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Martínez-Uña M, Varela-Rey M, Cano A, Fernández-Ares L, Beraza N, Aurrekoetxea I, Martínez-Arranz I, García-Rodríguez JL, Buqué X, Mestre D, Luka Z, Wagner C, Alonso C, Finnell RH, Lu SC, Martínez-Chantar ML, Aspichueta P, Mato JM. Excess S-adenosylmethionine reroutes phosphatidylethanolamine towards phosphatidylcholine and triglyceride synthesis. Hepatology 2013; 58:1296-305. [PMID: 23505042 PMCID: PMC3720726 DOI: 10.1002/hep.26399] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 03/10/2013] [Indexed: 01/10/2023]
Abstract
UNLABELLED Methionine adenosyltransferase 1A (MAT1A) and glycine N-methyltransferase (GNMT) are the primary genes involved in hepatic S-adenosylmethionine (SAMe) synthesis and degradation, respectively. Mat1a ablation in mice induces a decrease in hepatic SAMe, activation of lipogenesis, inhibition of triglyceride (TG) release, and steatosis. Gnmt-deficient mice, despite showing a large increase in hepatic SAMe, also develop steatosis. We hypothesized that as an adaptive response to hepatic SAMe accumulation, phosphatidylcholine (PC) synthesis by way of the phosphatidylethanolamine (PE) N-methyltransferase (PEMT) pathway is stimulated in Gnmt(-/-) mice. We also propose that the excess PC thus generated is catabolized, leading to TG synthesis and steatosis by way of diglyceride (DG) generation. We observed that Gnmt(-/-) mice present with normal hepatic lipogenesis and increased TG release. We also observed that the flux from PE to PC is stimulated in the liver of Gnmt(-/-) mice and that this results in a reduction in PE content and a marked increase in DG and TG. Conversely, reduction of hepatic SAMe following the administration of a methionine-deficient diet reverted the flux from PE to PC of Gnmt(-/-) mice to that of wildtype animals and normalized DG and TG content preventing the development of steatosis. Gnmt(-/-) mice with an additional deletion of perilipin2, the predominant lipid droplet protein, maintain high SAMe levels, with a concurrent increased flux from PE to PC, but do not develop liver steatosis. CONCLUSION These findings indicate that excess SAMe reroutes PE towards PC and TG synthesis and lipid sequestration.
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Affiliation(s)
- Maite Martínez-Uña
- Department of Physiology, University of the Basque Country UPV/EHU, Medical School, Bilbao, Spain
| | - Marta Varela-Rey
- CIC bioGUNE, Ciberehd, Parque Tecnológico de Bizkaia, Bizkaia, Spain
| | | | - Larraitz Fernández-Ares
- Department of Physiology, University of the Basque Country UPV/EHU, Medical School, Bilbao, Spain
| | - Naiara Beraza
- CIC bioGUNE, Ciberehd, Parque Tecnológico de Bizkaia, Bizkaia, Spain
| | - Igor Aurrekoetxea
- Department of Physiology, University of the Basque Country UPV/EHU, Medical School, Bilbao, Spain
| | | | | | - Xabier Buqué
- Department of Physiology, University of the Basque Country UPV/EHU, Medical School, Bilbao, Spain
| | - Daniela Mestre
- Department of Physiology, University of the Basque Country UPV/EHU, Medical School, Bilbao, Spain
| | - Zigmund Luka
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennesse
| | - Conrad Wagner
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennesse
| | | | - Richard H Finnell
- Department of Nutritional Sciences, Dell Pediatric Institute, The University of Texas at Austin, Austin, Texas
| | - 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 USC, Los Angeles, California
| | | | - Patricia Aspichueta
- Department of Physiology, University of the Basque Country UPV/EHU, Medical School, Bilbao, Spain
| | - José M Mato
- CIC bioGUNE, Ciberehd, Parque Tecnológico de Bizkaia, Bizkaia, Spain
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152
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Epigenetic regulation of hepatocellular carcinoma in non-alcoholic fatty liver disease. Semin Cancer Biol 2013; 23:471-82. [PMID: 24018165 DOI: 10.1016/j.semcancer.2013.08.010] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 08/30/2013] [Indexed: 02/07/2023]
Abstract
Emerging evidence that epigenetics converts alterations in nutrient and metabolism into heritable pattern of gene expression has profound implications in understanding human physiology and diseases. Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome including obesity and diabetes which elevate the risk of hepatocellular carcinoma (HCC) especially in male. This review focuses on the molecular connections between metabolic dysfunction and aberrant epigenetic alterations in the development of HCC in NAFLD. The metabolites derived from excessive insulin, glucose and lipid may perturb epigenetic gene regulation through DNA methylation, histone modifications, and RNA interference, leading to activation of pro-inflammatory signaling and deregulation of metabolic pathways. The interplay and crosstalk of chromatin-modifying enzymes, microRNAs, signaling pathways and the downstream transcription factors result in epigenomic reprogramming that drives hepatocellular transformation. The interactions between sex hormone pathways and the epigenetic machineries that influence chromatin states in NAFLD provide potential molecular mechanisms of gender disparity in HCC. A deeper understanding of these connections and comprehensive molecular catalog of hepatocarcinogenesis may shed light in the identification of druggable epigenetic targets for the prevention and treatment of HCC in obese or diabetic patients.
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153
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How are mammalian methionine adenosyltransferases regulated in the liver? A focus on redox stress. FEBS Lett 2013; 587:1711-6. [PMID: 23669363 DOI: 10.1016/j.febslet.2013.04.034] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 04/24/2013] [Accepted: 04/28/2013] [Indexed: 12/20/2022]
Abstract
S-adenosylmethionine synthesis is a key process for cell function, and needs to be regulated at multiple levels. In recent years, advances in the knowledge of methionine adenosyltransferases have been significant. The discovery of nuclear localization of these enzymes suggests their transport to provide the methyl donor, S-adenosylmethionine, for DNA and histone methyltransferases in epigenetic modifications, opening new regulatory possibilities. Previous hypotheses considered only the cytoplasmic regulation of these enzymes, hence the need of an update to integrate recent findings. Here, we focus mainly on the liver and redox mechanisms, and their putative effects on localization and interactions of methionine adenosyltransferases.
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154
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Huidobro C, Fernandez AF, Fraga MF. The role of genetics in the establishment and maintenance of the epigenome. Cell Mol Life Sci 2013; 70:1543-73. [PMID: 23474979 PMCID: PMC11113764 DOI: 10.1007/s00018-013-1296-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 02/05/2013] [Accepted: 02/05/2013] [Indexed: 12/19/2022]
Abstract
Epigenetic mechanisms play an important role in gene regulation during development. DNA methylation, which is probably the most important and best-studied epigenetic mechanism, can be abnormally regulated in common pathologies, but the origin of altered DNA methylation remains unknown. Recent research suggests that these epigenetic alterations could depend, at least in part, on genetic mutations or polymorphisms in DNA methyltransferases and certain genes encoding enzymes of the one-carbon metabolism pathway. Indeed, the de novo methyltransferase 3B (DNMT3B) has been recently found to be mutated in several types of cancer and in the immunodeficiency, centromeric region instability and facial anomalies syndrome (ICF), in which these mutations could be related to the loss of global DNA methylation. In addition, mutations in glycine-N-methyltransferase (GNMT) could be associated with a higher risk of hepatocellular carcinoma and liver disease due to an unbalanced S-adenosylmethionine (SAM)/S-adenosylhomocysteine (SAH) ratio, which leads to aberrant methylation reactions. Also, genetic variants of chromatin remodeling proteins and histone tail modifiers are involved in genetic disorders like α thalassemia X-linked mental retardation syndrome, CHARGE syndrome, Cockayne syndrome, Rett syndrome, systemic lupus erythematous, Rubinstein-Taybi syndrome, Coffin-Lowry syndrome, Sotos syndrome, and facioescapulohumeral syndrome, among others. Here, we review the potential genetic alterations with a possible role on epigenetic factors and discuss their contribution to human disease.
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Affiliation(s)
- Covadonga Huidobro
- Cancer Epigenetics Laboratory, Institute of Oncology of Asturias (IUOPA-HUCA), University of Oviedo, Oviedo, Spain
| | - Agustin F. Fernandez
- Cancer Epigenetics Laboratory, Institute of Oncology of Asturias (IUOPA-HUCA), University of Oviedo, Oviedo, Spain
| | - Mario F. Fraga
- Cancer Epigenetics Laboratory, Institute of Oncology of Asturias (IUOPA-HUCA), University of Oviedo, Oviedo, Spain
- Department of Immunology and Oncology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
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155
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Mehedint MG, Zeisel SH. Choline's role in maintaining liver function: new evidence for epigenetic mechanisms. Curr Opin Clin Nutr Metab Care 2013; 16:339-45. [PMID: 23493015 PMCID: PMC3729018 DOI: 10.1097/mco.0b013e3283600d46] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
PURPOSE OF REVIEW Humans eating diets low in choline develop fatty liver and liver damage. Rodents fed choline-methionine-deficient diets not only develop fatty liver, but also progress to develop fibrosis and hepatocarcinoma. This review focuses on the role of choline in liver function, with special emphasis on the epigenetic mechanisms of action. RECENT FINDINGS Dietary intake of methyl donors like choline influences the methylation of DNA and histones, thereby altering the epigenetic regulation of gene expression. The liver is the major organ within which methylation reactions occur, and many of the hepatic genes involved in pathways for the development of fatty liver, hepatic fibrosis, and hepatocarcinomas are epigenetically regulated. SUMMARY Dietary intake of choline varies over a three-fold range and many humans have genetic polymorphisms that increase their demand for choline. Choline is an important methyl donor needed for the generation of S-adenosylmethionine. Dietary choline intake is an important modifier of epigenetic marks on DNA and histones, and thereby modulates the gene expression in many of the pathways involved in liver function and dysfunction.
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Affiliation(s)
- Mihai G Mehedint
- Nutrition Research Institute at Kannapolis, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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156
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Zhang J, Gong C, Bing Y, Li T, Liu Z, Liu Q. Hypermethylation-repressed methionine adenosyltransferase 1A as a potential biomarker for hepatocellular carcinoma. Hepatol Res 2013; 43:374-83. [PMID: 23072598 DOI: 10.1111/j.1872-034x.2012.01099.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Revised: 08/09/2012] [Accepted: 08/27/2012] [Indexed: 12/25/2022]
Abstract
AIM Methionine adenosyltransferase 1A (MAT1A) is inactivated in HCC and may be stimulated by an epigenetic change involving promoter hypermethylation in hepatocarcinogenesis. However, the possible clinical impact and prognosis of this inactivation have not been investigated. METHODS We studied the methylation status of the CpG sites in the promoter region and the mRNA and protein expression of MAT1A in HCC and corresponding adjacent non-tumor tissues using methylation-specific polymerase chain reaction, reverse transcription polymerase chain reaction and immunohistochemistry techniques. RESULTS MAT1A promoter methylation was significantly higher in HCC than that in adjacent non-tumor tissues (P < 0.0001). Bisulfite sequencing showed that the four CpG sites were hypermethylated in HCC while hypomethylation was found in the corresponding adjacent non-tumor tissues. Furthermore, MAT1A methylation was significantly associated with protein expression (P = 0.022). Low expression of MAT1A was correlated with larger tumor size, higher tumor-node-metastasis stage, positive hepatitis B surface antigen status and high α-fetoprotein (AFP) serum levels (P < 0.05). MAT1A promoter methylation was also correlated with high AFP serum level (P < 0.05). In univariate survival analysis, low expression of MAT1A was significantly associated with shortened patient survival (P < 0.001). Furthermore, in multivariate analysis, MAT1A expression was found as an independent prognostic factor (P = 0.016). CONCLUSION Our observations suggest that hypermethylation of the MAT1A promoter may be one of the events in the development of HCC. Low expression of MAT1A is likely involved in the progression of the tumor and was found to be an independent factor for poor prognosis of patients with HCC.
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Affiliation(s)
- Jin Zhang
- Department of General Surgery, Research Center of Digestive Diseases, Zhongnan Hospital, Wuhan University, Wuhan, China
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157
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Calvisi DF, Frau M, Tomasi ML, Feo F, Pascale RM. Deregulation of signalling pathways in prognostic subtypes of hepatocellular carcinoma: novel insights from interspecies comparison. Biochim Biophys Acta Rev Cancer 2013; 1826:215-37. [PMID: 23393659 DOI: 10.1016/j.bbcan.2012.04.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepatocellular carcinoma is a frequent and fatal disease. Recent researches on rodent models and human hepatocarcinogenesis contributed to unravel the molecular mechanisms of hepatocellular carcinoma dedifferentiation and progression, and allowed the discovery of several alterations underlying the deregulation of cell cycle and signalling pathways. This review provides an interpretive analysis of the results of these studies. Mounting evidence emphasises the role of up-regulation of RAS/ERK, P13K/AKT, IKK/NF-kB, WNT, TGF-ß, NOTCH, Hedgehog, and Hippo signalling pathways as well as of aberrant proteasomal activity in hepatocarcinogenesis. Signalling deregulation often occurs in preneoplastic stages of rodent and human hepatocarcinogenesis and progressively increases in carcinomas, being most pronounced in more aggressive tumours. Numerous changes in signalling cascades are involved in the deregulation of carbohydrate, lipid, and methionine metabolism, which play a role in the maintenance of the transformed phenotype. Recent studies on the role of microRNAs in signalling deregulation, and on the interplay between signalling pathways led to crucial achievements in the knowledge of the network of signalling cascades, essential for the development of adjuvant therapies of liver cancer. Furthermore, the analysis of the mechanisms involved in signalling deregulation allowed the identification of numerous putative prognostic markers and novel therapeutic targets of specific hepatocellular carcinoma subtypes associated with different biologic and clinical features. This is of prime importance for the selection of patient subgroups that are most likely to obtain clinical benefit and, hence, for successful development of targeted therapies for liver cancer.
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Affiliation(s)
- Diego F Calvisi
- Department of Clinical and Experimental Medicine, Division of Experimental Pathology and Oncology, University of Sassari, Sassari, Italy
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158
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159
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Pogribny IP, Kutanzi K, Melnyk S, de Conti A, Tryndyak V, Montgomery B, Pogribna M, Muskhelishvili L, Latendresse JR, James SJ, Beland FA, Rusyn I. Strain-dependent dysregulation of one-carbon metabolism in male mice is associated with choline- and folate-deficient diet-induced liver injury. FASEB J 2013; 27:2233-43. [PMID: 23439872 DOI: 10.1096/fj.12-227116] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Dysregulation of one-carbon metabolism-related metabolic processes is a major contributor to the pathogenesis of nonalcoholic fatty liver disease (NAFLD). It is well established that genetic and gender-specific variations in one-carbon metabolism contribute to the vulnerability to NAFLD in humans. To examine the role of one-carbon metabolism dysregulation in the pathogenesis and individual susceptibility to NAFLD, we used a "population-based" mouse model where male mice from 7 inbred were fed a choline- and folate-deficient (CFD) diet for 12 wk. Strain-dependent down-regulation of several key one-carbon metabolism genes, including methionine adenosyltransferase 1α (Mat1a), cystathionine-β-synthase (Cbs), methylenetetrahydrofolate reductase (Mthfr), adenosyl-homocysteinase (Ahcy), and methylenetetrahydrofolate dehydrogenase 1 (Mthfd1), was observed. These changes were strongly associated with interstrain variability in liver injury (steatosis, necrosis, inflammation, and activation of fibrogenesis) and hyperhomocysteinemia. Mechanistically, the decreased expression of Mat1a, Ahcy, and Mthfd1 was linked to a reduced level and promoter binding of transcription factor CCAAT/enhancer binding protein β (CEBPβ), which directly regulates their transcription. The strain specificity of diet-induced dysregulation of one-carbon metabolism suggests that interstrain variation in the regulation of one-carbon metabolism may contribute to the differential vulnerability to NFLD and that correcting the imbalance may be considered as preventive and treatment strategies for NAFLD.
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Affiliation(s)
- Igor P Pogribny
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA.
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160
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Purohit V, Rapaka R, Kwon OS, Song BJ. Roles of alcohol and tobacco exposure in the development of hepatocellular carcinoma. Life Sci 2013; 92:3-9. [PMID: 23123447 PMCID: PMC3822918 DOI: 10.1016/j.lfs.2012.10.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 10/01/2012] [Accepted: 10/10/2012] [Indexed: 12/11/2022]
Abstract
The purpose of this report is to summarize the roles of alcohol and tobacco exposure in the development of hepatocellular carcinoma (HCC). Chronic heavy alcohol exposure is a major risk factor for HCC, which is the most frequent type of liver cancer. Alcohol ingestion may initiate and or promote the development of HCC by: 1) acetaldehyde-DNA adduct formation; 2) cytochrome P4502E1-associated reactive oxygen species (ROS) generation , lipid peroxidation, p53 mutation, and conversion of pro-carcinogens to carcinogens; 3) iron accumulation that leads to ROS generation, lipid peroxidation, p53 mutation, and initiation of inflammatory cascade via nuclear factor-KappaB (NF-kB) activation; 4) glutathione depletion leading to oxidative stress; 5) s-adenosylmethionine (SAM) depletion and associated DNA hypomethylation of oncogenes ; 6) retinoic acid depletion and resultant hepatocyte proliferation via up-regulation of activator protein-1 (AP-1); 7) initiating an inflammatory cascade through increased transfer of endotoxin from intestine to liver, Kupffer cell activation via CD14/toll-like receptor-4 (TLR-4), oxidative stress, NF-kB or early growth response-1(Egr-1) activation, and generation of inflammatory cytokines and chemokines; 8) induction of liver fibrosis; and 9) decreasing the number and/or function of natural killer cells. Tobacco exposure is also a risk factor for HCC. It may contribute to the initiation and promotion of HCC due the presence of mutagenic and carcinogenic compounds as well as by causing oxidative stress due to generation of ROS and depletion of endogenous antioxidants. Simultaneous exposure to alcohol and tobacco is expected to promote the development of HCC in an additive and/or synergistic manner.
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Affiliation(s)
- Vishnudutt Purohit
- Chemistry and Physiological Systems Research Branch, Division of Basic Neuroscience & Behavioral Research, National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD 20892, USA.
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161
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Tamiya H, Hirota K, Takahashi Y, Daitoku H, Kaneko Y, Sakuta G, Iizuka K, Watanabe S, Ishii N, Fukamizu A. Conserved SAMS function in regulating egg-laying in C. elegans. J Recept Signal Transduct Res 2013; 33:56-62. [PMID: 23316847 DOI: 10.3109/10799893.2012.756896] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
S-adenosyl-L-methionine (SAM) is an intermediate metabolite of methionine and serves as the methyl donor for many biological methylation reactions. The synthesis of SAM is catalyzed by SAM synthetase (SAMS), which transfers the adenosyl moiety of adenosine-5'-triphosphate to methionine. In the nematode Caenorhabditis elegans, four sams family genes, sams-1, -3, -4 and -5, are predicted to encode SAMS proteins. However, their physiological roles remain unclear. Here we show that the four predicted SAMS proteins in fact have the ability to catalyze the formation of SAM in vitro, and revealed that only sams-1 mutant animals among the family genes exhibited a significant reduction in egg-laying. Using transgenic animals carrying a transcriptional reporter for each sams gene promoter, we observed that each sams promoter confers a distinct expression pattern with respect to tissue, time of expression and expression level (i.e. promoter specificity). Promoter-swap experiments revealed that the ectopic expression of SAMS-3, -4 or -5 driven by the sams-1 promoter completely rescued egg-laying in sams-1 mutants. These data indicate that SAMS protein function is conserved throughout the entire family.
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Affiliation(s)
- Hiroko Tamiya
- Life Science Center, Tsukuba Advanced Research Alliance, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki, Japan
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162
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Guzmán C, Benet M, Pisonero-Vaquero S, Moya M, García-Mediavilla MV, Martínez-Chantar ML, González-Gallego J, Castell JV, Sánchez-Campos S, Jover R. The human liver fatty acid binding protein (FABP1) gene is activated by FOXA1 and PPARα; and repressed by C/EBPα: Implications in FABP1 down-regulation in nonalcoholic fatty liver disease. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:803-18. [PMID: 23318274 DOI: 10.1016/j.bbalip.2012.12.014] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 11/22/2012] [Accepted: 12/27/2012] [Indexed: 01/24/2023]
Abstract
Liver fatty acid binding protein (FABP1) prevents lipotoxicity of free fatty acids and regulates fatty acid trafficking and partition. Our objective is to investigate the transcription factors controlling the human FABP1 gene and their regulation in nonalcoholic fatty liver disease (NAFLD). Adenovirus-mediated expression of multiple transcription factors in HepG2 cells and cultured human hepatocytes demonstrated that FOXA1 and PPARα are among the most effective activators of human FABP1, whereas C/EBPα is a major dominant repressor. Moreover, FOXA1 and PPARα induced re-distribution of FABP1 protein and increased cytoplasmic expression. Reporter assays demonstrated that the major basal activity of the human FABP1 promoter locates between -96 and -229bp, where C/EBPα binds to a composite DR1-C/EBP element. Mutation of this element at -123bp diminished basal reporter activity, abolished repression by C/EBPα and reduced transactivation by HNF4α. Moreover, HNF4α gene silencing by shRNA in HepG2 cells caused a significant down-regulation of FABP1 mRNA expression. FOXA1 activated the FABP1 promoter through binding to a cluster of elements between -229 and -592bp, whereas PPARα operated through a conserved proximal element at -59bp. Finally, FABP1, FOXA1 and PPARα were concomitantly repressed in animal models of NAFLD and in human nonalcoholic fatty livers, whereas C/EBPα was induced or did not change. We conclude that human FABP1 has a complex mechanism of regulation where C/EBPα displaces HNF4α and hampers activation by FOXA1 and PPARα. Alteration of expression of these transcription factors in NAFLD leads to FABP1 gen repression and could exacerbate lipotoxicity and disease progression.
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Affiliation(s)
- Carla Guzmán
- Experimental Hepatology Unit, IIS Hospital La Fe, Valencia, Spain
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163
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Changes in the hepatic mitochondrial and membrane proteome in mice fed a non-alcoholic steatohepatitis inducing diet. J Proteomics 2013; 80:107-22. [PMID: 23313215 DOI: 10.1016/j.jprot.2012.12.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 11/30/2012] [Accepted: 12/17/2012] [Indexed: 12/20/2022]
Abstract
Non-alcoholic steatohepatitis (NASH) accounts for a large proportion of cryptic cirrhosis in the Western societies. Nevertheless, we lack a deeper understanding of the underlying pathomolecular processes, particularly those preceding hepatic inflammation and fibrosis. In order to gain novel insights into early NASH-development from the first appearance of proteomic alterations to the onset of hepatic inflammation and fibrosis, we conducted a time-course analysis of proteomic changes in liver mitochondria and membrane-enriched fractions of female C57Bl/6N mice fed either a mere steatosis or NASH inducing diet. This data was complemented by quantitative measurements of hepatic glycerol-containing lipids, cholesterol and intermediates of the methionine cycle. Aside from energy metabolism and stress response proteins, enzymes of the urea cycle and methionine metabolism were found regulated. Alterations in the methionine cycle occur early in disease progression preceding molecular signs of inflammation. Proteins that hold particular promise in the early distinction between benign steatosis and NASH are methyl-transferase Mettl7b, the glycoprotein basigin and the microsomal glutathione-transferase.
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164
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Yang H, Cho ME, Li TWH, Peng H, Ko KS, Mato JM, Lu SC. MicroRNAs regulate methionine adenosyltransferase 1A expression in hepatocellular carcinoma. J Clin Invest 2012; 123:285-98. [PMID: 23241961 DOI: 10.1172/jci63861] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 10/18/2012] [Indexed: 12/11/2022] Open
Abstract
MicroRNAs (miRNAs) and methionine adenosyltransferase 1A (MAT1A) are dysregulated in hepatocellular carcinoma (HCC), and reduced MAT1A expression correlates with worse HCC prognosis. Expression of miR-664, miR-485-3p, and miR-495, potential regulatory miRNAs of MAT1A, is increased in HCC. Knockdown of these miRNAs individually in Hep3B and HepG2 cells induced MAT1A expression, reduced growth, and increased apoptosis, while combined knockdown exerted additional effects on all parameters. Subcutaneous and intraparenchymal injection of Hep3B cells stably overexpressing each of this trio of miRNAs promoted tumorigenesis and metastasis in mice. Treatment with miRNA-664 (miR-664), miR-485-3p, and miR-495 siRNAs reduced tumor growth, invasion, and metastasis in an orthotopic liver cancer model. Blocking MAT1A induction significantly reduced the antitumorigenic effect of miR-495 siRNA, whereas maintaining MAT1A expression prevented miRNA-mediated enhancement of growth and metastasis. Knockdown of these miRNAs increased total and nuclear level of MAT1A protein, global CpG methylation, lin-28 homolog B (Caenorhabditis elegans) (LIN28B) promoter methylation, and reduced LIN28B expression. The opposite occurred with forced expression of these miRNAs. In conclusion, upregulation of miR-664, miR-485-3p, and miR-495 contributes to lower MAT1A expression in HCC, and enhanced tumorigenesis may provide potential targets for HCC therapy.
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Affiliation(s)
- Heping Yang
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine of University of Southern California, Los Angeles, California 90033, USA
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165
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Ye P, Cheah IK, Halliwell B. High fat diets and pathology in the guinea pig. Atherosclerosis or liver damage? Biochim Biophys Acta Mol Basis Dis 2012. [PMID: 23195951 DOI: 10.1016/j.bbadis.2012.11.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Animal models have been widely used to investigate the relationship between diet and atherosclerosis and also to study disease etiology and possible interventions. Guinea pigs have been suggested to be a more "realistic" model for atherosclerosis due to their many similarities to humans. However, few published studies actually reported observations of characteristic atherosclerotic lesions and even fewer of advanced lesions. Studies, by our group, of guinea pigs fed on a high-fat diet revealed similar observations, with indications primarily of fatty streaks but little evidence of atherosclerotic plaques. This review discusses the feasibility of the guinea pig as a model for dietary-induced atherosclerosis. As it stands, current evidence raises doubt as to whether guinea pigs could serve as a realistic model for atherosclerosis. However, our own data and the literature suggest that they could be useful models for studying lipoprotein metabolism, non-alcoholic fatty liver disease, and dietary interventions which may help regulate these conditions.
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Affiliation(s)
- Peng Ye
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore
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166
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González B, Garrido F, Ortega R, Martínez-Júlvez M, Revilla-Guarinos A, Pérez-Pertejo Y, Velázquez-Campoy A, Sanz-Aparicio J, Pajares MA. NADP+ binding to the regulatory subunit of methionine adenosyltransferase II increases intersubunit binding affinity in the hetero-trimer. PLoS One 2012. [PMID: 23189196 PMCID: PMC3506619 DOI: 10.1371/journal.pone.0050329] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Mammalian methionine adenosyltransferase II (MAT II) is the only hetero-oligomer in this family of enzymes that synthesize S-adenosylmethionine using methionine and ATP as substrates. Binding of regulatory β subunits and catalytic α2 dimers is known to increase the affinity for methionine, although scarce additional information about this interaction is available. This work reports the use of recombinant α2 and β subunits to produce oligomers showing kinetic parameters comparable to MAT II purified from several tissues. According to isothermal titration calorimetry data and densitometric scanning of the stained hetero-oligomer bands on denatured gels, the composition of these oligomers is that of a hetero-trimer with α2 dimers associated to single β subunits. Additionally, the regulatory subunit is able to bind NADP(+) with a 1:1 stoichiometry, the cofactor enhancing β to α2-dimer binding affinity. Mutants lacking residues involved in NADP(+) binding and N-terminal truncations of the β subunit were able to oligomerize with α2-dimers, although the kinetic properties appeared altered. These data together suggest a role for both parts of the sequence in the regulatory role exerted by the β subunit on catalysis. Moreover, preparation of a structural model for the hetero-oligomer, using the available crystal data, allowed prediction of the regions involved in β to α2-dimer interaction. Finally, the implications that the presence of different N-terminals in the β subunit could have on MAT II behavior are discussed in light of the recent identification of several splicing forms of this subunit in hepatoma cells.
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Affiliation(s)
- Beatriz González
- Departamento de Cristalografía y Biología Estructural, Instituto de Química-Física “Rocasolano” (CSIC), Madrid, Spain
| | - Francisco Garrido
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC-UAM), Madrid, Spain
| | - Rebeca Ortega
- Departamento de Cristalografía y Biología Estructural, Instituto de Química-Física “Rocasolano” (CSIC), Madrid, Spain
| | - Marta Martínez-Júlvez
- Departmento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
- Instituto de Biocomputación y Física de Complejos, Unidad Asociada IQFR-BIFI, Mariano Esquillor s/n, Edificio I+D, Campus Rio Ebro, Zaragoza, Spain
| | | | - Yolanda Pérez-Pertejo
- Departamento de Farmacología y Toxicología (INTOXCAL), Universidad de León, Campus de Vegazana s/n, León, Spain
| | - Adrián Velázquez-Campoy
- Departmento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Zaragoza, Spain
- Instituto de Biocomputación y Física de Complejos, Unidad Asociada IQFR-BIFI, Mariano Esquillor s/n, Edificio I+D, Campus Rio Ebro, Zaragoza, Spain
- Fundacion ARAID, Diputación General de Aragón, Zaragoza, Spain
| | - Julia Sanz-Aparicio
- Departamento de Cristalografía y Biología Estructural, Instituto de Química-Física “Rocasolano” (CSIC), Madrid, Spain
| | - María A. Pajares
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC-UAM), Madrid, Spain
- Molecular Hepatology Group, IdiPAZ, Madrid, Spain
- * E-mail:
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167
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Anstee QM, Day CP. S-adenosylmethionine (SAMe) therapy in liver disease: a review of current evidence and clinical utility. J Hepatol 2012; 57:1097-109. [PMID: 22659519 DOI: 10.1016/j.jhep.2012.04.041] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 04/12/2012] [Accepted: 04/15/2012] [Indexed: 12/13/2022]
Abstract
S-adenosyl-L-methionine (SAMe; AdoMet) is an important, metabolically pleiotropic molecule that participates in multiple cellular reactions as the precursor for the synthesis of glutathione and principle methyl donor required for methylation of nucleic acids, phospholipids, histones, biogenic amines, and proteins. SAMe synthesis is depressed in chronic liver disease and so there has been considerable interest in the utility of SAMe to ameliorate disease severity. Despite encouraging pre-clinical data confirming that SAMe depletion can exacerbate liver injury and supporting a hepatoprotective role for SAMe therapy, to date no large, high-quality randomised clinical trials have been performed that establish clinical utility in specific disease states. Here, we offer an in-depth review of the published scientific literature relating to the physiological and pathophysiological roles of SAMe and its therapeutic use in liver disease, critically assessing implications for clinical practice and offering recommendations for further research.
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Affiliation(s)
- Quentin M Anstee
- Liver Research Group, Institute of Cellular Medicine, The Medical School, Newcastle University, Framlington Place, Newcastle-Upon-Tyne NE2 4HH, UK.
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168
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Abstract
The purpose of this report is to summarize the roles of alcohol and tobacco exposure in the development of hepatocellular carcinoma (HCC). Chronic heavy alcohol exposure is a major risk factor for HCC, which is the most frequent type of liver cancer. Alcohol ingestion may initiate and or promote the development of HCC by: 1) acetaldehyde-DNA adduct formation; 2) cytochrome P4502E1-associated reactive oxygen species (ROS) generation , lipid peroxidation, p53 mutation, and conversion of pro-carcinogens to carcinogens; 3) iron accumulation that leads to ROS generation, lipid peroxidation, p53 mutation, and initiation of inflammatory cascade via nuclear factor-KappaB (NF-kB) activation; 4) glutathione depletion leading to oxidative stress; 5) s-adenosylmethionine (SAM) depletion and associated DNA hypomethylation of oncogenes ; 6) retinoic acid depletion and resultant hepatocyte proliferation via up-regulation of activator protein-1 (AP-1); 7) initiating an inflammatory cascade through increased transfer of endotoxin from intestine to liver, Kupffer cell activation via CD14/toll-like receptor-4 (TLR-4), oxidative stress, NF-kB or early growth response-1(Egr-1) activation, and generation of inflammatory cytokines and chemokines; 8) induction of liver fibrosis; and 9) decreasing the number and/or function of natural killer cells. Tobacco exposure is also a risk factor for HCC. It may contribute to the initiation and promotion of HCC due the presence of mutagenic and carcinogenic compounds as well as by causing oxidative stress due to generation of ROS and depletion of endogenous antioxidants. Simultaneous exposure to alcohol and tobacco is expected to promote the development of HCC in an additive and/or synergistic manner.
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169
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Mitochondrial GSH determines the toxic or therapeutic potential of superoxide scavenging in steatohepatitis. J Hepatol 2012; 57:852-9. [PMID: 22687340 PMCID: PMC3445734 DOI: 10.1016/j.jhep.2012.05.024] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 04/16/2012] [Accepted: 05/25/2012] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Steatohepatitis (SH) is associated with mitochondrial dysfunction and excessive production of superoxide, which can then be converted into H(2)O(2) by SOD2. Since mitochondrial GSH (mGSH) plays a critical role in H(2)O(2) reduction, we explored the interplay between superoxide, H(2)O(2), and mGSH in nutritional and genetic models of SH, which exhibit mGSH depletion. METHODS We used isolated mitochondria and primary hepatocytes, as well as in vivo SH models showing mGSH depletion to test the consequences of superoxide scavenging. RESULTS In isolated mitochondria and primary hepatocytes, superoxide scavenging by SOD mimetics or purified SOD decreased superoxide and peroxynitrite generation but increased H(2)O(2) following mGSH depletion, despite mitochondrial peroxiredoxin/thioredoxin defense. Selective mGSH depletion sensitized hepatocytes to cell death induced by SOD mimetics, and this was prevented by RIP1 kinase inhibition with necrostatin-1 or GSH repletion with GSH ethyl ester (GSHee). Mice fed the methionine-choline deficient (MCD) diet or MAT1A(-/-) mice exhibited reduced SOD2 activity; in vivo treatment with SOD mimetics increased liver damage, inflammation, and fibrosis, despite a decreased superoxide and 3-nitrotyrosine immunoreactivity, effects that were ameliorated by mGSH replenishment with GSHee, but not NAC. As a proof-of-principle of the detrimental role of superoxide scavenging when mGSH was depleted transgenic mice overexpressing SOD2 exhibited enhanced susceptibility to MCD-mediated SH. CONCLUSIONS These findings underscore a critical role for mGSH in the therapeutic potential of superoxide scavenging in SH, and suggest that the combined approach of superoxide scavenging with mGSH replenishment may be important in SH.
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170
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Abstract
S-adenosylmethionine (AdoMet, also known as SAM and SAMe) is the principal biological methyl donor synthesized in all mammalian cells but most abundantly in the liver. Biosynthesis of AdoMet requires the enzyme methionine adenosyltransferase (MAT). In mammals, two genes, MAT1A that is largely expressed by normal liver and MAT2A that is expressed by all extrahepatic tissues, encode MAT. Patients with chronic liver disease have reduced MAT activity and AdoMet levels. Mice lacking Mat1a have reduced hepatic AdoMet levels and develop oxidative stress, steatohepatitis, and hepatocellular carcinoma (HCC). In these mice, several signaling pathways are abnormal that can contribute to HCC formation. However, injury and HCC also occur if hepatic AdoMet level is excessive chronically. This can result from inactive mutation of the enzyme glycine N-methyltransferase (GNMT). Children with GNMT mutation have elevated liver transaminases, and Gnmt knockout mice develop liver injury, fibrosis, and HCC. Thus a normal hepatic AdoMet level is necessary to maintain liver health and prevent injury and HCC. AdoMet is effective in cholestasis of pregnancy, and its role in other human liver diseases remains to be better defined. In experimental models, it is effective as a chemopreventive agent in HCC and perhaps other forms of cancer as well.
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Affiliation(s)
- Shelly C Lu
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine, Los Angeles, California 90033, USA.
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171
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Thomas A, Stevens AP, Klein MS, Hellerbrand C, Dettmer K, Gronwald W, Oefner PJ, Reinders J. Early changes in the liver-soluble proteome from mice fed a nonalcoholic steatohepatitis inducing diet. Proteomics 2012; 12:1437-51. [PMID: 22589191 DOI: 10.1002/pmic.201100628] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Despite the increasing incidence of nonalcoholic steatohepatitis (NASH) with the rise in lifestyle-related diseases such as the metabolic syndrome, little is known about the changes in the liver proteome that precede the onset of inflammation and fibrosis. Here, we investigated early changes in the liver-soluble proteome of female C57BL/6N mice fed an NASH-inducing diet by 2D-DIGE and nano-HPLC-MS/MS. In parallel, histology and measurements of hepatic content of triglycerides, cholesterol and intermediates of the methionine cycle were performed. Hepatic steatosis manifested itself after 2 days of feeding, albeit significant changes in the liver-soluble proteome were not evident before day 10 in the absence of inflammatory or fibrotic signs. Proteomic alterations affected mainly energy and amino acid metabolism, detoxification processes, urea cycle, and the one-carbon/S-adenosylmethionine pathways. Additionally, intermediates of relevant affected pathways were quantified from liver tissue, confirming the findings from the proteomic analysis.
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Affiliation(s)
- Anja Thomas
- Institute of Functional Genomics, University of Regensburg, Josef-Engert-Strasse 9, Regensburg, Germany
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172
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Tomasi ML, Tomasi I, Ramani K, Pascale RM, Xu J, Giordano P, Mato JM, Lu SC. S-adenosyl methionine regulates ubiquitin-conjugating enzyme 9 protein expression and sumoylation in murine liver and human cancers. Hepatology 2012; 56:982-93. [PMID: 22407595 PMCID: PMC3378793 DOI: 10.1002/hep.25701] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 02/28/2012] [Indexed: 12/15/2022]
Abstract
UNLABELLED Ubiquitin-conjugating enzyme 9 (Ubc9) is required for sumoylation and is overexpressed in several malignancies, but its expression in hepatocellular carcinoma (HCC) is unknown. Hepatic S-adenosyl methionine (SAMe) levels decrease in methionine adenosyltransferase 1A (Mat1a) knockout (KO) mice, which develop HCC, and in ethanol-fed mice. We examined the regulation of Ubc9 by SAMe in murine liver and human HCC, breast, and colon carcinoma cell lines and specimens. Real-time polymerase chain reaction and western blotting measured gene and protein expression, respectively. Immunoprecipitation followed by western blotting examined protein-protein interactions. Ubc9 expression increased in HCC and when hepatic SAMe levels decreased. SAMe treatment in Mat1a KO mice reduced Ubc9 protein, but not messenger RNA (mRNA) levels, and lowered sumoylation. Similarly, treatment of liver cancer cell lines HepG2 and Huh7, colon cancer cell line RKO, and breast cancer cell line MCF-7 with SAMe or its metabolite 5'-methylthioadenosine (MTA) reduced only Ubc9 protein level. Ubc9 posttranslational regulation is unknown. Ubc9 sequence predicted a possible phosphorylation site by cell division cycle 2 (Cdc2), which directly phosphorylated recombinant Ubc9. Mat1a KO mice had higher phosphorylated (phospho)-Ubc9 levels, which normalized after SAMe treatment. SAMe and MTA treatment lowered Cdc2 mRNA and protein levels, as well as phospho-Ubc9 and protein sumoylation in liver, colon, and breast cancer cells. Serine 71 of Ubc9 was required for phosphorylation, interaction with Cdc2, and protein stability. Cdc2, Ubc9, and phospho-Ubc9 levels increased in human liver, breast, and colon cancers. CONCLUSION Cdc2 expression is increased and Ubc9 is hyperphosphorylated in several cancers, and this represents a novel mechanism to maintain high Ubc9 protein expression that can be inhibited by SAMe and MTA.
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Affiliation(s)
- Maria Lauda Tomasi
- Division of Gastroenterology and Liver Diseases, Keck School of Medicine of University of Southern California, 90033 Los Angeles, California, USA,USC Research Center for Liver Diseases, Keck School of Medicine of University of Southern California, 90033 Los Angeles, California, USA,The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine of University of Southern California, 90033 Los Angeles, California, USA
| | - Ivan Tomasi
- Department of Colorectal Surgery, Whipps Cross University Hospital, London E11 1NR, UK
| | - Komal Ramani
- Division of Gastroenterology and Liver Diseases, Keck School of Medicine of University of Southern California, 90033 Los Angeles, California, USA,USC Research Center for Liver Diseases, Keck School of Medicine of University of Southern California, 90033 Los Angeles, California, USA,The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine of University of Southern California, 90033 Los Angeles, California, USA
| | - Rosa Maria Pascale
- Division of Experimental Pathology and Oncology, University of Sassari, 07100 Sassari, Italy
| | - Jun Xu
- The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine of University of Southern California, 90033 Los Angeles, California, USA
| | - Pasquale Giordano
- Department of Colorectal Surgery, Whipps Cross University Hospital, London E11 1NR, UK
| | - 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, Keck School of Medicine of University of Southern California, 90033 Los Angeles, California, USA,USC Research Center for Liver Diseases, Keck School of Medicine of University of Southern California, 90033 Los Angeles, California, USA,The Southern California Research Center for Alcoholic and Pancreatic Diseases & Cirrhosis, Keck School of Medicine of University of Southern California, 90033 Los Angeles, California, USA
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173
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Martínez-López N, García-Rodríguez JL, Varela-Rey M, Gutiérrez V, Fernández-Ramos D, Beraza N, Aransay AM, Schlangen K, Lozano JJ, Aspichueta P, Luka Z, Wagner C, Evert M, Calvisi DF, Lu SC, Mato JM, Martínez-Chantar ML. Hepatoma cells from mice deficient in glycine N-methyltransferase have increased RAS signaling and activation of liver kinase B1. Gastroenterology 2012; 143:787-798.e13. [PMID: 22687285 PMCID: PMC3429651 DOI: 10.1053/j.gastro.2012.05.050] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 05/22/2012] [Accepted: 05/26/2012] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS Patients with cirrhosis are at high risk for developing hepatocellular carcinoma (HCC), and their liver tissues have abnormal levels of S-adenosylmethionine (SAMe). Glycine N-methyltransferase (GNMT) catabolizes SAMe, but its expression is down-regulated in HCC cells. Mice that lack GNMT develop fibrosis and hepatomas and have alterations in signaling pathways involved in carcinogenesis. We investigated the role of GNMT in human HCC cell lines and in liver carcinogenesis in mice. METHODS We studied hepatoma cells from GNMT knockout mice and analyzed the roles of liver kinase B1 (LKB1, STK11) signaling via 5'-adenosine monophosphate-activated protein kinase (AMPK) and Ras in regulating proliferation and transformation. RESULTS Hepatoma cells from GNMT mice had defects in LKB1 signaling to AMPK, making them resistant to induction of apoptosis by adenosine 3',5'-cyclic monophosphate activation of protein kinase A and calcium/calmodulin-dependent protein kinase kinase 2. Ras-mediated hyperactivation of LKB1 promoted proliferation of GNMT-deficient hepatoma cells and required mitogen-activated protein kinase 2 (ERK) and ribosomal protein S6 kinase polypeptide 2 (p90RSK). Ras activation of LKB1 required expression of RAS guanyl releasing protein 3 (RASGRP3). Reduced levels of GNMT and phosphorylation of AMPKα at Thr172 and increased levels of Ras, LKB1, and RASGRP3 in HCC samples from patients were associated with shorter survival times. CONCLUSIONS Reduced expression of GNMT in mouse hepatoma cells and human HCC cells appears to increase activity of LKB1 and RAS; activation of RAS signaling to LKB1 and RASGRP3, via ERK and p90RSK, might be involved in liver carcinogenesis and be used as a prognostic marker. Reagents that disrupt this pathway might be developed to treat patients with HCC.
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MESH Headings
- AMP-Activated Protein Kinases/metabolism
- Animals
- Apoptosis
- Azacitidine/pharmacology
- Calcium-Calmodulin-Dependent Protein Kinase Kinase/metabolism
- Carcinoma, Hepatocellular/drug therapy
- Carcinoma, Hepatocellular/enzymology
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/pathology
- Cell Line, Tumor
- Cell Proliferation
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/metabolism
- Cell Transformation, Neoplastic/pathology
- Cyclic AMP-Dependent Protein Kinases/metabolism
- DNA Methylation
- Enzyme Activation
- Enzyme Inhibitors/pharmacology
- Glycine N-Methyltransferase/deficiency
- Glycine N-Methyltransferase/genetics
- Guanine Nucleotide Exchange Factors/metabolism
- Humans
- Liver Neoplasms/drug therapy
- Liver Neoplasms/enzymology
- Liver Neoplasms/genetics
- Liver Neoplasms/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Nude
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase Kinases/metabolism
- Phosphorylation
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- RNA Interference
- Ribosomal Protein S6 Kinases, 90-kDa/metabolism
- Signal Transduction/drug effects
- Time Factors
- Transfection
- Tumor Burden
- ras Guanine Nucleotide Exchange Factors
- ras Proteins/metabolism
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Affiliation(s)
- Nuria Martínez-López
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain.
| | - Juan L García-Rodríguez
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain
| | - Marta Varela-Rey
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain
| | - Virginia Gutiérrez
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain
| | - David Fernández-Ramos
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain
| | - Naiara Beraza
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain
| | - Ana M Aransay
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain
| | - Karin Schlangen
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain
| | - Juan Jose Lozano
- Centro de Investigación Biomédica en red de Enfermedades Hepáticas y Digestivas, Hospital Clinic, Centre Esther Koplovitz, Barcelona, Spain
| | - Patricia Aspichueta
- Department of Physiology, University of the Basque Country Medical School, Bilbao, Spain
| | - Zigmund Luka
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Conrad Wagner
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Matthias Evert
- Institute of Pathology, Ernst-Moritz-Arndt-Universität, Greifswald, Germany
| | - Diego F Calvisi
- Institute of Pathology, Ernst-Moritz-Arndt-Universität, Greifswald, Germany
| | - 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, California
| | - José M Mato
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain
| | - María L Martínez-Chantar
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Technology Park of Bizkaia, Bizkaia, Spain
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174
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Gomez-Santos L, Luka Z, Wagner C, Fernandez-Alvarez S, Lu SC, Mato JM, Martinez-Chantar ML, Beraza N. Inhibition of natural killer cells protects the liver against acute injury in the absence of glycine N-methyltransferase. Hepatology 2012; 56:747-59. [PMID: 22392635 PMCID: PMC3378767 DOI: 10.1002/hep.25694] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 02/28/2012] [Indexed: 12/14/2022]
Abstract
UNLABELLED Glycine N-methyltransferase (GNMT) catabolizes S-adenosylmethionine (SAMe), the main methyl donor of the body. Patients with cirrhosis show attenuated GNMT expression, which is absent in hepatocellular carcinoma (HCC) samples. GNMT(-/-) mice develop spontaneous steatosis that progresses to steatohepatitis, cirrhosis, and HCC. The liver is highly enriched with innate immune cells and plays a key role in the body's host defense and in the regulation of inflammation. Chronic inflammation is the major hallmark of nonalcoholic steatohepatitis (NASH) progression. The aim of our study was to uncover the molecular mechanisms leading to liver chronic inflammation in the absence of GNMT, focusing on the implication of natural killer (NK) / natural killer T (NKT) cells. We found increased expression of T helper (Th)1- over Th2-related cytokines, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-R2/DR5, and several ligands of NK cells in GNMT(-/-) livers. Interestingly, NK cells from GNMT(-/-) mice were spontaneously activated, expressed more TRAIL, and had strong cytotoxic activity, suggesting their contribution to the proinflammatory environment in the liver. Accordingly, NK cells mediated hypersensitivity to concanavalin A (ConA)-mediated hepatitis in GNMT(-/-) mice. Moreover, GNMT(-/-) mice were hypersensitive to endotoxin-mediated liver injury. NK cell depletion and adoptive transfer of TRAIL(-/-) liver-NK cells protected the liver against lipopolysaccharide (LPS) liver damage. CONCLUSION Our data allow us to conclude that TRAIL-producing NK cells actively contribute to promote a proinflammatory environment at early stages of fatty liver disease, suggesting that this cell compartment may contribute to the progression of NASH.
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Affiliation(s)
- Laura Gomez-Santos
- Department of Metabolomics, 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
| | - Conrad Wagner
- Department of Biochemistry, Vanderbilt University, Nashville, TN
- Tennessee Valley Department of Medical Affairs Medical Center, Nashville, TN
| | - Sara Fernandez-Alvarez
- Department of Metabolomics, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), 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
| | - Jose M Mato
- Department of Metabolomics, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Maria L Martinez-Chantar
- Department of Metabolomics, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Naiara Beraza
- Department of Metabolomics, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
- Corresponding Author: Naiara Beraza, PhD, Department of Metabolomics, CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberedh), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain. Tel. 0034/944044592, Fax. 0034944061301,
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175
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Takahashi Y, Soejima Y, Fukusato T. Animal models of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis. World J Gastroenterol 2012; 18:2300-8. [PMID: 22654421 PMCID: PMC3353364 DOI: 10.3748/wjg.v18.i19.2300] [Citation(s) in RCA: 393] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 02/20/2012] [Accepted: 02/26/2012] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a condition in which excess fat accumulates in the liver of a patient without a history of alcohol abuse. Nonalcoholic steatohepatitis (NASH), a severe form of NAFLD, can progress to liver cirrhosis and hepatocellular carcinoma. NAFLD is regarded as a hepatic manifestation of metabolic syndrome and incidence has been increasing worldwide in line with the increased prevalence of obesity, type 2 diabetes, and hyperlipemia. Animal models of NAFLD/NASH give crucial information, not only in elucidating pathogenesis of NAFLD/NASH but also in examining therapeutic effects of various agents. An ideal model of NAFLD/NASH should correctly reflect both hepatic histopathology and pathophysiology of human NAFLD/NASH. Animal models of NAFLD/NASH are divided into genetic, dietary, and combination models. In this paper, we review commonly used animal models of NAFLD/NASH referring to their advantages and disadvantages.
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176
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NF-E2-related factor 1 (Nrf1) serves as a novel regulator of hepatic lipid metabolism through regulation of the Lipin1 and PGC-1β genes. Mol Cell Biol 2012; 32:2760-70. [PMID: 22586274 DOI: 10.1128/mcb.06706-11] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Hepatic lipid metabolism is under elaborate regulation, and perturbations in this regulatory process at the transcriptional level lead to pathological conditions. NF-E2-related factor 1 (Nrf1) is a member of the cap'n'collar (CNC) transcription factor family. Hepatocyte-specific Nrf1 gene conditional-knockout mice are known to develop hepatic steatosis, but it remains unclear how Nrf1 contributes to the lipid homeostasis. Therefore, in this study we examined the gene expression profiles of Nrf1-deficient mouse livers. A pathway analysis based on the profiling results revealed that the levels of expression of the genes related to lipid metabolism, amino acid metabolism, and mitochondrial respiratory function were decreased in Nrf1-deficient mouse livers, indicating the profound effects that the Nrf1 deficiency conferred to various metabolic pathways. We discovered that the Nrf1 deficiency leads to the reduced expression of the transcriptional coactivator genes Lipin1 and PGC-1β (for peroxisome proliferator-activated receptor γ coactivator 1β). Chromatin immunoprecipitation analyses showed that Nrf1 binds to the antioxidant response elements (AREs) in regulatory regions of the Lipin1 and PGC-1β genes and the binding of Nrf1 to the AREs activates reporter gene transcription. These results thus identified Nrf1 to be a novel regulator of the Lipin1 and PGC-1β genes, providing new insights into the Nrf1 function in hepatic lipid metabolism.
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177
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Wang YC, Chiang EPI. Low-dose methotrexate inhibits methionine S-adenosyltransferase in vitro and in vivo. Mol Med 2012; 18:423-32. [PMID: 22193356 DOI: 10.2119/molmed.2011.00048] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 12/19/2011] [Indexed: 12/29/2022] Open
Abstract
Methionine S-adenosyltransferase (MAT) catalyzes the only reaction that produces the major methyl donor in mammals. Low-dose methotrexate is the most commonly used disease-modifying antirheumatic drug in human rheumatic conditions. The present study was conducted to test the hypothesis that methotrexate inhibits MAT expression and activity in vitro and in vivo. HepG2 cells were cultured under folate restriction or in low-dose methotrexate with and without folate or methionine supplementation. Male C57BL/6J mice received methotrexate regimens that reflected low-dose clinical use in humans. S-adenosylmethionine and MAT genes, proteins and enzyme activity levels were determined. We found that methionine or folate supplementation greatly improved S-adenosylmethionine in folate-depleted cells but not in cells preexposed to methotrexate. Methotrexate but not folate depletion suppressed MAT genes, proteins and activity in vitro. Low-dose methotrexate inhibited MAT1A and MAT2A genes, MATI/II/III proteins and MAT enzyme activities in mouse tissues. Concurrent folinate supplementation with methotrexate ameliorated MAT2A reduction and restored S-adenosylmethionine in HepG2 cells. However, posttreatment folinate rescue failed to restore MAT2A reduction or S-adenosylmethionine level in cells preexposed to methotrexate. Our results provide both in vitro and in vivo evidence that low-dose methotrexate inhibits MAT genes, proteins, and enzyme activity independent of folate depletion. Because polyglutamated methotrexate stays in the hepatocytes, if methotrexate inhibits MAT in the liver, then the efficacy of clinical folinate rescue with respect to maintaining hepatic S-adenosylmethionine synthesis and normalizing the methylation reactions would be limited. These findings raise concerns on perturbed methylation reactions in humans on low-dose methotrexate. Future studies on the clinical physiological consequences of MAT inhibition by methotrexate and the potential benefits of S-adenosylmethionine supplementation on methyl group homeostasis in clinical methotrexate therapies are warranted.
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Affiliation(s)
- Yi-Cheng Wang
- Department of Food Science and Biotechnology, National Chung Hsing University, Taichung, Taiwan, Republic of China
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178
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Yamada H, Akahoshi N, Kamata S, Hagiya Y, Hishiki T, Nagahata Y, Matsuura T, Takano N, Mori M, Ishizaki Y, Izumi T, Kumagai Y, Kasahara T, Suematsu M, Ishii I. Methionine excess in diet induces acute lethal hepatitis in mice lacking cystathionine γ-lyase, an animal model of cystathioninuria. Free Radic Biol Med 2012; 52:1716-26. [PMID: 22387178 DOI: 10.1016/j.freeradbiomed.2012.02.033] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 02/15/2012] [Accepted: 02/22/2012] [Indexed: 01/08/2023]
Abstract
Physiological roles of the transsulfuration pathway have been recognized by its contribution to the synthesis of cytoprotective cysteine metabolites, such as glutathione, taurine/hypotaurine, and hydrogen sulfide (H(2)S), whereas its roles in protecting against methionine toxicity remained to be clarified. This study aimed at revealing these roles by analyzing high-methionine diet-fed transsulfuration-defective cystathionine γ-lyase-deficient (Cth(-/-)) mice. Wild-type and Cth(-/-) mice were fed a standard diet (1 × Met: 0.44%) or a high-methionine diet (3 × Met or 6 × Met), and hepatic conditions were monitored by serum biochemistry and histology. Metabolome analysis was performed for methionine derivatives using capillary electrophoresis- or liquid chromatography-mass spectrometry and sulfur-detecting gas chromatography. The 6 × Met-fed Cth(-/-) (not 1 × Met-fed Cth(-/-) or 6 × Met-fed wild type) mice displayed acute hepatitis, which was characterized by markedly elevated levels of serum alanine/aspartate aminotransferases and serum/hepatic lipid peroxidation, inflammatory cell infiltration, and hepatocyte ballooning; thereafter, they died of gastrointestinal bleeding due to coagulation factor deficiency. After 1 week on 6 × Met, blood levels of ammonia/homocysteine and hepatic levels of methanethiol/3-methylthiopropionate (a methionine transamination product/methanethiol precursor) became significantly higher in Cth(-/-) mice than in wild-type mice. Although hepatic levels of methionine sulfoxide became higher in 6 × Met-fed wild-type mice and Cth(-/-) mice, those of glutathione, taurine/hypotaurine, and H(2)S became lower and serum levels of homocysteine became much higher in 6 × Met-fed Cth(-/-) mice than in wild-type mice. Thus, transsulfuration plays a critical role in the detoxification of excessive methionine by circumventing aberrant accumulation of its toxic transamination metabolites, including ammonia, methanethiol, and 3-methylthiopropionate, in addition to synthesizing cysteine-derived antioxidants to counteract accumulated pro-oxidants such as methionine sulfoxide and homocysteine.
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Affiliation(s)
- Hidenori Yamada
- Department of Biochemistry, School of Medicine, Keio University, Tokyo 160-8582, Japan
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179
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Ramírez-Torres A, Barceló-Batllori S, Fernández-Vizarra E, Navarro MA, Arnal C, Guillén N, Acín S, Osada J. Proteomics and gene expression analyses of mitochondria from squalene-treated apoE-deficient mice identify short-chain specific acyl-CoA dehydrogenase changes associated with fatty liver amelioration. J Proteomics 2012; 75:2563-75. [DOI: 10.1016/j.jprot.2012.02.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 02/06/2012] [Accepted: 02/20/2012] [Indexed: 02/07/2023]
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180
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Embade N, Fernández-Ramos D, Varela-Rey M, Beraza N, Sini M, de Juan VG, Woodhoo A, Martínez-López N, Rodríguez-Iruretagoyena B, Bustamante FJ, de la Hoz AB, Carracedo A, Xirodimas DP, Rodríguez MS, Lu SC, Mato JM, Martínez-Chantar ML. Murine double minute 2 regulates Hu antigen R stability in human liver and colon cancer through NEDDylation. Hepatology 2012; 55:1237-48. [PMID: 22095636 PMCID: PMC3298572 DOI: 10.1002/hep.24795] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 10/22/2011] [Indexed: 12/14/2022]
Abstract
UNLABELLED Hu antigen R (HuR) is a central RNA-binding protein regulating cell dedifferentiation, proliferation, and survival, which are well-established hallmarks of cancer. HuR is frequently overexpressed in tumors correlating with tumor malignancy, which is in line with a role for HuR in tumorigenesis. However, the precise mechanism leading to changes in HuR expression remains unclear. In the liver, HuR plays a crucial role in hepatocyte proliferation, differentiation, and transformation. Here, we unraveled a novel mean of regulation of HuR expression in hepatocellular carcinoma (HCC) and colon cancer. HuR levels correlate with the abundance of the oncogene, murine double minute 2 (Mdm2), in human HCC and colon cancer metastases. HuR is stabilized by Mdm2-mediated NEDDylation in at least three lysine residues, ensuring its nuclear localization and protection from degradation. CONCLUSION This novel Mdm2/NEDD8/HuR regulatory framework is essential for the malignant transformation of tumor cells, which, in turn, unveils a novel signaling paradigm that is pharmacologically amenable for cancer therapy.
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Affiliation(s)
- Nieves Embade
- 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
| | - 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
| | - Naiara Beraza
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Marcella Sini
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Virginia Gutiérrez de Juan
- 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
| | - Nuria Martínez-López
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | - Begoña Rodríguez-Iruretagoyena
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain
| | | | - Ana Belén de la Hoz
- Midatech Biogune S.L., Technology Park of Bizkaia Ed. 800 48160 Derio Bizkaia, Spain
| | - Arkaitz Carracedo
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd), Technology Park of Bizkaia, 48160-Derio, Bizkaia, Spain,IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain
| | - Dimitris P. Xirodimas
- Centre de Recherche de Biochimie Macromoléculaire - UMR 5237, CNRS, Route de Mende 34 293, Montpellier,Cedex 5, France
| | - Manuel S Rodríguez
- 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, 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
| | - María 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,Contact information: ML Martínez-Chantar, CIC bioGUNE, Technology Park of Bizkaia, 48160 Derio, Bizkaia, Spain. ; Tel: +34-944-061318; Fax: +34-944-061301
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181
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Farrell GC, van Rooyen D, Gan L, Chitturi S. NASH is an Inflammatory Disorder: Pathogenic, Prognostic and Therapeutic Implications. Gut Liver 2012; 6:149-71. [PMID: 22570745 PMCID: PMC3343154 DOI: 10.5009/gnl.2012.6.2.149] [Citation(s) in RCA: 283] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 01/18/2012] [Indexed: 12/12/2022] Open
Abstract
While non-alcoholic fatty liver disease (NAFLD) is highly prevalent (15% to 45%) in modern societies, only 10% to 25% of cases develop hepatic fibrosis leading to cirrhosis, end-stage liver disease or hepatocellular carcinoma. Apart from pre-existing fibrosis, the strongest predictor of fibrotic progression in NAFLD is steatohepatitis or non-alcoholic steatohepatitis (NASH). The critical features other than steatosis are hepatocellular degeneration (ballooning, Mallory hyaline) and mixed inflammatory cell infiltration. While much is understood about the relationship of steatosis to metabolic factors (over-nutrition, insulin resistance, hyperglycemia, metabolic syndrome, hypoadiponectinemia), less is known about inflammatory recruitment, despite its importance for the perpetuation of liver injury and fibrogenesis. In this review, we present evidence that liver inflammation has prognostic significance in NAFLD. We then consider the origins and components of liver inflammation in NASH. Hepatocytes injured by toxic lipid molecules (lipotoxicity) play a central role in the recruitment of innate immunity involving Toll-like receptors (TLRs), Kupffer cells (KCs), lymphocytes and neutrophils and possibly inflammasome. The key pro-inflammatory signaling pathways in NASH are nuclear factor-kappa B (NF-κB) and c-Jun N-terminal kinase (JNK). The downstream effectors include adhesion molecules, chemokines, cytokines and the activation of cell death pathways leading to apoptosis. The upstream activators of NF-κB and JNK are more contentious and may depend on the experimental model used. TLRs are strong contenders. It remains possible that inflammation in NASH originates outside the liver and in the gut microbiota that prime KC/TLR responses, inflamed adipose tissue and circulating inflammatory cells. We briefly review these mechanistic considerations and project their implications for the effective treatment of NASH.
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Affiliation(s)
- Geoffrey C. Farrell
- Gastroenterology and Hepatology Unit, The Canberra Hospital, Australian National University Medical School, Garran, Australia
| | - Derrick van Rooyen
- Gastroenterology and Hepatology Unit, The Canberra Hospital, Australian National University Medical School, Garran, Australia
| | - Lay Gan
- Gastroenterology and Hepatology Unit, The Canberra Hospital, Australian National University Medical School, Garran, Australia
| | - Shivrakumar Chitturi
- Gastroenterology and Hepatology Unit, The Canberra Hospital, Australian National University Medical School, Garran, Australia
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182
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Ueno A, Lazaro R, Wang PY, Higashiyama R, Machida K, Tsukamoto H. Mouse intragastric infusion (iG) model. Nat Protoc 2012; 7:771-81. [PMID: 22461066 DOI: 10.1038/nprot.2012.014] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Direct intragastric delivery of a diet, nutrient or test substance can be achieved in rodents (mice and rats) on a long-term (2-3 months) basis using a chronically implanted gastrostomy catheter and a flow-through swivel system. This rodent intragastric infusion (iG) model has broad applications in research on food intake, gastrointestinal (GI) physiology, GI neuroendocrinology, drug metabolism and toxicity, obesity and liver disease. It achieves maximal control over the rate and pattern of delivery and it can be combined with normal ad libitum feeding of solid diet if so desired. It may be adopted to achieve infusion at other sites of the GI system to test the role of a bypassed GI segment in neuroendocrine physiology, and its use in genetic mouse models facilitates the genetic analysis of a central question under investigation.
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Affiliation(s)
- Akiko Ueno
- Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
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183
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Nagarajan P, Mahesh Kumar MJ, Venkatesan R, Majundar SS, Juyal RC. Genetically modified mouse models for the study of nonalcoholic fatty liver disease. World J Gastroenterol 2012; 18:1141-53. [PMID: 22468076 PMCID: PMC3309902 DOI: 10.3748/wjg.v18.i11.1141] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 09/19/2011] [Accepted: 10/28/2011] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is associated with obesity, insulin resistance, and type 2 diabetes. NAFLD represents a large spectrum of diseases ranging from (1) fatty liver (hepatic steatosis); (2) steatosis with inflammation and necrosis; to (3) cirrhosis. The animal models to study NAFLD/nonalcoholic steatohepatitis (NASH) are extremely useful, as there are still many events to be elucidated in the pathology of NASH. The study of the established animal models has provided many clues in the pathogenesis of steatosis and steatohepatitis, but these remain incompletely understood. The different mouse models can be classified in two large groups. The first one includes genetically modified (transgenic or knockout) mice that spontaneously develop liver disease, and the second one includes mice that acquire the disease after dietary or pharmacological manipulation. Although the molecular mechanism leading to the development of hepatic steatosis in the pathogenesis of NAFLD is complex, genetically modified animal models may be a key for the treatment of NAFLD. Ideal animal models for NASH should closely resemble the pathological characteristics observed in humans. To date, no single animal model has encompassed the full spectrum of human disease progression, but they can imitate particular characteristics of human disease. Therefore, it is important that the researchers choose the appropriate animal model. This review discusses various genetically modified animal models developed and used in research on NAFLD.
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184
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Tomasi ML, Li TWH, Li M, Mato JM, Lu SC. Inhibition of human methionine adenosyltransferase 1A transcription by coding region methylation. J Cell Physiol 2012; 227:1583-91. [PMID: 21678410 DOI: 10.1002/jcp.22875] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Two genes (MAT1A and MAT2A) encode for the essential enzyme methionine adenosyltransferase (MAT). MAT1A is silenced in hepatocellular carcinoma (HCC), and absence of MAT1A leads to spontaneous development of HCC in mice. Previous report correlated promoter methylation to silencing of MAT1A but definitive proof was lacking. Here we investigated the role of methylation in regulating MAT1A expression. There are three MspI/HpaII sites from -1,913 to +160 of the human MAT1A gene (numbered relative to the translational start site) at position -977, +10, and +88. Bisulfite treatment and DNA sequencing, and Southern blot analysis showed that methylation at +10 and +88, but not -977, correlated with lack of MAT1A expression. MAT1A promoter construct methylated at -977, +10 or +88 position has 0.7-fold, 3-fold, and 1.6-fold lower promoter activity, respectively. Methylation at -977 and +10 did not inhibit the promoter more than methylation at +10 alone; while methylation at +10 and +88 reduced promoter activity by 60%. Mutation of +10 and +88 sites also resulted in 40% reduction of promoter activity. Reactivation of MAT1A correlated with demethylation of +10 and +88. In vitro transcription assay showed that methylation or mutation of +10 and +88 sites reduced transcription. In conclusion, our data support the novel finding that methylation of the MAT1A coding region can inhibit gene transcription. This represents a key mechanism for decreased MAT1A expression in HCC and a target for therapy. To our knowledge, this is the first example of coding region methylation inhibiting transcription of a mammalian gene.
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Affiliation(s)
- Maria Lauda Tomasi
- Division of Gastroenterology and Liver Diseases, Keck School of Medicine USC, Los Angeles, California 90033, USA
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185
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Oliva J, Zhong J, Buslon VS, French SW. The effect of SAMe and betaine on Hepa 1-6, C34 and E47 liver cell survival in vitro. Exp Mol Pathol 2012; 92:126-30. [PMID: 22032937 PMCID: PMC3482141 DOI: 10.1016/j.yexmp.2011.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 10/05/2011] [Accepted: 10/08/2011] [Indexed: 01/26/2023]
Abstract
In recent years, methyl one-carbon metabolism has received a great deal of attention because the disruption of methyl balance in a variety of genetically modified mice is associated with the development of various forms of liver injury, namely fatty liver disease and hepatocellular carcinoma (HCC). In addition, patients with liver disease often have an abnormal expression of key genes involved in methionine metabolism as well as elevated serum levels of methionine and homocysteine (Hcy). S-adenosylmethionine (SAMe) has rapidly moved from being a methyl donor to a key metabolite that regulates hepatocyte proliferation, necrosis and differentiation. Biosynthesis of SAMe occurs in all mammalian cells as the first step in methionine catabolism in a reaction catalyzed by methionine adenosyltransferase (MAT). Decreased hepatic SAMe biosynthesis is a consequence of numerous forms of chronic liver injury. In an animal model of chronic liver SAMe deficiency, the liver is predisposed to further injury and develops spontaneous steatohepatitis and HCC. SAMe treatment in experimental animal models of liver injury shows hepatoprotective properties. Meta-analyses also showed that it is effective in the treatment of patients with cholestatic liver diseases. We studied the survival of liver cells treated with SAMe and betaine using Hepa 1-6 and E47/C34 cell lines. We showed that exogenous SAMe decreased the number of Hepa 1-6 and E47/C34 cells, and increased the number of dead cells in vitro. Betaine had no significant effect on the number of surviving cells and the number of dead cells. The combination of both methyl donors significantly increased the survival of liver cells and reduced necrosis, compared to SAMe alone. This study showed the inhibition of the proliferation and increased necrosis in response to SAMe on liver cancer cell lines Hepa 1-6 and C34.
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Affiliation(s)
- Joan Oliva
- Department of Hematology, LA Biomed, Torrance, CA 90502, USA.
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186
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Schröder PC, Fernández-Irigoyen J, Bigaud E, Serna A, Renández-Alcoceba R, Lu SC, Mato JM, Prieto J, Corrales FJ. Proteomic analysis of human hepatoma cells expressing methionine adenosyltransferase I/III: Characterization of DDX3X as a target of S-adenosylmethionine. J Proteomics 2012; 75:2855-68. [PMID: 22270009 DOI: 10.1016/j.jprot.2012.01.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 01/03/2012] [Accepted: 01/05/2012] [Indexed: 02/07/2023]
Abstract
Methionine adenosyltransferase I/III (MATI/III) synthesizes S-adenosylmethionine (SAM) in quiescent hepatocytes. Its activity is compromised in most liver diseases including liver cancer. Since SAM is a driver of hepatocytes fate we have studied the effect of re-expressing MAT1A in hepatoma Huh7 cells using proteomics. MAT1A expression leads to SAM levels close to those found in quiescent hepatocytes and induced apoptosis. Normalization of intracellular SAM induced alteration of 128 proteins identified by 2D-DIGE and gel-free methods, accounting for deregulation of central cellular functions including apoptosis, cell proliferation and survival. Human Dead-box protein 3 (DDX3X), a RNA helicase regulating RNA splicing, export, transcription and translation was down-regulated upon MAT1A expression. Our data support the regulation of DDX3X levels by SAM in a concentration and time dependent manner. Consistently, DDX3X arises as a primary target of SAM and a principal intermediate of its antitumoral effect. Based on the parallelism between SAM and DDX3X along the progression of liver disorders, and the results reported here, it is tempting to suggest that reduced SAM in the liver may lead to DDX3X up-regulation contributing to the pathogenic process and that replenishment of SAM might prove to have beneficial effects, at least in part by reducing DDX3X levels. This article is part of a Special Issue entitled: Proteomics: The clinical link.
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Affiliation(s)
- Paul C Schröder
- Division of Hepatology and Gene Therapy, CIMA, University of Navarra, 31008 Pamplona, Spain
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187
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Moro S, Chipman JK, Antczak P, Turan N, Dekant W, Falciani F, Mally A. Identification and Pathway Mapping of Furan Target Proteins Reveal Mitochondrial Energy Production and Redox Regulation as Critical Targets of Furan Toxicity. Toxicol Sci 2012; 126:336-52. [DOI: 10.1093/toxsci/kfs005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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188
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Inhibition of betaine-homocysteine S-methyltransferase in rats causes hyperhomocysteinemia and reduces liver cystathionine β-synthase activity and methylation capacity. Nutr Res 2012; 31:563-71. [PMID: 21840473 DOI: 10.1016/j.nutres.2011.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/17/2011] [Accepted: 06/18/2011] [Indexed: 11/21/2022]
Abstract
Methylation of homocysteine (Hcy) by betaine-Hcy S-methyltransferase (BHMT) produces methionine, which is required for S-adenosylmethionine (SAM) synthesis. We have recently shown that short-term dietary intake of S-(Δ-carboxybutyl)-dl-Hcy (D,L-CBHcy), a potent and specific inhibitor of BHMT, significantly decreases liver BHMT activity and SAM concentrations but does not have an adverse affect on liver histopathology, plasma markers of liver damage, or DNA methylation in rats. The present study was designed to investigate the hypothesis that BHMT is required to maintain normal liver and plasma amino acid and glutathione profiles, and liver SAM and lipid accumulation. Rats were fed an adequate (4.5 g/kg methionine and 3.7 g/kg cystine), cysteine-devoid (4.5 g/kg methionine and 0 g/kg cystine), or methionine-deficient (1.5 g/kg methionine and 3.7 g/kg cystine) diet either with or without L-CBHcy for 3 or 14 days. All rats fed L-CBHcy had increased total plasma Hcy (2- to 5-fold) and reduced liver BHMT activity (>90%) and SAM concentrations (>40%). S-(Δ-carboxybutyl)-l-Hcy treatment slightly reduced liver glutathione levels in rats fed the adequate or cysteine-devoid diet for 14 days. Rats fed the methionine-deficient diet with L-CBHcy developed fatty liver. Liver cystathionine β-synthase activity was reduced in all L-CBHcy-treated animals, and the effect was exacerbated as time on the L-CBHcy diet increased. Our data indicate that BHMT activity is required to maintain adequate levels of liver SAM and low levels of total plasma Hcy and might be critical for liver glutathione and triglyceride homeostasis under some dietary conditions.
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189
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Conde-Vancells J, Falcon-Perez JM. Isolation of urinary exosomes from animal models to unravel noninvasive disease biomarkers. Methods Mol Biol 2012; 909:321-40. [PMID: 22903725 DOI: 10.1007/978-1-61779-959-4_21] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In the last years, disease biomarker discovery has highly evolved thanks to the application of high--throughput technologies such as proteomics. However, due to the elevated complexity and abundance of some of the proteins in the samples the analysis of subcellular compartments has been revealed to be fundamental in order to identify underrepresented clinically relevant proteins. In this sense, extracellular microvesicles including exosomes that are present in different body fluids constitute a suitable and convenient subcellular compartment to identify disease biomarkers. On the other hand, animal models offer numerous advantages over human samples in order to accelerate the identification of candidate biomarkers. In this chapter we provide a detailed methodology to purify and analyze urinary exosomes that can be applied to the study of different diseases that have good animal models.
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190
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Gomez-Santos L, Vazquez-Chantada M, Mato JM, Martinez-Chantar ML. SAMe and HuR in liver physiology: usefulness of stem cells in hepatic differentiation research. Methods Mol Biol 2012; 826:133-49. [PMID: 22167646 DOI: 10.1007/978-1-61779-468-1_12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
S-Adenosylmethionine, abbreviated as SAM, SAMe or AdoMet, is the principal methyl group donor in the mammalian cell and the first step metabolite of the methionine cycle, being synthesized by MAT (methionine adenosyltransferase) from methionine and ATP. About 60 years after its identification, SAMe is admitted as a key hepatic regulator whose level needs to be maintained within a specific range in order to avoid liver damage. Recently, in vitro and in vivo studies have demonstrated the regulatory role of SAMe in HGF (hepatocyte growth factor)-mediated hepatocyte proliferation through a mechanism that implicates the activation of the non-canonical LKB1/AMPK/eNOS cascade and HuR function. Regarding hepatic differentiation, cellular SAMe content varies depending on the status of the cell, being lower in immature than in adult hepatocytes. This finding suggests a SAMe regulatory effect also in this cellular process, which very recently was reported and related to HuR activity. Although in the last years this and other discoveries contributed to throw light into the tangle of regulatory mechanisms that govern this complex process, an overall understanding is still a challenge. For this purpose, the in vitro hepatic differentiation culture systems by using stem cells or fetal hepatoblasts are considered as valuable tools which, in combination with the methods used in current days to elucidate cell signaling pathways, surely will help to clear up this question.
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Affiliation(s)
- Laura Gomez-Santos
- Metabolomics Unit, CIC bioGUNE, Technology Park of Bizkaia, Bizkaia, Basque Country, Spain.
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191
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Cano A, Buqué X, Martínez-Uña M, Aurrekoetxea I, Menor A, García-Rodriguez JL, Lu SC, Martínez-Chantar ML, Mato JM, Ochoa B, Aspichueta P. Methionine adenosyltransferase 1A gene deletion disrupts hepatic very low-density lipoprotein assembly in mice. Hepatology 2011; 54:1975-86. [PMID: 21837751 PMCID: PMC3222787 DOI: 10.1002/hep.24607] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
UNLABELLED Very low-density lipoprotein (VLDL) secretion provides a mechanism to export triglycerides (TG) from the liver to peripheral tissues, maintaining lipid homeostasis. In nonalcoholic fatty liver disease (NAFLD), VLDL secretion disturbances are unclear. Methionine adenosyltransferase (MAT) is responsible for S-adenosylmethionine (SAMe) synthesis and MAT I and III are the products of the MAT1A gene. Deficient MAT I and III activities and SAMe content in the liver have been associated with NAFLD, but whether MAT1A is required for normal VLDL assembly remains unknown. We investigated the role of MAT1A on VLDL assembly in two metabolic contexts: in 3-month-old MAT1A-knockout mice (3-KO), with no signs of liver injury, and in 8-month-old MAT1A-knockout mice (8-KO), harboring nonalcoholic steatohepatitis. In 3-KO mouse liver, there is a potent effect of MAT1A deletion on lipid handling, decreasing mobilization of TG stores, TG secretion in VLDL and phosphatidylcholine synthesis via phosphatidylethanolamine N-methyltransferase. MAT1A deletion also increased VLDL-apolipoprotein B secretion, leading to small, lipid-poor VLDL particles. Administration of SAMe to 3-KO mice for 7 days recovered crucial altered processes in VLDL assembly and features of the secreted lipoproteins. The unfolded protein response was activated in 8-KO mouse liver, in which TG accumulated and the phosphatidylcholine-to-phosphatidylethanolamine ratio was reduced in the endoplasmic reticulum, whereas secretion of TG and apolipoprotein B in VLDL was increased and the VLDL physical characteristics resembled that in 3-KO mice. MAT1A deletion also altered plasma lipid homeostasis, with an increase in lipid transport in low-density lipoprotein subclasses and decrease in high-density lipoprotein subclasses. CONCLUSION MAT1A is required for normal VLDL assembly and plasma lipid homeostasis in mice. Impaired VLDL synthesis, mainly due to SAMe deficiency, contributes to NAFLD development in MAT1A-KO mice.
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Affiliation(s)
- Ainara Cano
- Department of Physiology, University of the Basque Country Medical School, Bilbao, Spain
| | - Xabier Buqué
- Department of Physiology, University of the Basque Country Medical School, Bilbao, Spain
| | - Maite Martínez-Uña
- Department of Physiology, University of the Basque Country Medical School, Bilbao, Spain
| | - Igor Aurrekoetxea
- Department of Physiology, University of the Basque Country Medical School, Bilbao, Spain
| | - Ariane Menor
- Department of Physiology, University of the Basque Country Medical School, Bilbao, Spain
| | - Juan L García-Rodriguez
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Technology Park of Bizkaia, 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 Digestivas (CIBERehd), Technology Park of Bizkaia, Spain
| | - José M. Mato
- CIC bioGUNE, Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Technology Park of Bizkaia, Spain
| | - Begoña Ochoa
- Department of Physiology, University of the Basque Country Medical School, Bilbao, Spain
| | - Patricia Aspichueta
- Department of Physiology, University of the Basque Country Medical School, Bilbao, Spain,Corresponding author: Patricia Aspichueta, Department of Physiology, University of the Basque Country Medical School, Sarriena s/n, 48940 Leioa, Spain. Phone: +34 946012896; Fax: +34 946015662;
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Walker AK, Jacobs RL, Watts JL, Rottiers V, Jiang K, Finnegan DM, Shioda T, Hansen M, Yang F, Niebergall LJ, Vance DE, Tzoneva M, Hart AC, Näär AM. A conserved SREBP-1/phosphatidylcholine feedback circuit regulates lipogenesis in metazoans. Cell 2011; 147:840-52. [PMID: 22035958 DOI: 10.1016/j.cell.2011.09.045] [Citation(s) in RCA: 318] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Revised: 06/14/2011] [Accepted: 09/19/2011] [Indexed: 12/17/2022]
Abstract
Sterol regulatory element-binding proteins (SREBPs) activate genes involved in the synthesis and trafficking of cholesterol and other lipids and are critical for maintaining lipid homeostasis. Aberrant SREBP activity, however, can contribute to obesity, fatty liver disease, and insulin resistance, hallmarks of metabolic syndrome. Our studies identify a conserved regulatory circuit in which SREBP-1 controls genes in the one-carbon cycle, which produces the methyl donor S-adenosylmethionine (SAMe). Methylation is critical for the synthesis of phosphatidylcholine (PC), a major membrane component, and we find that blocking SAMe or PC synthesis in C. elegans, mouse liver, and human cells causes elevated SREBP-1-dependent transcription and lipid droplet accumulation. Distinct from negative regulation of SREBP-2 by cholesterol, our data suggest a feedback mechanism whereby maturation of nuclear, transcriptionally active SREBP-1 is controlled by levels of PC. Thus, nutritional or genetic conditions limiting SAMe or PC production may activate SREBP-1, contributing to human metabolic disorders.
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Affiliation(s)
- Amy K Walker
- Massachusetts General Hospital Cancer Center, Building 149, 13th Street, Charlestown, MA 02129, USA.
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193
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Pajares MA, Markham GD. Methionine adenosyltransferase (s-adenosylmethionine synthetase). ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2011; 78:449-521. [PMID: 22220481 DOI: 10.1002/9781118105771.ch11] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- María A Pajares
- Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM), Madrid Spain
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194
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Methionine and protein metabolism in non-alcoholic steatohepatitis: evidence for lower rate of transmethylation of methionine. Clin Sci (Lond) 2011; 121:179-89. [PMID: 21446920 DOI: 10.1042/cs20110060] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepatic metabolism of methionine is the source of cysteine, the precursor of glutathione, the major intracellular antioxidant in the body. Methionine also is the immediate precursor of SAM (S-adenosylmethionine) the key methyl donor for phosphatidylcholine synthesis required for the export of VLDL (very-low-density lipoprotein) triacylglycerols (triglycerides) from the liver. We have examined the kinetics of methionine, its transmethylation and trans-sulfuration with estimates of whole body rate of protein turnover and urea synthesis in clinically stable biopsy-confirmed subjects with NASH (non-alcoholic steatohepatitis). Subjects with NASH were more insulin-resistant and had significantly higher plasma concentrations of usCRP (ultrasensitive C-reactive protein), TNFα (tumour necrosis factor α) and other inflammatory cytokines. There was no significant effect of insulin resistance and NASH on whole body rate of protein turnover [phenylalanine Ra (rate of appearance)] and on the rate of urea synthesis. The rates of methylation of homocysteine and transmethylation of methionine were significantly lower in NASH compared with controls. There was no difference in the rate of trans-sulfuration of methionine between the two groups. Enteric mixed nutrient load resulted in a significant increase in all the measured parameters of methionine kinetics. Heterozygosity for MTHFR (5,10-methylene-tetrahydrofolate reductase) (677C→T) did not have an impact on methionine metabolism. We speculate that, as a result of oxidant stress possibly due to high fatty acid oxidation, the activity of methionine adenosyltransferase is attenuated resulting in a lower rate of transmethylation of methionine and of SAM synthesis. These results are the first evidence for perturbed metabolism of methionine in NASH in humans and provide a rationale for the development of targeted intervention strategies.
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195
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Fernández-Domínguez I, Echevarria-Uraga JJ, Gómez N, Luka Z, Wagner C, Lu SC, Mato JM, Martínez-Chantar ML, Rodríguez-Cuesta J. High-frequency ultrasound imaging for longitudinal evaluation of non-alcoholic fatty liver disease progression in mice. ULTRASOUND IN MEDICINE & BIOLOGY 2011; 37:1161-9. [PMID: 21645964 PMCID: PMC3118979 DOI: 10.1016/j.ultrasmedbio.2011.04.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 04/11/2011] [Accepted: 04/21/2011] [Indexed: 05/13/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of hepatic damage in developed countries. For this reason, mouse models of NAFLD have been developed to show progression of the disease because it perfectly resembles the human pathology. Here we show that diagnostic high-frequency ultrasound imaging (US) may be used as an effective method for monitoring the progression of liver disease, from steatosis to hepatocellular carcinoma in the methionine adenosyl transferase and glycine N-methyltransferase-deficient mice models. US reliably detected murine liver lesions associated with NAFLD in the two mice strains tested, with excellent agreement among US images, gross pathology and histological sections. Our results suggest US as a relevant approach for the study of NAFLD in mice, with interesting technical and therapeutic implications.
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196
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A signature of six genes highlights defects on cell growth and specific metabolic pathways in murine and human hepatocellular carcinoma. Funct Integr Genomics 2011; 11:419-29. [PMID: 21562899 DOI: 10.1007/s10142-011-0230-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 04/19/2011] [Accepted: 04/21/2011] [Indexed: 01/11/2023]
Abstract
Hepatocellular carcinoma (HCC) represents a major health problem as it afflicts an increasing number of patients worldwide. Albeit most of the risk factors for HCC are known, this is a deadly syndrome with a life expectancy at the time of diagnosis of less than 1 year. Definition of the molecular principles governing the neoplastic transformation of the liver is an urgent need to facilitate the clinical management of patients, based on innovative methods to detect the disease in its early stages and on more efficient therapies. In the present study, we have combined the analysis of a murine model and human samples of HCC to identify genes differentially expressed early in the process of hepatocarcinogenesis, using a microarray-based approach. Expression of 190 genes was impaired in murine HCC from which 65 were further validated by low-density array real-time polymerase chain reaction (RT-PCR). The expression of the best 45 genes was then investigated in human samples resulting in 18 genes in which expression was significantly modified in HCC. Among them, JUN, methionine adenosyltransferase 1A and 2A, phosphoglucomutase 1, and acyl CoA dehydrogenase short/branched chain indicate defective cell proliferation as well as one carbon pathway, glucose and fatty acid metabolism, both in HCC and cirrhotic liver, a well-known preneoplastic condition. These alterations were further confirmed in public transcriptomic datasets from other authors. In addition, vasodilator-stimulated phosphoprotein, an actin-associated protein involved in cytoskeleton remodeling, was also found to be increased in the liver and serum of cirrhotic and HCC patients. In addition to revealing the impairment of central metabolic pathways for liver homeostasis, further studies may probe the potential value of the reported genes for the early detection of HCC.
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197
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Role of methionine adenosyltransferase genes in hepatocarcinogenesis. Cancers (Basel) 2011; 3:1480-97. [PMID: 24212770 PMCID: PMC3757373 DOI: 10.3390/cancers3021480] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 01/27/2011] [Accepted: 01/30/2011] [Indexed: 12/19/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver. Detection of HCC can be difficult, as most of the patients who develop this tumor have no symptoms other than those related to their longstanding liver disease. There is an urgent need to understand the molecular mechanisms that are responsible for the development of this disease so that appropriate therapies can be designed. Methionine adenosyltransferase (MAT) is an essential enzyme required for the biosynthesis of S-adenosylmethionine (AdoMet), an important methyl donor in the cell. Alterations in the expression of MAT genes and a decline in AdoMet biosynthesis are known to be associated with liver injury, cirrhosis and HCC. This review focuses on the role of MAT genes in HCC development and the scope for therapeutic strategies using these genes.
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198
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Mudd SH. Hypermethioninemias of genetic and non-genetic origin: A review. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2011; 157C:3-32. [PMID: 21308989 DOI: 10.1002/ajmg.c.30293] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This review covers briefly the major conditions, genetic and non-genetic, sometimes leading to abnormally elevated methionine, with emphasis on recent developments. A major aim is to assist in the differential diagnosis of hypermethioninemia. The genetic conditions are: (1) Homocystinuria due to cystathionine β-synthase (CBS) deficiency. At least 150 different mutations in the CBS gene have been identified since this deficiency was established in 1964. Hypermethioninemia is due chiefly to remethylation of the accumulated homocysteine. (2) Deficient activity of methionine adenosyltransferases I and III (MAT I/III), the isoenzymes the catalytic subunit of which are encoded by MAT1A. Methionine accumulates because its conversion to S-adenosylmethionine (AdoMet) is impaired. (3) Glycine N-methyltrasferase (GNMT) deficiency. Disruption of a quantitatively major pathway for AdoMet disposal leads to AdoMet accumulation with secondary down-regulation of methionine flux into AdoMet. (4) S-adenosylhomocysteine (AdoHcy) hydrolase (AHCY) deficiency. Not being catabolized normally, AdoHcy accumulates and inhibits many AdoMet-dependent methyltransferases, producing accumulation of AdoMet and, thereby, hypermethioninemia. (5) Citrin deficiency, found chiefly in Asian countries. Lack of this mitochondrial aspartate-glutamate transporter may produce (usually transient) hypermethioninemia, the immediate cause of which remains uncertain. (6) Fumarylacetoacetate hydrolase (FAH) deficiency (tyrosinemia type I) may lead to hypermethioninemia secondary either to liver damage and/or to accumulation of fumarylacetoacetate, an inhibitor of the high K(m) MAT. Additional possible genetic causes of hypermethioninemia accompanied by elevations of plasma AdoMet include mitochondrial disorders (the specificity and frequency of which remain to be elucidated). Non-genetic conditions include: (a) Liver disease, which may cause hypermethioninemia, mild, or severe. (b) Low-birth-weight and/or prematurity which may cause transient hypermethioninemia. (c) Ingestion of relatively large amounts of methionine which, even in full-term, normal-birth-weight babies may cause hypermethioninemia.
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Affiliation(s)
- S Harvey Mudd
- Laboratory of Molecular Biology, National Institute of Mental Health, Bethesda, MD, USA.
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199
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Ko KS, Tomasi ML, Iglesias-Ara A, French BA, French SW, Ramani K, Lozano JJ, Oh P, He L, Stiles BL, Li TWH, Yang H, Martínez-Chantar ML, Mato JM, Lu SC. Liver-specific deletion of prohibitin 1 results in spontaneous liver injury, fibrosis, and hepatocellular carcinoma in mice. Hepatology 2010; 52:2096-108. [PMID: 20890892 PMCID: PMC3005187 DOI: 10.1002/hep.23919] [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: 04/27/2010] [Accepted: 08/06/2010] [Indexed: 12/11/2022]
Abstract
UNLABELLED Prohibitin 1 (PHB1) is a highly conserved, ubiquitously expressed protein that participates in diverse processes including mitochondrial chaperone, growth and apoptosis. The role of PHB1 in vivo is unclear and whether it is a tumor suppressor is controversial. Mice lacking methionine adenosyltransferase 1A (MAT1A) have reduced PHB1 expression, impaired mitochondrial function, and spontaneously develop hepatocellular carcinoma (HCC). To see if reduced PHB1 expression contributes to the Mat1a knockout (KO) phenotype, we generated liver-specific Phb1 KO mice. Expression was determined at the messenger RNA and protein levels. PHB1 expression in cells was varied by small interfering RNA or overexpression. At 3 weeks, KO mice exhibit biochemical and histologic liver injury. Immunohistochemistry revealed apoptosis, proliferation, oxidative stress, fibrosis, bile duct epithelial metaplasia, hepatocyte dysplasia, and increased staining for stem cell and preneoplastic markers. Mitochondria are swollen and many have no discernible cristae. Differential gene expression revealed that genes associated with proliferation, malignant transformation, and liver fibrosis are highly up-regulated. From 20 weeks on, KO mice have multiple liver nodules and from 35 to 46 weeks, 38% have multifocal HCC. PHB1 protein levels were higher in normal human hepatocytes compared to human HCC cell lines Huh-7 and HepG2. Knockdown of PHB1 in murine nontransformed AML12 cells (normal mouse hepatocyte cell line) raised cyclin D1 expression, increased E2F transcription factor binding to cyclin D1 promoter, and proliferation. The opposite occurred with PHB1 overexpression. Knockdown or overexpression of PHB1 in Huh-7 cells did not affect proliferation significantly or sensitize cells to sorafenib-induced apoptosis. CONCLUSION Hepatocyte-specific PHB1 deficiency results in marked liver injury, oxidative stress, and fibrosis with development of HCC by 8 months. These results support PHB1 as a tumor suppressor in hepatocytes.
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Affiliation(s)
- Kwang Suk Ko
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, CA 90033
| | - Maria Lauda Tomasi
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, CA 90033
| | - Ainhoa Iglesias-Ara
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, CA 90033
| | - Barbara A French
- Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine USC, Los Angeles, CA 90033
,Department of Pathology, Harbor-UCLA Medical Center, Torrance, CA 90509
| | - Samuel W. French
- Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine USC, Los Angeles, CA 90033
,Department of Pathology, Harbor-UCLA Medical Center, Torrance, CA 90509
| | - Komal Ramani
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, CA 90033
,Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine USC, Los Angeles, CA 90033
| | - Juan José Lozano
- Plataforma de Bioinformatica, Center for Cooperative Research in Biosciences, CIBERehd, Hospital Clinic, Barcelona, Spain
| | - Pilsoo Oh
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, CA 90033
| | - Lina He
- Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089
| | - Bangyan L. Stiles
- Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089
| | - Tony W. H. Li
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, CA 90033
| | - Heping Yang
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, CA 90033
| | - M Luz Martínez-Chantar
- CIC Biogune, Center for Cooperative Research in Biosciences, CIBERehd, Parque Tecnológico de Bizkaia, Derio, Bizkaia
| | - José M. Mato
- CIC Biogune, Center for Cooperative Research in Biosciences, CIBERehd, Parque Tecnológico de Bizkaia, Derio, Bizkaia
| | - Shelly C. Lu
- Division of Gastroenterology and Liver Diseases, USC Research Center for Liver Diseases, Keck School of Medicine USC, Los Angeles, CA 90033
,Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine USC, Los Angeles, CA 90033
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200
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Yamaji S, Droggiti A, Lu SC, Martinez-Chantar ML, Warner A, Varela-Rey M. S-Adenosylmethionine regulates connexins sub-types expressed by hepatocytes. Eur J Cell Biol 2010; 90:312-22. [PMID: 21093098 DOI: 10.1016/j.ejcb.2010.09.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Revised: 09/20/2010] [Accepted: 09/20/2010] [Indexed: 01/01/2023] Open
Abstract
Intercellular communication via GAP Junctions plays an important role in tissue homeostasis, apoptosis, carcinogenesis, cell proliferation and differentiation. Hepatocyte connexins (Cx) 26 and 32 levels are decreased during the de-differentiation process of primary hepatocytes in culture, a situation that is also characterized by a decrease in S-Adenosylmethionine (SAMe) levels. In this current study, we show that SAMe supplementation in cultured hepatocytes every 12h, leads to an up-regulation of Cx26 and 32 mRNA and protein levels and blocks culture-induced Cx43 expression, although it failed to increase Cx26 and 32 membrane localization and GAP junction intracellular communication. SAMe reduced nuclear β-catenin accumulation, which is known to stimulate the TCF/LEF-dependent gene transcription of Cx43. Moreover SAMe-induced reduction in Cx43 and β-catenin was prevented by the proteasome inhibitor MG132, and was not mediated by GSK3 activity. SAMe, and its metabolite 5'-methylthioadenosine (MTA) increased Cx26 mRNA in a process partially mediated by Adenosine A(2A) receptors but independent of PKA. Finally livers from MAT1A knockout mice, characterized by low hepatic SAMe levels, express higher Cx43 and lower Cx26 and 32 protein levels than control mice. These results suggest that SAMe maintains a characteristic expression pattern of the different Cxs in hepatocytes by differentially regulating their levels.
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Affiliation(s)
- Sachie Yamaji
- Department of Cell and Developmental Biology (formerly Anatomy and Developmental Biology), University College London, London, UK
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