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Silva IS, Almeida AD, Lima Filho ACM, Fernandes-Braga W, Barra A, Oliveira HMC, Cassali GD, Capettini LSA, Menezes GB, Alvarez-Leite JI, Leite MF, Klein A. Platelet-activating factor and protease-activated receptor 2 cooperate to promote neutrophil recruitment and lung inflammation through nuclear factor-kappa B transactivation. Sci Rep 2023; 13:21637. [PMID: 38062077 PMCID: PMC10703791 DOI: 10.1038/s41598-023-48365-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 11/25/2023] [Indexed: 12/18/2023] Open
Abstract
Although it is well established that platelet-activated receptor (PAF) and protease-activated receptor 2 (PAR2) play a pivotal role in the pathophysiology of lung and airway inflammatory diseases, a role for a PAR2-PAFR cooperation in lung inflammation has not been investigated. Here, we investigated the role of PAR2 in PAF-induced lung inflammation and neutrophil recruitment in lungs of BALB/c mice. Mice were pretreated with the PAR2 antagonist ENMD1068, PAF receptor (PAFR) antagonist WEB2086, or aprotinin prior to intranasal instillation of carbamyl-PAF (C-PAF) or the PAR2 agonist peptide SLIGRL-NH2 (PAR2-AP). Leukocyte infiltration in bronchoalveolar lavage fluid (BALF), C-X-C motif ligand 1 (CXCL)1 and CXCL2 chemokines, myeloperoxidase (MPO), and N-acetyl-glycosaminidase (NAG) levels in BALF, or lung inflammation were evaluated. Intracellular calcium signaling, PAFR/PAR2 physical interaction, and the expression of PAR2 and nuclear factor-kappa B (NF-КB, p65) transcription factor were investigated in RAW 264.7 cells stimulated with C-PAF in the presence or absence of ENMD1068. C-PAF- or PAR2-AP-induced neutrophil recruitment into lungs was inhibited in mice pretreated with ENMD1068 and aprotinin or WEB2086, respectively. PAR2 blockade impaired C-PAF-induced neutrophil rolling and adhesion, lung inflammation, and production of MPO, NAG, CXCL1, and CXCL2 production in lungs of mice. PAFR activation reduced PAR2 expression and physical interaction of PAR2 and PAFR; co-activation is required for PAFR/PAR2 physical interaction. PAR2 blockade impaired C-PAF-induced calcium signal and NF-κB p65 translocation in RAW 264.7 murine macrophages. This study provides the first evidence for a cooperation between PAFR and PAR2 mediating neutrophil recruitment, lung inflammation, and macrophage activation.
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Affiliation(s)
- Irismara Sousa Silva
- Laboratory of Inflammation and Proteases, Department of Pharmacology, Institute of Biological Sciences (ICB), Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil
| | - Aline D Almeida
- Laboratory of Inflammation and Proteases, Department of Pharmacology, Institute of Biological Sciences (ICB), Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil
| | | | - Weslley Fernandes-Braga
- Laboratory of Atherosclerosis and Nutritional Biochemistry (LABIN-UFMG), Department of Biochemistry and Immunology, ICB/UFMG, Belo Horizonte, Minas Gerais, Brazil
| | - Ayslan Barra
- Laboratory of Inflammation and Proteases, Department of Pharmacology, Institute of Biological Sciences (ICB), Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil
| | | | | | - Luciano S A Capettini
- Laboratory of Vascular Biology, Department of Pharmacology, ICB/UFMG, Belo Horizonte, Minas Gerais, Brazil
| | - Gustavo B Menezes
- Department of Morphology, ICB/UFMG, Belo Horizonte, Minas Gerais, Brazil
| | - Jacqueline I Alvarez-Leite
- Laboratory of Atherosclerosis and Nutritional Biochemistry (LABIN-UFMG), Department of Biochemistry and Immunology, ICB/UFMG, Belo Horizonte, Minas Gerais, Brazil
| | - Maria F Leite
- Department of Physiology and Biophysics, ICB/UFMG, Belo Horizonte, Minas Gerais, Brazil
| | - André Klein
- Laboratory of Inflammation and Proteases, Department of Pharmacology, Institute of Biological Sciences (ICB), Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil.
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Receptor-specific Ca 2+ oscillation patterns mediated by differential regulation of P2Y purinergic receptors in rat hepatocytes. iScience 2021; 24:103139. [PMID: 34646983 PMCID: PMC8496176 DOI: 10.1016/j.isci.2021.103139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 07/26/2021] [Accepted: 09/14/2021] [Indexed: 11/21/2022] Open
Abstract
Extracellular agonists linked to inositol-1,4,5-trisphosphate (IP3) formation elicit cytosolic Ca2+ oscillations in many cell types, but despite a common signaling pathway, distinct agonist-specific Ca2+ spike patterns are observed. Using qPCR, we show that rat hepatocytes express multiple purinergic P2Y and P2X receptors (R). ADP acting through P2Y1R elicits narrow Ca2+ oscillations, whereas UTP acting through P2Y2R elicits broad Ca2+ oscillations, with composite patterns observed for ATP. P2XRs do not play a role at physiological agonist levels. The discrete Ca2+ signatures reflect differential effects of protein kinase C (PKC), which selectively modifies the falling phase of the Ca2+ spikes. Negative feedback by PKC limits the duration of P2Y1R-induced Ca2+ spikes in a manner that requires extracellular Ca2+. By contrast, P2Y2R is resistant to PKC negative feedback. Thus, the PKC leg of the bifurcated IP3 signaling pathway shapes unique Ca2+ oscillation patterns that allows for distinct cellular responses to different agonists. Distinct stereotypic Ca2+ oscillations are elicited by P2Y1 and P2Y2 receptors P2X receptors do not contribute to the generation of Ca2+ oscillations Agonist-specific Ca2+ spike shapes reflect discrete modes of PKC negative feedback Bifurcation of IP3/PKC signaling yields unique Ca2+ oscillation signatures
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Rysted JE, Lin Z, Walters GC, Rauckhorst AJ, Noterman M, Liu G, Taylor EB, Strack S, Usachev YM. Distinct properties of Ca 2+ efflux from brain, heart and liver mitochondria: The effects of Na +, Li + and the mitochondrial Na +/Ca 2+ exchange inhibitor CGP37157. Cell Calcium 2021; 96:102382. [PMID: 33684833 DOI: 10.1016/j.ceca.2021.102382] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 10/22/2022]
Abstract
Mitochondrial Ca2+ transport is essential for regulating cell bioenergetics, Ca2+ signaling and cell death. Mitochondria accumulate Ca2+ via the mitochondrial Ca2+ uniporter (MCU), whereas Ca2+ is extruded by the mitochondrial Na+/Ca2+ (mtNCX) and H+/Ca2+ exchangers. The balance between these processes is essential for preventing toxic mitochondrial Ca2+ overload. Recent work demonstrated that MCU activity varies significantly among tissues, likely reflecting tissue-specific Ca2+ signaling and energy needs. It is less clear whether this diversity in MCU activity is matched by tissue-specific diversity in mitochondrial Ca2+ extrusion. Here we compared properties of mitochondrial Ca2+ extrusion in three tissues with prominent mitochondria function: brain, heart and liver. At the transcript level, expression of the Na+/Ca2+/Li+ exchanger (NCLX), which has been proposed to mediate mtNCX transport, was significantly greater in liver than in brain or heart. At the functional level, Na+ robustly activated Ca2+ efflux from brain and heart mitochondria, but not from liver mitochondria. The mtNCX inhibitor CGP37157 blocked Ca2+ efflux from brain and heart mitochondria but had no effect in liver mitochondria. Replacement of Na+ with Li+ to test the involvement of NCLX, resulted in a slowing of mitochondrial Ca2+ efflux by ∼70 %. Collectively, our findings suggest that mtNCX is responsible for Ca2+ extrusion from the mitochondria of the brain and heart, but plays only a small, if any, role in mitochondria of the liver. They also reveal that Li+ is significantly less effective than Na+ in driving mitochondrial Ca2+ efflux.
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Affiliation(s)
- Jacob E Rysted
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa College of Medicine, Iowa City, IA, 52242, USA
| | - Zhihong Lin
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa College of Medicine, Iowa City, IA, 52242, USA
| | - Grant C Walters
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa College of Medicine, Iowa City, IA, 52242, USA
| | - Adam J Rauckhorst
- Department of Molecular Physiology and Biophysics, University of Iowa College of Medicine, Iowa City, IA, 52242, USA
| | - Maria Noterman
- Department of Molecular Physiology and Biophysics, University of Iowa College of Medicine, Iowa City, IA, 52242, USA
| | - Guanghao Liu
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, IA, 52242, USA
| | - Eric B Taylor
- Department of Molecular Physiology and Biophysics, University of Iowa College of Medicine, Iowa City, IA, 52242, USA
| | - Stefan Strack
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa College of Medicine, Iowa City, IA, 52242, USA
| | - Yuriy M Usachev
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa College of Medicine, Iowa City, IA, 52242, USA.
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Abstract
Extracellular nucleosides and nucleotides activate a group of G protein-coupled receptors (GPCRs) known as purinergic receptors, comprising adenosine and P2Y receptors. Furthermore, purinergic P2X ion channels are activated by ATP. These receptors are expressed in liver resident cells and play a critical role in maintaining liver function. In the normal physiology, these receptors regulate hepatic metabolic processes such as insulin responsiveness, glycogen and lipid metabolism, and bile secretion. In disease states, ATP and other nucleotides serve as danger signals and modulate purinergic responses in the cells. Recent studies have demonstrated that purinergic receptors play a significant role in the development of metabolic syndrome associated non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), fibrosis, hepatocellular carcinoma (HCC) and liver inflammation. In this concise review, we dissect the role of purinergic signaling in different liver resident cells involved in maintaining healthy liver function and in the development of the above-mentioned liver pathologies. Moreover, we discuss potential therapeutic strategies for liver diseases by targeting adenosine, P2Y and P2X receptors.
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Vats N, Dubey RC, Sanal MG, Taneja P, Venugopal SK. Glibenclamide, ATP and metformin increases the expression of human bile salt export pump ABCB11. F1000Res 2020; 9:1497. [PMID: 33763207 PMCID: PMC7953918 DOI: 10.12688/f1000research.26632.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/02/2020] [Indexed: 12/30/2022] Open
Abstract
Background: Bile salt export pump (BSEP/ABCB11) is important in the maintenance of the enterohepatic circulation of bile acids and drugs. Drugs such as rifampicin and glibenclamide inhibit BSEP. Progressive familial intrahepatic cholestasis type-2, a lethal pediatric disease, some forms of intrahepatic cholestasis of pregnancy, and drug-induced cholestasis are associated with BSEP dysfunction. Methods: We started with a bioinformatic approach to identify the relationship between ABCB11 and other proteins, microRNAs, and drugs. A microarray data set of the liver samples from ABCB11 knockout mice was analyzed using GEO2R. Differentially expressed gene pathway enrichment analysis was conducted using ClueGo. A protein-protein interaction network was constructed using STRING application in Cytoscape. Networks were analyzed using Cytoscape. CyTargetLinker was used to screen the transcription factors, microRNAs and drugs. Predicted drugs were validated on human liver cell line, HepG2. BSEP expression was quantified by real-time PCR and western blotting. Results:ABCB11 knockout in mice was associated with a predominant upregulation and downregulation of genes associated with cellular component movement and sterol metabolism, respectively. We further identified the hub genes in the network. Genes related to immune activity, cell signaling, and fatty acid metabolism were dysregulated. We further identified drugs (glibenclamide and ATP) and a total of 14 microRNAs targeting the gene. Western blot and real-time PCR analysis confirmed the upregulation of BSEP on the treatment of HepG2 cells with glibenclamide, ATP, and metformin. Conclusions: The differential expression of cell signaling genes and those related to immune activity in
ABCB11 KO animals may be secondary to cell injury. We have found glibenclamide, ATP, and metformin upregulates BSEP. The mechanisms involved and the clinical relevance of these findings need to be investigated.
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Affiliation(s)
- Nisha Vats
- Department of Molecular and Cellular Medicine, Institute of Liver and Biliary Sciences, New Delhi, Delhi, 110070, India
| | - Ravi Chandra Dubey
- Department of Life Sciences, South Asian University, New Delhi, Delhi, 110021, India
| | - Madhusudana Girija Sanal
- Department of Molecular and Cellular Medicine, Institute of Liver and Biliary Sciences, New Delhi, Delhi, 110070, India
| | - Pankaj Taneja
- Department of Biotechnology, Sharda University, Noida, Uttar Pradesh, 201310, India
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de Almeida AD, Silva IS, Fernandes-Braga W, LimaFilho ACM, Florentino ROM, Barra A, de Oliveira Andrade L, Leite MF, Cassali GD, Klein A. A role for mast cells and mast cell tryptase in driving neutrophil recruitment in LPS-induced lung inflammation via protease-activated receptor 2 in mice. Inflamm Res 2020; 69:1059-1070. [PMID: 32632517 DOI: 10.1007/s00011-020-01376-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 06/04/2020] [Accepted: 07/02/2020] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE This study aims to investigate the role of protease-activated receptor (PAR) 2 and mast cell (MC) tryptase in LPS-induced lung inflammation and neutrophil recruitment in the lungs of C57BL/6 mice. METHODS C57BL/6 mice were pretreated with the PAR2 antagonist ENMD-1068, compound 48/80 or aprotinin prior to intranasal instillation of MC tryptase or LPS. Blood leukocytes, C-X-C motif chemokine ligand (CXCL) 1 production leukocytes recovered from bronchoalveolar lavage fluid (BALF), and histopathological analysis of the lung were evaluated 4 h later. Furthermore, we performed experiments to determine intracellular calcium signaling in RAW 264.7 cells stimulated with LPS in the presence or absence of a protease inhibitor cocktail or ENMD-1068 and evaluated PAR2 expression in the lungs of LPS-treated mice. RESULTS Pharmacological blockade of PAR2 or inhibition of proteases reduced neutrophils recovered in BALF and LPS-induced calcium signaling. PAR2 blockade impaired LPS-induced lung inflammation, PAR2 expression in the lung and CXCL1 release in BALF, and increased circulating blood neutrophils. Intranasal instillation of MC tryptase increased the number of neutrophils recovered in BALF, and MC depletion with compound 48/80 impaired LPS-induced neutrophil migration. CONCLUSION Our study provides, for the first time, evidence of a pivotal role for MCs and MC tryptase in neutrophil migration, lung inflammation and macrophage activation triggered by LPS, by a mechanism dependent on PAR2 activation.
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Affiliation(s)
- Aline Dias de Almeida
- Laboratory of Pain and Inflammation, Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), Av. Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, 31270-010, Brazil
| | - Irismara Sousa Silva
- Laboratory of Pain and Inflammation, Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), Av. Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, 31270-010, Brazil
| | - Weslley Fernandes-Braga
- Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Antônio Carlos Melo LimaFilho
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - R Odrigo Machado Florentino
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Ayslan Barra
- Laboratory of Pain and Inflammation, Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), Av. Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, 31270-010, Brazil
| | - Luciana de Oliveira Andrade
- Department of Morphology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - M Fátima Leite
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Geovanni Dantas Cassali
- Department of Pathology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - André Klein
- Laboratory of Pain and Inflammation, Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais (UFMG), Av. Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, 31270-010, Brazil.
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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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Franca A, Filho ACML, Guerra MT, Weerachayaphorn J, dos Santos ML, Njei B, Robert M, Lima CX, Vidigal PVT, Banales JM, Ananthanarayanam M, Leite MF, Nathanson MH. Effects of Endotoxin on Type 3 Inositol 1,4,5-Trisphosphate Receptor in Human Cholangiocytes. Hepatology 2019; 69:817-830. [PMID: 30141207 PMCID: PMC6351171 DOI: 10.1002/hep.30228] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 08/13/2018] [Indexed: 12/16/2022]
Abstract
Clinical conditions that result in endotoxemia, such as sepsis and alcoholic hepatitis (AH), often are accompanied by cholestasis. Although hepatocellular changes in response to lipopolysaccharide (LPS) have been well characterized, less is known about whether and how cholangiocytes contribute to this form of cholestasis. We examined effects of endotoxin on expression and function of the type 3 inositol trisphosphate receptor (ITPR3), because this is the main intracellular Ca2+ release channel in cholangiocytes, and loss of it impairs ductular bicarbonate secretion. Bile duct cells expressed the LPS receptor, Toll-like receptor 4 (TLR4), which links to activation of nuclear factor-κB (NF-κB). Analysis of the human ITPR3 promoter revealed five putative response elements to NF-κB, and promoter activity was inhibited by p65/p50. Nested 0.5- and 1.0-kilobase (kb) deletion fragments of the ITPR3 promoter were inhibited by NF-κB subunits. Chromatin immunoprecipitation (ChIP) assay showed that NF-κB interacts with the ITPR3 promoter, with an associated increase in H3K9 methylation. LPS decreased ITPR3 mRNA and protein expression and also decreased sensitivity of bile duct cells to calcium agonist stimuli. This reduction was reversed by inhibition of TLR4. ITPR3 expression was decreased or absent in cholangiocytes from patients with cholestasis of sepsis and from those with severe AH. Conclusion: Stimulation of TLR4 by LPS activates NF-κB to down-regulate ITPR3 expression in human cholangiocytes. This may contribute to the cholestasis that can be observed in conditions such as sepsis or AH.
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Affiliation(s)
- Andressa Franca
- Federal University of Minas Gerais (UFMG), Belo Horizonte, MG
| | | | - Mateus T. Guerra
- Section of Digestive Disease, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Jittima Weerachayaphorn
- Section of Digestive Disease, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT,Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | | | - Basile Njei
- Section of Digestive Disease, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
| | - Marie Robert
- Department of Pathology, Yale University School of Medicine, New Haven, CT
| | | | | | - Jesus M. Banales
- Department of Liver and Gastrointestinal Diseases, Biodonostia Research Institute, Donostia University Hospital, University of the Basque Country (UPV/EHU), San Sebastian, Spain
| | | | - M. Fatima Leite
- Federal University of Minas Gerais (UFMG), Belo Horizonte, MG
| | - Michael H. Nathanson
- Section of Digestive Disease, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
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Rodrigues MA, Gomes DA, Nathanson MH. Calcium Signaling in Cholangiocytes: Methods, Mechanisms, and Effects. Int J Mol Sci 2018; 19:ijms19123913. [PMID: 30563259 PMCID: PMC6321159 DOI: 10.3390/ijms19123913] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 11/13/2018] [Accepted: 11/20/2018] [Indexed: 02/06/2023] Open
Abstract
Calcium (Ca2+) is a versatile second messenger that regulates a number of cellular processes in virtually every type of cell. The inositol 1,4,5-trisphosphate receptor (ITPR) is the only intracellular Ca2+ release channel in cholangiocytes, and is therefore responsible for Ca2+-mediated processes in these cells. This review will discuss the machinery responsible for Ca2+ signals in these cells, as well as experimental models used to investigate cholangiocyte Ca2+ signaling. We will also discuss the role of Ca2+ in the normal and abnormal regulation of secretion and apoptosis in cholangiocytes, two of the best characterized processes mediated by Ca2+ in this cell type.
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Affiliation(s)
- Michele Angela Rodrigues
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520-8019, USA.
| | - Dawidson Assis Gomes
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520-8019, USA.
- Department of Biochemistry and Immunology, Federal University of Minas Gerais. Av. Antônio Carlos, 6627, Belo Horizonte-MG 31270-901, Brazil.
| | - Michael Harris 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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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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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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12
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Abstract
Astrocytes are activated during both excitatory and inhibitory synaptic transmission and respond with intracellular Ca2+i elevations. Ca2+i oscillations and waves in astrocytes now appear to represent the glial arm of a dynamic neuronal-glial signaling process. Advances within the last year have shown that stimuli that elevate Ca2+i in astrocytes have the potential to modulate synaptic function. Recent studies have shown that astrocytic calcium waves, initially believed to depend on the integrity of functional gap junction channels for the passage of intercellular signals, are actually mediated by release of ATP and subsequent activation of purinergic receptors on neighboring cells. ATP release is in turn regulated by the expression of gap junction proteins, establishing a novel dimension between gap junctions and extracellular-mediated signaling events. The role of ATP and its breakdown product, adenosine, on synaptic transmission are discussed.
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Affiliation(s)
- M. L. Cotrina
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York
| | - M. Nedergaard
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York
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13
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Kim JH. Effects of portal hyperperfusion on partial liver grafts in the presence of hyperdynamic splanchnic circulation: hepatic regeneration versus portal hyperperfusion injury. Anesth Pain Med (Seoul) 2016. [DOI: 10.17085/apm.2016.11.2.117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Jong Hae Kim
- Department of Anesthesiology and Pain Medicine, School of Medicine, Catholic University of Daegu, Daegu, Korea
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14
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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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15
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Hellerbrand C, Schattenberg JM, Peterburs P, Lechner A, Brignoli R. The potential of silymarin for the treatment of hepatic disorders. CLINICAL PHYTOSCIENCE 2016. [DOI: 10.1186/s40816-016-0019-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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16
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Li Q, Zhang Y, Pluchon P, Robens J, Herr K, Mercade M, Thiery JP, Yu H, Viasnoff V. Extracellular matrix scaffolding guides lumen elongation by inducing anisotropic intercellular mechanical tension. Nat Cell Biol 2016; 18:311-8. [PMID: 26878396 DOI: 10.1038/ncb3310] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 01/08/2016] [Indexed: 02/07/2023]
Abstract
The de novo formation of secretory lumens plays an important role during organogenesis. It involves the establishment of a cellular apical pole and the elongation of luminal cavities. The molecular parameters controlling cell polarization have been heavily scrutinized. In particular, signalling from the extracellular matrix (ECM) proved essential to the proper localization of the apical pole by directed protein transport. However, little is known about the regulation of the shape and the directional development of lumen into tubes. We demonstrate that the spatial scaffolding of cells by ECM can control tube shapes and can direct their elongation. We developed a minimal organ approach comprising of hepatocyte doublets cultured in artificial microniches to precisely control the spatial organization of cellular adhesions in three dimensions. This approach revealed a mechanism by which the spatial repartition of integrin-based adhesion can elicit an anisotropic intercellular mechanical stress guiding the osmotically driven elongation of lumens in the direction of minimal tension. This mechanical guidance accounts for the different morphologies of lumen in various microenvironmental conditions.
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Affiliation(s)
- Qiushi Li
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Yue Zhang
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Perrine Pluchon
- Department of Biological Sciences, National University of Singapore, Singapore 117411, Singapore
| | - Jeffrey Robens
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Keira Herr
- Institute of Molecular Cell Biology, A∗STAR, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Myriam Mercade
- Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés, Université de Toulouse, INSA, INRA, CNRS, 31077 Toulouse, France
| | - Jean-Paul Thiery
- Institute of Molecular Cell Biology, A∗STAR, 61 Biopolis Drive, Singapore 138673, Singapore
| | - Hanry Yu
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.,Department of Physiology, Yong Loo Lin School of Medicine, National University Health System, Singapore 117597, Singapore.,Institute of Bioengineering and Nanotechnology (IBN), Agency for Science, Technology and Research, Singapore 138669, Singapore
| | - Virgile Viasnoff
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore 117411, Singapore.,Institute of Molecular Cell Biology, A∗STAR, 61 Biopolis Drive, Singapore 138673, Singapore.,CNRS UMI3639, Singapore 117411, Singapore
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17
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Hansson E, Skiöldebrand E. Coupled cell networks are target cells of inflammation, which can spread between different body organs and develop into systemic chronic inflammation. JOURNAL OF INFLAMMATION-LONDON 2015. [PMID: 26213498 PMCID: PMC4514450 DOI: 10.1186/s12950-015-0091-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Several organs in the body comprise cells coupled into networks. These cells have in common that they are excitable but do not express action potentials. Furthermore, they are equipped with Ca2+ signaling systems, which can be intercellular and/or extracellular. The transport of small molecules between the cells occurs through gap junctions comprising connexin 43. Examples of cells coupled into networks include astrocytes, keratinocytes, chondrocytes, synovial fibroblasts, osteoblasts, connective tissue cells, cardiac and corneal fibroblasts, myofibroblasts, hepatocytes, and different types of glandular cells. These cells are targets for inflammation, which can be initiated after injury or in disease. If the inflammation reaches the CNS, it develops into neuroinflammation and can be of importance in the development of systemic chronic inflammation, which can manifest as pain and result in changes in the expression and structure of cellular components. Biochemical parameters of importance for cellular functions are described in this review.
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Affiliation(s)
- Elisabeth Hansson
- Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Per Dubbsgatan 14, 1tr, , SE 413 45 Gothenburg, Sweden
| | - Eva Skiöldebrand
- Section of Pathology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden ; Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska University Hospital, Gothenburg University, Gothenburg, Sweden
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18
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Guerra MT, Nathanson MH. Calcium signaling and secretion in cholangiocytes. Pancreatology 2015; 15:S44-8. [PMID: 26100660 PMCID: PMC4603373 DOI: 10.1016/j.pan.2015.05.477] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 05/08/2015] [Accepted: 05/27/2015] [Indexed: 12/11/2022]
Abstract
Alcoholic hepatitis affects up to one-third of individuals who abuse alcohol and can be associated with high mortality. Although this disorder is characterized by hepatocellular damage, steatosis and neutrophil infiltration, recent evidence suggests that cholestasis or impaired bile secretion may be a frequent occurrence as well. Bile secretion results from the concerted activity of hepatocytes and cholangiocytes, the epithelial cells that line the bile ducts. Hepatocytes secrete bile acids and conjugated products into the bile canaliculi, which then are modified by cholangiocytes through secretion of bicarbonate and water to give rise to the final secreted bile. Here the molecular mechanisms regulating bile secretion in cholangiocytes are reviewed. Moreover, we discuss how the expression of intracellular Ca(2+) channels might be regulated in cholangiocytes, plus evidence that components of the Ca(2+) signaling machinery are altered in a range of cholestatic diseases of the bile ducts.
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Affiliation(s)
- Mateus T. Guerra
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine
| | - Michael H. Nathanson
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine,Correspondence to: Michael H. Nathanson, 300 Cedar Street, TAC S241D, New Haven, CT. USA. 06520-8019, Phone: +1 203 785 7312, Fax: +1 203 785 7273,
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19
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Poupon R. Liver alkaline phosphatase: a missing link between choleresis and biliary inflammation. Hepatology 2015; 61:2080-90. [PMID: 25603770 DOI: 10.1002/hep.27715] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/16/2015] [Indexed: 02/06/2023]
Abstract
Several lines of evidence show that serum alkaline phosphatase (AP) is not only a signpost of cholestasis but also a surrogate marker of the severity of primary biliary cirrhosis and primary sclerosing cholangitis. In the present opinion article, we review and discuss the putative role of liver AP in health and in cholestatic diseases. In inflammatory cholestatic conditions, loss of activity of liver AP (resulting from its relocation from canaliculi and the acidic milieu) might promote hyper-adenosine triphosphate-bilia, lipopolysaccharide overload, and subsequent exacerbation and perpetuation of inflammation. Drugs that can restore the polarity of hepatocytes and canalicular export of bile acids or act as bile alkalinity modifiers are predicted to exert anti-inflammatory effects and to benefit both primary biliary cirrhosis and primary sclerosing cholangitis. Oral administration of intestinal AP could be a valid therapeutic intervention that deserves further study under experimental conditions as well as in human diseases. Overall, the key role of the liver microenvironment that might shape the different facets of the inflammatory processes in fibrosing cholangiopathies is highlighted.
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Affiliation(s)
- Raoul Poupon
- UPMC University of Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Paris, France.,AP-HP, Hôpital Saint-Antoine, Service d'Hépatologie, Paris, France
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20
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Jan KC, Yang BB, Liu TC. Gene expression profiling of sesaminol triglucoside and its tetrahydrofuranoid metabolites in primary rat hepatocytes. Int J Food Sci Nutr 2014; 65:981-8. [PMID: 25156454 DOI: 10.3109/09637486.2014.950204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Sesaminol triglucoside is a major lignin in sesame meal and has a methylenedioxyphenyl group and multiple functions in vivo. As a tetrahydrofurofuran type lignan, sesaminol triglucoside is metabolized to mammalian lignans. This investigation studies the effect of sesaminol triglucoside and its tetrahydrofuranoid metabolites (sesaminol, 2-episesaminol, hydroxymethyl sesaminol-tetrahydrofuran, enterolactone, and enterodiol) on gene expression in primary rat hepatocytes using a DNA microarray. Sesame lignans significantly affected the expression of xenobiotic-induced transcripts of cytochrome P450, solute carrier (SLC), and ATP-binding cassette (ABC) transporters. Changes in gene expression were generally greater in response to metabolites with methylenedioxyphenyl moieties (sesaminol triglucoside, sesaminol, and 2-episesaminol) than to the tetrahydrofuranoid metabolites (hydroxymethyl sesaminol-tetrahydrofuran, enterolactone, and enterodiol). Tetrahydrofuran lignans, such as sesaminol triglucoside, sesamin, hydroxymethyl sesaminol-tetrahydrofuran, and sesaminol changed the expression of ABC transporters.
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Affiliation(s)
- Kuo-Ching Jan
- Food Industry Research & Development Institute , Hsinchu , Taiwan and
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21
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Wang CM, Ploia C, Anselmi F, Sarukhan A, Viola A. Adenosine triphosphate acts as a paracrine signaling molecule to reduce the motility of T cells. EMBO J 2014; 33:1354-64. [PMID: 24843045 DOI: 10.15252/embj.201386666] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Organization of immune responses requires exchange of information between cells. This is achieved through either direct cell-cell contacts and establishment of temporary synapses or the release of soluble factors, such as cytokines and chemokines. Here we show a novel form of cell-to-cell communication based on adenosine triphosphate (ATP). ATP released by stimulated T cells induces P2X4/P2X7-mediated calcium waves in the neighboring lymphocytes. Our data obtained in lymph node slices suggest that, during T-cell priming, ATP acts as a paracrine messenger to reduce the motility of lymphocytes and that this may be relevant to allow optimal tissue scanning by T cells.
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Affiliation(s)
- Chiuhui Mary Wang
- Humanitas Clinical and Research Center, Rozzano, Italy Department of Translational Medicine, University of Milan, Rozzano, Italy
| | | | - Fabio Anselmi
- Humanitas Clinical and Research Center, Rozzano, Italy
| | | | - Antonella Viola
- Humanitas Clinical and Research Center, Rozzano, Italy Department of Translational Medicine, University of Milan, Rozzano, Italy
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22
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Burnstock G, Vaughn B, Robson SC. Purinergic signalling in the liver in health and disease. Purinergic Signal 2014; 10:51-70. [PMID: 24271096 PMCID: PMC3944046 DOI: 10.1007/s11302-013-9398-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/24/2013] [Indexed: 12/18/2022] Open
Abstract
Purinergic signalling is involved in both the physiology and pathophysiology of the liver. Hepatocytes, Kupffer cells, vascular endothelial cells and smooth muscle cells, stellate cells and cholangiocytes all express purinoceptor subtypes activated by adenosine, adenosine 5'-triphosphate, adenosine diphosphate, uridine 5'-triphosphate or UDP. Purinoceptors mediate bile secretion, glycogen and lipid metabolism and indirectly release of insulin. Mechanical stress results in release of ATP from hepatocytes and Kupffer cells and ATP is also released as a cotransmitter with noradrenaline from sympathetic nerves supplying the liver. Ecto-nucleotidases play important roles in the signalling process. Changes in purinergic signalling occur in vascular injury, inflammation, insulin resistance, hepatic fibrosis, cirrhosis, diabetes, hepatitis, liver regeneration following injury or transplantation and cancer. Purinergic therapeutic strategies for the treatment of these pathologies are being explored.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK,
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23
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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: 57] [Impact Index Per Article: 5.7] [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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24
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Amaya MJ, Nathanson MH. Calcium signaling and the secretory activity of bile duct epithelia. Cell Calcium 2014; 55:317-24. [PMID: 24612866 DOI: 10.1016/j.ceca.2014.02.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 02/03/2014] [Accepted: 02/04/2014] [Indexed: 12/20/2022]
Abstract
Cytosolic calcium (Cai(2+)) is a second messenger that is important for the regulation of secretion in many types of tissues. Bile duct epithelial cells, or cholangiocytes, are polarized epithelia that line the biliary tree in liver and are responsible for secretion of bicarbonate and other solutes into bile. Cai(2+) signaling plays an important role in the regulation of secretion by cholangiocytes, and this review discusses the machinery involved in the formation of Ca(2+) signals in cholangiocytes, along with the evidence that these signals regulate ductular secretion. Finally, this review discusses the evidence that impairments in cholangiocyte Ca(2+) signaling play a primary role in the pathogenesis of cholestatic disorders, in which hepatic bile secretion is impaired.
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Affiliation(s)
- Maria Jimena Amaya
- Section of Digestive Diseases, Department of Internal Medicine, Yale University, 333 Cedar Street, PO Box 208019, New Haven, CT 06520-8019, USA
| | - Michael H Nathanson
- Section of Digestive Diseases, Department of Internal Medicine, Yale University, 333 Cedar Street, PO Box 208019, New Haven, CT 06520-8019, USA.
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25
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Abstract
Bile is a unique and vital aqueous secretion of the liver that is formed by the hepatocyte and modified down stream by absorptive and secretory properties of the bile duct epithelium. Approximately 5% of bile consists of organic and inorganic solutes of considerable complexity. The bile-secretory unit consists of a canalicular network which is formed by the apical membrane of adjacent hepatocytes and sealed by tight junctions. The bile canaliculi (∼1 μm in diameter) conduct the flow of bile countercurrent to the direction of portal blood flow and connect with the canal of Hering and bile ducts which progressively increase in diameter and complexity prior to the entry of bile into the gallbladder, common bile duct, and intestine. Canalicular bile secretion is determined by both bile salt-dependent and independent transport systems which are localized at the apical membrane of the hepatocyte and largely consist of a series of adenosine triphosphate-binding cassette transport proteins that function as export pumps for bile salts and other organic solutes. These transporters create osmotic gradients within the bile canalicular lumen that provide the driving force for movement of fluid into the lumen via aquaporins. Species vary with respect to the relative amounts of bile salt-dependent and independent canalicular flow and cholangiocyte secretion which is highly regulated by hormones, second messengers, and signal transduction pathways. Most determinants of bile secretion are now characterized at the molecular level in animal models and in man. Genetic mutations serve to illuminate many of their functions.
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Affiliation(s)
- James L Boyer
- Department of Medicine and Liver Center, Yale University School of Medicine, New Haven, Connecticut, USA.
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26
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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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27
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Tabibian JH, Masyuk AI, Masyuk TV, O'Hara SP, LaRusso NF. Physiology of cholangiocytes. Compr Physiol 2013; 3:541-65. [PMID: 23720296 DOI: 10.1002/cphy.c120019] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cholangiocytes are epithelial cells that line the intra- and extrahepatic ducts of the biliary tree. The main physiologic function of cholangiocytes is modification of hepatocyte-derived bile, an intricate process regulated by hormones, peptides, nucleotides, neurotransmitters, and other molecules through intracellular signaling pathways and cascades. The mechanisms and regulation of bile modification are reviewed herein.
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28
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A novel hypothesis for an alkaline phosphatase 'rescue' mechanism in the hepatic acute phase immune response. Biochim Biophys Acta Mol Basis Dis 2013; 1832:2044-56. [PMID: 23899605 DOI: 10.1016/j.bbadis.2013.07.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 07/10/2013] [Accepted: 07/22/2013] [Indexed: 12/24/2022]
Abstract
The liver isoform of the enzyme alkaline phosphatase (AP) has been used classically as a serum biomarker for hepatic disease states such as hepatitis, steatosis, cirrhosis, drug-induced liver injury, and hepatocellular carcinoma. Recent studies have demonstrated a more general anti-inflammatory role for AP, as it is capable of dephosphorylating potentially deleterious molecules such as nucleotide phosphates, the pathogenic endotoxin lipopolysaccharide (LPS), and the contact clotting pathway activator polyphosphate (polyP), thereby reducing inflammation and coagulopathy systemically. Yet the mechanism underlying the observed increase in liver AP levels in circulation during inflammatory insults is largely unknown. This paper hypothesizes an immunological role for AP in the liver and the potential of this system for damping generalized inflammation along with a wide range of ancillary pathologies. Based on the provided framework, a mechanism is proposed in which AP undergoes transcytosis in hepatocytes from the canalicular membrane to the sinusoidal membrane during inflammation and the enzyme's expression is upregulated as a result. Through a tightly controlled, nucleotide-stimulated negative feedback process, AP is transported in this model as an immune complex with immunoglobulin G by the asialoglycoprotein receptor through the cell and secreted into the serum, likely using the receptor's State 1 pathway. The subsequent dephosphorylation of inflammatory stimuli by AP and uptake of the circulating immune complex by endothelial cells and macrophages may lead to decreased inflammation and coagulopathy while providing an early upstream signal for the induction of a number of anti-inflammatory gene products, including AP itself.
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Abu Khamidakh A, Juuti-Uusitalo K, Larsson K, Skottman H, Hyttinen J. Intercellular Ca2+ wave propagation in human retinal pigment epithelium cells induced by mechanical stimulation. Exp Eye Res 2013; 108:129-39. [DOI: 10.1016/j.exer.2013.01.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 01/10/2013] [Accepted: 01/14/2013] [Indexed: 01/19/2023]
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30
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Amaral SS, Oliveira AG, Marques PE, Quintão JLD, Pires DA, Resende RR, Sousa BR, Melgaço JG, Pinto MA, Russo RC, Gomes AKC, Andrade LM, Zanin RF, Pereira RVS, Bonorino C, Soriani FM, Lima CX, Cara DC, Teixeira MM, Leite MF, Menezes GB. Altered responsiveness to extracellular ATP enhances acetaminophen hepatotoxicity. Cell Commun Signal 2013; 11:10. [PMID: 23384127 PMCID: PMC3608937 DOI: 10.1186/1478-811x-11-10] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 01/26/2013] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Adenosine triphosphate (ATP) is secreted from hepatocytes under physiological conditions and plays an important role in liver biology through the activation of P2 receptors. Conversely, higher extracellular ATP concentrations, as observed during necrosis, trigger inflammatory responses that contribute to the progression of liver injury. Impaired calcium (Ca2+) homeostasis is a hallmark of acetaminophen (APAP)-induced hepatotoxicity, and since ATP induces mobilization of the intracellular Ca2+ stocks, we evaluated if the release of ATP during APAP-induced necrosis could directly contribute to hepatocyte death. RESULTS APAP overdose resulted in liver necrosis, massive neutrophil infiltration and large non-perfused areas, as well as remote lung inflammation. In the liver, these effects were significantly abrogated after ATP metabolism by apyrase or P2X receptors blockage, but none of the treatments prevented remote lung inflammation, suggesting a confined local contribution of purinergic signaling into liver environment. In vitro, APAP administration to primary mouse hepatocytes and also HepG2 cells caused cell death in a dose-dependent manner. Interestingly, exposure of HepG2 cells to APAP elicited significant release of ATP to the supernatant in levels that were high enough to promote direct cytotoxicity to healthy primary hepatocytes or HepG2 cells. In agreement to our in vivo results, apyrase treatment or blockage of P2 receptors reduced APAP cytotoxicity. Likewise, ATP exposure caused significant higher intracellular Ca2+ signal in APAP-treated primary hepatocytes, which was reproduced in HepG2 cells. Quantitative real time PCR showed that APAP-challenged HepG2 cells expressed higher levels of several purinergic receptors, which may explain the hypersensitivity to extracellular ATP. This phenotype was confirmed in humans analyzing liver biopsies from patients diagnosed with acute hepatic failure. CONCLUSION We suggest that under pathological conditions, ATP may act not only an immune system activator, but also as a paracrine direct cytotoxic DAMP through the dysregulation of Ca2+ homeostasis.
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Affiliation(s)
- Sylvia S Amaral
- Laboratório de Imunobiofotônica, Departamento de Morfologia, UFMG, Belo Horizonte, MG, Brazil.
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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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Wang N, De Bock M, Decrock E, Bol M, Gadicherla A, Vinken M, Rogiers V, Bukauskas FF, Bultynck G, Leybaert L. Paracrine signaling through plasma membrane hemichannels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:35-50. [PMID: 22796188 DOI: 10.1016/j.bbamem.2012.07.002] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 06/29/2012] [Accepted: 07/06/2012] [Indexed: 12/24/2022]
Abstract
Plasma membrane hemichannels composed of connexin (Cx) proteins are essential components of gap junction channels but accumulating evidence suggests functions of hemichannels beyond the communication provided by junctional channels. Hemichannels not incorporated into gap junctions, called unapposed hemichannels, can open in response to a variety of signals, electrical and chemical, thereby forming a conduit between the cell's interior and the extracellular milieu. Open hemichannels allow the bidirectional passage of ions and small metabolic or signaling molecules of below 1-2kDa molecular weight. In addition to connexins, hemichannels can also be formed by pannexin (Panx) proteins and current evidence suggests that Cx26, Cx32, Cx36, Cx43 and Panx1, form hemichannels that allow the diffusive release of paracrine messengers. In particular, the case is strong for ATP but substantial evidence is also available for other messengers like glutamate and prostaglandins or metabolic substances like NAD(+) or glutathione. While this field is clearly in expansion, evidence is still lacking at essential points of the paracrine signaling cascade that includes not only messenger release, but also downstream receptor signaling and consequent functional effects. The data available at this moment largely derives from in vitro experiments and still suffers from the difficulty of separating the functions of connexin-based hemichannels from gap junctions and from pannexin hemichannels. However, messengers like ATP or glutamate have universal roles in the body and further defining the contribution of hemichannels as a possible release pathway is expected to open novel avenues for better understanding their contribution to a variety of physiological and pathological processes. This article is part of a Special Issue entitled: The Communicating junctions, roles and dysfunctions.
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Affiliation(s)
- Nan Wang
- Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
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Abshagen K, Eipel C, Vollmar B. A critical appraisal of the hemodynamic signal driving liver regeneration. Langenbecks Arch Surg 2012; 397:579-90. [PMID: 22311102 DOI: 10.1007/s00423-012-0913-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 01/20/2012] [Indexed: 12/25/2022]
Abstract
BACKGROUND Many aspects of the signaling mechanisms involved in the initiation of hepatic regeneration are under current investigation. Nevertheless, the actual mechanisms switching liver regeneration on and off are still unknown. Hemodynamic changes in the liver following partial hepatectomy have been suggested to be a primary stimulus in triggering liver regeneration. Most of the new knowledge about the impact of hemodynamic changes on liver regeneration is both conceptually important and directly relevant to clinical problems. PURPOSE The purpose of this review is therefore to exclusively address the hemodynamic signal driving the liver regeneration process.
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Affiliation(s)
- Kerstin Abshagen
- Institute for Experimental Surgery, University of Rostock, 18055 Rostock, Germany.
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Fausther M, Gonzales E, Dranoff JA. Role of purinergic P2X receptors in the control of liver homeostasis. ACTA ACUST UNITED AC 2012; 1:341-348. [PMID: 22662313 DOI: 10.1002/wmts.32] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
It is now accepted that extracellular ATP and other nucleotides are potent signaling molecules, akin to neurotransmitters, hormones and lipid mediators. In the liver, several clues support a significant role for extracellular ATP-induced signaling pathways in the control of tissue homeostasis. First, ATP and other nucleotides are physiologically detected in extracellular fluids within the liver, including sinusoidal blood and intraductular bile, in various mammalian species including human and rodents. Moreover, finely tuned mechanisms of ATP release by different liver cell types have been described, under physiological cellular changes. In addition, most hepatic cells constitutively express, at the membrane level, several ATP-metabolizing ectoenzymes and ATP-sensitive receptors that modulate and transduce these mediator signals respectively. Finally, hepatic cells also express numerous membrane transporters that actively contribute to purinergic salvage pathways. Once released in the extracellular medium, unmetabolised ATP molecules can bind to purinergic P2X and P2Y receptors, and subsequently trigger various intracellular signal transduction pathways collectively referred to as purinergic signaling. In the liver, purinergic signaling has been shown to regulate key basic cellular functions, such as glucose/lipid metabolism, protein synthesis and ionic secretion, and homeostatic processes, such as cell cycle, inflammatory response and immunity. Whilst the functional relevance of P2Y receptors in liver physiology has been well documented, limited information is available regarding the potential role of hepatic P2X receptors in the modulation of liver homeostasis.
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Affiliation(s)
- Michel Fausther
- Division of Gastroenterology & Hepatology, Department, of Internal Medicine, College of Medicine, University of Arkansas for, Medical Sciences, Little Rock, AR, USA
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The hepatitis B virus X protein elevates cytosolic calcium signals by modulating mitochondrial calcium uptake. J Virol 2011; 86:313-27. [PMID: 22031934 DOI: 10.1128/jvi.06442-11] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Chronic hepatitis B virus (HBV) infections are associated with the development of hepatocellular carcinoma (HCC). The HBV X protein (HBx) is thought to play an important role in the development of HBV-associated HCC. One fundamental HBx function is elevation of cytosolic calcium signals; this HBx activity has been linked to HBx stimulation of cell proliferation and transcription pathways, as well as HBV replication. Exactly how HBx elevates cytosolic calcium signals is not clear. The studies described here show that HBx stimulates calcium entry into cells, resulting in an increased plateau level of inositol 1,4,5-triphosphate (IP3)-linked calcium signals. This increased calcium plateau can be inhibited by blocking mitochondrial calcium uptake and store-operated calcium entry (SOCE). Blocking SOCE also reduced HBV replication. Finally, these studies also demonstrate that there is increased mitochondrial calcium uptake in HBx-expressing cells. Cumulatively, these studies suggest that HBx can increase mitochondrial calcium uptake and promote increased SOCE to sustain higher cytosolic calcium and stimulate HBV replication.
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Bao J, Shi Y, Sun H, Yin X, Yang R, Li L, Chen X, Bu H. Construction of a portal implantable functional tissue-engineered liver using perfusion-decellularized matrix and hepatocytes in rats. Cell Transplant 2010; 20:753-66. [PMID: 21054928 DOI: 10.3727/096368910x536572] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Innovative cell-based therapies, including hepatic tissue engineering following hepatocyte transplantation, are considered as theoretical alternatives to liver transplant or for partial replacement of liver function in patients. However, recent progress in hepatic tissue engineering has been hampered by low initial hepatocyte engraftment and insufficient blood supply in vivo. We developed an intact 3D scaffold of an extracellular matrix (ECM) derived from a decellularized liver lobe, with layer-by-layer (LbL) heparin deposition to avoid thrombosis, which we repopulated with hepatocytes and successfully implanted as a tissue-engineered liver (TEL) into the portal system. The TEL provided sufficient volume for transplantation of cell numbers representing up to 10% of whole-liver equivalents and was perfused by portal vein blood. Treatment of extended hepatectomized rats with a TEL improved liver function and prolonged survival; mean lifespan was extended from 16 to 72 h. At 72 h postoperation, the TEL sustained functional and viable hepatocytes. In conclusion, we propose the TEL as a state-of-the-art substitute for whole-liver transplantation and as a proof of concept for the technology that will eventually allow for the transplantation of a reconstituted liver.
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Affiliation(s)
- Ji Bao
- Key Laboratory of Transplant Engineering and Immunology, West China Hospital, Sichuan University, Chengdu, China
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37
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Beuers U, Hohenester S, de Buy Wenniger LJM, Kremer AE, Jansen PLM, Elferink RPJO. The biliary HCO(3)(-) umbrella: a unifying hypothesis on pathogenetic and therapeutic aspects of fibrosing cholangiopathies. Hepatology 2010; 52:1489-96. [PMID: 20721884 DOI: 10.1002/hep.23810] [Citation(s) in RCA: 248] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This review focuses on the hypothesis that biliary HCO(3)(-) secretion in humans serves to maintain an alkaline pH near the apical surface of hepatocytes and cholangiocytes to prevent the uncontrolled membrane permeation of protonated glycine-conjugated bile acids. Functional impairment of this biliary HCO(3)(-) umbrella or its regulation may lead to enhanced vulnerability of cholangiocytes and periportal hepatocytes toward the attack of apolar hydrophobic bile acids. An intact interplay of hepatocellular and cholangiocellular adenosine triphosphate (ATP) secretion, ATP/P2Y- and bile salt/TGR5-mediated Cl(-)/ HCO(3)(-) exchange and HCO(3)(-) secretion, and alkaline phosphatase-mediated ATP breakdown may guarantee a stable biliary HCO(3)(-) umbrella under physiological conditions. Genetic and acquired functional defects leading to destabilization of the biliary HCO(3)(-) umbrella may contribute to development and progression of various forms of fibrosing/sclerosing cholangitis.
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Affiliation(s)
- Ulrich Beuers
- Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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Dolovcak S, Waldrop SL, Fitz JG, Kilic G. Copper inhibits P2Y(2)-dependent Ca(2+) signaling through the effects on thapsigargin-sensitive Ca(2+) stores in HTC hepatoma cells. Biochem Biophys Res Commun 2010; 397:493-8. [PMID: 20515656 DOI: 10.1016/j.bbrc.2010.05.141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Accepted: 05/27/2010] [Indexed: 01/08/2023]
Abstract
Purinergic P2Y(2) G-protein coupled receptors play a key role in the regulation of hepatic Ca(2+) signaling by extracellular ATP. The concentration of copper in serum is about 20muM. Since copper accumulates in the liver in certain disease states, the purpose of these studies was to assess the effects of copper on P2Y(2) receptors in a model liver cell line. Exposure to a P2Y(2) agonist UTP increased [Ca(2+)](i) by stimulating Ca(2+) release from thapsigargin-sensitive Ca(2+) stores. Pretreatment of HTC cells for several minutes with copper did not affect cell viability, but potently inhibited increases in [Ca(2+)](i) evoked by UTP and thapsigargin. During this pretreatment, copper was not transported into the cytosol, and inhibited P2Y(2) receptors in a concentration-dependent manner with the IC(50) of about 15muM. These results suggest that copper inhibits P2Y(2) receptors through the effects on thapsigargin-sensitive Ca(2+) stores by acting from an extracellular side. Further experiments indicated that these effect of copper may lead to inhibition of regulatory volume decrease (RVD) evoked by hypotonic solution. Thus, copper may contribute to defective regulation of purinergic signaling and liver cell volume in diseases associated with the increased serum copper concentration.
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Affiliation(s)
- Svjetlana Dolovcak
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9151, USA
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MRP transporters as membrane machinery in the bradykinin-inducible export of ATP. Naunyn Schmiedebergs Arch Pharmacol 2010; 381:315-20. [PMID: 20135098 DOI: 10.1007/s00210-009-0490-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Accepted: 12/23/2009] [Indexed: 10/19/2022]
Abstract
Adenosine triphosphate (ATP) plays the role of an autocrine/paracrine signal molecule in a variety of cells. So far, however, the membrane machinery in the export of intracellular ATP remains poorly understood. Activation of B2-receptor with bradykinin-induced massive release of ATP from cultured taenia coli smooth muscle cells. The evoked release of ATP was unaffected by gap junction hemichannel blockers, such as 18alpha-glycyrrhetinic acid and Gap 26. Furthermore, the cystic fibrosis transmembrane regulator (CFTR) coupled Cl(-) channel blockers, CFTR(inh)172, 5-nitro-2-(3-phenylpropylamino)-benzoic acid, Gd3(+) and glibenclamide, failed to suppress the export of ATP by bradykinin. On the other, the evoked release of ATP was greatly reduced by multidrug resistance protein (MRP) transporter inhibitors, MK-571, indomethacin, and benzbromarone. From western blotting analysis, blots of MRP 1 protein only, but not MRP 2 and MRP 3 protein, appeared at 190 kD. However, the MRP 1 protein expression was not enhanced after loading with 1 muM bradykinin for 5 min. Likewise, niflumic acid and fulfenamic acid, Ca2(+)-activated Cl(-) channel blockers, largely abated the evoked release of ATP. The possibility that the MRP transporter system couples with Ca2(+)-activated Cl(-) channel activities is discussed here. These findings suggest that MRP transporters, probably MRP 1, unlike CFTR-Cl(-) channels and gap junction hemichannels, may contribute as membrane machinery to the export of ATP induced by G-protein-coupled receptor stimulation.
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40
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Feranchak AP, Lewis MA, Kresge C, Sathe M, Bugde A, Luby-Phelps K, Antich PP, Fitz JG. Initiation of purinergic signaling by exocytosis of ATP-containing vesicles in liver epithelium. J Biol Chem 2010; 285:8138-47. [PMID: 20071341 DOI: 10.1074/jbc.m109.065482] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Extracellular ATP represents an important autocrine/paracrine signaling molecule within the liver. The mechanisms responsible for ATP release are unknown, and alternative pathways have been proposed, including either conductive ATP movement through channels or exocytosis of ATP-enriched vesicles, although direct evidence from liver cells has been lacking. Utilizing dynamic imaging modalities (confocal and total internal reflection fluorescence microscopy and luminescence detection utilizing a high sensitivity CCD camera) at different scales, including confluent cell populations, single cells, and the intracellular submembrane space, we have demonstrated in a model liver cell line that (i) ATP release is not uniform but reflects point source release by a defined subset of cells; (ii) ATP within cells is localized to discrete zones of high intensity that are approximately 1 mum in diameter, suggesting a vesicular localization; (iii) these vesicles originate from a bafilomycin A(1)-sensitive pool, are depleted by hypotonic exposure, and are not rapidly replenished from recycling of endocytic vesicles; and (iv) exocytosis of vesicles in response to cell volume changes depends upon a complex series of signaling events that requires intact microtubules as well as phosphoinositide 3-kinase and protein kinase C. Collectively, these findings are most consistent with an essential role for exocytosis in regulated release of ATP and initiation of purinergic signaling in liver cells.
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Affiliation(s)
- Andrew P Feranchak
- Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-9030, USA.
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41
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Corriden R, Insel PA. Basal release of ATP: an autocrine-paracrine mechanism for cell regulation. Sci Signal 2010; 3:re1. [PMID: 20068232 DOI: 10.1126/scisignal.3104re1] [Citation(s) in RCA: 263] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Cells release adenosine triphosphate (ATP), which activates plasma membrane-localized P2X and P2Y receptors and thereby modulates cellular function in an autocrine or paracrine manner. Release of ATP and the subsequent activation of P2 receptors help establish the basal level of activation (sometimes termed "the set point") for signal transduction pathways and regulate a wide array of responses that include tissue blood flow, ion transport, cell volume regulation, neuronal signaling, and host-pathogen interactions. Basal release and autocrine or paracrine responses to ATP are multifunctional, evolutionarily conserved, and provide an economical means for the modulation of cell, tissue, and organismal biology.
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Affiliation(s)
- Ross Corriden
- Departments of Pharmacology and Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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42
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P2 receptor-mediated signaling in mast cell biology. Purinergic Signal 2009; 6:3-17. [PMID: 19921464 DOI: 10.1007/s11302-009-9173-z] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 10/23/2009] [Indexed: 12/22/2022] Open
Abstract
Mast cells are widely recognized as effector cells of allergic inflammatory reactions. They contribute to the pathogenesis of different chronic inflammatory diseases, wound healing, fibrosis, thrombosis/fibrinolysis, and anti-tumor immune responses. In this paper, we summarized the role of P2X and P2Y receptors in mast cell activation and effector functions. Mast cells are an abundant source of ATP which is stored in their granules and secreted upon activation. We discuss the contribution of mast cells to the extracellular ATP release and to the maintenance of extracellular nucleotides pool. Recent publications highlight the importance of purinergic signaling for the pathogenesis of chronic airway inflammation. Therefore, the role of ATP and P2 receptors in allergic inflammation with focus on mast cells was analyzed. Finally, ATP functions as mast cell autocrine/paracrine factor and as messenger in intercellular communication between mast cells, nerves, and glia in the central nervous system.
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Crumm S, Cofan M, Juskeviciute E, Hoek JB. Adenine nucleotide changes in the remnant liver: An early signal for regeneration after partial hepatectomy. Hepatology 2008; 48:898-908. [PMID: 18697206 PMCID: PMC3348855 DOI: 10.1002/hep.22421] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
UNLABELLED Liver regeneration after partial hepatectomy (PHx) is orchestrated by multiple signals from cytokines and growth factors. We investigated whether increased energy demand on the remnant liver after PHx contributes to regenerative signals. Changes in the tissue's energy state were determined from adenine nucleotide levels. Adenosine triphosphate (ATP) levels in remnant livers decreased markedly and rapidly (to 48% of control by 30 seconds post-PHx) and remained significantly lower than those in sham-operated controls for 24 to 48 hours. The ATP decrease was not reflected in corresponding increases in adenosine diphosphate (ADP) and adenosine monophosphate (AMP), resulting in a marked decline in total adenine nucleotides (TAN). We found no evidence of mitochondrial damage or uncoupling of oxidative phosphorylation. Multiple lines of evidence indicated that the decline in TAN was not caused by increased energy demand, but by ATP release from the liver. The extent of ATP loss was identical after 30% or 70% PHx, whereas fasting or hyperglycemia, conditions that greatly alter energy demand for gluconeogenesis, affected the ATP/ADP decline but not the loss of TAN. Presurgical treatment with the alpha-adrenergic antagonist phentolamine completely prevented loss of TAN, although changes in ATP/ADP were still apparent. Importantly, phentolamine treatment inhibited early signaling events associated with the priming stages of liver regeneration and suppressed the expression of c-fos. Pretreatment with the purinergic receptor antagonist suramin also partly suppressed early regenerative signals and c-fos expression, but without preventing TAN loss. CONCLUSION The rapid loss of adenine nucleotides after PHx generates early stress signals that contribute to the onset of liver regeneration.
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Affiliation(s)
- Sara Crumm
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
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44
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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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Katsuragi T, Sato C, Usune S, Ueno S, Segawa M, Migita K. Caffeine-inducible ATP release is mediated by Ca2+-signal transducing system from the endoplasmic reticulum to mitochondria. Naunyn Schmiedebergs Arch Pharmacol 2008; 378:93-101. [PMID: 18446524 DOI: 10.1007/s00210-008-0292-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Accepted: 03/27/2008] [Indexed: 10/22/2022]
Abstract
Adenosine triphosphate (ATP) is released as an autocrine/paracrine signal from a variety of cells. The present study was undertaken to clarify the Ca2+-signal pathway involved in the caffeine-inducible release of ATP from cultured smooth muscle cells (SMC). The release of ATP induced by caffeine (3 mM) was almost completely inhibited by ryanodine and tetracaine, but not by 2-APB, thus being mediated by ryanodine receptors (RyR). The expression of messenger RNA from only RyR-2 was detected in the cells. Furthermore, the induced release was attenuated by mitochondrial inhibitors, rotenone and oligomycin and by Cl- channel blockers, niflumic acid, and 5-nitro-2-(3-phenylpropylamino)-benzoic acid. Increase in Ca2+-signals with fluo 4 and rhod-2 caused by caffeine were reduced by tetracaine and oligomycin plus carbonyl cyanide m-chlorophenylhydrazone, respectively. A close spatial relation between the endoplasmic reticulum (ER) and mitochondria was electromicroscopically observed in the SMC, supporting the existence of a Ca2+-signaling bridge on both the organelli. These results suggest that caffeine stimulates ryanodine receptor (RyR-2) and facilitates a Ca2+-signal transducing system from ER to mitochondria, and then, the signal appears to accelerate the ATP synthesis in mitochondria. In addition, the mitochondrial event may lead further cell signaling to the cell membrane and activates Cl- channels, resulting in the extracellular release of cytosolic ATP.
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Affiliation(s)
- Takeshi Katsuragi
- Department of Pharmacology, Fukuoka University, Fukuoka, 814-0180, Japan.
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Beldi G, Enjyoji K, Wu Y, Miller L, Banz Y, Sun X, Robson SC. The role of purinergic signaling in the liver and in transplantation: effects of extracellular nucleotides on hepatic graft vascular injury, rejection and metabolism. FRONT BIOSCI-LANDMRK 2008; 13:2588-603. [PMID: 17981736 DOI: 10.2741/2868] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Extracellular nucleotides (e.g. ATP, UTP, ADP) are released by activated endothelium, leukocytes and platelets within the injured vasculature and bind specific cell-surface type-2 purinergic (P2) receptors. This process drives vascular inflammation and thrombosis within grafted organs. Importantly, there are also vascular ectonucleotidases i.e. ectoenzymes that hydrolyze extracellular nucleotides in the blood to generate nucleosides (viz. adenosine). Endothelial cell NTPDase1/CD39 has been shown to critically modulate levels of circulating nucleotides. This process tends to limit the activation of platelet and leukocyte expressed P2 receptors and also generates adenosine to reverse inflammatory events. This vascular protective CD39 activity is rapidly inhibited by oxidative reactions, such as is observed with liver ischemia reperfusion injury. In this review, we chiefly address the impact of these signaling cascades following liver transplantation. Interestingly, the hepatic vasculature, hepatocytes and all non-parenchymal cell types express several components co-ordinating the purinergic signaling response. With hepatic and vascular dysfunction, we note heightened P2- expression and alterations in ectonucleotidase expression and function that may predispose to progression of disease. In addition to documented impacts upon the vasculature during engraftment, extracellular nucleotides also have direct influences upon liver function and bile flow (both under physiological and pathological states). We have recently shown that alterations in purinergic signaling mediated by altered CD39 expression have major impacts upon hepatic metabolism, repair mechanisms, regeneration and associated immune responses. Future clinical applications in transplantation might involve new therapeutic modalities using soluble recombinant forms of CD39, altering expression of this ectonucleotidase by drugs and/or using small molecules to inhibit deleterious P2-mediated signaling while augmenting beneficial adenosine-mediated effects within the transplanted liver.
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Affiliation(s)
- Guido Beldi
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard University, Boston, MA 02215, USA
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Fiorotto R, Spirlì C, Fabris L, Cadamuro M, Okolicsanyi L, Strazzabosco M. Ursodeoxycholic acid stimulates cholangiocyte fluid secretion in mice via CFTR-dependent ATP secretion. Gastroenterology 2007; 133:1603-13. [PMID: 17983806 DOI: 10.1053/j.gastro.2007.08.071] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2006] [Accepted: 07/26/2007] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Cholangiopathies are characterized by impaired cholangiocyte secretion. Ursodeoxycholic acid (UDCA) is widely used for cholangiopathy treatment, but its effects on cholangiocyte secretory functions remain unclear and are the subject of this study. METHODS Polarized mouse cholangiocytes in tubular (isolated bile-duct units [IBDU]) or monolayer configuration were obtained from wild-type (WT) and B6-129-Cftr(tm1Kth) and Cftr(tm1Unc) mice that are defective in CFTR, an adenosine 3',5'-cyclic monophosphate (cAMP)-stimulated Cl(-) channel expressed in cholangiocytes. Fluid secretion was assessed by video-optical planimetry, Cl(-) and Ca(2+) efflux by microfluorimetry (6-methoxy-N-ethylquinolinium chloride, fura-2, and fluo-4), adenosine triphosphate (ATP) secretion by luciferin-luciferase assay, and protein kinase C (PKC) by Western blot. RESULTS UDCA stimulated fluid secretion and Cl(-) efflux in WT-IBDU but not in CFTR-KO-IBDU or in WT-IBDU exposed to CFTR inhibitors. UDCA did not affect intracellular cAMP levels but increased [Ca(2+)]i in WT and not in CFTR-KO cholangiocytes. UDCA stimulated apical ATP secretion in WT but not in CFTR-KO cholangiocytes. UDCA-stimulated [Ca(2+)]i increase was inhibited by suramin, a purinergic 2Y-receptor inhibitor. UDCA stimulated the translocation of PKC-alpha and PKC-epsilon to the plasma membrane. UDCA-stimulated secretion was inhibited by 2-bis(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid and by phospholipase C and PKC inhibitors. UDCA increased ATP output in isolated perfused livers from WT but not from CFTR-KO mice. CONCLUSIONS Our data indicate that UDCA stimulates a CFTR-dependent apical ATP release in cholangiocytes. Secreted ATP activates purinergic 2Y receptors, and, through [Ca(2+)]i increase and PKC activation stimulates Cl(-) efflux and fluid secretion. These data support the concept that CFTR plays a role in modulating purinergic signaling in secretory epithelia and suggest a novel mechanism explaining the choleretic effect of UDCA.
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Affiliation(s)
- Romina Fiorotto
- Department of Internal Medicine, Section of Digestive Diseases, Yale University School of Medicine and Liver Center, New Haven, Connecticut, USA
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Minagawa N, Nagata J, Shibao K, Masyuk AI, Gomes DA, Rodrigues MA, LeSage G, Akiba Y, Kaunitz JD, Ehrlich BE, LaRusso NF, Nathanson MH. Cyclic AMP regulates bicarbonate secretion in cholangiocytes through release of ATP into bile. Gastroenterology 2007; 133:1592-602. [PMID: 17916355 PMCID: PMC2128713 DOI: 10.1053/j.gastro.2007.08.020] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2006] [Accepted: 07/02/2007] [Indexed: 01/07/2023]
Abstract
BACKGROUND & AIMS Bicarbonate secretion is a primary function of cholangiocytes. Either adenosine 3',5'-cyclic monophosphate (cAMP) or cytosolic Ca(2+) can mediate bicarbonate secretion, but these are thought to act through separate pathways. We examined the role of the inositol 1,4,5-trisphosphate receptor (InsP3R) in mediating bicarbonate secretion because this is the only intracellular Ca(2+) release channel in cholangiocytes. METHODS Intrahepatic bile duct units (IBDUs) were microdissected from rat liver then luminal pH was examined by confocal microscopy during IBDU microperfusion. Cyclic AMP was increased using forskolin or secretin, and Ca(2+) was increased using acetylcholine (ACh) or adenosine triphosphate (ATP). Apyrase was used to hydrolyze extracellular ATP, and suramin was used to block apical P2Y ATP receptors. In selected experiments, IBDUs were pretreated with short interfering RNA (siRNA) to silence expression of specific InsP3R isoforms. RESULTS Both cAMP and Ca(2+) agonists increased luminal pH. The effect of ACh on luminal pH was reduced by siRNA for basolateral (types I and II) but not apical (type III) InsP3R isoforms. The effect of forskolin on luminal pH was reduced by a cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor and by siRNA for the type III InsP3R. Luminal apyrase or suramin blocked the effects of forskolin but not ACh on luminal pH. CONCLUSIONS Cyclic AMP-induced ductular bicarbonate secretion depends on an autocrine signaling pathway that involves CFTR, apical release of ATP, stimulation of apical nucleotide receptors, and then activation of apical, type III InsP3Rs. The primary role of CFTR in bile duct secretion may be to regulate secretion of ATP rather than to secrete chloride and/or bicarbonate.
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Affiliation(s)
- Noritaka Minagawa
- Department of Medicine, Yale University School of Medicine, New Haven, CT, Department of Surgery 1, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Jun Nagata
- Department of Medicine, Yale University School of Medicine, New Haven, CT, Department of Surgery 1, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Kazunori Shibao
- Department of Medicine, Yale University School of Medicine, New Haven, CT, Department of Surgery 1, University of Occupational and Environmental Health, Kitakyushu, Japan
| | | | - Dawidson A. Gomes
- Department of Medicine, Yale University School of Medicine, New Haven, CT
| | | | - Gene LeSage
- Department of Medicine, University of Texas, Houston, TX
| | - Yasutada Akiba
- Department of Medicine, University of California, Los Angeles, CA
| | | | - Barbara E. Ehrlich
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT
| | | | - Michael H. Nathanson
- Department of Medicine, Yale University School of Medicine, New Haven, CT,7Address for correspondence: Michael H. Nathanson, Digestive Diseases, Room TAC S241D, Yale University School of Medicine, New Haven, CT 06520-8019, Phone 203-785-7312, FAX 203-785-4306,
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Green AK, Stratton RC, Squires PE, Simpson AWM. Atrial natriuretic peptide attenuates elevations in Ca2+ and protects hepatocytes by stimulating net plasma membrane Ca2+ efflux. J Biol Chem 2007; 282:34542-54. [PMID: 17893148 DOI: 10.1074/jbc.m707115200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Elevations in intracellular Ca(2+) concentration and calpain activity are common early events in cellular injury, including that of hepatocytes. Atrial natriuretic peptide is a circulating hormone that has been shown to be hepatoprotective. The aim of this study was to examine the effects of atrial natriuretic peptide on potentially harmful elevations in cytosolic free Ca(2+) and calpain activity induced by extracellular ATP in rat hepatocytes. We show that atrial natriuretic peptide, through protein kinase G, attenuated both the amplitude and duration of ATP-induced cytosolic Ca(2+) rises in single hepatocytes. Atrial natriuretic peptide also prevented stimulation of calpain activity by ATP, taurolithocholate, or Ca(2+) mobilization by thapsigargin and ionomycin. We therefore investigated the cellular Ca(2+) handling mechanisms through which ANP attenuates this sustained elevation in cytosolic Ca(2+). We show that atrial natriuretic peptide does not modulate the release from or re-uptake of Ca(2+) into intracellular stores but, through protein kinase G, both stimulates plasma membrane Ca(2+) efflux from and inhibits ATP-stimulated Ca(2+) influx into hepatocytes. These findings suggest that stimulation of net plasma membrane Ca(2+) efflux (to which both Ca(2+) efflux stimulation and Ca(2+) influx inhibition contribute) is the key process through which atrial natriuretic peptide attenuates elevations in cytosolic Ca(2+) and calpain activity. Moreover we propose that plasma membrane Ca(2+) efflux is a valuable, previously undiscovered, mechanism through which atrial natriuretic peptide protects rat hepatocytes, and perhaps other cell types, against Ca(2+)-dependent injury.
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Affiliation(s)
- Anne K Green
- Department of Biological Sciences, The University of Warwick, Gibbet Hill Road, Coventry, UK.
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Zhao Y, Migita K, Sato C, Usune S, Iwamoto T, Katsuragi T. Endoplasmic reticulum is a key organella in bradykinin-triggered ATP release from cultured smooth muscle cells. J Pharmacol Sci 2007; 105:57-65. [PMID: 17827868 DOI: 10.1254/jphs.fp0070865] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
ATP has broad functions as an autocrine/paracrine molecule. The mode of ATP release and its intracellular source, however, are little understood. Here we show that bradykinin via B(2)-receptor stimulation induces the extracellular release of ATP via the inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)]-signaling pathway in cultured taenia coli smooth muscle cells. It was found that bradykinin also increased the production of Ins(1,4,5)P(3) and 2-APB-inhibitable [Ca(2+)](i). The evoked release of ATP was suppressed by the Ca(2+)-channel blockers, nifedipine, and verapamil. Moreover, the extracellular release of ATP was elicited by photoliberation of Ins(1,4,5)P(3). Bradykinin caused a quick and transient accumulation of intracellular ATP from cells treated with 1% perchloric acid solution (PCA), but not with the cell lysis buffer. Peak accumulation was prevented by 2-APB and thapsigargin, but not by nifedipine or verapamil, inhibitors of extracellular release of ATP. These findings suggest that bradykinin elicits the extracellular release of ATP that is mediated by the Ins(1,4,5)P(3)-induced Ca(2+) signaling and, finally, leads to a Ca(2+)-dependent export of ATP from the cells. Furthermore, the bradykinin-induced transient accumulation of ATP in the cells treated with PCA may imply a possible release of ATP from the endoplasmic reticulum.
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Affiliation(s)
- Yumei Zhao
- Department of Pharmacology, School of Medicine, Fukuoka University, Japan
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