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Carter LE, Bugiel S, Nunnikhoven A, Verster AJ, Petronella N, Gill S, Curran IHA. Comparative genomic analysis of Fischer F344 rat livers exposed for 90 days to 3-methylfuran or its parental compound furan. Food Chem Toxicol 2024; 184:114426. [PMID: 38160780 DOI: 10.1016/j.fct.2023.114426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/22/2023] [Accepted: 12/23/2023] [Indexed: 01/03/2024]
Abstract
Furan is a naturally forming compound found in heat-processed foods such as coffee, canned meats, and jarred baby food. It is concurrently found with analogues including 2-methylfuran (2-MF) and 3-methylfuran (3-MF), and toxicity studies demonstrate all are potent liver toxins. Toxicity studies found 3-MF is more toxic than either furan, or 2-MF. The present analysis assesses the transcriptional response in liver samples taken from male Fischer (F344) rats exposed to furan or 3-MF from 0 to 2.0 and 0-1.0 mg/kg bw/day, respectively, for 90 days. Transcriptional analyses found decreased liver function and fatty acid metabolism are common responses to both furan and 3-MF exposure. Furan liver injury promotes a ductular reaction through Hippo and TGFB signalling, which combined with increased immune response results in ameliorating perturbed bile acid homeostasis in treated rats. Failure to activate these pathways in 3-MF exposed rats and decreased p53 activity leads to cholestasis, and increased toxicity. Finally, BMD analysis indicate many of the most sensitive pathways affected by furan and 3-MF exposure relate to metabolism - malate dehydrogenase and glucose metabolism with BMDLs of 0.03 and 0.01 mg/kg bw/day for furan and 3-MF exposure, respectively, which agrees with BMDLs previously reported for apical and microarray data.
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Affiliation(s)
- L E Carter
- Bureau of Chemical Safety, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, K1A 0K9, Canada.
| | - S Bugiel
- Bureau of Chemical Safety, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, K1A 0K9, Canada
| | - A Nunnikhoven
- Bureau of Chemical Safety, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, K1A 0K9, Canada
| | - A J Verster
- Bureau of Food Surveillance and Science Integration, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, K1A 0K9, Canada
| | - N Petronella
- Bureau of Food Surveillance and Science Integration, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, K1A 0K9, Canada
| | - S Gill
- Bureau of Chemical Safety, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, K1A 0K9, Canada
| | - I H A Curran
- Bureau of Chemical Safety, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, K1A 0K9, Canada
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Hang L, Wang E, Feng Y, Zhou Y, Meng Y, Jiang F, Yuan J. Metagenomics and metabolomics analysis to investigate the effect of Shugan decoction on intestinal microbiota in irritable bowel syndrome rats. Front Microbiol 2022; 13:1024822. [PMID: 36478867 PMCID: PMC9719954 DOI: 10.3389/fmicb.2022.1024822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 11/07/2022] [Indexed: 08/30/2023] Open
Abstract
BACKGROUND The effect of Shugan Decoction (SGD) on intestinal motility and visceral hypersensitivity in Water avoid stress (WAS)-induced diarrhea predominant irritable bowel syndrome (IBS-D) model rats has been confirmed. However, the mechanisms of its action involved in the treatment of IBS-D need to be further studied. Intestinal microbiota plays an important role in maintaining intestinal homeostasis and normal physiological function. Changes in the intestinal microbiota and its metabolites are thought to participate in the pathophysiological process of IBS. AIM This study aimed to analyze the influence of SGD on intestinal microbiota and fecal metabolites in IBS-D rats by multiple omics techniques, including metagenomic sequencing and metabolomics. METHODS We measured the intestinal motility and visceral sensitivity of three groups of rats by fecal pellets output and colorectal distension (CRD) experiment. In addition, metagenome sequencing analysis was performed to explore the changes in the number and types of intestinal microbiota in IBS-D model rats after SGD treatment. Finally, we also used untargeted metabolomic sequencing to screen the metabolites and metabolic pathways closely related to the therapeutic effect of SGD. RESULTS We found that compared with the rats in the control group, the fecal pellets output of the rats in the WAS group increased and the visceral sensitivity threshold was decreased (P < 0.05). Compared with the rats in the WAS group, the fecal pellets output of the SGD group was significantly decreased, and the visceral sensitivity threshold increased (P < 0.05). Besides, compared with the rats in the WAS group, the relative abundance of Bacteroidetes increased in SGD group, while that of Firmicutes decreased at the phylum level, and at the species level, the relative abundance of Bacteroides sp. CAG:714, Lactobacillus reuteri and Bacteroides Barnesiae in SGD group increased, but that of bacterium D42-87 decreased. In addition, compared with the WAS group, several metabolic pathways were significantly changed in SGD group, including Taurine and hypotaurine metabolism, Purine metabolism, Sulfur metabolism, ABC transporters, Arginine and proline metabolism and Bile secretion. CONCLUSION SGD can regulate specific intestinal microbiota and some metabolic pathways, which may explain its effect of alleviating visceral hypersensitivity and abnormal intestinal motility in WAS-induced IBS-D rats.
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Affiliation(s)
| | | | | | | | | | | | - Jianye Yuan
- Institute of Digestive Diseases, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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Bardeck N, Paluschinski M, Castoldi M, Kordes C, Görg B, Stindt J, Luedde T, Dahl SV, Häussinger D, Schöler D. Swelling-induced upregulation of miR-141-3p inhibits hepatocyte proliferation. JHEP REPORTS : INNOVATION IN HEPATOLOGY 2022; 4:100440. [PMID: 35287291 PMCID: PMC8917307 DOI: 10.1016/j.jhepr.2022.100440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 12/19/2021] [Accepted: 12/23/2021] [Indexed: 11/29/2022]
Abstract
Background & Aims Methods Results Conclusions Lay summary Gene expression changes in hypoosmotic perfused rat liver. Hypoosmolarity upregulates miR-141-3p in rat perfused liver and primary hepatocytes. Src-/Erk-/p38-MAPK-inhibition prevents miR-141-3p upregulation by hypoosmolarity. PHx and hepatocyte stretch transiently upregulate miR-141-3p, which downregulates Cdk8 mRNA. Overexpression of miR-141-3p inhibits Huh7 cell proliferation.
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Affiliation(s)
- Nils Bardeck
- Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Düsseldorf, Germany
| | - Martha Paluschinski
- Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Düsseldorf, Germany
| | - Mirco Castoldi
- Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Düsseldorf, Germany
| | - Claus Kordes
- Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Düsseldorf, Germany
| | - Boris Görg
- Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Düsseldorf, Germany
| | - Jan Stindt
- Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Düsseldorf, Germany
| | - Tom Luedde
- Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Düsseldorf, Germany
| | - Stephan vom Dahl
- Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Düsseldorf, Germany
| | - Dieter Häussinger
- Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Düsseldorf, Germany
| | - David Schöler
- Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Düsseldorf, Germany
- Corresponding author. Address: Department of Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Hospital, Moorenstrasse 5, 40225 Düsseldorf, Germany. Tel.: +49-(0)211-81-16330; Fax: +49-(0)211-81-18752..
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Beuers U. EASL recognition award recipient 2021: Prof. Dieter Häussinger. J Hepatol 2021; 75:7-9. [PMID: 34144734 DOI: 10.1016/j.jhep.2021.04.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 04/26/2021] [Indexed: 12/04/2022]
Affiliation(s)
- Ulrich Beuers
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands.
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Bonus M, Häussinger D, Gohlke H. Liver cell hydration and integrin signaling. Biol Chem 2021; 402:1033-1045. [PMID: 33915604 DOI: 10.1515/hsz-2021-0193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 04/12/2021] [Indexed: 12/21/2022]
Abstract
Liver cell hydration (cell volume) is dynamic and can change within minutes under the influence of hormones, nutrients, and oxidative stress. Such volume changes were identified as a novel and important modulator of cell function. It provides an early example for the interaction between a physical parameter (cell volume) on the one hand and metabolism, transport, and gene expression on the other. Such events involve mechanotransduction (osmosensing) which triggers signaling cascades towards liver function (osmosignaling). This article reviews our own work on this topic with emphasis on the role of β1 integrins as (osmo-)mechanosensors in the liver, but also on their role in bile acid signaling.
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Affiliation(s)
- Michele Bonus
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology, and Infectious Diseases, Heinrich Heine University Düsseldorf, Moorenstr. 5, D-40225 Düsseldorf, Germany
| | - Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), Wilhelm-Johnen-Str., D-52428 Jülich, Germany
- Institute of Biological Information Processing (IBI-7: Structural Biochemistry), and Institute of Bio- and Geosciences (IBG-4: Bioinformatics), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Str., D-52428 Jülich, Germany
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Paluschinski M, Castoldi M, Schöler D, Bardeck N, Oenarto J, Görg B, Häussinger D. Tauroursodeoxycholate protects from glycochenodeoxycholate-induced gene expression changes in perfused rat liver. Biol Chem 2020; 400:1551-1565. [PMID: 31152635 DOI: 10.1515/hsz-2019-0204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 05/16/2019] [Indexed: 02/07/2023]
Abstract
Tauroursodeoxycholate (TUDC) is well known to protect against glycochenodeoxycholate (GCDC)-induced apoptosis in rat hepatocytes. In the present study, we analyzed whether TUDC also exerts protective effects by modulating GCDC-induced gene expression changes. For this, gene array-based transcriptome analysis and quantitative polymerase chain reaction (qPCR) were performed on RNA isolated from rat livers perfused with GCDC, TUDC or a combination of both (each 20 μm for 2 h). GCDC led to a significant increase of lactate dehydrogenase (LDH) into the effluent perfusate, which was prevented by TUDC. GCDC, TUDC and co-perfusion induced distinct gene expression changes. While GCDC upregulated the expression of several pro-inflammatory genes, co-perfusion with TUDC increased the expression of pro-proliferative and anti-apoptotic p53 target genes. In line with this, levels of serine20-phosphorylated p53 and of its target gene p21 were elevated by GCDC in a TUDC-sensitive way. GCDC upregulated the oxidative stress surrogate marker 8OH(d)G and the pro-apoptotic microRNAs miR-15b/16 and these effects were prevented by TUDC. The upregulation of miR-15b and miR-16 in GCDC-perfused livers was accompanied by a downregulation of several potential miR-15b and miR-16 target genes. The present study identified changes in the transcriptome of the rat liver which suggest, that TUDC is hepatoprotective by counteracting GCDC-induced gene expression changes.
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Affiliation(s)
- Martha Paluschinski
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Mirco Castoldi
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - David Schöler
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Nils Bardeck
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Jessica Oenarto
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Boris Görg
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
| | - Dieter Häussinger
- Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany
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Evidence for functional selectivity in TUDC- and norUDCA-induced signal transduction via α 5β 1 integrin towards choleresis. Sci Rep 2020; 10:5795. [PMID: 32242141 PMCID: PMC7118123 DOI: 10.1038/s41598-020-62326-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 03/02/2020] [Indexed: 01/06/2023] Open
Abstract
Functional selectivity is the ligand-specific activation of certain signal transduction pathways at a receptor and has been described for G protein-coupled receptors. However, it has not yet been described for ligands interacting with integrins without αI domain. Here, we show by molecular dynamics simulations that four side chain-modified derivatives of tauroursodeoxycholic acid (TUDC), an agonist of α5β1 integrin, differentially shift the conformational equilibrium of α5β1 integrin towards the active state, in line with the extent of β1 integrin activation from immunostaining. Unlike TUDC, 24-nor-ursodeoxycholic acid (norUDCA)-induced β1 integrin activation triggered only transient activation of extracellular signal-regulated kinases and p38 mitogen-activated protein kinase and, consequently, only transient insertion of the bile acid transporter Bsep into the canalicular membrane, and did not involve activation of epidermal growth factor receptor. These results provide evidence that TUDC and norUDCA exert a functional selectivity at α5β1 integrin and may provide a rationale for differential therapeutic use of UDCA and norUDCA.
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8
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Hohenester S, Kanitz V, Kremer AE, Paulusma CC, Wimmer R, Kuehn H, Denk G, Horst D, Oude Elferink R, Beuers U. Glycochenodeoxycholate Promotes Liver Fibrosis in Mice with Hepatocellular Cholestasis. Cells 2020; 9:cells9020281. [PMID: 31979271 PMCID: PMC7072501 DOI: 10.3390/cells9020281] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/15/2020] [Accepted: 01/19/2020] [Indexed: 02/06/2023] Open
Abstract
Hydrophobic bile salts are considered to promote liver fibrosis in cholestasis. However, evidence for this widely accepted hypothesis remains scarce. In established animal models of cholestasis, e.g., by Mdr2 knockout, cholestasis and fibrosis are both secondary to biliary damage. Therefore, to test the specific contribution of accumulating bile salts to liver fibrosis in cholestatic disease, we applied the unique model of inducible hepatocellular cholestasis in cholate-fed Atp8b1G308V/G308V mice. Glycochenodeoxycholate (GCDCA) was supplemented to humanize the murine bile salt pool, as confirmed by HPLC. Biomarkers of cholestasis and liver fibrosis were quantified. Hepatic stellate cells (HSC) isolated from wild-type mice were stimulated with bile salts. Proliferation, cell accumulation, and collagen deposition of HSC were determined. In cholestatic Atp8b1G308V/G308V mice, increased hepatic expression of αSMA and collagen1a mRNA and excess hepatic collagen deposition indicated development of liver fibrosis only upon GCDCA supplementation. In vitro, numbers of myofibroblasts and deposition of collagen were increased after incubation with hydrophobic but not hydrophilic bile salts, and associated with EGFR and MEK1/2 activation. We concluded that chronic hepatocellular cholestasis alone, independently of biliary damage, induces liver fibrosis in mice in presence of the human bile salt GCDCA. Bile salts may have direct pro-fibrotic effects on HSC, putatively involving EGFR and MEK1/2 signaling.
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Affiliation(s)
- Simon Hohenester
- Department of Medicine II, University Hospital, LMU Munich, 81377 Munich, Germany; (R.W.); (G.D.)
- Correspondence:
| | - Veronika Kanitz
- Institute of Pathology, Faculty of Medicine, LMU Munich, 80337 Munich, Germany;
| | - Andreas E. Kremer
- Department of Medicine I, Friedrich-Alexander-University Erlangen-Nürnberg, 91054 Erlangen, Germany; (A.E.K.); (H.K.)
| | - Coen C. Paulusma
- Tytgat Institute for Liver and Intestinal Research, Department of Gastroenterology and Hepatology, Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, University of Amsterdam, 1018 TV Amsterdam, The Netherlands; (C.C.P.); (R.O.E.); (U.B.)
| | - Ralf Wimmer
- Department of Medicine II, University Hospital, LMU Munich, 81377 Munich, Germany; (R.W.); (G.D.)
| | - Helen Kuehn
- Department of Medicine I, Friedrich-Alexander-University Erlangen-Nürnberg, 91054 Erlangen, Germany; (A.E.K.); (H.K.)
| | - Gerald Denk
- Department of Medicine II, University Hospital, LMU Munich, 81377 Munich, Germany; (R.W.); (G.D.)
| | - David Horst
- Department of Pathology, Charité—Universitätsmedizin, 10117 Berlin, Germany;
| | - Ronald Oude Elferink
- Tytgat Institute for Liver and Intestinal Research, Department of Gastroenterology and Hepatology, Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, University of Amsterdam, 1018 TV Amsterdam, The Netherlands; (C.C.P.); (R.O.E.); (U.B.)
| | - Ulrich Beuers
- Tytgat Institute for Liver and Intestinal Research, Department of Gastroenterology and Hepatology, Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, University of Amsterdam, 1018 TV Amsterdam, The Netherlands; (C.C.P.); (R.O.E.); (U.B.)
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Kusaczuk M. Tauroursodeoxycholate-Bile Acid with Chaperoning Activity: Molecular and Cellular Effects and Therapeutic Perspectives. Cells 2019; 8:E1471. [PMID: 31757001 PMCID: PMC6952947 DOI: 10.3390/cells8121471] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/15/2019] [Accepted: 11/19/2019] [Indexed: 12/11/2022] Open
Abstract
Tauroursodeoxycholic acid (TUDCA) is a naturally occurring hydrophilic bile acid that has been used for centuries in Chinese medicine. Chemically, TUDCA is a taurine conjugate of ursodeoxycholic acid (UDCA), which in contemporary pharmacology is approved by Food and Drug Administration (FDA) for treatment of primary biliary cholangitis. Interestingly, numerous recent studies demonstrate that mechanisms of TUDCA functioning extend beyond hepatobiliary disorders. Thus, TUDCA has been demonstrated to display potential therapeutic benefits in various models of many diseases such as diabetes, obesity, and neurodegenerative diseases, mostly due to its cytoprotective effect. The mechanisms underlying this cytoprotective activity have been mainly attributed to alleviation of endoplasmic reticulum (ER) stress and stabilization of the unfolded protein response (UPR), which contributed to naming TUDCA as a chemical chaperone. Apart from that, TUDCA has also been found to reduce oxidative stress, suppress apoptosis, and decrease inflammation in many in-vitro and in-vivo models of various diseases. The latest research suggests that TUDCA can also play a role as an epigenetic modulator and act as therapeutic agent in certain types of cancer. Nevertheless, despite the massive amount of evidence demonstrating positive effects of TUDCA in pre-clinical studies, there are certain limitations restraining its wide use in patients. Here, molecular and cellular modes of action of TUDCA are described and therapeutic opportunities and limitations of this bile acid are discussed.
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Affiliation(s)
- Magdalena Kusaczuk
- Department of Pharmaceutical Biochemistry, Medical University of Białystok, Mickiewicza 2A, 15-222 Białystok, Poland
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Roma MG, Barosso IR, Miszczuk GS, Crocenzi FA, Pozzi EJS. Dynamic Localization of Hepatocellular Transporters: Role in Biliary Excretion and Impairment in Cholestasis. Curr Med Chem 2019; 26:1113-1154. [DOI: 10.2174/0929867325666171205153204] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 09/06/2017] [Accepted: 09/07/2017] [Indexed: 12/25/2022]
Abstract
Bile flow generation is driven by the vectorial transfer of osmotically active compounds from sinusoidal blood into a confined space, the bile canaliculus. Hence, localization of hepatocellular transporters relevant to bile formation is crucial for bile secretion. Hepatocellular transporters are localized either in the plasma membrane or in recycling endosomes, from where they can be relocated to the plasma membrane on demand, or endocytosed when the demand decreases. The balance between endocytic internalization/ exocytic targeting to/from this recycling compartment is therefore the main determinant of the hepatic capability to generate bile, and to dispose endo- and xenobiotics. Furthermore, the exacerbated endocytic internalization is a common pathomechanisms in both experimental and human cholestasis; this results in bile secretory failure and, eventually, posttranslational transporter downregulation by increased degradation. This review summarizes the proposed structural mechanisms accounting for this pathological condition (e.g., alteration of function, localization or expression of F-actin or F-actin/transporter cross-linking proteins, and switch to membrane microdomains where they can be readily endocytosed), and the mediators implicated (e.g., triggering of “cholestatic” signaling transduction pathways). Lastly, we discussed the efficacy to counteract the cholestatic failure induced by transporter internalization of a number of therapeutic experimental approaches based upon the use of compounds that trigger exocytic targetting of canalicular transporters (e.g., cAMP, tauroursodeoxycholate). This therapeutics may complement treatments aimed to transcriptionally improve transporter expression, by affording proper localization and membrane stability to the de novo synthesized transporters.
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Affiliation(s)
- Marcelo G. Roma
- Instituto de Fisiologia Experimental (IFISE) - Facultad de Ciencias Bioquimicas y Farmaceuticas (CONICET - U.N.R.), S2002LRL, Rosario, Argentina
| | - Ismael R. Barosso
- Instituto de Fisiologia Experimental (IFISE) - Facultad de Ciencias Bioquimicas y Farmaceuticas (CONICET - U.N.R.), S2002LRL, Rosario, Argentina
| | - Gisel S. Miszczuk
- Instituto de Fisiologia Experimental (IFISE) - Facultad de Ciencias Bioquimicas y Farmaceuticas (CONICET - U.N.R.), S2002LRL, Rosario, Argentina
| | - Fernando A. Crocenzi
- Instituto de Fisiologia Experimental (IFISE) - Facultad de Ciencias Bioquimicas y Farmaceuticas (CONICET - U.N.R.), S2002LRL, Rosario, Argentina
| | - Enrique J. Sánchez Pozzi
- Instituto de Fisiologia Experimental (IFISE) - Facultad de Ciencias Bioquimicas y Farmaceuticas (CONICET - U.N.R.), S2002LRL, Rosario, Argentina
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Bivalent Ligand UDCA-LPE Inhibits Pro-Fibrogenic Integrin Signalling by Inducing Lipid Raft-Mediated Internalization. Int J Mol Sci 2018; 19:ijms19103254. [PMID: 30347788 PMCID: PMC6214129 DOI: 10.3390/ijms19103254] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 10/08/2018] [Accepted: 10/10/2018] [Indexed: 01/07/2023] Open
Abstract
Ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE) is a synthetic bile acid-phospholipid conjugate with profound hepatoprotective and anti-fibrogenic functions in vitro and in vivo. Herein, we aimed to demonstrate the inhibitory effects of UDCA-LPE on pro-fibrogenic integrin signalling. UDCA-LPE treatment of human embryonic liver cell line CL48 and primary human hepatic stellate cells induced a non-classical internalization of integrin β1 resulting in dephosphorylation and inhibition of SRC and focal adhesion kinase (FAK). Signalling analyses suggested that UDCA-LPE may act as a heterobivalent ligand for integrins and lysophospholipid receptor1 (LPAR1) and co-immunoprecipitation demonstrated the bridging effect of UDCA-LPE on integrin β1 and LPAR1. The disruption of either the UDCA-moiety binding to integrins by RGD-containing peptide GRGDSP or the LPE-moiety binding to LPAR1 by LPAR1 antagonist Ki16425 reversed inhibitory functions of UDCA-LPE. The lack of inhibitory functions of UDCA-PE and UDCA-LPE derivatives (14:0 and 12:0, LPE-moiety containing shorter fatty acid chain) as well as the consistency of the translocation of UDCA-LPE and integrins, which co-fractionated with LPE but not UDCA, suggested that the observed UDCA-LPE-induced translocation of integrins was mediated by LPE endocytic transport pathway.
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Voiosu A, Wiese S, Voiosu T, Bendtsen F, Møller S. Bile acids and cardiovascular function in cirrhosis. Liver Int 2017; 37:1420-1430. [PMID: 28222247 DOI: 10.1111/liv.13394] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 02/12/2017] [Indexed: 02/13/2023]
Abstract
Cirrhotic cardiomyopathy and the hyperdynamic syndrome are clinically important complications of cirrhosis, but their exact pathogenesis is still partly unknown. Experimental models have proven the cardiotoxic effects of bile acids and recent studies of their varied receptor-mediated functions offer new insight into their involvement in cardiovascular dysfunction in cirrhosis. Bile acid receptors such as farnesoid X-activated receptor and TGR5 are currently under investigation as potential therapeutic targets in a variety of pathological conditions. These receptors have also recently been identified in cardiomyocytes, vascular endothelial cells and smooth muscle cells where they seem to play an important role in cellular metabolism. Chronic cholestasis leading to abnormal levels of circulating bile acids alters the normal signalling pathways and contributes to the development of profound cardiovascular disturbances. This review summarizes the evidence regarding the role of bile acids and their receptors in the generation of cardiovascular dysfunction in cirrhosis.
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Affiliation(s)
- Andrei Voiosu
- Department of Clinical Physiology and Nuclear Medicine, Center for Functional and Diagnostic Imaging and Research, Hvidovre Hospital, Hvidovre, Denmark.,Gastroenterology and Hepatology Department, Colentina Clinical Hospital, Bucharest, Romania.,"Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania
| | - Signe Wiese
- Department of Clinical Physiology and Nuclear Medicine, Center for Functional and Diagnostic Imaging and Research, Hvidovre Hospital, Hvidovre, Denmark.,Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Theodor Voiosu
- Gastroenterology and Hepatology Department, Colentina Clinical Hospital, Bucharest, Romania.,"Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania
| | - Flemming Bendtsen
- Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,Gastro Unit, Medical Division, Hvidovre Hospital, Hvidovre, Denmark
| | - Søren Møller
- Department of Clinical Physiology and Nuclear Medicine, Center for Functional and Diagnostic Imaging and Research, Hvidovre Hospital, Hvidovre, Denmark.,Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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13
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Abstract
PURPOSE OF REVIEW The only currently approved treatment for primary sclerosing cholangitis (PSC) is liver transplantation, with a median time to transplant of 12-18 years after diagnosis. There are a number of emerging drugs that have the potential to meet this critically unmet need that will be summarized and discussed herein. RECENT FINDINGS Although the cause of PSC is unknown, there are a number of novel therapeutics under development. These drugs target presumed pathogenic mechanisms largely extrapolated from ex-vivo and in-vivo preclinical models, as well as translational observations. SUMMARY Future therapeutic strategies for PSC may include a multitude of complex pathogenic mechanisms encompassing pathways of immunomodulation, the microbiome and inflammation-related fibrosis.
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Affiliation(s)
- Angela C Cheung
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
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14
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Mitogen-activated protein kinases are involved in hepatocanalicular dysfunction and cholestasis induced by oxidative stress. Arch Toxicol 2016; 91:2391-2403. [PMID: 27913845 DOI: 10.1007/s00204-016-1898-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 11/24/2016] [Indexed: 12/22/2022]
Abstract
In previous studies, we showed that the pro-oxidant model agent tert-butyl hydroperoxide (tBuOOH) induces alterations in hepatocanalicular secretory function by activating Ca2+-dependent protein kinase C isoforms (cPKC), via F-actin disorganization followed by endocytic internalization of canalicular transporters relevant to bile formation (Mrp2, Bsep). Since mitogen-activated protein kinases (MAPKs) may be downstream effectors of cPKC, we investigated here the involvement of the MAPKs of the ERK1/2, JNK1/2, and p38MAPK types in these deleterious effects. tBuOOH (100 µM, 15 min) increased the proportion of the active, phosphorylated forms of ERK1/2, JNK1/2, and p38MAPK, and panspecific PKC inhibition with bisindolylmaleimide-1 (100 nM) or selective cPKC inhibition with Gö6976 (1 μM) prevented the latter two events. In isolated rat hepatocyte couplets, tBuOOH (100 µM, 15 min) decreased the canalicular vacuolar accumulation of the fluorescent Bsep and Mrp2 substrates, cholylglycylamido fluorescein, and glutathione-methylfluorescein, respectively, and selective inhibitors of ERK1/2 (PD098059), JNK1/2 (SP600125), and p38MAPK (SB203580) partially prevented these alterations. In in situ perfused rat livers, these three MAPK inhibitors prevented tBuOOH (75 µM)-induced impairment of bile flow and the decrease in the biliary output of the Bsep and Mrp2 substrates, taurocholate, and dinitrophenyl-S-glutathione, respectively. The changes in Bsep/Mrp2 and F-actin localization induced by tBuOOH, as assessed by (immuno)fluorescence staining followed by analysis of confocal images, were prevented total or partially by the MAPK inhibitors. We concluded that MAPKs of the ERK1/2, JNK1/2, and p38MAPK types are all involved in cholestasis induced by oxidative stress, by promoting F-actin rearrangement and further endocytic internalization of canalicular transporters critical for bile formation.
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15
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Pharmacology of bile acid receptors: Evolution of bile acids from simple detergents to complex signaling molecules. Pharmacol Res 2015; 104:9-21. [PMID: 26706784 DOI: 10.1016/j.phrs.2015.12.007] [Citation(s) in RCA: 153] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 12/03/2015] [Indexed: 12/17/2022]
Abstract
For many years, bile acids were thought to only function as detergents which solubilize fats and facilitate the uptake of fat-soluble vitamins in the intestine. Many early observations; however, demonstrated that bile acids regulate more complex processes, such as bile acids synthesis and immune cell function through activation of signal transduction pathways. These studies were the first to suggest that receptors may exist for bile acids. Ultimately, seminal studies by many investigators led to the discovery of several bile acid-activated receptors including the farnesoid X receptor, the vitamin D receptor, the pregnane X receptor, TGR5, α5 β1 integrin, and sphingosine-1-phosphate receptor 2. Several of these receptors are expressed outside of the gastrointestinal system, indicating that bile acids may have diverse functions throughout the body. Characterization of the functions of these receptors over the last two decades has identified many important roles for these receptors in regulation of bile acid synthesis, transport, and detoxification; regulation of glucose utilization; regulation of fatty acid synthesis and oxidation; regulation of immune cell function; regulation of energy expenditure; and regulation of neural processes such as gastric motility. Through these many functions, bile acids regulate many aspects of digestion ranging from uptake of essential vitamins to proper utilization of nutrients. Accordingly, within a short time period, bile acids moved beyond simple detergents and into the realm of complex signaling molecules. Because of the important processes that bile acids regulate through activation of receptors, drugs that target these receptors are under development for the treatment of several diseases, including cholestatic liver disease and metabolic syndrome. In this review, we will describe the various bile acid receptors, the signal transduction pathways activated by these receptors, and briefly discuss the physiological processes that these receptors regulate.
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16
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Sommerfeld A, Mayer PGK, Cantore M, Häussinger D. Regulation of plasma membrane localization of the Na+-taurocholate cotransporting polypeptide (Ntcp) by hyperosmolarity and tauroursodeoxycholate. J Biol Chem 2015; 290:24237-54. [PMID: 26306036 DOI: 10.1074/jbc.m115.666883] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Indexed: 01/05/2023] Open
Abstract
In perfused rat liver, hepatocyte shrinkage induces a Fyn-dependent retrieval of the bile salt export pump (Bsep) and multidrug resistance-associated protein 2 (Mrp2) from the canalicular membrane (Cantore, M., Reinehr, R., Sommerfeld, A., Becker, M., and Häussinger, D. (2011) J. Biol. Chem. 286, 45014-45029) leading to cholestasis. However little is known about the effects of hyperosmolarity on short term regulation of the Na(+)-taurocholate cotransporting polypeptide (Ntcp), the major bile salt uptake system at the sinusoidal membrane of hepatocytes. The aim of this study was to analyze hyperosmotic Ntcp regulation and the underlying signaling events. Hyperosmolarity induced a significant retrieval of Ntcp from the basolateral membrane, which was accompanied by an activating phosphorylation of the Src kinases Fyn and Yes but not of c-Src. Hyperosmotic internalization of Ntcp was sensitive to SU6656 and PP-2, suggesting that Fyn mediates Ntcp retrieval from the basolateral membrane. Hyperosmotic internalization of Ntcp was also found in livers from wild-type mice but not in p47(phox) knock-out mice. Tauroursodeoxycholate (TUDC) and cAMP reversed hyperosmolarity-induced Fyn activation and triggered re-insertion of the hyperosmotically retrieved Ntcp into the membrane. This was associated with dephosphorylation of the Ntcp on serine residues. Insertion of Ntcp by TUDC was sensitive to the integrin inhibitory hexapeptide GRGDSP and inhibition of protein kinase A. TUDC also reversed the hyperosmolarity-induced retrieval of bile salt export pump from the canalicular membrane. These findings suggest a coordinated and oxidative stress- and Fyn-dependent retrieval of sinusoidal and canalicular bile salt transport systems from the corresponding membranes. Ntcp insertion was also identified as a novel target of β1-integrin-dependent TUDC action, which is frequently used in the treatment of cholestatic liver disease.
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Affiliation(s)
- Annika Sommerfeld
- From the Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Patrick G K Mayer
- From the Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Miriam Cantore
- From the Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
| | - Dieter Häussinger
- From the Clinic for Gastroenterology, Hepatology and Infectious Diseases, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany
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17
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Beuers U, Trauner M, Jansen P, Poupon R. New paradigms in the treatment of hepatic cholestasis: from UDCA to FXR, PXR and beyond. J Hepatol 2015; 62:S25-37. [PMID: 25920087 DOI: 10.1016/j.jhep.2015.02.023] [Citation(s) in RCA: 333] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 02/16/2015] [Accepted: 02/16/2015] [Indexed: 02/08/2023]
Abstract
Cholestasis is an impairment of bile formation/flow at the level of the hepatocyte and/or cholangiocyte. The first, and for the moment, most established medical treatment is the natural bile acid (BA) ursodeoxycholic acid (UDCA). This secretagogue improves, e.g. in intrahepatic cholestasis of pregnancy or early stage primary biliary cirrhosis, impaired hepatocellular and cholangiocellular bile formation mainly by complex post-transcriptional mechanisms. The limited efficacy of UDCA in various cholestatic conditions urges for development of novel therapeutic approaches. These include nuclear and membrane receptor agonists and BA derivatives. The nuclear receptors farnesoid X receptor (FXR), retinoid X receptor (RXR), peroxisome proliferator-activated receptor α (PPARα), and pregnane X receptor (PXR) are transcriptional modifiers of bile formation and at present are under investigation as promising targets for therapeutic interventions in cholestatic disorders. The membrane receptors fibroblast growth factor receptor 4 (FGFR4) and apical sodium BA transporter (ASBT) deserve attention as additional therapeutic targets, as does the potential therapeutic agent norUDCA, a 23-C homologue of UDCA. Here, we provide an overview on established and future promising therapeutic agents and their potential molecular mechanisms and sites of action in cholestatic diseases.
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Affiliation(s)
- Ulrich Beuers
- Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Academic Medical Centre University of Amsterdam, Amsterdam, The Netherlands.
| | - Michael Trauner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Austria
| | - Peter Jansen
- Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Academic Medical Centre University of Amsterdam, Amsterdam, The Netherlands
| | - Raoul Poupon
- UPMC Université Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, AP-HP, Hôpital Saint-Antoine, Service d'Hépatologie, F-75012 Paris, France
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18
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Chen K, Geng S, Yuan R, Diao N, Upchurch Z, Li L. Super-low dose endotoxin pre-conditioning exacerbates sepsis mortality. EBioMedicine 2015; 2:324-333. [PMID: 26029736 PMCID: PMC4445878 DOI: 10.1016/j.ebiom.2015.03.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Sepsis mortality varies dramatically in individuals of variable immune conditions, with poorly defined mechanisms. This phenomenon complements the hypothesis that innate immunity may adopt rudimentary memory, as demonstrated in vitro with endotoxin priming and tolerance in cultured monocytes. However, previous in vivo studies only examined the protective effect of endotoxin tolerance in the context of sepsis. In sharp contrast, we report herein that pre-conditioning with super-low or low dose endotoxin lipopolysaccharide (LPS) cause strikingly opposite survival outcomes. Mice pre-conditioned with super-low dose LPS experienced severe tissue damage, inflammation, increased bacterial load in circulation, and elevated mortality when they were subjected to cecal-ligation and puncture (CLP). This is in contrast to the well-reported protective phenomenon with CLP mice pre-conditioned with low dose LPS. Mechanistically, we demonstrated that super-low and low dose LPS differentially modulate the formation of neutrophil extracellular trap (NET) in neutrophils. Instead of increased ERK activation and NET formation in neutrophils pre-conditioned with low dose LPS, we observed significantly reduced ERK activation and compromised NET generation in neutrophils pre-conditioned with super-low dose LPS. Collectively, our findings reveal a mechanism potentially responsible for the dynamic programming of innate immunity in vivo as it relates to sepsis risks. Super-low dose endotoxin pre-conditioning exacerbates, while higher dose endotoxin alleviates sepsis mortality. Super-low dose endotoxin reduces, while higher dose endotoxin facilitates neutrophil extracellular trap (NET) formation. Super-low dose endotoxin suppresses, while higher dose endotoxin induces ERK activation required for NET formation.
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Affiliation(s)
- Keqiang Chen
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
| | - Shuo Geng
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
| | - Ruoxi Yuan
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
| | - Na Diao
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
| | - Zachary Upchurch
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
| | - Liwu Li
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
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19
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Dyson JK, Hirschfield GM, Adams DH, Beuers U, Mann DA, Lindor KD, Jones DEJ. Novel therapeutic targets in primary biliary cirrhosis. Nat Rev Gastroenterol Hepatol 2015; 12:147-58. [PMID: 25645973 DOI: 10.1038/nrgastro.2015.12] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Primary biliary cirrhosis (PBC) is a chronic immune-mediated liver disease characterized by progressive cholestasis, biliary fibrosis and eventually cirrhosis. It results in characteristic symptoms with marked effects on life quality. The advent of large patient cohorts has challenged the view of PBC as a benign condition treated effectively by the single licensed therapy-ursodeoxycholic acid (UDCA). UDCA nonresponse or under-response has a major bearing on outcome, substantially increasing the likelihood that liver transplantation will be required or that patients will die of the disease. In patients with high-risk, treatment-unresponsive or highly symptomatic disease the need for new treatment approaches is clear. Evolution in our understanding of disease mechanisms is rapidly leading to the advent of new and re-purposed therapeutic agents targeting key processes. Notable opportunities are offered by targeting what could be considered as the 'upstream' immune response, 'midstream' biliary injury and 'downstream' fibrotic processes. Combination therapy targeting several pathways or the development of novel agents addressing multiple components of the disease pathway might be required. Ultimately, PBC therapeutics will require a stratified approach to be adopted in practice. This Review provides a current perspective on potential approaches to PBC treatment, and highlights the challenges faced in evaluating and implementing those treatments.
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Affiliation(s)
- Jessica K Dyson
- Institute of Cellular Medicine, 3rd Floor William Leech Building, Medical School, Framlington Place, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Gideon M Hirschfield
- Centre for Liver Research, NIHR Biomedical Research Unit, University of Birmingham, Wolfson Drive, Birmingham B15 2TT, UK
| | - David H Adams
- Centre for Liver Research, NIHR Biomedical Research Unit, University of Birmingham, Wolfson Drive, Birmingham B15 2TT, UK
| | - Ulrich Beuers
- Department of Gastroenterology &Hepatology, Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, G4-216, University of Amsterdam, PO Box 22600, NL-1100 DD, Amsterdam, Netherlands
| | - Derek A Mann
- Institute of Cellular Medicine, 3rd Floor William Leech Building, Medical School, Framlington Place, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Keith D Lindor
- College of Health Solutions, Arizona State University, 550 North 3rd Street, Phoenix, AZ 85004, USA
| | - David E J Jones
- Institute of Cellular Medicine, 3rd Floor William Leech Building, Medical School, Framlington Place, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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20
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Gani AR, Uppala JK, Ramaiah KVA. Tauroursodeoxycholic acid prevents stress induced aggregation of proteins in vitro and promotes PERK activation in HepG2 cells. Arch Biochem Biophys 2015; 568:8-15. [PMID: 25579883 DOI: 10.1016/j.abb.2014.12.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 12/27/2014] [Accepted: 12/30/2014] [Indexed: 12/15/2022]
Abstract
Tauroursodeoxycholic acid (TUDCA) a bile salt and chemical chaperone reduces stress-induced aggregation of proteins; activates PERK [PKR (RNA-dependent protein kinase)-like ER (endoplasmic reticulum) kinase] or EIF2AK3, one of the hall marks of ER stress induced unfolded protein response (UPR) in human hepatoblastoma HepG2 cells; prevents heat and dithiothreitol (DTT) induced aggregation of BSA (bovine serum albumin), and reduces ANS (1-anilino-naphthalene-8-sulfonate) bound BSA fluorescence in vitro. TUDCA inactivates heat treated, but not the native EcoR1 enzyme, and reduces heat-induced aggregation and activity of COX-1 (cyclooxygenase enzyme-1) in vitro. These findings suggest that TUDCA binds to the hydrophobic regions of proteins and prevents their subsequent aggregation. This may stabilize unfolded proteins that can mount UPR or facilitate their degradation through cellular degradation pathways.
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Affiliation(s)
- Amina R Gani
- Department of Biochemistry, University of Hyderabad, Hyderabad 500046, India
| | | | - Kolluru V A Ramaiah
- Department of Biochemistry, University of Hyderabad, Hyderabad 500046, India.
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21
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Kagawa T, Orii R, Hirose S, Arase Y, Shiraishi K, Mizutani A, Tsukamoto H, Mine T. Ursodeoxycholic acid stabilizes the bile salt export pump in the apical membrane in MDCK II cells. J Gastroenterol 2014; 49:890-9. [PMID: 23722250 DOI: 10.1007/s00535-013-0833-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 05/03/2013] [Indexed: 02/04/2023]
Abstract
BACKGROUND Ursodeoxycholic acid (UDCA) partly exerts choleretic effects by modifying the function of the bile salt export pump (Bsep, ABCB11). UDCA induces insertion of Bsep into the canalicular membrane of hepatocytes; however, underlying mechanisms remain unknown. We aimed to elucidate molecular mechanisms behind UDCA-induced Bsep activation. METHODS We established MDCK II cells stably expressing both Bsep and Na(+)-taurocholate cotransporting polypeptide, and investigated the effect of UDCA on activity and protein expression of Bsep using these cells. We performed inhibitor study to know the molecules involved in UDCA-induced Bsep activation, and also tested the influence of UDCA on Bsep having a disease-associated mutation. RESULTS UDCA activated Bsep in a dose-dependent manner. UDCA did not affect Bsep protein expression in whole cell lysates but increased its apical surface expression by extending the half-life from 2.4 to 5.0 h. This effect was specific to Bsep because UDCA did not affect other apical and basolateral proteins, and was independent of protein kinase A, adenylate cyclase, p38(MAPK), phosphatidylinositide 3-kinase, Ca(2+), and microtubules. NorUDCA activated Bsep similar to UDCA; however, cholic acid, taurocholic acid, and tauroUDCA had no effect. UDCA significantly increased the activity of Bsep with a benign recurrent intrahepatic cholestasis 2 mutation (A570T) but did not affect Bsep with a progressive familial intrahepatic cholestasis 2 mutation (G982R or D482G). CONCLUSIONS We demonstrated that UDCA stabilizes Bsep protein in the apical membrane and increases its activity in MDCK II cells, presumably by retarding the endocytotic process.
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Affiliation(s)
- Tatehiro Kagawa
- Division of Gastroenterology, Department of Internal Medicine, Tokai University School of Medicine, Shimokasuya 143, Isehara, Kanagawa, 259-1193, Japan,
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22
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Abstract
Bile acids, synthesized from cholesterol, are known to produce beneficial as well as toxic effects in the liver. The beneficial effects include choleresis, immunomodulation, cell survival, while the toxic effects include cholestasis, apoptosis and cellular toxicity. It is believed that bile acids produce many of these effects by activating intracellular signaling pathways. However, it has been a challenge to relate intracellular signaling to specific and at times opposing effects of bile acids. It is becoming evident that bile acids produce different effects by activating different isoforms of phosphoinositide 3-kinase (PI3K), Protein kinase Cs (PKCs), and mitogen activated protein kinases (MAPK). Thus, the apoptotic effect of bile acids may be mediated via PI3K-110γ, while cytoprotection induce by cAMP-GEF pathway involves activation of PI3K-p110α/β isoforms. Atypical PKCζ may mediate beneficial effects and nPKCε may mediate toxic effects, while cPKCα and nPKCδ may be involved in both beneficial and toxic effects of bile acids. The opposing effects of nPKCδ activation may depend on nPKCδ phosphorylation site(s). Activation of ERK1/2 and JNK1/2 pathway appears to mediate beneficial and toxic effects, respectively, of bile acids. Activation of p38α MAPK and p38β MAPK may mediate choleretic and cholestatic effects, respectively, of bile acids. Future studies clarifying the isoform specific effects on bile formation should allow us to define potential therapeutic targets in the treatment of cholestatic disorders.
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Affiliation(s)
- Mohammed Sawkat Anwer
- Department of Biomedical Sciences, Cummings School of Veterinary Medicine at Tufts University, 200 Westboro Road, North Grafton, MA, USA
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23
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Abstract
PURPOSE OF REVIEW TGR5 (Gpbar-1) is an emerging drug target for metabolic, intestinal and liver diseases. In liver, the highest expression of TGR5 is found in biliary epithelial cells. This review focusses on the function of TGR5 in cholangiocytes and the potential role of the receptor in biliary diseases. RECENT FINDINGS TGR5 is localized in the primary cilium and the apical membrane domain of cholangiocytes, where the receptor exerts secretory, proliferative and antiapoptotic effects. Recent human and animal studies using bile acid analogues suggest a therapeutic potential for TGR5 in primary biliary cirrhosis but not in primary sclerosing cholangitis. SUMMARY TGR5 has protective functions in cholangiocytes. Further studies are needed to determine the therapeutic potential of TGR5 agonists and antagonists in biliary diseases.
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24
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Beuers U. β1 integrin is a long-sought sensor for tauroursodeoxycholic acid. Hepatology 2013; 57:867-9. [PMID: 23456677 DOI: 10.1002/hep.26228] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 09/05/2012] [Indexed: 01/20/2023]
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25
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Gohlke H, Schmitz B, Sommerfeld A, Reinehr R, Häussinger D. α5 β1-integrins are sensors for tauroursodeoxycholic acid in hepatocytes. Hepatology 2013; 57:1117-29. [PMID: 22865233 DOI: 10.1002/hep.25992] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 07/21/2012] [Indexed: 01/02/2023]
Abstract
UNLABELLED Ursodeoxycholic acid, which in vivo is converted to its taurine conjugate tauroursodeoxycholic acid (TUDC), is a mainstay for the treatment of cholestatic liver disease. Earlier work showed that TUDC exerts its choleretic properties in the perfused rat liver in an α5 β1 integrin-mediated way. However, the molecular basis of TUDC-sensing in the liver is unknown. We herein show that TUDC (20 μmol/L) induces in perfused rat liver and human HepG2 cells the rapid appearance of the active conformation of the β1 subunit of α5 β1 integrins, followed by an activating phosphorylation of extracellular signal-regulated kinases. TUDC-induced kinase activation was no longer observed after β1 integrin knockdown in isolated rat hepatocytes or in the presence of an integrin-antagonistic hexapeptide in perfused rat liver. TUDC-induced β1 integrin activation occurred predominantly inside the hepatocyte and required TUDC uptake by way of the Na(+) /taurocholate cotransporting peptide. Molecular dynamics simulations of a 3D model of α5 β1 integrin with TUDC bound revealed significant conformational changes within the head region that have been linked to integrin activation before. CONCLUSIONS TUDC can directly activate intrahepatocytic β1 integrins, which trigger signal transduction pathways toward choleresis. (HEPATOLOGY 2013).
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Affiliation(s)
- Holger Gohlke
- Institute for Pharmaceutical and Medicinal Chemistry, Department of Mathematics and Natural Sciences, Heinrich-Heine-University Düsseldorf, Germany
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26
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Halilbasic E, Claudel T, Trauner M. Bile acid transporters and regulatory nuclear receptors in the liver and beyond. J Hepatol 2013; 58:155-68. [PMID: 22885388 PMCID: PMC3526785 DOI: 10.1016/j.jhep.2012.08.002] [Citation(s) in RCA: 265] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 08/01/2012] [Accepted: 08/03/2012] [Indexed: 02/06/2023]
Abstract
Bile acid (BA) transporters are critical for maintenance of the enterohepatic BA circulation where BAs exert their multiple physiological functions including stimulation of bile flow, intestinal absorption of lipophilic nutrients, solubilization and excretion of cholesterol, as well as antimicrobial and metabolic effects. Tight regulation of BA transporters via nuclear receptors is necessary to maintain proper BA homeostasis. Hereditary and acquired defects of BA transporters are involved in the pathogenesis of several hepatobiliary disorders including cholestasis, gallstones, fatty liver disease and liver cancer, but also play a role in intestinal and metabolic disorders beyond the liver. Thus, pharmacological modification of BA transporters and their regulatory nuclear receptors opens novel treatment strategies for a wide range of disorders.
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Key Words
- bile acids, cholestasis, fatty liver disease, gallstones, liver regeneration, liver cancer
- 6-ecdca, 6-ethylchenodeoxycholic acid
- ae2, anion exchanger 2
- abcg5/8, cholesterol efflux pump, atp-binding cassette, subfamily g, member 5/8
- ba, bile acid
- ampk, amp activated protein kinase
- bcrp (abcg2), breast cancer resistance protein, atp-binding cassette, subfamily g, member 2
- bric, benign recurrent intrahepatic cholestasis
- bsep (abcb11), bile salt export pump
- car (nr1i3), constitutive androstane receptor
- egfr, epidermal growth factor receptor
- fgf15/19, fibroblast growth factor 15/19
- fxr (nr1h4), farnesoid x receptor/bile acid receptor
- glp-1, glucagon like peptide 1
- gr (nr3c1), glucocorticoid receptor
- hcc, hepatocellular carcinoma
- hnf1α, hepatocyte nuclear factor 1 alpha
- hnf4α (nr2a1), hepatocyte nuclear factor 4 alpha
- ibabp (fabp6, ilbp), intestinal bile acid-binding protein, fatty acid-binding protein 6
- icp, intrahepatic cholestasis of pregnancy
- il6, interleukin 6
- lca, lithocholic acid
- lrh-1 (nr5a2), liver receptor homolog-1
- lxrα (nr1h3), liver x receptor alpha
- mdr1 (abcb1), p-glycoprotein, atp-binding cassette, subfamily b, member 1
- mdr2/mdr3 (abcb4), multidrug resistance protein 2 (rodents)/3 (human)
- mrp2 (abcc2), multidrug resistance-associated protein 2, atp-binding cassette, subfamily c, member 2
- mrp3 (abcc3), multidrug resistance-associated protein 3, atp-binding cassette, subfamily c, member 3
- mrp4 (abcc4), multidrug resistance-associated protein 4, atp-binding cassette, subfamily c, member 4
- nafld, non-alcoholic fatty liver disease
- nash, non-alcoholic steatohepatitis
- norudca, norursodeoxycholic acid
- nr, nuclear receptor
- ntcp (slc10a1), sodium/taurocholate cotransporting polypeptide, solute carrier family 10, member 1
- oatp1a2 (slco1a2, oatp1, oatp-a, slc21a3), solute carrier organic anion transporter family, member 1a2
- oatp1b1 (slco1b1, oatp2, oatp-c, slc21a6), solute carrier organic anion transporter family, member 1b1
- oatp1b3 (slco1b3, oatp8, slc21a8), solute carrier organic anion transporter family, member 1b3
- ostαβ, organic solute transporter alpha/beta
- pbc, primary biliary cirrhosis
- pfic, progressive familial intrahepatic cholestasis
- ph, partial hepatectomy
- pparα (nr1c1), peroxisome proliferator-activated receptor alpha
- pparγ (nr1c3), peroxisome proliferator-activated receptor gamma
- psc, primary sclerosing cholangitis
- pxr (nr1i2), pregnane x receptor
- rarα (nr1b1), retinoic acid receptor alpha
- rxrα (nr2b1), retinoid x receptor alpha
- shp (nr0b2), short heterodimer partner
- src2, p160 steroid receptor coactivator
- tgr5, g protein-coupled bile acid receptor
- tnfα, tumor necrosis factor α
- tpn, total parenteral nutrition
- udca, ursodeoxycholic acid
- vdr (nr1i1), vitamin d receptor. please note that for the convenience of better readability and clarity, abbreviations for transporters and nuclear receptors were capitalized throughout this article when symbols were identical for human and rodents
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Affiliation(s)
| | | | - Michael Trauner
- Corresponding author. Address: Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Waehringer Waehringer Guertel 18-20, A-1090 Vienna, Austria. Tel.: +43 01 40400 4741; fax: +43 01 40400 4735.
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Mühlfeld S, Domanova O, Berlage T, Stross C, Helmer A, Keitel V, Häussinger D, Kubitz R. Short-term feedback regulation of bile salt uptake by bile salts in rodent liver. Hepatology 2012; 56:2387-97. [PMID: 22806967 DOI: 10.1002/hep.25955] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 06/18/2012] [Indexed: 12/17/2022]
Abstract
UNLABELLED The sodium taurocholate cotransporting polypeptide (Ntcp) is the major bile salt uptake transporter at the sinusoidal membrane of hepatocytes. Short-term feedback regulation of Ntcp by primary bile salts has not yet been investigated in vivo. Subcellular localization of Ntcp was analyzed in Ntcp-transfected HepG2-cells by flow cytometry and in immunofluorescence images from tissue sections by a new automated image analysis method. Net bile salt uptake was investigated in perfused rat liver by a pulse chase technique. In Flag-Ntcp-EGFP (enhanced green fluorescent protein) expressing HepG2-cells, taurochenodeoxycholate (TCDC), but not taurocholate (TC), induced endocytosis of Ntcp. TCDC, but not TC, caused significant internalization of Ntcp in perfused rat livers, as shown by an increase in intracellular Ntcp immunoreactivity, whereas Bsep distribution remained unchanged. These results correlate with functional studies. Rat livers were continuously perfused with 100 μmol/L of TC. 25 μmol/L of TCDC, taurodeoxycholate (TDC), tauroursodeoxycholate (TUDC), or TC were added for 30 minutes, washed out, followed by a pulse of (3) [H]-TC. TCDC, but not TDC, TUDC, or TC significantly increased the amount of (3) [H]-TC in the effluent, indicating a reduced sinusoidal net TC uptake. This effect was sensitive to chelerythrine (protein kinase C inhibitor) and cypermethrin (protein phosphatase 2B inhibitor). Phosphoinositide 3-kinase (PI3K) inhibitors had an additive effect, whereas Erk1/2 (extracellular signal activated kinase 1/2), p38MAPK, protein phosphatase 1/2A (PP1/2A), and reactive oxygen species (ROS) were not involved. CONCLUSION TCDC regulates bile salt transport at the sinusoidal membrane by protein kinase C- and protein phosphatase 2B-mediated retrieval of Ntcp from the plasma membrane. During increased portal bile salt load this mechanism may adjust bile salt uptake along the acinus and protect periportal hepatocytes from harmful bile salt concentrations.
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Affiliation(s)
- Stefanie Mühlfeld
- Department of Gastroenterology, Hepatology and Infectious Diseases, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
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Boaglio AC, Zucchetti AE, Toledo FD, Barosso IR, Sánchez Pozzi EJ, Crocenzi FA, Roma MG. ERK1/2 and p38 MAPKs are complementarily involved in estradiol 17ß-D-glucuronide-induced cholestasis: crosstalk with cPKC and PI3K. PLoS One 2012; 7:e49255. [PMID: 23166621 PMCID: PMC3498151 DOI: 10.1371/journal.pone.0049255] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 10/04/2012] [Indexed: 12/17/2022] Open
Abstract
Objective The endogenous, cholestatic metabolite estradiol 17ß-d-glucuronide (E217G) induces endocytic internalization of the canalicular transporters relevant to bile formation, Bsep and Mrp2. We evaluated here whether MAPKs are involved in this effect. Design ERK1/2, JNK1/2, and p38 MAPK activation was assessed by the increase in their phosphorylation status. Hepatocanalicular function was evaluated in isolated rat hepatocyte couplets (IRHCs) by quantifying the apical secretion of fluorescent Bsep and Mrp2 substrates, and in isolated, perfused rat livers (IPRLs), using taurocholate and 2,4-dinitrophenyl-S-glutathione, respectively. Protein kinase participation in E217G-induced secretory failure was assessed by co-administering selective inhibitors. Internalization of Bsep/Mrp2 was assessed by confocal microscopy and image analysis. Results E217G activated all kinds of MAPKs. The PI3K inhibitor wortmannin prevented ERK1/2 activation, whereas the cPKC inhibitor Gö6976 prevented p38 activation, suggesting that ERK1/2 and p38 are downstream of PI3K and cPKC, respectively. The p38 inhibitor SB203580 and the ERK1/2 inhibitor PD98059, but not the JNK1/2 inhibitor SP600125, partially prevented E217G-induced changes in transporter activity and localization in IRHCs. p38 and ERK1/2 co-inhibition resulted in additive protection, suggesting complementary involvement of these MAPKs. In IPRLs, E217G induced endocytosis of canalicular transporters and a rapid and sustained decrease in bile flow and biliary excretion of Bsep/Mrp2 substrates. p38 inhibition prevented this initial decay, and the internalization of Bsep/Mrp2. Contrarily, ERK1/2 inhibition accelerated the recovery of biliary secretion and the canalicular reinsertion of Bsep/Mrp2. Conclusions cPKC/p38 MAPK and PI3K/ERK1/2 signalling pathways participate complementarily in E217G-induced cholestasis, through internalization and sustained intracellular retention of canalicular transporters, respectively.
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Affiliation(s)
| | | | | | | | | | - Fernando A. Crocenzi
- Institute of Experimental Physiology, National Scientific and Technical Research Council/National University of Rosario, Rosario, Argentina
- * E-mail: (FAC); (MGR)
| | - Marcelo G. Roma
- Institute of Experimental Physiology, National Scientific and Technical Research Council/National University of Rosario, Rosario, Argentina
- * E-mail: (FAC); (MGR)
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Perspective: TGR5 (Gpbar-1) in liver physiology and disease. Clin Res Hepatol Gastroenterol 2012; 36:412-9. [PMID: 22521118 DOI: 10.1016/j.clinre.2012.03.008] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Accepted: 03/02/2012] [Indexed: 02/06/2023]
Abstract
Bile acids are signaling molecules with diverse endocrine functions. Bile acid effects are mediated through the nuclear receptor farnesoid X receptor (FXR), the G-protein coupled receptor TGR5 (Gpbar-1) and various other bile acid sensing molecules. TGR5 is almost ubiquitously expressed and has been detected in different non-parenchymal cells of human and rodent liver. Here, TGR5 has anti-inflammatory, anti-apoptotic and choleretic functions. Mice with targeted deletion of TGR5 are protected from the development of cholesterol gallstones. Administration of specific TGR5 agonists lowers serum and liver triglyceride levels thereby reducing liver steatosis. Furthermore, activation of TGR5 promotes intestinal glucagon-like peptide-1 (GLP-1) release, thereby modulating glucose homeostasis and energy expenditure in brown adipose tissue and skeletal muscle. Additionally, TGR5 exerts anti-inflammatory actions resulting in decreased liver injury in animal models of sepsis. These beneficial effects make TGR5 an attractive therapeutic target for metabolic diseases, such as diabetes, obesity, atherosclerosis and steatohepatitis.
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Cantore M, Reinehr R, Sommerfeld A, Becker M, Häussinger D. The Src family kinase Fyn mediates hyperosmolarity-induced Mrp2 and Bsep retrieval from canalicular membrane. J Biol Chem 2011; 286:45014-29. [PMID: 22057277 PMCID: PMC3247936 DOI: 10.1074/jbc.m111.292896] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 10/23/2011] [Indexed: 12/17/2022] Open
Abstract
In perfused rat liver, hyperosmolarity induces Mrp2- (Kubitz, R., D'urso, D., Keppler, D., and Häussinger, D. (1997) Gastroenterology 113, 1438-1442) and Bsep retrieval (Schmitt, M., Kubitz, R., Lizun, S., Wettstein, M., and Häussinger, D. (2001) Hepatology 33, 509-518) from the canalicular membrane leading to cholestasis. The aim of this study was to elucidate the underlying signaling events. Hyperosmolarity-induced retrieval of Mrp2 and Bsep from the canalicular membrane in perfused rat liver was accompanied by an activating phosphorylation of the Src kinases Fyn and Yes but not of c-Src. Both hyperosmotic transporter retrieval and Src kinase activation were sensitive to apocynin (300 μmol/liter), N-acetylcysteine (NAC; 10 mmol/liter), and SU6656 (1 μmol/liter). Also PP-2 (250 nmol/liter), which inhibited hyperosmotic Fyn but not Yes activation, prevented hyperosmotic transporter retrieval from the canalicular membrane, suggesting that Fyn but not Yes mediates hyperosmotic Bsep and Mrp2 retrieval. Neither hyperosmotic Fyn activation nor Bsep/Mrp2 retrieval was observed in livers from p47(phox) knock-out mice. Hyperosmotic activation of JNKs was sensitive to apocynin and NAC but insensitive to SU6656 and PP-2, indicating that JNKs are not involved in transporter retrieval, as also evidenced by experiments using the JNK inhibitors L-JNKI-1 and SP6001255, respectively. Hyperosmotic transporter retrieval was accompanied by a NAC and Fyn knockdown-sensitive inhibition of biliary excretion of the glutathione conjugate of 1-chloro-2,4-dinitrobenzene in perfused rat liver and of cholyl-L-lysyl-fluorescein secretion into the pseudocanaliculi formed by hepatocyte couplets. Hyperosmolarity triggered an association between Fyn and cortactin and increased the amount of phosphorylated cortactin underneath the canalicular membrane. It is concluded that the hyperosmotic cholestasis is triggered by a NADPH oxidase-driven reactive oxygen species formation that mediates Fyn-dependent retrieval of the Mrp2 and Bsep from the canalicular membrane, which may involve an increased cortactin phosphorylation.
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Affiliation(s)
- Miriam Cantore
- From the Clinic for Gastroenterology, Hepatology, and Infectiology, Heinrich-Heine-University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Roland Reinehr
- From the Clinic for Gastroenterology, Hepatology, and Infectiology, Heinrich-Heine-University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Annika Sommerfeld
- From the Clinic for Gastroenterology, Hepatology, and Infectiology, Heinrich-Heine-University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Martin Becker
- From the Clinic for Gastroenterology, Hepatology, and Infectiology, Heinrich-Heine-University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Dieter Häussinger
- From the Clinic for Gastroenterology, Hepatology, and Infectiology, Heinrich-Heine-University Düsseldorf, D-40225 Düsseldorf, Germany
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Reinehr R, Häussinger D. CD95 death receptor and epidermal growth factor receptor (EGFR) in liver cell apoptosis and regeneration. Arch Biochem Biophys 2011; 518:2-7. [PMID: 22182753 DOI: 10.1016/j.abb.2011.12.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 11/29/2011] [Accepted: 12/04/2011] [Indexed: 02/08/2023]
Abstract
Recent evidence suggests that signaling pathways towards cell proliferation and cell death are much more interconnected than previously thought. Whereas not only death receptors such as CD95 (Fas, APO-1) can couple to both, cell death and proliferation, also growth factor receptors such as the epidermal growth factor receptor (EGFR) are involved in these opposing kinds of cell fate. EGFR is briefly discussed as a growth factor receptor involved in liver cell proliferation during liver regeneration. Then the role of EGFR in activating CD95 death receptor in liver parenchymal cells (PC) and hepatic stellate cells (HSC), which represent a liver stem/progenitor cell compartment, is described summarizing different ways of CD95- and EGFR-dependent signaling in the liver. Here, depending on the hepatic cell type (PC vs. HSC) and the respective signaling context (sustained vs. transient JNK activation) CD95-/EGFR-mediated signaling ends up in either liver cell apoptosis or cell proliferation.
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Affiliation(s)
- Roland Reinehr
- Heinrich-Heine-University Düsseldorf, Clinic for Gastroenterology, Hepatology and Infectious Diseases, Germany.
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Ursodeoxycholic acid in cholestasis: linking action mechanisms to therapeutic applications. Clin Sci (Lond) 2011; 121:523-44. [PMID: 21854363 DOI: 10.1042/cs20110184] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
UDCA (ursodeoxycholic acid) is the therapeutic agent most widely used for the treatment of cholestatic hepatopathies. Its use has expanded to other kinds of hepatic diseases, and even to extrahepatic ones. Such versatility is the result of its multiple mechanisms of action. UDCA stabilizes plasma membranes against cytolysis by tensioactive bile acids accumulated in cholestasis. UDCA also halts apoptosis by preventing the formation of mitochondrial pores, membrane recruitment of death receptors and endoplasmic-reticulum stress. In addition, UDCA induces changes in the expression of metabolizing enzymes and transporters that reduce bile acid cytotoxicity and improve renal excretion. Its capability to positively modulate ductular bile flow helps to preserve the integrity of bile ducts. UDCA also prevents the endocytic internalization of canalicular transporters, a common feature in cholestasis. Finally, UDCA has immunomodulatory properties that limit the exacerbated immunological response occurring in autoimmune cholestatic diseases by counteracting the overexpression of MHC antigens and perhaps by limiting the production of cytokines by immunocompetent cells. Owing to this multi-functionality, it is difficult to envisage a substitute for UDCA that combines as many hepatoprotective effects with such efficacy. We predict a long-lasting use of UDCA as the therapeutic agent of choice in cholestasis.
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Graf D, Haselow K, Münks I, Bode JG, Häussinger D. Inhibition of interferon-α-induced signaling by hyperosmolarity and hydrophobic bile acids. Biol Chem 2011; 391:1175-87. [PMID: 21028968 DOI: 10.1515/bc.2010.108] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Apart from viral conditions, host factors such as elevated bile acid concentrations are determinants of successful interferon-α (IFN-α) treatment in patients with chronic hepatitis C or B. The present study demonstrates that hydrophobic bile acids inhibit Jak1- and Tyk2-phosphorylation, which lead to blockade of STAT1-mediated IFN-α-signaling in the sodium-taurocholate cotransporting peptide (NTCP)-transfected human hepatoma cell line HepG2, resulting in a decreased mRNA and protein expression of IFN-stimulated genes such as myxovirus resistance protein A (MxA) or dsRNA-activated protein kinase (PKR). In addition, hyperosmotic stress leads to an inhibition of IFN-α-induced Jak1- and Tyk2-phosphorylation, and STAT1/STAT2-phosphorylation and gene expression. This inhibitory effect of hydrophobic bile acids or hyperosmolarity is not due to caspase-mediated cleavage or lysosomal degradation of the cognate receptors or to the generation of oxidative stress, activation of p38- or Erk-mediated MAPK pathways or phosphatase activity. Preincubation with the organic osmolyte betaine blocked the inhibitory effect of bile acids or hyperosmolarity on MxA protein expression, but had no effect on transcript levels or activation of STAT1, suggesting that betaine mediates its effects on MxA expression at a translational or post-translational level. Our findings could provide a rationale for betaine use in cholestatic HBV/HCV patients undergoing interferon therapy.
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Affiliation(s)
- Dirk Graf
- Department of Gastroenterology, Hepatology and Infectiology, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany.
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Stross C, Keitel V, Winands E, Häussinger D, Kubitz R. Expression and localization of atypical PKC isoforms in liver parenchymal cells. Biol Chem 2009; 390:235-44. [PMID: 19090727 DOI: 10.1515/bc.2009.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Members of all three classes of the protein kinase C (PKC) family including atypical PKCzeta (PKCzeta) are involved in central functions of liver parenchymal cells. However, expression and localization of PKCiota (PKCiota), the highly homologous atypical PKC (aPKC) isoform, in hepatocytes is unknown to date. PKCzeta and PKCiota were cloned from human and rat liver and fused to fluorescent protein tags (YFP). The sequence of full-length rat PKCiota is not yet known and was cloned from cDNA of hepatocytes by the use of degenerated primers. PKCzeta-YFP and PKCiota-YFP (human and rat) were expressed in HeLa or HEK293 cells and used to test the specificity of seven aPKC antibodies. Two antibodies were PKCiota-specific and two were specific for PKCzeta in immunofluorescence and Western blot analysis. Subcellular localization was analyzed by immunofluorescence in isolated rat and human hepatocytes and liver sections. Low immunoreactivity for aPKCs was found at the sinusoidal membrane and in the cytosol. The highest density of PKCiota as well as PKCzeta was found at the canalicular membrane in co-localization with ABC-transporters, such as bile salt export pump or multidrug resistance-associated protein 2. This topology suggests a specific function of aPKCs at the canalicular membrane in addition to their known role in cell polarity of epithelial cells.
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Affiliation(s)
- Claudia Stross
- Clinic for Gastroenterology, Hepatology and Infectiology, Heinrich Heine University Düsseldorf, D-40225 Düsseldorf, Germany
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Roma MG, Crocenzi FA, Mottino AD. Dynamic localization of hepatocellular transporters in health and disease. World J Gastroenterol 2008; 14:6786-801. [PMID: 19058304 PMCID: PMC2773873 DOI: 10.3748/wjg.14.6786] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Vesicle-based trafficking of hepatocellular transporters involves delivery of the newly-synthesized carriers from the rough endoplasmic reticulum to either the plasma membrane domain or to an endosomal, submembrane compartment, followed by exocytic targeting to the plasma membrane. Once delivered to the plasma membrane, the transporters usually undergo recycling between the plasma membrane and the endosomal compartment, which usually serves as a reservoir of pre-existing transporters available on demand. The balance between exocytic targeting and endocytic internalization from/to this recycling compartment is therefore a chief determinant of the overall capability of the liver epithelium to secrete bile and to detoxify endo and xenobiotics. Hence, it is a highly regulated process. Impaired regulation of this balance may lead to abnormal localization of these transporters, which results in bile secretory failure due to endocytic internalization of key transporters involved in bile formation. This occurs in several experimental models of hepatocellular cholestasis, and in most human cholestatic liver diseases. This review describes the molecular bases involved in the biology of the dynamic localization of hepatocellular transporters and its regulation, with a focus on the involvement of signaling pathways in this process. Their alterations in different experimental models of cholestasis and in human cholestatic liver disease are reviewed. In addition, the causes explaining the pathological condition (e.g. disorganization of actin or actin-transporter linkers) and the mediators involved (e.g. activation of cholestatic signaling transduction pathways) are also discussed. Finally, several experimental therapeutic approaches based upon the administration of compounds known to stimulate exocytic insertion of canalicular transporters (e.g. cAMP, tauroursodeoxycholate) are described.
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Abstract
Bile acids are not only important for the absorption of dietary lipids and fat soluble vitamins but are signalling molecules with diverse endocrine and paracrine functions. Bile acids regulate bile acid, lipid and glucose metabolism and modulate temperature and energy homeostasis. Furthermore, bile acids can not only promote cell proliferation and liver regeneration but can also induce programmed cell death. Bile acid functions are mediated through different pathways which comprise the activation of nuclear hormone receptors, of intracellular kinases and of the plasma membrane-bound, G-protein coupled bile acid receptor TGR5/Gpbar-1.
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Denk GU, Hohenester S, Wimmer R, Böhland C, Rust C, Beuers U. Role of mitogen-activated protein kinases in tauroursodeoxycholic acid-induced bile formation in cholestatic rat liver. Hepatol Res 2008; 38:717-26. [PMID: 18328068 DOI: 10.1111/j.1872-034x.2008.00321.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM Ursodeoxycholic acid exerts anticholestatic effects in various cholestatic disorders and experimental models of cholestasis. Its taurine conjugate (TUDCA) stimulates bile salt secretion in isolated perfused rat livers (IPRL) under physiological, non-cholestatic conditions, in part by mitogen-activated protein kinase (MAPK)-dependent mechanisms. The role of MAPK in the anticholestatic effect of TUDCA, however, is unclear. Therefore, we studied the role of MAPK in the anticholestatic effect of TUDCA in IPRL and isolated rat hepatocytes (IRH) in taurolithocholic acid (TLCA)-induced cholestasis. METHODS Bile flow, biliary levels of 2,4-dinitrophenyl-S-glutathione (GS-DNP) as a marker of hepatobiliary organic anion secretion and activity of lactate dehydrogenase (LDH) in hepatovenous effluate as a marker of hepatocellular damage in IPRL perfused with TUDCA and/or TLCA were determined in the presence or absence of MAPK inhibitors. In addition, phosphorylation of Erk 1/2 and p38(MAPK) induced by TUDCA and/or TLCA was studied by Western immunoblot in IPRL and IRH. RESULTS TUDCA-induced bile flow was impaired by the Erk 1/2 inhibitor PD98059 in normal livers (-28%), but not in livers made cholestatic by TLCA. GS-DNP secretion was unaffected by PD98059 under both conditions. TUDCA-induced bile formation and organic anion secretion both in the presence and absence of TLCA were unaffected by the p38(MAPK) inhibitor SB202190. Erk 1/2 phosphorylation in liver tissue was unchanged after bile salt exposure for 70 min, but was transiently enhanced by TUDCA in IRH. CONCLUSION MAPK do not mediate the anticholestatic effects of TUDCA in TLCA-induced cholestasis.
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Affiliation(s)
- Gerald Ulrich Denk
- Department of Medicine II-Grosshadern, Klinikum of the University of Munich, Munich, Germany
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Keitel V, Donner M, Winandy S, Kubitz R, Häussinger D. Expression and function of the bile acid receptor TGR5 in Kupffer cells. Biochem Biophys Res Commun 2008; 372:78-84. [DOI: 10.1016/j.bbrc.2008.04.171] [Citation(s) in RCA: 293] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Accepted: 04/28/2008] [Indexed: 02/07/2023]
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Hepatocellular transport in acquired cholestasis: new insights into functional, regulatory and therapeutic aspects. Clin Sci (Lond) 2008; 114:567-88. [PMID: 18377365 DOI: 10.1042/cs20070227] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The recent overwhelming advances in molecular and cell biology have added enormously to our understanding of the physiological processes involved in bile formation and, by extension, to our comprehension of the consequences of their alteration in cholestatic hepatopathies. The present review addresses in detail this new information by summarizing a number of recent experimental findings on the structural, functional and regulatory aspects of hepatocellular transporter function in acquired cholestasis. This comprises (i) a short overview of the physiological mechanisms of bile secretion, including the nature of the transporters involved and their role in bile formation; (ii) the changes induced by nuclear receptors and hepatocyte-enriched transcription factors in the constitutive expression of hepatocellular transporters in cholestasis, either explaining the primary biliary failure or resulting from a secondary adaptive response; (iii) the post-transcriptional changes in transporter function and localization in cholestasis, including a description of the subcellular structures putatively engaged in the endocytic internalization of canalicular transporters and the involvement of signalling cascades in this effect; and (iv) a discussion on how this new information has contributed to the understanding of the mechanism by which anticholestatic agents exert their beneficial effects, or the manner in which it has helped the design of new successful therapeutic approaches to cholestatic liver diseases.
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Reinehr R, Häussinger D. CD95 activation in the liver: ion fluxes and oxidative signaling. Arch Biochem Biophys 2007; 462:124-31. [PMID: 17258167 DOI: 10.1016/j.abb.2006.12.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2006] [Revised: 12/14/2006] [Accepted: 12/16/2006] [Indexed: 12/18/2022]
Abstract
Apoptosis is characterized by typical features as cell shrinkage, nuclear condensation, DNA fragmentation, and apoptotic body formation. Whereas some signs of apoptosis are cell type-and death signal-dependent, apoptotic cell volume decrease is an early and ubiquitous event and little is known about the signalling events, which are localized upstream of the plasma membrane transport steps leading to apoptotic cell volume decrease and the proapoptotic events, which are induced by osmolyte loss and cell shrinkage. Ion fluxes and oxidative signaling were recently shown to play an important role in signal transduction with respect to apoptotic cell death within the liver, as a ceramide-dependent activation of the NADPH oxidase was identified as the source of reactive oxygen species generation in rat hepatocytes upon treatment with CD95 ligand, hydrophobic bile salts or hyperosmolarity. The NADPH oxidase-derived ROS signal then allows via Yes, JNK, and EGFR activation for CD95 tyrosine phosphorylation as a prerequisite for CD95 targeting to the plasma membrane and formation of the death inducing signalling complex. Other covalent modifications such as CD95-tyrosine-nitration or CD95-serine/threonine-phosphorylation can interfere with the CD95 activation process. The findings not only provide a mechanistic explanation for the high susceptibility of dehydrated cells for apoptosis, but also give insight into the role of ion fluxes and oxidative signaling with respect to apoptotic cell death within the liver.
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Affiliation(s)
- Roland Reinehr
- Clinic for Gastroenterology, Hepatology and Infectiology, Heinrich-Heine-University, Düsseldorf, Germany
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Graf D, Kohlmann C, Haselow K, Gehrmann T, Bode JG, Häussinger D. Bile acids inhibit interleukin-6 signaling via gp130 receptor-dependent and -independent pathways in rat liver. Hepatology 2006; 44:1206-17. [PMID: 17058237 DOI: 10.1002/hep.21368] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Interleukin-6 (IL-6) is a major regulator of the acute phase reaction in the liver and is thought to mediate protective effects in response to hepatotoxins. In this study, the influence of bile acids on IL-6 signal transduction was analyzed. It was shown that hydrophobic bile acids such as glycochenodeoxycholate (GCDC) inhibited IL-6-induced tyrosine phosphorylation of signal transducer and activator of transcription (STAT) 3 in hepatocytes and in perfused rat liver. This inhibition was accompanied by GCDC-mediated downregulation of glycoprotein (gp) 130 expression, whereas gp130 and suppressor of cytokine signaling 3 messenger RNA and gp80 protein levels remained unaffected. The GCDC-induced downregulation of gp130 protein expression was insensitive to inhibition of proteasomal or lysosomal protein degradation but turned out to be sensitive to inhibition of caspase-3 or caspase-8 activity. Accordingly, treatment of cell extracts with active recombinant caspase-3 led to a decay of immunoreactive gp130. Moreover, activation of caspases by CD95 ligand or hyperosmotic stress also resulted in a downregulation of gp130 levels. This indicates that caspase activation antagonizes IL-6 signaling by decay of gp130 levels. However, caspase inhibition did not prevent GCDC-dependent inhibition of IL-6-induced STAT3 activation, which turned out to be at least partially sensitive to suppression of p38(MAPK) activation. In conclusion, hydrophobic bile acids compromise IL-6 signaling through both a caspase-mediated downregulation of gp130 and a p38(MAPK)-dependent inhibition of STAT3 phosphorylation. This may contribute to bile acid-induced hepatotoxicity in cholestasis through counteracting the known hepatoprotective effects of IL-6.
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Affiliation(s)
- Dirk Graf
- Department of Gastroenterology, Hepatology, and Infectiology, Heinrich-Heine University, Düsseldorf, Germany.
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Stieger B, Meier Y, Meier PJ. The bile salt export pump. Pflugers Arch 2006; 453:611-20. [PMID: 17051391 DOI: 10.1007/s00424-006-0152-8] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Accepted: 08/08/2006] [Indexed: 12/20/2022]
Abstract
Canalicular secretion of bile salts mediated by the bile salt export pump Bsep constitutes the major driving force for the generation of bile flow. Bsep is a member of the B-family of the super family of ATP-binding cassette transporters and is classified as ABCB11. Bsep has a narrow substrate specificity, which is largely restricted to bile salts. Bsep is extensively regulated at the transcriptional and posttranscriptional level, which directly modulates canalicular bile formation. Pathophysiological alterations of Bsep by either inherited mutations or acquired processes such as inhibition by drugs or disease-related down regulation may lead to a wide spectrum of mild to severe forms of liver disease. Furthermore, many genetic variants of Bsep are known, some of which potentially render individuals susceptible to acquired forms of liver disease.
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Affiliation(s)
- Bruno Stieger
- Department of Medicine, Institute of Clinical Pharmacology and Toxicology, University Hospital, Zürich, Switzerland.
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Beuers U. Drug insight: Mechanisms and sites of action of ursodeoxycholic acid in cholestasis. ACTA ACUST UNITED AC 2006; 3:318-28. [PMID: 16741551 DOI: 10.1038/ncpgasthep0521] [Citation(s) in RCA: 293] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Accepted: 04/06/2006] [Indexed: 12/18/2022]
Abstract
Ursodeoxycholic acid (UDCA) exerts anticholestatic effects in various cholestatic disorders. Several potential mechanisms and sites of action of UDCA have been unraveled in clinical and experimental studies, which could explain its beneficial effects. The relative contribution of these mechanisms to the anticholestatic action of UDCA depends on the type and stage of the cholestatic injury. In early-stage primary biliary cirrhosis and primary sclerosing cholangitis, protection of injured cholangiocytes against the toxic effects of bile acids might prevail. Stimulation of impaired hepatocellular secretion by mainly post-transcriptional mechanisms, including stimulation of synthesis, targeting and apical membrane insertion of key transporters, seems to be relevant in more advanced cholestasis. In intrahepatic cholestasis of pregnancy, stimulation of impaired hepatocellular secretion could be crucial for rapid relief of pruritus and improvement of serum liver tests, as it is in some forms of drug-induced cholestasis. In cystic fibrosis, stimulation of cholangiocellular calcium-dependent secretion of chloride and bicarbonate ions could have a major impact. Inhibition of bile-acid-induced hepatocyte apoptosis can have a role in all states of cholestasis that are characterized by hepatocellular bile-acid retention. Different mechanisms of action could, therefore, contribute to the beneficial effect of UDCA under various cholestatic conditions.
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Affiliation(s)
- Ulrich Beuers
- Department of Medicine II, Klinikum Grosshadern, University of Munich, Germany.
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Le M, Krilov L, Meng J, Chapin-Kennedy K, Ceryak S, Bouscarel B. Bile acids stimulate PKCalpha autophosphorylation and activation: role in the attenuation of prostaglandin E1-induced cAMP production in human dermal fibroblasts. Am J Physiol Gastrointest Liver Physiol 2006; 291:G275-87. [PMID: 16710050 DOI: 10.1152/ajpgi.00346.2005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The aim was to identify the specific PKC isoform(s) and their mechanism of activation responsible for the modulation of cAMP production by bile acids in human dermal fibroblasts. Stimulation of fibroblasts with 25-100 microM of chenodeoxycholic acid (CDCA) and ursodeoxycholic acid (UDCA) led to YFP-PKCalpha and YFP-PKCdelta translocation in 30-60 min followed by a transient 24- to 48-h downregulation of the total PKCalpha, PKCdelta, and PKCepsilon protein expression by 30-50%, without affecting that of PKCzeta. Increased plasma membrane translocation of PKCalpha was associated with an increased PKCalpha phosphorylation, whereas increased PKCdelta translocation to the perinuclear domain was associated with an increased accumulation of phospho-PKCdelta Thr505 and Tyr311 in the nucleus. The PKCalpha specificity on the attenuation of cAMP production by CDCA was demonstrated with PKC downregulation or inhibition, as well as PKC isoform dominant-negative mutants. Under these same conditions, neither phosphatidylinositol 3-kinase, p38 MAP kinase, p42/44 MAP kinase, nor PKA inhibitors had any significant effect on the CDCA-induced cAMP production attenuation. CDCA concentrations as low as 10 microM stimulated PKCalpha autophosphorylation in vitro. This bile acid effect required phosphatidylserine and was completely abolished by the presence of Gö6976. CDCA at concentrations less than 50 microM enhanced the PKCalpha activation induced by PMA, whereas greater CDCA concentrations reduced the PMA-induced PKCalpha activation. CDCA alone did not affect PKCalpha activity in vitro. In conclusion, although CDCA and UDCA activate different PKC isoforms, PKCalpha plays a major role in the bile acid-induced inhibition of cAMP synthesis in fibroblasts. This study emphasizes potential consequences of increased systemic bile acid concentrations and cellular bile acid accumulation in extrahepatic tissues during cholestatic liver diseases.
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Affiliation(s)
- Man Le
- Gastroenterology Research Laboratory, Department of Medicine, George Washington Univesity Medical Center, Washington, DC 20037, USA
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Abstract
Vanishing bile duct syndromes (VBDS) are characterized by progressive loss of small intrahepatic ducts caused by a variety of different diseases leading to chronic cholestasis, cirrhosis, and premature death from liver failure. The majority of adult patients with VBDS suffer from primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Ursodeoxycholic acid (UDCA), a hydrophilic dihydroxy bile acid, is the only drug currently approved for the treatment of patients with PBC, and anticholestatic effects have been reported for several other cholestatic syndromes. Several potential mechanisms of action of UDCA have been proposed including stimulation of hepatobiliary secretion, inhibition of apoptosis and protection of cholangiocytes against toxic effects of hydrophobic bile acids.
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Affiliation(s)
- Thomas Pusl
- Department of Medicine II, Klinikum Grosshadern, Marchioninistrasse 15, 81377 Munich, Germany
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Rust C, Beuers U. Medical treatment of primary biliary cirrhosis and primary sclerosing cholangitis. Clin Rev Allergy Immunol 2006; 28:135-45. [PMID: 15879619 DOI: 10.1385/criai:28:2:135] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Chronic cholestasis is the main feature of primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC), the most common chronic cholestatic liver diseases in adults. Although the etiology of both diseases remains poorly understood, auto-immune processes appear to be important, particularly in PBC. PBC and PSC usually slowly progress to cirrhosis,liver failure, and death, unless liver transplantation is performed. Ursodeoxycholic acid(UDCA), a hydrophilic dihydroxy bile acid, is the only drug currently approved for the treatment of patients with PBC and is also used in patients with PSC. In addition to UDCA, patients with PSC should be referred to endoscopic dilatation of major bile duct stenoses. Several potential mechanisms of action of UDCA have been proposed, including intracellular modulation of signaling events and secretion. Various immunosuppressive drugs have been evaluated alone or in combination with UDCA-especially for the treatment of PBC. Of these drugs,the topical corticosteroid budesonide, together with UDCA, appears promising in the treatment of early stage PBC, but data remain insufficient to warrant use of budesonide outside of controlled studies.
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Affiliation(s)
- Christian Rust
- Department of Internal Medicine II Grosshadern, University of Munich, Munich, Germany.
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Dombrowski F, Stieger B, Beuers U. Tauroursodeoxycholic acid inserts the bile salt export pump into canalicular membranes of cholestatic rat liver. J Transl Med 2006; 86:166-74. [PMID: 16344857 DOI: 10.1038/labinvest.3700371] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Ursodeoxycholic acid exerts anticholestatic effects in chronic cholestatic liver disease in humans as well as in experimental animal models of cholestasis. Its taurine conjugate, TUDCA, was recently shown to stimulate insertion of the apical conjugate export pump, Mrp2 (ABCC2), into canalicular membranes of rat hepatocytes made cholestatic by exposure to taurolithocholic acid (TLCA). The aim of this immunoelectronmicroscopic study was to test whether TLCA and TUDCA modulate the canalicular density of the other key apical transporter, the bile salt export pump, Bsep (ABCB11), in a similar way. Immunoelectronmicroscopic analysis of Bsep density on canalicular membranes, microvilli, and pericanalicular area of hepatocytes was performed in rat liver tissue prepared after liver perfusion with bile acids or carrier medium only. TLCA (10 micromol/l for 50 min) decreased Bsep density in canalicular membranes to 31% of controls (P<0.05) when bile flow was reduced to 35% of controls (P<0.05). Concomitantly, Bsep density in a 1 microm pericanalicular zone increased to 202% (P<0.05) indicating effective retrieval of Bsep from the canalicular membrane induced by TLCA. Coadministration of TUDCA (25 micromol/l) led to a 3.2-fold increase of Bsep density in canalicular membranes equal to control liver (P<0.05 vs TLCA) in association with a 3.8-fold increase of bile flow (P<0.05 vs TLCA). Stimulation of apical membrane insertion of key transporters like the bile salt export pump, Bsep, and-as previously shown-the conjugate export pump, Mrp2, may contribute to the anticholestatic action of UDCA amides in cholestatic conditions.
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Affiliation(s)
- Frank Dombrowski
- Department of Pathology, University of Magdeburg, Magdeburg, Germany
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Pütz G, Schmider W, Nitschke R, Kurz G, Blum HE. Synthesis of phospholipid-conjugated bile salts and interaction of bile salt-coated liposomes with cultured hepatocytes. J Lipid Res 2005; 46:2325-38. [PMID: 16150831 DOI: 10.1194/jlr.m500144-jlr200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
To examine the possibility of targeting liposomes to hepatocytes via bile salts, the bile salt lithocholyltaurine was covalently linked to a phospholipid. The isomeric compounds disodium 3alpha-(2-(1,2-O-distearoyl-sn-glycero-3-phospho-2'-ethanolamidosuccinyloxy)ethoxy)-5beta-cholan-24-oyl-2'-aminoethansulfonate and disodium 3beta-(2-(1,2-O-distearoyl-sn-glycero-3-phospho-2'-ethanolamidosuccinyloxy)ethoxy-5beta-cholan-24-oyl-2'-aminoethansulfonate (DSPE-3beta-LCT) were synthesized and incorporated into liposomal membranes. Confocal laser scanning microscopy studies showed that bile salt-bearing liposomes (BSLs) attach to the surface of rat hepatocytes in culture. Studies with radioactively labeled liposomes revealed that the bile salt linked via the 3beta-conformation resulted in a higher attachment efficiency than that with the 3alpha-derivative. In the presence of BSLs corresponding to 2 mM liposomal phosphatidylcholine, uptake of 50 microM cholyltaurine (CT) into hepatocytes was reduced by approximately 40% by the 3beta-derivative and by approximately 17% by the 3alpha-derivative. When added simultaneously with the liposomes, CT up to 75 microM inhibited the binding of DSPE-3beta-LCT-bearing liposomes. By contrast, increasing concentrations reversed this inhibition and resulted in an increased bile salt-mediated binding. The same was true when CT was added 10 min before the liposomes were added. The attachment of BSLs to the surface of hepatocytes opens up promising possibilities for hepatocyte-specific drug delivery. More generally, not only substrates for cellular endocytosing receptors but also substrates for cellular carrier proteins should be suitable ligands for the cell-specific targeting of nanoscale particles such as liposomes.
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Affiliation(s)
- G Pütz
- University Medical Clinic Freiburg, D-79106 Freiburg, Germany.
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Bile acids induce mitochondrial ROS, which promote activation of receptor tyrosine kinases and signaling pathways in rat hepatocytes. Hepatology 2004. [DOI: 10.1002/hep.1840400427] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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Fang Y, Han SI, Mitchell C, Gupta S, Studer E, Grant S, Hylemon PB, Dent P. Bile acids induce mitochondrial ROS, which promote activation of receptor tyrosine kinases and signaling pathways in rat hepatocytes. Hepatology 2004; 40:961-71. [PMID: 15382121 DOI: 10.1002/hep.20385] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Previous studies have demonstrated in hepatocytes that deoxycholic acid (DCA) promotes inactivation of protein tyrosine phosphatases (PTPases) and activation of ERBB1 and the extracellular-regulated kinase (ERK) 1/2 pathway. The present studies have determined the biochemical mechanism(s) through which these events occur. DCA and taurodeoxycholic acid (TDCA) (100 micromol/L) caused activation of ERBB1, insulin receptor, and the ERK1/2 and AKT pathways in primary rodent hepatocytes. DCA- and TDCA-induced receptor and signaling pathway activations were blocked by the reactive oxygen species (ROS) scavengers N-acetyl cysteine (NAC) and Trolox (TX), as well as by cyclosporin A (CsA) and bongkrekic acid (BKA). DCA activated the ERK1/2 pathway in HuH7 human hepatoma cells that was blocked by the incubation of cells with an ERBB1 inhibitor, NAC, TX, CsA, or BKA. DCA did not activate the ERK1/2 pathway in mitochondria-defective HuH7 Rho 0 cells. In HuH7 cells and primary hepatocytes, DCA enhanced the production of ROS, an effect that was abolished in Rho 0 cells and by prior incubation of cells with CsA or BKA. In hepatocytes and HuH7 cells, DCA inhibited PTPase activity. Incubation of hepatocytes with either CsA or BKA prevented DCA-induced inhibition of PTPase activity. Loss of mitochondrial function in Rho 0 cells also abolished the inhibitory effects of DCA on PTPase activity. In conclusion, DCA and TDCA cause ROS generation in hepatocytes that is dependent on metabolically active mitochondria. The generation of ROS is essential for PTPase inactivation, receptor tyrosine kinase activation, and enhanced signaling down the ERK1/2 and AKT pathways.
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Affiliation(s)
- Youwen Fang
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298-0058, USA
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