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Brosch M, Kattler K, Herrmann A, von Schönfels W, Nordström K, Seehofer D, Damm G, Becker T, Zeissig S, Nehring S, Reichel F, Moser V, Thangapandi RV, Stickel F, Baretton G, Röcken C, Muders M, Matz-Soja M, Krawczak M, Gasparoni G, Hartmann H, Dahl A, Schafmayer C, Walter J, Hampe J. Epigenomic map of human liver reveals principles of zonated morphogenic and metabolic control. Nat Commun 2018; 9:4150. [PMID: 30297808 PMCID: PMC6175862 DOI: 10.1038/s41467-018-06611-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 09/14/2018] [Indexed: 12/21/2022] Open
Abstract
A deeper epigenomic understanding of spatial organization of cells in human tissues is an important challenge. Here we report the first combined positional analysis of transcriptomes and methylomes across three micro-dissected zones (pericentral, intermediate and periportal) of human liver. We identify pronounced anti-correlated transcriptional and methylation gradients including a core of 271 genes controlling zonated metabolic and morphogen networks and observe a prominent porto-central gradient of DNA methylation at binding sites of 46 transcription factors. The gradient includes an epigenetic and transcriptional Wnt signature supporting the concept of a pericentral hepatocyte regeneration pathway under steady-state conditions. While donors with non-alcoholic fatty liver disease show consistent gene expression differences corresponding to the severity of the disease across all zones, the relative zonated gene expression and DNA methylation patterns remain unchanged. Overall our data provide a wealth of new positional insights into zonal networks controlled by epigenetic and transcriptional gradients in human liver. Spatial mapping of genomic programs in tissue cells is an important step in the understanding of organ function and disease. Here, the authors provide a spatially resolved epigenomic and transcriptomic map of human liver and show porto-central gradients in metabolic and morphogen networks and transcription factor binding sites as a basis to better understand liver regeneration and function.
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Affiliation(s)
- Mario Brosch
- Medical Department 1, University Hospital Dresden, Technische Universität Dresden (TU Dresden), Dresden, Germany.,Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Kathrin Kattler
- Department of Genetics and Epigenetics, Universität des Saarlandes, Saarbrücken, Germany
| | - Alexander Herrmann
- Medical Department 1, University Hospital Dresden, Technische Universität Dresden (TU Dresden), Dresden, Germany.,Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Witigo von Schönfels
- Department of Visceral Surgery, University Hospital Schleswig-Holstein, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Karl Nordström
- Department of Genetics and Epigenetics, Universität des Saarlandes, Saarbrücken, Germany
| | - Daniel Seehofer
- Department of Hepatobiliary Surgery and Visceral Transplantation, University of Leipzig, Leipzig, Germany
| | - Georg Damm
- Department of Hepatobiliary Surgery and Visceral Transplantation, University of Leipzig, Leipzig, Germany
| | - Thomas Becker
- Department of Visceral Surgery, University Hospital Schleswig-Holstein, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Sebastian Zeissig
- Medical Department 1, University Hospital Dresden, Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Sophie Nehring
- Medical Department 1, University Hospital Dresden, Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Fabian Reichel
- Medical Department 1, University Hospital Dresden, Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Vincent Moser
- Medical Department 1, University Hospital Dresden, Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Raghavan Veera Thangapandi
- Medical Department 1, University Hospital Dresden, Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Felix Stickel
- Department of Gastroenterology, University of Zürich, Zürich, Switzerland
| | - Gustavo Baretton
- Institute of Pathology, University Hospital Dresden, Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Christoph Röcken
- Institute of Pathology, University Hospital Schleswig-Holstein, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Michael Muders
- Institute of Pathology, University Hospital Dresden, Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Madlen Matz-Soja
- Rudolf-Schönheimer-Institute for Biochemistry, University of Leipzig, Leipzig, Germany
| | - Michael Krawczak
- Institute of Medical Informatics and Statistics, Christian-Albrechts University, Kiel, Germany
| | - Gilles Gasparoni
- Department of Genetics and Epigenetics, Universität des Saarlandes, Saarbrücken, Germany
| | - Hella Hartmann
- Center for Molecular and Cellular Bioengineering (CMCB), Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Andreas Dahl
- Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden (TU Dresden), Dresden, Germany
| | - Clemens Schafmayer
- Department of Visceral Surgery, University Hospital Schleswig-Holstein, Christian-Albrechts-University Kiel, Kiel, Germany
| | - Jörn Walter
- Department of Genetics and Epigenetics, Universität des Saarlandes, Saarbrücken, Germany
| | - Jochen Hampe
- Medical Department 1, University Hospital Dresden, Technische Universität Dresden (TU Dresden), Dresden, Germany. .,Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden (TU Dresden), Dresden, Germany.
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Kietzmann T. Metabolic zonation of the liver: The oxygen gradient revisited. Redox Biol 2017; 11:622-630. [PMID: 28126520 PMCID: PMC5257182 DOI: 10.1016/j.redox.2017.01.012] [Citation(s) in RCA: 306] [Impact Index Per Article: 43.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 01/12/2017] [Accepted: 01/13/2017] [Indexed: 02/06/2023] Open
Abstract
The liver has a multitude of functions which are necessary to maintain whole body homeostasis. This requires that various metabolic pathways can run in parallel in the most efficient manner and that futile cycles are kept to a minimum. To a large extent this is achieved due to a functional specialization of the liver parenchyma known as metabolic zonation which is often lost in liver diseases. Although this phenomenon is known for about 40 years, the underlying regulatory pathways are not yet fully elucidated. The physiologically occurring oxygen gradient was considered to be crucial for the appearance of zonation; however, a number of reports during the last decade indicating that β-catenin signaling, and the hedgehog (Hh) pathway contribute to metabolic zonation may have shifted this view. In the current review we connect these new observations with the concept that the oxygen gradient within the liver acinus is a regulator of zonation. This is underlined by a number of facts showing that the β-catenin and the Hh pathway can be modulated by the hypoxia signaling system and the hypoxia-inducible transcription factors (HIFs). Altogether, we provide a view by which the dynamic interplay between all these pathways can drive liver zonation and thus contribute to its physiological function.
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Affiliation(s)
- Thomas Kietzmann
- Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, Oulu, Finland.
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3
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Berasain C, Avila MA. Regulation of hepatocyte identity and quiescence. Cell Mol Life Sci 2015; 72:3831-51. [PMID: 26089250 PMCID: PMC11114060 DOI: 10.1007/s00018-015-1970-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 05/23/2015] [Accepted: 06/12/2015] [Indexed: 12/11/2022]
Abstract
The liver is a highly differentiated organ with a central role in metabolism, detoxification and systemic homeostasis. To perform its multiple tasks, liver parenchymal cells, the hepatocytes, express a large complement of enabling genes defining their complex phenotype. This phenotype is progressively acquired during fetal development and needs to be maintained in adulthood to guarantee the individual's survival. Upon injury or loss of functional mass, the liver displays an extraordinary regenerative response, mainly based on the proliferation of hepatocytes which otherwise are long-lived quiescent cells. Increasing observations suggest that loss of hepatocellular differentiation and quiescence underlie liver malfunction in chronic liver disease and pave the way for hepatocellular carcinoma development. Here, we briefly review the essential mechanisms leading to the acquisition of liver maturity. We also identify the key molecular factors involved in the preservation of hepatocellular homeostasis and finally discuss potential strategies to preserve liver identity and function.
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Affiliation(s)
- Carmen Berasain
- Division of Hepatology, CIMA, University of Navarra, CIBEREHD, Instituto de Investigación Sanitaria de Navarra (IdiSNA), Avda. Pio XII, n55, 31008, Pamplona, Spain.
| | - Matías A Avila
- Division of Hepatology, CIMA, University of Navarra, CIBEREHD, Instituto de Investigación Sanitaria de Navarra (IdiSNA), Avda. Pio XII, n55, 31008, Pamplona, Spain.
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Oh IS, Park SH. Immune-mediated Liver Injury in Hepatitis B Virus Infection. Immune Netw 2015; 15:191-8. [PMID: 26330805 PMCID: PMC4553257 DOI: 10.4110/in.2015.15.4.191] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Revised: 07/26/2015] [Accepted: 08/02/2015] [Indexed: 12/29/2022] Open
Abstract
Hepatitis B virus (HBV) is responsible for approximately 350 million chronic infections worldwide and is a leading cause of broad-spectrum liver diseases such as hepatitis, cirrhosis and liver cancer. Although it has been well established that adaptive immunity plays a critical role in viral clearance, the pathogenetic mechanisms that cause liver damage during acute and chronic HBV infection remain largely known. This review describes our current knowledge of the immune-mediated pathogenesis of HBV infection and the role of immune cells in the liver injury during hepatitis B.
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Affiliation(s)
- In Soo Oh
- Laboratory of Immunology and Infectious Diseases, Graduate School of Medical Science and Engineering, KAIST, Daejeon 34141, Korea. ; Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul 06973, Korea
| | - Su-Hyung Park
- Laboratory of Translational Immunology and Vaccinology, Graduate School of Medical Science and Engineering, KAIST, Daejeon 34141, Korea
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Schleicher J, Tokarski C, Marbach E, Matz-Soja M, Zellmer S, Gebhardt R, Schuster S. Zonation of hepatic fatty acid metabolism - The diversity of its regulation and the benefit of modeling. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:641-56. [PMID: 25677822 DOI: 10.1016/j.bbalip.2015.02.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 01/26/2015] [Accepted: 02/03/2015] [Indexed: 02/07/2023]
Abstract
A pronounced heterogeneity between hepatocytes in subcellular structure and enzyme activities was discovered more than 50years ago and initiated the idea of metabolic zonation. In the last decades zonation patterns of liver metabolism were extensively investigated for carbohydrate, nitrogen and lipid metabolism. The present review focuses on zonation patterns of the latter. We review recent findings regarding the zonation of fatty acid uptake and oxidation, ketogenesis, triglyceride synthesis and secretion, de novo lipogenesis, as well as bile acid and cholesterol metabolism. In doing so, we expose knowledge gaps and discuss contradictory experimental results, for example on the zonation pattern of fatty acid oxidation and de novo lipogenesis. Thus, possible rewarding directions of further research are identified. Furthermore, recent findings about the regulation of metabolic zonation are summarized, especially regarding the role of hormones, nerve innervation, morphogens, gender differences and the influence of the circadian clock. In the last part of the review, a short collection of models considering hepatic lipid metabolism is provided. We conclude that modeling, despite its proven benefit for understanding of hepatic carbohydrate and ammonia metabolisms, has so far been largely disregarded in the study of lipid metabolism; therefore some possible fields of modeling interest are presented.
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Affiliation(s)
- J Schleicher
- Department of Bioinformatics, University of Jena, Jena, Germany.
| | - C Tokarski
- Department of Bioinformatics, University of Jena, Jena, Germany
| | - E Marbach
- Institute of Biochemistry, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - M Matz-Soja
- Institute of Biochemistry, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - S Zellmer
- Department of Chemicals and Product Safety, German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - R Gebhardt
- Institute of Biochemistry, Faculty of Medicine, University of Leipzig, Leipzig, Germany
| | - S Schuster
- Department of Bioinformatics, University of Jena, Jena, Germany
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Hijmans BS, Grefhorst A, Oosterveer MH, Groen AK. Zonation of glucose and fatty acid metabolism in the liver: mechanism and metabolic consequences. Biochimie 2013; 96:121-9. [PMID: 23792151 DOI: 10.1016/j.biochi.2013.06.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Accepted: 06/12/2013] [Indexed: 12/13/2022]
Abstract
The liver is generally considered as a relatively homogeneous organ containing four different cell types. It is however well-known that the liver is not homogeneous and consists of clearly demarcated metabolic zones. Hepatocytes from different zones show phenotypical heterogeneity in metabolic features, leading to zonation of metabolic processes across the liver acinus. Zonation of processes involved in glucose and fatty acid metabolism is rather flexible and therefore prone to change under (patho)physiological conditions. Hepatic zonation appears to play an important role in the segregation of the different metabolic pathways in the liver. As a consequence, perturbations in metabolic zonation may be a part of metabolic liver diseases. The metabolic syndrome is characterized by the inability of insulin to adequately suppress hepatic gluconeogenesis, leading to hyperglycemia, hyperinsulinemia and eventually to type II diabetes. As insulin promotes lipogenesis through the transcription factor sterol regulatory element binding protein (SREBP)-1c, one would expect that lipogenesis should also be impaired in insulin-resistant states. However, in the metabolic syndrome hepatic de novo lipogenesis is increased, leading to hyperlipidemia and hepatosteatosis, primarily in the pericentral zone. These observations suggest the co-existence of insulin resistant glucose metabolism and insulin sensitive lipid metabolism in the metabolic syndrome. Here we provide a theoretical framework to explain this so-called 'insulin signaling paradox' in the context of metabolic zonation of the liver.
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Affiliation(s)
- Brenda S Hijmans
- Departments of Pediatrics and Laboratory Medicine, University of Groningen, University Medical Center Groningen, The Netherlands.
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Rawat S, Clippinger AJ, Bouchard MJ. Modulation of apoptotic signaling by the hepatitis B virus X protein. Viruses 2012; 4:2945-72. [PMID: 23202511 PMCID: PMC3509679 DOI: 10.3390/v4112945] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 10/23/2012] [Accepted: 10/31/2012] [Indexed: 12/18/2022] Open
Abstract
Worldwide, an estimated 350 million people are chronically infected with the Hepatitis B Virus (HBV); chronic infection with HBV is associated with the development of severe liver diseases including hepatitis and cirrhosis. Individuals who are chronically infected with HBV also have a significantly higher risk of developing hepatocellular carcinoma (HCC) than uninfected individuals. The HBV X protein (HBx) is a key regulatory HBV protein that is important for HBV replication, and likely plays a cofactor role in the development of HCC in chronically HBV-infected individuals. Although some of the functions of HBx that may contribute to the development of HCC have been characterized, many HBx activities, and their putative roles during the development of HBV-associated HCC, remain incompletely understood. HBx is a multifunctional protein that localizes to the cytoplasm, nucleus, and mitochondria of HBV‑infected hepatocytes. HBx regulates numerous cellular signal transduction pathways and transcription factors as well as cell cycle progression and apoptosis. In this review, we will summarize reports in which the impact of HBx expression on cellular apoptotic pathways has been analyzed. Although various effects of HBx on apoptotic pathways have been observed in different model systems, studies of HBx activities in biologically relevant hepatocyte systems have begun to clarify apoptotic effects of HBx and suggest mechanisms that could link HBx modulation of apoptotic pathways to the development of HBV-associated HCC.
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Affiliation(s)
- Siddhartha Rawat
- Graduate Program in Molecular and Cellular Biology and Genetics, Drexel University College of Medicine, Philadelphia, PA 19102, USA;
| | - Amy J. Clippinger
- Department of Cancer Biology, Abramson Family Cancer Research Institute, School of Medicine, University of Pennsylvania Philadelphia, PA 19104, USA;
| | - Michael J. Bouchard
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
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LeCluyse EL, Witek RP, Andersen ME, Powers MJ. Organotypic liver culture models: meeting current challenges in toxicity testing. Crit Rev Toxicol 2012; 42:501-48. [PMID: 22582993 PMCID: PMC3423873 DOI: 10.3109/10408444.2012.682115] [Citation(s) in RCA: 239] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Revised: 03/26/2012] [Accepted: 03/30/2012] [Indexed: 02/07/2023]
Abstract
Prediction of chemical-induced hepatotoxicity in humans from in vitro data continues to be a significant challenge for the pharmaceutical and chemical industries. Generally, conventional in vitro hepatic model systems (i.e. 2-D static monocultures of primary or immortalized hepatocytes) are limited by their inability to maintain histotypic and phenotypic characteristics over time in culture, including stable expression of clearance and bioactivation pathways, as well as complex adaptive responses to chemical exposure. These systems are less than ideal for longer-term toxicity evaluations and elucidation of key cellular and molecular events involved in primary and secondary adaptation to chemical exposure, or for identification of important mediators of inflammation, proliferation and apoptosis. Progress in implementing a more effective strategy for in vitro-in vivo extrapolation and human risk assessment depends on significant advances in tissue culture technology and increasing their level of biological complexity. This article describes the current and ongoing need for more relevant, organotypic in vitro surrogate systems of human liver and recent efforts to recreate the multicellular architecture and hemodynamic properties of the liver using novel culture platforms. As these systems become more widely used for chemical and drug toxicity testing, there will be a corresponding need to establish standardized testing conditions, endpoint analyses and acceptance criteria. In the future, a balanced approach between sample throughput and biological relevance should provide better in vitro tools that are complementary with animal testing and assist in conducting more predictive human risk assessment.
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Affiliation(s)
- Edward L LeCluyse
- The Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, Research Triangle Park, NC, USA.
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Bierwolf J, Lutgehetmann M, Deichmann S, Erbes J, Volz T, Dandri M, Cohen S, Nashan B, Pollok JM. Primary Human Hepatocytes from Metabolic-Disordered Children Recreate Highly Differentiated Liver-Tissue-Like Spheroids on Alginate Scaffolds. Tissue Eng Part A 2012; 18:1443-53. [DOI: 10.1089/ten.tea.2012.0029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Jeanette Bierwolf
- Department of Hepatobiliary and Transplant Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Marc Lutgehetmann
- Department of Internal Medicine 1, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Institute of Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Steffen Deichmann
- Department of Hepatobiliary and Transplant Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Johannes Erbes
- Department of Hepatobiliary and Transplant Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tassilo Volz
- Department of Internal Medicine 1, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Maura Dandri
- Department of Internal Medicine 1, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Smadar Cohen
- Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Bjoern Nashan
- Department of Hepatobiliary and Transplant Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Joerg-Matthias Pollok
- Department of Hepatobiliary and Transplant Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Torre C, Perret C, Colnot S. Molecular determinants of liver zonation. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 97:127-50. [PMID: 21074732 DOI: 10.1016/b978-0-12-385233-5.00005-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The phenomenon of "liver zonation" is a remarkable process by which the liver fulfills its metabolic functions, involving highly dynamic transcriptional mechanisms. Its understanding is therefore a challenging issue. Zonation is reflected in heterogeneity of hepatocytes along the porto-central axis of the liver: periportal hepatocytes, located in the vicinity of the afferent portal vein, do not express the same metabolic enzymes than pericentral hepatocytes located near the efferent central vein. This is mainly dictated at the transcriptional level by specific pericentral versus periportal genetic programs. The mechanisms by which zonation is established have been extensively investigated since its initial discovery 40 years ago. The discovery in 2006 that Wnt/β-catenin pericentral signaling was a master regulator of this complex liver topology has been a major breakthrough. A major current priority in the field is the integration of the β-catenin pathway with other determinants that govern zonation of the liver.
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Affiliation(s)
- Cyril Torre
- Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), Paris, France
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Lozoya OA, Wauthier E, Turner RA, Barbier C, Prestwich GD, Guilak F, Superfine R, Lubkin SR, Reid LM. Regulation of hepatic stem/progenitor phenotype by microenvironment stiffness in hydrogel models of the human liver stem cell niche. Biomaterials 2011; 32:7389-402. [PMID: 21788068 DOI: 10.1016/j.biomaterials.2011.06.042] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 06/20/2011] [Indexed: 02/09/2023]
Abstract
Human livers have maturational lineages of cells within liver acini, beginning periportally in stem cell niches, the canals of Hering, and ending in polyploid hepatocytes pericentrally and cholangiocytes in bile ducts. Hepatic stem cells (hHpSCs) in vivo are partnered with mesenchymal precursors to endothelia (angioblasts) and stellate cells, and reside in regulated microenvironments, stem cell niches, containing hyaluronans (HA). The in vivo hHpSC niche is modeled in vitro by growing hHpSC in two-dimensional (2D) cultures on plastic. We investigated effects of 3D microenvironments, mimicking the liver's stem cell niche, on these hHpSCs by embedding them in HA-based hydrogels prepared with Kubota's Medium (KM), a serum-free medium tailored for endodermal stem/progenitors. The KM-HA hydrogels mimicked the niches, matched diffusivity of culture medium, exhibited shear thinning and perfect elasticity under mechanical loading, and had predictable stiffness depending on their chemistry. KM-HA hydrogels, which supported cell attachment, survival and expansion of hHpSC colonies, induced transition of hHpSC colonies towards stable heterogeneous populations of hepatic progenitors depending on KM-HA hydrogel stiffness, as shown by both their gene and protein expression profile. These acquired phenotypes did not show morphological evidence of fibrotic responses. In conclusion, this study shows that the mechanical properties of the microenvironment can regulate differentiation in endodermal stem cell populations.
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Affiliation(s)
- Oswaldo A Lozoya
- Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC and UNC School of Medicine, Chapel Hill, NC 27599, USA
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Bierwolf J, Lutgehetmann M, Feng K, Erbes J, Deichmann S, Toronyi E, Stieglitz C, Nashan B, Ma PX, Pollok JM. Primary rat hepatocyte culture on 3D nanofibrous polymer scaffolds for toxicology and pharmaceutical research. Biotechnol Bioeng 2010; 108:141-50. [DOI: 10.1002/bit.22924] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Abstract
The Ashwell-Morell receptor (AMR) of hepatocytes, originally termed the hepatic asialoglycoprotein receptor, was the first cellular receptor to be identified and isolated and the first lectin to be detected in mammals. It is one of the multiple lectins of the C-type lectin family involved in recognition, binding, and clearance of asialoglycoproteins. We recently identified endogenous ligands of the AMR as desialylated prothrombotic components, including platelets and von Willebrand Factor [Ellies L. G., Ditto D., Levy G. G., Wahrenbrock M., Ginsburg D., Varki A., Le D. T., and Marth J. D. (2002). Sialyltransferase ST3Gal-IV operates as a dominant modifier of hemostasis by concealing asialoglycoprotein receptor ligands. Proc. Natl. Acad. Sci. USA 99: pp. 10042-10047; Grewal, P. K. Uchiyama, S., Ditto, D., Varki, N., Le, D. T., Nizet, V., Marth, J. D. (2008). The Ashwell receptor mitigates the lethal coagulopathy of sepsis. Nat. Medicine 14, pp. 648-655]. Among these components, clearance by the liver's AMR is enhanced by exposure of terminal galactose on the glycan chains. A physiological role for engaging the AMR in rapid clearance was identified as mitigating disseminating intravascular coagulopathy in sepsis to promote survival. This chapter overviews the endogenous ligands of the AMR as components of the coagulatory system, describes clearance mechanisms of the liver, and details hematology and coagulation assays used in mouse coagulation studies.
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Colletti M, Cicchini C, Conigliaro A, Santangelo L, Alonzi T, Pasquini E, Tripodi M, Amicone L. Convergence of Wnt signaling on the HNF4alpha-driven transcription in controlling liver zonation. Gastroenterology 2009; 137:660-72. [PMID: 19454287 DOI: 10.1053/j.gastro.2009.05.038] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 05/10/2009] [Accepted: 05/11/2009] [Indexed: 12/23/2022]
Abstract
BACKGROUND & AIMS In each hepatocyte, the specific repertoire of gene expression is influenced by its exact location along the portocentrovenular axis of the hepatic lobule and provides a reason for the liver functions compartmentalization defined "metabolic zonation." So far, few molecular players controlling genetic programs of periportal (PP) and perivenular (PV) hepatocytes have been identified; the elucidation of zonation mechanisms remains a challenge for experimental hepatology. Recently, a key role in induction and maintenance of the hepatocyte heterogeneity has been ascribed to Wnt/beta-catenin pathway. We sought to clarify how this wide-ranging stimulus integrates with hepatocyte specificity. METHODS Reverse transcriptase polymerase chain reaction (RT-PCR) allowed the transcriptional profiling of hepatocytes derived from in vitro differentiation of liver stem cells. The GSK3beta inhibitor 6-bromoindirubin-3'-oxime (BIO) was used for beta-catenin stabilization. Co-immunoprecipitations were used to study biochemical protein interactions while ChIP assays allowed the in vivo inspection of PV and PP genes regulatory regions. RESULTS We found that spontaneous differentiation of liver stem cells gives rise to PP hepatocytes that, after Wnt pathway activation, switch into PV hepatocytes. Next, we showed that the Wnt downstream player LEF1 interacts with the liver-enriched transcriptional factor HNF4alpha. Finally, we unveiled that the BIO induced activation of PV genes correlates with LEF1 binding to both its own and HNF4alpha consensus, and the repression of PP genes correlates with HNF4alpha displacement from its own consensus. CONCLUSION Our data show a direct and hitherto unknown convergence of the canonical Wnt signaling on the HNF4alpha-driven transcription providing evidences of a mechanism controlling liver zonated gene expression.
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Affiliation(s)
- Marta Colletti
- Department of Cellular Biotechnologies and Haematology, Istituto Pasteur-Fondazione Cenci Bolognetti, University Sapienza of Rome, Italy
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Hepatitis B virus X protein modulates apoptosis in primary rat hepatocytes by regulating both NF-kappaB and the mitochondrial permeability transition pore. J Virol 2009; 83:4718-31. [PMID: 19279112 DOI: 10.1128/jvi.02590-08] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The hepatitis B virus (HBV) X protein (HBx) is a multifunctional protein that regulates numerous cellular signal transduction pathways, including those that modulate apoptosis. However, different HBx-dependent effects on apoptosis have been reported; these differences are likely the consequence of the exact conditions and cell types used in a study. Many of the previously reported studies that analyzed HBx regulation of apoptosis were conducted in immortalized or transformed cells, and the alterations that have transformed or immortalized these cells likely impact apoptotic pathways. We examined the effects of HBx on apoptotic pathways in cultured primary rat hepatocytes, a biologically relevant system that mimics normal hepatocytes in the liver. We analyzed the effects of HBx on apoptosis both when HBx was expressed in the absence of other HBV proteins and in the context of HBV replication. HBx stimulation of NF-kappaB inhibited the activation of apoptotic pathways in cultured primary rat hepatocytes. However, when HBx-induced activation of NF-kappaB was blocked, HBx stimulated apoptosis; blocking the activity of the mitochondrial permeability transition pore inhibited HBx activation of apoptosis. These results suggest that HBx can be either proapoptotic or antiapoptotic in hepatocytes, depending on the status of NF-kappaB, and confirm previous studies that link some HBx activities to modulation of the mitochondrial permeability transition pore. Overall, our studies define apoptotic pathways that are regulated by HBx in cultured primary hepatocytes and provide potential mechanisms for the development of HBV-associated liver cancer.
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17
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Wang J, Olin M, Rozell B, Björkhem I, Einarsson C, Eggertsen G, Gåfvels M. Differential hepatocellular zonation pattern of cholesterol 7α-hydroxylase (Cyp7a1) and sterol 12α-hydroxylase (Cyp8b1) in the mouse. Histochem Cell Biol 2007; 127:253-61. [PMID: 17237956 DOI: 10.1007/s00418-006-0239-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2006] [Indexed: 12/13/2022]
Abstract
The synthesis of primary bile acids is confined to the hepatocytes. This study aimed to evaluate the expression pattern within the liver architecture of the rate-limiting enzyme of the neutral pathway, cholesterol 7alpha-hydroxylase (Cyp7a1), and sterol 12alpha-hydroxylase (Cyp8b1), the enzyme necessary for the synthesis of cholic acid. Specific Cyp8b1 and Cyp7a1 peptide antiserums were used for immunohistochemical staining of livers from wild type and Cyp8b1 null mice, the latter instead expressing beta-galactosidase (beta-Gal) as a replacement reporter gene. Cyp8b1 was mainly expressed in the hepatocytes in a zonal pattern surrounding the central vein while the areas surrounding the portal zones showed much lower levels. The zonation was maintained in cholic acid-depleted mice using beta-Gal as a reporter protein. Cyp7a1 expression in wild type mice also showed a zonal distribution pattern, although less distinct, with a maximal expression within a 1-2 cell thick layer of hepatocytes surrounding the central vein. In Cyp8b1 null mice, a more intense staining was obtained, in accordance with the higher expression level of Cyp7a1, although the overall expression pattern was maintained. Our results in mice indicate possible differences in the regulation of the cellular zonation of Cyp7a1 and Cyp8b1. Also, cholic acid affects the set-point of Cyp7a1 expression but not its zonal distribution.
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Affiliation(s)
- Jin Wang
- Department of Laboratory Medicine (H3), Division of Clinical Chemistry, C1-74, Karolinska Institutet and Karolinska University Hospital, 141 86 Stockholm, Sweden
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18
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Benhamouche S, Decaens T, Godard C, Chambrey R, Rickman DS, Moinard C, Vasseur-Cognet M, Kuo CJ, Kahn A, Perret C, Colnot S. Apc tumor suppressor gene is the "zonation-keeper" of mouse liver. Dev Cell 2006; 10:759-70. [PMID: 16740478 DOI: 10.1016/j.devcel.2006.03.015] [Citation(s) in RCA: 382] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 03/08/2006] [Accepted: 03/23/2006] [Indexed: 12/26/2022]
Abstract
The molecular mechanisms by which liver genes are differentially expressed along a portocentral axis, allowing for metabolic zonation, are poorly understood. We provide here compelling evidence that the Wnt/beta-catenin pathway plays a key role in liver zonation. First, we show the complementary localization of activated beta-catenin in the perivenous area and the negative regulator Apc in periportal hepatocytes. We then analyzed the immediate consequences of either a liver-inducible Apc disruption or a blockade of Wnt signaling after infection with an adenovirus encoding Dkk1, and we show that Wnt/beta-catenin signaling inversely controls the perivenous and periportal genetic programs. Finally, we show that genes involved in the periportal urea cycle and the perivenous glutamine synthesis systems are critical targets of beta-catenin signaling, and that perturbations to ammonia metabolism are likely responsible for the death of mice with liver-targeted Apc loss. From our results, we propose that Apc is the liver "zonation-keeper" gene.
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Affiliation(s)
- Samira Benhamouche
- Institut Cochin, Département GDPM, INSERM U567, CNRS, UMR-S 8104, Paris, F-75014, France
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19
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Nyirenda MJ, Dean S, Lyons V, Chapman KE, Seckl JR. Prenatal programming of hepatocyte nuclear factor 4alpha in the rat: A key mechanism in the 'foetal origins of hyperglycaemia'? Diabetologia 2006; 49:1412-20. [PMID: 16570165 DOI: 10.1007/s00125-006-0188-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2005] [Accepted: 12/02/2005] [Indexed: 11/27/2022]
Abstract
AIMS/HYPOTHESIS Prenatal glucocorticoid exposure causes lifelong hyperglycaemia in rat offspring, associated with permanently increased hepatic phosphoenolpyruvate carboxykinase 2 (PCK2), the rate-controlling enzyme of gluconeogenesis. To elucidate the mechanisms underlying the 'programming' of PCK2, this study examined the effect of prenatal dexamethasone treatment on expression of transcription factors that regulate Pck2. MATERIALS AND METHODS Real-time RT-PCR and in situ hybridisation were used to measure and localise hepatic mRNA transcribed from the genes for PCK2, hepatocyte nuclear factor 4, alpha (HNF4A), transcription factor 1 (TCF1), CCAAT/enhancer binding protein, alpha (CEBPA), CEBPB, the glucocorticoid receptor (NR3C1) and peroxisome proliferative activated receptor, gamma, coactivator 1 alpha (PPARGC1A) in foetal and adult offspring of dams treated with dexamethasone or vehicle during the last week of gestation. RESULTS Prenatal dexamethasone exposure significantly elevated Hnf4a mRNA expression in foetal and adult liver. This resulted from increased expression of isoforms derived from the 'adult' (P1) Hnf4a promoter. In contrast, isoforms from the 'foetal' (P2) promoter were markedly suppressed by dexamethasone. Like Pck2, the increase in hepatic Hnf4a mRNA occurred exclusively in the periportal zone. Foetal Tcf1 expression was also increased by dexamethasone treatment, but this did not persist into adulthood. Prenatal dexamethasone did not affect the amounts of foetal and/or adult Cebpa, Cebpb, Nr3c1 or Ppargc1a mRNA. CONCLUSIONS/INTERPRETATION Prenatal dexamethasone exposure caused a permanent increase in hepatic Hnf4a mRNA. This increase, which was associated with a premature switch from foetal to adult promoter predominance, was congruent with changes in Pck2 expression. These data suggest that HNF4A might mediate Pck2 overexpression and subsequent hyperglycaemia.
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Affiliation(s)
- M J Nyirenda
- Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
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20
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Malarkey DE, Johnson K, Ryan L, Boorman G, Maronpot RR. New insights into functional aspects of liver morphology. Toxicol Pathol 2005; 33:27-34. [PMID: 15805053 DOI: 10.1080/01926230590881826] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The liver is structurally and functionally complex and has been considered second only to brain in its complexity. Many mysteries still exist in this heterogeneous tissue whose functional unit of the lobule has continued to stump morphologists for over 300 years. The primary lobule, proposed by Matsumoto in 1979, has been gaining acceptance as the functional unit of the liver over other conceptual views because it's based on vessel architecture and includes the classic lobule as a secondary feature. Although hepatocytes comprise almost 80% of the liver, there are at least another dozen cell types, many of which provide "cross-talk" and play important functional roles in the normal and diseased liver. The distribution and functional roles of all cells in the liver must be carefully considered in both the analysis and interpretation of research data, particularly data in the area of genomics and "phenotypic anchoring" of gene expression results. Discoveries regarding the functional heterogeneity of the various liver cell types, including hepatocytes, hepatic stellate cells, sinusoidal endothelia, and Kupffer cells, are providing new insights into our understanding of the development, prevention and treatment of liver disease. For example, functional differences along zonal patterns (centrilobular or periportal) have been demonstrated for sinusoidal endothelium, Kupffer cells, and hepatocytes and can explain the gradients and manifestations of disease observed within lobules. Intralobular gradients of bile uptake, glycogen depletion, glutamine synthetase, and carboxylesterase by hepatocytes; widened fenestrations in centrilobular sinusoidal lining cells; and differences in the components of centrilobular extracellular matrix or function of Kupffer cells have been demonstrated. Awareness of the complexities and heterogeneity of the liver will add to a greater understanding of liver function and disease processes that lead to toxicity, cancer, and other diseases.
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Affiliation(s)
- David E Malarkey
- National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
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21
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Roth U, Jungermann K, Kietzmann T. Modulation of glucokinase expression by hypoxia-inducible factor 1 and upstream stimulatory factor 2 in primary rat hepatocytes. Biol Chem 2004; 385:239-47. [PMID: 15134337 DOI: 10.1515/bc.2004.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Glucokinase (GK) is the key enzyme of glucose utilization in liver and is localized in the less aerobic perivenous area. Until now, the O2-responsive elements in the liver-specific GK promoter are unknown, and therefore the aim of this study was to identify the O2-responsive element in this promoter. We found that the GK promoter sequence -87/-80 matched the binding site for hypoxia inducible factor 1 (HIF-1) and upstream stimulatory factor (USF). In primary rat hepatocytes we could show that venous pO2 enhanced HIF-1alpha and USF-2a levels, both of which activated GK expression. Furthermore, transfection experiments revealed that the GK sequence -87/-80 mediated the HIF-1alpha- or USF-2-dependent activation of the GK promoter. The binding of HIF-1 and USF to the GK-HRE was corroborated by electrophoretic mobility shift assay (EMSA). However, the maximal response to HIF-1alpha or USF was only achieved when constructs with the -87/-80 sequence in context with a 3'-36 bp native GK promoter sequence containing a hepatocyte nuclear factor 4 (HNF-4) binding site were used. HIF-1alpha and HNF-4 additively activated the GK promoter, while USF-2 and HNF-4 together did not show this additive activation. Thus, HIF-1 and USF may play differential roles in the modulation of GK expression in response to O2.
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Affiliation(s)
- Ulrike Roth
- Institut für Biochemie und Molekulare Zellbiologie, Georg-August-Universität, Humboldtallee 23, D-37073 Göttingen, Germany
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22
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Kang S, Spann NJ, Hui TY, Davis RA. ARP-1/COUP-TF II determines hepatoma phenotype by acting as both a transcriptional repressor of microsomal triglyceride transfer protein and an inducer of CYP7A1. J Biol Chem 2003; 278:30478-86. [PMID: 12777384 DOI: 10.1074/jbc.m304201200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
L35 and FAO cells were derived as single cell isolates from H35 cells. Whereas L35 cells do not express microsomal triglyceride transfer protein (MTP), which regulates lipoprotein secretion, they express CYP7A1, which regulates bile acid synthesis from cholesterol. FAO cells display the opposite phenotype (i.e. expression of MTP but not CYP7A1). We examined the molecular basis of the transcriptional inactivation of the MTP gene in L35 cells. Nested deletion and mutagenesis studies show that a conserved DR1 element within the 135-bp proximal MTP promoter is responsible for differential expression by L35 and FAO cells. Yeast one-hybrid screening identified apolipoprotein A1 regulatory protein-1/chicken ovalbumin upstream promoter transcription factor II (ARP-1/COUP-TFII) and retinoid X receptor (RXRalpha) as the protein factors that can bind to the conserved DR1 element. Nuclear extracts from L35 cells contained 2-fold more ARP-1/COUP-TFII and 50% less RXRalpha than those from FAO cells. Immunologic studies show that in L35 cells, ARP-1/COUP-TFII is bound to the DR1 element, whereas in FAO cells, a complex containing RXRalpha is bound to the DR1 element. Co-transfection studies show that ARP-1/COUP-TFII repressed MTP promoter activity by approximately 70% in FAO hepatoma cells, whereas RXRalpha and its ligand 9-cis-retinoic acid increased MTP promoter activity by 6-fold in L35 cells. The combined data suggest that in the context of the MTP promoter, ARP-1/COUP-TFII (repressor) and a complex containing RXRalpha (inducer) compete for the DR1 element. Analysis of the CYP7A1 promoter revealed that it is approximately 5-fold more active in L35 cells than in FAO cells. Co-transfection of an ARP-1/COUP-TFII expression vector showed that it enhances CYP7A1 promoter activity by 6-fold in FAO cells. These combined findings indicate that ARP-1/COUP-TFII acts as both a transcriptional repressor (of MTP) and as a transcription activator (of CYP7A1). This dual function of ARP-1/COUP-TFII may play an important role in determining the metabolic phenotype of individual liver cells.
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Affiliation(s)
- Sohye Kang
- Mammalian Cell and Molecular Biology Laboratory, Department of Biology, Molecular Biology Institute, San Diego State University, San Diego, California 92182-4614, USA
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23
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Roth U, Jungermann K, Kietzmann T. Activation of glucokinase gene expression by hepatic nuclear factor 4alpha in primary hepatocytes. Biochem J 2002; 365:223-8. [PMID: 11950391 PMCID: PMC1222650 DOI: 10.1042/bj20020340] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2002] [Revised: 04/04/2002] [Accepted: 04/12/2002] [Indexed: 12/19/2022]
Abstract
Glucokinase (GK) is a key enzyme for glucose utilization in liver and shows a higher expression in the perivenous zone. In primary rat hepatocytes, the GK gene expression was activated by HNF (hepatic nuclear factor)-4alpha via the sequence -52/-39 of the GK promoter. Venous pO2 enhanced HNF-4 levels and HNF-4 binding to the GK-HNF-4 element. Thus, HNF-4alpha could play the role of a regulator for zonated GK expression.
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Affiliation(s)
- Ulrike Roth
- Institut für Biochemie und Molekulare Zellbiologie, Georg-August-Universität Göttingen, Humboldtallee 23, D-37073 Göttingen, Germany
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24
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Vanhaecke T, Lindros KO, Oinonen T, Coecke S, DeBast G, Phillips IR, Shephard EA, Vercruysse A, Rogiers V. Effect of ethanol on the expression of hepatic glutathione S-transferase: an in vivo/in vitro study. Biochem Pharmacol 2000; 60:1491-6. [PMID: 11020451 DOI: 10.1016/s0006-2952(00)00446-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ethanol, a human toxicant and a solvent in pharmacological research, is known to interfere with biotransformation of xenobiotics. We compared the in vivo and in vitro long-term effects of ethanol exposure on the expression of glutathione S-transferases (GST, EC 2. 5.1.18) in rat liver. Long-term in vivo ethanol treatment to achieve blood ethanol levels ranging between 10-50 mM was by liquid diet feeding. For in vitro experiments, rat hepatocytes co-cultured with rat liver epithelial cells were exposed to 17 and 68 mM ethanol for up to 10 days. Two weeks of liquid diet ethanol treatment increased total GST activity. Both Mu and Alpha classes and in particular the A1 and A2 subunits and the amount of their corresponding mRNAs were increased. Total GST activity was also increased in co-cultures after exposure to 68 mM ethanol for 10 days. However, the Mu class subunits M1 and M2 and the corresponding mRNAs were increased, rather than the Alpha class subunits. Thus, long-term exposure to ethanol induces hepatic GST both in vivo and in vitro, but different isoenzymes are affected. Consequently, extrapolation of in vitro data on GST expression and regulation to the in vivo situation must be judicious. During xenobiotic metabolism in cell culture, a shift in relative expression and induction of different GST forms may occur, resulting in either an under- or overestimation of effects.
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Affiliation(s)
- T Vanhaecke
- Department of Toxicology, Vrije Universiteit Brussel, B-1090, Brussels, Belgium.
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25
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Oinonen T, Ronis M, Wigell T, Tohmo K, Badger T, Lindros KO. Growth hormone-regulated periportal expression of CYP2C7 in rat liver. Biochem Pharmacol 2000; 59:583-9. [PMID: 10660124 DOI: 10.1016/s0006-2952(99)00344-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Most drug- and steroid-metabolizing cytochrome P450 (CYP) enzymes are expressed in the mammalian liver in a characteristic zonated pattern, with high expression in the downstream perivenous (centrilobular) region. Here, we report that CYP2C7, a member of the rat CYP2 family, is expressed preferentially in the opposite, periportal region. CYP2C7 mRNA, as detected by reverse transcription-polymerase chain reaction, was detected almost exclusively in cell lysates obtained from the periportal region, indicating a very steep acinar gradient. The amount of immunoreactive CYP2C7 protein in periportal cell lysates was also higher than in samples from the perivenous region. This gradient was reversed by hypophysectomy, which markedly and selectively reduced the periportal CYP2C7 protein content. Subsequent growth hormone infusion by osmotic minipumps restored the zonation by selectively increasing the amount of periportal CYP2C7 protein. Although hypophysectomy suppressed CYP2C7 mRNA and growth hormone counteracted it, regulation at this level did not appear to occur in a zone-specific fashion. This indicates that growth hormone-mediated zonal regulation of CYP2C7 protein has additional translational or posttranslational components. Ethanol treatment, which has been shown to affect growth hormone levels, significantly induced CYP2C7 mRNA, but not zone specifically. Our results demonstrate that growth hormone up-regulates the CYP2C7 gene by enhancing the expression of the protein specifically in the periportal liver region. Growth hormone may up-regulate other periportally expressed liver genes in a similar fashion.
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Affiliation(s)
- T Oinonen
- Alcohol Research Center, National Public Health Institute, Helsinki, Finland
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26
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DiRusso CC, Black PN, Weimar JD. Molecular inroads into the regulation and metabolism of fatty acids, lessons from bacteria. Prog Lipid Res 1999; 38:129-97. [PMID: 10396600 DOI: 10.1016/s0163-7827(98)00022-8] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- C C DiRusso
- Department of Biochemistry and Molecular Biology, Albany Medical College, New York, USA.
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27
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Gupta S, Rajvanshi P, Sokhi RP, Vaidya S, Irani AN, Gorla GR. Position-specific gene expression in the liver lobule is directed by the microenvironment and not by the previous cell differentiation state. J Biol Chem 1999; 274:2157-65. [PMID: 9890978 DOI: 10.1074/jbc.274.4.2157] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mechanisms directing position-specific liver gene regulation are incompletely understood. To establish whether this aspect of hepatic gene expression is an inveterate phenomenon, we used transplanted hepatocytes as reporters in dipeptidyl peptidase IV-deficient F344 rats. After integration in liver parenchyma, the position of transplanted cells was shifted from periportal to perivenous areas by targeted hepatic ablations with carbon tetrachloride. In controls, transplanted cells showed greater glucose-6-phosphatase and lesser glycogen content in periportal areas. This pattern was reversed when transplanted cells shifted from periportal to perivenous areas. Transplanted hepatocytes in perivenous areas exhibited inducible cytochrome P450 activity, which was deficient in periportal hepatocytes. Moreover, cytochrome P450 activity was rapidly extinguished in activated hepatocytes when these cells were transplanted into the nonpermissive liver of suckling rat pups. In cells isolated from the normal F344 rat liver, cytochrome P450 inducibility was originally greater in perivenous hepatocytes; however, periportal cells rapidly acquired this facility in culture conditions. These findings indicate that the liver microenvironment exerts supremacy over prior differentiation state of cells in directing position-specific gene expression. Therefore, persistence of specialized hepatocellular function will require interactions with regulatory signals and substrate availability, which bears upon further analysis of liver gene regulation, including in progenitor and/or stem cells.
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Affiliation(s)
- S Gupta
- Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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28
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Oinonen T, Koivisto T, Lindros KO. No significant expression of CYP2E1 in rat liver stellate cells. Biochem Pharmacol 1998; 56:1075-8. [PMID: 9776321 DOI: 10.1016/s0006-2952(98)00062-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The putative role of the ethanol-inducible cytochrome P450(CYP)2E1 in stimulating collagen synthesis by rat liver stellate cells was studied. Analysis of carefully isolated stellate cells revealed that their content of immunoreactive CYP2E1 protein and of CYP2E1 mRNA, as determined by reverse transcription, polymerase chain reaction (RT-PCR), was very low, i.e. only 0-4% of that in hepatocytes. We conclude that it is improbable that such low expression of CYP2E1 in stellate cells would have functional importance.
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Affiliation(s)
- T Oinonen
- Alcohol Research Center, National Public Health Institute, Helsinki, Finland
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29
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Abstract
The CYP genes encode enzymes of the cytochrome P-450 superfamily. Cytochrome P-450 (CYP) enzymes are expressed mainly in the liver and are active in mono-oxygenation and hydroxylation of various xenobiotics, including drugs and alcohols, as well as that of endogenous compounds such as steroids, bile acids, prostaglandins, leukotrienes and biogenic amines. In the liver the CYP enzymes are constitutively expressed and commonly also induced by chemicals in a characteristic zonated pattern with high expression prevailing in the downstream perivenous region. In the present review we summarize recent studies, mainly based on rat liver, on the factors regulating this position-dependent expression and induction. Pituitary-dependent signals mediated by growth hormone and thyroid hormone seem to selectively down-regulate the upstream periportal expression of certain CYP forms. It is at present unknown to what extent other hormones that also affect total hepatic CYP activities, i.e. insulin, glucagon, glucocorticoids and gonadal hormones, act zone-specifically. The expression and induction of CYP enzymes in the perivenous region probably have important toxicological implications, since many CYP-activated chemicals cause cell injury primarily in this region of the liver.
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Affiliation(s)
- T Oinonen
- National Public Health Institute, Alcohol Research Center, PB 719, 00101 Helsinki, Finland
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