on calcium signaling in rat hepatocyte doublets. Am J Physiol Gastrointest Liver Physiol 2006; 290:G66-73. [PMID: 16081764 DOI: 10.1152/ajpgi.00088.2005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Coordination of intercellular Ca2+ signals is important for certain hepatic functions including biliary flow and glucose output. Prostaglandins, such as PGF2alpha and PGE2, may modify these hepatocyte functions by inducing Ca2+ increase, but very little is known about the organization of the Ca2+ signals induced by these agonists. We studied Ca2+ signals induced by PGF2alpha and PGE2 in fura-2 AM-loaded hepatocyte doublets. Even though both prostaglandins induced Ca2+ oscillations, neither PGF2alpha nor PGE2 induced coordinated Ca2+ oscillations in hepatocyte doublets. Gap junction permeability (GJP), assessed by fluorescence recovery after photobleaching, showed that this absence of coordination was not related to a defect in GJP. Inositol (1,4,5)trisphosphate [Ins(1,4,5)P3] assays and the increase in Ins(1,4,5)P3 receptor sensitivity to Ins(1,4,5)P3 observed in response to thimerosal suggested that the absence of coordination was a consequence of the very small quantity of Ins(1,4,5)P3 formed by these prostaglandins. Furthermore, when PGE2 and PGF2alpha were added just before norepinephrine, they favored the coordination of Ca2+ signals induced by norepinephrine. However, GJP between hepatocyte doublets was strongly inhibited by prolonged (>or=2 h) treatment with PGF2alpha, thereby preventing the coordination of Ca2+ oscillations induced by norepinephrine in these cells. Thus, depending on the time window, prostaglandins, specially PGF2alpha, may enhance or diminish the propagation of Ca2+ signals. They may therefore contribute to the fine tuning of Ca2+ wave-dependent functions, such as nerve stimulation, hormonal regulation of liver metabolism, or bile secretion, in both normal and pathogenic conditions.
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Affiliation(s)
- O Koukoui
- Institut National de la Santé et de la Recherche Médicale Unité 442, Bâtiment 443, Université Paris-Sud, 15 rue Georges Clémenceau, 91405 Orsay cedex, France
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50
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Brodsky VY. Direct cell-cell communication: a new approach derived from recent data on the nature and self-organisation of ultradian (circahoralian) intracellular rhythms. Biol Rev Camb Philos Soc 2005; 81:143-62. [PMID: 16336746 DOI: 10.1017/s1464793105006937] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 09/14/2005] [Accepted: 09/21/2005] [Indexed: 11/07/2022]
Abstract
Recent data concerning ultradian (circahoralian) intracellular rhythms are used to assess the biochemical mechanisms of direct cell-cell communication. New results and theoretical considerations suggest a fractal nature of ultradian rhythms and their self-organisation. The fundamental and innate nature of these rhythms relates to their self-similarity at different levels of cell and tissue organisation. They can be detected in cell-free systems as well as in cells and organs in vivo. Such rhythms are a means of finding an optimal state of cell function rather than achieving a state of absolute stability. As a consequence, oscillations, being irregular and numerous by the set of periods, are resilient to functional overload and injury. Recent data on the maintenance of their fractal structure and, especially on the selection of optimal periods are discussed. The positive role of chaotic dynamics is stressed. The ultradian rhythm of protein synthesis in hepatocytes in vitro was used as a marker of direct cell-cell communication. The system demonstrates cell cooperation and synchronisation throughout the cell population, and suggests that the ultradian rhythms are self-organised. These observations also led to the detection of mechanisms of direct cell-cell communication in which extracellular factors have an essential role. Experimental evidence indicated the involvement of gangliosides and/or catecholamines in this large-scale synchronisation of protein synthesis. The response of all, or a major part, of the cell population is important; after the initial trigger effect, a periodic pattern is retained for some time. The influence of Ca2+-dependent protein kinases on protein phosphorylation can be a final step in the phase modulation of rhythms during cell-cell synchronisation. The intercellular medium plays an important role in self-synchronisation of ultradian rhythms between individual cells. Low cooperative activity of hepatocytes of old rats resulted from altered composition of the intercellular medium rather than direct effects of animal and cellular ageing. Similarly, in the whole body, changes in levels of gangliosides and catecholamines in the blood serum, a natural intercellular medium, can be critical events in age-dependent changes of the serum and accordingly cell-cell synchronisation. Hepatocytes of old rats exhibit some of the properties of young cells following an increase in blood serum ganglioside level, as well as, in in vitro conditions, after the addition of gangliosides to the culture medium. Together with data on ultradian functional and metabolic rhythms, all the material reviewed here allows us to propose a mechanism of direct cell-cell cooperation via the medium in which the cells exist, that supplements the nervous and hormonal central regulation of organ functions. Ultradian intracellular rhythms may thus provide a finer framework within which the integrated dynamics of respiration, heart rate, brain activity, and even behavioural patterns, are brought to an optimal functional pattern. Innate and direct cell-cell cooperation may have been employed as a means of intercellular regulation during the course of metazoan evolution, that preceded nervous regulation and is presently retained in mammals.
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Affiliation(s)
- Vsevolod Ya Brodsky
- Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilov St., Moscow, GSP-1 119991, Russia.
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