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Holeček M. Aspartate-glutamate carrier 2 (citrin): a role in glucose and amino acid metabolism in the liver. BMB Rep 2023; 56:385-391. [PMID: 37254569 PMCID: PMC10390287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/19/2023] [Accepted: 05/29/2023] [Indexed: 06/01/2023] Open
Abstract
Aspartate-glutamate carrier 2 (AGC2, citrin) is a mitochondrial carrier expressed in the liver that transports aspartate from mitochondria into the cytosol in exchange for glutamate. The AGC2 is the main component of the malate-aspartate shuttle (MAS) that ensures indirect transport of NADH produced in the cytosol during glycolysis, lactate oxidation to pyruvate, and ethanol oxidation to acetaldehyde into mitochondria. Through MAS, AGC2 is necessary to maintain intracellular redox balance, mitochondrial respiration, and ATP synthesis. Through elevated cytosolic Ca2+ level, the AGC2 is stimulated by catecholamines and glucagon during starvation, exercise, and muscle wasting disorders. In these conditions, AGC2 increases aspartate input to the urea cycle, where aspartate is a source of one of two nitrogen atoms in the urea molecule (the other is ammonia), and a substrate for the synthesis of fumarate that is gradually converted to oxaloacetate, the starting substrate for gluconeogenesis. Furthermore, aspartate is a substrate for the synthesis of asparagine, nucleotides, and proteins. It is concluded that AGC2 plays a fundamental role in the compartmentalization of aspartate and glutamate metabolism and linkage of the reactions of MAS, glycolysis, gluconeogenesis, amino acid catabolism, urea cycle, protein synthesis, and cell proliferation. Targeting of AGC genes may represent a new therapeutic strategy to fight cancer. [BMB Reports 2023; 56(7): 385-391].
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Affiliation(s)
- Milan Holeček
- Department of Physiology, Faculty of Medicine, Charles University, Hradec Králové 500 03, Czech Republic
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2
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Holeček M. Aspartate-glutamate carrier 2 (citrin): a role in glucose and amino acid metabolism in the liver. BMB Rep 2023; 56:385-391. [PMID: 37254569 PMCID: PMC10390287 DOI: 10.5483/bmbrep.2023-0052] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/19/2023] [Accepted: 05/29/2023] [Indexed: 09/29/2023] Open
Abstract
Aspartate-glutamate carrier 2 (AGC2, citrin) is a mitochondrial carrier expressed in the liver that transports aspartate from mitochondria into the cytosol in exchange for glutamate. The AGC2 is the main component of the malate-aspartate shuttle (MAS) that ensures indirect transport of NADH produced in the cytosol during glycolysis, lactate oxidation to pyruvate, and ethanol oxidation to acetaldehyde into mitochondria. Through MAS, AGC2 is necessary to maintain intracellular redox balance, mitochondrial respiration, and ATP synthesis. Through elevated cytosolic Ca2+ level, the AGC2 is stimulated by catecholamines and glucagon during starvation, exercise, and muscle wasting disorders. In these conditions, AGC2 increases aspartate input to the urea cycle, where aspartate is a source of one of two nitrogen atoms in the urea molecule (the other is ammonia), and a substrate for the synthesis of fumarate that is gradually converted to oxaloacetate, the starting substrate for gluconeogenesis. Furthermore, aspartate is a substrate for the synthesis of asparagine, nucleotides, and proteins. It is concluded that AGC2 plays a fundamental role in the compartmentalization of aspartate and glutamate metabolism and linkage of the reactions of MAS, glycolysis, gluconeogenesis, amino acid catabolism, urea cycle, protein synthesis, and cell proliferation. Targeting of AGC genes may represent a new therapeutic strategy to fight cancer. [BMB Reports 2023; 56(7): 385-391].
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Affiliation(s)
- Milan Holeček
- Department of Physiology, Faculty of Medicine, Charles University, Hradec Králové 500 03, Czech Republic
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β 2-adrenergic receptor promotes liver regeneration partially through crosstalk with c-met. Cell Death Dis 2022; 13:571. [PMID: 35760785 PMCID: PMC9237079 DOI: 10.1038/s41419-022-04998-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 06/01/2022] [Accepted: 06/07/2022] [Indexed: 01/21/2023]
Abstract
The β2-adrenergic receptor (β2AR) is a G protein-coupled receptor (GPCR) that mediates the majority of cellular responses to external stimuli. Aberrant expression of β2AR results in various pathophysiological disorders, including tumorigenesis, but little is known about its role in liver regeneration. This study aims to investigate the impact and the underlying mechanism of β2AR in liver regeneration. Here, we found that β2AR was upregulated during liver regeneration induced by 70% PH. Deletion of β2AR in mice resulted in 62% mortality 2 days post-PH, decreased proliferative marker expression and impaired liver function throughout regeneration. Moreover, AAV8-mediated overexpression of β2AR in hepatocytes accelerated the regeneration process and increased target gene expression. Mechanistically, β2AR recruited G-protein-coupled receptor kinase 2 (GRK2) to the membrane and then formed a complex with c-met to transactivate c-met signaling, which triggered downstream extracellular regulated protein kinase (ERK) signaling activation and nuclear translocation. Inhibition of c-met with SU11274 or ERK with U0126 decreased β2AR overexpression-induced hepatocyte proliferation. Our findings revealed that β2AR might act as a critical mediator regulating liver regeneration by crosstalk with c-met and activation of ERK signaling.
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Lemos FDO, Florentino RM, Lima Filho ACM, Santos MLD, Leite MF. Inositol 1,4,5-trisphosphate receptor in the liver: Expression and function. World J Gastroenterol 2019; 25:6483-6494. [PMID: 31802829 PMCID: PMC6886013 DOI: 10.3748/wjg.v25.i44.6483] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 10/22/2019] [Accepted: 11/13/2019] [Indexed: 02/06/2023] Open
Abstract
The liver is a complex organ that performs several functions to maintain homeostasis. These functions are modulated by calcium, a second messenger that regulates several intracellular events. In hepatocytes and cholangiocytes, which are the epithelial cell types in the liver, inositol 1,4,5-trisphosphate (InsP3) receptors (ITPR) are the only intracellular calcium release channels. Three isoforms of the ITPR have been described, named type 1, type 2 and type 3. These ITPR isoforms are differentially expressed in liver cells where they regulate distinct physiological functions. Changes in the expression level of these receptors correlate with several liver diseases and hepatic dysfunctions. In this review, we highlight how the expression level, modulation, and localization of ITPR isoforms in hepatocytes and cholangiocytes play a role in hepatic homeostasis and liver pathology.
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Affiliation(s)
- Fernanda de Oliveira Lemos
- Department of Physiology and Biophysics, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Rodrigo M Florentino
- Department of Physiology and Biophysics, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Antônio Carlos Melo Lima Filho
- Department of Physiology and Biophysics, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Marcone Loiola dos Santos
- Department of Cell Biology, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - M Fatima Leite
- Department of Physiology and Biophysics, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
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Modica TME, Dituri F, Mancarella S, Pisano C, Fabregat I, Giannelli G. Calcium Regulates HCC Proliferation as well as EGFR Recycling/Degradation and Could Be a New Therapeutic Target in HCC. Cancers (Basel) 2019; 11:cancers11101588. [PMID: 31635301 PMCID: PMC6826902 DOI: 10.3390/cancers11101588] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 10/13/2019] [Indexed: 01/08/2023] Open
Abstract
Calcium is the most abundant element in the human body. Its role is essential in physiological and biochemical processes such as signal transduction from outside to inside the cell between the cells of an organ, as well as the release of neurotransmitters from neurons, muscle contraction, fertilization, bone building, and blood clotting. As a result, intra- and extracellular calcium levels are tightly regulated by the body. The liver is the most specialized organ of the body, as its functions, carried out by hepatocytes, are strongly governed by calcium ions. In this work, we analyze the role of calcium in human hepatoma (HCC) cell lines harboring a wild type form of the Epidermal Growth Factor Receptor (EGFR), particularly its role in proliferation and in EGFR downmodulation. Our results highlight that calcium is involved in the proliferative capability of HCC cells, as its subtraction is responsible for EGFR degradation by proteasome machinery and, as a consequence, for EGFR intracellular signaling downregulation. However, calcium-regulated EGFR signaling is cell line-dependent. In cells responding weakly to the epidermal growth factor (EGF), calcium seems to have an opposite effect on EGFR internalization/degradation mechanisms. These results suggest that besides EGFR, calcium could be a new therapeutic target in HCC.
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Affiliation(s)
- Teresa Maria Elisa Modica
- Department of Biomedical Science and Human Oncology, Università degli Studi di Bari Aldo Moro, 70121 Bari, Italy.
- Biogem S.C.A.R.L., 83031 Ariano Irpino (AV), Italy.
| | | | | | | | - Isabel Fabregat
- Bellvitge Biomedical Research Institute (IDIBELL) L'Hospitalet, 08907 Barcelona, Spain.
- Faculty of Medicine and Health Sciences, University of Barcelona, 08907 Barcelona, Spain.
- Oncology Program, CIBEREHD, Instituto de Salud Carlos III, 28029 Madrid, Spain.
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Khamphaya T, Chukijrungroat N, Saengsirisuwan V, Mitchell-Richards KA, Robert ME, Mennone A, Nathanson MH, Weerachayaphorn J, Weerachayaphorn J. Nonalcoholic fatty liver disease impairs expression of the type II inositol 1,4,5-trisphosphate receptor. Hepatology 2018; 67:560-574. [PMID: 29023819 PMCID: PMC5893412 DOI: 10.1002/hep.29588] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 09/07/2017] [Accepted: 10/04/2017] [Indexed: 02/06/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most prevalent liver disease worldwide. It may result in several types of liver problems, including impaired liver regeneration (LR), but the mechanism for this is unknown. Because LR depends on calcium signaling, we examined the effects of NAFLD on expression of the type II inositol 1,4,5-trisphosphate receptor (ITPR2), the principle calcium release channel in hepatocytes. ITPR2 promoter activity was measured in Huh7 and HepG2 cells. ITPR2 and c-Jun protein levels were evaluated in Huh7 cells, in liver tissue from a rat model of NAFLD, and in liver biopsy specimens of patients with simple steatosis and nonalcoholic steatohepatitis (NASH). LR was assessed in wild-type and Itpr2 knockout (Itpr2-/- ) mice following 67% hepatectomy. Cell proliferation was examined in ITPR2-knockout HepG2 cells generated by the CRISPR/Cas9 system. c-Jun dose dependently decreased activity of the human ITPR2 promoter. c-Jun expression was increased and ITPR2 was decreased in fat-loaded Huh7 cells and in livers of rats fed a high-fat, high-fructose diet. Overexpression of c-Jun reduced protein and mRNA expression of ITPR2 in Huh7 cells, whereas knockdown of c-Jun prevented the decrease of ITPR2 in fat-loaded Huh7 cells. ITPR2 expression was decreased and c-Jun was increased in liver biopsies of patients with steatosis and NASH compared to controls. ITPR2-knockout cells exhibited less nuclear calcium signaling and cell proliferation than control cells. LR assessed by Ki-67 and proliferating cell nuclear antigen was markedly decreased in Itpr2-/- mice. Conclusion: Fatty liver induces a c-Jun-mediated decrease in ITPR2 in hepatocytes. This may account for the impaired LR that occurs in NAFLD. (Hepatology 2018;67:560-574).
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Affiliation(s)
- Tanaporn Khamphaya
- Toxicology Graduate Program, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Natsasi Chukijrungroat
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Vitoon Saengsirisuwan
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | | | - Marie E. Robert
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06519, USA
| | - Albert Mennone
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven 06519, Connecticut, USA
| | - Michael H. Nathanson
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven 06519, Connecticut, USA,Corresponding Authors: Michael H. Nathanson, M.D., Ph.D., Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06519, USA. Phone: (+1) 203-785-7312; Fax: (+1) 203-785-7273, ; Jittima Weerachayaphorn, Ph.D., Department of Physiology, Faculty of Science, Mahidol University, Rama 6 Road, Ratchathewi, Bangkok 10400, Thailand. Phone: (+66) 2201-5514; Fax: (+66) 2354-7154, ,
| | - Jittima Weerachayaphorn
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand,Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven 06519, Connecticut, USA,Corresponding Authors: Michael H. Nathanson, M.D., Ph.D., Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06519, USA. Phone: (+1) 203-785-7312; Fax: (+1) 203-785-7273, ; Jittima Weerachayaphorn, Ph.D., Department of Physiology, Faculty of Science, Mahidol University, Rama 6 Road, Ratchathewi, Bangkok 10400, Thailand. Phone: (+66) 2201-5514; Fax: (+66) 2354-7154, ,
| | - Jittima Weerachayaphorn
- Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand.,Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT
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Oliveira AG, Andrade VA, Guimarães ES, Florentino RM, Sousa PA, Marques PE, Melo FM, Ortega MJ, Menezes GB, Leite MF. Calcium signalling from the type I inositol 1,4,5-trisphosphate receptor is required at early phase of liver regeneration. Liver Int 2015; 35:1162-71. [PMID: 24814243 DOI: 10.1111/liv.12587] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 04/30/2014] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS Liver regeneration is a multistage process that unfolds gradually, with different mediators acting at different stages of regeneration. Calcium (Ca(2+) ) signalling is essential for liver regeneration. In hepatocytes, Ca(2+) signalling results from the activation of inositol 1,4,5-trisphosphate receptors (InsP3 R) of which two of the three known isoforms are expressed (InsP3 R-I and InsP3 R-II). Here, we investigated the role of the InsP3 R-I-dependent Ca(2+) signals in hepatic proliferation during liver regeneration. METHODS Partial hepatectomy (HX) in combination with knockdown of InsP3 R-I (AdsiRNA-I) was used to evaluate the role of InsP3 R-I on liver regeneration and hepatocyte proliferation, as assessed by liver to body mass ratio, PCNA expression, immunoblots and measurements of intracellular Ca(2+) signalling. RESULTS AdsiRNA-I efficiently infected the liver as demonstrated by the expression of β-galactosidase throughout the liver lobules. Moreover, this construct selectively and efficiently reduced the expression of InsP3 R-I, as evaluated by immunoblots. Expression of AdsiRNA-I in liver decreased peak Ca(2+) amplitude induced by vasopressin in isolated hepatocytes 2 days after HX. Reduced InsP3 R-I expression prior to HX also delayed liver regeneration, as measured by liver to body weight ratio, and reduced hepatocyte proliferation, as evaluated by PCNA staining, at the same time point. At later stages of regeneration, control hepatocytes showed a decreased expression of InsP3 R, as well as reduced InsP3 R-mediated Ca(2+) signalling, events that did not affect liver growth. CONCLUSION Together, these results show that InsP3 R-I-dependent Ca(2+) signalling is an early triggering pathway required for liver regeneration.
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Affiliation(s)
- André G Oliveira
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
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Tackett BC, Sun H, Mei Y, Maynard JP, Cheruvu S, Mani A, Hernandez-Garcia A, Vigneswaran N, Karpen SJ, Thevananther S. P2Y2 purinergic receptor activation is essential for efficient hepatocyte proliferation in response to partial hepatectomy. Am J Physiol Gastrointest Liver Physiol 2014; 307:G1073-87. [PMID: 25301185 PMCID: PMC4254960 DOI: 10.1152/ajpgi.00092.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 09/30/2014] [Indexed: 01/31/2023]
Abstract
Extracellular nucleotides via activation of P2 purinergic receptors influence hepatocyte proliferation and liver regeneration in response to 70% partial hepatectomy (PH). Adult hepatocytes express multiple P2Y (G protein-coupled) and P2X (ligand-gated ion channels) purinergic receptor subtypes. However, the identity of key receptor subtype(s) important for efficient hepatocyte proliferation in regenerating livers remains unknown. To evaluate the impact of P2Y2 purinergic receptor-mediated signaling on hepatocyte proliferation in regenerating livers, wild-type (WT) and P2Y2 purinergic receptor knockout (P2Y2-/-) mice were subjected to 70% PH. Liver tissues were analyzed for activation of early events critical for hepatocyte priming and subsequent cell cycle progression. Our findings suggest that early activation of p42/44 ERK MAPK (5 min), early growth response-1 (Egr-1) and activator protein-1 (AP-1) DNA-binding activity (30 min), and subsequent hepatocyte proliferation (24-72 h) in response to 70% PH were impaired in P2Y2-/- mice. Interestingly, early induction of cytokines (TNF-α, IL-6) and cytokine-mediated signaling (NF-κB, STAT-3) were intact in P2Y2-/- remnant livers, uncovering the importance of cytokine-independent and nucleotide-dependent early priming events critical for subsequent hepatocyte proliferation in regenerating livers. Hepatocytes isolated from the WT and P2Y2-/- mice were treated with ATP or ATPγS for 5-120 min and 12-24 h. Extracellular ATP alone, via activation of P2Y2 purinergic receptors, was sufficient to induce ERK phosphorylation, Egr-1 protein expression, and key cyclins and cell cycle progression of hepatocytes in vitro. Collectively, these findings highlight the functional significance of P2Y2 purinergic receptor activation for efficient hepatocyte priming and proliferation in response to PH.
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Affiliation(s)
- Bryan C Tackett
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Texas Children's Liver Center, Houston, Texas; Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, Texas
| | - Hongdan Sun
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Texas Children's Liver Center, Houston, Texas
| | - Yu Mei
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Texas Children's Liver Center, Houston, Texas
| | - Janielle P Maynard
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Texas Children's Liver Center, Houston, Texas; Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, Texas
| | - Sayuri Cheruvu
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Texas Children's Liver Center, Houston, Texas
| | - Arunmani Mani
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Texas Children's Liver Center, Houston, Texas
| | | | - Nadarajah Vigneswaran
- Department of Diagnostic Sciences, University of Texas Dental Branch in Houston, Houston, Texas
| | - Saul J Karpen
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Texas Children's Liver Center, Houston, Texas; Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, Texas
| | - Sundararajah Thevananther
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Texas Children's Liver Center, Houston, Texas; Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, Texas;
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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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Báez-Ruiz A, Cázares-Gómez K, Vázquez-Martínez O, Aguilar-Roblero R, Díaz-Muñoz M. Diurnal and nutritional adjustments of intracellular Ca2+ release channels and Ca2+ ATPases associated with restricted feeding schedules in the rat liver. J Circadian Rhythms 2013; 11:8. [PMID: 23962056 PMCID: PMC3850936 DOI: 10.1186/1740-3391-11-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 08/07/2013] [Indexed: 01/18/2023] Open
Abstract
Background Intracellular calcium is a biochemical messenger that regulates part of the metabolic adaptations in the daily fed-fast cycle. The aim of this study was to characterize the 24-h variations of the liver ryanodine and IP3 receptors (RyR and IP3R) as well as of the endoplasmic-reticulum and plasma-membrane Ca2+-ATPases (SERCA and PMCA) in daytime restricted feeding protocol. Methods A biochemical and immunohistochemical approach was implemented in this study: specific ligand-binding for RyR and IP3R, enzymatic activity (SERCA and PMCA), and protein levels and zonational hepatic-distribution were determined by immunoblot and immunohistochemistry respectively under conditions of fasting, feeding, and temporal food-restriction. Results Binding assays and immunoblots for IP3R1 and 2 showed a peak at the light/dark transition in the ad-libitum (AL) group, whereas in the restricted-feeding (RF) group the peak shifted towards the food-access time. In the case of RyR binding experiments, both AL and RF groups showed a modest elevation during the dark period, with the RF rats exhibiting increased binding in response to feeding. The AL group showed 24-h rhythmicity in SERCA level; in contrast, RF group showed a pronounced amplitude elevation and a peak phase-shift during the light-period in SERCA level and activity. The activity of PMCA was constant along day in both groups; PMCA1 levels showed a 24-h rhythmicity in the RF rats (with a peak in the light period), meanwhile PMCA4 protein levels showed rhythmicity in both groups. The fasted condition promoted an increase in IP3R binding and protein level; re-feeding increased the amount of RyR; neither the activity nor expression of SERCA and PMCA protein was affected by fasting–re-feeding conditions. Histochemical experiments showed that the distribution of the Ca2+-handling proteins, between periportal and pericentral zones of the liver, varied with the time of day and the feeding protocol. Conclusions Our findings show that RF influences mainly the phase and amplitude of hepatic IP3R and SERCA rhythms as well as discrete zonational distribution for RyR, IP3Rs, SERCA, and PMCA within the liver acinus, suggesting that intracellular calcium dynamics could be part of the rheostatic adaptation of the liver due to diurnal meal entrainment/food entrained oscillator expression.
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Affiliation(s)
- Adrián Báez-Ruiz
- Departamento de Neurobiología Molecular y Celular, Instituto de Neurobiología, UNAM-Juriquilla, Boulevard Juriquilla #3001, Apdo, Postal 1-1141, Querétaro, QRO 76230, México.
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11
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Abstract
After partial hepatectomy (PH) the initial mass of the organ is restored through a complex network of cellular interactions that orchestrate both proliferative and hepatoprotective signalling cascades. Among agonists involved in this network many of them drive Ca(2+) movements. During liver regeneration in the rat, hepatocyte cytosolic Ca(2+) signalling has been shown on the one hand to be deeply remodelled and on the other hand to enhance progression of hepatocytes through the cell cycle. Mechanisms through which cytosolic Ca(2+) signals impact on hepatocyte cell cycle early after PH are not completely understood, but at least they include regulation of immediate early gene transcription and ERK and CREB phosphorylation. In addition to cytosolic Ca(2+), there is also evidence that mitochondrial Ca(2+) and also nuclear Ca(2+) may be critical for the regulation of liver regeneration. Finally, Ca(2+) movements in hepatocytes, and possibly in other liver cells, not only impact hepatocyte progression in the cell cycle but more generally may regulate cellular homeostasis after PH.
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Xie XL, Wei M, Kakehashi A, Yamano S, Tajiri M, Wanibuchi H. 2-Amino-3-Methylimidazo[4,5-f]Quinoline (IQ) Promotes Mouse Hepatocarcinogenesis by Activating Transforming Growth Factor- and Wnt/ -Catenin Signaling Pathways. Toxicol Sci 2011; 125:392-400. [DOI: 10.1093/toxsci/kfr314] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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13
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Guerra MT, Fonseca EA, Melo FM, Andrade VA, Aguiar CJ, Andrade LM, Pinheiro ACN, Casteluber MF, Resende RR, Pinto MCX, Fernandes SOA, Cardoso VN, Souza–Fagundes EM, Menezes GB, de Paula AM, Nathanson MH, Leite MF. Mitochondrial calcium regulates rat liver regeneration through the modulation of apoptosis. Hepatology 2011; 54:296-306. [PMID: 21503946 PMCID: PMC3125477 DOI: 10.1002/hep.24367] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
UNLABELLED Subcellular Ca(2+) signals control a variety of responses in the liver. For example, mitochondrial Ca(2+) (Ca(mit)(2+)) regulates apoptosis, whereas Ca(2+) in the nucleus regulates cell proliferation. Because apoptosis and cell growth can be related, we investigated whether Ca(mit)(2+) also affects liver regeneration. The Ca(2+)-buffering protein parvalbumin, which was targeted to the mitochondrial matrix and fused to green fluorescent protein, was expressed in the SKHep1 liver cell line; the vector was called parvalbumin-mitochondrial targeting sequence-green fluorescent protein (PV-MITO-GFP). This construct properly localized to and effectively buffered Ca(2+) signals in the mitochondrial matrix. Additionally, the expression of PV-MITO-GFP reduced apoptosis induced by both intrinsic and extrinsic pathways. The reduction in cell death correlated with the increased expression of antiapoptotic genes [B cell lymphoma 2 (bcl-2), myeloid cell leukemia 1, and B cell lymphoma extra large] and with the decreased expression of proapoptotic genes [p53, B cell lymphoma 2-associated X protein (bax), apoptotic peptidase activating factor 1, and caspase-6]. PV-MITO-GFP was also expressed in hepatocytes in vivo with an adenoviral delivery system. Ca(mit)(2+) buffering in hepatocytes accelerated liver regeneration after partial hepatectomy, and this effect was associated with the increased expression of bcl-2 and the decreased expression of bax. CONCLUSION Together, these results reveal an essential role for Ca(mit)(2+) in hepatocyte proliferation and liver regeneration, which may be mediated by the regulation of apoptosis.
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Affiliation(s)
- Mateus T. Guerra
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil, Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - Emerson A. Fonseca
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Flavia M. Melo
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - V. A Andrade
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Carla J. Aguiar
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil, Izabela Hendrix Metodist Institute
| | - Lídia M. Andrade
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil, René Rachou Research Center, Oswaldo Cruz Foundation
| | - Ana Cristina N. Pinheiro
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Marisa F. Casteluber
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Rodrigo R. Resende
- Nanobiotechnology Laboratory, Federal University of São João del Rei, Brazil
| | - Mauro C. X. Pinto
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Simone O. A. Fernandes
- Radioisotope Laboratory, Department of Clinical and Toxicological Analysis – Faculty of Pharmacy, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Valbert N. Cardoso
- Radioisotope Laboratory, Department of Clinical and Toxicological Analysis – Faculty of Pharmacy, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Elaine M. Souza–Fagundes
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Gustavo B. Menezes
- Department of Morphology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ana M. de Paula
- Department of Physics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Michael H. Nathanson
- Section of Digestive Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
| | - M. Fatima Leite
- Department of Physiology and Biophysics, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil, Howard Hughes Medical Institute
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14
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Abou-Lovergne A, Collado-Hilly M, Monnet FP, Koukoui O, Prigent S, Coquil JF, Dupont G, Combettes L. Investigation of the role of sigma1-receptors in inositol 1,4,5-trisphosphate dependent calcium signaling in hepatocytes. Cell Calcium 2011; 50:62-72. [PMID: 21641033 DOI: 10.1016/j.ceca.2011.05.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 05/05/2011] [Accepted: 05/07/2011] [Indexed: 11/22/2022]
Abstract
In hepatocytes, as in other cell types, Ca(2+) signaling is subject to complex regulations, which result largely from the intrinsic characteristics of the different inositol 1,4,5-trisphosphate receptor (InsP(3)R) isoforms and from their interactions with other proteins. Although sigma1 receptors (Sig-1Rs) are widely expressed in the liver, their involvement in hepatic Ca(2+) signaling remains unknown. We here report that in this cell type Sig-1R interact with type 1 isoforms of the InsP(3) receptors (InsP(3)R-1). These results obtained by immunoprecipitation experiments are confirmed by the observation that Sig-1R proteins and InsP(3)R-1 colocalize in hepatocytes. However, Sig-1R ligands have no effect on InsP(3)-induced Ca(2+) release in hepatocytes. This can be explained by the rather low expression level expression of InsP(3)R-1. In contrast, we find that Sig-1R ligands can inhibit agonist-induced Ca(2+) signaling via an inhibitory effect on InsP(3) synthesis. We show that this inhibition is due to the stimulation of PKC activity by Sig-1R, resulting in the well-known down-regulation of the signaling pathway responsible for the transduction of the extracellular stimulus into InsP(3) synthesis. The PKC sensitive to Sig-1R activity belongs to the family of conventional PKC, but the precise molecular mechanism of this regulation remains to be elucidated.
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MESH Headings
- Animals
- Calcium/metabolism
- Calcium Signaling
- Cells, Cultured
- Female
- Fura-2/pharmacology
- Hepatocytes/metabolism
- Inositol 1,4,5-Trisphosphate/metabolism
- Inositol 1,4,5-Trisphosphate Receptors/analysis
- Inositol 1,4,5-Trisphosphate Receptors/metabolism
- Norepinephrine/pharmacology
- Pentazocine/pharmacology
- Protein Kinase C/metabolism
- Rats
- Rats, Wistar
- Receptors, sigma/analysis
- Receptors, sigma/metabolism
- Receptors, sigma/physiology
- Vasopressins/pharmacology
- Sigma-1 Receptor
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Affiliation(s)
- A Abou-Lovergne
- Institut National de la Santé et de la Recherche Médicale Unité UMR-S757, France
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15
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Combettes L, Dupont G. [Experimental and computational approach of calcium signaling]. Med Sci (Paris) 2011; 27:170-6. [PMID: 21382325 DOI: 10.1051/medsci/2011272170] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
In many cell types, specific and robust signalling relies on a high level of spatiotemporal organization of Ca(2+) dynamics. In response to external stimulation, Ca(2+) signals ranging from a small increase of a few tens of nanomolar concentrations at the mouth of an inositol 1, 4, 5-trisphosphate receptor to the periodic propagation of waves invading an organ or a tissue, can be observed. Here, we review our combined experimental and computational approach of Ca(2+) dynamics, which has been mainly carried out on liver hepatocytes. We focus in particular on the understanding of the relationship between elementary Ca(2+) increases, Ca(2+) oscillations and intra- or intercellular Ca(2+) waves. The physiological impact of such signalling on liver function is also discussed.
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16
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Dupont G, Combettes L, Bird GS, Putney JW. Calcium oscillations. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a004226. [PMID: 21421924 DOI: 10.1101/cshperspect.a004226] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Calcium signaling results from a complex interplay between activation and inactivation of intracellular and extracellular calcium permeable channels. This complexity is obvious from the pattern of calcium signals observed with modest, physiological concentrations of calcium-mobilizing agonists, which typically present as sequential regenerative discharges of stored calcium, a process referred to as calcium oscillations. In this review, we discuss recent advances in understanding the underlying mechanism of calcium oscillations through the power of mathematical modeling. We also summarize recent findings on the role of calcium entry through store-operated channels in sustaining calcium oscillations and in the mechanism by which calcium oscillations couple to downstream effectors.
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Affiliation(s)
- Geneviève Dupont
- Unité de Chronobiologie Théorique, Université Libre de Bruxelles, Faculté des Sciences, Brussels, Belgium
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17
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Ozkucur N, Epperlein HH, Funk RHW. Ion imaging during axolotl tail regeneration in vivo. Dev Dyn 2010; 239:2048-57. [PMID: 20549718 DOI: 10.1002/dvdy.22323] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Several studies have reported that endogenous ion currents are involved in a wide range of biological processes from single cell and tissue behavior to regeneration. Various methods are used to assess intracellular and local ion dynamics in biological systems, e.g., patch clamping and vibrating probes. Here, we introduce an approach to detect ion kinetics in vivo using a noninvasive method that can electrophysiologically characterize an entire experimental tissue region or organism. Ion-specific vital dyes have been successfully used for live imaging of intracellular ion dynamics in vitro. Here, we demonstrate that cellular pH, cell membrane potential, calcium, sodium and potassium can be monitored in vivo during tail regeneration in the axolotl (Ambystoma mexicanum) using ion-specific vital dyes. Thus, we suggest that ion-specific vital dyes can be a powerful tool to obtain electrophysiological data during crucial biological events in vivo.
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Affiliation(s)
- Nurdan Ozkucur
- Department of Anatomy, Medical Faculty Carl Gustav Carus, TU Dresden, Fetscherstrasse 74, Dresden, Germany.
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18
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Teixeira-Clerc F, Belot MP, Manin S, Deveaux V, Cadoudal T, Chobert MN, Louvet A, Zimmer A, Tordjmann T, Mallat A, Lotersztajn S. Beneficial paracrine effects of cannabinoid receptor 2 on liver injury and regeneration. Hepatology 2010; 52:1046-59. [PMID: 20597071 PMCID: PMC3246453 DOI: 10.1002/hep.23779] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UNLABELLED The cannabinoid receptor 2 (CB2) plays a pleiotropic role in innate immunity and is a crucial mediator of liver disease. In this study, we investigated the impact of CB2 receptors on the regenerative process associated with liver injury. Following acute hepatitis induced by carbon tetrachloride (CCl(4)), CB2 was induced in the nonparenchymal cell fraction and remained undetectable in hepatocytes. Administration of CCl(4) to CB2(-/-) mice accelerated liver injury, as shown by increased alanine/aspartate aminotransferase levels and hepatocyte apoptosis, and delayed liver regeneration, as reflected by a retarded induction of hepatocyte proliferating cell nuclear antigen expression; proliferating cell nuclear antigen induction was also delayed in CB2(-/-) mice undergoing partial hepatectomy. Conversely, following treatment with the CB2 agonist JWH-133, CCl(4)-treated WT mice displayed reduced liver injury and accelerated liver regeneration. The CCl(4)-treated CB2(-/-) mice showed a decrease in inducible nitric oxide synthase and tumor necrosis factor-alpha expression, and administration of the nitric oxide donor moldomine (SIN-1) to these animals reduced hepatocyte apoptosis, without affecting liver regeneration. Impaired liver regeneration was consecutive to an interleukin-6 (IL-6)-mediated decrease in matrix metalloproteinase 2 (MMP-2) activity. Indeed, CCl(4)-treated CB2(-/-) mice displayed lower levels of hepatic IL-6 messenger RNA and increased MMP-2 activity. Administration of IL-6 to these mice decreased MMP-2 activity and improved liver regeneration, without affecting hepatocyte apoptosis. Accordingly, administration of the MMP inhibitor CTTHWGFTLC to CCl(4)-treated CB2(-/-) mice improved liver regeneration. Finally, in vitro studies demonstrated that incubation of hepatic myofibroblasts with JWH-133 increased tumor necrosis factor-alpha and IL-6 and decreased MMP-2 expressions. CONCLUSION CB2 receptors reduce liver injury and promote liver regeneration following acute insult, via distinct paracrine mechanisms involving hepatic myofibroblasts. These results suggest that CB2 agonists display potent hepatoprotective properties, in addition to their antifibrogenic effects.
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Affiliation(s)
- Fatima Teixeira-Clerc
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR10FR
| | - Marie-Pierre Belot
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR10FR
| | - Sylvie Manin
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR10FR
| | - Vanessa Deveaux
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR10FR
| | - Thomas Cadoudal
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR10FR
| | - Marie-Noele Chobert
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR10FR
| | - Alexandre Louvet
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR10FR
| | - Andreas Zimmer
- Department of Molecular Psychiatry
Bonn Universität - University of BonnDE
| | - Thierry Tordjmann
- Signalisation Cellulaire et Calcium
INSERM : U757Université Paris Sud - Paris XIUniversite Paris-Sud PARIS XI Rue Georges Clemenceau 91405 ORSAY CEDEX,FR
| | - Ariane Mallat
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR10FR,Service d'hépatologie et de gastroentérologie
Hôpital Henri MondorAssistance publique - Hôpitaux de Paris (AP-HP)Créteil,FR
| | - Sophie Lotersztajn
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR10FR,* Correspondence should be adressed to: Sophie Lotersztajn
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19
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Lagoudakis L, Garcin I, Julien B, Nahum K, Gomes DA, Combettes L, Nathanson MH, Tordjmann T. Cytosolic calcium regulates liver regeneration in the rat. Hepatology 2010; 52:602-11. [PMID: 20683958 PMCID: PMC3572840 DOI: 10.1002/hep.23673] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
UNLABELLED Liver regeneration is regulated by growth factors, cytokines, and other endocrine and metabolic factors. Calcium is important for cell division, but its role in liver regeneration is not known. The purpose of this study was to understand the effects of cytosolic calcium signals in liver growth after partial hepatectomy (PH). The gene encoding the calcium-binding protein parvalbumin (PV) targeted to the cytosol using a nuclear export sequence (NES), and using a discosoma red fluorescent protein (DsR) marker, was transfected into rat livers by injecting it, in recombinant adenovirus (Ad), into the portal vein. We performed two-thirds PH 4 days after Ad-PV-NES-DsR or Ad-DsR injection, and liver regeneration was analyzed. Calcium signals were analyzed with fura-2-acetoxymethyl ester in hepatocytes isolated from Ad-infected rats and in Ad-infected Hela cells. Also, isolated hepatocytes were infected with Ad-DsR or Ad-PV-NES-DsR and assayed for bromodeoxyuridine incorporation. Ad-PV-NES-DsR injection resulted in PV expression in the hepatocyte cytosol. Agonist-induced cytosolic calcium oscillations were attenuated in both PV-NES-expressing Hela cells and hepatocytes, as compared to DsR-expressing cells. Bromodeoxyuridine incorporation (S phase), phosphorylated histone 3 immunostaining (mitosis), and liver mass restoration after PH were all significantly delayed in PV-NES rats. Reduced cyclin expression and retinoblastoma protein phosphorylation confirmed this observation. PV-NES rats exhibited reduced c-fos induction and delayed extracellular signal-regulated kinase 1/2 phosphorylation after PH. Finally, primary PV-NES-expressing hepatocytes exhibited less proliferation and agonist-induced cyclic adenosine monophosphate responsive element binding and extracellular signal-regulated kinase 1/2 phosphorylation, as compared with control cells. CONCLUSION Cytosolic calcium signals promote liver regeneration by enhancing progression of hepatocytes through the cell cycle.
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Affiliation(s)
- Laura Lagoudakis
- Institut National de la Santéet de la Recherche Médicale (INSERM) U757, UniversitéParis-sud, Orsay, France
| | - Isabelle Garcin
- Institut National de la Santéet de la Recherche Médicale (INSERM) U757, UniversitéParis-sud, Orsay, France
| | - Boris Julien
- Institut National de la Santéet de la Recherche Médicale (INSERM) U757, UniversitéParis-sud, Orsay, France
| | - Kis Nahum
- Institut National de la Santéet de la Recherche Médicale (INSERM) U757, UniversitéParis-sud, Orsay, France
| | - Dawidson A. Gomes
- Federal University of Minas Gerais, Belo Horizonte-Minas Gerais, Brazil
| | - Laurent Combettes
- Institut National de la Santéet de la Recherche Médicale (INSERM) U757, UniversitéParis-sud, Orsay, France
| | | | - Thierry Tordjmann
- Institut National de la Santéet de la Recherche Médicale (INSERM) U757, UniversitéParis-sud, Orsay, France
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20
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Dupont G, Combettes L. What can we learn from the irregularity of Ca2+ oscillations? CHAOS (WOODBURY, N.Y.) 2009; 19:037112. [PMID: 19792037 DOI: 10.1063/1.3160569] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In most cells, Ca(2+) increases in response to external stimulation are organized in the form of oscillations and waves that sometimes propagate from one cell to another. Numerous experimental and theoretical studies reveal that this spatiotemporal organization contains a non-negligible level of stochasticity. In this study, we extend the previous work based on a statistical analysis of experimental Ca(2+) traces in isolated, hormone-stimulated hepatocytes and on stochastic simulations of Ca(2+) oscillations based on the Gillespie's algorithm. Comparison of the coefficients of variation in the periods of experimental and simulated Ca(2+) spikes provides information about the clustering and the specific subtypes of the Ca(2+) channels. In hepatocytes coupled by gap junctions, the global perfusion with a hormone leads to successive Ca(2+) responses, giving the appearance of an intercellular wave. Statistical analysis of experimental Ca(2+) oscillations in coupled hepatocytes confirms that this coordinated Ca(2+) spiking corresponds to a phase wave but suggests the existence of an additional coupling mechanism.
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Affiliation(s)
- Geneviève Dupont
- Unité de Chronobiologie Théorique, Faculté des Sciences, Université Libre de Bruxelles, Brussels, Belgium
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21
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Vigant F, Descamps D, Jullienne B, Esselin S, Connault E, Opolon P, Tordjmann T, Vigne E, Perricaudet M, Benihoud K. Substitution of hexon hypervariable region 5 of adenovirus serotype 5 abrogates blood factor binding and limits gene transfer to liver. Mol Ther 2008; 16:1474-80. [PMID: 18560416 DOI: 10.1038/mt.2008.132] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Liver tropism potentially leading to massive hepatocyte transduction and hepatotoxicity still represents a major drawback to adenovirus (Ad)-based gene therapy. We previously demonstrated that substitution of the hexon hypervariable region 5 (HVR5), the most abundant capsid protein, constituted a valuable platform for efficient Ad retargeting. The use of different mouse strains revealed that HVR5 substitution also led to dramatically less adenovirus liver transduction and associated toxicity, whereas HVR5-modified Ad were still able to transduce different cell lines efficiently, including primary hepatocytes. We showed that HVR5 modification did not significantly change Ad blood clearance or liver uptake at early times. However, we were able to link the lower liver transduction to enhanced HVR5-modified Ad liver clearance and impaired use of blood factors. Most importantly, HVR5-modified vectors continued to transduce tumors in vivo as efficiently as their wild-type counterparts. Taken together, our data provide a rationale for future design of retargeted vectors with a safer profile.
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Affiliation(s)
- Frédéric Vigant
- CNRS UMR 8121, Vectorologie et Transfert de Gènes, Institut Gustave Roussy, Villejuif Cedex, France
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22
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Soriano V, Perelson AS, Zoulim F. Why are there different dynamics in the selection of drug resistance in HIV and hepatitis B and C viruses? J Antimicrob Chemother 2008; 62:1-4. [PMID: 18441341 DOI: 10.1093/jac/dkn175] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The arrival of new antiviral drugs to treat chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections has given rise to great expectations along with concerns regarding the selection of drug-resistant variants. Many lessons learnt from HIV therapeutics can be helpful for designing adequate treatment strategies against viral hepatitis, the avoidance of sequential weak monotherapies being one of them. Although HIV, HBV and HCV share many biological features, including very rapid viral dynamics, distinctive characteristics explain why the speed of selection of drug resistance differs substantially between these viruses, being faster for HCV than for HIV and slower for HBV.
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Affiliation(s)
- Vincent Soriano
- Department of Infectious Diseases, Hospital Carlos III, Sinesio Delgado 10, 28029 Madrid, Spain.
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23
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Dupont G, Combettes L, Leybaert L. Calcium Dynamics: Spatio‐Temporal Organization from the Subcellular to the Organ Level. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 261:193-245. [PMID: 17560283 DOI: 10.1016/s0074-7696(07)61005-5] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Many essential physiological processes are controlled by calcium. To ensure reliability and specificity, calcium signals are highly organized in time and space in the form of oscillations and waves. Interesting findings have been obtained at various scales, ranging from the stochastic opening of a single calcium channel to the intercellular calcium wave spreading through an entire organ. A detailed understanding of calcium dynamics thus requires a link between observations at different scales. It appears that some regulations such as calcium-induced calcium release or PLC activation by calcium, as well as the weak diffusibility of calcium ions play a role at all levels of organization in most cell types. To comprehend how calcium waves spread from one cell to another, specific gap-junctional coupling and paracrine signaling must also be taken into account. On the basis of a pluridisciplinar approach ranging from physics to physiology, a unified description of calcium dynamics is emerging, which could help understanding how such a small ion can mediate so many vital functions in living systems.
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Affiliation(s)
- Geneviève Dupont
- Theoretical Chronobiology Unit, Université Libre de Bruxelles, Faculté des Sciences, 1050 Brussels, Belgium
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