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Yang H, You L, Wang Z, Yang L, Wang X, Wu W, Zhi H, Rong G, Sheng Y, Liu X, Liu L. Bile duct ligation elevates 5-HT levels in cerebral cortex of rats partly due to impairment of brain UGT1A6 expression and activity via ammonia accumulation. Redox Biol 2024; 69:103019. [PMID: 38163420 PMCID: PMC10794929 DOI: 10.1016/j.redox.2023.103019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 12/19/2023] [Accepted: 12/27/2023] [Indexed: 01/03/2024] Open
Abstract
Hepatic encephalopathy (HE) is often associated with endogenous serotonin (5-HT) disorders. However, the reason for elevated brain 5-HT levels due to liver failure remains unclear. This study aimed to investigate the mechanism by which liver failure increases brain 5-HT levels and the role in behavioral abnormalities in HE. Using bile duct ligation (BDL) rats as a HE model, we verified the elevated 5-HT levels in the cortex but not in the hippocampus and striatum, and found that this cortical 5-HT overload may be caused by BDL-mediated inhibition of UDP-glucuronosyltransferase 1A6 (UGT1A6) expression and activity in the cortex. The intraventricular injection of the UGT1A6 inhibitor diclofenac into rats demonstrated that the inhibition of brain UGT1A6 activity significantly increased cerebral 5-HT levels and induced HE-like behaviors. Co-immunofluorescence experiments demonstrated that UGT1A6 is primarily expressed in astrocytes. In vitro studies confirmed that NH4Cl activates the ROS-ERK pathway to downregulate UGT1A6 activity and expression in U251 cells, which can be reversed by the oxidative stress antagonist N-acetyl-l-cysteine and the ERK inhibitor U0126. Silencing Hepatocyte Nuclear Factor 4α (HNF4α) suppressed UGT1A6 expression whilst overexpressing HNF4α increased Ugt1a6 promotor activity. Meanwhile, both NH4Cl and the ERK activator TBHQ downregulated HNF4α and UGT1A6 expression. In the cortex of hyperammonemic rats, we also found activation of the ROS-ERK pathway, decreases in HNF4α and UGT1A6 expression, and increases in brain 5-HT content. These results prove that the ammonia-mediated ROS-ERK pathway activation inhibits HNF4α expression to downregulate UGT1A6 expression and activity, thereby increasing cerebral 5-HT content and inducing manic-like HE symptoms. This is the first study to reveal the mechanism of elevated cortical 5-HT concentration in a state of liver failure and elucidate its association with manic-like behaviors in HE.
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Affiliation(s)
- Hanyu Yang
- State Key Laboratory of Natural Medicines, Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, 210009, Nanjing, China; Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Linjun You
- Center for New Drug Safety Evaluation and Research, China Pharmaceutical University, 210009, Nanjing, China
| | - Zhongyan Wang
- Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Lu Yang
- Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Xun Wang
- Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Wenhan Wu
- Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Hao Zhi
- Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Guangmei Rong
- Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Yun Sheng
- Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Xiaodong Liu
- State Key Laboratory of Natural Medicines, Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, 210009, Nanjing, China; Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China.
| | - Li Liu
- State Key Laboratory of Natural Medicines, Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, 210009, Nanjing, China; Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China.
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Overview of Nutraceuticals and Cardiometabolic Diseases following Socio-Economic Analysis. ENDOCRINES 2022. [DOI: 10.3390/endocrines3020023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The importance of functional food and nutraceutical products to deal with cardiometabolic diseases (CMDs) and metabolic syndrome (MetS) has gained attention in the past few years. The aim of this narrative review is to highlight the potential and effectiveness of nutraceutical in the improvement of CMDs and MetS biomarkers, alongside their burden of disease and economic health expenditure. A science database search was conducted between May and June 2021. A total of 35 studies were included in this paper. We included male and female subjects, children, and adults, in good health or with cardiovascular or metabolic disease. CMDs and MetS have gradually become worldwide health problems, becoming two of the major causes of morbidity and mortality in western countries. The results indicate a positive link between daily consumption of nutraceutical products and an improvement in cardiometabolic and anthropometric biomarkers. In this paper we included a wide range of nutraceutical products. Most of them showed promising data, indicating that nutraceuticals could provide a new therapeutic treatment to reduce prevalence and pharmaceutical expenditures attributed to CMDs and MetS. Unfortunately, there is a huge vacuum of data on nutraceutical usage, savings, and burden reduction. Therefore, further clinical and pharmaco-economic research in the field is highly required.
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Guo Y, Zhao J, Huang R, Xu T, Zhou K, Zheng L. Scalable Dual-Fluorescence Assay for Functional Interpretation of HNF-4α Missense Variants. Front Endocrinol (Lausanne) 2022; 13:812747. [PMID: 35237236 PMCID: PMC8883583 DOI: 10.3389/fendo.2022.812747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 01/17/2022] [Indexed: 11/15/2022] Open
Abstract
AIM The study aimed to develop a scalable dual-fluorescence assay in cells to enable the functional interpretation of HNF-4α missense variants identified in exome sequencing, which can be used to guide clinical diagnosis. METHODS Using mOrange2 and GFP fluorescence proteins to track the expression of HNF-4α (HNF-4α-mOrange2) and reporter activity under the control of the HNF-1α promoter (pHNF1A-GFP), respectively, we designed a dual-fluorescence assay to evaluate the expression level, cellular localization, and transcriptional function of HNF-4α simultaneously in live cells. To assess the scalable characteristic of the assay, a small library containing five previously reported mutations and wild-type HNF-4α was constructed. Cells infected with this library were sorted into different populations through fluorescence-activated cell sorting (FACS) according to the transcription activity and expression abundance. Cloning and Sanger sequencing were used to detect the mutations of the different groups. High content screening (HCS) assay was used for the validation of individual mutants in the function and expression point of view. RESULTS HNF-4α-mOrange2 exhibited nuclear localization and transactivation capability on the HNF-1α promoter as physical HNF-4α does. The expression of HNF-4α-mOrange2 shows a 6-fold induction of GFP expression compared to the control without HNF-4α-mOrange2, which was significantly abolished by the known loss-of-function mutant M373R. The different performances of wild-type and mutant M373R made them distinguishable in the FACS system, empowering the scalable capability of this assay for classifying large numbers of variants combining functional stratification and sequencing. Further application of the assay in the small library showed that three cell populations were seen grouped as Normal (same transactivation as wild type), Reducedexp_nor (reduced transactivation with normal or higher expression), and Reducedexp_low (reduced transactivation with lower expression). Subsequently, Sanger sequencing showed that wild-type HNF-4α was in the Normal group, two mutations (M373R and G79C) were enriched in the Reducedexp_nor group, and three mutations (C115S, L272P, and F83C) belonged to the Reducedexp_low group. These results were validated by further imaging data using HCS assay for individual mutation. CONCLUSIONS Our study proposes a scalable and informative approach for the characterization of the variants in HNF-4α genes in a quantitative and high-throughput manner.
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Affiliation(s)
- Yiming Guo
- College of Life Sciences, the University of Chinese Academy of Sciences, Beijing, China
| | - Jing Zhao
- College of Life Sciences, the University of Chinese Academy of Sciences, Beijing, China
| | | | - Tao Xu
- College of Life Sciences, the University of Chinese Academy of Sciences, Beijing, China
- Guangzhou Laboratory, Guangzhou, China
- Key Laboratory of RNA Biology, Center for Big Data Research in Health, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
- *Correspondence: Li Zheng, ; Kaixin Zhou, ; Tao Xu,
| | - Kaixin Zhou
- College of Life Sciences, the University of Chinese Academy of Sciences, Beijing, China
- Guangzhou Laboratory, Guangzhou, China
- *Correspondence: Li Zheng, ; Kaixin Zhou, ; Tao Xu,
| | - Li Zheng
- Key Laboratory of RNA Biology, Center for Big Data Research in Health, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- *Correspondence: Li Zheng, ; Kaixin Zhou, ; Tao Xu,
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Migdał M, Tralle E, Nahia KA, Bugajski Ł, Kędzierska KZ, Garbicz F, Piwocka K, Winata CL, Pawlak M. Multi-omics analyses of early liver injury reveals cell-type-specific transcriptional and epigenomic shift. BMC Genomics 2021; 22:904. [PMID: 34920711 PMCID: PMC8684102 DOI: 10.1186/s12864-021-08173-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 11/10/2021] [Indexed: 12/20/2022] Open
Abstract
Background Liver fibrosis is a wound-healing response to tissue injury and inflammation hallmarked by the extracellular matrix (ECM) protein deposition in the liver parenchyma and tissue remodelling. Different cell types of the liver are known to play distinct roles in liver injury response. Hepatocytes and liver endothelial cells receive molecular signals indicating tissue injury and activate hepatic stellate cells which produce ECM proteins upon their activation. Despite the growing knowledge on the molecular mechanism underlying hepatic fibrosis in general, the cell-type-specific gene regulatory network associated with the initial response to hepatotoxic injury is still poorly characterized. Results In this study, we used thioacetamide (TAA) to induce hepatic injury in adult zebrafish. We isolated three major liver cell types - hepatocytes, endothelial cells and hepatic stellate cells - and identified cell-type-specific chromatin accessibility and transcriptional changes in an early stage of liver injury. We found that TAA induced transcriptional shifts in all three cell types hallmarked by significant alterations in the expression of genes related to fatty acid and carbohydrate metabolism, as well as immune response-associated and vascular-specific genes. Interestingly, liver endothelial cells exhibit the most pronounced response to liver injury at the transcriptome and chromatin level, hallmarked by the loss of their angiogenic phenotype. Conclusion Our results uncovered cell-type-specific transcriptome and epigenome responses to early stage liver injury, which provide valuable insights into understanding the molecular mechanism implicated in the early response of the liver to pro-fibrotic signals. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-08173-1.
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Asano K, Tsukada A, Yanagisawa Y, Higuchi M, Takagi K, Ono M, Tanaka T, Tomita K, Yamada K. Melatonin stimulates transcription of the rat phosphoenolpyruvate carboxykinase gene in hepatic cells. FEBS Open Bio 2020; 10:2712-2721. [PMID: 33070478 PMCID: PMC7714082 DOI: 10.1002/2211-5463.13007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/24/2020] [Accepted: 10/16/2020] [Indexed: 12/22/2022] Open
Abstract
Melatonin plays physiological roles in various critical processes, including circadian rhythms, oxidative stress defenses, anti-inflammation responses, and immunity; however, the current understanding of the role of melatonin in hepatic glucose metabolism is limited. In this study, we examined whether melatonin affects gene expression of the key gluconeogenic enzyme, phosphoenolpyruvate carboxykinase (PEPCK). We found that melatonin treatment increased PEPCK mRNA levels in rat highly differentiated hepatoma (H4IIE) cells and primary cultured hepatocytes. In addition, we found that melatonin induction was synergistically enhanced by dexamethasone, whereas it was dominantly inhibited by insulin. We also report that the effect of melatonin was blocked by inhibitors of mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/ERK), RNA polymerase II, and protein synthesis. Furthermore, the phosphorylated (active) forms of ERK1 and ERK2 (ERK1/2) increased 15 min after melatonin treatment. We performed luciferase reporter assays to show that melatonin specifically stimulated promoter activity of the PEPCK gene. Additional reporter analysis using 5'-deleted constructs revealed that the regulatory regions responsive to melatonin mapped to two nucleotide regions, one between -467 and -398 nucleotides and the other between -128 and +69 nucleotides, of the rat PEPCK gene. Thus, we conclude that melatonin induces PEPCK gene expression via the ERK1/2 pathway at the transcriptional level, and that induction requires de novo protein synthesis.
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Affiliation(s)
- Kosuke Asano
- Department of Health and Nutritional Science, Faculty of Human Health Science, Matsumoto University, Matsumoto, Japan
| | - Akiko Tsukada
- Department of Health and Nutritional Science, Faculty of Human Health Science, Matsumoto University, Matsumoto, Japan
| | - Yuki Yanagisawa
- Matsumoto University Graduate School of Health Science, Matsumoto, Japan
| | - Mariko Higuchi
- Matsumoto University Graduate School of Health Science, Matsumoto, Japan
| | - Katsuhiro Takagi
- Department of Health and Nutritional Science, Faculty of Human Health Science, Matsumoto University, Matsumoto, Japan.,Matsumoto University Graduate School of Health Science, Matsumoto, Japan
| | - Moe Ono
- Laboratory of Molecular Biology, Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi, Japan
| | - Takashi Tanaka
- Laboratory of Molecular Biology, Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi, Japan
| | - Koji Tomita
- Laboratory of Molecular Biology, Faculty of Pharmacy, Osaka Ohtani University, Tondabayashi, Japan
| | - Kazuya Yamada
- Department of Health and Nutritional Science, Faculty of Human Health Science, Matsumoto University, Matsumoto, Japan.,Matsumoto University Graduate School of Health Science, Matsumoto, Japan
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Giglio RV, Carruba G, Cicero AF, Banach M, Patti AM, Nikolic D, Cocciadiferro L, Zarcone M, Montalto G, Stoian AP, Banerjee Y, Rizvi AA, Toth PP, Rizzo M. Pasta Supplemented with Opuntia ficus-indica Extract Improves Metabolic Parameters and Reduces Atherogenic Small Dense Low-Density Lipoproteins in Patients with Risk Factors for the Metabolic Syndrome: A Four-Week Intervention Study. Metabolites 2020; 10:metabo10110428. [PMID: 33114614 PMCID: PMC7694062 DOI: 10.3390/metabo10110428] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/19/2020] [Accepted: 10/20/2020] [Indexed: 12/24/2022] Open
Abstract
Food supplementation with Opuntia ficus-indica (OFI) has been associated with a significant reduction in total cholesterol, body fat, hyperglycemia and blood pressure. Since OFI may also have antioxidant and anti-atherogenic properties, we hypothesized that its supplementation might reduce atherogenic lipoproteins, including small, dense low-density lipoproteins (sdLDL). Forty-nine patients (13 men and 36 women, mean age: 56 ± 5 years) with one or two criteria for the metabolic syndrome weekly consumed 500 g of pasta supplemented with 3% OFI extract (30% of insoluble polysaccharides with high antioxidant power) for 1 month. The full LDL subclass profile was assessed by gel electrophoresis (Lipoprint, Quantimetrix, Redondo Beach, CA, USA). After 1 month of pasta supplementation, waist circumference (p = 0.0297), plasma glucose (p < 0.0001), triglycerides (p = 0.0137), plasma creatinine (p = 0.0244), urea and aspartate transaminase (p < 0.0001 for each) significantly decreased. A percentage increase in larger, less atherogenic LDL-1 (p = 0.0002), with a concomitant reduction in smaller, denser LDL-2 (p < 0.0001) and LDL-3 (p = 0.0004), were found. LDL-4 and-5 decreased, although not significantly. This is the first intervention study suggesting that pasta enriched with an OFI extract may have beneficial effects on some metabolic parameters and the LDL particle sizes, reducing atherogenic sdLDL. Future studies will help to establish if these findings impact cardiovascular outcomes.
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Affiliation(s)
- Rosaria Vincenza Giglio
- Department of Health Promotion Sciences Maternal and Infantile Care, Internal Medicine and Medical Specialties (PROMISE), University of Palermo, 90127 Palermo, Italy; (R.V.G.); (A.M.P.); (G.M.); (M.R.)
| | - Giuseppe Carruba
- Division of Research and Internationalization, ARNAS-Civico Di Cristina e Benfratelli, 90127 Palermo, Italy; (G.C.); (L.C.); (M.Z.)
| | - Arrigo F.G. Cicero
- Medical and Surgical Sciences Department, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy;
| | - Maciej Banach
- Department of Hypertension, WAM University Hospital in Lodz, Medical University of Lodz, 90-419 Lodz, Poland;
- Polish Mother’s Memorial Hospital Research Institute (PMMHRI) in Lodz, 93-338 Lodz, Poland
| | - Angelo Maria Patti
- Department of Health Promotion Sciences Maternal and Infantile Care, Internal Medicine and Medical Specialties (PROMISE), University of Palermo, 90127 Palermo, Italy; (R.V.G.); (A.M.P.); (G.M.); (M.R.)
| | - Dragana Nikolic
- Department of Health Promotion Sciences Maternal and Infantile Care, Internal Medicine and Medical Specialties (PROMISE), University of Palermo, 90127 Palermo, Italy; (R.V.G.); (A.M.P.); (G.M.); (M.R.)
- Correspondence: ; Tel.: +39-091-655-4703
| | - Letizia Cocciadiferro
- Division of Research and Internationalization, ARNAS-Civico Di Cristina e Benfratelli, 90127 Palermo, Italy; (G.C.); (L.C.); (M.Z.)
| | - Maurizio Zarcone
- Division of Research and Internationalization, ARNAS-Civico Di Cristina e Benfratelli, 90127 Palermo, Italy; (G.C.); (L.C.); (M.Z.)
| | - Giuseppe Montalto
- Department of Health Promotion Sciences Maternal and Infantile Care, Internal Medicine and Medical Specialties (PROMISE), University of Palermo, 90127 Palermo, Italy; (R.V.G.); (A.M.P.); (G.M.); (M.R.)
| | - Anca Pantea Stoian
- Department of Diabetes, Nutrition and Metabolic Diseases, Carol Davila University of Medicine and Pharmacy, 050474 Bucharest, Romania;
| | - Yajnavalka Banerjee
- Department of Biochemistry, Mohammed Bin Rashid University of Medicine and Health Sciences, 505055 Dubai, UAE;
| | - Ali A. Rizvi
- Division of Endocrinology, Diabetes and Metabolism, University of South Carolina School of Medicine, Columbia, SC 29203, USA;
- Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Peter P. Toth
- CGH Medical Center, Sterling, IL 61081, USA;
- School of Medicine, University of Illinois, Peoria, IL 60612, USA
- School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Manfredi Rizzo
- Department of Health Promotion Sciences Maternal and Infantile Care, Internal Medicine and Medical Specialties (PROMISE), University of Palermo, 90127 Palermo, Italy; (R.V.G.); (A.M.P.); (G.M.); (M.R.)
- Division of Endocrinology, Diabetes and Metabolism, University of South Carolina School of Medicine, Columbia, SC 29203, USA;
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Toth PP, Patti AM, Nikolic D, Giglio RV, Castellino G, Biancucci T, Geraci F, David S, Montalto G, Rizvi A, Rizzo M. Bergamot Reduces Plasma Lipids, Atherogenic Small Dense LDL, and Subclinical Atherosclerosis in Subjects with Moderate Hypercholesterolemia: A 6 Months Prospective Study. Front Pharmacol 2016; 6:299. [PMID: 26779019 PMCID: PMC4702027 DOI: 10.3389/fphar.2015.00299] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 12/07/2015] [Indexed: 12/22/2022] Open
Abstract
Background: Some patients experience statin-induced side effects or prefer nutraceutical approaches for the treatment of dyslipidemia. This has led to a search for alternative therapeutic approaches for dyslipidemia management. In recent studies Citrus bergamia (known as Bergamot) juice was able to reduce serum levels of lipids. Such benefit may be attributed to high amounts of flavonoids contained in Bergamot fruit juice (neoeriocitrin, neohesperidin, naringin). The aim of the present study was to fully investigate the effects of a Bergamot extract on cardio-metabolic parameters, including plasma lipids, atherogenic lipoproteins and subclinical atherosclerosis. Methods: Eighty subjects (42 men and 38 women, mean age: 55 ± 13 years) with moderate hypercholesterolemia [e.g., with plasma LDL-cholesterol concentrations between 160 and 190 mg/dl (between 4.1 and 4.9 mmol/l)] were included. A Bergamot-derived extract (Bergavit R®) was given at a fixed dose daily (150 mg of flavonoids, with 16% of neoeriocitrin, 47% of neohesperidin and 37% of naringin) for 6 months. Lipoprotein subfractions were assessed by gel electrophoresis. With this methodology low density lipoprotein (LDL) subclasses are distributed as seven bands (LDL-1 and -2 as large LDL, and LDL-3 to -7 as atherogenic small, dense LDL). Subclinical atherosclerosis was assessed by carotid intima-media thickness (cIMT) using B-mode ultrasound. Results: After 6 months, Bergavit R® reduced total cholesterol (from 6.6 ± 0.4 to 5.8 ± 1.1 mmol/l, p < 0.0001), triglycerides (from 1.8 ± 0.6 to 1.5 ± 0.9 mmol/l, p = 0.0020), and LDL-cholesterol (from 4.6 ± 0.2 to 3.7 ± 1.0 mmol/l, p < 0.0001), while HDL- cholesterol increased (from 1.3 ± 0.2 to 1.4 ± 0.4 mmol/l, p < 0.0007). In addition, a significant increase in LDL-1 (from 41.2 ± 0.2 to 49.6 ± 0.2%, p < 0.0001) was accompanied by decreased small, dense LDL-3, -4, and 5 particles (from 14.5 ± 0.1 to 9.0 ± 0.1% p < 0.0001; 3.2 ± 0.1 to 1.5 ± 0.1% p = 0.0053; 0.3 ± 0.0% to 0.1 ± 0.0% p = 0.0133, respectively). cIMT also decreased from 1.2 ± 0.4 to 0.9 ± 0.1 mm (p < 0.0001). Conclusion: This is the first study investigating the effects of Bergamot flavonoids supplementation on cardio-metabolic risk in dyslipidemic subjects. Bergavit R® (Bergamot juice extract) supplementation significantly reduced plasma lipids and improved the lipoprotein profile. cIMT was also reduced significantly over a relatively short time frame of 6 months.
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Affiliation(s)
- Peter P Toth
- CGH Medical Center, SterlingIL, USA; School of Medicine, University of Illinois, PeoriaIL, USA; Johns Hopkins University School of Medicine, BaltimoreMD, USA
| | - Angelo M Patti
- Biomedical Department of Internal Medicine and Medical Specialties, University of PalermoPalermo, Italy; Euro-Mediterranean Institute of Science and TechnologyPalermo, Italy
| | - Dragana Nikolic
- Biomedical Department of Internal Medicine and Medical Specialties, University of Palermo Palermo, Italy
| | - Rosaria V Giglio
- Biomedical Department of Internal Medicine and Medical Specialties, University of PalermoPalermo, Italy; Euro-Mediterranean Institute of Science and TechnologyPalermo, Italy
| | - Giuseppa Castellino
- Biomedical Department of Internal Medicine and Medical Specialties, University of Palermo Palermo, Italy
| | - Teresa Biancucci
- Biomedical Department of Internal Medicine and Medical Specialties, University of Palermo Palermo, Italy
| | - Fabiana Geraci
- Euro-Mediterranean Institute of Science and TechnologyPalermo, Italy; Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of PalermoPalermo, Italy
| | - Sabrina David
- Department of Experimental Biomedicine and Clinical Neuroscience, University of Palermo Palermo, Italy
| | - Giuseppe Montalto
- School of Medicine, University of Illinois, PeoriaIL, USA; Consiglio Nazionale delle Ricerche, Istituto di Biomedicina e Immunologia Molecolare "Alberto Monroy"Palermo, Italy
| | - Ali Rizvi
- Division of Endocrinology, Diabetes and Metabolism, University of South Carolina School of Medicine, Columbia SC, USA
| | - Manfredi Rizzo
- Biomedical Department of Internal Medicine and Medical Specialties, University of PalermoPalermo, Italy; Euro-Mediterranean Institute of Science and TechnologyPalermo, Italy; Division of Endocrinology, Diabetes and Metabolism, University of South Carolina School of Medicine, ColumbiaSC, USA
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Bridging cell surface receptor with nuclear receptors in control of bile acid homeostasis. Acta Pharmacol Sin 2015; 36:113-8. [PMID: 25500873 DOI: 10.1038/aps.2014.118] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 09/10/2014] [Indexed: 12/12/2022] Open
Abstract
Bile acids (BAs) are traditionally considered as "physiological detergents" for emulsifying hydrophobic lipids and vitamins due to their amphipathic nature. But accumulating clinical and experimental evidence shows an association between disrupted BA homeostasis and various liver disease conditions including hepatitis infection, diabetes and cancer. Consequently, BA homeostasis regulation has become a field of heavy interest and investigation. After identification of the Farnesoid X Receptor (FXR) as an endogenous receptor for BAs, several nuclear receptors (SHP, HNF4α, and LRH-1) were also found to be important in regulation of BA homeostasis. Some post-translational modifications of these nuclear receptors have been demonstrated, but their physiological significance is still elusive. Gut secrets FGF15/19 that can activate hepatic FGFR4 and its downstream signaling cascade, leading to repressed hepatic BA biosynthesis. However, the link between the activated kinases and these nuclear receptors is not fully elucidated. Here, we review the recent literature on signal crosstalk in BA homeostasis.
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Tavares-Sanchez OL, Rodriguez C, Gortares-Moroyoqui P, Estrada MI. Hepatocyte nuclear factor-4α, a multifunctional nuclear receptor associated with cardiovascular disease and cholesterol catabolism. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2014; 25:126-139. [PMID: 24848804 DOI: 10.1080/09603123.2014.915015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Cardiovascular diseases (CVDs), the leading cause of death worldwide, are associated with high plasma cholesterol levels. The conversion of cholesterol to bile acids (BAs) accounts for about 50% of total cholesterol elimination from the body. This phenomenon occurs in the liver and is regulated by nuclear receptors such as hepatocyte nuclear factor-4α (HNF-4α). Therefore, special emphasis is given to HNF-4α properties and its multifunctional role, particularly in the conversion of cholesterol to BAs. HNF-4α is a highly conserved transcription factor that has the potential capacity to transactivate a vast number of genes, including CYP7 which codes for cholesterol 7α-hydroxylase (CYP7A1; EC 1.14.13.17), the rate-limiting enzyme of BA biosynthesis. The fact that HNF-4α transactivation potential can be modulated via phosporylation is of particular interest. Additional findings on structural and functional characteristics of HNF-4α may eventually present alternatives to control the levels of cholesterol in the body and consequently reduce the risk of CVDs.
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Affiliation(s)
- Olga Lidia Tavares-Sanchez
- a Departamento de Biotecnología y Ciencias Alimentarias , Instituto Tecnológico de Sonora , Ciudad Obregón , Mexico
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Chandra V, Holla P, Ghosh D, Chakrabarti D, Padigaru M, Jameel S. The hepatitis E virus ORF3 protein regulates the expression of liver-specific genes by modulating localization of hepatocyte nuclear factor 4. PLoS One 2011; 6:e22412. [PMID: 21799848 PMCID: PMC3140526 DOI: 10.1371/journal.pone.0022412] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 06/21/2011] [Indexed: 12/17/2022] Open
Abstract
The hepatitis E virus (HEV) is a small RNA virus and the cause of acute viral hepatitis E. The open reading frame 3 protein (pORF3) of HEV appears to be a pleiotropic regulatory protein that helps in the establishment, propagation and progression of viral infection. However, the global cellular effects of this protein remain to be explored. In the absence of traditional in vitro viral infection systems or efficient replicon systems, we made an adenovirus based ORF3 protein expression system to study its effects on host cell gene expression. We infected Huh7 hepatoma cells with recombinant adenoviruses expressing pORF3 and performed microarray-based gene expression analyses. Several genes down regulated in pORF3-expressing cells were found to be under regulation of the liver-enriched hepatocyte nuclear factor 4 (HNF4), which regulates hepatocyte-specific gene expression. While HNF4 localizes to the nucleus, its phosphorylation results in impaired nuclear localization of HNF4. Here we report that pORF3 increases HNF4 phosphorylation through the ERK and Akt kinases, which results in impaired nuclear translocation of HNF4 and subsequently the down modulation of HNF4-responsive genes in pORF3-expressing cells. We propose that modulation of several hepatocyte specific genes by pORF3 will create an environment favorable for viral replication and pathogenesis.
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Affiliation(s)
- Vivek Chandra
- Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - Prasida Holla
- Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - Dhrubaa Ghosh
- Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | | | | | - Shahid Jameel
- Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
- * E-mail:
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11
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Váradi A, Szabó Z, Pomozi V, de Boussac H, Fülöp K, Arányi T. ABCC6 as a target in pseudoxanthoma elasticum. Curr Drug Targets 2011; 12:671-82. [PMID: 21039331 PMCID: PMC3324121 DOI: 10.2174/138945011795378612] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2009] [Accepted: 05/10/2010] [Indexed: 01/30/2023]
Abstract
The ABCC6 gene encodes an organic anion transporter protein, ABCC6/MRP6. Mutations in the gene cause a rare, recessive genetic disease, pseudoxanthoma elasticum, while the loss of one ABCC6 allele is a genetic risk factor in coronary artery disease. We review here the information available on gene structure, evolution as well as the present knowledge on its transcriptional regulation. We give a detailed description of the characteristics of the protein, and analyze the relationship between the distributions of missense disease-causing mutations in the predicted three-dimensional structure of the transporter, which suggests functional importance of the domain-domain interactions. Though neither the physiological function of the protein nor its role in the pathobiology of the diseases are known, a current hypothesis that ABCC6 may be involved in the efflux of one form of Vitamin K from the liver is discussed. Finally, we analyze potential strategies how the gene can be targeted on the transcriptional level to increase protein expression in order to compensate for reduced activity. In addition, pharmacologic correction of trafficking-defect mutants or suppression of stop codon mutations as potential future therapeutic interventions are also reviewed.
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Affiliation(s)
- András Váradi
- Institute of Enzymology, Hungarian Academy of Sciences, Budapest, Hungary.
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12
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Expression profile analysis of the inflammatory response regulated by hepatocyte nuclear factor 4α. BMC Genomics 2011; 12:128. [PMID: 21352552 PMCID: PMC3053261 DOI: 10.1186/1471-2164-12-128] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 02/25/2011] [Indexed: 12/17/2022] Open
Abstract
Background Hepatocyte nuclear factor 4α (HNF4α), a liver-specific transcription factor, plays a significant role in liver-specific functions. However, its functions are poorly understood in the regulation of the inflammatory response. In order to obtain a genomic view of HNF4α in this context, microarray analysis was used to probe the expression profile of an inflammatory response induced by cytokine stimulation in a model of HNF4α knock-down in HepG2 cells. Results The expression of over five thousand genes in HepG2 cells is significantly changed with the dramatic reduction of HNF4α concentration compared to the cells with native levels of HNF4α. Over two thirds (71%) of genes that exhibit differential expression in response to cytokine treatment also reveal differential expression in response to HNF4α knock-down. In addition, we found that a number of HNF4α target genes may be indirectly mediated by an ETS-domain transcription factor ELK1, a nuclear target of mitogen-activated protein kinase (MAPK). Conclusion The results indicate that HNF4α has an extensive impact on the regulation of a large number of the liver-specific genes. HNF4α may play a role in regulating the cytokine-induced inflammatory response. This study presents a novel function for HNF4α, acting not only as a global player in many cellular processes, but also as one of the components of inflammatory response in the liver.
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Chiang JYL. Hepatocyte nuclear factor 4alpha regulation of bile acid and drug metabolism. Expert Opin Drug Metab Toxicol 2010; 5:137-47. [PMID: 19239393 DOI: 10.1517/17425250802707342] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The hepatocyte nuclear factor 4alpha (HNF4alpha) is a liver-enriched nuclear receptor that plays a critical role in early morphogenesis, fetal liver development, liver differentiation and metabolism. Human HNF4alpha gene mutations cause maturity on-set diabetes of the young type 1, an autosomal dominant non-insulin-dependent diabetes mellitus. HNF4alpha is an orphan nuclear receptor because of which the endogenous ligand has not been firmly identified. The trans-activating activity of HNF4alpha is enhanced by interacting with co-activators and inhibited by corepressors. Recent studies have revealed that HNF4alpha plays a central role in regulation of bile acid metabolism in the liver. Bile acids are required for biliary excretion of cholesterol and metabolites, and intestinal absorption of fat, nutrients, drug and xenobiotics for transport and distribution to liver and other tissues. Bile acids are signaling molecules that activate nuclear receptors to control lipids and drug metabolism in the liver and intestine. Therefore, HNF4alpha plays a central role in coordinated regulation of bile acid and xenobiotics metabolism. Drugs that specifically activate HNF4alpha could be developed for treating metabolic diseases such as diabetes, dyslipidemia and cholestasis, as well as drug metabolism and detoxification.
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Affiliation(s)
- John Y L Chiang
- Northeastern Ohio Universities Colleges of Medicine and Pharmacy, Department of Integrative Medical Sciences, Rootstown, Ohio 44272, USA.
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de Boussac H, Ratajewski M, Sachrajda I, Köblös G, Tordai A, Pulaski L, Buday L, Váradi A, Arányi T. The ERK1/2-hepatocyte nuclear factor 4alpha axis regulates human ABCC6 gene expression in hepatocytes. J Biol Chem 2010; 285:22800-8. [PMID: 20463007 DOI: 10.1074/jbc.m110.105593] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
ABCC6 mutations are responsible for the development of pseudoxanthoma elasticum, a rare recessive disease characterized by calcification of elastic fibers. Although ABCC6 is mainly expressed in the liver the disease has dermatologic, ocular, and cardiovascular symptoms. We investigated the transcriptional regulation of the gene and observed that hepatocyte growth factor (HGF) inhibits its expression in HepG2 cells via the activation of ERK1/2. Similarly, other factors activating the cascade also inhibited ABCC6 expression. We identified the ERK1/2 response element in the proximal promoter by luciferase reporter gene assays. This site overlapped with a region conferring the tissue-specific expression pattern to the gene and with a putative hepatocyte nuclear factor 4alpha (HNF4alpha) binding site. We demonstrated that HNF4alpha regulates the expression of ABCC6, acts through the putative binding site, and determines its cell type-specific expression. We also showed that HNF4alpha is inhibited by the activation of the ERK1/2 cascade. In conclusion we describe here the first regulatory pathway of ABCC6 expression showing that the ERK1/2-HNF4alpha axis has an important role in regulation of the gene.
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Affiliation(s)
- Hugues de Boussac
- Institute of Enzymology, Hungarian Academy of Sciences, Karolina ut 29, 1113 Budapest, Hungary
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15
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Mogilenko DA, Dizhe EB, Shavva VS, Lapikov IA, Orlov SV, Perevozchikov AP. Role of the nuclear receptors HNF4 alpha, PPAR alpha, and LXRs in the TNF alpha-mediated inhibition of human apolipoprotein A-I gene expression in HepG2 cells. Biochemistry 2010; 48:11950-60. [PMID: 19883121 DOI: 10.1021/bi9015742] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The expression of the apolipoprotein A-I gene (apoA-I) in hepatocytes is repressed by pro-inflammatory cytokines such as IL-1beta and TNFalpha. In this work, we have demonstrated that treatment of HepG2 human hepatoma cells with chemical inhibitors for JNK, p38 protein kinases, and NFkappaB transcription factor abolishes the TNFalpha-mediated inhibition of human apoA-I gene expression in HepG2 cells. In addition, we have shown that TNFalpha decreases also the rate of secretion of apoA-I protein by HepG2 cells, and this effect depends on JNK and p38, but not on NFkappaB and MEK1/2 signaling pathways. The inhibitory effect of TNFalpha has been found to be mediated by the hepatic enhancer of the apoA-I gene. The decrease in the level of human apoA-I gene expression under the impact of TNFalpha appears to be partly mediated by the inhibition of HNF4alpha and PPARalpha gene expression. Treatment of HepG2 cells with PPARalpha antagonist (MK886) or LXR agonist (TO901317) abolishes the TNFalpha-mediated decrease in the level of apoA-I gene expression. PPARalpha agonist (WY-14643) abolishes the negative effect of TNFalpha on apoA-I gene expression in the case of simultaneous inhibition of MEK1/2, although neither inhibition of MEK1/2 nor addition of WY-14643 leads to the blocking of the TNFalpha-mediated decrease in the level of apoA-I gene expression individually. The ligand-dependent regulation of apoA-I gene expression by PPARalpha appears to be affected by the TNFalpha-mediated activation of MEK1/2 kinases, probably through PPARalpha phosphorylation. Treatment of HepG2 cells with PPARalpha and LXR synthetic agonists also blocks the inhibition of apoA-I protein secretion in HepG2 cells under the impact of TNFalpha. A chromatin immunoprecipitation assay demonstrates that TNFalpha leads to a 2-fold decrease in the level of PPARalpha binding with the apoA-I gene hepatic enhancer. At the same time, the level of LXRbeta binding with the apoA-I gene hepatic enhancer is increased 3-fold under the impact of TNFalpha. These results suggest that nuclear receptors HNF4alpha, PPARalpha, and LXRs are involved in the TNFalpha-mediated downregulation of human apoA-I gene expression and apoA-I protein secretion in HepG2 cells.
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Affiliation(s)
- Denis A Mogilenko
- Department of Biochemistry, Institute of Experimental Medicine, Russian Academy of Medical Sciences, 197376 St. Petersburg, Russia.
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Boyd M, Bressendorff S, Møller J, Olsen J, Troelsen JT. Mapping of HNF4alpha target genes in intestinal epithelial cells. BMC Gastroenterol 2009; 9:68. [PMID: 19761587 PMCID: PMC2761415 DOI: 10.1186/1471-230x-9-68] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Accepted: 09/17/2009] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The role of HNF4alpha has been extensively studied in hepatocytes and pancreatic beta-cells, and HNF4alpha is also regarded as a key regulator of intestinal epithelial cell differentiation. The aim of the present work is to identify novel HNF4alpha target genes in the human intestinal epithelial cells in order to elucidate the role of HNF4alpha in the intestinal differentiation progress. METHODS We have performed a ChIP-chip analysis of the human intestinal cell line Caco-2 in order to make a genome-wide identification of HNF4alpha binding to promoter regions. The HNF4alpha ChIP-chip data was matched with gene expression and histone H3 acetylation status of the promoters in order to identify HNF4alpha binding to actively transcribed genes with an open chromatin structure. RESULTS 1,541 genes were identified as potential HNF4alpha targets, many of which have not previously been described as being regulated by HNF4alpha. The 1,541 genes contributed significantly to gene ontology (GO) pathways categorized by lipid and amino acid transport and metabolism. An analysis of the homeodomain transcription factor Cdx-2 (CDX2), the disaccharidase trehalase (TREH), and the tight junction protein cingulin (CGN) promoters verified that these genes are bound by HNF4alpha in Caco2 cells. For the Cdx-2 and trehalase promoters the HNF4alpha binding was verified in mouse small intestine epithelium. CONCLUSION The HNF4alpha regulation of the Cdx-2 promoter unravels a transcription factor network also including HNF1alpha, all of which are transcription factors involved in intestinal development and gene expression.
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Affiliation(s)
- Mette Boyd
- Department of Cellular and Molecular Medicine, Panum Institute, Building 6,4, University of Copenhagen, Blegdamsvej 3B 2200 Copenhagen N, Denmark.
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17
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Gonzalez FJ. Regulation of hepatocyte nuclear factor 4 alpha-mediated transcription. Drug Metab Pharmacokinet 2008; 23:2-7. [PMID: 18305369 DOI: 10.2133/dmpk.23.2] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Hepatocyte nuclear factor 4alpha (HNF4alpha, NR2A1) is required for development of the liver and for controlling the expression of many genes specifically expressed in the liver and associated with a number of critical metabolic pathways. Among the genes regulated by HNF4alpha are the xenobiotic-metabolizing cytochromes P450, UDP-glucuronosyltransferases and sulfotransferases thus making this transcription factor critical in the control of drug metabolism. HNF4alpha, a member of the nuclear receptor superfamily, binds as a homodimer to direct repeat elements upstream of target genes. However, in contrast to many other nuclear receptors, there is no convincing evidence that HNF4alpha is activated by exogenous ligands, at least in the classic mechanism used by other steroid and metabolic nuclear receptors. X-ray crystallographic studies revealed that HNF4alpha has a fatty acid embedded in its putative ligand binding site that may not be easily released or displaced by exogenous ligands. HNF4alpha, as a general rule, controls constitutive expression of many hepatic genes but under certain circumstances can be subjected to regulation by differential co-activator recruitment, by phosphorylation and by interaction with other nuclear receptors. The ability of HNF4alpha to be regulated offers hope that it could be a drug target.
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Affiliation(s)
- Frank J Gonzalez
- Laboratory of Metabolism, National Cancer Institute, National Instituted of Health, Bethesda, Maryland 20892, USA.
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18
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Shin M, Kim I, Inoue Y, Kimura S, Gonzalez FJ. Regulation of mouse hepatic alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase, a key enzyme in the tryptophan-nicotinamide adenine dinucleotide pathway, by hepatocyte nuclear factor 4alpha and peroxisome proliferator-activated receptor alpha. Mol Pharmacol 2006; 70:1281-90. [PMID: 16807375 DOI: 10.1124/mol.106.026294] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nicotinamide adenine dinucleotide (NAD) plays a critical role in the maintenance of cellular energy homeostasis. alpha-Amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) is the key enzyme regulating de novo synthesis of NAD from l-tryptophan (Trp), designated the Trp-NAD pathway. Acmsd gene expression was found to be under the control of both hepatocyte nuclear factor 4alpha (HNF4alpha) and peroxisome proliferator-activated receptor alpha (PPARalpha). Constitutive expression of ACMSD mRNA levels were governed by HNF4alpha and downregulated by activation of PPARalpha by the ligand Wy-14,643 ([4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid]), as revealed by studies with hepatic HNF4alpha-null mice and PPARalpha-null mice, respectively. Transient transfection and electrophoretic mobility shift analyses showed an HNF4alpha binding site in the Acmsd gene promoter that directed transactivation of reporter gene constructs by HNF4alpha. The Acmsd promoter was not responsive to PPARalpha in transactivation assays. Wy-14,643 treatment decreased HNF4alpha protein levels in wild-type, but not PPARalpha-null, mouse livers, with no changes in HNF4alpha mRNA. These results show that Wy-14,643, through PPARalpha, post-transcriptionally down-regulates HNF4alpha protein levels, leading to reduced expression of the HNF4alpha target gene Acmsd.
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Affiliation(s)
- Mariko Shin
- Laboratory of Metabolism, Building 37, Room 3106, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Li T, Jahan A, Chiang JYL. Bile acids and cytokines inhibit the human cholesterol 7 alpha-hydroxylase gene via the JNK/c-jun pathway in human liver cells. Hepatology 2006; 43:1202-10. [PMID: 16729332 PMCID: PMC1526464 DOI: 10.1002/hep.21183] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cholesterol 7 alpha-hydroxylase (CYP7A1) of the bile acid biosynthesis pathway is suppressed by bile acids and inflammatory cytokines. Bile acids are known to induce inflammatory cytokines to activate the mitogen-activated protein kinase/c-Jun N-terminal kinase (JNK) signaling pathway that inhibits CYP7A1 gene transcription. c-Jun has been postulated to mediate bile acid inhibition of CYP7A1. However, the c-Jun target involved in the regulation of CYP7A1 is unknown. Human primary hepatocytes and HepG2 cells were used as models to study chenodeoxycholic acid (CDCA) and interleukin-1 beta (IL-1 beta) regulation of human CYP7A1 gene expression via real-time polymerase chain reaction, reporter assays, co-immunoprecipitation and chromatin immunocipitation (ChIP) assays. IL-1 beta and CDCA reduced CYP7A1 but induced c-Jun messenger RNA expression in human primary hepatocytes. IL-1beta inhibited human CYP7A1 reporter activity via the HNF4 alpha binding site. A JNK-specific inhibitor blocked the inhibitory effect of IL-1 beta on HNF4 alpha expression and CYP7A1 reporter activity. c-Jun inhibited HNF4 alpha and PPARgamma coactivator-1 alpha (PGC-1 alpha) coactivation of CYP7A1 reporter activity, whereas a dominant negative c-Jun did not. Co-immunoprecipitation and ChIP assays revealed that IL-1 beta and CDCA reduced HNF4 alpha bound to the CYP7A1 chromatin, and that c-Jun interacted with HNF4 alpha and blocked HNF4 alpha recruitment of PGC-1 alpha to the CYP7A1 chromatin. In conclusion, IL-1 beta and CDCA inhibit HNF4 alpha but induce c-Jun, which in turn blocks HNF 4 alpha recruitment of PGC-1 alpha to the CYP7A1 chromatin and results in inhibition of CYP7A1 gene transcription. The JNK/c-Jun signaling pathway inhibits bile acid synthesis and protects hepatocytes against the toxic effect of inflammatory agents.
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Affiliation(s)
- Tiangang Li
- Department of Microbiology, Immunology, and Biochemistry, Northeastern Ohio Universities College of Medicine, Rootstown, OH 44272, USA
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Furihata T, Hosokawa M, Masuda M, Satoh T, Chiba K. Hepatocyte nuclear factor-4alpha plays pivotal roles in the regulation of mouse carboxylesterase 2 gene transcription in mouse liver. Arch Biochem Biophys 2006; 447:107-17. [PMID: 16527247 DOI: 10.1016/j.abb.2006.01.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2005] [Revised: 01/25/2006] [Accepted: 01/25/2006] [Indexed: 10/25/2022]
Abstract
The mouse carboxylesterase 2 isozyme, mCES2, is thought to play important roles in lipid metabolism and is expressed in the liver, kidney, and small intestine at high levels. In this study, we examined the molecular mechanisms controlling this tissue-specific expression of mCES2, and demonstrated that hepatocyte nuclear factor-4alpha (HNF-4alpha) could enhance transcription of the mCES2 gene in vitro and in vivo. It was found that effects of HNF-4alpha on the level of mCES2 promoter activity were repressed by small heterodimer partner (SHP) and chenodeoxycholic acid (CDCA) in luciferase assays. Accordingly, mCES2 gene transcription was repressed by CDCA treatment in mouse immortalized hepatocytes. Our results suggested that this repression resulted from the combined effects of both inhibition of HNF-4alpha transactivation ability by SHP and reduction of HNF-4alpha expression level. These findings show that HNF-4alpha plays an important role in the regulation of mCES2 gene transcription.
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Affiliation(s)
- Tomomi Furihata
- Laboratory of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 260-8675, Japan
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21
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Prieur X, Schaap FG, Coste H, Rodríguez JC. Hepatocyte Nuclear Factor-4α Regulates the Human Apolipoprotein AV Gene: Identification of a Novel Response Element and Involvement in the Control by Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α, AMP-Activated Protein Kinase, and Mitogen-Activated Protein Kinase Pathway. Mol Endocrinol 2005; 19:3107-25. [PMID: 16051671 DOI: 10.1210/me.2005-0048] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The recently discovered apolipoprotein AV (apoAV) gene has been reported to be a key player in modulating plasma triglyceride levels. Here we identify the hepatocyte nuclear factor-4alpha (HNF-4alpha) as a novel regulator of human apoAV gene. Inhibition of HNF-4alpha expression by small interfering RNA resulted in down-regulation of apoAV. Deletion, mutagenesis, and binding assays revealed that HNF-4alpha directly regulates human apoAV promoter through DR1 [a direct repeat separated by one nucleotide (nt)], and via a novel element for HNF-4alpha consisting of an inverted repeat separated by 8 nt (IR8). In addition, we show that the coactivator peroxisome proliferator-activated receptor-gamma coactivator-1alpha was capable of stimulating the HNF-4alpha-dependent transactivation of apoAV promoter. Furthermore, analyses in human hepatic cells demonstrated that AMP-activated protein kinase (AMPK) and the MAPK signaling pathway regulate human apoAV expression and suggested that this regulation may be mediated, at least in part, by changes in HNF-4alpha. Intriguingly, EMSAs and mice with a liver-specific disruption of the HNF-4alpha gene revealed a species-distinct regulation of apoAV by HNF-4alpha, which resembles that of a subset of HNF-4alpha target genes. Taken together, our data provide new insights into the binding properties and the modulation of HNF-4alpha and underscore the role of HNF-4alpha in regulating triglyceride metabolism.
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Affiliation(s)
- Xavier Prieur
- GlaxoSmithKline, 25 avenue du Québec, 91951 Les Ulis cedex, France
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Jahan A, Chiang JYL. Cytokine regulation of human sterol 12alpha-hydroxylase (CYP8B1) gene. Am J Physiol Gastrointest Liver Physiol 2005; 288:G685-95. [PMID: 15550563 DOI: 10.1152/ajpgi.00207.2004] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Sterol 12alpha-hydroxylase (CYP8B1) catalyzes cholic acid synthesis in the liver and is feedback inhibited by bile acids. In addition to activating farnesoid X receptor (nuclear receptor subfamily 1H4), bile acids also induce inflammatory cytokines in hepatocytes. The objective of this study was to investigate the mechanism by which inflammatory cytokines inhibit human CYP8B1 gene transcription. Real-time PCR assays revealed that both chenodeoxycholic acid (CDCA) and interleukin-1beta (IL-1beta) markedly reduced CYP8B1, cholesterol 7alpha-hydroxylase CYP7A1 and hepatic nuclear factor 4alpha (HNF4alpha) mRNA expression levels in human primary hepatocytes. However, CDCA induced, but IL-1beta reduced, small heterodimer partner (SHP) mRNA expression. IL-1beta inhibited human CYP8B1 reporter activity only in liver cells, and a c-Jun NH(2)-terminal kinase (JNK)-specific inhibitor-blocked IL-1beta inhibition. Activated JNK1 or c-Jun inhibited, whereas their dominant negative forms blocked, IL-1beta inhibition of CYP8B1 transcription. Mutagenesis analyses mapped an IL-1beta response element to a previously identified bile acid response element, which contains an HNF4alpha binding site. A dominant negative HNF4alpha inhibited CYP8B1 gene transcription and ectopically expressed HNF4alpha blocked IL-1beta inhibition. Furthermore, IL-1beta inhibited HNF4alpha gene transcription, protein expression, and binding to the CYP8B1 gene. JNK1 phosphorylated HNF4alpha and a JNK-specific inhibitor blocked the IL-1beta inhibition of HNF4alpha expression. These results suggest that IL-1beta inhibits CYP8B1 gene transcription via a mitogen-activated protein kinase/JNK pathway that inhibits HNF4alpha gene expression and its DNA-binding ability. This mechanism may play an important role in the adaptive response to inflammatory cytokines and in the protection of the liver during cholestasis.
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Affiliation(s)
- Asmeen Jahan
- Dept. of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, 4209 State Route 44, P. O Box 95, Rootstown, OH 44272, USA
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Nitanai A, Katoh N, Oikawa S, Saitoh M, Hamada M, Kutsuzawa A, Mohamed T, Uchida E, Endoh D, Kurosawa T, Sato H. Decreases in serum apolipoprotein C-III concentration in cows with ethionine-induced fatty liver. J Vet Med Sci 2005; 66:1113-8. [PMID: 15472476 DOI: 10.1292/jvms.66.1113] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To monitor the serum concentration of apolipoprotein C-III (apoC-III), one of the functional apoproteins in lipid metabolism, in cows with ethionine-induced fatty liver, and to investigate the association of apoC-III with liver triglyceride (TG) content and serum biochemical variables, seven nonpregnant nonlactating Holstein cows (3 to 6 years old) were used. Five cows were treated with ethionine, an analogue of methionine, (days 0, 7 and 14). The remaining two controls received saline as the vehicle. Liver TG contents in the treated cows were increased markedly whenever administered, and significant increases were observed at days 14 (666.4%, 85.3 mg/g) and 21 (675.0%, 86.4 mg/g) compared with day 0. In controls, no significant changes in liver TG content and serum biochemical variables were observed during this experiment. The serum apoC-III concentration in the treated cows was decreased drastically after the first administration and fell to the lowest value at day 10 (76.2 microg/ml, 32% of day 0). The apoC-III was significantly (p<0.05) correlated with non-esterified fatty acids (r= -0.526), gamma-glutamyl transpeptidase (r= -0.407), total bilirubin (r= -0.464), positively with apolipoprotein B-100 (apoB-100, r=0.601) and cholesterol ester (r=0.449). Although apoB-100 concentrations were also reduced by the administrations, the concentrations tended to recover smoothly toward the next administration. The distinct difference in change between apoC-III and apoB-100 suggests that apoC-III may be regulated by other pathways, in addition to inhibiting the synthesis of apoproteins by ethionine.
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Affiliation(s)
- Atsushi Nitanai
- Department of Veterinary Internal Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan
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Hirokane H, Nakahara M, Tachibana S, Shimizu M, Sato R. Bile acid reduces the secretion of very low density lipoprotein by repressing microsomal triglyceride transfer protein gene expression mediated by hepatocyte nuclear factor-4. J Biol Chem 2004; 279:45685-92. [PMID: 15337761 DOI: 10.1074/jbc.m404255200] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Microsomal triglyceride transfer protein (MTP) is involved in the transfer of triglycerides, cholesterol esters, and phospholipids to newly synthesized apolipoprotein (apo) B. It is therefore essential for lipoprotein synthesis and secretion in the liver and the small intestine. Although several recent experiments have revealed the transcriptional regulation of the MTP gene, little has been revealed to date about hepatocyte nuclear factor-4 (HNF-4)-dependent regulation. We here report that the human MTP gene promoter contains a pair of functional responsive elements for HNF-4 and HNF-1, the latter of which is another target gene of HNF-4. Chromatin immunoprecipitation assays provide evidence that endogenous HNF-4 and HNF-1 can bind these elements in chromatin. In Hep G2 cells overexpression of either a dominant negative form of HNF-4 or small interfering RNAs (siRNAs) against HNF-4 dramatically reduces the activities of both the wild type and the HNF-4 site mutant MTP promoter. This suggests that HNF-4 regulates MTP gene expression either directly or indirectly through elevated HNF-1 levels. When Hep G2 cells were cultured with chenodeoxycholic acid (CDCA), a ligand for the farnesoid X receptor (FXR), mRNA levels for MTP and apo B were reduced because of increased expression of the factor small heterodimer partner (SHP), which factor suppresses HNF-4 activities. Chenodeoxycholic acid, but not a synthetic FXR ligand, attenuated expression of HNF-4, bringing about a further suppression of MTP gene expression. Over time the intracellular MTP protein levels and apo B secretion in the culture medium significantly declined. These results indicate that two nuclear receptors, HNF-4 and FXR, are closely involved in MTP gene expression, and the results provide evidence for a novel interaction between bile acids and lipoprotein metabolism.
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Affiliation(s)
- Hisako Hirokane
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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25
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Wiwi CA, Gupte M, Waxman DJ. Sexually dimorphic P450 gene expression in liver-specific hepatocyte nuclear factor 4alpha-deficient mice. Mol Endocrinol 2004; 18:1975-87. [PMID: 15155787 DOI: 10.1210/me.2004-0129] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Hepatocyte nuclear factor (HNF) 4alpha is a liver-enriched nuclear receptor that plays a critical role in regulating the expression of numerous hepatic genes, including members of the cytochrome P450 (CYP) superfamily, several of which are expressed in a sex-dependent manner. Presently, we use a liver-specific Hnf4alpha-deficient mouse model to investigate the role of HNF4alpha in regulating liver-enriched transcription factors and sexually dimorphic Cyps in liver in vivo. Real-time PCR analysis of RNA isolated from livers of wild-type and Hnf4alpha-deficient mice revealed the following: 1) HNF4alpha exerts both positive regulation (Hnfalpha, C/ebpalpha, and C/ebpbeta) and negative regulation (Hnf3alpha and the HNF4alpha coactivator Pgc-1alpha) on liver transcription factor expression; 2) a strong dependence on HNF4alpha characterizes several male-predominant Cyps (2d9 and 8b1), female-predominant Cyps (2b10, 2b13, 3a41, and 3a44) and Cyps, whose expression is sex independent (3a11, 3a25); 3) HNF4alpha confers a unique, positive regulation of two male-expressed genes (Cyp4a12 and GSTpi) and a negative regulation of several female-predominant genes (Cyp2a4, Cyp2b9, Hnf3beta, and Hnf6), both of which are manifest in male but not female mouse liver. These trends were confirmed at the protein level by Western blot analysis using antibodies raised to Cyp2a, Cyp2b, and Cyp3a family members. Thus, HNF4alpha is an essential player in the complex regulatory network of liver-enriched transcription factors and the sexually dimorphic mouse Cyp genes that they regulate. HNF4alpha is proposed to contribute to the sex specificity of liver gene expression by positively regulating a subset of male-specific Cyp genes while concomitantly inhibiting the expression of certain female-specific Cyps and liver transcription factors, by mechanisms that are operative in male, but not female, mouse liver.
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Affiliation(s)
- Christopher A Wiwi
- Department of Biology, Boston University, 5 Cummington Street, Boston, Massachusetts 02215, USA
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26
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Hong YH, Varanasi US, Yang W, Leff T. AMP-activated protein kinase regulates HNF4alpha transcriptional activity by inhibiting dimer formation and decreasing protein stability. J Biol Chem 2003; 278:27495-501. [PMID: 12740371 DOI: 10.1074/jbc.m304112200] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
AMP-activated protein kinase (AMPK) is the central component of a cellular signaling system that regulates multiple metabolic enzymes and pathways in response to reduced intracellular energy levels. The transcription factor hepatic nuclear factor 4alpha (HNF4alpha) is an orphan nuclear receptor that regulates the expression of genes involved in energy metabolism in the liver, intestine, and endocrine pancreas. Inheritance of a single null allele of HNF4alpha causes diabetes in humans. Here we demonstrate that AMPK directly phosphorylates HNF4alpha and represses its transcriptional activity. AMPK-mediated phosphorylation of HNF4alpha on serine 304 had a 2-fold effect, reducing the ability of the transcription factor to form homodimers and bind DNA and increasing its degradation rate in vivo. These results demonstrate that HNF4alpha is a downstream target of AMPK and raise the possibility that one of the effects of AMPK activation is reduced expression of HNF4alpha target genes.
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Affiliation(s)
- Yu Holly Hong
- Department of Pathology and the Center for Integrative Metabolic and Endocrine Research, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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27
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Ning Q, Lakatoo S, Liu M, Yang W, Wang Z, Phillips MJ, Levy GA. Induction of prothrombinase fgl2 by the nucleocapsid protein of virulent mouse hepatitis virus is dependent on host hepatic nuclear factor-4 alpha. J Biol Chem 2003; 278:15541-9. [PMID: 12594208 DOI: 10.1074/jbc.m212806200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Fibrinogen-like protein 2/fibroleukin (Fgl2) plays a pivotal role in the pathogenesis of both experimental and human fulminant hepatic failure. We have reported recently that the nucleocapsid (N) protein from strains of murine hepatitis virus (MHV-3, MHV-A59), which cause massive hepatocellular necrosis but not from strains (MHV-JHM, MHV-2) which do not produce serious liver disease, induces transcription of fgl2. The purpose of the present study was to characterize both viral and host factor(s) necessary for viral induced transcription of fgl2. Mutation of residues Gly-12, Pro-38, Asn-40, Gln-41, and Asn-42 within domain 1 of the N protein of MHV-A59 to their corresponding residues found in MHV-2 abrogated fgl2 transcription, whereas mutation of other N protein domains, including a protein expressed from an internal reading frame (I protein), did not affect fgl2 gene transcription. We then examined the -372 to -306 sequence within the 1.3-kb fgl2 promoter region upstream from the transcription start site that was previously identified as necessary for N protein-induced gene transcription. We demonstrated that the -331/-325 HNF4 cis-element and its cognate transcription factor, HNF4alpha, are necessary for virus-induced fgl2 gene transcription. In uninfected macrophages and macrophages infected with MHV-2, an unidentified protein occupies the HNF4 cis-element. Following stimulation with MHV-A59, it was shown by electrophoretic mobility shift assay that HNF4alpha binds the HNF4 cis-element in the fgl2 promoter. We further report the unprecedented presence of HNF4alpha in peritoneal macrophages. Collectively, the results of this study define both viral and host factors necessary for induction of fgl2 prothrombinase gene transcription in MHV infection and may provide an explanation for the hepatotrophic nature of MHV-induced fulminant hepatic failure.
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Affiliation(s)
- Qin Ning
- Department of Infectious Disease, Institute of Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
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Bakovic M, Waite K, Vance DE. Oncogenic Ha-Ras transformation modulates the transcription of the CTP:phosphocholine cytidylyltransferase alpha gene via p42/44MAPK and transcription factor Sp3. J Biol Chem 2003; 278:14753-61. [PMID: 12584202 DOI: 10.1074/jbc.m300162200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We have shown previously that expression of the murine CTP:phosphocholine cytidylyltransferase (CT) alpha gene is regulated during cell proliferation (Golfman, L. S., Bakovic, M., and Vance, D. E. (2001) J. Biol. Chem. 276, 43688-43692). We have now characterized the role of Ha-Ras in the transcriptional regulation of the CTalpha gene. The expression of CTalpha and CTbeta2 proteins and mRNAs was stimulated in C3H10T1/2 murine fibroblasts expressing oncogenic Ha-Ras. Incubation of cells with the specific inhibitor (PD98059) of p42/44(MAPK) decreased the expression of both CT isoforms. Transfection of fibroblasts with CTalpha promoter-luciferase constructs resulted in an approximately 2-fold enhanced luciferase expression in Ha-Ras-transformed, compared with nontransformed, fibroblasts. Electromobility shift assays indicated enhanced binding of the Sp3 transcription factor to the CTalpha promoter in Ha-Ras-transformed cells. Expression of several forms of Sp3 was increased in nuclear extracts of Ha-Ras-transformed fibroblasts compared with nontransformed cells. Tyrosine phosphorylation of one Sp3 form was decreased, whereas phosphorylation of two other forms of Sp3 was increased in nuclear extracts of Ha-Ras-transformed cells. When control fibroblasts were transfected with a Sp3-expressing plasmid, an enhanced expression of CTalpha and CTbeta was observed. However, the expression of CTalpha or CTbeta was not increased in Ha-Ras-transformed cells transfected with a Sp3 plasmid presumably because expression was already maximally enhanced. The results suggest that Sp3 is a downstream effector of a Ras/p42/44(MAPK) signaling pathway which increases CTalpha gene transcription.
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Affiliation(s)
- Marica Bakovic
- Department of Biochemistry and Canadian Institutes of Health Research Group on Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta T6G 2S2, Canada
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29
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Lee SJ, Moye LA, Campos H, Williams GH, Sacks FM. Hypertriglyceridemia but not diabetes status is associated with VLDL containing apolipoprotein CIII in patients with coronary heart disease. Atherosclerosis 2003; 167:293-302. [PMID: 12818412 DOI: 10.1016/s0021-9150(03)00007-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
High apoCIII concentration in apoB lipoproteins is a prominent component of atherogenic dyslipidemia, and explains the risk of coronary heart disease (CHD) associated with high triglyceride (TG). We hypothesized that diabetic people have atherogenic dyslipidemia with apoCIII in excess of that accounted for by their high TG levels. We selected 30 diabetic and 30 nondiabetic persons, 15 of each with fasting TG<160 mg/dl and 15 with TG>/=200 mg/dl. Using immunoaffinity chromatography and ultracentrifugation, we prepared large and small VLDL, IDL and LDL with or without apoCIII or apoE. The groups with TG>/=200 mg/dl, regardless of diabetes status, had higher concentrations of large and small VLDL particles with apoCIII and higher apoCIII concentrations than the groups with fasting TG<160 mg/dl. The diabetes groups did not have higher concentrations of these lipoproteins than the nondiabetes groups within the same fasting TG criteria. In conclusion, high concentrations of apoCIII-containing VLDL are associated with hypertriglyceridemia, which may play a critical role in identifying the high risk of CHD in hypertriglyceridemic patients whether diabetic or nondiabetic. Diabetes status per se does not appear to be associated with high concentrations of apoCIII-containing TG-rich lipoprotein particles, if the plasma TG levels are similar.
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Affiliation(s)
- Sung-Joon Lee
- Department of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA
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30
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Beigneux AP, Moser AH, Shigenaga JK, Grunfeld C, Feingold KR. Sick euthyroid syndrome is associated with decreased TR expression and DNA binding in mouse liver. Am J Physiol Endocrinol Metab 2003; 284:E228-36. [PMID: 12388159 DOI: 10.1152/ajpendo.00155.2002] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Infection is associated with low serum thyroid hormones and thyrotropin levels. Here we demonstrate that infection also reduces thyroid hormone receptor (TR) expression. In gel shift experiments, retinoid X receptor (RXR)/TR DNA binding was reduced in mouse liver by 60 and 77%, respectively, 4 and 16 h after lipopolysaccharide (LPS) administration. Surprisingly, LPS did not decrease either TR-alpha or TR-beta protein levels at 4 h, but by 16 h TR-alpha(1), TR-alpha(2), and TR-beta levels were reduced by 55, 87, and 41%, respectively. We previously reported that LPS rapidly decreases RXR protein levels in liver. Therefore, we added RXR-beta to hepatic nuclear extracts prepared 4 h after LPS treatment, which restored RXR/TR DNA binding to a level comparable to that of controls. A similar experiment conducted on extracts prepared 16 h after LPS administration did not restore RXR/TR DNA binding. We propose that decreased RXR expression is limiting for RXR/TR DNA binding at 4 h, whereas the reduction in both TR and RXR levels results in further decreased binding at 16 h.
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Affiliation(s)
- Anne P Beigneux
- Department of Medicine, University of California San Francisco, 94121, USA.
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31
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Katoh N. Relevance of apolipoproteins in the development of fatty liver and fatty liver-related peripartum diseases in dairy cows. J Vet Med Sci 2002; 64:293-307. [PMID: 12014573 DOI: 10.1292/jvms.64.293] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Most metabolic diseases in dairy cows occur during the peripartum period and are suggested to be derived from fatty liver initially developed during the nonlactating stage. Fatty liver is induced by hepatic uptake of nonesterified fatty acids that are released in excess by adipose tissues attributable to negative energy balance. The fatty accumulation leads to impairment of lipoprotein metabolism in the liver, and the impairment in turn influences other metabolic pathways in extrahepatic tissues such as the steroid hormone production by the corpus luteum. Detailed understanding of the impaired lipoprotein metabolism is crucial for elucidation of the mechanistic bases of the development of fatty liver and fatty liver-related peripartum diseases. This review summarizes results on evaluation of lipoprotein lipid and protein concentrations and enzyme activity in cows with fatty liver and those with ketosis, left displacement of the abomasum, milk fever, downer syndrome and retained placenta. Obtained data strongly suggest that decreases in serum concentrations of apolipoprotein B-100, apolipoprotein A-I and apolipoprotein C-III, a reduction in activity of lecithin:cholesterol acyltransferase and induction of haptoglobin and serum amyloid A are intimately related to the development of fatty liver and fatty liver-related diseases. Moreover, determination of the apolipoprotein concentrations and enzyme activity during the peripartum period is useful for early diagnoses of these diseases.
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Affiliation(s)
- Norio Katoh
- Hokkaido Research Station, National Institute of Animal Health, Sapporo, Japan
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32
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Abstract
Dietary polyunsaturated fatty acids (PUFAs) are a source of energy and structural components for cells. PUFAs also have dramatic effects on gene expression by regulating the activity or abundance of four families of transcription factor, including peroxisome proliferator activated receptor (PPAR) (alpha, beta and gamma), liver X receptors (LXRs) (alpha and beta), hepatic nuclear factor-4 (HNF-4)alpha and sterol regulatory element binding proteins (SREBPs) 1 and 2. These transcription factors play a major role in hepatic carbohydrate, fatty acid, triglyceride, cholesterol and bile acid metabolism. Non-esterified fatty acids or fatty acid metabolites bind to and regulate the activity of PPARs, LXRs and HNF-4. In contrast, PUFAs regulate the nuclear abundance of SREBPs by controlling the proteolytic processing of SREBP precursors, or regulating transcription of the SREBP-1c gene or turnover of mRNA(SREBP-1c). The n3 and n6 PUFAs are feed-forward activators of PPARs, while these same fatty acids are feedback inhibitors of LXRs and SREBPs. Saturated fatty acyl coenzyme A thioesters activate HNF-4 alpha, while coenzyme A thioesters of PUFAs antagonize HNF-4 alpha action. Understanding how fatty acids regulate the activity and abundance of these and other transcription factors will likely provide insight into the development of novel therapeutic strategies for better management of whole body lipid and cholesterol metabolism.
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Affiliation(s)
- Donald B Jump
- Department of Physiology, Michigan State University, East Lansing, Michigan 48824, USA.
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33
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Katoh N, Oikawa S, Oohashi T, Takahashi Y, Itoh F. Decreases of apolipoprotein B-100 and A-I concentrations and induction of haptoglobin and serum amyloid A in nonfed calves. J Vet Med Sci 2002; 64:51-5. [PMID: 11853146 DOI: 10.1292/jvms.64.51] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Reduced feed intake near parturition is suggested to be one of the major causal factors for the development of fatty liver in cows, and nonfeeding has been used as an experimental model for fatty liver. In cows with fatty liver, concentrations of lipoprotein lipids and proteins are decreased. In addition, the acute-phase protein haptoglobin is induced. The purpose of the present study was to examine whether the decrease of lipoprotein concentrations and the induction of acute-phase proteins were similarly reproduced by non-feeding. Holstein female calves (n=5) were nonfed for 3 days and thereafter refed. Serum concentrations of nonesterified fatty acids and beta-hydroxybutyric acid were initially increased by the nonfeeding, and followed by decreases in concentrations of cholesteryl esters, phospholipids, apolipoprotein (apo) B-100 and apoA-I. The apoC-III concentration was not distinctly decreased. Haptoglobin and serum amyloid A were induced during the nonfeeding and refeeding process. Haptoglobin was distributed in different proportions in the high-density lipoprotein, very high-density lipoprotein and the lipoprotein-deficient fractions, whereas almost all serum amyloid A was associated with the high-density lipoprotein fraction. These results suggest that the decreases in lipoprotein concentrations and induction of acute-phase proteins found in cows with fatty liver and those with fatty liver-related diseases such as ketosis are primarily due to the reduced feed intake near parturition.
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Affiliation(s)
- Norio Katoh
- Hokkaido Research Station, National Institute of Animal Health, Sapporo, Japan
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34
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Yang W, Hong YH, Shen XQ, Frankowski C, Camp HS, Leff T. Regulation of transcription by AMP-activated protein kinase: phosphorylation of p300 blocks its interaction with nuclear receptors. J Biol Chem 2001; 276:38341-4. [PMID: 11518699 DOI: 10.1074/jbc.c100316200] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AMP-activated protein kinase (AMP-kinase) modulates many metabolic processes in response to fluctuations in cellular energy status. Although most of its known targets are metabolic enzymes, it has been proposed that AMP-kinase might also regulate gene expression. Here we demonstrate that the transcriptional coactivator p300 is a substrate of AMP-kinase. Phosphorylation of p300 at serine 89 by AMP-kinase dramatically reduced its interaction, in vitro and in vivo, with the nuclear receptors peroxisome proliferator-activated receptor gamma, thyroid receptor, retinoic acid receptor, and retinoid X receptor, but did not affect its interaction with the non-nuclear receptor transcription factors E1a, p53, or GATA4. These findings indicate that the AMP-kinase signaling pathway selectively modulates a subset of p300 activities and represent the first example of a transcriptional component regulated by AMP-kinase. Our results suggest a direct link between cellular energy metabolism and gene expression.
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Affiliation(s)
- W Yang
- Department of Molecular Sciences, Pfizer Global Research and Development, Ann Arbor, Michigan 48105, USA
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35
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Osawa Y, Nagaki M, Banno Y, Nozawa Y, Moriwaki H, Nakashima S. Sphingosine kinase regulates hepatoma cell differentiation: roles of hepatocyte nuclear factor and retinoid receptor. Biochem Biophys Res Commun 2001; 286:673-7. [PMID: 11520048 DOI: 10.1006/bbrc.2001.5451] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In hepatoma Huh-7 cells, inhibition of sphingosine kinase (SphK) activity by N,N-dimethylsphingosine (DMS) resulted in up-regulated production of liver-specific serum proteins including albumin and alpha-fetoprotein (AFP). The changes in these protein levels coincided well with those of two liver-enriched transcription factors, hepatocyte nuclear factor (HNF)-1 and -4, which regulate a number of liver-specific genes at the transcriptional level. Moreover, DMS induced the expression of retinoic acid receptor-alpha and retinoid X receptor-alpha. In DMS-treated cells, 9-cis retinoic acid (RA) further enhanced HNF-4alpha and albumin expression but it inhibited AFP accumulation. These results suggest that activation of SphK disengages cells from their liver-specific phenotype, and that 9-cis RA further induces differentiation of hepatoma cells when SphK activity is inhibited.
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Affiliation(s)
- Y Osawa
- First Department of Internal Medicine, Gifu University School of Medicine, Tsukasamachi-40, Gifu 500-8705, Japan
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36
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Abstract
Apolipoprotein (apo)C-I and apoC-III are constituents of HDL and of triglyceride-rich lipoproteins that slow the clearance of triglyceride-rich lipoproteins by a variety of mechanisms. ApoC-I is an inhibitor of lipoprotein binding to the LDL receptor, LDL receptor-related protein, and VLDL receptor. It also is the major plasma inhibitor of cholesteryl ester transfer protein, and appears to interfere directly with fatty acid uptake. ApoC-III also interferes with lipoprotein particle clearance, but its principal role is as an inhibitor of lipolysis, both through the biochemical inhibition of lipoprotein lipase and by interfering with lipoprotein binding to the cell-surface glycosaminoglycan matrix where lipolytic enzymes and lipoprotein receptors reside. Variation in the expression of apoC-III has been credibly documented to have an important role in hypertriglyceridemia. Variation in the expression of apoC-I may also be important for hypertriglyceridemia under certain circumstances.
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Affiliation(s)
- N S Shachter
- Divisions of Preventive Medicine and Nutrition, and Cardiology, Columbia University, New York, New York 10032-3702, USA.
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37
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Zannis VI, Kan HY, Kritis A, Zanni EE, Kardassis D. Transcriptional regulatory mechanisms of the human apolipoprotein genes in vitro and in vivo. Curr Opin Lipidol 2001; 12:181-207. [PMID: 11264990 DOI: 10.1097/00041433-200104000-00012] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The present review summarizes recent advances in the transcriptional regulation of the human apolipoprotein genes, focusing mostly, but not exclusively, on in-vivo studies and signaling mechanisms that affect apolipoprotein gene transcription. An attempt is made to explain how interactions of transcription factors that bind to proximal promoters and distal enhancers may bring about gene transcription. The experimental approaches used and the transcriptional regulatory mechanisms that emerge from these studies may also be applicable in other gene systems that are associated with human disease. Understanding extracellular stimuli and the specific mechanisms that underlie apolipoprotein gene transcription may in the long run allow us to selectively switch on antiatherogenic genes, and switch off proatherogenic genes. This may have beneficial effects and may confer protection from atherosclerosis to humans.
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Affiliation(s)
- V I Zannis
- Section of Molecular Genetics, Whitaker Cardiovascular Institute, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118-2394, USA.
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Yamamoto M, Nakagawa-Ueta H, Katoh N, Oikawa S. Decreased concentration of serum apolipoprotein C-III in cows with fatty liver, ketosis, left displacement of the abomasum, milk fever and retained placenta. J Vet Med Sci 2001; 63:227-31. [PMID: 11307920 DOI: 10.1292/jvms.63.227] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Apolipoprotein (apo) C-III is a low molecular mass protein mainly distributed in the high-density lipoprotein (HDL) fraction. In cows with postparturient diseases such as ketosis, concentrations of cholesterol, phospholipids and apoA-I and the activity of lecithin:cholesterol acyltransferase, which are mainly distributed in or functionally associated with HDL, are reduced. The purpose of the present study was to examine whether the serum concentration of apoC-III was similarly decreased in the postparturient diseases. Compared with healthy controls, the apoC-III concentration was significantly (P<0.01) decreased in cows with fatty liver, ketosis, left displacement of the abomasum, milk fever and retained placenta. Concentrations of apoC-III in the HDL fractions from diseased cows were also lower than in controls. Of the diseased cows, the decreased apoC-III concentration was particularly distinct in cows with milk fever. Increased nonesterified fatty acid and reduced free cholesterol, cholesteryl ester and phospholipid concentrations were observed in cows with milk fever, as in the other diseased cows. The decrease in the apoC-III concentration is suggested to be closely associated with the postparturient disorders, in particular with milk fever.
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Affiliation(s)
- M Yamamoto
- The Fukushima Kenchu Livestock Hygiene Service Center, Kooriyama, Japan
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Hernandez A, Smith F, Wang Q, Wang X, Evers BM. Assessment of differential gene expression patterns in human colon cancers. Ann Surg 2000; 232:576-85. [PMID: 10998656 PMCID: PMC1421190 DOI: 10.1097/00000658-200010000-00013] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE To use a novel genomic approach to determine differential gene expression patterns in colon cancers of different metastatic potential. SUMMARY BACKGROUND DATA Colorectal cancer is the third leading cause of cancer deaths in the United States; despite aggressive treatment strategies, the 5-year survival rate for metastatic cancer has not changed in 50 years. The analysis of changes in gene expression patterns associated with metastasis may provide new treatment strategies. METHODS Human colon cancer cells KM12C (derived from a Dukes B colon cancer), KML4A (a metastatic variant derived from KM12C), and KM20 (derived from a Dukes D colon cancer) were extracted for RNA. In addition, RNA was extracted from normal colon, primary cancer, and liver metastasis in a patient with metastatic colon cancer. Gene expression patterns for approximately 1,200 human genes were analyzed and compared by cDNA array techniques. RESULTS Of the roughly 1,200 genes assessed in the KM cell lines, 9 genes were noted to have a more than threefold change in expression (either increased or decreased) in the more metastatic KML4A and KM20 cells compared with KM12C. Assessment of tissues from a patient with metastatic colon cancer demonstrated a more than threefold change in the expression of 14 genes in the primary cancer and liver metastasis compared with normal mucosa. CONCLUSIONS Using cDNA expression array technology, the authors identified genes with expression levels that are altered with metastasis. The ability to analyze and compare the expression patterns of multiple genes simultaneously provides a powerful technique to identify potential molecular targets for novel therapeutic strategies.
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Affiliation(s)
- A Hernandez
- Department of Surgery, The University of Texas Medical Branch, Galveston, Texas 77555-0536, USA
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40
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Beigneux AP, Moser AH, Shigenaga JK, Grunfeld C, Feingold KR. The acute phase response is associated with retinoid X receptor repression in rodent liver. J Biol Chem 2000; 275:16390-9. [PMID: 10747970 DOI: 10.1074/jbc.m000953200] [Citation(s) in RCA: 183] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The acute phase response (APR) is associated with decreased hepatic expression of many proteins involved in lipid metabolism. The nuclear hormone receptors peroxisome proliferator-activated receptor alpha (PPARalpha) and liver X receptor (LXR) play key roles in regulation of hepatic lipid metabolism. Because heterodimerization with RXR is crucial for their action, we hypothesized that a decrease in RXR may be one mechanism to coordinately down-regulate gene expression during APR. We demonstrate that lipopolysaccharide (LPS) induces a rapid, dose-dependent decrease in RXRalpha, RXRbeta, and RXRgamma proteins in hamster liver. Maximum inhibition was observed at 4 h for RXRalpha (62%) and RXRbeta (50%) and at 2 h for RXRgamma (61%). These decreases were associated with a marked reduction in RXRalpha, RXRbeta, and RXRgamma mRNA levels. Increased RNA degradation is likely responsible for the repression of RXR, because LPS did not decrease RXRbeta and RXRgamma transcription and only marginally inhibited (38%) RXRalpha transcription. RXR repression was associated with decreased LXRalpha and PPARalpha mRNA levels and reduced RXR x RXR, RXR x PPAR and RXR x LXR binding activities in nuclear extracts. Furthermore, LPS markedly decreased both basal and Wy-14,643-induced expression of acyl-CoA synthetase, a well characterized PPARalpha target. The reduction in hepatic RXR levels alone or in association with other nuclear hormone receptors could be a mechanism for coordinately inhibiting the expression of multiple genes during the APR.
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Affiliation(s)
- A P Beigneux
- Department of Medicine, University of California San Francisco, Metabolism Section, Medical Service, Department of Veterans Affairs Medical Center, San Francisco, California 94121, USA
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Pan DA, Mater MK, Thelen AP, Peters JM, Gonzalez FJ, Jump DB. Evidence against the peroxisome proliferator-activated receptor α (PPARα) as the mediator for polyunsaturated fatty acid suppression of hepatic L-pyruvate kinase gene transcription. J Lipid Res 2000. [DOI: 10.1016/s0022-2275(20)32383-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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