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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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3
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Pozo-Morales M, Garteizgogeascoa I, Perazzolo C, So J, Shin D, Singh SP. In vivo imaging of calcium dynamics in zebrafish hepatocytes. Hepatology 2023; 77:789-801. [PMID: 35829917 DOI: 10.1002/hep.32663] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 06/30/2022] [Accepted: 07/04/2022] [Indexed: 12/19/2022]
Abstract
BACKGROUND AND AIMS Hepatocytes were the first cell type for which oscillations of cytoplasmic calcium levels in response to hormones were described. Since then, investigation of calcium dynamics in liver explants and culture has greatly increased our understanding of calcium signaling. A bottleneck, however, exists in observing calcium dynamics in a noninvasive manner because of the optical inaccessibility of the mammalian liver. Here, we aimed to take advantage of the transparency of the zebrafish larvae to image hepatocyte calcium dynamics in vivo at cellular resolution. APPROACH AND RESULTS We developed a transgenic model expressing a calcium sensor, GCaMP6s, specifically in zebrafish hepatocytes. Using this, we provide a quantitative assessment of intracellular calcium dynamics during multiple contexts, including growth, feeding, ethanol-induced stress, and cell ablation. Specifically, we show that synchronized calcium oscillations are present in vivo , which are lost upon starvation. Starvation induces lipid accumulation in the liver. Feeding recommences calcium waves in the liver, but in a spatially restricted manner, as well as resolves starvation-induced hepatic steatosis. By using a genetically encoded scavenger for calcium, we show that dampening of calcium signaling accelerates the accumulation of starvation-related lipid droplets in the liver. Furthermore, ethanol treatment, as well as cell ablation, induces calcium flux, but with different dynamics. The former causes asynchronous calcium oscillations, whereas the latter leads to a single calcium spike. CONCLUSIONS We demonstrate the presence of oscillations, waves, and spikes in vivo . Calcium waves are present in response to nutrition and negatively regulate starvation-induced accumulation of lipid droplets.
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Affiliation(s)
- Macarena Pozo-Morales
- IRIBHM , Free University of Brussels, Université Libre de Bruxelles (ULB) , Brussels , Belgium
| | - Inés Garteizgogeascoa
- IRIBHM , Free University of Brussels, Université Libre de Bruxelles (ULB) , Brussels , Belgium
| | - Camille Perazzolo
- IRIBHM , Free University of Brussels, Université Libre de Bruxelles (ULB) , Brussels , Belgium
| | - Juhoon So
- Department of Developmental Biology , McGowan Institute for Regenerative Medicine , Pittsburgh Liver Research Center , University of Pittsburgh , Pittsburgh , Pennsylvania , USA
| | - Donghun Shin
- Department of Developmental Biology , McGowan Institute for Regenerative Medicine , Pittsburgh Liver Research Center , University of Pittsburgh , Pittsburgh , Pennsylvania , USA
| | - Sumeet Pal Singh
- IRIBHM , Free University of Brussels, Université Libre de Bruxelles (ULB) , Brussels , Belgium
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Zhang L, Wang W, Liu L, Zhang Y, Zhang X. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha protects a fibrotic liver from partial hepatectomy-induced advanced liver injury through regulating cell cycle arrest. Basic Clin Pharmacol Toxicol 2021; 130:254-267. [PMID: 34845850 PMCID: PMC9300180 DOI: 10.1111/bcpt.13697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 11/04/2021] [Accepted: 11/22/2021] [Indexed: 11/30/2022]
Abstract
Background A fibrotic liver may have an impaired regenerative capacity. Because liver transplantation is donor limited, understanding the regenerative ability of a fibrotic liver is important. Methods A two‐thirds partial hepatectomy (PH) was performed in C57Bl/6 mice with or without carbon tetrachloride (CCl4) treatment. Liver regeneration in the fibrotic liver after PH was assessed by the intrahepatic expression of the cell cycle regulators p53, p21, cyclin D1, c‐Fos and CDK2 using Western blot analysis. In addition, the expression of PGC‐1α and the cell proliferation‐related proteins PCNA and phosphate histone H3 was determined by Western blot and immunohistochemical staining analyses. Histone epigenetic modification of the PGC‐1α promoter was investigated through chromatin immunoprecipitation (ChIP) and reverse transcription–quantitative polymerase chain reaction (RT‐qPCR) assays. The impact of PGC‐1α on liver regeneration after PH was further evaluated in PGC‐1α‐knockout mice. Results A decreased expression of PGC‐1α and liver regeneration‐related genes in the fibrotic liver was detected after a PH. Histone acetylation at the PGC‐1α promoter led to increases in PGC‐1α expression and the survival rate in the fibrotic group after a PH. PGC‐1α‐mediated liver regeneration was further demonstrated in PGC‐1αf/falbcre+/0 mice. Conclusion Targeting PGC‐1α may represent a strategy to improve the treatment of PH in patients with liver fibrosis.
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Affiliation(s)
- Linzhong Zhang
- Department of Histology and Embryology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Wei Wang
- Department of Urology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Lipeng Liu
- Department of Histology and Embryology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Yanghao Zhang
- Department of Histology and Embryology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Xiuying Zhang
- Department of Histology and Embryology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
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5
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Receptor-specific Ca 2+ oscillation patterns mediated by differential regulation of P2Y purinergic receptors in rat hepatocytes. iScience 2021; 24:103139. [PMID: 34646983 PMCID: PMC8496176 DOI: 10.1016/j.isci.2021.103139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 07/26/2021] [Accepted: 09/14/2021] [Indexed: 11/21/2022] Open
Abstract
Extracellular agonists linked to inositol-1,4,5-trisphosphate (IP3) formation elicit cytosolic Ca2+ oscillations in many cell types, but despite a common signaling pathway, distinct agonist-specific Ca2+ spike patterns are observed. Using qPCR, we show that rat hepatocytes express multiple purinergic P2Y and P2X receptors (R). ADP acting through P2Y1R elicits narrow Ca2+ oscillations, whereas UTP acting through P2Y2R elicits broad Ca2+ oscillations, with composite patterns observed for ATP. P2XRs do not play a role at physiological agonist levels. The discrete Ca2+ signatures reflect differential effects of protein kinase C (PKC), which selectively modifies the falling phase of the Ca2+ spikes. Negative feedback by PKC limits the duration of P2Y1R-induced Ca2+ spikes in a manner that requires extracellular Ca2+. By contrast, P2Y2R is resistant to PKC negative feedback. Thus, the PKC leg of the bifurcated IP3 signaling pathway shapes unique Ca2+ oscillation patterns that allows for distinct cellular responses to different agonists. Distinct stereotypic Ca2+ oscillations are elicited by P2Y1 and P2Y2 receptors P2X receptors do not contribute to the generation of Ca2+ oscillations Agonist-specific Ca2+ spike shapes reflect discrete modes of PKC negative feedback Bifurcation of IP3/PKC signaling yields unique Ca2+ oscillation signatures
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Gaspers LD, Thomas AP, Hoek JB, Bartlett PJ. Ethanol Disrupts Hormone-Induced Calcium Signaling in Liver. FUNCTION (OXFORD, ENGLAND) 2021; 2:zqab002. [PMID: 33604575 PMCID: PMC7875097 DOI: 10.1093/function/zqab002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/22/2020] [Accepted: 12/30/2020] [Indexed: 01/06/2023]
Abstract
Receptor-coupled phospholipase C (PLC) is an important target for the actions of ethanol. In the ex vivo perfused rat liver, concentrations of ethanol >100 mM were required to induce a rise in cytosolic calcium (Ca2+) suggesting that these responses may only occur after binge ethanol consumption. Conversely, pharmacologically achievable concentrations of ethanol (≤30 mM) decreased the frequency and magnitude of hormone-stimulated cytosolic and nuclear Ca2+ oscillations and the parallel translocation of protein kinase C-β to the membrane. Ethanol also inhibited gap junction communication resulting in the loss of coordinated and spatially organized intercellular Ca2+ waves in hepatic lobules. Increasing the hormone concentration overcame the effects of ethanol on the frequency of Ca2+ oscillations and amplitude of the individual Ca2+ transients; however, the Ca2+ responses in the intact liver remained disorganized at the intercellular level, suggesting that gap junctions were still inhibited. Pretreating hepatocytes with an alcohol dehydrogenase inhibitor suppressed the effects of ethanol on hormone-induced Ca2+ increases, whereas inhibiting aldehyde dehydrogenase potentiated the inhibitory actions of ethanol, suggesting that acetaldehyde is the underlying mediator. Acute ethanol intoxication inhibited the rate of rise and the magnitude of hormone-stimulated production of inositol 1,4,5-trisphosphate (IP3), but had no effect on the size of Ca2+ spikes induced by photolysis of caged IP3. These findings suggest that ethanol inhibits PLC activity, but does not affect IP3 receptor function. We propose that by suppressing hormone-stimulated PLC activity, ethanol interferes with the dynamic modulation of [IP3] that is required to generate large, amplitude Ca2+ oscillations.
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Affiliation(s)
- Lawrence D Gaspers
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA,Address correspondence to L.D.G. (e-mail: )
| | - Andrew P Thomas
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Jan B Hoek
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Paula J Bartlett
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
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Golenberg N, Squirrell JM, Bennin DA, Rindy J, Pistono PE, Eliceiri KW, Shelef MA, Kang J, Huttenlocher A. Citrullination regulates wound responses and tissue regeneration in zebrafish. J Cell Biol 2020; 219:133858. [PMID: 32328635 PMCID: PMC7147109 DOI: 10.1083/jcb.201908164] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 12/17/2019] [Accepted: 01/31/2020] [Indexed: 01/05/2023] Open
Abstract
Calcium is an important early signal in wound healing, yet how these early signals promote regeneration remains unclear. Peptidylarginine deiminases (PADs), a family of calcium-dependent enzymes, catalyze citrullination, a post-translational modification that alters protein function and has been implicated in autoimmune diseases. We generated a mutation in the single zebrafish ancestral pad gene, padi2, that results in a loss of detectable calcium-dependent citrullination. The mutants exhibit impaired resolution of inflammation and regeneration after caudal fin transection. We identified a new subpopulation of cells displaying citrullinated histones within the notochord bead following tissue injury. Citrullination of histones in this region was absent, and wound-induced proliferation was perturbed in Padi2-deficient larvae. Taken together, our results show that Padi2 is required for the citrullination of histones within a group of cells in the notochord bead and for promoting wound-induced proliferation required for efficient regeneration. These findings identify Padi2 as a potential intermediary between early calcium signaling and subsequent tissue regeneration.
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Affiliation(s)
- Netta Golenberg
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI.,Cell and Molecular Biology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI
| | - Jayne M Squirrell
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, WI
| | - David A Bennin
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI.,Department of Pediatrics, University of Wisconsin-Madison, Madison, WI
| | - Julie Rindy
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI.,Department of Pediatrics, University of Wisconsin-Madison, Madison, WI
| | - Paige E Pistono
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI.,Department of Pediatrics, University of Wisconsin-Madison, Madison, WI
| | - Kevin W Eliceiri
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, WI
| | - Miriam A Shelef
- Department of Medicine, University of Wisconsin-Madison, Madison, WI.,William S. Middleton Memorial Veterans Hospital, Madison, WI
| | - Junsu Kang
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI
| | - Anna Huttenlocher
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI.,Department of Pediatrics, University of Wisconsin-Madison, Madison, WI
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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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Oliva-Vilarnau N, Hankeova S, Vorrink SU, Mkrtchian S, Andersson ER, Lauschke VM. Calcium Signaling in Liver Injury and Regeneration. Front Med (Lausanne) 2018; 5:192. [PMID: 30023358 PMCID: PMC6039545 DOI: 10.3389/fmed.2018.00192] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/11/2018] [Indexed: 12/12/2022] Open
Abstract
The liver fulfills central roles in metabolic control and detoxification and, as such, is continuously exposed to a plethora of insults. Importantly, the liver has a unique ability to regenerate and can completely recoup from most acute, non-iterative insults. However, multiple conditions, including viral hepatitis, non-alcoholic fatty liver disease (NAFLD), long-term alcohol abuse and chronic use of certain medications, can cause persistent injury in which the regenerative capacity eventually becomes dysfunctional, resulting in hepatic scaring and cirrhosis. Calcium is a versatile secondary messenger that regulates multiple hepatic functions, including lipid and carbohydrate metabolism, as well as bile secretion and choleresis. Accordingly, dysregulation of calcium signaling is a hallmark of both acute and chronic liver diseases. In addition, recent research implicates calcium transients as essential components of liver regeneration. In this review, we provide a comprehensive overview of the role of calcium signaling in liver health and disease and discuss the importance of calcium in the orchestration of the ensuing regenerative response. Furthermore, we highlight similarities and differences in spatiotemporal calcium regulation between liver insults of different etiologies. Finally, we discuss intracellular calcium control as an emerging therapeutic target for liver injury and summarize recent clinical findings of calcium modulation for the treatment of ischemic-reperfusion injury, cholestasis and NAFLD.
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Affiliation(s)
- Nuria Oliva-Vilarnau
- Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Simona Hankeova
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden.,Faculty of Science, Institute of Experimental Biology, Masaryk University, Brno, Czechia
| | - Sabine U Vorrink
- Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Souren Mkrtchian
- Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Emma R Andersson
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden.,Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Volker M Lauschke
- Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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Panahi G, Pasalar P, Zare M, Rizzuto R, Meshkani R. MCU-knockdown attenuates high glucose-induced inflammation through regulating MAPKs/NF-κB pathways and ROS production in HepG2 cells. PLoS One 2018; 13:e0196580. [PMID: 29709004 PMCID: PMC5927441 DOI: 10.1371/journal.pone.0196580] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/16/2018] [Indexed: 01/25/2023] Open
Abstract
Mitochondrial Ca2+ is a key regulator of organelle physiology and the excessive increase in mitochondrial calcium is associated with the oxidative stress. In the present study, we investigated the molecular mechanisms linking mitochondrial calcium to inflammatory and coagulative responses in hepatocytes exposed to high glucose (HG) (33mM glucose). Treatment of HepG2 cells with HG for 24 h induced insulin resistance, as demonstrated by an impairment of insulin-stimulated Akt phosphorylation. HepG2 treatment with HG led to an increase in mitochondrial Ca2+ uptake, while cytosolic calcium remained unchanged. Inhibition of MCU by lentiviral-mediated shRNA prevented mitochondrial calcium uptake and downregulated the inflammatory (TNF-α, IL-6) and coagulative (PAI-1 and FGA) mRNA expression in HepG2 cells exposed to HG. The protection from HG-induced inflammation by MCU inhibition was accompanied by a decrease in the generation of reactive oxygen species (ROS). Importantly, MCU inhibition in HepG2 cells abrogated the phosphorylation of p38, JNK and IKKα/IKKβ in HG treated cells. Taken together, these data suggest that MCU inhibition may represent a promising therapy for prevention of deleterious effects of obesity and metabolic diseases.
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Affiliation(s)
- Ghodratollah Panahi
- Department of Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, I.R Iran
| | - Parvin Pasalar
- Department of Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, I.R Iran
| | - Mina Zare
- Recombinant Protein Laboratory, Department of Biochemistry, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padova, Padua, Italy
| | - Reza Meshkani
- Department of Biochemistry, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, I.R Iran
- * E-mail:
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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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Kruglov E, Ananthanarayanan M, Sousa P, Weerachayaphorn J, Guerra MT, Nathanson MH. Type 2 inositol trisphosphate receptor gene expression in hepatocytes is regulated by cyclic AMP. Biochem Biophys Res Commun 2017; 486:659-664. [PMID: 28327356 DOI: 10.1016/j.bbrc.2017.03.086] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 03/17/2017] [Indexed: 01/19/2023]
Abstract
The type 2 inositol 1,4,5-trisphosphate receptor (IP3R2) is the principal intracellular Ca2+ release channel in hepatocytes, and so is important for bile secretion and other functions. IP3R2 activity is regulated in part by post-translational modifications but little is known about transcriptional regulation of its expression. We found that both IP3R2 mRNA and protein levels in liver were increased during fasting. Treatment of hepatocytes with forskolin or 8-CPT-cAMP also increased IP3R2, and this was reduced by actinomycin D. Analysis of the IP3R2 promoter revealed five CREs, and CREB potently increased promoter activity. Mutation of CRE4 or CRE5 decreased induction by CREB, and ChIP assay showed recruitment of CREB to these sites. Adenylyl cyclase (AC) 6 and 9 were the principal AC isoforms detected in rat hepatocytes, and silencing either one decreased organic anion secretion, which depends on IP3R2. Secretion furthermore was increased by overnight but not acute treatment with forskolin or 8-CPT-cAMP. These findings provide evidence that IP3R2 expression is transcriptionally regulated by cAMP via CREB binding to CRE elements in its promoter. The findings furthermore suggest that this mechanism is relevant for hormonal regulation of bile secretion.
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Affiliation(s)
- Emma Kruglov
- Digestive Diseases Section, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520-8019, USA
| | | | - Pedro Sousa
- Digestive Diseases Section, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520-8019, USA
| | - Jittima Weerachayaphorn
- Digestive Diseases Section, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520-8019, USA
| | - Mateus T Guerra
- Digestive Diseases Section, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520-8019, USA
| | - Michael H Nathanson
- Digestive Diseases Section, Yale School of Medicine, 333 Cedar Street, New Haven, CT 06520-8019, USA.
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13
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Taira Z, Ueda Y, Monmasu H, Yamase D, Miyake S, Shiraishi M. Characteristics of intracellular Ca 2+ signals consisting of two successive peaks in hepatocytes during liver regeneration after 70% partial hepatectomy in rats. J Exp Pharmacol 2016; 8:21-33. [PMID: 27757054 PMCID: PMC5055106 DOI: 10.2147/jep.s106084] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Two specific signals for regulating liver regeneration were found after 70% partial hepatectomy (PH) in rats. The first finding was a sustained increasing signal of intracellular Ca2+ ([Ca2+]i) in hepatocytes, consisting of two successive peaks with the first narrow peak at 1 hour and the second broad peak increasing by day 3 and then returning to normal by day 4. The second finding was an abnormal peak in the restoring ratio (Rr) curve of liver regeneration after 70% PH at day 4, where the Rr exceeded 100% temporarily, returned to a lower level, and then proceeded to a termination phase of liver regeneration. For 4 days around the two successive [Ca2+]i peaks and abnormal peak, various physiological activities were induced to promote liver regeneration after 70% PH. mRNA expression of genes encoding Ca2+-binding proteins S100A4 and calpain was induced between the two Ca2+ peaks. Hepatocytes underwent synchronous cell proliferation as the liver was restored from 30% to 70% at day 4, and significant expression of VEGF mRNA at around day 4 promoted angiogenesis to remodel the sinusoidal system. Cytochrome P450 activity levels in microsomes and alanine aminotransferase values at 24 hours after CCl4 administration were decreased after 70% PH, which recovered transiently to the control level at day 4, returned to the decreased level, and then slowly recovered by day 10. Thus, these results indicate that day 4 is important during liver regeneration after 70% PH.
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Affiliation(s)
- Zenei Taira
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Yukari Ueda
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Hiroshi Monmasu
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Daisuke Yamase
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Sayaka Miyake
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
| | - Maya Shiraishi
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan
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14
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Antony AN, Paillard M, Moffat C, Juskeviciute E, Correnti J, Bolon B, Rubin E, Csordás G, Seifert EL, Hoek JB, Hajnóczky G. MICU1 regulation of mitochondrial Ca(2+) uptake dictates survival and tissue regeneration. Nat Commun 2016; 7:10955. [PMID: 26956930 PMCID: PMC4786880 DOI: 10.1038/ncomms10955] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 02/03/2016] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial Ca2+ uptake through the recently discovered Mitochondrial Calcium Uniporter (MCU) is controlled by its gatekeeper Mitochondrial Calcium Uptake 1 (MICU1). However, the physiological and pathological role of MICU1 remains unclear. Here we show that MICU1 is vital for adaptation to postnatal life and for tissue repair after injury. MICU1 knockout is perinatally lethal in mice without causing gross anatomical defects. We used liver regeneration after partial hepatectomy as a physiological stress response model. Upon MICU1 loss, early priming is unaffected, but the pro-inflammatory phase does not resolve and liver regeneration fails, with impaired cell cycle entry and extensive necrosis. Ca2+ overload-induced mitochondrial permeability transition pore (PTP) opening is accelerated in MICU1-deficient hepatocytes. PTP inhibition prevents necrosis and rescues regeneration. Thus, our study identifies an unanticipated dependence of liver regeneration on MICU1 and highlights the importance of regulating MCU under stress conditions when the risk of Ca2+ overload is elevated. Mitochondrial calcium uptake is a highly regulated process, and calcium overload can lead to cell death. Here, using knockout mouse model, the authors show that the mitochondrial calcium uniporter (MCU) regulator MICU1 is needed to prevent calcium overload and promotes survival under liver regeneration and postnatal adaptation-associated stress.
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Affiliation(s)
- Anil Noronha Antony
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Melanie Paillard
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Cynthia Moffat
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Egle Juskeviciute
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Jason Correnti
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Brad Bolon
- Comparative Pathology and Mouse Phenotyping Shared Resource, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210, USA
| | - Emanuel Rubin
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - György Csordás
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Erin L Seifert
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - Jan B Hoek
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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15
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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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16
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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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17
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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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18
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Merlen G, Gentric G, Celton-Morizur S, Foretz M, Guidotti JE, Fauveau V, Leclerc J, Viollet B, Desdouets C. AMPKα1 controls hepatocyte proliferation independently of energy balance by regulating Cyclin A2 expression. J Hepatol 2014; 60:152-9. [PMID: 24012615 DOI: 10.1016/j.jhep.2013.08.025] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 08/27/2013] [Accepted: 08/30/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND AMP-activated protein kinase (AMPK) is an evolutionarily conserved sensor of cellular energy status that contributes to restoration of energy homeostasis by slowing down ATP-consuming pathways and activating ATP-producing pathways. Unexpectedly, in different systems, AMPK is also required for proper cell division. In the current study, we evaluated the potential effect of the AMPK catalytic subunit, AMPKα1, on hepatocyte proliferation. METHODS Hepatocyte proliferation was determined in AMPKα1 knockout and wild-type mice in vivo after two thirds partial hepatectomy, and in vitro in primary hepatocyte cultures. The activities of metabolic and cell cycle-related signaling pathways were measured. RESULTS After partial hepatectomy, hepatocytes proliferated rapidly, correlating with increased AMPK phosphorylation. Deletion of AMPKα1 delayed liver regeneration by impacting on G1/S transition phase. The proliferative defect of AMPKα1-deficient hepatocytes was cell autonomous, and independent of energy balance. The priming phase, lipid droplet accumulation, protein anabolic responses and growth factor activation after partial hepatectomy occurred normally in the absence of AMPKα1 activity. By contrast, mRNA and protein expression of cyclin A2, a key driver of S phase progression, were compromised in the absence of AMPK activity. Importantly, AMPKα1 controlled cyclin A2 transcription mainly through the ATF/CREB element. CONCLUSIONS Our study highlights a novel role for AMPKα1 as a positive regulator of hepatocyte division occurring independently of energy balance.
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Affiliation(s)
- Grégory Merlen
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR 8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Géraldine Gentric
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR 8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Séverine Celton-Morizur
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR 8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Marc Foretz
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR 8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Jacques-Emmanuel Guidotti
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR 8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Véronique Fauveau
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR 8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Jocelyne Leclerc
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR 8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Benoit Viollet
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR 8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Chantal Desdouets
- Inserm, U1016, Institut Cochin, Paris, France; CNRS, UMR 8104, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
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19
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Amaya MJ, Oliveira AG, Guimarães ES, Casteluber MCF, Carvalho SM, Andrade LM, Pinto MCX, Mennone A, Oliveira CA, Resende RR, Menezes GB, Nathanson MH, Leite MF. The insulin receptor translocates to the nucleus to regulate cell proliferation in liver. Hepatology 2014; 59:274-83. [PMID: 23839970 PMCID: PMC3823683 DOI: 10.1002/hep.26609] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 06/24/2013] [Indexed: 12/25/2022]
Abstract
UNLABELLED Insulin's metabolic effects in the liver are widely appreciated, but insulin's ability to act as a hepatic mitogen is less well understood. Because the insulin receptor (IR) can traffic to the nucleus, and Ca(2+) signals within the nucleus regulate cell proliferation, we investigated whether insulin's mitogenic effects result from activation of Ca(2+)-signaling pathways by IRs within the nucleus. Insulin-induced increases in Ca(2+) and cell proliferation depended upon clathrin- and caveolin-dependent translocation of the IR to the nucleus, as well as upon formation of inositol 1,4,5,-trisphosphate (InsP3) in the nucleus, whereas insulin's metabolic effects did not depend on either of these events. Moreover, liver regeneration after partial hepatectomy also depended upon the formation of InsP3 in the nucleus, but not the cytosol, whereas hepatic glucose metabolism was not affected by buffering InsP3 in the nucleus. CONCLUSION These findings provide evidence that insulin's mitogenic effects are mediated by a subpopulation of IRs that traffic to the nucleus to locally activate InsP3 -dependent Ca(2+)-signaling pathways. The steps along this signaling pathway reveal a number of potential targets for therapeutic modulation of liver growth in health and disease.
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Affiliation(s)
- Maria J. Amaya
- Section of Digestive Diseases, Department of Internal Medicine, Yale University. 333 Cedar Street. PO Box 208019. New Haven-CT, 06520-8019, USA
| | - André G. Oliveira
- Department of Physiology and Biophysics, Federal University of Minas Gerais. Av. Antônio Carlos, 6627. Belo Horizonte-Minas Gerais. CEP: 31270-901, Brazil
| | - Erika S. Guimarães
- Department of Physiology and Biophysics, Federal University of Minas Gerais. Av. Antônio Carlos, 6627. Belo Horizonte-Minas Gerais. CEP: 31270-901, Brazil
| | - Marisa C. F. Casteluber
- Department of Physiology and Biophysics, Federal University of Minas Gerais. Av. Antônio Carlos, 6627. Belo Horizonte-Minas Gerais. CEP: 31270-901, Brazil
| | - Sandhra M. Carvalho
- School of Engineering, Federal University of Minas Gerais, Av. Antônio Carlos, 6627. Belo Horizonte-Minas Gerais. CEP: 31270-901, Brazil
| | - Lidia M. Andrade
- Department of Physiology and Biophysics, Federal University of Minas Gerais. Av. Antônio Carlos, 6627. Belo Horizonte-Minas Gerais. CEP: 31270-901, Brazil,René Rachou Research Center, Oswaldo Cruz Foundation. Av. Augusto de Lima, 1715. Belo Horizonte-Minas Gerais. CEP: 30190-002, Brazil
| | - Mauro C. X. Pinto
- Department of Physiology and Biophysics, Federal University of Minas Gerais. Av. Antônio Carlos, 6627. Belo Horizonte-Minas Gerais. CEP: 31270-901, Brazil
| | - Albert Mennone
- Section of Digestive Diseases, Department of Internal Medicine, Yale University. 333 Cedar Street. PO Box 208019. New Haven-CT, 06520-8019, USA
| | - Cleida A. Oliveira
- Department of Morphology, Federal University of Minas Gerais. Av. Antônio Carlos, 6627. Belo Horizonte-Minas Gerais. CEP: 31270-901, Brazil
| | - Rodrigo R. Resende
- Department of Biochemistry and Immunology, Federal University of Minas Gerais. Av. Antônio Carlos, 6627. Belo Horizonte-Minas Gerais. CEP: 31270-901, Brazil
| | - Gustavo B. Menezes
- Department of Morphology, Federal University of Minas Gerais. Av. Antônio Carlos, 6627. Belo Horizonte-Minas Gerais. CEP: 31270-901, Brazil
| | - 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
| | - M. Fatima Leite
- Department of Physiology and Biophysics, Federal University of Minas Gerais. Av. Antônio Carlos, 6627. Belo Horizonte-Minas Gerais. CEP: 31270-901, Brazil,Howard Hughes Medical Institute
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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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21
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Melo CSB, Arantes Faria JAQ, Corrêa NCR, de Andrade C, Carvalho JL, Goes AM, Rodrigues MA, Gomes DA. Cytoplasmic-targeted parvalbumin blocks the proliferation of multipotent mesenchymal stromal cells in prophase. Stem Cell Res Ther 2013; 4:92. [PMID: 23928293 PMCID: PMC3854775 DOI: 10.1186/scrt291] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 08/02/2013] [Indexed: 02/01/2023] Open
Abstract
Introduction Multipotent mesenchymal stromal cells (MSCs) have gained considerable interest because of their potential use in the treatment of a variety of diseases and injuries. Although remarkable advancements have been made in clinical studies, substantial concerns still regard the safety of MSCs. Some evidence suggests that MSCs can spontaneously generate a population of cells with tumorigenic potential. Thus, studying the molecular mechanisms that control the proliferation of MSCs may be a necessary step toward the development of strategies for safe clinical practice. Ca2+ is a second messenger that mediates a wide range of cellular responses, including the regulation of cell proliferation, but little is known about its function in MSCs. The aim of this study was to investigate the effects of targeted Ca2+ buffering on MSCs proliferation in vitro. Methods Here, we used an adenoviral (Ad) vector encoding the Ca2+ chelator protein parvalbumin (PV) fused to a nuclear exclusion signal (NES) and the Discosoma red fluorescent protein (DsRed) to investigate the function of cytoplasmic Ca2+ signals on MSC proliferation. Confocal microscopy was used to demonstrate that PV-NES-DsRed was expressed in the cytoplasm. Ca2+ signaling was monitored by using Fluo-4-AM. Fluorescence-activated cell sorting (FACS) analysis of cells that were stained with propidium iodide was used as a quantitative measure of cell death. The mitotic index was assessed by immunofluorescence, and the expression of cyclins was examined with Western blot. Results Our results show that the Ad-PV-NES-DsRed fusion protein decreased serum-induced Ca2+ signaling and blocked the proliferation of rat adipose-derived MSCs (AT-MSCs) in prophase. FACS analysis revealed that Ad-PV-NES-DsRed did not induce cell death in AT-MSCs. Furthermore, Western blot analysis demonstrated that Ad-PV-NES-DsRed reduced extracellular signal-regulated kinase (Erk1/2) phosphorylation and cyclin B1 expression. Buffering cytosolic Ca2+ did not alter the expression of cyclins A/D1/D2/D3/E and E2. Conclusions Our results show that cytoplasmic Ca2+ signals are important for AT-MSCs progression beyond prophase because of their effects on Erk phosphorylation and cyclin B1 expression.
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22
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Sphingosine kinase-1 inhibition protects primary rat hepatocytes against bile salt-induced apoptosis. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1922-9. [PMID: 23816565 DOI: 10.1016/j.bbadis.2013.06.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 05/10/2013] [Accepted: 06/19/2013] [Indexed: 01/22/2023]
Abstract
Sphingosine kinases (SphKs) and their product sphingosine-1-phosphate (S1P) have been reported to regulate apoptosis and survival of liver cells. Cholestatic liver diseases are characterized by cytotoxic levels of bile salts inducing liver injury. It is unknown whether SphKs and/or S1P play a role in this pathogenic process. Here, we investigated the putative involvement of SphK1 and S1P in bile salt-induced cell death in hepatocytes. Primary rat hepatocytes were exposed to glycochenodeoxycholic acid (GCDCA) to induce apoptosis. GCDCA-exposed hepatocytes were co-treated with S1P, the SphK1 inhibitor Ski-II and/or specific antagonists of S1P receptors (S1PR1 and S1PR2). Apoptosis and necrosis were quantified. Ski-II significantly reduced GCDCA-induced apoptosis in hepatocytes (-70%, P<0.05) without inducing necrosis. GCDCA increased the S1P levels in hepatocytes (P<0.05). GCDCA induced [Ca(2+)] oscillations in hepatocytes and co-treatment with the [Ca(2+)] chelator BAPTA repressed GCDCA-induced apoptosis. Ski-II inhibited the GCDCA-induced intracellular [Ca(2+)] oscillations. Transcripts of all five S1P receptors were detected in hepatocytes, of which S1PR1 and S1PR2 appear most dominant. Inhibition of S1PR1, but not S1PR2, reduced GCDCA-induced apoptosis by 20%. Exogenous S1P also significantly reduced GCDCA-induced apoptosis (-50%, P<0.05), however, in contrast to the GCDCA-induced (intracellular) SphK1 pathway, this was dependent on S1PR2 and not S1PR1. Our results indicate that SphK1 plays a pivotal role in mediating bile salt-induced apoptosis in hepatocytes in part by interfering with intracellular [Ca(2+)] signaling and activation of S1PR1.
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Resende RR, Andrade LM, Oliveira AG, Guimarães ES, Guatimosim S, Leite MF. Nucleoplasmic calcium signaling and cell proliferation: calcium signaling in the nucleus. Cell Commun Signal 2013; 11:14. [PMID: 23433362 PMCID: PMC3599436 DOI: 10.1186/1478-811x-11-14] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 02/12/2013] [Indexed: 01/19/2023] Open
Abstract
Calcium (Ca2+) is an essential signal transduction element involved in the regulation of several cellular activities and it is required at various key stages of the cell cycle. Intracellular Ca2+ is crucial for the orderly cell cycle progression and plays a vital role in the regulation of cell proliferation. Recently, it was demonstrated by in vitro and in vivo studies that nucleoplasmic Ca2+ regulates cell growth. Even though the mechanism by which nuclear Ca2+ regulates cell proliferation is not completely understood, there are reports demonstrating that activation of tyrosine kinase receptors (RTKs) leads to translocation of RTKs to the nucleus to generate localized nuclear Ca2+ signaling which are believed to modulate cell proliferation. Moreover, nuclear Ca2+ regulates the expression of genes involved in cell growth. This review will describe the nuclear Ca2+ signaling machinery and its role in cell proliferation. Additionally, the potential role of nuclear Ca2+ as a target in cancer therapy will be discussed.
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Affiliation(s)
- Rodrigo R Resende
- Physiology and Biophysics, Federal University of Minas Gerais, 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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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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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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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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Abstract
Transgenic mice have had a tremendous impact on biomedical research. Most researchers are familiar with transgenic mice that carry Cre recombinase (Cre) and how they are used to create conditional knockouts. However, some researchers are less familiar with many of the other types of transgenic mice and their applications. For example, transgenic mice can be used to study biochemical and molecular pathways in primary cultures and cell suspensions derived from transgenic mice, cell-cell interactions using multiple fluorescent proteins in the same mouse, and the cell cycle in real time and in the whole animal, and they can be used to perform deep tissue imaging in the whole animal, follow cell lineage during development and disease, and isolate large quantities of a pure cell type directly from organs. These novel transgenic mice and their applications provide the means for studying of molecular and biochemical events in the whole animal that was previously limited to cell cultures. In conclusion, transgenic mice are not just for generating knockouts.
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Affiliation(s)
- R Lance Miller
- Epithelial Systems Biology Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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