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Krylov D, Rodimova S, Karabut M, Kuznetsova D. Experimental Models for Studying Structural and Functional State of the Pathological Liver (Review). Sovrem Tekhnologii Med 2023; 15:65-82. [PMID: 38434194 PMCID: PMC10902899 DOI: 10.17691/stm2023.15.4.06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Indexed: 03/05/2024] Open
Abstract
Liver pathologies remain one of the leading causes of mortality worldwide. Despite a high prevalence of liver diseases, the possibilities of diagnosing, prognosing, and treating non-alcoholic and alcoholic liver diseases still have a number of limitations and require the development of new methods and approaches. In laboratory studies, various models are used to reconstitute the pathological conditions of the liver, including cell cultures, spheroids, organoids, microfluidic systems, tissue slices. We reviewed the most commonly used in vivo, in vitro, and ex vivo models for studying non-alcoholic fatty liver disease and alcoholic liver disease, toxic liver injury, and fibrosis, described their advantages, limitations, and prospects for use. Great emphasis was placed on the mechanisms of development of pathological conditions in each model, as well as the assessment of the possibility of reconstructing various key aspects of pathogenesis for all these pathologies. There is currently no consensus on the choice of the most adequate model for studying liver pathology. The choice of a certain effective research model is determined by the specific purpose and objectives of the experiment.
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Affiliation(s)
- D.P. Krylov
- Laboratory Assistant, Scientific Laboratory of Molecular Biotechnologies, Research Institute of Experimental Oncology and Biomedical Technologies; Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Square, Nizhny Novgorod, 603005, Russia; Student, Institute of Biology and Biomedicine; National Research Lobachevsky State University of Nizhny Novgorod, 23 Prospekt Gagarina, Nizhny Novgorod, 603022, Russia
| | - S.A. Rodimova
- Junior Researcher, Laboratory of Regenerative Medicine, Scientific Laboratory of Molecular Biotechnologies, Research Institute of Experimental Oncology and Biomedical Technologies; Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Square, Nizhny Novgorod, 603005, Russia
| | - M.M. Karabut
- Researcher, Laboratory of Genomics of Adaptive Antitumor Immunity, Research Institute of Experimental Oncology and Biomedical Technologies; Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Square, Nizhny Novgorod, 603005, Russia
| | - D.S. Kuznetsova
- Head of Laboratory of Molecular Biotechnologies, Research Institute of Experimental Oncology and Biomedical Technologies; Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Square, Nizhny Novgorod, 603005, Russia; Head of the Research Laboratory for Molecular Genetic Researches, Institute of Clinical Medicine; National Research Lobachevsky State University of Nizhny Novgorod, 23 Prospekt Gagarina, Nizhny Novgorod, 603022, Russia
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Adhikari R, Mitra R, Bennett RG, McVicker BL, Tuma PL. Alcohol-induced tubulin post-translational modifications directly alter hepatic protein trafficking. Hepatol Commun 2023; 7:02009842-202304010-00020. [PMID: 36972397 PMCID: PMC10043593 DOI: 10.1097/hc9.0000000000000103] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 02/03/2023] [Indexed: 03/29/2023] Open
Abstract
BACKGROUND Chronic ethanol exposure leads to enhanced protein acetylation and acetaldehyde adduction. Of the multitude of proteins that are modified on ethanol administration, tubulin is among the best studied. However, an open question is whether these modifications are observed in patient samples. Both modifications have also been implicated in promoting alcohol-induced defects in protein trafficking, but whether they do so directly is also unanswered. METHODS AND RESULTS We first confirmed that tubulin was hyperacetylated and acetaldehyde-adducted in the livers from ethanol-exposed individuals to a similar extent as observed in the livers from ethanol-fed animals and hepatic cells. Livers from individuals with nonalcohol-associated fatty liver showed modest increases in tubulin acetylation, whereas nonalcohol-associated fibrotic human and mouse livers showed virtually no tubulin modifications. We also asked whether tubulin acetylation or acetaldehyde adduction can directly explain the known alcohol-induced defects in protein trafficking. Acetylation was induced by overexpressing the α-tubulin-specific acetyltransferase, αTAT1, whereas adduction was induced by directly adding acetaldehyde to cells. Both αTAT1 overexpression and acetaldehyde treatment significantly impaired plus-end (secretion) and minus-end (transcytosis)-directed microtubule-dependent trafficking and clathrin-mediated endocytosis. Each modification led to similar levels of impairment as observed in ethanol-treated cells. The levels of impairment by either modification showed no dose dependence or no additive effects suggesting that substoichiometric tubulin modifications lead to altered protein trafficking and that lysines are not selectively modified. CONCLUSIONS These results not only confirm that enhanced tubulin acetylation is observed in human livers but that it is most relevant to alcohol-induced injury. Because these tubulin modifications are associated with altered protein trafficking that alters proper hepatic function, we propose that changing the cellular acetylation levels or scavenging free aldehydes are feasible strategies for treating alcohol-associated liver disease.
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Affiliation(s)
- Raghabendra Adhikari
- Department of Biology, The Catholic University of America, Washington, District of Columbia, USA
| | - Ramyajit Mitra
- Department of Biology, The Catholic University of America, Washington, District of Columbia, USA
| | - Robert G Bennett
- Research Service, VA Nebraska-Western Iowa Health Care System, Omaha, Nebraska, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Benita L McVicker
- Research Service, VA Nebraska-Western Iowa Health Care System, Omaha, Nebraska, USA
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Pamela L Tuma
- Department of Biology, The Catholic University of America, Washington, District of Columbia, USA
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Neuman MG, Seitz HK, Tuma PL, Osna NA, Casey CA, Kharbanda KK, Cohen LB, Malnick SDH, Adhikari R, Mitra R, Dagur RS, Ganesan M, Srinivas C, Madan Kumar A, New-Aaron M, Poluektova L, Thomes PG, Rasineni K, Opris M, Teschke R. Alcohol: basic and translational research; 15th annual Charles Lieber &1st Samuel French satellite symposium. Exp Mol Pathol 2022; 126:104750. [PMID: 35192844 PMCID: PMC9167794 DOI: 10.1016/j.yexmp.2022.104750] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 12/28/2021] [Accepted: 01/24/2022] [Indexed: 02/05/2023]
Abstract
The present review is based on the research presented at the symposium dedicated to the legacy of the two scientists that made important discoveries in the field of alcohol-induced liver damage: Professors C.S. Lieber and S.W. French. The invited speakers described pharmacological, toxicological and patho-physiological effects of alcohol misuse. Moreover, genetic biomarkers determining adverse drug reactions due to interactions between therapeutics used for chronic or infectious diseases and alcohol exposure were discussed. The researchers presented their work in areas of alcohol-induced impairment in lipid protein trafficking and endocytosis, as well as the role of lipids in the development of fatty liver. The researchers showed that alcohol leads to covalent modifications that promote hepatic dysfunction and injury. We concluded that using new advanced techniques and research ideas leads to important discoveries in science.
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Affiliation(s)
- Manuela G Neuman
- In Vitro Drug Safety and Biotechnology, Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada.
| | - Helmut K Seitz
- Centre of Liver and Alcohol Diseases, Ethianum Clinic, University of Heidelberg, Germany
| | - Pamela L Tuma
- The Catholic University of America, Department of Biology, Washington, DC 20064, USA
| | - Natalia A Osna
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Carol A Casey
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Kusum K Kharbanda
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Lawrence B Cohen
- Division of Gastroenterology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada
| | - Steve D H Malnick
- Department of Internal Medicine C, Kaplan Medical Center, Affiliated Hebrew University, Jerusalem, Israel
| | - Raghabendra Adhikari
- The Catholic University of America, Department of Biology, Washington, DC 20064, USA
| | - Ramyajit Mitra
- The Catholic University of America, Department of Biology, Washington, DC 20064, USA
| | - Raghubendra Singh Dagur
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Murali Ganesan
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Chava Srinivas
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Arumugam Madan Kumar
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Moses New-Aaron
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Larisa Poluektova
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Paul G Thomes
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Karuna Rasineni
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Mihai Opris
- In Vitro Drug Safety and Biotechnology, Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada; Family Medicine Clinic CAR, Bucharest, Romania
| | - Rolf Teschke
- Department of Internal Medicine II, Division of Gastroenterology and Hepatology, Klinikum Hanau, Hanau, Academic Teaching Hospital of the Medical Faculty, Goethe University Frankfurt/ Main, Frankfurt/Main, Germany
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Yeşiltepe O, Güler Çelik E, Geyik C, Gümüş ZP, Odaci Demirkol D, Coşkunol H, Timur S. Preparation of glutathione loaded nanoemulsions and testing of hepatoprotective activity on THLE-2 cells. Turk J Chem 2021; 45:436-451. [PMID: 34104055 PMCID: PMC8164205 DOI: 10.3906/kim-2007-54] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 01/06/2021] [Indexed: 12/29/2022] Open
Abstract
To improve bioavailability and stability of hydrophobic and hydrophilic compounds, nanoemulsions are good alternatives as delivery systems because of their nontoxic and nonirritant nature. Glutathione (GSH) suffers from low stability in water, where its encapsulation in nanoemulsions is a powerful strategy to its stability in aqueous systems. The aim of this study was to obtain nanoemulsions from the hydrophobic/hydrophilic contents of N. sativa seed oil so as to improve GSH stability along with bioavailability of N. sativa seed oil. Then, the prepared nanoemulsions were tested for in vitro hepatoprotective activity against ethanol toxicity. To the best of our knowledge, there is no study on the test of nanoemulsions by the combination of Nigella sativa seed oils and GSH in hepatoprotective activity. Here, nanoemulsions with different contents were prepared using Nigella sativa seed oils. Content analyses and characterisation studies of prepared nanoemulsions were carried out. In order to investigate the protective effects against to ethanol exposure, THLE-2 cells were pretreated with nanoemulsions for 2 h with the maximum benign dose (0.5 mg/mL of nanoemulsions). Ethanol (400 mM) was introduced to pretreated cells and nontreated cells for 48- or 72-h periods, followed by cell viability assay was carried out. Fluorescence microscopy tests revealed the introduction of the nanoemulsions into THLE-2 cells. The findings show that nanoformulations have promising in vitro hepatoprotective effects on the THLE-2 cell line against ethanol exposure.
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Affiliation(s)
- Ozan Yeşiltepe
- Institute on Drug Abuse Toxicology and Pharmaceutical Science, Ege University, İzmir Turkey
| | - Emine Güler Çelik
- Department of Biochemistry, Faculty of Science, Ege University, İzmir Turkey
| | - Caner Geyik
- Institute on Drug Abuse Toxicology and Pharmaceutical Science, Ege University, İzmir Turkey.,Department of Medical Biochemistry, Faculty of Medicine, İstinye University, İstanbul Turkey
| | - Zinar Pınar Gümüş
- Institute on Drug Abuse Toxicology and Pharmaceutical Science, Ege University, İzmir Turkey.,Central Research Testing and Analysis Laboratory Research and Application Center, Ege University, İzmir Turkey
| | | | - Hakan Coşkunol
- Department of Psychiatry, Faculty of Medicine, Ege University, İzmir Turkey
| | - Suna Timur
- Department of Biochemistry, Faculty of Science, Ege University, İzmir Turkey.,Central Research Testing and Analysis Laboratory Research and Application Center, Ege University, İzmir Turkey
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Neuman MG, Seitz HK, French SW, Malnick S, Tsukamoto H, Cohen LB, Hoffman P, Tabakoff B, Fasullo M, Nagy LE, Tuma PL, Schnabl B, Mueller S, Groebner JL, Barbara FA, Yue J, Nikko A, Alejandro M, Brittany T, Edward V, Harrall K, Saba L, Mihai O. Alcoholic-Hepatitis, Links to Brain and Microbiome: Mechanisms, Clinical and Experimental Research. Biomedicines 2020; 8:E63. [PMID: 32197424 PMCID: PMC7148515 DOI: 10.3390/biomedicines8030063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/02/2020] [Accepted: 03/09/2020] [Indexed: 02/07/2023] Open
Abstract
The following review article presents clinical and experimental features of alcohol-induced liver disease (ALD). Basic aspects of alcohol metabolism leading to the development of liver hepatotoxicity are discussed. ALD includes fatty liver, acute alcoholic hepatitis with or without liver failure, alcoholic steatohepatitis (ASH) leading to fibrosis and cirrhosis, and hepatocellular cancer (HCC). ALD is fully attributable to alcohol consumption. However, only 10-20% of heavy drinkers (persons consuming more than 40 g of ethanol/day) develop clinical ALD. Moreover, there is a link between behaviour and environmental factors that determine the amount of alcohol misuse and their liver disease. The range of clinical presentation varies from reversible alcoholic hepatic steatosis to cirrhosis, hepatic failure, and hepatocellular carcinoma. We aimed to (1) describe the clinico-pathology of ALD, (2) examine the role of immune responses in the development of alcoholic hepatitis (ASH), (3) propose diagnostic markers of ASH, (4) analyze the experimental models of ALD, (5) study the role of alcohol in changing the microbiota, and (6) articulate how findings in the liver and/or intestine influence the brain (and/or vice versa) on ASH; (7) identify pathways in alcohol-induced organ damage and (8) to target new innovative experimental concepts modeling the experimental approaches. The present review includes evidence recognizing the key toxic role of alcohol in ALD severity. Cytochrome p450 CYP2E1 activation may change the severity of ASH. The microbiota is a key element in immune responses, being an inducer of proinflammatory T helper 17 cells and regulatory T cells in the intestine. Alcohol consumption changes the intestinal microbiota and influences liver steatosis and liver inflammation. Knowing how to exploit the microbiome to modulate the immune system might lead to a new form of personalized medicine in ALF and ASH.
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Affiliation(s)
- Manuela G. Neuman
- In Vitro Drug Safety and Biotechnology, Toronto, ON M5G 1L5, Canada;
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON M5G 1L5, Canada
| | - Helmut Karl Seitz
- Department of Medicine, Centre of Alcohol Research, University of Heidelberg, Salem Medical Centre, 337374 Heidelberg, Germany; (H.K.S.); (S.M.)
| | - Samuel W. French
- Department of Pathology, Harbor-UCLA Medical Center and Los Angeles BioMedical Institute, Torrance, CA Harbor-UCLA Medical Center, Torrance, CA 90509, USA; (S.W.F.); (F.A.B.); (J.Y.); (A.N.); (M.A.); (T.B.); (V.E.)
| | - Stephen Malnick
- Department Internal Medicine C, Kaplan Medical Centre and Hebrew University of Jerusalem, Rehovot 76100, Israel;
| | - Heidekazu Tsukamoto
- Southern California Research Center for ALPD and Cirrhosis, Department of Pathology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90089-5311, USA;
- Department of Veterans; Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | - Lawrence B. Cohen
- Division of Gastroenterology, Sunnybrook Health Sciences Centre, Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON M4N 3M5, Canada;
| | - Paula Hoffman
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045-0511, USA; (P.H.); (B.T.); (K.H.); (L.S.)
| | - Boris Tabakoff
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045-0511, USA; (P.H.); (B.T.); (K.H.); (L.S.)
| | - Michael Fasullo
- College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, NY 12205, USA;
| | - Laura E. Nagy
- Departments of Pathobiology and Gastroenterology, Center for Liver Disease Research, Cleveland Clinic Foundation, Cleveland, OH 44195, USA;
| | - Pamela L. Tuma
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA; (P.L.T.); (J.L.G.)
| | - Bernd Schnabl
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA;
| | - Sebastian Mueller
- Department of Medicine, Centre of Alcohol Research, University of Heidelberg, Salem Medical Centre, 337374 Heidelberg, Germany; (H.K.S.); (S.M.)
| | - Jennifer L. Groebner
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA; (P.L.T.); (J.L.G.)
| | - French A. Barbara
- Department of Pathology, Harbor-UCLA Medical Center and Los Angeles BioMedical Institute, Torrance, CA Harbor-UCLA Medical Center, Torrance, CA 90509, USA; (S.W.F.); (F.A.B.); (J.Y.); (A.N.); (M.A.); (T.B.); (V.E.)
| | - Jia Yue
- Department of Pathology, Harbor-UCLA Medical Center and Los Angeles BioMedical Institute, Torrance, CA Harbor-UCLA Medical Center, Torrance, CA 90509, USA; (S.W.F.); (F.A.B.); (J.Y.); (A.N.); (M.A.); (T.B.); (V.E.)
| | - Afifiyan Nikko
- Department of Pathology, Harbor-UCLA Medical Center and Los Angeles BioMedical Institute, Torrance, CA Harbor-UCLA Medical Center, Torrance, CA 90509, USA; (S.W.F.); (F.A.B.); (J.Y.); (A.N.); (M.A.); (T.B.); (V.E.)
| | - Mendoza Alejandro
- Department of Pathology, Harbor-UCLA Medical Center and Los Angeles BioMedical Institute, Torrance, CA Harbor-UCLA Medical Center, Torrance, CA 90509, USA; (S.W.F.); (F.A.B.); (J.Y.); (A.N.); (M.A.); (T.B.); (V.E.)
| | - Tillman Brittany
- Department of Pathology, Harbor-UCLA Medical Center and Los Angeles BioMedical Institute, Torrance, CA Harbor-UCLA Medical Center, Torrance, CA 90509, USA; (S.W.F.); (F.A.B.); (J.Y.); (A.N.); (M.A.); (T.B.); (V.E.)
| | - Vitocruz Edward
- Department of Pathology, Harbor-UCLA Medical Center and Los Angeles BioMedical Institute, Torrance, CA Harbor-UCLA Medical Center, Torrance, CA 90509, USA; (S.W.F.); (F.A.B.); (J.Y.); (A.N.); (M.A.); (T.B.); (V.E.)
| | - Kylie Harrall
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045-0511, USA; (P.H.); (B.T.); (K.H.); (L.S.)
| | - Laura Saba
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045-0511, USA; (P.H.); (B.T.); (K.H.); (L.S.)
| | - Opris Mihai
- In Vitro Drug Safety and Biotechnology, Toronto, ON M5G 1L5, Canada;
- Department Family Medicine Clinic CAR, 010164 Bucharest, Romania
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Groebner JL, Girón-Bravo MT, Rothberg ML, Adhikari R, Tuma DJ, Tuma PL. Alcohol-induced microtubule acetylation leads to the accumulation of large, immobile lipid droplets. Am J Physiol Gastrointest Liver Physiol 2019; 317:G373-G386. [PMID: 31373507 PMCID: PMC6842993 DOI: 10.1152/ajpgi.00026.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Although steatosis (fatty liver) is a clinically well-described early stage of alcoholic liver disease, surprisingly little is known about how it promotes hepatotoxicity. We have shown that ethanol consumption leads to microtubule hyperacetylation that can explain ethanol-induced defects in protein trafficking. Because almost all steps of the lipid droplet life cycle are microtubule dependent and because microtubule acetylation promotes adipogenesis, we examined droplet dynamics in ethanol-treated cells. In WIF-B cells treated with ethanol and/or oleic acid (a fatty acid associated with the "Western" diet), we found that ethanol dramatically increased lipid droplet numbers and led to the formation of large, peripherally located droplets. Enhanced droplet formation required alcohol dehydrogenase-mediated ethanol metabolism, and peripheral droplet distributions required intact microtubules. We also determined that ethanol-induced microtubule acetylation led to impaired droplet degradation. Live-cell imaging revealed that droplet motility was microtubule dependent and that droplets were virtually stationary in ethanol-treated cells. To determine more directly whether microtubule hyperacetylation could explain impaired droplet motility, we overexpressed the tubulin-specific acetyltransferase αTAT1 to promote microtubule acetylation in the absence of alcohol. Droplet motility was impaired in αTAT1-expressing cells but to a lesser extent than in ethanol-treated cells. However, in both cases, the large immotile droplets (but not small motile ones) colocalized with dynein and dynactin (but not kinesin), implying that altered droplet-motor microtubule interactions may explain altered dynamics. These studies further suggest that modulating cellular acetylation is a potential strategy for treating alcoholic liver disease.NEW & NOTEWORTHY Chronic alcohol consumption with the "Western diet" enhances the development of fatty liver and leads to impaired droplet motility, which may have serious deletrious effects on hepatocyte function.
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Affiliation(s)
| | | | - Mia L. Rothberg
- 1Department of Biology, The Catholic University of America, Washington D. C.
| | | | - Dean J. Tuma
- 2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Pamela L. Tuma
- 1Department of Biology, The Catholic University of America, Washington D. C.
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Striz AC, Stephan AP, López-Coral A, Tuma PL. Rab17 regulates apical delivery of hepatic transcytotic vesicles. Mol Biol Cell 2018; 29:2887-2897. [PMID: 30256711 PMCID: PMC6249867 DOI: 10.1091/mbc.e18-07-0433] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A major focus for our laboratory is identifying the molecules and mechanisms that regulate basolateral-to-apical transcytosis in polarized hepatocytes. Our most recent studies have focused on characterizing the biochemical and functional properties of the small rab17 GTPase. We determined that rab17 is a monosumoylated protein and that this modification likely mediates selective interactions with the apically located syntaxin 2. Using polarized hepatic WIF-B cells exogenously expressing wild-type, dominant active/guanosine triphosphate (GTP)-bound, dominant negative/guanosine diphosphate (GDP)-bound, or sumoylation-deficient/K68R rab17 proteins, we confirmed that rab17 regulates basolateral-to-apical transcytotic vesicle docking and fusion with the apical surface. We further confirmed that transcytosis is impaired from the subapical compartment to the apical surface and that GTP-bound and sumoylated rab17 are likely required for apical vesicle docking. Because expression of the GTP-bound rab17 led to impaired transcytosis, whereas wild type had no effect, we further propose that rab17 GTP hydrolysis is required for vesicle delivery. We also determined that transcytosis of three classes of newly synthesized apical residents showed similar responses to rab17 mutant expression, indicating that rab17 is a general component of the transcytotic machinery required for apically destined vesicle docking and fusion.
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Affiliation(s)
- Anneliese C Striz
- Department of Biology, The Catholic University of America, Washington, DC 20064
| | - Anna P Stephan
- Department of Biology, The Catholic University of America, Washington, DC 20064
| | - Alfonso López-Coral
- Department of Biology, The Catholic University of America, Washington, DC 20064
| | - Pamela L Tuma
- Department of Biology, The Catholic University of America, Washington, DC 20064
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A Serine/Threonine Kinase 16-Based Phospho-Proteomics Screen Identifies WD Repeat Protein-1 As A Regulator Of Constitutive Secretion. Sci Rep 2018; 8:13049. [PMID: 30158666 PMCID: PMC6115458 DOI: 10.1038/s41598-018-31426-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 08/14/2018] [Indexed: 01/03/2023] Open
Abstract
The plasma membrane of polarized hepatocytes is functionally divided into two domains: the apical and basolateral. Our focus is to define the molecular basis of polarized protein sorting of newly-synthesized membrane and secretory proteins in WIF-B cells, an excellent model system for polarized hepatocytes. We determined that MAL2 (myelin and lymphocyte protein 2) and its binding partner, serine/threonine kinase 16 (STK16) regulate basolateral constitutive secretion. Because STK16 is a constitutively active kinase, we reasoned that constitutively phosphorylated substrates must participate in constitutive secretion. To identify either STK16 substrates or other proteins that regulate constitutive secretion, we took a proteomics approach. Post-nuclear supernatants from cells expressing wild type or a kinase-dead (E202A) STK16 were separated on 2D gels and immunoblotted with antibodies against phospho-serine/threonine residues. Sixteen spots were identified from E202A-expressing cells that reproducibly displayed decreased immunoreactivity. From these spots, 28 proteins were identified as possible STK16 substrates. Out of these 28 possible substrates, 25% of them encode predicted STK16 phosphorylation consensus sites, with WD repeat containing protein-1 (WDR1) encoding two such sites. Based on this finding and on the finding that actin remodeling is required for hepatic secretion, we further confirmed that WDR1 is a phosphoprotein that regulates secretion.
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Duryee MJ, Wiese BM, Bowman JR, Vanlandingham JD, Klassen LW, Thiele GE, Hunter CD, Anderson DR, Mikuls TR, Thiele GM. Liver tissue metabolically transformed by alcohol induces immune recognition of liver self-proteins but not in vivo inflammation. Am J Physiol Gastrointest Liver Physiol 2018; 314:G418-G430. [PMID: 29351393 PMCID: PMC5899239 DOI: 10.1152/ajpgi.00183.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Precision-cut liver slices (PCLSs) provide a novel model for studies of alcoholic liver disease (ALD). This is relevant, as in vivo ethanol exposure does not appear to generate significant liver damage in ethanol-fed mice, except in the National Institute on Alcohol Abuse and Alcoholism binge model of ALD. Previous studies have shown that the two metabolites of ethanol consumption, malondialdhyde (MDA) and acetaldehyde (AA), combine to form MDA-AA (MAA) adducts, which have been correlated with the development and progression of ALD. In this study, murine PCLSs were incubated with ethanol and examined for the production of MAA adducts. PCLSs were homogenized, and homogenates were injected into C57BL/6 mice. PCLSs from control-, pair-, and ethanol-fed animals served as targets in in situ cytotoxic assays using primed T cells from mice hyperimmunized with control or ethanol-exposed PCLS homogenates. A CD45.1/CD45.2 passive-transfer model was used to determine whether T cells from the spleens of mice hyperimmunized with PCLS ethanol-exposed homogenates trafficked to the liver. PCLSs incubated with ethanol generated MAA-modified proteins in situ. Cytotoxic (CD8+) T cells from immunized mice killed naïve PCLSs from control- and pair-fed mice in vitro, a response that was blunted in PCLSs from ethanol-fed mice. Furthermore, CD45.1 CD8+ T cells from hyperimmunized mice trafficked to the liver but did not initiate liver damage. This study demonstrates that exposure to liver tissue damaged by ethanol mediates robust immune responses to well-characterized alcohol metabolites and native liver proteins in vitro. Moreover, although these proinflammatory T cells traffic to the liver, these responses appear to be dampened in vivo by locally acting pathways. NEW & NOTEWORTHY This study shows that the metabolites of ethanol and lipid breakdown produce malondialdehyde-acetaldehyde adducts in the precision-cut liver slice model system. Additionally, precision-cut liver slices exposed to ethanol and harboring malondialdehyde-acetaldehyde adducts generate liver-specific antibody and T cell responses in the spleens of naïve mice that could traffic to the liver.
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Affiliation(s)
- Michael J. Duryee
- 1Experimental Immunology Laboratory, Division of Rheumatology and Immunology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska,2Experimental Immunology Laboratory, Omaha Veterans Affairs Medical Center, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Benjamin M. Wiese
- 1Experimental Immunology Laboratory, Division of Rheumatology and Immunology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Jordan R. Bowman
- 1Experimental Immunology Laboratory, Division of Rheumatology and Immunology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Jared D. Vanlandingham
- 1Experimental Immunology Laboratory, Division of Rheumatology and Immunology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Lynell W. Klassen
- 1Experimental Immunology Laboratory, Division of Rheumatology and Immunology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska,2Experimental Immunology Laboratory, Omaha Veterans Affairs Medical Center, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Geoffrey E. Thiele
- 1Experimental Immunology Laboratory, Division of Rheumatology and Immunology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Carlos D. Hunter
- 1Experimental Immunology Laboratory, Division of Rheumatology and Immunology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska,2Experimental Immunology Laboratory, Omaha Veterans Affairs Medical Center, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Daniel R. Anderson
- 3Experimental Immunology, Division of Cardiology, Department of Internal Medicine, Research in Cardiovascular Disease Laboratory at the University of Nebraska Medical Center, Omaha, Nebraska
| | - Ted R. Mikuls
- 1Experimental Immunology Laboratory, Division of Rheumatology and Immunology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska,2Experimental Immunology Laboratory, Omaha Veterans Affairs Medical Center, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Geoffrey M. Thiele
- 1Experimental Immunology Laboratory, Division of Rheumatology and Immunology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska,2Experimental Immunology Laboratory, Omaha Veterans Affairs Medical Center, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska,4Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska
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10
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Doody EE, Groebner JL, Walker JR, Frizol BM, Tuma DJ, Fernandez DJ, Tuma PL. Ethanol metabolism by alcohol dehydrogenase or cytochrome P 450 2E1 differentially impairs hepatic protein trafficking and growth hormone signaling. Am J Physiol Gastrointest Liver Physiol 2017; 313:G558-G569. [PMID: 28864499 PMCID: PMC5814672 DOI: 10.1152/ajpgi.00027.2017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 08/15/2017] [Accepted: 08/21/2017] [Indexed: 01/31/2023]
Abstract
The liver metabolizes alcohol using alcohol dehydrogenase (ADH) and cytochrome P450 2E1 (CYP2E1). Both enzymes metabolize ethanol into acetaldehyde, but CYP2E1 activity also results in the production of reactive oxygen species (ROS) that promote oxidative stress. We have previously shown that microtubules are hyperacetylated in ethanol-treated polarized, hepatic WIF-B cells and livers from ethanol-fed rats. We have also shown that enhanced protein acetylation correlates with impaired clathrin-mediated endocytosis, constitutive secretion, and nuclear translocation and that the defects are likely mediated by acetaldehyde. However, the roles of CYP2E1-generated metabolites and ROS in microtubule acetylation and these alcohol-induced impairments have not been examined. To determine if CYP2E1-mediated alcohol metabolism is required for enhanced acetylation and the trafficking defects, we coincubated cells with ethanol and diallyl sulfide (DAS; a CYP2E1 inhibitor) or N-acetyl cysteine (NAC; an antioxidant). Both agents failed to prevent microtubule hyperacetylation in ethanol-treated cells and also failed to prevent impaired secretion or clathrin-mediated endocytosis. Somewhat surprisingly, both DAS and NAC prevented impaired STAT5B nuclear translocation. Further examination of microtubule-independent steps of the pathway revealed that Jak2/STAT5B activation by growth hormone was prevented by DAS and NAC. These results were confirmed in ethanol-exposed HepG2 cells expressing only ADH or CYP2E1. Using quantitative RT-PCR, we further determined that ethanol exposure led to blunted growth hormone-mediated gene expression. In conclusion, we determined that alcohol-induced microtubule acetylation and associated defects in microtubule-dependent trafficking are mediated by ADH metabolism whereas impaired microtubule-independent Jak2/STAT5B activation is mediated by CYP2E1 activity.NEW & NOTEWORTHY Impaired growth hormone-mediated signaling is observed in ethanol-exposed hepatocytes and is explained by differential effects of alcohol dehydrogenase (ADH)- and cytochrome P450 2E1 (CYP2E1)-mediated ethanol metabolism on the Jak2/STAT5B pathway.
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Affiliation(s)
- Erin E. Doody
- 1Department of Biology, The Catholic University of America, Washington, District of Columbia;
| | - Jennifer L. Groebner
- 1Department of Biology, The Catholic University of America, Washington, District of Columbia;
| | - Jetta R. Walker
- 2Northern Virginia Community College, Alexandria, Virginia; and
| | - Brittnee M. Frizol
- 1Department of Biology, The Catholic University of America, Washington, District of Columbia;
| | - Dean J. Tuma
- 3Department of Internal Medicine, University of Nebraska, Omaha, Nebraska
| | | | - Pamela L. Tuma
- 1Department of Biology, The Catholic University of America, Washington, District of Columbia;
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11
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Groebner JL, Tuma PL. The Altered Hepatic Tubulin Code in Alcoholic Liver Disease. Biomolecules 2015; 5:2140-59. [PMID: 26393662 PMCID: PMC4598792 DOI: 10.3390/biom5032140] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 08/21/2015] [Accepted: 08/24/2015] [Indexed: 01/01/2023] Open
Abstract
The molecular mechanisms that lead to the progression of alcoholic liver disease have been actively examined for decades. Because the hepatic microtubule cytoskeleton supports innumerable cellular processes, it has been the focus of many such mechanistic studies. It has long been appreciated that α-tubulin is a major target for modification by highly reactive ethanol metabolites and reactive oxygen species. It is also now apparent that alcohol exposure induces post-translational modifications that are part of the natural repertoire, mainly acetylation. In this review, the modifications of the "tubulin code" are described as well as those adducts by ethanol metabolites. The potential cellular consequences of microtubule modification are described with a focus on alcohol-induced defects in protein trafficking and enhanced steatosis. Possible mechanisms that can explain hepatic dysfunction are described and how this relates to the onset of liver injury is discussed. Finally, we propose that agents that alter the cellular acetylation state may represent a novel therapeutic strategy for treating liver disease.
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Affiliation(s)
- Jennifer L Groebner
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA.
| | - Pamela L Tuma
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA.
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12
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Groebner JL, Fernandez DJ, Tuma DJ, Tuma PL. Alcohol-induced defects in hepatic transcytosis may be explained by impaired dynein function. Mol Cell Biochem 2014; 397:223-33. [PMID: 25148871 DOI: 10.1007/s11010-014-2190-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 08/13/2014] [Indexed: 01/10/2023]
Abstract
Alcoholic liver disease has been clinically well described, but the molecular mechanisms leading to hepatotoxicity have not been fully elucidated. Previously, we determined that microtubules are hyperacetylated and more stable in ethanol-treated WIF-B cells, VL-17A cells, liver slices, and in livers from ethanol-fed rats. From our recent studies, we believe that these modifications can explain alcohol-induced defects in microtubule motor-dependent protein trafficking including nuclear translocation of a subset of transcription factors. Since cytoplasmic dynein/dynactin is known to mediate both microtubule-dependent translocation and basolateral to apical/canalicular transcytosis, we predicted that transcytosis is impaired in ethanol-treated hepatic cells. We monitored transcytosis of three classes of newly synthesized canalicular proteins in polarized, hepatic WIF-B cells, an emerging model system for the study of liver disease. As predicted, canalicular delivery of all proteins tested was impaired in ethanol-treated cells. Unlike in control cells, transcytosing proteins were observed in discrete sub-canalicular puncta en route to the canalicular surface that aligned along acetylated microtubules. We further determined that the stalled transcytosing proteins colocalized with dynein/dynactin in treated cells. No changes in vesicle association were observed for either dynein or dynactin in ethanol-treated cells, but significantly enhanced dynein binding to microtubules was observed. From these results, we propose that enhanced dynein binding to microtubules in ethanol-treated cells leads to decreased motor processivity resulting in vesicle stalling and in impaired canalicular delivery. Our studies also importantly indicate that modulating cellular acetylation levels with clinically tolerated deacetylase agonists may be a novel therapeutic strategy for treating alcoholic liver disease.
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Affiliation(s)
- Jennifer L Groebner
- Department of Biology, The Catholic University of America, 620 Michigan Avenue, NE, Washington, DC, 20064, USA
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13
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Do THT, Gaboriau F, Cannie I, Batusanski F, Ropert M, Moirand R, Brissot P, Loreal O, Lescoat G. Iron-mediated effect of alcohol on hepatocyte differentiation in HepaRG cells. Chem Biol Interact 2013; 206:117-25. [PMID: 24025710 DOI: 10.1016/j.cbi.2013.08.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 08/19/2013] [Accepted: 08/30/2013] [Indexed: 01/16/2023]
Abstract
The development of alcoholic liver diseases depends on the ability of hepatocyte to proliferate and differentiate in the case of alcohol-induced injury. Our previous work showed an inhibitory effect of alcohol on hepatocyte proliferation. However, the effect of alcohol on hepatocyte differentiation has not yet been precisely characterized. In the present study, we evaluated the effect of alcohol on hepatocyte differentiation in relationship with changes of iron metabolism in HepaRG cells. This unique bipotent human cell line can differentiate into hepatocytes and biliary epithelial cells, paralleling liver development. Results showed that alcohol reduced cell viability, total protein level and enhanced hepatic enzymes leakage in differentiated HepaRG cells. Moreover, it caused cell enlargement, decreased number of hepatocyte and expression of C/EBPα as well as bile canaliculi F-actin. Alcohol increased expression of hepatic cell-specific markers and alcohol-metabolizing enzymes (ADH2, CYP2E1). This was associated with a lipid peroxidation and an iron excess expressed by an increase in total iron content, ferritin level, iron uptake as well as an overexpression of genes involved in iron transport and storage. Alcohol-induced hepatoxicity was amplified by exogenous iron via exceeding iron overload. Taken together, our data demonstrate that in differentiated hepatocytes, alcohol reduces proliferation while increasing expression of hepatic cell-specific markers. Moreover, iron overload could be one of the underlying mechanisms of effect of alcohol on the whole differentiation process of hepatocytes.
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Affiliation(s)
- Thi Hong Tuoi Do
- Inserm, UMR 991, «Foie, Métabolismes et Cancer», F-35033 Rennes, France; Université de Rennes 1, F-35043 Rennes, France; University of Medicine and Pharmacy at Ho Chi Minh City, Viet Nam.
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14
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Grosse B, Degrouard J, Jaillard D, Cassio D. Build them up and break them down: Tight junctions of cell lines expressing typical hepatocyte polarity with a varied repertoire of claudins. Tissue Barriers 2013; 1:e25210. [PMID: 24665408 PMCID: PMC3783225 DOI: 10.4161/tisb.25210] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Revised: 05/28/2013] [Accepted: 05/29/2013] [Indexed: 12/14/2022] Open
Abstract
Tight junctions (TJs) of cells expressing simple epithelial polarity have been extensively studied, but less is known about TJs of cells expressing complex polarity. In this paper we analyzed, TJs of four different lines, that form bile canaliculi (BC) and express typical hepatocyte polarity; WIF-B9, 11–3, Can 3–1, Can 10. Striking differences were observed in claudin expression. None of the cell lines produced claudin-1. WIF-B9 and 11–3 expressed only claudin-2 while Can 3–1 and Can 10 expressed claudin-2,-3,-4,-5. TJs of these two classes of lines differed in their ultra-stucture, paracellular permeability, and robustness. Lines expressing a large claudin repertoire, especially Can 10, had complex and efficient TJs, that were maintained when cells were depleted in calcium. Inversely, TJs of WIF-B9 and 11–3 were leaky, permissive and dismantled by calcium depletion. Interestingly, we found that during the polarization process, TJ proteins expressed by all lines were sequentially settled in a specific order: first occludin, ZO-1 and cingulin, then JAM-A and ZO-2, finally claudin-2. Claudins expressed only in Can lines were also sequentially settled: claudin-3 was the first settled. Inhibition of claudin-3 expression delayed BC formation in Can10 and induced the expression of simple epithelial polarity. These results highlight the role of claudins in the settlement and the efficiency of TJs in lines expressing typical hepatocyte polarity. Can 10 seems to be the most promising of these lines because of its claudin repertoire near that of hepatocytes and its capacity to form extended tubular BC sealed by efficient TJs.
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Affiliation(s)
- Brigitte Grosse
- Inserm, UMR-S 757; Orsay, France ; Université Paris-Sud; Orsay, France
| | | | | | - Doris Cassio
- Inserm, UMR-S 757; Orsay, France ; Université Paris-Sud; Orsay, France
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15
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CYP2E1-catalyzed alcohol metabolism: role of oxidant generation in interferon signaling, antigen presentation and autophagy. Subcell Biochem 2013; 67:177-97. [PMID: 23400922 DOI: 10.1007/978-94-007-5881-0_6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cytochrome P450 2E1 (CYP2E1) is one of two major enzymes that catalyze ethanol oxidation in the liver. CYP2E1 is also unique because it is inducible, as its hepatic content rises after continuous (chronic) ethanol administration, thereby accelerating the rate of ethanol metabolism and affording greater tolerance to heavy alcohol consumption. However, the broad substrate specificity of CYP2E1 and its capacity to generate free radicals from alcohol and other hepatotoxins, places CYP2E1 as a central focus of not only liver toxicity, but also as an enzyme that regulates cytokine signaling, antigen presentation, and macromolecular degradation, all of which are crucial to liver cell function and viability. Here, we describe our own and other published work relevant to the importance of CYP2E1-catalyzed ethanol oxidation and how this catalysis affects the aforementioned cellular processes to produce liver injury.
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16
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Fernandez DJ, Tuma DJ, Tuma PL. Hepatic microtubule acetylation and stability induced by chronic alcohol exposure impair nuclear translocation of STAT3 and STAT5B, but not Smad2/3. Am J Physiol Gastrointest Liver Physiol 2012; 303:G1402-15. [PMID: 23064763 PMCID: PMC3532545 DOI: 10.1152/ajpgi.00071.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Although alcoholic liver disease is clinically well described, the molecular basis for alcohol-induced hepatotoxicity is not well understood. Previously, we found that alcohol exposure led to increased microtubule acetylation and stability in polarized, hepatic WIF-B cells and in livers from ethanol-fed rats. Because microtubules are known to regulate transcription factor nuclear translocation and dynamic microtubules are required for translocation of at least a subset of these factors, we examined whether alcohol-induced microtubule acetylation and stability impair nuclear translocation. We examined nuclear delivery of factors representing the two mechanisms by which microtubules regulate translocation. To represent factors that undergo directed delivery, we examined growth hormone-induced STAT5B translocation and IL-6-induced STAT3 translocation. To represent factors that are sequestered in the cytoplasm by microtubule attachment until ligand activation, we examined transforming growth factor-β-induced Smad2/3 translocation. We found that ethanol exposure selectively impaired translocation of the STATs, but not Smad2/3. STAT5B delivery was decreased to a similar extent by addition of taxol (a microtubule-stabilizing drug) or trichostatin A (a deacetylase inhibitor), agents that promote microtubule acetylation in the absence of alcohol. Thus the alcohol-induced impairment of STAT nuclear translocation can be explained by increased microtubule acetylation and stability. Only ethanol treatment impaired STAT5B activation, indicating that microtubules are not important for its activation by Jak2. Furthermore, nuclear exit was not changed in treated cells, indicating that this process is also independent of microtubule acetylation and stability. Together, these results raise the exciting possibility that deacetylase agonists may be effective therapeutics for the treatment of alcoholic liver disease.
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Affiliation(s)
- David J. Fernandez
- 1Department of Biology, The Catholic University of America, Washington, DC; and
| | - Dean J. Tuma
- 2Department of Internal Medicine, University of Nebraska, Omaha, Nebraska
| | - Pamela L. Tuma
- 1Department of Biology, The Catholic University of America, Washington, DC; and
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17
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Shepard BD, Tuma DJ, Tuma PL. Lysine acetylation induced by chronic ethanol consumption impairs dynamin-mediated clathrin-coated vesicle release. Hepatology 2012; 55:1260-70. [PMID: 22095875 PMCID: PMC3292665 DOI: 10.1002/hep.24785] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 10/19/2011] [Indexed: 12/25/2022]
Abstract
UNLABELLED The liver is the major site of ethanol metabolism and thus sustains the most injury from chronic alcohol consumption. Ethanol metabolism by the hepatocyte leads to the generation of reactive metabolites and oxygen radicals that can readily adduct DNA, lipids, and proteins. More recently, it has become apparent that ethanol consumption also leads to increased post-translational modifications of the natural repertoire, including lysine hyperacetylation. Previously, we determined that alcohol consumption selectively impairs clathrin-mediated internalization in polarized hepatocytes. However, neither the step at which the block occurs nor the mechanism responsible for the defect have been identified. To identify the specific step at which clathrin-mediated internalization is impaired, we examined the distributions, levels, and assembly of selected components of the clathrin machinery in control and ethanol-treated cells. To determine whether the impairment is caused by ethanol-induced lysine acetylation, we also examined the same coat components in cells treated with trichostatin A (TSA), a deacetylase inhibitor that leads to protein hyperacetylation in the absence of ethanol. CONCLUSION We determined that both ethanol and TSA impair internalization at a late stage before vesicle fission. We further determined that this defect is likely the result of decreased dynamin recruitment to the necks of clathrin-coated invaginations resulting in impaired vesicle budding. These results also raise the exciting possibility that agents that promote lysine deacetylation may be effective therapeutics for the treatment of alcoholic liver disease.
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Affiliation(s)
- Blythe D. Shepard
- Department of Biology, The Catholic University of America, Washington DC 20064
| | - Dean J. Tuma
- Department of Internal Medicine, University of Nebraska, Omaha, NE 68105
| | - Pamela L. Tuma
- Department of Biology, The Catholic University of America, Washington DC 20064
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18
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Lipid droplet accumulation and impaired fat efflux in polarized hepatic cells: consequences of ethanol metabolism. Int J Hepatol 2012; 2012:978136. [PMID: 22506128 PMCID: PMC3312290 DOI: 10.1155/2012/978136] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 11/22/2011] [Accepted: 12/08/2011] [Indexed: 12/20/2022] Open
Abstract
Steatosis, an early manifestation in alcoholic liver disease, is associated with the accumulation of hepatocellular lipid droplets (LDs). However, the role ethanol metabolism has in LD formation and turnover remains undefined. Here, we assessed LD dynamics following ethanol and oleic acid treatment to ethanol-metabolizing WIF-B cells (a hybrid of human fibroblasts (WI 38) and Fao rat hepatoma cells). An OA dose-dependent increase in triglyceride and stained lipids was identified which doubled (P < 0.05) in the presence of ethanol. This effect was blunted with the inclusion of an alcohol metabolism inhibitor. The ethanol/ OA combination also induced adipophilin, LD coat protein involved in the attenuation of lipolysis. Additionally, ethanol treatment resulted in a significant reduction in lipid efflux. These data demonstrate that the metabolism of ethanol in hepatic cells is related to LD accumulation, impaired fat efflux, and enhancements in LD-associated proteins. These alterations in LD dynamics may contribute to ethanol-mediated defects in hepatocellular LD regulation and the formation of steatosis.
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19
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Schaffert CS, Duryee MJ, Bennett RG, DeVeney AL, Tuma DJ, Olinga P, Easterling KC, Thiele GM, Klassen LW. Exposure of precision-cut rat liver slices to ethanol accelerates fibrogenesis. Am J Physiol Gastrointest Liver Physiol 2010; 299:G661-8. [PMID: 20595623 PMCID: PMC2950678 DOI: 10.1152/ajpgi.00287.2009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Ethanol metabolism in the liver induces oxidative stress and altered cytokine production preceding myofibroblast activation and fibrogenic responses. The purpose of this study was to determine how ethanol affects the fibrogenic response in precision-cut liver slices (PCLS). PCLS were obtained from chow-fed male Wistar rats (200-300 g) and were cultured up to 96 h in medium, 25 mM ethanol, or 25 mM ethanol and 0.5 mM 4-methylpyrazole (4-MP), an inhibitor of ethanol metabolism. Slices from every time point (24, 48, 72, and 96 h) were examined for glutathione (GSH) levels, lipid peroxidation [thiobarbituric acid-reactive substance (TBARS) assay], cytokine production (ELISA and RT-PCR), and myofibroblast activation [immunoblotting and immunohistochemistry for smooth muscle actin (SMA) and collagen]. Treatment of PCLS with 25 mM ethanol induced significant oxidative stress within 24 h, including depletion of cellular GSH and increased lipid peroxidation compared with controls (P < 0.05). Ethanol treatment also elicited a significant and sustained increase in interleukin-6 (IL-6) production (P < 0.05). Importantly, ethanol treatment accelerates a fibrogenic response after 48 h, represented by significant increases in SMA and collagen 1alpha(I) production (P < 0.05). These ethanol-induced effects were prevented by the addition of 4-MP. Ethanol metabolism induces oxidative stress (GSH depletion and increased lipid peroxidation) and sustained IL-6 expression in rat PCLS. These phenomena precede and coincide with myofibroblast activation, which occurs within 48 h of treatment. These results indicate the PCLS can be used as in vitro model for studying multicellular interactions during the early stages of ethanol-induced liver injury and fibrogenesis.
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Affiliation(s)
- Courtney S. Schaffert
- 1Research, Veterans Affairs Medical Center and the Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Michael J. Duryee
- 1Research, Veterans Affairs Medical Center and the Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Robert G. Bennett
- 1Research, Veterans Affairs Medical Center and the Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Amy L. DeVeney
- 1Research, Veterans Affairs Medical Center and the Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Dean J. Tuma
- 1Research, Veterans Affairs Medical Center and the Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Peter Olinga
- 2University of Groningen, GUIDE, Department of Pharmacokinetics & Drug Delivery, Groningen, The Netherlands
| | - Karen C. Easterling
- 1Research, Veterans Affairs Medical Center and the Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Geoffrey M. Thiele
- 1Research, Veterans Affairs Medical Center and the Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Lynell W. Klassen
- 1Research, Veterans Affairs Medical Center and the Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska; and
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McVicker BL, Tuma PL, Kharbanda KK, Lee SML, Tuma DJ. Relationship between oxidative stress and hepatic glutathione levels in ethanol-mediated apoptosis of polarized hepatic cells. World J Gastroenterol 2009; 15:2609-16. [PMID: 19496190 PMCID: PMC2691491 DOI: 10.3748/wjg.15.2609] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [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
AIM: To investigate the role of reactive oxygen species (ROS) in ethanol-mediated cell death of polarized hepatic (WIF-B) cells.
METHODS: In this work, WIF-B cultures were treated with pyrazole (inducer of cytochrome P4502E1, CYP2E1) and/or L-buthionine sulfoximine (BSO), a known inhibitor of hepatic glutathione (GSH), followed by evaluation of ROS production, antioxidant levels, and measures of cell injury (apoptosis and necrosis).
RESULTS: The results revealed that ethanol treatment alone caused a significant two-fold increase in the activation of caspase-3 as well as a similar doubling in ROS. When the activity of the CYP2E1 was increased by pyrazole pretreatment, an additional two-fold elevation in ROS was detected. However, the CYP2E1-related ROS elevation was not accompanied with a correlative increase in apoptotic cell injury, but rather was found to be associated with an increase in necrotic cell death. Interestingly, when the thiol status of the cells was manipulated using BSO, the ethanol-induced activation of caspase-3 was abrogated. Additionally, ethanol-treated cells displayed enhanced susceptibility to Fas-mediated apoptosis that was blocked by GSH depletion as a result of diminished caspase-8 activity.
CONCLUSION: Apoptotic cell death induced as a consequence of ethanol metabolism is not completely dependent upon ROS status but is dependent on sustained GSH levels.
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Fernandez DJ, McVicker BL, Tuma DJ, Tuma PL. Ethanol selectively impairs clathrin-mediated internalization in polarized hepatic cells. Biochem Pharmacol 2009; 78:648-55. [PMID: 19463792 DOI: 10.1016/j.bcp.2009.05.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 05/08/2009] [Accepted: 05/11/2009] [Indexed: 11/26/2022]
Abstract
Although alcoholic liver disease is clinically well-described, the molecular basis for alcohol-induced hepatotoxicity is not well understood. Previously, we determined that the clathrin-mediated internalization of asialoglycoprotein receptor was impaired in ethanol-treated WIF-B cells whereas the internalization of a glycophosphatidylinositol-anchored protein thought to be endocytosed via a caveolae/raft-mediated pathway was not changed suggesting that clathrin-mediated endocytosis is selectively impaired by ethanol. To test this possibility, we examined the internalization of a panel of proteins and compounds internalized by different mechanisms in control and ethanol-treated WIF-B cells. We determined that the internalization of markers known to be internalized via clathrin-mediated mechanisms was impaired. In contrast, the internalization of markers for caveolae/raft-mediated endocytosis, fluid phase internalization or non-vesicle-mediated uptake was not impaired in ethanol-treated cells. We further determined that clathrin heavy chain accumulated at the basolateral surface in small puncta in ethanol-treated cells while there was decreased dynamin-2 membrane association. Interestingly, the internalization of resident apical proteins that lack any known internalization signals was also disrupted by ethanol suggesting that these proteins are internalized via clathrin-mediated mechanisms. This conclusion is consistent with our findings that dominant negative dynamin-2 overexpression impaired internalization of known clathrin markers and single spanning apical residents, but not of markers of fluid phase or raft-mediated internalization. Together these results indicate that ethanol exposure selectively impairs hepatic clathrin-mediated internalization by preventing vesicle fission from the plasma membrane.
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Affiliation(s)
- David J Fernandez
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
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22
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Shepard BD, Joseph RA, Kannarkat GT, Rutledge TM, Tuma DJ, Tuma PL. Alcohol-induced alterations in hepatic microtubule dynamics can be explained by impaired histone deacetylase 6 function. Hepatology 2008; 48:1671-9. [PMID: 18697214 PMCID: PMC2965519 DOI: 10.1002/hep.22481] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
UNLABELLED We have been using polarized, hepatic WIF-B cells to examine ethanol-induced liver injury. These cells polarize in culture and maintain numerous liver-specific activities including the ability to metabolize alcohol. Previously, we found that microtubules were more highly acetylated and more stable in ethanol-treated WIF-B cells and that increased microtubule acetylation required ethanol metabolism and was likely mediated by acetaldehyde. This study was aimed at identifying the mechanism responsible for increased microtubule acetylation. We examined the expression of two known microtubule deacetylases, histone deacetylase 6 (HDAC6) and Sirtuin T2 (SirT2), in WIF-B cells. Immunoblotting, immunofluorescence microscopy, and assays using the SirT2 inhibitor nicotinamide revealed that WIF-B cells do not express SirT2. In contrast, HDAC6 was highly expressed in WIF-B cells. Addition of trichostatin A (TSA), an HDAC6 inhibitor, induced microtubule acetylation to the same extent as in ethanol-treated cells (approximately threefold). Although immunofluorescence labeling revealed that HDAC6 distribution did not change in ethanol-treated cells, immunoblotting showed HDAC6 protein levels slightly decreased. HDAC6 solubility was increased in nocodazole-treated cells, suggesting impaired microtubule binding. Direct microtubule binding assays confirmed this hypothesis. The decreased microtubule binding was partially prevented by 4-methyl pyrazole, indicating the effect was in part mediated by acetaldehyde. Interestingly, HDAC6 from ethanol-treated cells was able to bind and deacetylate exogenous tubulin to the same extent as control, suggesting that ethanol-induced tubulin modifications prevented HDAC6 binding to endogenous microtubules. CONCLUSION We propose that lower HDAC6 levels combined with decreased microtubule binding lead to increased tubulin acetylation in ethanol-treated cells.
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Affiliation(s)
- Blythe D. Shepard
- Department of Biology, The Catholic University of America, Washington, DC
| | - Rohan A. Joseph
- Department of Biology, The Catholic University of America, Washington, DC
| | | | | | - Dean J. Tuma
- Department of Internal Medicine, University of Nebraska, Omaha, NE
| | - Pamela L. Tuma
- Department of Biology, The Catholic University of America, Washington, DC
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Klassen LW, Thiele GM, Duryee MJ, Schaffert CS, DeVeney AL, Hunter CD, Olinga P, Tuma DJ. An in vitro method of alcoholic liver injury using precision-cut liver slices from rats. Biochem Pharmacol 2008; 76:426-36. [PMID: 18599023 DOI: 10.1016/j.bcp.2008.05.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Revised: 05/07/2008] [Accepted: 05/08/2008] [Indexed: 12/24/2022]
Abstract
Alcohol abuse results in liver injury, but investigations into the mechanism(s) for this injury have been hampered by the lack of appropriate in vitro culture models in which to conduct in depth and specific studies. In order to overcome these shortcomings, we have developed the use of precision-cut liver slices (PCLS) as an in vitro culture model in which to investigate how ethanol causes alcohol-induced liver injury. In these studies, it was shown that the PCLS retained excellent viability as determined by lactate dehydrogenase and adenosine triphosphate (ATP) levels over a 96-h period of incubation. More importantly, the major enzymes of ethanol detoxification; alcohol dehydrogenase, aldehyde dehydrogenase, and cytochrome P4502E1, remained active and PCLS readily metabolized ethanol and produced acetaldehyde. Within 24 h and continuing up to 96h the PCLS developed fatty livers and demonstrated an increase in the redox state. These PCLS secreted albumin, and albumin secretion was decreased by ethanol treatment. All of these impairments were reversed following the addition of 4-methylpyrazole, which is an inhibitor of ethanol metabolism. Therefore, this model system appears to mimic the ethanol-induced changes in the liver that have been previously reported in human and animal studies, and may be a useful model for the study of alcoholic liver disease.
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Affiliation(s)
- Lynell W Klassen
- Experimental Immunology Laboratory, University of Nebraska Medical Center, Department of Internal Medicine, Section of Rheumatology, 983025 Nebraska Medical Center, Omaha, NE 68198-3025, USA
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24
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Joseph RA, Shepard BD, Kannarkat GT, Rutledge TM, Tuma DJ, Tuma PL. Microtubule acetylation and stability may explain alcohol-induced alterations in hepatic protein trafficking. Hepatology 2008; 47:1745-53. [PMID: 18161881 PMCID: PMC2957806 DOI: 10.1002/hep.22014] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
UNLABELLED We have been using polarized hepatic WIF-B cells to examine ethanol-induced liver injury. Previously, we determined microtubules were more highly acetylated and more stable in ethanol-treated WIF-B cells. We proposed that the ethanol-induced alterations in microtubule dynamics may explain the ethanol-induced defects in membrane trafficking that have been previously documented. To test this, we compared the trafficking of selected proteins in control cells and cells treated with ethanol or with the histone deacetylase 6 inhibitor trichostatin A (TSA). We determined that exposure to 50 nM TSA for 30 minutes induced microtubule acetylation ( approximately 3-fold increase) and stability to the same extent as did ethanol. As shown previously in situ, the endocytic trafficking of the asialoglycoprotein receptor (ASGP-R) was impaired in ethanol-treated WIF-B cells. This impairment required ethanol metabolism and was likely mediated by acetaldehyde. TSA also impaired ASGP-R endocytic trafficking, but to a lesser extent. Similarly, both ethanol and TSA impaired transcytosis of the single-spanning apical resident aminopeptidase N (APN). For both ASGP-R and APN and for both treatments, the block in trafficking was internalization from the basolateral membrane. Interestingly, no changes in transcytosis of the glycophosphatidylinositol-anchored protein, 5'-nucleotidase, were observed, suggesting that increased microtubule acetylation and stability differentially regulate internalization. We further determined that albumin secretion was impaired in both ethanol-treated and TSA-treated cells, indicating that increased microtubule acetylation and stability also disrupted this transport step. CONCLUSION These results indicate that altered microtubule dynamics explain in part alcohol-induced defects in membrane trafficking.
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Affiliation(s)
- Rohan A. Joseph
- Department of Biology, The Catholic University of America, Washington, DC
| | - Blythe D. Shepard
- Department of Biology, The Catholic University of America, Washington, DC
| | | | - Tara M. Rutledge
- Department of Biology, The Catholic University of America, Washington, DC
| | - Dean J. Tuma
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE
| | - Pamela L. Tuma
- Department of Biology, The Catholic University of America, Washington, DC
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Abstract
Chronic ethanol consumption is associated with serious and potentially fatal alcohol-related liver injuries such as hepatomegaly, alcoholic hepatitis and cirrhosis. Moreover, it has been documented that the clinical progression of alcohol-induced liver damage may be associated with an increase in hepatocellular death that involves apoptotic mechanisms. Although much information has been learned about the clinical manifestations associated with alcohol-related diseases, the search continues for a better understanding of the molecular and/or cellular mechanisms by which ethanol exerts its deleterious effects such as the induction of pro-apoptotic mechanisms and related cell damaging events. As part of the effort to enhance our understanding of those particular cellular pathways and mechanisms associated with ethanol toxicity, researchers over the years have utilized a variety of model systems. Recently, work has come forth demonstrating the utility of a hybrid cell line (WIF-B) as a cell culture model system for the study of alcohol-associated alterations in hepatocellular mechanisms. Success with such emerging model systems could aid in the development of potential therapeutic treatments for the prevention of alcohol-induced apoptotic cell death that may ultimately serve as a significant target in delaying the onset and/or progression of clinical symptoms of alcohol-mediated liver disease. This review article summarizes the current understanding of ethanol-mediated modifications in cell survival and thus the promotion of pro-apoptotic events with emphasis on analyses made in various experimental model systems, particularly the more recently characterized WIF-B cell system.
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Affiliation(s)
- Benita L McVicker
- Veterans Affairs Medical Center, Research Service (151), 4101 Woolworth Avenue, Omaha, NE 68105, USA.
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26
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Osna NA, White RL, Todero S, McVicker BL, Thiele GM, Clemens DL, Tuma DJ, Donohue TM. Ethanol-induced oxidative stress suppresses generation of peptides for antigen presentation by hepatoma cells. Hepatology 2007; 45:53-61. [PMID: 17187415 DOI: 10.1002/hep.21442] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
UNLABELLED Processing of peptides for antigen presentation is catalyzed by antigen-trimming enzymes, including the proteasome and leucine aminopeptidase. Oxidative stress suppresses proteasome function. We hypothesized that in liver cells, processing of antigenic peptides is altered by ethanol metabolism. To address this issue, soluble extracts of ethanol-metabolizing VL-17A cells treated with 100 mM ethanol or left untreated were incubated with C-extended or N-extended 18-27 HBV core peptides. Peptide cleavage was measured by recovery after HPLC. Ethanol exposure to VL-17A cells increased CYP2E1 and decreased proteasome peptidase activities. The latter effect was prevented by treatment of cells with inhibitors, 4-methylpyrazole and diallyl sulfide. Ethanol treatment of VL-17A cells also reduced the activity of leucine aminopeptidase (LAP). Consequently, cleavage of both C-extended and N-extended peptides by cytosolic extracts was suppressed by pretreatment of cells with ethanol. Treatment of cells with interferon gamma, which enhances proteasome activity, did not reverse the effects of ethanol. Ethanol exerted similar effects on WIFB cells, indicating that its effects are not unique to one cell type. CONCLUSION Ethanol metabolism suppresses activities of antigen-trimming enzymes, thereby decreasing the cleavage of C-extended and N-extended peptides. This defect may potentially result in decreased MHC class I-restricted antigen presentation on virally infected liver cells.
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Affiliation(s)
- Natalia A Osna
- Liver Study Unit, The Omaha Veterans Affairs (VA) Medical Center, Omaha, NE 68105, USA.
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27
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McVicker BL, Tuma DJ, Kubik JL, Tuma PL, Casey CA. Ethanol-induced apoptosis in polarized hepatic cells possibly through regulation of the Fas pathway. Alcohol Clin Exp Res 2006; 30:1906-15. [PMID: 17067356 DOI: 10.1111/j.1530-0277.2006.00235.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND It has been noted that alcohol-related liver diseases can be associated with an increase in apoptotic hepatocellular death. Moreover, the promotion of hepatocyte apoptosis may be linked to signals emanating from death receptors, particularly Fas [CD95/apoptosis-inducing protein 1 (APO-1)]. In the present study, we utilized an in vitro hepatic culture model [hybrid of human fibroblast (WI 38) and rat hepatoma (Fao) cells, WIF-B cells] to study potential contributing mechanisms involved in hepatocellular apoptosis following ethanol administration. METHODS WIF-B cultures (differentiated hepatic cells that efficiently metabolize alcohol) were treated with or without ethanol and specific inhibitors of alcohol metabolism and cysteine protease activity, followed by morphological and biochemical examination of proapoptotic parameters. RESULTS The results of this work demonstrated that ethanol administration leads to an increase (45%-60%) in caspase-3 activity and that the induction of apoptosis was found to be linked to the metabolism of alcohol. Additionally, increases were observed in the activity of upstream initiator caspases (caspase-2 and caspase-8) that are directly related to membrane signaling events of death receptors such as Fas. Moreover, it was determined that the activation of caspase-3 could be blocked by the presence of a specific caspase-8 inhibitor, again linking death receptor-associated proteases to downstream effector caspase activity in alcohol-related death. Finally, ethanol administration was found to result in an increase in the amount of Fas protein present in the membrane fraction of the cell. The increase in membrane Fas protein indicates ligand-independent membrane targeting of Fas in the alcohol-treated cells that could potentially be a key signaling event in the induction of the proapoptotic caspase cascade. CONCLUSIONS The data presented here indicate that alcohol metabolism induces apoptosis in WIF-B cells that occurs, in part, by mechanisms involving signals emanating from death receptors.
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Affiliation(s)
- Benita L McVicker
- The Liver Study Unit, Department of Veterans Affairs Medical Center, 4101 Woolworth Avenue, Omaha, NE 68105, USA.
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28
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Kannarkat GT, Tuma DJ, Tuma PL. Microtubules are more stable and more highly acetylated in ethanol-treated hepatic cells. J Hepatol 2006; 44:963-70. [PMID: 16169115 DOI: 10.1016/j.jhep.2005.07.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Revised: 06/29/2005] [Accepted: 07/02/2005] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS Chronic alcohol consumption can lead to serious liver disease. Although the disease progression is clinically well-described, the molecular basis for alcohol-induced hepatotoxicity is not understood. METHODS We examined hepatocyte-specific, alcohol-induced alterations in microtubule dynamics in WIF-B cells. These cells provide an excellent model for studying alcohol-induced hepatotoxicity; they remain differentiated in culture and metabolize alcohol. RESULTS Consistent with reports in other hepatic systems, microtubule polymerization in ethanol-treated WIF-B cells was impaired. However, when viewed by epifluorescence, the microtubules in ethanol-treated cells resembled stable polymers. Antibodies to acetylated alpha-tubulin confirmed their identity morphologically and revealed biochemically that ethanol-treated cells had approximately three-fold more acetylated alpha-tubulin than control cells. Livers from ethanol-fed rats also contained increased levels of acetylated alpha-tubulin. Consistent with increased acetylated alpha-tubulin levels, microtubules in ethanol-treated WIF-B cells were more stable. Because stability increased with increased time of ethanol exposure or concentration, was prevented by 4-methylpyrazole and was potentiated by cyanamide, we conclude that increased acetylation requires alcohol metabolism and is likely to be mediated by acetaldehyde. CONCLUSIONS Ethanol metabolism impairs tubulin polymerization, but once microtubules are formed they are hyperstabilized. These ethanol-induced alterations in microtubule integrity likely have profound effects on hepatocyte function.
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Affiliation(s)
- George T Kannarkat
- Department of Biology, The Catholic University of America, 620 Michigan Avenue, NE, Washington, DC 20064, USA
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29
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Kim BJ, Hood BL, Aragon RA, Hardwick JP, Conrads TP, Veenstra TD, Song BJ. Increased oxidation and degradation of cytosolic proteins in alcohol-exposed mouse liver and hepatoma cells. Proteomics 2006; 6:1250-60. [PMID: 16408314 PMCID: PMC1368983 DOI: 10.1002/pmic.200500447] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We recently developed a sensitive method using biotin-N-maleimide (biotin-NM) as a probe to positively identify oxidized mitochondrial proteins. In this study, biotin-NM was used to identify oxidized cytosolic proteins in alcohol-fed mouse livers. Alcohol treatment for 6 wk elevated the levels of CYP2E1 and nitrotyrosine, a marker of oxidative stress. Markedly increased levels of oxidized proteins were detected in alcohol-fed mouse livers compared to pair-fed controls. The biotin-NM-labeled oxidized proteins from alcohol-exposed mouse livers were subsequently purified with streptavidin-agarose and resolved on 2-DE. More than 90 silver-stained protein spots that displayed differential intensities on 2-D gels were identified by MS. Peptide sequence analysis revealed that many enzymes or proteins involved in stress response, chaperone activity, intermediary metabolism, and antioxidant defense systems such as peroxiredoxin were oxidized after alcohol treatment. Smaller fragments of many proteins were repeatedly detected only in alcohol-fed mice, indicating that many oxidized proteins after alcohol exposure were degraded. Immunoblot results showed that the level of oxidized peroxiredoxin (inactivated) was markedly increased in the alcohol-exposed mouse livers and ethanol-sensitive hepatoma cells compared to the corresponding controls. Our results may explain the underlying mechanism for cellular dysfunction and increased susceptibility to other toxic agents following alcohol-mediated oxidative stress.
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Affiliation(s)
- Bong-Jo Kim
- Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892-9410, USA
| | - Brian L. Hood
- Laboratory of Proteomics and Analytical Technologies, SAIC-Frederick, Inc., Frederick, MD, USA and
| | - Richard A. Aragon
- Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892-9410, USA
| | - James P. Hardwick
- Department of Biochemistry, Northeastern Ohio University College of Medicine, Rootstown, OH, USA
| | - Thomas P. Conrads
- Laboratory of Proteomics and Analytical Technologies, SAIC-Frederick, Inc., Frederick, MD, USA and
| | - Timothy D. Veenstra
- Laboratory of Proteomics and Analytical Technologies, SAIC-Frederick, Inc., Frederick, MD, USA and
| | - Byoung J. Song
- Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892-9410, USA
- To whom correspondence should be addressed: Dr. B. J. Song, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, 9000 Rockville Pike, Bethesda, MD 20892-9410, USA. (e-mail); (Fax) 1-301-594-3113
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30
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Donohue TM, Osna NA, Clemens DL. Recombinant Hep G2 cells that express alcohol dehydrogenase and cytochrome P450 2E1 as a model of ethanol-elicited cytotoxicity. Int J Biochem Cell Biol 2006; 38:92-101. [PMID: 16181800 DOI: 10.1016/j.biocel.2005.07.010] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Accepted: 07/27/2005] [Indexed: 02/08/2023]
Abstract
HepG2 cells were transfected with recombinant plasmids, one carrying the murine alcohol dehydrogenase (ADH) gene and the other containing the gene encoding human cytochrome P450 2E1 (CYP2E1). One of recombinant clones called VL-17A exhibited ADH and CYP2E1 specific activities comparable to those in isolated rat hepatocytes. VL-17A cells oxidized ethanol and generated acetaldehyde, the levels of which depended upon the initial ethanol concentration. Compared with unexposed VL-17A cells, ethanol exposure increased the cellular redox (lactate:pyruvate ratio) and caused cell toxicity, indicated by increased leakage of lactate dehydrogenase into the medium,. Exposure of VL-17A cells to 100mM ethanol significantly elevated caspase 3 activity, an indicator of apoptosis, but this ethanol concentration did not affect caspase 3 activity in parental HepG2 cells. Because ethanol consumption causes a decline in hepatic protein catabolism, we examined the influence of ethanol exposure on proteasome activity in HepG2, VL-17A, E-47 (CYP2E1(+)) and VA-13 (ADH(+)) cells. Exposure to 100mM ethanol caused a 25% decline in the chymotrypsin-like activity of the proteasome in VL-17A cells, but the enzyme was unaffected in the other cell types. This inhibitory effect on the proteasome was blocked when ethanol metabolism was blocked by 4-methyl pyrazole. We conclude that recombinant VL-17A cells, which express both ADH and CYP2E1 exhibit hepatocyte-like characteristics in response to ethanol. Furthermore, the metabolism of ethanol by these cells via ADH and CYP2E1 is sufficient to bring about an inhibition of proteasome activity that may lead to apoptotic cell death.
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Sehgal S, Guerra MT, Kruglov EA, Wang J, Nathanson MH. Protein 4.1N does not interact with the inositol 1,4,5-trisphosphate receptor in an epithelial cell line. Cell Calcium 2005; 38:469-80. [PMID: 16122796 DOI: 10.1016/j.ceca.2005.06.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Accepted: 06/17/2005] [Indexed: 01/06/2023]
Abstract
Cytosolic Ca2+ regulates a variety of cell functions, and the spatial patterns of Ca2+ signals are responsible in part for the versatility of this second messenger. The subcellular distribution of the inositol 1,4,5-trisphosphate receptor (IP3R) is thought to regulate Ca2+-signaling patterns but little is known about how the distribution of the IP3R itself is regulated. Here we examined the relationship between the IP3R and the cytoskeletal linker protein 4.1N in the polarized WIF-B cell line because protein 4.1N regulates targeting of the type I IP3R in neurons, but WIF-B cells do not express this cytoskeletal protein. WIF-B cells expressed all three isoforms of the IP3R, and each isoform was distributed throughout the cell. These cells did not express the ryanodine receptor. Photorelease of microinjected, caged IP3 induced a rapid rise in cytosolic Ca2+, but the increase began uniformly throughout the cell rather than at a specific initiation site. Expression of protein 4.1N was not associated with redistribution of the IP3R or changes in Ca2+-signaling patterns. These findings are consistent with the hypothesis that the subcellular distribution of IP3R isoforms regulates the formation of Ca2+ waves, and the finding that interactions between protein 4.1N and the IP3R vary among cell types may provide an additional, tissue-specific mechanism to shape the pattern of Ca2+ waves.
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Affiliation(s)
- Sona Sehgal
- Department of Pediatrics, Yale University School of Medicine, New Haven, CT, USA
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32
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Peng X, Grosse B, Le Tiec B, Nicolas V, Delagebeaudeuf C, Bedda T, Decaens C, Cassio D. How to induce non-polarized cells of hepatic origin to express typical hepatocyte polarity: generation of new highly polarized cell models with developed and functional bile canaliculi. Cell Tissue Res 2005; 323:233-43. [PMID: 16231191 DOI: 10.1007/s00441-005-0067-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Accepted: 07/25/2005] [Indexed: 12/20/2022]
Abstract
Few in vitro models expressing complex hepatocyte polarity are available. We used the unpolarized rat Fao cell line to isolate the polarized WIF-B line. These complex rat-human hybrid cells form functional simple bile canaliculi. To obtain Fao-derived polarized models with a simpler chromosome content and developed bile canaliculi, we employed two approaches. Partial success was achieved with monochromosomal hybrids. As shown by the immunolocalization of apical, basolateral, and tight-junctional proteins, monochromosomal hybrid 11-3 cells were polarized. They formed simple functional bile canaliculi and transiently expressed the typical polarity of simple epithelial cells. One subclone blocked in this polarity state was isolated. A more robust approach was provided by spheroid culture, a three-dimensional system that strengthens cell-cell contacts. Transient spheroid culture induced irreversible polarization of Fao cells. This induction occurred in most spheroids (approximately 1% of the cells). From populations enriched in stably polarized cells, we generated new polarized cell models, designated Can. Can 3-1 cells formed simple functional bile canaliculi when plated at high density. Regardless of plating density, Can 9 and Can 10 cells formed long tubular branched canaliculi competent for vectorial transport of organic anions and bile acids, and involving several dozen adjacent cells. Thus, we have generated new cell models stably expressing typical hepatocyte polarity. Among these models, Can 9 and Can 10 are the first capable of forming functional, highly developed bile canaliculi similar to those formed in vivo.
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Affiliation(s)
- Xu Peng
- Inserm, U442, Orsay, 91400, France
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Moon KH, Kim BJ, Song BJ. Inhibition of mitochondrial aldehyde dehydrogenase by nitric oxide-mediated S-nitrosylation. FEBS Lett 2005; 579:6115-20. [PMID: 16242127 PMCID: PMC1350915 DOI: 10.1016/j.febslet.2005.09.082] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2005] [Accepted: 09/22/2005] [Indexed: 12/24/2022]
Abstract
Mitochondrial aldehyde dehydrogenase (ALDH2) is responsible for the metabolism of acetaldehyde and other toxic lipid aldehydes. Despite many reports about the inhibition of ALDH2 by toxic chemicals, it is unknown whether nitric oxide (NO) can alter the ALDH2 activity in intact cells or in vivo animals. The aim of this study was to investigate the effects of NO on ALDH2 activity in H4IIE-C3 rat hepatoma cells. NO donors such as S-nitrosoglutathione (GSNO), S-nitroso-N-acetylpenicillamine, and 3-morpholinosydnonimine significantly increased the nitrite concentration while they inhibited the ALDH2 activity. Addition of GSH-ethylester (GSH-EE) completely blocked the GSNO-mediated ALDH2 inhibition and increased nitrite concentration. To directly demonstrate the NO-mediated S-nitrosylation and inactivation, ALDH2 was immunopurified from control or GSNO-treated cells and subjected to immunoblot analysis. The anti-nitrosocysteine antibody recognized the immunopurified ALDH2 only from the GSNO-treated samples. All these results indicate that S-nitrosylation of ALDH2 in intact cells leads to reversible inhibition of ALDH2 activity.
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Affiliation(s)
| | | | - Byoung J. Song
- Corresponding author. Fax: +1 301 594 3113., E-mail address: (B.J. Song)
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