201
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Martínez-López N, Varela-Rey M, Fernández-Ramos D, Woodhoo A, Vázquez-Chantada M, Embade N, Espinosa-Hevia L, Bustamante FJ, Parada LA, Rodriguez MS, Lu SC, Mato JM, Martínez-Chantar ML. Activation of LKB1-Akt pathway independent of phosphoinositide 3-kinase plays a critical role in the proliferation of hepatocellular carcinoma from nonalcoholic steatohepatitis. Hepatology 2010; 52:1621-31. [PMID: 20815019 PMCID: PMC2967637 DOI: 10.1002/hep.23860] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
UNLABELLED LKB1, originally considered a tumor suppressor, plays an important role in hepatocyte proliferation and liver regeneration. Mice lacking the methionine adenosyltransferase (MAT) gene MAT1A exhibit a chronic reduction in hepatic S-adenosylmethionine (SAMe) levels, basal activation of LKB1, and spontaneous development of nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). These results are relevant for human health because patients with liver cirrhosis, who are at risk to develop HCC, have a marked reduction in hepatic MAT1A expression and SAMe synthesis. In this study, we isolated a cell line (SAMe-deficient [SAMe-D]) from MAT1A knockout (MAT1A-KO) mouse HCC to examine the role of LKB1 in the development of liver tumors derived from metabolic disorders. We found that LKB1 is required for cell survival in SAMe-D cells. LKB1 regulates Akt-mediated survival independent of phosphoinositide 3-kinase, adenosine monophosphate protein-activated kinase (AMPK), and mammalian target of rapamycin complex (mTORC2). In addition, LKB1 controls the apoptotic response through phosphorylation and retention of p53 in the cytoplasm and the regulation of herpesvirus-associated ubiquitin-specific protease (HAUSP) and Hu antigen R (HuR) nucleocytoplasmic shuttling. We identified HAUSP as a target of HuR. Finally, we observed cytoplasmic staining of p53 and p-LKB1(Ser428) in a NASH-HCC animal model (from MAT1A-KO mice) and in liver biopsies obtained from human HCC derived from both alcoholic steatohepatitis and NASH. CONCLUSION The SAMe-D cell line is a relevant model of HCC derived from NASH disease in which LKB1 is the principal conductor of a new regulatory mechanism and could be a practical tool for uncovering new therapeutic strategies.
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Affiliation(s)
- Nuria Martínez-López
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, Bizkaia, Spain.
| | - Marta Varela-Rey
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - David Fernández-Ramos
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Ashwin Woodhoo
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Mercedes Vázquez-Chantada
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Nieves Embade
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Luis Espinosa-Hevia
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | | | - Luis A Parada
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Manuel S Rodriguez
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Shelly C Lu
- Division of Gastrointestinal and Liver Diseases, USC Research Center for Liver Diseases, Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - José M Mato
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Maria L Martínez-Chantar
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
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202
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Fernández-Irigoyen J, Santamaría E, Chien YH, Hwu WL, Korman SH, Faghfoury H, Schulze A, Hoganson GE, Stabler SP, Allen RH, Wagner C, Mudd SH, Corrales FJ. Enzymatic activity of methionine adenosyltransferase variants identified in patients with persistent hypermethioninemia. Mol Genet Metab 2010; 101:172-7. [PMID: 20675163 DOI: 10.1016/j.ymgme.2010.07.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Revised: 07/08/2010] [Accepted: 07/08/2010] [Indexed: 01/12/2023]
Abstract
Methionine adenosyltransferases (MAT's) are central enzymes in living organisms that have been conserved with a high degree of homology among species. In the liver, MAT I and III, tetrameric and dimeric isoforms of the same catalytic subunit encoded by the gene MAT1A, account for the predominant portion of total body synthesis of S-adenosylmethionine (SAM), a versatile sulfonium ion-containing molecule involved in a variety of vital metabolic reactions and in the control of hepatocyte proliferation and differentiation. During the past 15years 28 MAT1A mutations have been described in patients with elevated plasma methionines, total homocysteines at most only moderately elevated, and normal levels of tyrosine and other aminoacids. In this study we describe functional analyses that determine the MAT and tripolyphosphatase (PPPase) activities of 18 MAT1A variants, six of them novel, and none of them previously assayed for activity. With the exception of G69S and Y92H, all recombinant proteins showed impairment (usually severe) of MAT activity. Tripolyphosphate (PPPi) hydrolysis was decreased only in some mutant proteins but, when it was decreased MAT activity was always also impaired.
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Affiliation(s)
- Joaquín Fernández-Irigoyen
- Division of Hepatology and Gene Therapy, Proteomics Unit, Center for Applied Medical Research (CIMA), University of Navarra, 31008 Pamplona, Spain
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203
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Dever JT, Elfarra AA. The biochemical and toxicological significance of hypermethionemia: new insights and clinical relevance. Expert Opin Drug Metab Toxicol 2010; 6:1333-46. [PMID: 20874374 DOI: 10.1517/17425255.2010.522177] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
IMPORTANCE OF THE FIELD Disrupted l-methionine (Met) metabolism can lead to hepatic, neurological and cardiovascular dysfunction in humans. Aberrant methyl group flux likely contributes to the development of these pathologies, but when patients also become hypermethionemic, additional toxicological mechanisms may be relevant. AREAS COVERED IN THIS REVIEW Following a discussion of the causes of hypermethionemia in humans, evidence for the toxicological roles and clinical significance of the Met transmethylation (TM), transamination (TA) and sulfoxidation (SO) pathways will be presented. WHAT THE READER WILL GAIN Recent data from freshly isolated mouse hepatocytes (FIMHs) confirmed previous in vivo results in rodents that Met TM is a detoxification pathway while Met TA leads to toxicity. Gender-related differences in Met accumulation and metabolism in FIMHs correlated with gender differences in toxicity. Data obtained from FIMHs also implicated Met SO in Met metabolism and toxicity. Currently, little is known about the mechanisms and biological significance of Met sulfoxidation in humans. TAKE HOME MESSAGE In hypermethionemic patients, clinical and dietary interventions should focus on increasing Met TM and decreasing Met TA and SO. Novel biomarkers of hypermethionemia in humans that correlate with pathological end points are needed to better understand the impact of the condition.
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Affiliation(s)
- Joseph T Dever
- University of Wisconsin-Madison, Department of Nutritional Sciences, Madison, WI 53706, USA
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204
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Evrard E, Marchand J, Theron M, Pichavant-Rafini K, Durand G, Quiniou L, Laroche J. Impacts of mixtures of herbicides on molecular and physiological responses of the European flounder Platichthys flesus. Comp Biochem Physiol C Toxicol Pharmacol 2010; 152:321-31. [PMID: 20566314 DOI: 10.1016/j.cbpc.2010.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 05/27/2010] [Accepted: 05/27/2010] [Indexed: 01/06/2023]
Abstract
The widespread use of pesticides results in a growing contamination of the aquatic environment. The effects of (1) a simple mixture of a glyphosate-based formulation and AMPA (Aminomethylphosphonic acid--a primary metabolite of glyphosate) and of (2) a more complex mixture of herbicides (glyphosate/AMPA/mecoprop/acetochlor/2,4D) were explored on the molecular and physiological responses of the European flounder Platichthys flesus, considering a long-term and environmentally realistic contamination. Molecular responses were identified using suppression subtractive hybridization on liver samples: the level of gene transcription was significantly different between contaminated fishes vs control ones for 532 sequences, after a 62-day contamination. Among them, 222 sequences were identified by homology with data-based sequences; they encoded several metabolic pathways including: methionine and lipid metabolism, immunity, protein regulation, coagulation and energetic metabolism. Expression pattern of nine transcripts in the liver was confirmed by real-time PCR. The molecular study underlined that potential markers of liver injury were expressed for both mixtures, in particular betaine homocysteine methyl transferase and chemotaxin. Physiological responses were analysed considering blood parameters and condition factor; after the two months contamination period; no significant physiological difference was detected between contaminated and control fish.
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205
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Chiba T, Seki A, Aoki R, Ichikawa H, Negishi M, Miyagi S, Oguro H, Saraya A, Kamiya A, Nakauchi H, Yokosuka O, Iwama A. Bmi1 promotes hepatic stem cell expansion and tumorigenicity in both Ink4a/Arf-dependent and -independent manners in mice. Hepatology 2010; 52:1111-23. [PMID: 20648475 DOI: 10.1002/hep.23793] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
UNLABELLED We previously reported that forced expression of Bmi1 (B lymphoma Moloney murine leukemia virus insertion region 1 homolog) in murine hepatic stem/progenitor cells purified from fetal liver enhances their self-renewal and drives cancer initiation. In the present study, we examined the contribution of the Ink4a/Arf tumor suppressor gene locus, one of the major targets of Bmi1, to stem cell expansion and cancer initiation. Bmi1(-/-) Delta-like protein (Dlk)(+) hepatic stem/progenitor cells showed de-repression of the Ink4a/Arf locus and displayed impaired growth activity. In contrast, Ink4a/Arf(-/-) Dlk(+) cells gave rise to considerably larger colonies containing a greater number of bipotent cells than wild-type Dlk(+) cells. Although Ink4a/Arf(-/-) Dlk(+) cells did not initiate tumors in recipient nonobese diabetic/severe combined immunodeficiency mice, enforced expression of Bmi1 in Ink4a/Arf(-/-) Dlk(+) cells further augmented their self-renewal capacity and resulted in tumor formation in vivo. Microarray analyses successfully identified five down-regulated genes as candidate downstream targets for Bmi1 in hepatic stem/progenitor cells. Of these genes, enforced expression of sex determining region Y-box 17 (Sox17) in Dlk(+) cells strongly suppressed colony propagation and tumor growth. CONCLUSION These results indicate that repression of targets of Bmi1 other than the Ink4a/Arf locus plays a crucial role in the oncogenic transformation of hepatic stem/progenitor cells. Functional analyses of Bmi1 target genes would be of importance to elucidate the molecular machinery underlying hepatic stem cell system and explore therapeutic approaches for the eradication of liver cancer stem cells.
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Affiliation(s)
- Tetsuhiro Chiba
- Department of Cellular and Molecular Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
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206
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Brown JM, Ball JG, Hogsett A, Williams T, Valentovic M. Temporal study of acetaminophen (APAP) and S-adenosyl-L-methionine (SAMe) effects on subcellular hepatic SAMe levels and methionine adenosyltransferase (MAT) expression and activity. Toxicol Appl Pharmacol 2010; 247:1-9. [PMID: 20450926 PMCID: PMC2906679 DOI: 10.1016/j.taap.2010.04.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2010] [Revised: 03/19/2010] [Accepted: 04/08/2010] [Indexed: 01/19/2023]
Abstract
Acetaminophen (APAP) is the leading cause of drug induced liver failure in the United States. Previous studies in our laboratory have shown that S-adenosyl methionine (SAMe) is protective for APAP hepatic toxicity. SAMe is critical for glutathione synthesis and transmethylation of nucleic acids, proteins and phospholipids which would facilitate recovery from APAP toxicity. SAMe is synthesized in cells through the action of methionine adenosyltransferase (MAT). This study tested the hypothesis that total hepatic and subcellular SAMe levels are decreased by APAP toxicity. Studies further examined MAT expression and activity in response to APAP toxicity. Male C57BL/6 mice (16-22 g) were treated with vehicle (Veh; water 15 ml/kg ip injections), 250 mg/kg APAP (15 ml/kg, ip), SAMe (1.25 mmol/kg) or SAMe administered 1h after APAP injection (SAMe and SAMe+APAP). Hepatic tissue was collected 2, 4, and 6h after APAP administration. Levels of SAMe and its metabolite S-adenosylhomocysteine (SAH) were determined by HPLC analysis. MAT expression was examined by Western blot. MAT activity was determined by fluorescence assay. Total liver SAMe levels were depressed at 4h by APAP overdose, but not at 2 or 6h. APAP depressed mitochondrial SAMe levels at 4 and 6h relative to the Veh group. In the nucleus, levels of SAMe were depressed below detectable limits 4h following APAP administration. SAMe administration following APAP (SAMe+APAP) prevented APAP associated decline in mitochondrial and nuclear SAMe levels. In conclusion, the maintenance of SAMe may provide benefit in preventing damage associated with APAP toxicity.
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Affiliation(s)
- J. Michael Brown
- Department of Pharmacology, Physiology, and Toxicology, Joan C. Edwards School of Medicine, Marshall University Huntington, WV 25755
| | - John G. Ball
- Department of Pharmacology, Physiology, and Toxicology, Joan C. Edwards School of Medicine, Marshall University Huntington, WV 25755
| | - Amy Hogsett
- Department of Pharmacology, Physiology, and Toxicology, Joan C. Edwards School of Medicine, Marshall University Huntington, WV 25755
| | - Tierra Williams
- Department of Pharmacology, Physiology, and Toxicology, Joan C. Edwards School of Medicine, Marshall University Huntington, WV 25755
| | - Monica Valentovic
- Department of Pharmacology, Physiology, and Toxicology, Joan C. Edwards School of Medicine, Marshall University Huntington, WV 25755
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207
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Strakova J, Williams KT, Gupta S, Schalinske KL, Kruger WD, Rozen R, Jiracek J, Li L, Garrow TA. Dietary intake of S-(alpha-carboxybutyl)-DL-homocysteine induces hyperhomocysteinemia in rats. Nutr Res 2010; 30:492-500. [PMID: 20797482 PMCID: PMC2929918 DOI: 10.1016/j.nutres.2010.06.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 06/30/2010] [Accepted: 06/30/2010] [Indexed: 11/16/2022]
Abstract
Betaine homocysteine S-methyltransferase (BHMT) catalyzes the transfer of a methyl group from betaine to homocysteine (Hcy), forming dimethylglycine and methionine. We previously showed that inhibiting BHMT in mice by intraperitoneal injection of S-(alpha-carboxybutyl)-DL-homocysteine (CBHcy) results in hyperhomocysteinemia. In the present study, CBHcy was fed to rats to determine whether it could be absorbed and cause hyperhomocysteinemia as observed in the intraperitoneal administration of the compound in mice. We hypothesized that dietary administered CBHcy will be absorbed and will result in the inhibition of BHMT and cause hyperhomocysteinemia. Rats were meal-fed every 8 hours an L-amino acid-defined diet either containing or devoid of CBHcy (5 mg per meal) for 3 days. The treatment decreased liver BHMT activity by 90% and had no effect on methionine synthase, methylenetetrahydrofolate reductase, phosphatidylethanolamine N-methyltransferase, and CTP:phosphocholine cytidylyltransferase activities. In contrast, cystathionine beta-synthase activity and immunodetectable protein decreased (56% and 26%, respectively) and glycine N-methyltransferase activity increased (52%) in CBHcy-treated rats. Liver S-adenosylmethionine levels decreased by 25% in CBHcy-treated rats, and S-adenosylhomocysteine levels did not change. Furthermore, plasma choline decreased (22%) and plasma betaine increased (15-fold) in CBHcy-treated rats. The treatment had no effect on global DNA and CpG island methylation, liver histology, and plasma markers of liver damage. We conclude that CBHcy-mediated BHMT inhibition causes an elevation in total plasma Hcy that is not normalized by the folate-dependent conversion of Hcy to methionine. Furthermore, metabolic changes caused by BHMT inhibition affect cystathionine beta-synthase and glycine N-methyltransferase activities, which further deteriorate plasma Hcy levels.
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Affiliation(s)
- Jana Strakova
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Kelly T. Williams
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011, USA
| | - Sapna Gupta
- Division of Population Science, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Kevin L. Schalinske
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011, USA
| | - Warren D. Kruger
- Division of Population Science, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Rima Rozen
- Departments of Human Genetics and Pediatrics, McGill University Health Centre-Montreal Children's Hospital, Montreal, Quebec, Canada
| | - Jiri Jiracek
- Biological Chemistry Department, Institute of Organic Chemistry and Biochemistry, Academy of Science of the Czech Republic, Prague 166 10, Czech Republic
| | - Lucas Li
- Metabolomics Center, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Timothy A. Garrow
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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208
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Varela-Rey M, Martínez-López N, Fernández-Ramos D, Embade N, Calvisi DF, Woodhoo A, Rodríguez J, Fraga MF, Julve J, Rodríguez-Millán E, Frades I, Torres L, Luka Z, Wagner C, Esteller M, Lu SC, Martínez-Chantar ML, Mato JM. Fatty liver and fibrosis in glycine N-methyltransferase knockout mice is prevented by nicotinamide. Hepatology 2010; 52:105-14. [PMID: 20578266 PMCID: PMC2921576 DOI: 10.1002/hep.23639] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
UNLABELLED Deletion of glycine N-methyltransferase (GNMT), the main gene involved in liver S-adenosylmethionine (SAM) catabolism, leads to the hepatic accumulation of this molecule and the development of fatty liver and fibrosis in mice. To demonstrate that the excess of hepatic SAM is the main agent contributing to liver disease in GNMT knockout (KO) mice, we treated 1.5-month-old GNMT-KO mice for 6 weeks with nicotinamide (NAM), a substrate of the enzyme NAM N-methyltransferase. NAM administration markedly reduced hepatic SAM content, prevented DNA hypermethylation, and normalized the expression of critical genes involved in fatty acid metabolism, oxidative stress, inflammation, cell proliferation, and apoptosis. More importantly, NAM treatment prevented the development of fatty liver and fibrosis in GNMT-KO mice. Because GNMT expression is down-regulated in patients with cirrhosis, and because some subjects with GNMT mutations have spontaneous liver disease, the clinical implications of the present findings are obvious, at least with respect to these latter individuals. Because NAM has been used for many years to treat a broad spectrum of diseases (including pellagra and diabetes) without significant side effects, it should be considered in subjects with GNMT mutations. CONCLUSION The findings of this study indicate that the anomalous accumulation of SAM in GNMT-KO mice can be corrected by NAM treatment leading to the normalization of the expression of many genes involved in fatty acid metabolism, oxidative stress, inflammation, cell proliferation, and apoptosis, as well as reversion of the appearance of the pathologic phenotype.
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Affiliation(s)
- Marta Varela-Rey
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Dgestivas (CIBERehd), Bizkaia, Spain
| | - Nuria Martínez-López
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Dgestivas (CIBERehd), Bizkaia, Spain
| | - David Fernández-Ramos
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Dgestivas (CIBERehd), Bizkaia, Spain
| | - Nieves Embade
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Dgestivas (CIBERehd), Bizkaia, Spain
| | - Diego F. Calvisi
- Institute of Pathology, Ernst Moritz Arndt University of Greifswald, Greifswald, Germany
| | - Aswhin Woodhoo
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Dgestivas (CIBERehd), Bizkaia, Spain
| | - Juan Rodríguez
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Dgestivas (CIBERehd), Bizkaia, Spain
| | - Mario F Fraga
- Department of Immunology and Oncology, National Center of Biotechnology, CNB-CSIC, Cantoblanco, Madrid, Spain
| | - Josep Julve
- Institut de Recerca de l'Hospital de la Santa Creu I Sant Pau, Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERdem), Barcelona, Spain
| | - Elisabeth Rodríguez-Millán
- Institut de Recerca de l'Hospital de la Santa Creu I Sant Pau, Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERdem), Barcelona, Spain
| | - Itziar Frades
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Dgestivas (CIBERehd), Bizkaia, Spain
| | - Luís Torres
- Departmento de Bioquímica y Biología Molecular, Universidad de Valencia, Spain
| | - Zigmund Luka
- Vanderbilt University School of Medicine, Department of Biochemistry, Nashville, Tennessee, USA
| | - Conrad Wagner
- Vanderbilt University School of Medicine, Department of Biochemistry, Nashville, Tennessee, USA
| | - Manel Esteller
- Cancer Epigenetics and Biology Program, Belvitge Biomedical Research Institute, Barcelona, Catalonia, Spain
| | - Shelly C Lu
- Division of Gastroenterology and Liver Diseases, University of Southern California Research Center for Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - M Luz Martínez-Chantar
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Dgestivas (CIBERehd), Bizkaia, Spain
| | - José M Mato
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Dgestivas (CIBERehd), Bizkaia, Spain
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209
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Tomasi ML, Ramani K, Lopitz-Otsoa F, Rodríguez MS, Li TWH, Ko K, Yang H, Bardag-Gorce F, Iglesias-Ara A, Feo F, Pascale MR, Mato JM, Lu SC. S-adenosylmethionine regulates dual-specificity mitogen-activated protein kinase phosphatase expression in mouse and human hepatocytes. Hepatology 2010; 51:2152-61. [PMID: 20196119 PMCID: PMC2905543 DOI: 10.1002/hep.23530] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
UNLABELLED Increased mitogen-activated protein kinase (MAPK) activity correlates with a more malignant hepatocellular carcinoma (HCC) phenotype. There is a reciprocal regulation between p44/42 MAPK (extracellular signal-regulated kinase [ERK]1/2) and the dual-specificity MAPK phosphatase MKP-1/DUSP1. ERK phosphorylates DUSP1, facilitating its proteasomal degradation, whereas DUSP1 inhibits ERK activity. Methionine adenosyltransferase 1a (Mat1a) knockout (KO) mice express hepatic S-adenosylmethionine (SAM) deficiency and increased ERK activity and develop HCC. The aim of this study was to examine whether DUSP1 expression is regulated by SAM and if so, elucidate the molecular mechanisms. Studies were conducted using Mat1a KO mice livers, cultured mouse and human hepatocytes, and 20S and 26S proteasomes. DUSP1 messenger RNA (mRNA) and protein levels were reduced markedly in livers of Mat1a KO mice and in cultured mouse and human hepatocytes with protein falling to lower levels than mRNA. SAM treatment protected against the fall in DUSP1 mRNA and protein levels in mouse and human hepatocytes. SAM increased DUSP1 transcription, p53 binding to DUSP1 promoter, and stability of its mRNA and protein. Proteasomal chymotrypsin-like and caspase-like activities were increased in Mat1a KO livers and cultured hepatocytes, which was blocked by SAM treatment. SAM inhibited chymotrypsin-like and caspase-like activities by 40% and 70%, respectively, in 20S proteasomes and caused rapid degradation of some of the 26S proteasomal subunits, which was blocked by the proteasome inhibitor MG132. SAM treatment in Mat1a KO mice for 7 days raised SAM, DUSP1, mRNA and protein levels and lowered proteosomal and ERK activities. CONCLUSION DUSP1 mRNA and protein levels are lower in Mat1a KO livers and fall rapidly in cultured hepatocytes. SAM treatment increases DUSP1 expression through multiple mechanisms, and this may suppress ERK activity and malignant degeneration.
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Affiliation(s)
- Maria Lauda Tomasi
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA,Division of Experimental Pathology and Oncology, Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - Komal Ramani
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Fernando Lopitz-Otsoa
- Cooperative Research Center in Biosciences, CIBERehd, Technology Park of Bizkaia, Derio, Bizkaia, Spain
| | - Manuel S. Rodríguez
- Cooperative Research Center in Biosciences, CIBERehd, Technology Park of Bizkaia, Derio, Bizkaia, Spain,Biochemistry Department, University of the Basque Country, Leioa, Bizkaia, Spain
| | - Tony W. H. Li
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Kwangsuk Ko
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Heping Yang
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | | | - Ainhoa Iglesias-Ara
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Francesco Feo
- Division of Experimental Pathology and Oncology, Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - Maria Rosa Pascale
- Division of Experimental Pathology and Oncology, Department of Biomedical Sciences, University of Sassari, Sassari, Italy
| | - José M. Mato
- Cooperative Research Center in Biosciences, CIBERehd, Technology Park of Bizkaia, Derio, Bizkaia, Spain
| | - Shelly C. Lu
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA
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Ogawa T, Fujii H, Yoshizato K, Kawada N. A human-type nonalcoholic steatohepatitis model with advanced fibrosis in rabbits. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:153-65. [PMID: 20489159 DOI: 10.2353/ajpath.2010.090895] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nonalcoholic steatohepatitis (NASH) progresses to liver fibrosis and cirrhosis, which can lead to life-threatening liver failure and the development of hepatocellular carcinoma. The aim of the present study was to create a rabbit model of NASH with advanced fibrosis (almost cirrhosis) by feeding the animals a diet supplemented with 0.75% cholesterol and 12% corn oil. After 9 months of feeding with this diet, the rabbits showed high total cholesterol levels in serum and liver tissues in the absence of insulin resistance. The livers became whitish and nodular. In addition, the number of rabbit macrophage antigen-positive cells and the expression of mRNAs for inflammatory cytokines showed a significant increase. Moreover, fibrotic septa composed of collagens and alpha-smooth muscle actin-positive cells were found between the central and portal veins, indicating alteration of the parenchymal architecture. There was also a marked increase of mRNAs for transforming growth factor-beta1 and collagen 1A1. Comprehensive analysis of protein and gene expression revealed an imbalance of the antioxidant system and methionine metabolism. We also found that ezetimibe attenuated steatohepatitis in this model. In conclusion, the present rabbit model of NASH features advanced fibrosis that is close to cirrhosis and may be useful for analyzing the molecular mechanisms of human NASH. Ezetimibe blunted the development of NASH in this model, suggesting its potential clinical usefulness for human steatohepatitis.
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Affiliation(s)
- Tomohiro Ogawa
- Department of Hepatology, Graduate School of Medicine, Osaka City University, 1-4-3, Asahimachi, Abeno, Osaka 545-8585, Japan
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211
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Lai CQ, Parnell LD, Troen AM, Shen J, Caouette H, Warodomwichit D, Lee YC, Crott JW, Qiu WQ, Rosenberg IH, Tucker KL, Ordovás JM. MAT1A variants are associated with hypertension, stroke, and markers of DNA damage and are modulated by plasma vitamin B-6 and folate. Am J Clin Nutr 2010; 91:1377-86. [PMID: 20335551 PMCID: PMC2854908 DOI: 10.3945/ajcn.2009.28923] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The S-adenosylmethionine synthetase type 1 (MAT1A) gene encodes a key enzyme in one-carbon nutrient metabolism. OBJECTIVE This study aimed to determine the association of MAT1A variants with homocysteine, DNA damage, and cardiovascular disease (CVD). DESIGN Eight variants of MAT1A were examined for associations with hypertension, stroke, CVD, homocysteine, and DNA damage in 1006 participants of the Boston Puerto Rican Health Study. Two variants were replicated in 1147 participants of the Nutrition, Aging, and Memory in Elders Study. RESULTS Two variants and haplotypes were strongly associated with hypertension and stroke, independent of methylenetetrahydrofolate reductase (MTHFR) variants. Homozygotes of the MAT1A d18777A (rs3851059) allele had a significantly greater likelihood of stroke (odds ratio: 4.30; 95% CI: 1.34, 12.19; P = 0.006), whereas 3U1510A (rs7087728) homozygotes had a lower likelihood of hypertension (odds ratio: 0.67; 95% CI: 0.48, 0.95; P = 0.022) and stroke (odds ratio: 0.35; 95% CI: 0.15, 0.82; P = 0.015). A similar trend of association was observed in a second elderly population. Furthermore, strong interactions between MAT1A genotypes and vitamin B-6 status were found. Carriers of the nonrisk allele 3U1510A had a lower 8-hydroxydeoxyguanosine concentration--a biomarker of oxidative DNA damage--when plasma vitamin B-6 was high, whereas homozygotes for the risk-allele 3U1510G had higher 8-hydroxydeoxyguanosine concentrations, regardless of vitamin B-6 status. CONCLUSIONS MAT1A variants were strongly associated with hypertension and stroke. Improving folate and vitamin B-6 status might decrease the CVD risk of only a subset of the population, depending on genotype. These findings suggest that impairments in methylation activity, independent of homocysteine, have an effect on CVD risk.
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Affiliation(s)
- Chao-Qiang Lai
- Nutrition and Genomics Laboratory, Jean Mayer-US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA.
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212
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Lee JE, Jacques PF, Dougherty L, Selhub J, Giovannucci E, Zeisel SH, Cho E. Are dietary choline and betaine intakes determinants of total homocysteine concentration? Am J Clin Nutr 2010; 91:1303-10. [PMID: 20219967 PMCID: PMC2854904 DOI: 10.3945/ajcn.2009.28456] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Elevated homocysteine concentrations are associated with an increased risk of cardiovascular disease and a decline in cognitive function. Intakes of choline and betaine, as methyl donors, may affect homocysteine concentrations. OBJECTIVE The objective was to examine whether choline and betaine intakes, assessed from food-frequency questionnaires, are associated with total plasma homocysteine concentrations under both fasting and post-methionine-load conditions in both pre- and post-folic acid fortification periods in the United States. DESIGN We assessed the association between choline and betaine intakes and fasting and post-methionine-load homocysteine concentrations using the US Department of Agriculture revised food-composition tables and evaluated whether the associations varied by folic acid fortification periods in 1325 male and 1407 female participants in the sixth examination (1995-1998) of the Framingham Offspring Study. RESULTS A higher choline-plus-betaine intake was associated with lower concentrations of post-methionine-load homocysteine; the multivariate geometric means were 24.1 micromol/L (95% CI: 23.4, 24.9 micromol/L) in the top quintile of intake and 25.0 micromol/L (95% CI: 24.2, 25.7 micromol/L) in the bottom quintile (P for trend = 0.01). We found an inverse association between choline-plus-betaine intake and fasting homocysteine concentrations; the multivariate geometric mean fasting homocysteine concentrations were 9.6 micromol/L (95% CI: 9.3, 9.9 micromol/L) in the top quintile and 10.1 micromol/L (95% CI: 9.8, 10.4 micromol/L) in the bottom quintile (P for trend < 0.001). When we stratified by plasma folate and vitamin B-12 concentrations, the inverse association was limited to participants with low plasma folate or vitamin B-12 concentrations. In the postfortification period, the inverse association between choline-plus-betaine intake and either fasting or post-methionine-load homocysteine was no longer present. CONCLUSIONS Choline and betaine intakes were associated with both fasting and post-methionine-load total homocysteine concentrations, especially in participants with low folate and vitamin B-12 status. The inverse association between choline and betaine intakes and homocysteine concentrations was no longer present in the postfortification period.
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Affiliation(s)
- Jung Eun Lee
- Department of Food and Nutrition, Sookmyung Women's University, Seoul, Republic of Korea
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213
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Vázquez-Chantada M, Fernández-Ramos D, Embade N, Martínez-Lopez N, Varela-Rey M, Woodhoo A, Luka Z, Wagner C, Anglim PP, Finnell RH, Caballería J, Laird-Offringa IA, Gorospe M, Lu SC, Mato JM, Martínez-Chantar ML. HuR/methyl-HuR and AUF1 regulate the MAT expressed during liver proliferation, differentiation, and carcinogenesis. Gastroenterology 2010; 138:1943-53. [PMID: 20102719 PMCID: PMC2860011 DOI: 10.1053/j.gastro.2010.01.032] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 12/18/2009] [Accepted: 01/14/2010] [Indexed: 01/15/2023]
Abstract
BACKGROUND & AIMS Hepatic de-differentiation, liver development, and malignant transformation are processes in which the levels of hepatic S-adenosylmethionine are tightly regulated by 2 genes: methionine adenosyltransferase 1A (MAT1A) and methionine adenosyltransferase 2A (MAT2A). MAT1A is expressed in the adult liver, whereas MAT2A expression primarily is extrahepatic and is associated strongly with liver proliferation. The mechanisms that regulate these expression patterns are not completely understood. METHODS In silico analysis of the 3' untranslated region of MAT1A and MAT2A revealed putative binding sites for the RNA-binding proteins AU-rich RNA binding factor 1 (AUF1) and HuR, respectively. We investigated the posttranscriptional regulation of MAT1A and MAT2A by AUF1, HuR, and methyl-HuR in the aforementioned biological processes. RESULTS During hepatic de-differentiation, the switch between MAT1A and MAT2A coincided with an increase in HuR and AUF1 expression. S-adenosylmethionine treatment altered this homeostasis by shifting the balance of AUF1 and methyl-HuR/HuR, which was identified as an inhibitor of MAT2A messenger RNA (mRNA) stability. We also observed a similar temporal distribution and a functional link between HuR, methyl-HuR, AUF1, and MAT1A and MAT2A during fetal liver development. Immunofluorescent analysis revealed increased levels of HuR and AUF1, and a decrease in methyl-HuR levels in human livers with hepatocellular carcinoma (HCC). CONCLUSIONS Our data strongly support a role for AUF1 and HuR/methyl-HuR in liver de-differentiation, development, and human HCC progression through the posttranslational regulation of MAT1A and MAT2A mRNAs.
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Affiliation(s)
- Mercedes Vázquez-Chantada
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - David Fernández-Ramos
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Nieves Embade
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Nuria Martínez-Lopez
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Marta Varela-Rey
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Ashwin Woodhoo
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Zigmund Luka
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37232-0146, USA
| | - Conrad Wagner
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37232-0146, USA, Tennessee Valley Department of Medical Affairs Medical Center, Nashville, TN, USA
| | - Paul P. Anglim
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9176, USA
| | - Richard H. Finnell
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030, USA
| | | | - Ite A. Laird-Offringa
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9176, USA
| | - Myriam Gorospe
- Laboratory of Cellular and Molecular Biology, National Institute on Aging-Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Shelly C Lu
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University Southern California, Los Angeles, CA 90033, USA
| | - José M Mato
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - M Luz Martínez-Chantar
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
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Korendyaseva TK, Martinov MV, Dudchenko AM, Vitvitsky VM. Distribution of methionine between cells and incubation medium in suspension of rat hepatocytes. Amino Acids 2010; 39:1281-9. [PMID: 20309593 DOI: 10.1007/s00726-010-0563-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2009] [Accepted: 03/10/2010] [Indexed: 01/18/2023]
Abstract
Methionine is an essential amino acid involved in many significant intracellular processes. Aberrations in methionine metabolism are associated with a number of complex pathologies. Liver plays a key role in regulation of blood methionine level. Investigation of methionine distribution between hepatocytes and medium is crucial for understanding the mechanisms of this regulation. For the first time, we analyzed the distribution of methionine between hepatocytes and incubation medium using direct measurements of methionine concentrations. Our results revealed a fast and reversible transport of methionine through the cell membrane that provides almost uniform distribution of methionine between hepatocytes and incubation medium. The steady-state ratio between intracellular and extracellular methionine concentrations was established within a few minutes. This ratio was found to be 1.06±0.38, 0.89±0.26, 0.67±0.16 and 0.82±0.06 at methionine concentrations in the medium of 64±19, 152±39, 413±55, and 1,204±104 μmol/L, respectively. The fast and uniform distribution of methionine between hepatocytes and extracellular compartments provides a possibility for effective regulation of blood methionine levels due to methionine metabolism in hepatocytes.
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Affiliation(s)
- Tatyana K Korendyaseva
- National Research Center for Hematology, Novozykovsky proezd, 4a, Moscow, 125167, Russia
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215
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Cederbaum AI. Hepatoprotective effects of S-adenosyl-L-methionine against alcohol- and cytochrome P450 2E1-induced liver injury. World J Gastroenterol 2010; 16:1366-76. [PMID: 20238404 PMCID: PMC2842529 DOI: 10.3748/wjg.v16.i11.1366] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [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
S-adenosyl-L-methionine (SAM) acts as a methyl donor for methylation reactions and participates in the synthesis of glutathione. SAM is also a key metabolite that regulates hepatocyte growth, differentiation and death. Hepatic SAM levels are decreased in animal models of alcohol liver injury and in patients with alcohol liver disease or viral cirrhosis. This review describes the protection by SAM against alcohol and cytochrome P450 2E1-dependent cytotoxicity both in vitro and in vivo and evaluates mechanisms for this protection.
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216
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Kirpich IA, Gobejishvili LN, Bon Homme M, Waigel S, Cave M, Arteel G, Barve SS, McClain CJ, Deaciuc IV. Integrated hepatic transcriptome and proteome analysis of mice with high-fat diet-induced nonalcoholic fatty liver disease. J Nutr Biochem 2010; 22:38-45. [PMID: 20303728 DOI: 10.1016/j.jnutbio.2009.11.009] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 11/10/2009] [Accepted: 11/17/2009] [Indexed: 12/26/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the most common form of liver disease in the US and refers to a wide spectrum of liver damage, including simple steatosis, steatohepatitis, fibrosis and cirrhosis. The goal of the present study was to achieve a more detailed understanding of the molecular changes in response to high fat-induced liver steatosis through the identification of a differentially expressed liver transcriptome and proteome. Male C57/BL6 mice fed a high-fat lard diet for 8 weeks developed visceral obesity and hepatic steatosis characterized by significantly increased liver and plasma free fatty acid and triglyceride levels and plasma alanine aminotransferase activities. Transcriptome analysis demonstrated that, compared to the control diet (CD), high-fat diet changed the expression of 309 genes (132 up- and 177 down-regulated; by a twofold change and more, P<.05). Multiple genes encoding proteins involved in lipogenesis were down-regulated, whereas genes involved in fatty acid oxidation were up-regulated. Proteomic analysis revealed 12 proteins which were differentially expressed. Of these, glutathione S-transferases mu1 and pi1 and selenium-binding protein 2 were decreased at both the gene and protein levels. This is the first study to perform a parallel transcriptomic and proteomic analysis of diet-induced hepatic steatosis. Several key pathways involving xenobiotic and lipid metabolism, the inflammatory response and cell-cycle control were identified. These pathways provide targets for future mechanistic and therapeutic studies as related to the development and prevention of NAFLD.
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Affiliation(s)
- Irina A Kirpich
- Department of Internal Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Louisville, Louisville, KY 40202, USA
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217
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Ariz U, Mato JM, Lu SC, Martínez Chantar ML. Nonalcoholic steatohepatitis, animal models, and biomarkers: what is new? Methods Mol Biol 2010; 593:109-36. [PMID: 19957147 DOI: 10.1007/978-1-60327-194-3_6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a clinicopathological term that encompasses a spectrum of abnormalities ranging from simple triglyceride accumulation in the hepatocytes (hepatic steatosis) to hepatic steatosis with inflammation (steatohepatitis, also known as nonalcoholic steatohepatitis or NASH). NASH can also progress to cirrhosis and hepatocellular carcinoma (HCC). Steatohepatitis has been estimated to affect around 5% of the total population and 20% of those who are overweight. The mechanisms leading to NASH and its progression to cirrhosis and HCC remain unclear, but it is a condition typically associated with obesity, insulin resistance, diabetes, and hypertriglyceridemia. This point corroborates the need for animal models and molecular markers that allow us to understand the mechanisms underlying this disease. Nowadays, there are numerous mice models to study abnormal liver function such as steatosis, NASH, and hepatocellular carcinoma. The study of the established animal models has provided many clues in the pathogenesis of steatosis and steatohepatitis, although these remain incompletely understood and no mice model completely fulfills the clinical features observed in humans. In addition, there is a lack of accurate sensitive diagnostic tests that do not involve invasive procedures. Current laboratory tests include some biochemical analysis, but their utility for diagnosing NASH is still poor. For that reason, a great effort is being made toward the identification and validation of novel biomarkers to assess NASH using high-throughput analysis based on genomics, proteomics, and metabolomics. The most recent discoveries and their validation will be discussed.
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Affiliation(s)
- Usue Ariz
- Metabolomics, Parque Technológico de Bizkaia, Derio, Spain
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218
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Espe M, Rathore RM, Du ZY, Liaset B, El-Mowafi A. Methionine limitation results in increased hepatic FAS activity, higher liver 18:1 to 18:0 fatty acid ratio and hepatic TAG accumulation in Atlantic salmon, Salmo salar. Amino Acids 2010; 39:449-60. [PMID: 20112035 DOI: 10.1007/s00726-009-0461-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Accepted: 12/21/2009] [Indexed: 01/16/2023]
Abstract
The current experiment aimed to study whether interactions with lipid metabolism possibly might explain the relative increased liver weight obtained in fish fed sub-optimal methionine levels. A basal diet based on a blend of plant proteins which is low in methionine (1.6 g Met/16 g N) was compared to a methionine adequate diet (2.2 g Met/16 g N) prepared by adding DL-methionine (2.4 g/kg) to the basal diet in the expense of wheat grain. Fish oil was used as the lipid source. The diets were balanced in all nutrients except methionine. The diets were fed to Atlantic salmon (500 g BW) for a period of 3 months. Feed intake did not differ, rendering the intake of all nutrients except methionine equal. Fish fed the low methionine diet had an increased liver size relative to body weight, indicating fat deposition in the liver. Fish given the sub-optimal methionine diet showed about six times higher fatty acid synthase (FAS) activity as compared to the fish fed the adequate methionine diet, indicating a higher de novo lipogenesis. A significant rise in the liver 18:1 to 18:0 fatty acid ratios also supported storage of lipids over fatty acid oxidation. Indeed, methionine limitation resulted in significantly higher TAG concentrations in the liver. Sub-optimal dietary methionine also resulted in lower hepatic taurine concentrations and the total bile acids concentrations were reduced in faeces and tended to be reduced in plasma. Taken together, our data show that salmon fed sub-optimal methionine levels had increased relative liver weight and developed signs commonly described in the early stage of non-alcoholic fatty liver disease in rodent models (increased FAS activity, changed fatty acid ratios and TAG accumulation).
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Affiliation(s)
- Marit Espe
- National Institute of Nutrition and Seafood Research, PO Box 2029, 5817, Nordnes, Norway.
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219
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Powell CL, Bradford BU, Craig CP, Tsuchiya M, Uehara T, O'Connell TM, Pogribny IP, Melnyk S, Koop DR, Bleyle L, Threadgill DW, Rusyn I. Mechanism for prevention of alcohol-induced liver injury by dietary methyl donors. Toxicol Sci 2010; 115:131-9. [PMID: 20118189 DOI: 10.1093/toxsci/kfq031] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Alcohol-induced liver injury (ALI) has been associated with, among other molecular changes, abnormal hepatic methionine metabolism, resulting in decreased levels of S-adenosylmethionine (SAM). Dietary methyl donor supplements such as SAM and betaine mitigate ALI in animal models; however, the mechanisms of protection remain elusive. It has been suggested that methyl donors may act via attenuation of alcohol-induced oxidative stress. We hypothesized that the protective action of methyl donors is mediated by an effect on the oxidative metabolism of alcohol in the liver. Male C57BL/6J mice were administered a control high-fat diet or diet enriched in methyl donors with or without alcohol for 4 weeks using the enteral alcohol feeding model. As expected, attenuation of ALI and an increase in reduced glutathione:oxidized glutathione ratio were achieved with methyl donor supplementation. Interestingly, methyl donors led to a 35% increase in blood alcohol elimination rate, and while there was no effect on alcohol metabolism in the stomach, a profound effect on liver alcohol metabolism was observed. The catalase-dependent pathway of alcohol metabolism was induced, yet the increase in CYP2E1 activity by alcohol was blunted, which may be mitigating production of oxidants. Additional factors contributing to the protective effects of methyl donors in ALI were increased activity of low- and high-K(m) aldehyde dehydrogenases leading to lower hepatic acetaldehyde, maintenance of the efficient mitochondrial energy metabolism, and promotion of peroxisomal beta-oxidation. Profound changes in alcohol metabolism represent additional important mechanism of the protective effect of methyl donors in ALI.
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Affiliation(s)
- Christine L Powell
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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220
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Fiorentino L, Vivanti A, Cavalera M, Marzano V, Ronci M, Fabrizi M, Menini S, Pugliese G, Menghini R, Khokha R, Lauro R, Urbani A, Federici M. Increased tumor necrosis factor alpha-converting enzyme activity induces insulin resistance and hepatosteatosis in mice. Hepatology 2010; 51:103-10. [PMID: 19877183 DOI: 10.1002/hep.23250] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
UNLABELLED Tumor necrosis factor alpha-converting enzyme (TACE, also known as ADAM17) was recently involved in the pathogenesis of insulin resistance. We observed that TACE activity was significantly higher in livers of mice fed a high-fat diet (HFD) for 1 month, and this activity was increased in liver > white adipose tissue > muscle after 5 months compared with chow control. In mouse hepatocytes, C(2)C(12) myocytes, and 3T3F442A adipocytes, TACE activity was triggered by palmitic acid, lipolysaccharide, high glucose, and high insulin. TACE overexpression significantly impaired insulin-dependent phosphorylation of AKT, GSK3, and FoxO1 in mouse hepatocytes. To test the role of TACE activation in vivo, we used tissue inhibitor of metalloproteinase 3 (Timp3) null mice, because Timp3 is the specific inhibitor of TACE and Timp3(-/-) mice have higher TACE activity compared with wild-type (WT) mice. Timp3(-/-) mice fed a HFD for 5 months are glucose-intolerant and insulin-resistant; they showed macrovesicular steatosis and ballooning degeneration compared with WT mice, which presented only microvesicular steatosis. Shotgun proteomics analysis revealed that Timp3(-/-) liver showed a significant differential expression of 38 proteins, including lower levels of adenosine kinase, methionine adenosysltransferase I/III, and glycine N-methyltransferase and higher levels of liver fatty acid-binding protein 1. These changes in protein levels were also observed in hepatocytes infected with adenovirus encoding TACE. All these proteins play a role in fatty acid uptake, triglyceride synthesis, and methionine metabolism, providing a molecular explanation for the increased hepatosteatosis observed in Timp3(-/-) compared with WT mice. CONCLUSION We have identified novel mechanisms, governed by the TACE-Timp3 interaction, involved in the determination of insulin resistance and liver steatosis during overfeeding in mice.
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Affiliation(s)
- Loredana Fiorentino
- Department of Internal Medicine, University of Rome Tor Vergata, Rome, Italy
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221
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Diesen DL, Kuo PC. Nitric oxide and redox regulation in the liver: Part I. General considerations and redox biology in hepatitis. J Surg Res 2009; 162:95-109. [PMID: 20444470 DOI: 10.1016/j.jss.2009.09.019] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 09/01/2009] [Accepted: 09/04/2009] [Indexed: 12/16/2022]
Abstract
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are created in normal hepatocytes and are critical for normal physiologic processes, including oxidative respiration, growth, regeneration, apoptosis, and microsomal defense. When the levels of oxidation products exceed the capacity of normal antioxidant systems, oxidative stress occurs. This type of stress, in the form of ROS and RNS, can be damaging to all liver cells, including hepatocytes, Kupffer cells, stellate cells, and endothelial cells, through induction of inflammation, ischemia, fibrosis, necrosis, apoptosis, or through malignant transformation by damaging lipids, proteins, and/or DNA. In Part I of this review, we will discuss basic redox biology in the liver, including a review of ROS, RNS, and antioxidants, with a focus on nitric oxide as a common source of RNS. We will then review the evidence for oxidative stress as a mechanism of liver injury in hepatitis (alcoholic, viral, nonalcoholic). In Part II of this review, we will review oxidative stress in common pathophysiologic conditions, including ischemia/reperfusion injury, fibrosis, hepatocellular carcinoma, iron overload, Wilson's disease, sepsis, and acetaminophen overdose. Finally, biomarkers, proteomic, and antioxidant therapies will be discussed as areas for future therapeutic interventions.
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Affiliation(s)
- Diana L Diesen
- Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA
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Asano T, Watanabe K, Kubota N, Gunji T, Omata M, Kadowaki T, Ohnishi S. Adiponectin knockout mice on high fat diet develop fibrosing steatohepatitis. J Gastroenterol Hepatol 2009; 24:1669-76. [PMID: 19788607 DOI: 10.1111/j.1440-1746.2009.06039.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND AIM Low levels of serum adiponectin have been reported to be associated with obesity, diabetes, and non-alcoholic steatohepatitis (NASH), as well as several malignancies. Adiponectin knockout (KO) mice have been reported to cause insulin resistance and neointimal formation of the artery. We used adiponectin KO mice fed a high fat (HF) diet, and investigated the effect of adiponectin on the progression of steatohepatitis and carcinogenesis in vivo. METHODS Adiponectin KO mice and wild type (WT) mice were fed a HF diet or normal chow for the periods of 24 and 48 weeks. The HF diet contained 60% of calories from fat. RESULTS The adiponectin KO mice on the HF diet showed obesity, marked elevation of serum transaminase levels, and hyperlipidemia. At 24 weeks, hepatic expression of tumor necrosis factor-alpha and procollagen alpha (I) was higher in KO mice as compared with WT mice. At 48 weeks, liver triglyceride contents in KO mice on normal chow were significantly higher than those in WT mice. Hepatocyte ballooning, spotty necrosis, and pericellular fibrosis around central veins were observed in KO mice on the HF diet. The pericellular fibrosis was more severe in KO mice on the HF diet than that in WT mice (1.62% vs 1.16%, P = 0.033). Liver adenoma and hyperplastic nodules developed in a KO mouse on the HF diet at 48 weeks (12.5%, n = 1/8), whereas no tumor was detected in WT mice (n = 10). CONCLUSIONS Adiponectin may play a protective role in the progression of NASH in the early stages by suppressing tumor necrosis factor-alpha expression and liver fibrosis.
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Affiliation(s)
- Takeharu Asano
- Department of Gastroenterology, Graduate School of Medicine, University of Tokyo, Tokyo 113-8655, Japan
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223
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Varela-Rey M, Fernández-Ramos D, Martínez-López N, Embade N, Gómez-Santos L, Beraza N, Vázquez-Chantada M, Rodríguez J, Luka Z, Wagner C, Lu SC, Martínez-Chantar ML, Mato JM. Impaired liver regeneration in mice lacking glycine N-methyltransferase. Hepatology 2009; 50:443-52. [PMID: 19582817 PMCID: PMC2805126 DOI: 10.1002/hep.23033] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
UNLABELLED Hepatic S-adenosylmethionine (SAMe) is maintained constant by the action of methionine adenosyltransferase I/III (MATI/III), which converts methionine into SAMe and glycine N-methyltransferase (GNMT), which eliminates excess SAMe to avoid aberrant methylation reactions. During liver regeneration after partial hepatectomy (PH) MATI/III activity is inhibited leading to a decrease in SAMe. This injury-related reduction in SAMe promotes hepatocyte proliferation because SAMe inhibits hepatocyte DNA synthesis. In MATI/III-deficient mice, hepatic SAMe is reduced, resulting in uncontrolled hepatocyte growth and impaired liver regeneration. These observations suggest that a reduction in SAMe is crucial for successful liver regeneration. In support of this hypothesis we report that liver regeneration is impaired in GNMT knockout (GNMT-KO) mice. Liver SAMe is 50-fold higher in GNMT-KO mice than in control animals and is maintained constant following PH. Mortality after PH was higher in GNMT-KO mice than in control animals. In GNMT-KO mice, nuclear factor kappaB (NFkappaB), signal transducer and activator of transcription-3 (STAT3), inducible nitric oxide synthase (iNOS), cyclin D1, cyclin A, and poly (ADP-ribose) polymerase were activated at baseline. PH in GNMT-KO mice was followed by the inactivation of STAT3 phosphorylation and iNOS expression. NFkappaB, cyclin D1 and cyclin A were not further activated after PH. The LKB1/AMP-activated protein kinase/endothelial nitric oxide synthase cascade was inhibited, and cytoplasmic HuR translocation was blocked despite preserved induction of DNA synthesis in GNMT-KO after PH. Furthermore, a previously unexpected relationship between AMPK phosphorylation and NFkappaB activation was uncovered. CONCLUSION These results indicate that multiple signaling pathways are impaired during the liver regenerative response in GNMT-KO mice, suggesting that GNMT plays a critical role during liver regeneration, promoting hepatocyte viability and normal proliferation.
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Affiliation(s)
- Marta Varela-Rey
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - David Fernández-Ramos
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Nuria Martínez-López
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Nieves Embade
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Laura Gómez-Santos
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Naiara Beraza
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Mercedes Vázquez-Chantada
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Juan Rodríguez
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Zigmund Luka
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37232-0146
| | - Conrad Wagner
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37232-0146.,Tennessee Valley Department of Medical Affairs Medical Center, Nashville, TN 37212
| | - Shelly C Lu
- Division of Gastrointestinal and Liver Diseases, USC Research Center for Liver Diseases, Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033
| | - M Luz Martínez-Chantar
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - José M Mato
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
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224
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Lu SC, Ramani K, Ou X, Lin M, Yu V, Ko K, Park R, Bottiglieri T, Tsukamoto H, Kanel G, French SW, Mato JM, Moats R, Grant E. S-adenosylmethionine in the chemoprevention and treatment of hepatocellular carcinoma in a rat model. Hepatology 2009; 50:462-71. [PMID: 19444874 PMCID: PMC2754739 DOI: 10.1002/hep.22990] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
UNLABELLED Hepatocellular carcinoma (HCC) remains a common cancer worldwide that lacks effective chemoprevention or treatment. Chronic liver disease often leads to impaired hepatic S-adenosylmethionine (SAMe) biosynthesis, and mice with SAMe deficiency develop HCC spontaneously. SAMe is antiapoptotic in normal hepatocytes but proapoptotic in cancerous hepatocytes. The present study investigated SAMe's effectiveness in prevention and treatment of HCC. Two weeks after injecting 2.5 million H4IIE cells into the liver parenchyma of ACI rats, they typically form a 1-cm tumor. When SAMe (150 mg/kg/day) was delivered through continuous intravenous infusion, hepatic SAMe levels reached 0.7 mM (over 10-fold) 24 hours later. This regimen, started 1 day after injecting H4IIE cells and continued for 10 days, was able to reduce tumor establishment and growth. However, if intravenous SAMe was started after HCC had already developed, it was ineffective in reducing tumor growth for 24 days. Although plasma SAMe levels remained elevated, hepatic SAMe levels were minimally increased (30% higher). Chronic SAMe administration led to induction of hepatic methyltransferases, which prevented SAMe accumulation. To see if SAMe's preventive effect on tumor establishment involves angiogenesis, the effect of SAMe on angiogenesis genes was studied. SAMe treatment of H4IIE cells altered the expression of several genes with the net effect of inhibiting angiogenesis. These changes were confirmed at the protein level and functionally in human umbilical vein endothelial cells. CONCLUSION SAMe is effective in preventing HCC establishment but ineffective in treating established HCC because of induction of hepatic methyltransferases, which prevents SAMe level to reach high enough to kill liver cancer cells. SAMe's chemopreventive effect may be related to its proapoptotic action and its ability to inhibit angiogenesis.
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Affiliation(s)
- Shelly C. Lu
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, California 90033,Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine USC, Los Angeles, California 90033
| | - Komal Ramani
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, California 90033,Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine USC, Los Angeles, California 90033
| | - Xiaopeng Ou
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, California 90033
| | - Mark Lin
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, California 90033
| | - Victor Yu
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, California 90033
| | - Kwangsuk Ko
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, California 90033
| | - Ryan Park
- Department of Radiology, Keck School of Medicine USC, Los Angeles, California 90033
| | - Teodoro Bottiglieri
- Institute of Metabolic Disease, Baylor University Medical Center, Dallas Texas
| | - Hidekazu Tsukamoto
- Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine USC, Los Angeles, California 90033,Department of Pathology, Keck School of Medicine USC, Los Angeles, California 90033 and Department of Veteran sAffairs Greater Los Angeles Healthcare System, Los Angeles
| | - Gary Kanel
- Department of Pathology, Keck School of Medicine USC, Los Angeles, California 90033 and Department of Veteran sAffairs Greater Los Angeles Healthcare System, Los Angeles
| | - Samuel W. French
- Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine USC, Los Angeles, California 90033,Department of Pathology, Harbor-UCLA Medical Center, Torrance, CA 90509
| | - José M. Mato
- CIC bioGUNE, Ciberehd, Technology Park of Bizkaia, 48160 Derio, Bizkaia, Spain
| | - Rex Moats
- Department of Radiology, Keck School of Medicine USC, Los Angeles, California 90033
| | - Edward Grant
- Department of Radiology, Keck School of Medicine USC, Los Angeles, California 90033
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225
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Karas-Kuzelicki N, Mlinaric-Rascan I. Individualization of thiopurine therapy: thiopurine S-methyltransferase and beyond. Pharmacogenomics 2009; 10:1309-22. [DOI: 10.2217/pgs.09.78] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The metabolism of a given drug depends, not solely on a particular enzyme, but rather on a complex metabolic network. Thiopurine S-methyltransferase (TPMT) catalyzes the methylation, and thus deactivation, of 6-mercaptopurine, a thiopurine used in the treatment of acute lymphoblastic leukemia. Low TPMT activity has been associated with severe toxicity of 6-mercaptopurine. Determination of mutations in the TPMT gene before starting 6-mercaptopurine therapy constitutes a quick, simple and cost-effective strategy to individualize thiopurine dosing. However, TPMT phenotype-to-genotype correlation is not complete, indicating a need for identification of novel biomarkers. Based on our recent findings and reviewing seemingly unrelated literature reports we present a synthesis of the current understanding of factors that influence TPMT activity and consequently modulate responsiveness to thiopurine treatment. Identification and understanding of these factors is crucial for improving the efficacy and safety of acute lymphoblastic leukemia treatment.
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Affiliation(s)
- Natasa Karas-Kuzelicki
- Faculty of pharmacy, University of Ljubljana, Slovenia, Askerceva 7, 1000 Ljubljana, Slovenia
| | - Irena Mlinaric-Rascan
- Faculty of pharmacy, University of Ljubljana, Slovenia, Askerceva 7, 1000 Ljubljana, Slovenia
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226
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Reytor E, Pérez-Miguelsanz J, Alvarez L, Pérez-Sala D, Pajares MA. Conformational signals in the C-terminal domain of methionine adenosyltransferase I/III determine its nucleocytoplasmic distribution. FASEB J 2009; 23:3347-60. [PMID: 19497982 DOI: 10.1096/fj.09-130187] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The methyl donor S-adenosylmethionine is synthesized in mammalian cytosol by three isoenzymes. Methionine adenosyltransferase II is ubiquitously expressed, whereas isoenzymes I (homotetramer) and III (homodimer) are considered the hepatic enzymes. In this work, we identified methionine adenosyltransferase I/III in most rat tissues, both in the cytoplasm and the nucleus. Nuclear localization was the preferred distribution observed in extrahepatic tissues, where the protein colocalizes with nuclear matrix markers. A battery of mutants used in several cell lines to decipher the determinants involved in methionine adenosyltransferase subcellular localization demonstrated, by confocal microscopy and subcellular fractionation, the presence of two partially overlapping areas at the C-terminal end of the protein involved both in cytoplasmic retention and nuclear localization. Immunoprecipitation of coexpressed FLAG and EGFP fusions and gel-filtration chromatography allowed detection of tetramers and monomers in nuclear fractions that also exhibited S-adenosylmethionine synthesis. Neither nuclear localization nor matrix binding required activity, as demonstrated with the inactive F251D mutant. Nuclear accumulation of the active enzyme only correlated with histone H3K27 trimethylation among the epigenetic modifications evaluated, therefore pointing to the necessity of methionine adenosyltransferase I/III to guarantee the supply of S-adenosylmethionine for specific methylations. However, nuclear monomers may exhibit additional roles.
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Affiliation(s)
- Edel Reytor
- Instituto de Investigaciones Biomédicas Alberto Sols (CSIC-UAM), Arturo Duperier 4, 28029 Madrid, Spain
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227
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Kim SJ, Lee JW, Jung YS, Kwon DY, Park HK, Ryu CS, Kim SK, Oh GT, Kim YC. Ethanol-induced liver injury and changes in sulfur amino acid metabolomics in glutathione peroxidase and catalase double knockout mice. J Hepatol 2009; 50:1184-91. [PMID: 19398231 DOI: 10.1016/j.jhep.2009.01.030] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2008] [Revised: 01/07/2009] [Accepted: 01/19/2009] [Indexed: 01/21/2023]
Abstract
BACKGROUND/AIMS Oxidative stress via generation of reactive oxygen species is suggested to be the major mechanism of alcohol-induced liver injury. We investigated the effects of glutathione peroxidase-1 and catalase double deficiency (Gpx-1(-/-)/Cat(-/-)) on liver injury and changes in the sulfur amino acid metabolism induced by binge ethanol administration. METHODS Ethanol (5 g/kg) was administered orally to the wild-type and the Gpx-1(-/-)/Cat(-/-) mice every 12 h for a total of three doses. Mice were sacrificed 6 h after the final dose. RESULTS The Gpx-1/Cat deficiency alone increased malondialdehyde levels in liver significantly. Hepatic methionine adenosyltransferase (MAT) activity and S-adenosylmethionine levels were decreased, however, glutathione contents were not changed. Ethanol administration to the Gpx-1(-/-)/Cat(-/-) mice increased the elevation of serum alanine aminotransferase activity, plasma homocysteine levels, hepatic fat accumulation and lipid peroxidation compared with the wild-type animals challenged with ethanol. Also the reduction of MAT activity and S-adenosylmethionine levels was enhanced, but MATI/III expression was increased significantly. CONCLUSIONS The results indicate that Gpx-1 and Cat have critical roles in the protection of liver against binge ethanol exposure. Augmentation of ethanol-induced oxidative stress may be responsible for the impairment of the transsulfuration reactions and the aggravation of acute liver injury in the Gpx-1(-/-)/Cat(-/-) mice.
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Affiliation(s)
- Sun J Kim
- College of Pharmacy, Seoul National University, San 56-1 Shinrim-Dong, Kwanak-Ku, Seoul 151-742, South Korea
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228
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Matthews RP, Lorent K, Mañoral-Mobias R, Huang Y, Gong W, Murray IVJ, Blair IA, Pack M. TNFalpha-dependent hepatic steatosis and liver degeneration caused by mutation of zebrafish S-adenosylhomocysteine hydrolase. Development 2009; 136:865-75. [PMID: 19201949 DOI: 10.1242/dev.027565] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Hepatic steatosis and liver degeneration are prominent features of the zebrafish ducttrip (dtp) mutant phenotype. Positional cloning identified a causative mutation in the gene encoding S-adenosylhomocysteine hydrolase (Ahcy). Reduced Ahcy activity in dtp mutants led to elevated levels of S-adenosylhomocysteine (SAH) and, to a lesser degree, of its metabolic precursor S-adenosylmethionine (SAM). Elevated SAH in dtp larvae was associated with mitochondrial defects and increased expression of tnfa and pparg, an ortholog of the mammalian lipogenic gene. Antisense knockdown of tnfa rescued hepatic steatosis and liver degeneration in dtp larvae, whereas the overexpression of tnfa and the hepatic phenotype were unchanged in dtp larvae reared under germ-free conditions. These data identify an essential role for tnfa in the mutant phenotype and suggest a direct link between SAH-induced methylation defects and TNF expression in human liver disorders associated with elevated TNFalpha. Although heterozygous dtp larvae had no discernible phenotype, hepatic steatosis was present in heterozygous adult dtp fish and in wild-type adult fish treated with an Ahcy inhibitor. These data argue that AHCY polymorphisms and AHCY inhibitors, which have shown promise in treating autoimmunity and other disorders, may be a risk factor for steatosis, particularly in patients with diabetes, obesity and liver disorders such as hepatitis C infection. Supporting this idea, hepatic injury and steatosis have been noted in patients with recently discovered AHCY mutations.
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Affiliation(s)
- Randolph P Matthews
- Division of Gastroenterology, Hepatology, and Nutrition, The Children's Hospital of Philadelphia and Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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229
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Malaguarnera M, Di Rosa M, Nicoletti F, Malaguarnera L. Molecular mechanisms involved in NAFLD progression. J Mol Med (Berl) 2009; 87:679-95. [PMID: 19352614 DOI: 10.1007/s00109-009-0464-1] [Citation(s) in RCA: 208] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 02/26/2009] [Accepted: 03/18/2009] [Indexed: 02/06/2023]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is an emerging metabolic-related disorder characterized by fatty infiltration of the liver in the absence of alcohol consumption. NAFLD ranges from simple steatosis to non-alcoholic steatohepatitis (NASH), which might progress to end-stage liver disease. This progression is related to the insulin resistance, which is strongly linked to the metabolic syndrome consisting of central obesity, diabetes mellitus, and hypertension. Earlier, the increased concentration of intracellular fatty acids within hepatocytes leads to steatosis. Subsequently, multifactorial complex interactions between nutritional factors, lifestyle, and genetic determinants promote necrosis, inflammation, fibrosis, and hepatocellular damage. Up to now, many studies have revealed the mechanism associated with insulin resistance, whereas the mechanisms related to the molecular components have been incompletely characterized. This review aims to assess the potential molecular mediators initiating and supporting the progression of NASH to establish precocious diagnosis and to plan more specific treatment for this disease.
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230
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Llacuna L, Marí M, Lluis JM, García-Ruiz C, Fernández-Checa JC, Morales A. Reactive oxygen species mediate liver injury through parenchymal nuclear factor-kappaB inactivation in prolonged ischemia/reperfusion. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 174:1776-85. [PMID: 19349371 DOI: 10.2353/ajpath.2009.080857] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Nuclear factor (NF)-kappaB participates in ischemia/reperfusion (I/R) hepatic signaling, stimulating both protective mechanisms and the generation of inflammatory cytokines. After analyzing NF-kappaB activation during increasing times of ischemia in murine I/R, we observed that the nuclear translocation of p65 paralleled Src and IkappaB tyrosine phosphorylation, which peaked after 60 minutes of ischemia. After extended ischemic periods (90 to 120 minutes) however, nuclear p65 levels were inversely correlated with the progressive induction of oxidative stress. Despite this profile of NF-kappaB activation, inflammatory genes, such as tumor necrosis factor (TNF) and interleukin (IL)-1beta, predominantly induced by Kupffer cells, increased throughout time during ischemia (30 to 120 minutes), whereas protective NF-kappaB-dependent genes, such as manganese superoxide dismutase (Mn-SOD), expressed in parenchymal cells, decreased. Consistent with this behavior, gadolinium chloride pretreatment abolished TNF/IL-1beta up-regulation during ischemia without affecting Mn-SOD levels. Interestingly, specific glutathione (GSH) up-regulation in hepatocytes by S-adenosylmethionine increased Mn-SOD expression and protected against I/R-mediated liver injury despite TNF/IL-1beta induction. Similar protection was achieved by administration of the SOD mimetic MnTBAP. In contrast, indiscriminate hepatic GSH depletion by buthionine-sulfoximine before I/R potentiated oxidative stress and decreased both nuclear p65 and Mn-SOD expression levels, increasing TNF/IL-1beta up-regulation and I/R-induced liver damage. Thus, the divergent role of NF-kappaB activation in selective liver cell populations underlies the dichotomy of NF-kappaB in hepatic I/R injury, illustrating the relevance of specifically maintaining NF-kappaB activation in parenchymal cells.
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Affiliation(s)
- Laura Llacuna
- Liver Unit, Hospital Clinic, Institut de Investigacions Biomèdiques August Pi-Sunyer, Centro de Investigaciones Biomédicas Esther Koplowitz, Universitat de Barcelona, Barcelona, Spain
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231
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Ding W, Mouzaki M, You H, Laird JC, Mato J, Lu SC, Rountree CB. CD133+ liver cancer stem cells from methionine adenosyl transferase 1A-deficient mice demonstrate resistance to transforming growth factor (TGF)-beta-induced apoptosis. Hepatology 2009; 49:1277-86. [PMID: 19115422 PMCID: PMC2853874 DOI: 10.1002/hep.22743] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
UNLABELLED Methionine adenosyltransferase (MAT) is an essential enzyme required for S-adenosylmethionine biosynthesis. Hepatic MAT activity falls during chronic liver injury, and mice lacking Mat1a develop spontaneous hepatocellular carcinoma by 18 months. We have previously demonstrated that CD133(+)CD45(-) oval cells isolated from 16-month-old Mat1a(-/-) mice represent a liver cancer stem cell population. The transforming growth factor beta (TGF-beta) pathway constitutes a central signaling network in proliferation, apoptosis, and tumorigenesis. In this study, we tested the response of tumorigenic liver stem cells to TGF-beta. CD133(+)CD45(-) oval cells were isolated from premalignant 16-month-old Mat1a(-/-) mice by flow cytometry and expanded as five clone lines derived from a single cell. All clone lines demonstrated expression of both hepatocyte and cholangiocyte markers and maintained a small population (0.5% to 2%) of CD133(+) cells in vitro, and three of five clone lines produced tumors. Although TGF-beta1 inhibited cell growth equally in CD133(-) and CD133(+) cells from each clone line, the CD133(+) population demonstrated significant resistance to TGF-beta-induced apoptosis compared with CD133(-) cells. Furthermore, CD133(+) cells demonstrated a substantial increase in mitogen-activated protein kinase (MAPK) pathway activation, as demonstrated by phosphorylated extracellular signal-regulated kinase levels before and after TGF-beta stimulation. MAPK inhibition using mitogen-activated protein kinase kinase 1 (MEK1) inhibitor PD98059 led to a significant increase in TGF-beta-induced apoptosis in CD133(+) cells. Conversely, a constitutively active form of MEK1 blocked the apoptotic effects of TGF-beta in CD133(-) cells. CONCLUSION CD133(+) liver cancer stem cells exhibit relative resistance to TGF-beta-induced apoptosis. One mechanism of resistance to TGF-beta-induced apoptosis in CD133(+) cancer stem cells is an activated mitogen-activated protein kinase/extracellular signal-regulated kinase pathway.
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Affiliation(s)
- Wei Ding
- Department of Pediatrics, The Pennsylvania State University College of Medicine, Penn State Children’s Hospital, Hershey, PA,Department of Pharmacology, The Pennsylvania State University College of Medicine, Penn State Children’s Hospital, Hershey, PA
| | - Marialena Mouzaki
- Department of Pediatrics, The Pennsylvania State University College of Medicine, Penn State Children’s Hospital, Hershey, PA,Department of Pharmacology, The Pennsylvania State University College of Medicine, Penn State Children’s Hospital, Hershey, PA
| | - Hanning You
- Department of Pediatrics, The Pennsylvania State University College of Medicine, Penn State Children’s Hospital, Hershey, PA,Department of Pharmacology, The Pennsylvania State University College of Medicine, Penn State Children’s Hospital, Hershey, PA
| | - Joshua C. Laird
- Department of Pediatrics, The Pennsylvania State University College of Medicine, Penn State Children’s Hospital, Hershey, PA,Department of Pharmacology, The Pennsylvania State University College of Medicine, Penn State Children’s Hospital, Hershey, PA
| | - Jose Mato
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology, Park of Bizkaia, Bizkaia, Spain
| | - Shelly C. Lu
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, USC-UCLA Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - C. Bart Rountree
- Department of Pediatrics, The Pennsylvania State University College of Medicine, Penn State Children’s Hospital, Hershey, PA,Department of Pharmacology, The Pennsylvania State University College of Medicine, Penn State Children’s Hospital, Hershey, PA
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232
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TOMASI MARIALAUDA, IGLESIAS–ARA AINHOA, YANG HEPING, RAMANI KOMAL, FEO FRANCESCO, PASCALE MARIAROSA, MARTÍNEZ–CHANTAR MLUZ, MATO JOSÉM, LU SHELLYC. S-adenosylmethionine regulates apurinic/apyrimidinic endonuclease 1 stability: implication in hepatocarcinogenesis. Gastroenterology 2009; 136:1025-36. [PMID: 18983843 PMCID: PMC3600984 DOI: 10.1053/j.gastro.2008.09.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 09/11/2008] [Accepted: 09/18/2008] [Indexed: 01/12/2023]
Abstract
BACKGROUND & AIMS Genomic instability participates in the pathogenesis of hepatocellular carcinoma (HCC). Apurinic/apyrimidinic endonuclease 1 (APEX1) participates in the base excision repair of premutagenic apurinic/apyrimidinic (AP) sites. Mice deficient in methionine adenosyltransferase 1a (Mat1a KO) have chronic hepatic deficiency of S-adenosylmethionine (SAMe) and increased oxidative stress, and develop HCC. We examined livers of Mat1a KO mice for genomic instability and dysregulation of APEX1. METHODS Studies were conducted using Mat1a KO mice livers and cultured mouse and human hepatocytes. RESULTS Genomic instability increased in the livers of 1-month-old Mat1a KO mice, compared with wild-type mice, whereas Apex1 mRNA and protein levels were reduced by 20% and 50%, respectively, in Mat1a KO mice of all ages. These changes correlated with increased numbers of AP sites and reduced expression of Bax, Fas, and p21 (all APEX targets). When human and mouse hepatocytes were placed in culture, transcription of MAT1A mRNA decreased whereas that of APEX1 and c-MYC increased. However, the protein levels of APEX1 decreased to 60% of baseline. Addition of 2 mmol/L SAMe prevented increases in APEX1 and c-MYC mRNA levels, as well as decreases in MAT1A expression and cytosolic and nuclear APEX1 protein levels. CONCLUSIONS By 1 month of age, genomic instability increases in livers of Mat1a KO mice, possibly due to reduced APEX1 levels. Although SAMe inhibits APEX1 transcription, it stabilizes the APEX1 protein. This novel aspect of SAMe on APEX1 regulation might explain the chemopreventive action of SAMe and the reason that chronic SAMe deficiency predisposes to HCC.
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Affiliation(s)
- MARIA LAUDA TOMASI
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, USC-UCLA Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine USC, Los Angeles, California,Department of Biomedical Sciences, Division of Experimental Pathology and Oncology, University of Sassari, Italy
| | - AINHOA IGLESIAS–ARA
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, USC-UCLA Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine USC, Los Angeles, California
| | - HEPING YANG
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, USC-UCLA Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine USC, Los Angeles, California
| | - KOMAL RAMANI
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, USC-UCLA Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine USC, Los Angeles, California
| | - FRANCESCO FEO
- Department of Biomedical Sciences, Division of Experimental Pathology and Oncology, University of Sassari, Italy
| | - MARIA ROSA PASCALE
- Department of Biomedical Sciences, Division of Experimental Pathology and Oncology, University of Sassari, Italy
| | - M. LUZ MARTÍNEZ–CHANTAR
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology, Park of Bizkaia, 48160 Derio, Bizkaia, Spain
| | - JOSÉ M. MATO
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology, Park of Bizkaia, 48160 Derio, Bizkaia, Spain
| | - SHELLY C. LU
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, USC-UCLA Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine USC, Los Angeles, California
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233
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Dever JT, Elfarra AA. Gender differences in methionine accumulation and metabolism in freshly isolated mouse hepatocytes: potential roles in toxicity. Toxicol Appl Pharmacol 2009; 236:358-65. [PMID: 19236888 DOI: 10.1016/j.taap.2009.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 02/10/2009] [Accepted: 02/12/2009] [Indexed: 11/26/2022]
Abstract
L-methionine (Met) is hepatotoxic at high concentrations. Because Met toxicity in freshly isolated mouse hepatocytes is gender-dependent, the goal of this study was to assess the roles of Met accumulation and metabolism in the increased sensitivity of male hepatocytes to Met toxicity compared with female hepatocytes. Male hepatocytes incubated with Met (30 mM) at 37 degrees C exhibited higher levels of intracellular Met at 0.5, 1.0, and 1.5 h, respectively, compared to female hepatocytes. Conversely, female hepatocytes had higher levels of S-adenosyl-L-methionine compared to male hepatocytes. Female hepatocytes also exhibited higher L-methionine-L-sulfoxide levels relative to control hepatocytes, whereas the increases in L-methionine-D-sulfoxide (Met-D-O) levels were similar in hepatocytes of both genders. Addition of aminooxyacetic acid (AOAA), an inhibitor of Met transamination, significantly increased Met levels at 1.5 h and increased Met-d-O levels at 1.0 and 1.5 h only in Met-exposed male hepatocytes. No gender differences in cytosolic Met transamination activity by glutamine transaminase K were detected. However, female mouse liver cytosol exhibited higher methionine-dl-sulfoxide (MetO) reductase activity than male mouse liver cytosol at low (0.25 and 0.5 mM) MetO concentrations. Collectively, these results suggest that increased cellular Met accumulation, decreased Met transmethylation, and increased Met and MetO transamination in male mouse hepatocytes may be contributing to the higher sensitivity of the male mouse hepatocytes to Met toxicity in comparison with female mouse hepatocytes.
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Affiliation(s)
- Joseph T Dever
- Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin, USA
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234
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Vázquez M, Ariz U, Varela-Rey M, Embade N, Martínez N, Fernández D, Gómez L, Lamas S, Lu SC, Martínez-Chantar ML, Mato JM. Evidence for LKB1/AMP-activated protein kinase/ endothelial nitric oxide synthase cascade regulated by hepatocyte growth factor, S-adenosylmethionine, and nitric oxide in hepatocyte proliferation. Hepatology 2009; 49:608-17. [PMID: 19177591 PMCID: PMC2635424 DOI: 10.1002/hep.22660] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
UNLABELLED S-adenosylmethionine (SAMe) is involved in numerous complex hepatic processes such as hepatocyte proliferation, death, inflammatory responses, and antioxidant defense. One of the most relevant actions of SAMe is the inhibition of hepatocyte proliferation during liver regeneration. In hepatocytes, SAMe regulates the levels of cytoplasmic HuR, an RNA-binding protein that increases the half-life of target messenger RNAs such as cyclin D1 and A2 via inhibition of hepatocyte growth factor (HGF)-mediated adenosine monophosphate-activated protein kinase (AMPK) phosphorylation. Because AMPK is activated by the tumor suppressor kinase LKB1, and AMPK activates endothelial nitric oxide (NO) synthase (eNOS), and NO synthesis is of great importance for hepatocyte proliferation, we hypothesized that in hepatocytes HGF may induce the phosphorylation of LKB1, AMPK, and eNOS through a process regulated by SAMe, and that this cascade might be crucial for hepatocyte growth. We demonstrate that the proliferative response of hepatocytes involves eNOS phosphorylation via HGF-mediated LKB1 and AMPK phosphorylation, and that this process is regulated by SAMe and NO. We also show that knockdown of LKB1, AMPK, or eNOS with specific interference RNA (iRNA) inhibits HGF-mediated hepatocyte proliferation. Finally, we found that the LKB1/AMPK/eNOS cascade is activated during liver regeneration after partial hepatectomy and that this process is impaired in mice treated with SAMe before hepatectomy, in knockout mice deficient in hepatic SAMe, and in eNOS knockout mice. CONCLUSION We have identified an LKB1/AMPK/eNOS cascade regulated by HGF, SAMe, and NO that functions as a critical determinant of hepatocyte proliferation during liver regeneration after partial hepatectomy.
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Affiliation(s)
- Mercedes Vázquez
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain,Contributed equally to this paper. MLMC and JMM share senior authorship
| | - Usue Ariz
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain,Contributed equally to this paper. MLMC and JMM share senior authorship
| | - Marta Varela-Rey
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Nieves Embade
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Nuria Martínez
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - David Fernández
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Laura Gómez
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Santiago Lamas
- Centro de Investigaciones Biológicas-CSIC 28040-Madrid, Spain
| | - Shelly C Lu
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University Southern California, Los Angeles, CA 90033
| | - M Luz Martínez-Chantar
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - José M Mato
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
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235
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Wang Q, Liu QY, Liu ZS, Qian Q, Sun Q, Pan DY. Inhibition of hepatocelluar carcinoma MAT2A and MAT2beta gene expressions by single and dual small interfering RNA. J Exp Clin Cancer Res 2008; 27:72. [PMID: 19025580 PMCID: PMC2613873 DOI: 10.1186/1756-9966-27-72] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Accepted: 11/21/2008] [Indexed: 03/02/2023] Open
Abstract
RNA interference (RNAi) has been successfully applied in suppression of hepatic cancer genes. In hepatocelluar carcinoma cell, one methionine adenosyltransferase (MAT) isozyme, MATII was found to have two catalytic subunits which were encoded by MAT2A and MAT2β respectively. During tumorigeness of hepatocelluar carcinoma, expressions of the two genes were discovered to be increased combining with a switch of MAT (form MATI to MATII), To figure out the role played by MATII in hepatic cancer, In this study, for the first time we established a dual small interfering RNA (siRNA) expression system, which could simultaneously express two different siRNA molecules specifically targeting two genes. To test the effectiveness of this system, we applied this approach to express simultaneously two different siRNA duplexes that specifically target MAT2A and MAT2β genes of hepatocelluar carcinoma respectively in HepG2 cell. Results indicated that dual siRNA could simultaneously inhibit the expression of MAT2A and MAT2β gene by 89.5% and 97.8% respectively, In addition, dual siRNA molecules were able to significantly suppress growth of hepatocelluar carcinoma cell in vitro as well as induce apoptosis which was involved in arrest cell cycle at the G1/S checkpoint and the expressions of p21, p27 and Bax.
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Affiliation(s)
- Qun Wang
- Department of General Surgery, Zhongnan Hospital of Wuhan University, Hubei Province, PR China.
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236
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Abstract
SAMe (S-adenosylmethionine) is the main methyl donor group in the cell. MAT (methionine adenosyltransferase) is the unique enzyme responsible for the synthesis of SAMe from methionine and ATP, and SAMe is the common point between the three principal metabolic pathways: polyamines, transmethylation and transsulfuration that converge into the methionine cycle. SAMe is now also considered a key regulator of metabolism, proliferation, differentiation, apoptosis and cell death. Recent results show a new signalling pathway implicated in the proliferation of the hepatocyte, where AMPK (AMP-activated protein kinase) and HuR, modulated by SAMe, take place in HGF (hepatocyte growth factor)-mediated cell growth. Abnormalities in methionine metabolism occur in several animal models of alcoholic liver injury, and it is also altered in patients with liver disease. Both high and low levels of SAMe predispose to liver injury. In this regard, knockout mouse models have been developed for the enzymes responsible for SAMe synthesis and catabolism, MAT1A and GNMT (glycine N-methyltransferase) respectively. These knockout mice develop steatosis and HCC (hepatocellular carcinoma), and both models closely replicate the pathologies of human disease, which makes them extremely useful to elucidate the mechanism underlying liver disease. These new findings open a wide range of possibilities to discover novel targets for clinical applications.
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237
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Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most common cause of referral to liver clinics, and its progressive form, non-alcoholic steatohepatitis (NASH), can lead to cirrhosis and end-stage liver disease. The main risk factors for NAFLD/NASH are the metabolic abnormalities commonly observed in metabolic syndrome: insulin resistance, visceral obesity, dyslipidemia and altered adipokine profile. At present, the causes of progression from NAFLD to NASH remain poorly defined, and research in this area has been limited by the availability of suitable animal models of this disease. In the past, the main models used to investigate the pathogenesis of steatohepatitis have either failed to reproduce the full spectrum of liver pathology that characterizes human NASH, or the liver pathology has developed in a metabolic context that is not representative of the human condition. In the last few years, a number of models have been described in which the full spectrum of liver pathology develops in an appropriate metabolic context. In general, the underlying cause of metabolic defects in these models is chronic caloric overconsumption, also known as overnutrition. Overnutrition has been achieved in a number of different ways, including forced feeding, administration of high-fat diets, the use of genetically hyperphagic animals, or a combination of these approaches. The purpose of the present review is to critique the liver pathology and metabolic abnormalities present in currently available animal models of NASH, with particular focus on models described in approximately the last 5 years.
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Affiliation(s)
- Claire Z Larter
- ANU Medical School, Australian National University at The Canberra Hospital, Canberra, ACT, Australia.
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238
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Zhou W, Alonso S, Takai D, Lu SC, Yamamoto F, Perucho M, Huang S. Requirement of RIZ1 for cancer prevention by methyl-balanced diet. PLoS One 2008; 3:e3390. [PMID: 18852888 PMCID: PMC2559864 DOI: 10.1371/journal.pone.0003390] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Accepted: 09/16/2008] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The typical Western diet is not balanced in methyl nutrients that regulate the level of the methyl donor S-adenosylmethionine (SAM) and its derivative metabolite S-adenosylhomocysteine (SAH), which in turn may control the activity of certain methyltransferases. Feeding rodents with amino acid defined and methyl-imbalanced diet decreases hepatic SAM and causes liver cancers. RIZ1 (PRDM2 or KMT8) is a tumor suppressor and functions in transcriptional repression by methylating histone H3 lysine 9. METHODOLOGY/PRINCIPAL FINDINGS Here we show that a methyl-balanced diet conferred additional survival benefits compared to a tumor-inducing methyl-imbalanced diet only in mice with wild type RIZ1 but not in mice deficient in RIZ1. While absence of RIZ1 was tumorigenic in mice fed the balanced diet, its presence did not prevent tumor formation in mice fed the imbalanced diet. Microarray and gene expression analysis showed that, unlike most of its related enzymes, RIZ1 was upregulated by methyl-balanced diet. Methyl-balanced diet did not fully repress oncogenes such as c-Jun in the absence of RIZ1. Higher RIZ1 activity was associated with greater H3 lysine 9 methylation in RIZ1 target genes as shown by chromatin immunoprecipitation analysis. CONCLUSIONS/SIGNIFICANCE The data identify RIZ1 as a critical target of methyl-balanced diet in cancer prevention. The molecular understanding of dietary carcinogenesis may help people make informed choices on diet, which may greatly reduce the incidence of cancer.
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Affiliation(s)
- Wenyun Zhou
- Cancer Research Center, The Burnham Institute for Medical Research, La Jolla, California, United States of America
| | - Sergio Alonso
- Cancer Research Center, The Burnham Institute for Medical Research, La Jolla, California, United States of America
| | - Daisaku Takai
- Cancer Research Center, The Burnham Institute for Medical Research, La Jolla, California, United States of America
| | - Shelly C. Lu
- Gastrointestinal and Liver Diseases, USC Research Center for Liver Diseases, USC-UCLA Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Fumiichiro Yamamoto
- Cancer Research Center, The Burnham Institute for Medical Research, La Jolla, California, United States of America
| | - Manuel Perucho
- Cancer Research Center, The Burnham Institute for Medical Research, La Jolla, California, United States of America
| | - Shi Huang
- Cancer Research Center, The Burnham Institute for Medical Research, La Jolla, California, United States of America
- Institute of Biomedical Sciences, Center for Evolutionary Biology, Fudan University, Shanghai, China
- * E-mail:
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239
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Abstract
In the early 1930s, Banting and Best, the discoverers of insulin, found that choline could prevent the development of fatty liver disease (steatosis) in pancreatectomized dogs treated with insulin. Later work indicated that in rats and mice, diets deficient in labile methyl groups (choline, methionine, betaine, folate) produced fatty liver and that long-term administration of diets deficient in choline and methionine also caused hepatocellular carcinoma. These experiments not only linked steatosis and diabetes but also provided evidence, for the first time, of the importance of labile methyl group balance to maintain normal liver function. This conclusion is now amply supported by the observation of mice devoid of key enzymes of methionine and folate metabolism and in patients with severe deficiencies in these enzymes. Moreover, treatments with various methionine metabolites in experimental animal models of liver disease show hepatoprotective properties.
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Affiliation(s)
- José M Mato
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (ciberhed), Technology Park of Bizkaia, 48160 Derio, Bizkaia, Spain.
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240
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Temporary consumption of diet with unbalanced amino acid pattern affects long-lasting growth retardation correlated with oxidative stress response associated gene expression in juvenile pigs. Clin Nutr 2008; 27:781-9. [DOI: 10.1016/j.clnu.2008.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 05/20/2008] [Accepted: 06/23/2008] [Indexed: 10/21/2022]
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241
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Abstract
Endotoxemia participates in the pathogenesis of many liver injuries. Lipopolysaccharide (LPS) was shown to inactivate hepatic methionine adenosyltransferase (MAT), the enzyme responsible for S-adenosylmethionine (SAMe) biosynthesis. SAMe treatment was shown to prevent the LPS-induced increase in tumor necrosis factor-alpha, which may be one of its beneficial effects. SAMe is also an important precursor of glutathione (GSH) and GSH was shown to ameliorate LPS-induced hepatotoxicity. The aims of this work were to examine changes in SAMe and GSH homeostasis during endotoxemia and the effect of SAMe. Mice received SAMe or vehicle pretreatment followed by LPS and were killed up to 18 h afterward. Unexpectedly, we found hepatic SAMe level increased 67% following LPS treatment while S-adenosylhomocysteine level fell by 26%, suggesting an increase in SAMe biosynthesis and/or block in transmethylation. The mRNA and protein levels of MAT1A and MAT2A were increased following LPS. However, despite increased MAT1A expression, MAT activity remained inhibited 18 h after LPS. The major methyltransferase that catabolizes hepatic SAMe is glycine N-methyltransferase, whose expression fell by 65% following LPS. Hepatic GSH level fell more than 50% following LPS, coinciding with a comparable fall in the mRNA and protein levels of glutamate-cysteine ligase (GCL) catalytic (GCLC) and modifier subunits (GCLM). SAMe pretreatment prevented the fall in GCLC and attenuated the fall in GCLM expression and GSH level. SAMe pretreatment prevented the LPS-induced increase in plasma alanine transaminases levels but not the LPS-induced increase in hepatic mRNA levels of proinflammatory cytokines. It further enhanced LPS-induced increase in interleukin-10 mRNA level. Taken together, the hepatic response to LPS is to upregulate MAT expression and inhibit SAMe utilization. GSH is markedly depleted largely due to lower expression of GCL. Interestingly, SAMe treatment prevented the fall in GCL and helped to preserve the GSH store and prevent liver injury.
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242
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The transition from fatty liver to NASH associates with SAMe depletion in db/db mice fed a methionine choline-deficient diet. Dig Dis Sci 2008; 53:2761-74. [PMID: 18299981 PMCID: PMC3991247 DOI: 10.1007/s10620-007-0193-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Accepted: 12/21/2007] [Indexed: 12/13/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is highly prevalent in the Western population. By mechanisms that are not completely understood, this disease may progress to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). db/db mice spontaneously develop hepatic steatosis, which progresses to NASH when these mice are fed a methionine choline-deficient (MCD) diet. The goal of our studies was to identify lipid and methionine metabolism pathways affected by MCD feeding to determine potential causal events leading to the development of NASH from benign steatosis. db/db mice fed the MCD diet for 2 weeks exhibited signs of incipient NASH development such as upregulated cytokines and chemokines. At this time point, MCD diet feeding caused S-adenosylmethionine (SAMe) depletion in db/db mice, while wild-type mice on the same diet retained hepatic SAMe levels. SAMe depletion exerts pleiotropic effects upon liver homeostasis and is commonly associated with a variety of liver insults such as thioacetamide, CCL4, and alcohol treatment; thus, SAMe depletion may serve as the second hit in NASH development. It is possible that differences in hepatic lipid and/or methionine metabolism between wild-type and db/db mice underlay the differential maintenance of SAMe levels during methionine and choline restriction. Indeed, db/db mice exhibited inhibited lipid oxidation pathways, which may be a priming factor for NASH development, and db/db mice fed the MCD diet had differential methionine adenosyltransferase (MAT) expression. The occurrence of SAMe depletion at this early, benign stage of NASH development in db/db mice with fatty liver suggests that SAMe supplementation may be (A) targeted to individuals susceptible to NASH (i.e., NAFLD patients) and (B) preventative of NASH before substantial liver injury has occurred.
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243
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Wang Q, Liu QY, Liu ZS, Qian Q, Sun Q, Pan DY. Lentivirus mediated shRNA interference targeting MAT2B induces growth-inhibition and apoptosis in hepatocellular carcinoma. World J Gastroenterol 2008; 14:4633-42. [PMID: 18698677 PMCID: PMC2738787 DOI: 10.3748/wjg.14.4633] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [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 effects of lentivirus vector mediated short hairpin RNA interference targeting methionine adenosyltransferase 2β gene (LV-shMAT2B) on hepatocellular carcinoma (HCC) cells.
METHODS: We constructed four plasmids of RNA interference targeting the MAT2B gene. After LV-shMAT2B was transfected with L-02 cells and two kinds of HCC cells, cell viability and proliferation were measured with MTT and [3H]thymidine assays respectively. Flow cytometry was used to assess cell apoptosis. The level of S-adenosyl methionine (SAMe) in HepG2 cells was evaluated. The expressions of cyclin D1, cyclin D2, bcl-xL and bcl-xS were detected with western blot.
RESULTS: We constructed LV-shMAT2B successfully. LV-shMAT2B was safe for human normal liver cells. LV-shMAT2B caused dramatic reduction in proliferation compared with controls in HCC cells Bel-7402 (P = 0.054) and HepG2 (P = 0.031). Flow cytometry analysis showed that cell apoptosis caused by LV-shMAT2B was greater in HCC cells Bel-7402 and HepG2 than in control induced by scrambled siRNA (P = 0.047), but apoptosis rates in L-02 induced by LV-shMAT2B and scrambled siRNA respectively had no significant difference. Moreover, LV-shMAT2B significantly suppressed expression of MAT2B leading to growth-inhibition effect on HCC cells by down-regulating cyclin D1. Apoptosis induced by LV-shMAT2B was involved in down-regulating bcl-xL and up- regulating bcl-xS.
CONCLUSION: LV-shMAT2B can induce cell apoptosis and growth-inhibition in HCC cells. MAT2B may be a therapy target in HCC in the future.
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244
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Wagner EJ, Krugner-Higby L, Heath TD. Liposome dependent delivery of S-adenosyl methionine to cells by liposomes: a potential treatment for liver disease. J Pharm Sci 2008; 98:573-82. [PMID: 18642386 DOI: 10.1002/jps.21460] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The present study demonstrates that the nutritional supplement S-adenosyl methionine (SAMe), the primary methyl donor in mammalian cells, is delivered selectively to cells by anionic liposomes, and is, therefore, a liposome dependent drug. Contrary to our expectations, free SAMe chloride was growth inhibitory in cultured cells. The growth inhibitory potency of SAMe chloride in anionic liposomes composed of distearoylphosphatidylglycerol/cholesterol 2:1 was fivefold greater than that of free SAMe. Neutral liposomes composed of distearoylphosphatidylcholine and cholesterol did not increase the potency of the drug. An improved anionic liposome SAMe formulation was produced by use of the 1,4-butanedisulfonate salt (SD4), adding a metal chelator (EDTA), and lowering the buffer pH from pH 7.0 to pH 4.0. This formulation was 15-fold more potent than free SD4, and was active after more than 28 days at 4 degrees C. SAMe and its potential degradation products were screened for toxicity. Formaldehyde was determined to have potency similar to that of free SAMe chloride in CV1-P cells, suggesting that the growth inhibitory effects of SAMe may partly arise from the formation of formaldehyde. The cytotoxic effects of formaldehyde and the less stable forms of SAMe, (SAMe chloride and SAMe tosylate) were decreased in the presence of 3 mM GSH (IC(50) approximately 0.44 mM). The cytotoxic effects of SD4 were not reduced by GSH, suggesting that this more stable form of SAMe is not toxic through the production of formaldehyde. SD4 in anionic DSPG liposomes stimulated murine IL-6 production in RAW 264 cells at concentrations 25- to 30-fold lower than free drug. This increase in potency for IL-6 production was in keeping with the increase in potency observed in our growth inhibition experiments. These results suggest that SD4 in liposomes may be a potential treatment for acute or chronic liver failure.
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Affiliation(s)
- Eric J Wagner
- Schools of Pharmacy and Veterinary Medicine, University of Wisconsin Madison, Madison, Wisconsin 53705-222, USA
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245
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Dever JT, Elfarra AA. L-methionine toxicity in freshly isolated mouse hepatocytes is gender-dependent and mediated in part by transamination. J Pharmacol Exp Ther 2008; 326:809-17. [PMID: 18552130 DOI: 10.1124/jpet.108.141044] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
L-methionine (Met) has been implicated in parenteral nutrition-associated cholestasis in infants and, at high levels, it causes liver toxicity by mechanisms that are not clear. In this study, Met toxicity was characterized in freshly isolated male and female mouse hepatocytes incubated with 5 to 30 mM Met for 0 to 5 h. In male hepatocytes, 20 mM Met was cytotoxic at 4 h as indicated by trypan blue exclusion and lactate dehydrogenase leakage assays. Cytotoxicity was preceded by reduced glutathione (GSH) depletion at 3 h without glutathione disulfide formation. Exposure to 30 mM Met resulted in increased cytotoxicity and GSH depletion. It is interesting to note that female hepatocytes were resistant to Met-induced cytotoxicity at these concentrations and showed increased cellular GSH levels compared with hepatocytes exposed to medium alone. The effects of amino-oxyacetic acid (AOAA), an inhibitor of Met transamination, and 3-deazaadenosine (3-DA), an inhibitor of the Met transmethylation pathway enzyme S-adenosylhomocysteine hydrolase, on Met toxicity in male hepatocytes were then examined. Addition of 0.2 mM AOAA partially blocked Met-induced GSH depletion and cytotoxicity, whereas 0.1 mM 3-DA potentiated Met-induced toxicity. Exposure of male hepatocytes to 0.3 mM 3-methylthiopropionic acid (3-MTP), a known Met transamination metabolite, resulted in cytotoxicity and cellular GSH depletion similar to that observed with 30 mM Met, whereas incubations with D-methionine resulted in no toxicity. Female hepatocytes were less sensitive to 3-MTP toxicity than males, which may partially explain their resistance to Met toxicity. Taken together, these results suggest that Met transamination and not transmethylation plays a major role in Met toxicity in male mouse hepatocytes.
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Affiliation(s)
- Joseph T Dever
- Department of Comparative Biosciences and Molecular and Environmental Toxicology Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
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246
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Cave MC, Hurt RT, Frazier TH, Matheson PJ, Garrison RN, McClain CJ, McClave SA. Obesity, inflammation, and the potential application of pharmaconutrition. Nutr Clin Pract 2008; 23:16-34. [PMID: 18203961 DOI: 10.1177/011542650802300116] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Obesity is an emerging problem worldwide. Hospitalized obese patients often have a worse outcome than patients of normal weight, particularly in the setting of trauma and critical care. Obesity creates a low-grade systemic inflammatory response syndrome (SIRS) that is similar (but on a much smaller scale) to gram-negative sepsis. This process involves up-regulation of systemic immunity, is characterized clinically by insulin resistance and the metabolic syndrome, and puts the patient at increased risk for organ failure, infectious morbidity, and mortality. Through lipotoxicity and cytokine dysregulation, obesity may act to prime the immune system, predisposing to an exaggerated subsequent immune response when a second clinical insult occurs (such as trauma, burns, or myocardial infarction). Specialized nutrition therapy for such patients currently consists of a hypocaloric, high-protein diet. However, this approach does not address the putative pathophysiologic mechanisms of inflammation and altered metabolism associated with obesity. A number of dietary agents such as arginine, fish oil, and carnitine may correct these problems at the molecular level. Pharmaconutrition formulas may provide exciting innovations for the nutrition therapy of the obese patient.
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Affiliation(s)
- Matt C Cave
- Department of Medicine, University of Louisville School of Medicine, 500 S. Jackson Street, University of Louisville, Louisville, KY 40292, USA
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247
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Bart Rountree C, Senadheera S, Mato JM, Crooks GM, Lu SC. Expansion of liver cancer stem cells during aging in methionine adenosyltransferase 1A-deficient mice. Hepatology 2008; 47:1288-97. [PMID: 18167064 PMCID: PMC2408692 DOI: 10.1002/hep.22141] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UNLABELLED Methionine adenosyltransferase (MAT) is an essential enzyme that catalyzes the biosynthesis of S-adenosylmethionine. Hepatic MAT activity falls in chronic liver diseases, and mice lacking Mat1a are predisposed to liver injury and develop hepatocellular carcinoma (HCC) spontaneously by 18 months. The current work examined the hypothesis that liver cancer stem cells contribute to HCC in this model. Livers from 6- and 18-month-old Mat1a-knockout (KO) mice and their wild-type (WT) littermates were fractionated and isolated by flow cytometry. CD45- nonparenchymal (NP) cells were cultured using liver stem cell conditions. Cells were analyzed by real-time PCR and fluorescent immunohistochemistry (FIHC). Tumor formation was assessed by injecting 1 x 10(6) CD133+CD49f+ cells intraperitoneally into immune-deficient mice. The proportion of CD49f+ and CD133+ cells in the CD45-NP fraction increased 4.5- to 5.5-fold from 6 to 18 months in KO mice but not in their WT littermates. Compared to CD49f- cells from old KO mice, CD49f+ cells from the same animals had a markedly increased expression of several oncogenes. CD133+ cells with CD49f coexpression were selected in vitro and exhibited rapid growth, with the expression of biliary cytokeratins, alpha-fetoprotein, and c-Met by FIHC. Clonal expansion of single CD133+CD49f+ cells revealed maintenance of bipotency. After CD133+CD49f+ cells were injected into immune-deficient mice, 3 of the 8 mice developed tumors of liver epithelial cells after 6-8 weeks. CONCLUSION Mat1a(-/-) mice have expansion of liver stem cells as they age. These cells have increased expression of several oncogenes and are tumorigenic in vivo. This is the first demonstration of adult liver stem cells possessing tumorigenic potential without the use of a carcinogen or manipulation of tumor-suppressor or oncogene expression.
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Affiliation(s)
- C. Bart Rountree
- Division of Gastroenterology, Children’s Hospital, Los Angeles, Los Angeles, CA,Gene, Immunology, and Stem Cell Program, Children’s Hospital, Los Angeles, Los Angeles, CA,Division of Pediatric Gastroenterology, Penn State Children’s Hospital, Hershey, PA,Address reprints to: C. Bart Rountree, M.D., Division of Pediatric Gastroenterology, Penn State Children’s Hospital, H0850, 500 University Drive, P.O. Box 850, Hershey, PA 17033-0850. E-mail: ; fax: 717-531-0653; Shelly C. Lu, M.D., Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, USC, HMR 415, 2011 Zonal Avenue, Los Angeles, CA 90033. E-mail: ; fax: 323-442-3234
| | - Shantha Senadheera
- Gene, Immunology, and Stem Cell Program, Children’s Hospital, Los Angeles, Los Angeles, CA
| | - Jose M. Mato
- CIC bioGUNE, CIBERehd, Technology Park of Bizkaia, Bizkaia, Spain
| | - Gay M. Crooks
- Gene, Immunology, and Stem Cell Program, Children’s Hospital, Los Angeles, Los Angeles, CA
| | - Shelly C. Lu
- Division of Gastrointestinal and Liver Diseases, USC Research Center for Liver Diseases, USC-UCLA Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine, USC, Los Angeles, CA,Address reprints to: C. Bart Rountree, M.D., Division of Pediatric Gastroenterology, Penn State Children’s Hospital, H0850, 500 University Drive, P.O. Box 850, Hershey, PA 17033-0850. E-mail: ; fax: 717-531-0653; Shelly C. Lu, M.D., Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, USC, HMR 415, 2011 Zonal Avenue, Los Angeles, CA 90033. E-mail: ; fax: 323-442-3234
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Luz Martínez-Chantar M, Vázquez-Chantada M, Ariz U, Martínez N, Varela M, Luka Z, Capdevila A, Rodríguez J, Aransay AM, Matthiesen R, Yang H, Calvisi DF, Esteller M, Fraga M, Lu SC, Wagner C, Mato JM. Loss of the glycine N-methyltransferase gene leads to steatosis and hepatocellular carcinoma in mice. Hepatology 2008; 47:1191-9. [PMID: 18318442 PMCID: PMC2405897 DOI: 10.1002/hep.22159] [Citation(s) in RCA: 236] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UNLABELLED Glycine N-methyltransferase (GNMT) is the main enzyme responsible for catabolism of excess hepatic S-adenosylmethionine (SAMe). GNMT is absent in hepatocellular carcinoma (HCC), messenger RNA (mRNA) levels are significantly lower in livers of patients at risk of developing HCC, and GNMT has been proposed to be a tumor-susceptibility gene for liver cancer. The identification of several children with liver disease as having mutations of the GNMT gene further suggests that this enzyme plays an important role in liver function. In the current study we studied development of liver pathologies including HCC in GNMT-knockout (GNMT-KO) mice. GNMT-KO mice have elevated serum aminotransferase, methionine, and SAMe levels and develop liver steatosis, fibrosis, and HCC. We found that activation of the Ras and Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathways was increased in liver tumors from GNMT-KO mice coincidently with the suppression of the Ras inhibitors Ras-association domain family/tumor suppressor (RASSF) 1 and 4 and the JAK/STAT inhibitors suppressor of cytokine signaling (SOCS) 1-3 and cytokine-inducible SH2-protein. Finally, we found that methylation of RASSF1 and SOCS2 promoters and the binding of trimethylated lysine 27 in histone 3 to these 2 genes was increased in HCC from GNMT-KO mice. CONCLUSION These data demonstrate that loss of GNMT induces aberrant methylation of DNA and histones, resulting in epigenetic modulation of critical carcinogenic pathways in mice.
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Affiliation(s)
| | | | - Usue Ariz
- CIC bioGUNE, CIBERehd, Technology Park of Bizkaia, Bizkaia, Spain
| | - Nuria Martínez
- CIC bioGUNE, CIBERehd, Technology Park of Bizkaia, Bizkaia, Spain
| | - Marta Varela
- CIC bioGUNE, CIBERehd, Technology Park of Bizkaia, Bizkaia, Spain
| | - Zigmund Luka
- Department of Biochemistry, Vanderbilt University, Nashville, TN
| | | | - Juan Rodríguez
- CIC bioGUNE, CIBERehd, Technology Park of Bizkaia, Bizkaia, Spain
| | - Ana M. Aransay
- CIC bioGUNE, CIBERehd, Technology Park of Bizkaia, Bizkaia, Spain
| | - Rune Matthiesen
- CIC bioGUNE, CIBERehd, Technology Park of Bizkaia, Bizkaia, Spain
| | - Heping Yang
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University Southern California, Los Angeles, CA
| | - Diego F. Calvisi
- Division of Experimental Pathology and Oncology, University of Sassary, Sassary, Italy
| | - Manel Esteller
- Centro Nacional de Investigaciones Oncológicas, Madrid, Spain
| | - Mario Fraga
- Centro Nacional de Investigaciones Oncológicas, Madrid, Spain
| | - Shelly C. Lu
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University Southern California, Los Angeles, CA
| | - Conrad Wagner
- Department of Biochemistry, Vanderbilt University, Nashville, TN,Tennessee Valley Department of Medical Affairs Medical Center, Nashville, TN
| | - José M. Mato
- CIC bioGUNE, CIBERehd, Technology Park of Bizkaia, Bizkaia, Spain
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249
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Mantena SK, King AL, Andringa KK, Eccleston HB, Bailey SM. Mitochondrial dysfunction and oxidative stress in the pathogenesis of alcohol- and obesity-induced fatty liver diseases. Free Radic Biol Med 2008; 44:1259-72. [PMID: 18242193 PMCID: PMC2323912 DOI: 10.1016/j.freeradbiomed.2007.12.029] [Citation(s) in RCA: 333] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 12/19/2007] [Accepted: 12/19/2007] [Indexed: 12/16/2022]
Abstract
Fatty liver disease associated with chronic alcohol consumption or obesity/type 2 diabetes has emerged as a serious public health problem. Steatosis, accumulation of triglyceride in hepatocytes, is now recognized as a critical "first-hit" in the pathogenesis of liver disease. It is proposed that steatosis "primes" the liver to progress to more severe liver pathologies when individuals are exposed to subsequent metabolic and/or environmental stressors or "second-hits." Genetic risk factors can also influence the susceptibility to and severity of fatty liver disease. Furthermore, oxidative stress, disrupted nitric oxide (NO) signaling, and mitochondrial dysfunction are proposed to be key molecular events that accelerate or worsen steatosis and initiate progression to steatohepatitis and fibrosis. This review article will discuss the following topics regarding the pathobiology and molecular mechanisms responsible for fatty liver disease: (1) the "two-hit" or "multi-hit" hypothesis, (2) the role of mitochondrial bioenergetic defects and oxidant stress, (3) the interplay between NO and mitochondria in fatty liver disease, (4) genetic risk factors and oxidative stress-responsive genes, and (5) the feasibility of antioxidants for treatment.
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Affiliation(s)
| | | | | | | | - Shannon M. Bailey
- *Corresponding Author: Shannon M. Bailey, PhD, Associate Professor, Department of Environmental Health Sciences, Center for Free Radical Biology, University of Alabama at Birmingham, Ryals Building, Room 623, 1530 3 Avenue South, Birmingham, AL 35294 USA, Phone: 205-934-7070, Fax: 205-975-6341,
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250
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Abstract
S-Adenosylmethionine (SAMe), the principal biological methyl donor, is synthesized from methionine and ATP in a reaction catalyzed by methionine adenosyltransferase (MAT). In mammals, two genes (MAT1A and MAT2A), encode for two homologous MAT catalytic subunits, while a third gene MAT2beta, encodes for the beta-subunit that regulates MAT2A-encoded isoenzyme. Normal liver expresses MAT1A, whereas extrahepatic tissues express MAT2A. MAT2A and MAT2 beta are induced in human hepatocellular carcinoma (HCC), which facilitate cancer cell growth. Patients with cirrhosis of various etiologies, including alcohol, have decreased hepatic MAT activity and SAMe biosynthesis. Consequences of hepatic SAMe deficiency as illustrated by the Mat1a knock-out mouse model include increased susceptibility to steatosis and oxidative liver injury, spontaneous development of steatohepatitis and HCC. Predisposition to HCC can be partly explained by the effect of SAMe on growth. Thus, SAMe inhibits the mitogenic effect of growth factors such as hepatocyte growth factor and, following partial hepatectomy, a fall in SAMe level is required for the liver to regenerate. During liver regeneration, the fall in hepatic SAMe is transient. If the fall were to persist, it would favor a proliferative phenotype and, ultimately, development of HCC. Not only does SAMe control liver growth, it also regulates apoptosis. Interestingly, SAMe is anti-apoptotic in normal hepatocytes but pro-apoptotic in liver cancer cells. In liver cancer cells but not in normal human hepatocytes, SAMe can selectively induce Bcl-x(S), an alternatively spliced isoform of Bcl-x(L) that promotes apoptosis. This should make SAMe an attractive agent for both chemoprevention and treatment of HCC.
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Affiliation(s)
- Shelly C Lu
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, USC-UCLA Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine USC, Los Angeles, California, USA
| | - José M Mato
- CIC bioGUNE, Ciberehd, Technology Park of Bizkaia, Bizkaia, Spain
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