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Cheng Z, Chen Y, Schnabl B, Chu H, Yang L. Bile acid and nonalcoholic steatohepatitis: Molecular insights and therapeutic targets. J Adv Res 2024; 59:173-187. [PMID: 37356804 PMCID: PMC11081971 DOI: 10.1016/j.jare.2023.06.009] [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: 03/30/2023] [Revised: 06/06/2023] [Accepted: 06/20/2023] [Indexed: 06/27/2023] Open
Abstract
BACKGROUND Nonalcoholic steatohepatitis (NASH) has been the second most common cause of liver transplantation in the United States. To date, NASH pathogenesis has not been fully elucidated but is multifactorial, involving insulin resistance, obesity, metabolic disorders, diet, dysbiosis, and gene polymorphism. An effective and approved therapy for NASH has also not been established. Bile acid is long known to have physiological detergent function in emulsifying and absorbing lipids and lipid-soluble molecules within the intestinal lumen. With more and more in-depth understandings of bile acid, it has been deemed to be a pivotal signaling molecule, which is capable of regulating lipid and glucose metabolism, liver inflammation, and fibrosis. In recent years, a plethora of studies have delineated that disrupted bile acid homeostasis is intimately correlated with NASH disease severity. AIMS The review aims to clarify the role of bile acid in hepatic lipid and glucose metabolism, liver inflammation, as well as liver fibrosis, and discusses the safety and efficacy of some pharmacological agents targeting bile acid and its associated pathways for NASH. KEY SCIENTIFIC CONCEPTS OF REVIEW Bile acid has a salutary effect on hepatic metabolic disorders, which can ameliorate liver fat accumulation and insulin resistance mainly through activating Takeda G-protein coupled receptor 5 and farnesoid X receptor. Moreover, bile acid also exerts anti-inflammation and anti-fibrosis properties. Furthermore, bile acid has great potential in nonalcoholic liver disease stratification and treatment of NASH.
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Affiliation(s)
- Zilu Cheng
- Division of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei Province 430022, China
| | - Yixiong Chen
- Division of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei Province 430022, China
| | - Bernd Schnabl
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Huikuan Chu
- Division of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei Province 430022, China.
| | - Ling Yang
- Division of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei Province 430022, China.
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2
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Xiao Y, Wang W, Peng S, Lu Y, Du J, Cai W. Farnesoid X receptor agonist tropifexor detoxifies ammonia by regulating the glutamine metabolism and urea cycles in cholestatic livers. Eur J Pharmacol 2024; 966:176334. [PMID: 38286357 DOI: 10.1016/j.ejphar.2024.176334] [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: 10/10/2023] [Revised: 12/14/2023] [Accepted: 01/16/2024] [Indexed: 01/31/2024]
Abstract
Hyperammonemia refers to elevated levels of ammonia in the blood, which is an important pathological feature of liver cirrhosis and hepatic failure. Preclinical studies suggest tropifexor (TXR), a novel non-bile acid agonist of Farnesoid X Receptor (FXR), has shown promising effects on reducing hepatic steatosis, inflammation, and fibrosis. This study evaluates the impact of TXR on hyperammonemia in a piglet model of cholestasis. We here observed blood ammonia significantly elevated in patients with biliary atresia (BA) and was positively correlated with liver injury. Targeted metabolomics and immunblotting showed glutamine metabolism and urea cycles were impaired in BA patients. Next, we observed that TXR potently suppresses bile duct ligation (BDL)-induced injuries in liver and brain with improving the glutamine metabolism and urea cycles. Within the liver, TXR enhances glutamine metabolism and urea cycles by up-regulation of key regulatory enzymes, including glutamine synthetase (GS), carbamoyl-phosphate synthetase 1 (CPS1), argininosuccinate synthetase (ASS1), argininosuccinate lyase (ASL), and arginase 1 (ARG1). In primary mice hepatocytes, TXR detoxified ammonia via increasing ureagenesis. Mechanically, TXR activating FXR to increase express enzymes that regulating ureagenesis and glutamine synthesis through a transcriptional approach. Together, these results suggest that TXR may have therapeutic implications for hyperammonemic conditions in cholestatic livers.
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Affiliation(s)
- Yongtao Xiao
- Department of Pediatric Surgery, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Division of Pediatric Gastroenterology and Nutrition, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute of Pediatric Research, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China.
| | - Weipeng Wang
- Department of Pediatric Surgery, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
| | - Shicheng Peng
- Shanghai Institute of Pediatric Research, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
| | - Ying Lu
- Shanghai Institute of Pediatric Research, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
| | - Jun Du
- Shanghai Institute of Pediatric Research, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
| | - Wei Cai
- Department of Pediatric Surgery, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Division of Pediatric Gastroenterology and Nutrition, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute of Pediatric Research, Shanghai, China; Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China.
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3
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Hu Y, Setayesh T, Vaziri F, Wu X, Hwang ST, Chen X, Yvonne Wan YJ. miR-22 gene therapy treats HCC by promoting anti-tumor immunity and enhancing metabolism. Mol Ther 2023; 31:1829-1845. [PMID: 37143325 PMCID: PMC10277895 DOI: 10.1016/j.ymthe.2023.04.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 03/29/2023] [Accepted: 04/28/2023] [Indexed: 05/06/2023] Open
Abstract
MicroRNA-22 (miR-22) can be induced by beneficial metabolites that have metabolic and immune effects, including retinoic acids, bile acids, vitamin D3, and short-chain fatty acids. The tumor suppressor effects of miR-22 have been suggested, but whether miR-22 treats orthotopic hepatocellular carcinoma (HCC) is not established. The role of miR-22 in regulating tumor immunity is also poorly understood. Our data showed that miR-22 delivered by adeno-associated virus serotype 8 effectively treated HCC. Compared with FDA-approved lenvatinib, miR-22 produced better survival outcomes without noticeable toxicity. miR-22 silenced hypoxia-inducible factor 1 (HIF1α) and enhanced retinoic acid signaling in both hepatocytes and T cells. Moreover, miR-22 treatment improved metabolism and reduced inflammation. In the liver, miR-22 reduced the abundance of IL17-producing T cells and inhibited IL17 signaling by reducing the occupancy of HIF1α in the Rorc and Il17a genes. Conversely, increasing IL17 signaling ameliorated the anti-HCC effect of miR-22. Additionally, miR-22 expanded cytotoxic T cells and reduced regulatory T cells (Treg). Moreover, depleting cytotoxic T cells also abolished the anti-HCC effects of miR-22. In patients, miR-22 high HCC had upregulated metabolic pathways and reduced IL17 pro-inflammatory signaling compared with miR-22 low HCC. Together, miR-22 gene therapy can be a novel option for HCC treatment.
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Affiliation(s)
- Ying Hu
- Department of Pathology and Laboratory Medicine, University of California Davis Health, Sacramento, CA 95817, USA
| | - Tahereh Setayesh
- Department of Pathology and Laboratory Medicine, University of California Davis Health, Sacramento, CA 95817, USA
| | - Farzam Vaziri
- Department of Pathology and Laboratory Medicine, University of California Davis Health, Sacramento, CA 95817, USA
| | - Xuesong Wu
- Department of Dermatology, University of California Davis Health, Sacramento, CA 95817, USA
| | - Samuel T Hwang
- Department of Dermatology, University of California Davis Health, Sacramento, CA 95817, USA
| | - Xin Chen
- Cancer Biology Program, University of Hawaii Cancer Center, Honolulu, HI 96813, USA
| | - Yu-Jui Yvonne Wan
- Department of Pathology and Laboratory Medicine, University of California Davis Health, Sacramento, CA 95817, USA.
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Taylor R, Armstrong L, Bhattacharya A, Henry Z, Brinker A, Buckley B, Kong B, Guo G. Myclobutanil-mediated alteration of liver-gut FXR signaling in mice. Toxicol Sci 2023; 191:387-399. [PMID: 36511616 PMCID: PMC9936201 DOI: 10.1093/toxsci/kfac129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The effects of exposure to Myclobutanil, a triazole fungicide, on the development and progression of nonalcoholic fatty liver disease (NAFLD) are unclear, but activation of nuclear receptors (NRs) is a known mechanism of azole-induced liver toxicity. Farnesoid X receptor (FXR) is a NR and is highly expressed in the liver and intestine. Activation of FXR tightly regulates bile acid (BA), lipid and glucose homeostasis, and inflammation partly through the induction of fibroblast growth factor 15 (FGF15; human ortholog FGF19). FXR activation is downregulated during NAFLD and agonists are currently being explored as potential therapeutic strategy. In this study, we aimed to clarify the effects of Myclobutanil exposure on FXR activation and NAFLD development. Reporter assay showed Myclobutanil treatment, following FXR activation with potent FXR agonist (GW4064), resulted in a dose-dependent decrease of FXR activity. Furthermore, a 10-day study in male mice demonstrated that cotreatment with Myclobutanil led to an 80% reduction of GW4064-induced ileal expression of Fgf15. In a diet-induced NAFLD study, low-fat diet (LFD) fed mice administered myclobutanil displayed decreased FXR activity in the liver and ileum, while high-fat-high-sugar-diet (HFHSD) fed mice showed an increase in hepatic FXR activity and an induction of target genes regulated by constitutive androstane receptor and/or pregnane X receptor. Our work demonstrates Myclobutanil inhibits FXR activity and modulates FXR activity differentially in mice fed LFD or HFHSD. Our studies suggest the importance of understanding how Myclobutanil could contribute to BA dysregulation in disease states such as NAFLD.
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Affiliation(s)
- Rulaiha Taylor
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ 08854, USA.,Environmental and Occupational Health Science Institute, Rutgers University, Piscataway, NJ 08854, USA.,Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
| | - Laura Armstrong
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ 08854, USA.,Environmental and Occupational Health Science Institute, Rutgers University, Piscataway, NJ 08854, USA.,Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
| | - Anisha Bhattacharya
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ 08854, USA
| | - Zakiyah Henry
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ 08854, USA.,Environmental and Occupational Health Science Institute, Rutgers University, Piscataway, NJ 08854, USA.,Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
| | - Anita Brinker
- Environmental and Occupational Health Science Institute, Rutgers University, Piscataway, NJ 08854, USA
| | - Brian Buckley
- Environmental and Occupational Health Science Institute, Rutgers University, Piscataway, NJ 08854, USA
| | - Bo Kong
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ 08854, USA.,Environmental and Occupational Health Science Institute, Rutgers University, Piscataway, NJ 08854, USA.,Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA
| | - Grace Guo
- Department of Pharmacology and Toxicology, Rutgers University, Piscataway, NJ 08854, USA.,Environmental and Occupational Health Science Institute, Rutgers University, Piscataway, NJ 08854, USA.,Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ 08901, USA.,VA New Jersey Health Care System, Veterans Administration Medical Center, East Orange, NJ 07017, USA
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5
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Kim DH, Park JS, Choi HI, Kim CS, Bae EH, Ma SK, Kim SW. The role of the farnesoid X receptor in kidney health and disease: a potential therapeutic target in kidney diseases. Exp Mol Med 2023; 55:304-312. [PMID: 36737665 PMCID: PMC9981614 DOI: 10.1038/s12276-023-00932-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/22/2022] [Accepted: 12/01/2022] [Indexed: 02/05/2023] Open
Abstract
The prevalence of kidney diseases has been increasing worldwide due to the aging population and has results in an increased socioeconomic burden as well as increased morbidity and mortality. A deep understanding of the mechanisms underlying the physiological regulation of the kidney and the pathogenesis of related diseases can help identify potential therapeutic targets. The farnesoid X receptor (FXR, NR1H4) is a primary nuclear bile acid receptor that transcriptionally regulates bile acid homeostasis as well as glucose and lipid metabolism in multiple tissues. The roles of FXR in tissues other than hepatic and intestinal tissues are poorly understood. In studies over the past decade, FXR has been demonstrated to have a protective effect against kidney diseases through its anti-inflammatory and antifibrotic effects; it also plays roles in glucose and lipid metabolism in the kidney. In this review, we discuss the physiological role of FXR in the kidney and its pathophysiological roles in various kidney diseases, including acute kidney injury and chronic kidney diseases, diabetic nephropathy, and kidney fibrosis. Therefore, the regulatory mechanisms involving nuclear receptors, such as FXR, in the physiology and pathophysiology of the kidney and the development of agonists and antagonists for modulating FXR expression and activation should be elucidated to identify therapeutic targets for the treatment of kidney diseases.
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Affiliation(s)
- Dong-Hyun Kim
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, 61469, Korea.
| | - Jung Sun Park
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, 61469, Korea
| | - Hoon-In Choi
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, 61469, Korea
| | - Chang Seong Kim
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, 61469, Korea
| | - Eun Hui Bae
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, 61469, Korea
| | - Seong Kwon Ma
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, 61469, Korea
| | - Soo Wan Kim
- Department of Internal Medicine, Chonnam National University Medical School, Gwangju, 61469, Korea.
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6
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Di Ciaula A, Bonfrate L, Baj J, Khalil M, Garruti G, Stellaard F, Wang HH, Wang DQH, Portincasa P. Recent Advances in the Digestive, Metabolic and Therapeutic Effects of Farnesoid X Receptor and Fibroblast Growth Factor 19: From Cholesterol to Bile Acid Signaling. Nutrients 2022; 14:nu14234950. [PMID: 36500979 PMCID: PMC9738051 DOI: 10.3390/nu14234950] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 11/18/2022] [Accepted: 11/20/2022] [Indexed: 11/23/2022] Open
Abstract
Bile acids (BA) are amphiphilic molecules synthesized in the liver (primary BA) starting from cholesterol. In the small intestine, BA act as strong detergents for emulsification, solubilization and absorption of dietary fat, cholesterol, and lipid-soluble vitamins. Primary BA escaping the active ileal re-absorption undergo the microbiota-dependent biotransformation to secondary BA in the colon, and passive diffusion into the portal vein towards the liver. BA also act as signaling molecules able to play a systemic role in a variety of metabolic functions, mainly through the activation of nuclear and membrane-associated receptors in the intestine, gallbladder, and liver. BA homeostasis is tightly controlled by a complex interplay with the nuclear receptor farnesoid X receptor (FXR), the enterokine hormone fibroblast growth factor 15 (FGF15) or the human ortholog FGF19 (FGF19). Circulating FGF19 to the FGFR4/β-Klotho receptor causes smooth muscle relaxation and refilling of the gallbladder. In the liver the binding activates the FXR-small heterodimer partner (SHP) pathway. This step suppresses the unnecessary BA synthesis and promotes the continuous enterohepatic circulation of BAs. Besides BA homeostasis, the BA-FXR-FGF19 axis governs several metabolic processes, hepatic protein, and glycogen synthesis, without inducing lipogenesis. These pathways can be disrupted in cholestasis, nonalcoholic fatty liver disease, and hepatocellular carcinoma. Thus, targeting FXR activity can represent a novel therapeutic approach for the prevention and the treatment of liver and metabolic diseases.
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Affiliation(s)
- Agostino Di Ciaula
- Clinica Medica “A. Murri”, Department of Biomedical Sciences & Human Oncology, University of Bari “Aldo Moro” Medical School, 70124 Bari, Italy
| | - Leonilde Bonfrate
- Clinica Medica “A. Murri”, Department of Biomedical Sciences & Human Oncology, University of Bari “Aldo Moro” Medical School, 70124 Bari, Italy
| | - Jacek Baj
- Department of Anatomy, Medical University of Lublin, 20-059 Lublin, Poland
| | - Mohamad Khalil
- Clinica Medica “A. Murri”, Department of Biomedical Sciences & Human Oncology, University of Bari “Aldo Moro” Medical School, 70124 Bari, Italy
| | - Gabriella Garruti
- Section of Endocrinology, Department of Emergency and Organ Transplantations, University of Bari “Aldo Moro” Medical School, 70124 Bari, Italy
| | - Frans Stellaard
- Institute of Clinical Chemistry and Clinical Pharmacology, Venusberg-Campus 1, University Hospital Bonn, 53127 Bonn, Germany
| | - Helen H. Wang
- Department of Medicine and Genetics, Division of Gastroenterology and Liver Diseases, Marion Bessin Liver Research Center, Einstein-Mount Sinai Diabetes Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - David Q.-H. Wang
- Department of Medicine and Genetics, Division of Gastroenterology and Liver Diseases, Marion Bessin Liver Research Center, Einstein-Mount Sinai Diabetes Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Piero Portincasa
- Clinica Medica “A. Murri”, Department of Biomedical Sciences & Human Oncology, University of Bari “Aldo Moro” Medical School, 70124 Bari, Italy
- Correspondence: ; Tel.: +39-328-4687215
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7
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Molecular Basis of Bile Acid-FXR-FGF15/19 Signaling Axis. Int J Mol Sci 2022; 23:ijms23116046. [PMID: 35682726 PMCID: PMC9181207 DOI: 10.3390/ijms23116046] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 02/04/2023] Open
Abstract
Bile acids (BAs) are a group of amphiphilic molecules consisting of a rigid steroid core attached to a hydroxyl group with a varying number, position, and orientation, and a hydrophilic side chain. While BAs act as detergents to solubilize lipophilic nutrients in the small intestine during digestion and absorption, they also act as hormones. Farnesoid X receptor (FXR) is a nuclear receptor that forms a heterodimer with retinoid X receptor α (RXRα), is activated by BAs in the enterohepatic circulation reabsorbed via transporters in the ileum and the colon, and plays a critical role in regulating gene expression involved in cholesterol, BA, and lipid metabolism in the liver. The FXR/RXRα heterodimer also exists in the distal ileum and regulates production of fibroblast growth factor (FGF) 15/FGF19, a hormone traveling via the enterohepatic circulation that activates hepatic FGF receptor 4 (FGFR4)-β-klotho receptor complex and regulates gene expression involved in cholesterol, BA, and lipid metabolism, as well as those regulating cell proliferation. Agonists for FXR and analogs for FGF15/19 are currently recognized as a promising therapeutic target for metabolic syndrome and cholestatic diseases.
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Taylor RE, Bhattacharya A, Guo GL. Environmental Chemical Contribution to the Modulation of Bile Acid Homeostasis and Farnesoid X Receptor Signaling. Drug Metab Dispos 2022; 50:456-467. [PMID: 34759011 PMCID: PMC11022932 DOI: 10.1124/dmd.121.000388] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 11/05/2021] [Indexed: 11/22/2022] Open
Abstract
Maintaining bile acid (BA) homeostasis is important and regulated by BA activated receptors and signaling pathways. Farnesoid X receptor (FXR) and its regulated target networks in both the liver and the intestines are critical in suppressing BA synthesis and promoting BA transport and enterohepatic circulation. In addition, FXR is critical in regulating lipid metabolism and reducing inflammation, processes critical in the development of cholestasis and fatty liver diseases. BAs are modulated by, but also control, gut microflora. Environmental chemical exposure could affect liver disease development. However, the effects and the mechanisms by which environmental chemicals interact with FXR to affect BA homeostasis are only emerging. In this minireview, our focus is to provide evidence from reports that determine the effects of environmental or therapeutic exposure on altering homeostasis and functions of BAs and FXR. Understanding these effects will help to determine liver disease pathogenesis and provide better prevention and treatment in the future. SIGNIFICANCE STATEMENT: Environmental chemical exposure significantly contributes to the development of cholestasis and nonalcoholic steatohepatitis (NASH). The impact of exposures on bile acid (BA) signaling and Farnesoid X receptor-mediated gut-liver crosstalk is emerging. However, there is still a huge gap in understanding how these chemicals contribute to the dysregulation of BA homeostasis and how this dysregulation may promote NASH development.
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Affiliation(s)
- Rulaiha E Taylor
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, New Jersey (R.E.T., A.B., G.L.G.); Environmental and Occupational Health Sciences Institute, Rutgers, The State University of New Jersey, Piscataway, New Jersey (G.L.G.); Rutgers Center for Lipid Research, Rutgers, The State University of New Jersey, New Brunswick, New Jersey (G.L.G.); and VA New Jersey Health Care System, Veterans Administration Medical Center, East Orange, New Jersey (G.L.G.)
| | - Anisha Bhattacharya
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, New Jersey (R.E.T., A.B., G.L.G.); Environmental and Occupational Health Sciences Institute, Rutgers, The State University of New Jersey, Piscataway, New Jersey (G.L.G.); Rutgers Center for Lipid Research, Rutgers, The State University of New Jersey, New Brunswick, New Jersey (G.L.G.); and VA New Jersey Health Care System, Veterans Administration Medical Center, East Orange, New Jersey (G.L.G.)
| | - Grace L Guo
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, New Jersey (R.E.T., A.B., G.L.G.); Environmental and Occupational Health Sciences Institute, Rutgers, The State University of New Jersey, Piscataway, New Jersey (G.L.G.); Rutgers Center for Lipid Research, Rutgers, The State University of New Jersey, New Brunswick, New Jersey (G.L.G.); and VA New Jersey Health Care System, Veterans Administration Medical Center, East Orange, New Jersey (G.L.G.)
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9
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Farnesoid X Receptor Deficiency Induces Hepatic Lipid and Glucose Metabolism Disorder via Regulation of Pyruvate Dehydrogenase Kinase 4. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:3589525. [PMID: 35251469 PMCID: PMC8896157 DOI: 10.1155/2022/3589525] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 01/18/2022] [Accepted: 02/01/2022] [Indexed: 12/19/2022]
Abstract
Farnesoid X receptors (FXR) are bile acid receptors that play roles in lipid, glucose, and energy homeostasis. Synthetic FXR-specific agonists have been developed for treating nonalcoholic fatty liver disease (NAFLD) patients. However, the detailed mechanism remains unclear. To investigate the effects of FXR on NAFLD and the possible mechanism, FXR-null mice were fed either a normal or a high-fat diet. The FXR-null mice developed hepatomegaly, steatosis, accumulation of lipid droplets in liver cells, glucose metabolism disorder, and elevated serum lipid levels. Transcriptomic results showed increased expression of key lipid synthesis and glucose metabolism-related proteins. We focused on pyruvate dehydrogenase kinase 4 (PDK4), a key enzyme involved in the regulation of glucose and fatty acid (FA) metabolism and homeostasis. Subsequently, we confirmed an increase in PDK4 expression in FXR knockout cells. Moreover, inhibition of PDK4 expression alleviated lipid accumulation in hepatocytes caused by FXR deficiency in vivo and in vitro. Our results identify FXR as a nuclear transcription factor that regulates glucose and lipid metabolism balance through PDK4, providing further insights into the mechanism of FXR agonists in the treatment of metabolic diseases.
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10
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Jungwirth E, Panzitt K, Marschall HU, Thallinger GG, Wagner M. Meta-analysis and Consolidation of Farnesoid X Receptor Chromatin Immunoprecipitation Sequencing Data Across Different Species and Conditions. Hepatol Commun 2021; 5:1721-1736. [PMID: 34558825 PMCID: PMC8485886 DOI: 10.1002/hep4.1749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 04/25/2021] [Indexed: 12/24/2022] Open
Abstract
Farnesoid X receptor (FXR) is a nuclear receptor that controls gene regulation of different metabolic pathways and represents an upcoming drug target for various liver diseases. Several data sets on genome-wide FXR binding in different species and conditions exist. We have previously reported that these data sets are heterogeneous and do not cover the full spectrum of potential FXR binding sites. Here, we report the first meta-analysis of all publicly available FXR chromatin immunoprecipitation sequencing (ChIP-seq) data sets from mouse, rat, and human across different conditions using a newly generated analysis pipeline. All publicly available single data sets were biocurated in a standardized manner and compared on every relevant level from raw reads to affected functional pathways. Individual murine data sets were then virtually merged into a single unique "FXR binding atlas" spanning all potential binding sites across various conditions. Comparison of the single biocurated data sets showed that the overlap of FXR binding sites between different species is modest and ranges from 48% (mouse-human) to 55% (mouse-rat). Moreover, in vivo data among different species are more similar than human in vivo data compared to human in vitro data. The consolidated murine global FXR binding atlas virtually increases sequencing depth and allows recovering more and novel potential binding sites and signaling pathways that were missed in the individual data sets. The FXR binding atlas is publicly searchable (https://fxratlas.tugraz.at). Conclusion: Published single FXR ChIP-seq data sets and large-scale integrated omics data sets do not cover the full spectrum of FXR binding. Combining different individual data sets and creating an "FXR super-binding atlas" enhances understanding of FXR signaling capacities across different conditions. This is important when considering the potential wide spectrum for drugs targeting FXR in liver diseases.
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Affiliation(s)
- Emilian Jungwirth
- Research Unit for Translational Nuclear Receptor ResearchDivision of Gastroenterology and HepatologyMedical University GrazGrazAustria.,Institute of Biomedical InformaticsGraz University of TechnologyGrazAustria.,OMICS Center GrazGrazAustria.,BioTechMed-GrazGrazAustria
| | - Katrin Panzitt
- Research Unit for Translational Nuclear Receptor ResearchDivision of Gastroenterology and HepatologyMedical University GrazGrazAustria
| | - Hanns-Ulrich Marschall
- Department of Molecular and Clinical Medicine/Wallenberg LaboratorySahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Gerhard G Thallinger
- Institute of Biomedical InformaticsGraz University of TechnologyGrazAustria.,OMICS Center GrazGrazAustria.,BioTechMed-GrazGrazAustria
| | - Martin Wagner
- Research Unit for Translational Nuclear Receptor ResearchDivision of Gastroenterology and HepatologyMedical University GrazGrazAustria.,OMICS Center GrazGrazAustria.,BioTechMed-GrazGrazAustria
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11
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Mustonen EK, Lee SML, Nieß H, Schwab M, Pantsar T, Burk O. Identification and characterization of novel splice variants of human farnesoid X receptor. Arch Biochem Biophys 2021; 705:108893. [PMID: 33930378 DOI: 10.1016/j.abb.2021.108893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 02/02/2023]
Abstract
Farnesoid X receptor (FXR, NR1H4) is a ligand-activated nuclear receptor, which regulates bile acid, lipid and glucose metabolism. Due to these functions, FXR has been investigated as a potential drug target for the treatment of liver diseases, such as primary biliary cholangitis and non-alcoholic steatohepatitis. Based on the previously described four splice variants, it has been suggested that alternative promoter usage and splicing may have an impact on total FXR activity as a result of encoding functionally diverse variants. Here we aimed for a systematic analysis of human hepatic FXR splice variants. In addition to the previously described FXRα1-4, we identified four novel splice variants (FXRα5-8) in human hepatocytes, which resulted from previously undetected exon skipping events. These newly identified isoforms displayed diminished DNA binding and impaired transactivation activities. Isoform FXRα5, which suppressed the transactivation activity of the functional isoform FXRα2, was further characterized as deficient in heterodimerization, coactivator recruitment and ligand binding. These findings were further supported by molecular dynamics simulations, which offered an explanation for the behavior of this isoform on the molecular level. FXRα5 exhibited low uniform expression levels in nearly all human tissues. Our systematic analysis of FXR splice variants in human hepatocytes resulted in the identification of four novel FXR isoforms, which all proved to be functionally deficient, but one novel variant, FXRα5, also displayed dominant negative activity. The possible associations with and roles of these novel isoforms in human liver diseases require further investigation.
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Affiliation(s)
- Enni-Kaisa Mustonen
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart and University of Tübingen, Tübingen, Germany
| | - Serene M L Lee
- Biobank of the Department of General, Visceral and Transplantation Surgery, University Hospital LMU Munich, Munich, Germany
| | - Hanno Nieß
- Biobank of the Department of General, Visceral and Transplantation Surgery, University Hospital LMU Munich, Munich, Germany
| | - Matthias Schwab
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart and University of Tübingen, Tübingen, Germany; Departments of Clinical Pharmacology, and Pharmacy and Biochemistry, University of Tübingen, Tübingen, Germany
| | - Tatu Pantsar
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmaceutical Sciences, University of Tübingen, Tübingen, Germany; School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
| | - Oliver Burk
- Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Stuttgart and University of Tübingen, Tübingen, Germany.
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12
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Farnesoid X receptor (FXR): Structures and ligands. Comput Struct Biotechnol J 2021; 19:2148-2159. [PMID: 33995909 PMCID: PMC8091178 DOI: 10.1016/j.csbj.2021.04.029] [Citation(s) in RCA: 88] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 04/10/2021] [Accepted: 04/10/2021] [Indexed: 02/07/2023] Open
Abstract
Farnesoid X receptor (FXR) is a bile acid activated nuclear receptor (BAR) and is mainly expressed in the liver and intestine. Upon ligand binding, FXR regulates key genes involved in the metabolic process of bile acid synthesis, transport and reabsorption and is also involved in the metabolism of carbohydrates and lipids. Because of its important functions, FXR is considered as a promising drug target for the therapy of bile acid-related liver diseases. With the approval of obeticholic acid (OCA) as the first small molecule to target FXR, many other small molecules are being evaluated in clinical trials. This review summarizes the structures of FXR, especially its ligand binding domain, and the development of small molecules (including agonists and antagonists) targeting FXR.
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13
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Thibaut R, Gage MC, Pineda-Torra I, Chabrier G, Venteclef N, Alzaid F. Liver macrophages and inflammation in physiology and physiopathology of non-alcoholic fatty liver disease. FEBS J 2021; 289:3024-3057. [PMID: 33860630 PMCID: PMC9290065 DOI: 10.1111/febs.15877] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 03/05/2021] [Accepted: 04/12/2021] [Indexed: 12/13/2022]
Abstract
Non‐alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome, being a common comorbidity of type 2 diabetes and with important links to inflammation and insulin resistance. NAFLD represents a spectrum of liver conditions ranging from steatosis in the form of ectopic lipid storage, to inflammation and fibrosis in nonalcoholic steatohepatitis (NASH). Macrophages that populate the liver play important roles in maintaining liver homeostasis under normal physiology and in promoting inflammation and mediating fibrosis in the progression of NAFLD toward to NASH. Liver macrophages are a heterogenous group of innate immune cells, originating from the yolk sac or from circulating monocytes, that are required to maintain immune tolerance while being exposed portal and pancreatic blood flow rich in nutrients and hormones. Yet, liver macrophages retain a limited capacity to raise the alarm in response to danger signals. We now know that macrophages in the liver play both inflammatory and noninflammatory roles throughout the progression of NAFLD. Macrophage responses are mediated first at the level of cell surface receptors that integrate environmental stimuli, signals are transduced through multiple levels of regulation in the cell, and specific transcriptional programmes dictate effector functions. These effector functions play paramount roles in determining the course of disease in NAFLD and even more so in the progression towards NASH. The current review covers recent reports in the physiological and pathophysiological roles of liver macrophages in NAFLD. We emphasise the responses of liver macrophages to insulin resistance and the transcriptional machinery that dictates liver macrophage function.
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Affiliation(s)
- Ronan Thibaut
- Cordeliers Research Centre, INSERM, IMMEDIAB Laboratory, Sorbonne Université, Université de Paris, France
| | - Matthew C Gage
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - Inès Pineda-Torra
- Department of Medicine, Centre for Cardiometabolic and Vascular Science, University College London, UK
| | - Gwladys Chabrier
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - Nicolas Venteclef
- Cordeliers Research Centre, INSERM, IMMEDIAB Laboratory, Sorbonne Université, Université de Paris, France
| | - Fawaz Alzaid
- Cordeliers Research Centre, INSERM, IMMEDIAB Laboratory, Sorbonne Université, Université de Paris, France
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14
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Preidis GA, Soni KG, Suh JH, Halder T, Kim KH, Choi JM, Li F, Devaraj S, Conner ME, Coarfa C, Jung SY, Moore DD. Coagulopathy in Malnourished Mice Is Sexually Dimorphic and Regulated by Nutrient-Sensing Nuclear Receptors. Hepatol Commun 2020; 4:1835-1850. [PMID: 33305154 PMCID: PMC7706303 DOI: 10.1002/hep4.1622] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/28/2020] [Accepted: 09/18/2020] [Indexed: 11/23/2022] Open
Abstract
Liver dysfunction, including coagulopathy, is a prominent feature of protein-energy malnutrition. To identify mechanisms underlying malnutrition-associated coagulopathy, we administered a low-protein low-fat diet to lactating dams and examined hepatic transcription and plasma coagulation parameters in young adult weanlings. Malnutrition impacted body composition to a greater extent in male versus female mice. Transcriptional profiles suggested opposing effects of nutrient-sensing nuclear receptors, namely induction of peroxisome proliferator-activated receptor α (PPARα) targets and repression of farnesoid-X-receptor (FXR) targets. Coagulopathy with decreased synthesis of fibrinogen-α (FGA) and factor 11 (F11) was observed in malnourished male animals but not female animals. In primary mouse hepatocytes, FXR agonist increased and PPARα agonist decreased Fga and F11 messenger RNA expression. Nuclear receptor DNA response elements were identified in the Fga and F11 gene regulatory regions, and opposing effects of FXR and PPARα were confirmed with luciferase assays. Unexpectedly, hepatic PPARα protein was markedly depleted in malnourished male liver and was not enriched on Fga or F11 response elements. Rather, there was loss of FXR binding at these response elements. Reduced PPARα protein was associated with loss of hepatocyte peroxisomes, which are necessary for bile acid biosynthesis, and with decreased concentrations of bile acids that function as FXR ligands, most notably the FXR agonist chenodeoxycholic acid. Conclusion: Malnutrition impairs growth and liver synthetic function more severely in male mice than in female mice. Malnourished male mice are coagulopathic and exhibit decreased hepatocyte peroxisomes, FXR agonist bile acids, FXR binding on Fga and F11 gene regulatory elements, and coagulation factor synthesis. These effects are absent in female mice, which have low baseline levels of PPARα, suggesting that nutrient-sensing nuclear receptors regulate coagulation factor synthesis in response to host nutritional status in a sex-specific manner.
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Affiliation(s)
- Geoffrey A. Preidis
- Section of Gastroenterology, Hepatology & NutritionDepartment of PediatricsBaylor College of Medicine and Texas Children’s HospitalHoustonTXUSA
| | - Krishnakant G. Soni
- Section of Gastroenterology, Hepatology & NutritionDepartment of PediatricsBaylor College of Medicine and Texas Children’s HospitalHoustonTXUSA
| | - Ji Ho Suh
- Section of Gastroenterology, Hepatology & NutritionDepartment of PediatricsBaylor College of Medicine and Texas Children’s HospitalHoustonTXUSA
| | - Tripti Halder
- Section of Gastroenterology, Hepatology & NutritionDepartment of PediatricsBaylor College of Medicine and Texas Children’s HospitalHoustonTXUSA
| | - Kang Ho Kim
- Department of Molecular and Cellular BiologyBaylor College of MedicineHoustonTXUSA
| | - Jong Min Choi
- Advanced Technology CoreMass Spectrometry Proteomics CoreBaylor College of MedicineHoustonTXUSA
| | - Feng Li
- Department of Molecular and Cellular BiologyBaylor College of MedicineHoustonTXUSA
- Department of Pathology and ImmunologyBaylor College of MedicineHoustonTXUSA
| | - Sridevi Devaraj
- Department of Pathology and ImmunologyBaylor College of MedicineHoustonTXUSA
| | - Margaret E. Conner
- Department of Molecular Virology and MicrobiologyBaylor College of MedicineHoustonTXUSA
| | - Cristian Coarfa
- Department of Molecular and Cellular BiologyBaylor College of MedicineHoustonTXUSA
| | - Sung Yun Jung
- Department of Molecular and Cellular BiologyBaylor College of MedicineHoustonTXUSA
- Advanced Technology CoreMass Spectrometry Proteomics CoreBaylor College of MedicineHoustonTXUSA
- Verna and Marrs McLean Department of Biochemistry and Molecular BiologyBaylor College of MedicineHoustonTXUSA
| | - David D. Moore
- Department of Molecular and Cellular BiologyBaylor College of MedicineHoustonTXUSA
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15
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Ramos Pittol JM, Milona A, Morris I, Willemsen ECL, van der Veen SW, Kalkhoven E, van Mil SWC. FXR Isoforms Control Different Metabolic Functions in Liver Cells via Binding to Specific DNA Motifs. Gastroenterology 2020; 159:1853-1865.e10. [PMID: 32712104 DOI: 10.1053/j.gastro.2020.07.036] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 07/14/2020] [Accepted: 07/21/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND & AIMS The nuclear receptor subfamily 1 group H member 4 (NR1H4, also called FXR) is a ligand-activated transcription factor that, upon binding of bile acids, regulates the expression of genes involved in bile acid, fat, sugar, and amino acid metabolism. Transcript variants encode the FXR isoforms alpha 1, alpha 2, alpha 3, and alpha 4, which activate different genes that regulate metabolism. Little is known about the mechanisms by which the different isoforms regulate specific genes or how the expression of these genes affects the outcomes of patients given drugs that target FXR. METHODS We determined genome-wide binding of FXR isoforms in mouse liver organoids that express individual FXR isoforms using chromatin immunoprecipitation, followed by sequencing analysis and DNA motif discovery. We validated regulatory DNA sequences by mobility shift assays and with luciferase reporters using mouse and human FXR isoforms. We analyzed mouse liver organoids and HepG2 cells that expressed the FXR isoforms using chromatin immunoprecipitation, quantitative polymerase chain reaction, and immunoblot assays. Organoids were analyzed for mitochondrial respiration, lipid droplet content, and triglyceride excretion. We used the FXR ligand obeticholic acid to induce FXR activity in organoids, cell lines, and mice. We collected data on the binding of FXR in mouse liver and the expression levels of FXR isoforms and gene targets in human liver tissue and primary human hepatocytes from the Gene Expression Omnibus. RESULTS In mouse liver cells, 89% of sites that bound FXR were bound by only FXRα2 or FXRα4, via direct interactions with the DNA sequence motif ER-2. Via DNA binding, these isoforms regulated metabolic functions in liver cells, including carbon metabolism and lipogenesis. Incubation with obeticholic acid increased mitochondrial pyruvate transport and reduced insulin-induced lipogenesis in organoids that expressed FXRα2 but not FXRα1. In human liver tissues, levels of FXRα2 varied significantly and correlated with expression of genes predicted to be regulated via an ER-2 motif. CONCLUSIONS Most metabolic effects regulated by FXR in mouse and human liver cells are regulated by the FXRα2 isoform via specific binding to ER-2 motifs. The expression level of FXRα2 in liver might be used to predict responses of patients to treatment with FXR agonists.
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Affiliation(s)
- Jose Miguel Ramos Pittol
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands; Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Alexandra Milona
- Medical Research Council, London Institute of Medical Sciences, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Imogen Morris
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Ellen C L Willemsen
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Suzanne W van der Veen
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Eric Kalkhoven
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Saskia W C van Mil
- Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands.
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16
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Stofan M, Guo GL. Bile Acids and FXR: Novel Targets for Liver Diseases. Front Med (Lausanne) 2020; 7:544. [PMID: 33015098 PMCID: PMC7516013 DOI: 10.3389/fmed.2020.00544] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 07/30/2020] [Indexed: 12/12/2022] Open
Abstract
Bile acids (BAs) are evolutionally conserved molecules synthesized in the liver from cholesterol and have been shown to be essential for lipid homeostasis. BAs regulate a variety of metabolic functions via modulating nuclear and membrane receptors. Farnesoid X receptor (FXR) is the most important nuclear receptor for maintaining BA homeostasis. FXR plays a tissue-specific role in suppressing BA synthesis and promoting BA enterohepatic circulation. Disruption of FXR in mice have been implicated in liver diseases commonly occurring in humans, including cholestasis, non-alcoholic fatty liver diseases, and hepatocellular carcinoma. Strategically targeting FXR activity has been rapidly used to develop novel therapies for the prevention and/or treatment of cholestasis and non-alcoholic steatohepatitis. This review provides an updated literature review on BA homeostasis and FXR modulator development.
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Affiliation(s)
- Mary Stofan
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, United States
| | - Grace L Guo
- Department of Pharmacology and Toxicology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, United States.,Environmental and Occupational Health Sciences Institute, Rutgers, The State University of New Jersey, Piscataway, NJ, United States.,VA New Jersey Health Care System, Veterans Administration Medical Center, East Orange, NJ, United States
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17
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Enhanced alcoholic liver disease in mice with intestine-specific farnesoid X receptor deficiency. J Transl Med 2020; 100:1158-1168. [PMID: 32404932 PMCID: PMC8487140 DOI: 10.1038/s41374-020-0439-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 04/27/2020] [Accepted: 04/27/2020] [Indexed: 12/13/2022] Open
Abstract
Alcoholic fatty liver disease (AFLD) is one of the major causes of liver morbidity and mortality worldwide. We have previously shown that whole-body, but not hepatocyte-specific, deficiency of farnesoid X receptor (FXR) in mice worsens AFLD, suggesting that extrahepatic FXR deficiency is critical for AFLD development. Intestinal FXR is critical in suppressing hepatic bile acid (BA) synthesis by inducing fibroblast growth factor 15 (FGF15) in mice and FGF19 in humans. We hypothesized that intestinal FXR is critical for reducing AFLD development in mice. To test this hypothesis, we compared the AFLD severity in wild type (WT) and intestine-specific Fxr knockout (FXRInt-/-) mice following treatment with control or ethanol-containing diet. We found that FXRInt-/- mice were more susceptible to ethanol-induced liver steatosis and inflammation, compared with WT mice. Ethanol treatment altered the expression of hepatic genes involved in lipid and BA homeostasis, and ethanol detoxification. Gut FXR deficiency increased intestinal permeability, likely due to reduced mucosal integrity, as revealed by decreased secretion of Mucin 2 protein and lower levels of E-cadherin protein. In summary, intestinal FXR may protect AFLD development by maintaining gut integrity.
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18
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Gai Z, Gui T, Alecu I, Lone MA, Hornemann T, Chen Q, Visentin M, Hiller C, Hausler S, Kullak-Ublick GA. Farnesoid X receptor activation induces the degradation of hepatotoxic 1-deoxysphingolipids in non-alcoholic fatty liver disease. Liver Int 2020; 40:844-859. [PMID: 31883408 DOI: 10.1111/liv.14340] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 12/17/2019] [Accepted: 12/23/2019] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS Patients with non-alcoholic fatty liver disease (NAFLD) exhibit higher levels of plasma 1-deoxysphingolipids than healthy individuals. The aim of this study was to investigate the role of farnesoid X receptor (FXR) in 1-deoxysphingolipid de novo synthesis and degradation. METHODS Mice were fed with a high-fat diet (HFD) to induce obesity and NAFLD, and then treated with the FXR ligand obeticholic acid (OCA). Histology and gene expression analysis were performed on liver tissue. Sphingolipid patterns from NAFLD patients and mouse models were assessed by liquid chromatography-mass spectrometry. The molecular mechanism underlying the effect of FXR activation on sphingolipid metabolism was studied in Huh7 cells and primary cultured hepatocytes, as well as in a 1-deoxysphinganine-treated mouse model. RESULTS 1-deoxysphingolipids were increased in both NAFLD patients and mouse models. FXR activation by OCA protected the liver against oxidative stress, apoptosis, and reduced 1-deoxysphingolipid levels, both in a HFD-induced mouse model of obesity and in 1-deoxysphinganine-treated mice. In vitro, FXR activation lowered intracellular 1-deoxysphingolipid levels by inducing Cyp4f-mediated degradation, but not by inhibiting de novo synthesis, thereby protecting hepatocytes against doxSA-induced cytotoxicity, mitochondrial damage, and apoptosis. Overexpression of Cyp4f13 in cells was sufficient to ameliorate doxSA-induced cytotoxicity. Treatment with the Cyp4f pan-inhibitor HET0016 or FXR knock-down fully abolished the protective effect of OCA, indicating that OCA-mediated 1-deoxysphingolipid degradation is FXR and Cyp4f dependent. CONCLUSIONS Our study identifies FXR-Cyp4f as a novel regulatory pathway for 1-deoxysphingolipid metabolism. FXR activation represents a promising therapeutic strategy for patients with metabolic syndrome and NAFLD.
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Affiliation(s)
- Zhibo Gai
- Key Laboratory of Traditional Chinese Medicine for Classical Theory, Ministry of Education, Shandong University of Traditional Chinese Medicine, Jinan, China.,Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Ting Gui
- Key Laboratory of Traditional Chinese Medicine for Classical Theory, Ministry of Education, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Irina Alecu
- Neural Regeneration Laboratory, Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, uOttawa Brain and Mind Research Institute, Ottawa, ON, Canada.,Department of Chemistry and Biomolecular Sciences, Centre for Catalysis and Research Innovation, University of Ottawa, Ottawa, ON, Canada
| | - Museer A Lone
- Department of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Thorsten Hornemann
- Department of Clinical Chemistry, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Qingfa Chen
- The Institute for Tissue Engineering and Regenerative Medicine, The Liaocheng University/Liaocheng People's Hospital, Liaocheng, China
| | - Michele Visentin
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Christian Hiller
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Stephanie Hausler
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Gerd A Kullak-Ublick
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.,Mechanistic Safety, CMO & Patient Safety, Global Drug Development, Novartis Pharma, Basel, Switzerland
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19
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Wang B, Zhang H, Luan Z, Xu H, Wei Y, Zhao X, Xing M, Huo X, Zhang J, Su W, Guan Y, Zhang X. Farnesoid X receptor (FXR) activation induces the antioxidant protein metallothionein 1 expression in mouse liver. Exp Cell Res 2020; 390:111949. [PMID: 32145254 DOI: 10.1016/j.yexcr.2020.111949] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 03/03/2020] [Accepted: 03/04/2020] [Indexed: 12/12/2022]
Abstract
Farnesoid X receptor (FXR) is a metabolic nuclear receptor, which protects liver from many endogenous and exogenous injuries. Metallothioneins (MTs) belong to a low-molecular-weight protein family involved in metal homeostasis and the regulation of hepatic oxidative stress. In the present study, we aimed to investigate the effect of FXR on hepatic MT1 expression and the underlying mechanism. C57BL/6 mice or primary cultured mouse hepatocytes were treated with the synthetic FXR ligand GW4064 or natural ligand CDCA. RNA-Sequencing (RNA-seq) analysis was performed to identify gene expression profile in the livers of mice treated with GW4064. Real-time PCR and Western blot were applied to determine the expression of MT1 and other FXR target genes in the livers of mice and primary hepatocytes treated with GW4064 and CDCA. Cellular and subcellular locations of MT1 in the livers of mice treated with GW4064 were examined using immunohistochemistry assay. FXR small interfering RNAs (siRNA) was transfected to silence FXR. Luciferase reporter and chromatin immunoprecipitation (ChIP) assays were utilized to confirm the regulation of MT1 gene promoter activity by FXR. RNA-seq analysis revealed that GW4064 treatment significantly induced MT1 expression in mouse liver. Consistently, MT1 expression in the hepatocytes of mouse livers and cultured hepatocytes was upregulated by GW4064 as well as CDCA. In addition, adenovirus-mediated overexpression of FXR markedly increased, while siRNA-mediated FXR silencing significantly suppressed MT1 expression in cultured hepatocytes. Luciferase reporter and ChIP assays further confirmed that the MT1 gene was under the direct control of FXR. Collectively, our findings demonstrate that MT1 is a novel target gene of FXR and may contribute to antioxidative capacity of FXR in liver diseases.
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Affiliation(s)
- Bing Wang
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China; Department of Endocrinology, Dalian Municipal Central Hospital, Dalian Medical University, Dalian, Liaoning, 116033, China
| | - Haibo Zhang
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Zhilin Luan
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China; Department of Physiology and Pathology, School of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China; Dalian Key Laboratory for Nuclear Receptors in Major Metabolic Diseases, Dalian, Liaoning, 116044, China
| | - Hu Xu
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China; Dalian Key Laboratory for Nuclear Receptors in Major Metabolic Diseases, Dalian, Liaoning, 116044, China
| | - Yuanyi Wei
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Xuejia Zhao
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Miaomiao Xing
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Xiaoxiao Huo
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Jiayang Zhang
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China
| | - Wen Su
- Department of Pathology, Shenzhen University Health Science Center, Shenzhen, 518060, China
| | - Youfei Guan
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China; Department of Physiology and Pathology, School of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China; Dalian Key Laboratory for Nuclear Receptors in Major Metabolic Diseases, Dalian, Liaoning, 116044, China.
| | - Xiaoyan Zhang
- Advanced Institute for Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China; Department of Physiology and Pathology, School of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning, 116044, China; Dalian Key Laboratory for Nuclear Receptors in Major Metabolic Diseases, Dalian, Liaoning, 116044, China.
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20
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Farnesoid X receptor and bile acids regulate vitamin A storage. Sci Rep 2019; 9:19493. [PMID: 31862954 PMCID: PMC6925179 DOI: 10.1038/s41598-019-55988-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 11/29/2019] [Indexed: 12/18/2022] Open
Abstract
The nuclear receptor Farnesoid X Receptor (FXR) is activated by bile acids and controls multiple metabolic processes, including bile acid, lipid, carbohydrate, amino acid and energy metabolism. Vitamin A is needed for proper metabolic and immune control and requires bile acids for efficient intestinal absorption and storage in the liver. Here, we analyzed whether FXR regulates vitamin A metabolism. Compared to control animals, FXR-null mice showed strongly reduced (>90%) hepatic levels of retinol and retinyl palmitate and a significant reduction in lecithin retinol acyltransferase (LRAT), the enzyme responsible for hepatic vitamin A storage. Hepatic reintroduction of FXR in FXR-null mice induced vitamin A storage in the liver. Hepatic vitamin A levels were normal in intestine-specific FXR-null mice. Obeticholic acid (OCA, 3 weeks) treatment rapidly reduced (>60%) hepatic retinyl palmitate levels in mice, concurrent with strongly increased retinol levels (>5-fold). Similar, but milder effects were observed in cholic acid (12 weeks)-treated mice. OCA did not change hepatic LRAT protein levels, but strongly reduced all enzymes involved in hepatic retinyl ester hydrolysis, involving mostly post-transcriptional mechanisms. In conclusion, vitamin A metabolism in the mouse liver heavily depends on the FXR and FXR-targeted therapies may be prone to cause vitamin A-related pathologies.
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21
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Penvose A, Keenan JL, Bray D, Ramlall V, Siggers T. Comprehensive study of nuclear receptor DNA binding provides a revised framework for understanding receptor specificity. Nat Commun 2019; 10:2514. [PMID: 31175293 PMCID: PMC6555819 DOI: 10.1038/s41467-019-10264-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 05/02/2019] [Indexed: 01/06/2023] Open
Abstract
The type II nuclear receptors (NRs) function as heterodimeric transcription factors with the retinoid X receptor (RXR) to regulate diverse biological processes in response to endogenous ligands and therapeutic drugs. DNA-binding specificity has been proposed as a primary mechanism for NR gene regulatory specificity. Here we use protein-binding microarrays (PBMs) to comprehensively analyze the DNA binding of 12 NR:RXRα dimers. We find more promiscuous NR-DNA binding than has been reported, challenging the view that NR binding specificity is defined by half-site spacing. We show that NRs bind DNA using two distinct modes, explaining widespread NR binding to half-sites in vivo. Finally, we show that the current models of NR specificity better reflect binding-site activity rather than binding-site affinity. Our rich dataset and revised NR binding models provide a framework for understanding NR regulatory specificity and will facilitate more accurate analyses of genomic datasets. The type II nuclear receptors (NRs) and the retinoid X receptor (RXR) form heterodimeric transcription factors to regulate development, metabolism, and inflammation. Here the authors employ protein-binding microarrays to comprehensively analyze the DNA binding of 12 NR:RXRα heterodimers, and report promiscuous NR-DNA binding.
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Affiliation(s)
- Ashley Penvose
- Department of Biology, Boston University, Boston, MA, 02215, USA.,Biological Design Center, Boston University, Boston, MA, 02215, USA
| | - Jessica L Keenan
- Biological Design Center, Boston University, Boston, MA, 02215, USA.,Bioinformatics Program, Boston University, Boston, MA, 02215, USA
| | - David Bray
- Biological Design Center, Boston University, Boston, MA, 02215, USA.,Bioinformatics Program, Boston University, Boston, MA, 02215, USA
| | - Vijendra Ramlall
- Department of Biology, Boston University, Boston, MA, 02215, USA.,Biological Design Center, Boston University, Boston, MA, 02215, USA
| | - Trevor Siggers
- Department of Biology, Boston University, Boston, MA, 02215, USA. .,Biological Design Center, Boston University, Boston, MA, 02215, USA. .,Bioinformatics Program, Boston University, Boston, MA, 02215, USA.
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22
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Dong B, Singh AB, Guo GL, Young M, Liu J. Activation of FXR by obeticholic acid induces hepatic gene expression of SR-BI through a novel mechanism of transcriptional synergy with the nuclear receptor LXR. Int J Mol Med 2019; 43:1927-1938. [PMID: 30896855 PMCID: PMC6443341 DOI: 10.3892/ijmm.2019.4136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 02/13/2019] [Indexed: 11/06/2022] Open
Abstract
The farnesoid X receptor (FXR) is known to regulate the gene expression of SR‑BI, which mediates plasma high‑density lipoprotein (HDL)‑cholesterol uptake. Our previous study demonstrated that the activation of FXR by obeticholic acid (OCA) lowered plasma HDL‑cholesterol levels and increased the hepatic mRNA and protein expression levels of SR‑BI in hypercholesterolemic hamsters, but not in normolipidemic hamsters, suggesting that dietary cholesterol may be involved in the OCA‑induced transcription of SR‑BI. In the present study, a functional 90‑base‑pair regulatory region was identified in the first intron of the SR‑BI gene of hamster and mouse that contains a FXR response element (IR‑1) and an adjacent liver X receptor (LXR) response element (LXRE). By in vitro DNA binding and luciferase reporter gene assays, it was demonstrated that FXR and LXR bind to their recognition sequences within this intronic region and transactivate the SR‑BI reporter gene in a synergistic manner. It was also shown that mutations at either the IR‑1 site or the LXRE site eliminated OCA‑mediated gene transcription. Utilizing chow‑fed hamsters as an in vivo model, it was demonstrated that treating normolipidemic hamsters with OCA or GW3965 alone did not effectively induce levels of SR‑BI, whereas their combined treatment significantly increased the mRNA and protein levels of SR‑BI in the liver. The study further investigated effects of FXR and LXR coactivation on the gene expression of SR‑BI in human liver cells. The intronic FXRE and LXRE regulatory region was not conserved in the human SR‑BI genomic sequence, however, higher mRNA expression levels of SR‑BI were observed in human primary hepatocytes and HepG2 cells exposed to combined treatments of FXR and LXR agonists, compared with those in cells exposed to individual ligand treatment. Therefore, these results suggest that human SR‑BI gene transcription may also be subject to concerted activation by FXR and LXR, mediated via currently unidentified regulatory sequences.
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Affiliation(s)
- Bin Dong
- Department of Veterans Affairs, Palo Alto Health Care System, Palo Alto, CA 94304, USA
| | - Amar B Singh
- Department of Veterans Affairs, Palo Alto Health Care System, Palo Alto, CA 94304, USA
| | - Grace L Guo
- Department of Pharmacology and Toxicology, School of Pharmacy, Rutgers University, Piscataway, NJ 08854, USA
| | - Mark Young
- Mistral Therapeutics, San Diego, CA 92121, USA
| | - Jingwen Liu
- Department of Veterans Affairs, Palo Alto Health Care System, Palo Alto, CA 94304, USA
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23
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Abstract
Genetic cholestasis has been dissected through genetic investigation. The major PFIC genes are now described. ATP8B1 encodes FIC1, ABCB11 encodes BSEP, ABCB4 encodes MDR3, TJP2 encodes TJP2, NR1H4 encodes FXR, and MYO5B encodes MYO5B. The full spectra of phenotypes associated with mutations in each gene are discussed, along with our understanding of the disease mechanisms. Differences in treatment response and targets for future treatment are emerging.
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Affiliation(s)
- Laura N Bull
- Department of Medicine and Institute for Human Genetics, University of California San Francisco, UCSF Liver Center Laboratory, Zuckerberg San Francisco General, 1001 Potrero Avenue, Building 40, Room 4102, San Francisco, CA 94110, USA.
| | - Richard J Thompson
- Institute of Liver Studies, King's College London, King's College Hospital, Denmark Hill, London SE5 9RS, UK
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24
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Tian J, Marino R, Johnson C, Locker J. Binding of Drug-Activated CAR/Nr1i3 Alters Metabolic Regulation in the Liver. iScience 2018; 9:209-228. [PMID: 30396153 PMCID: PMC6222290 DOI: 10.1016/j.isci.2018.10.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 08/02/2018] [Accepted: 10/16/2018] [Indexed: 12/12/2022] Open
Abstract
The constitutive androstane receptor (CAR/Nr1i3) regulates detoxification of drugs and other xenobiotics by the liver. Binding of these compounds, activating ligands, causes CAR to translocate to the nucleus and stimulate genes of detoxification. However, CAR activation also changes metabolism and induces rapid liver growth. To explain this gene regulation, we characterized the genome-wide early binding of CAR; its binding partner, RXRα; and the acetylation that they induced on H4K5. CAR-linked genes showed either stimulation or inhibition and regulated lipid, carbohydrate, and energy metabolism, as well as detoxification. Stimulation of expression increased, but inhibition did not decrease, H4K5Ac. Transcriptional inhibition occurred when CAR bound with HNF4α, PPARα, or FXR on the same enhancers. Functional competition among these bound nuclear receptors normally coordinates transcriptional resources as metabolism shifts. However, binding of drug-activated CAR to the same enhancers adds a new competitor that constitutively alters the normal balance of metabolic gene regulation. CAR activation stimulates a massive liver transcriptional response Target genes control drug detoxification, general metabolism, and liver growth CAR stimulates genes through coactivation and histone acetylation CAR inhibits genes when it shares their enhancers with other nuclear receptors
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Affiliation(s)
- Jianmin Tian
- Department of Pathology, School of Medicine, University of Pittsburgh, 200 Lothrop St, Pittsburgh, PA 15261, USA
| | - Rebecca Marino
- Department of Pathology, School of Medicine, University of Pittsburgh, 200 Lothrop St, Pittsburgh, PA 15261, USA
| | - Carla Johnson
- Department of Pathology, School of Medicine, University of Pittsburgh, 200 Lothrop St, Pittsburgh, PA 15261, USA
| | - Joseph Locker
- Department of Pathology, School of Medicine, University of Pittsburgh, 200 Lothrop St, Pittsburgh, PA 15261, USA.
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25
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Mayo MJ, Wigg AJ, Leggett BA, Arnold H, Thompson AJ, Weltman M, Carey EJ, Muir AJ, Ling L, Rossi SJ, DePaoli AM. NGM282 for Treatment of Patients With Primary Biliary Cholangitis: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial. Hepatol Commun 2018; 2:1037-1050. [PMID: 30202819 PMCID: PMC6128239 DOI: 10.1002/hep4.1209] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/16/2018] [Indexed: 01/07/2023] Open
Abstract
Patients with primary biliary cholangitis (PBC) who had an inadequate response to ursodiol have few treatment options. Alkaline phosphatase (ALP) and bilirubin levels correlate with the risk of liver transplant or death in PBC patients. Fibroblast growth factor (FGF) 19 is a hormone that acts directly in the liver to regulate bile acid synthesis. We evaluated NGM282, an engineered analogue of FGF19, for the treatment of PBC. In this 28-day, double-blind, placebo-controlled phase 2 trial, 45 PBC patients who had an inadequate response to ursodiol were randomly assigned 1:1:1 to receive subcutaneous daily doses of either NGM282 at 0.3 mg (n = 14), 3 mg (n = 16), or placebo (n = 15). The primary endpoint was a change in ALP from baseline after 28 days of treatment. At day 28, ALP was significantly reduced with NGM282 treatment at both 0.3 mg (least-squares mean -51.0 IU/L [standard error (SE) 15.4]) and 3 mg (-66.0 IU/L [SE 16.0]) versus placebo (3.3 IU/L [SE 14.8]), with least-squares mean differences of -54.3 IU/L (95% confidence interval -104.2 to -4.5; P = 0.0149) and -69.3 IU/L (95% confidence interval -120.5 to -18.3; P = 0.0030), respectively. Fifty percent (7 of 14) of patients receiving NGM282 0.3 mg and 46% (6 of 13) of those receiving NGM282 3mg achieved 15% or greater reduction in ALP levels from baseline, compared with 7% (1 of 15) of patients receiving placebo. NGM282 also significantly reduced serum concentrations of transaminases and immunoglobulins. Most adverse events were grade 1 (mild) to grade 2 (moderate) in severity, with gastrointestinal disorders more frequent in the NGM282 treatment groups. No worsening of pruritus was observed with NGM282 treatment. Conclusion: NGM282 administered for 28 days resulted in significant improvements in ALP and transaminase levels compared with placebo, with an acceptable safety profile in patients with PBC. (Hepatology Communications 2018; 00:000-000).
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Affiliation(s)
- Marlyn J Mayo
- University of Texas Southwestern Medical Center Dallas Texas
| | - Alan J Wigg
- Flinders Medical Center Adelaide South Australia Australia
| | - Barbara A Leggett
- Royal Brisbane and Women's Hospital and School of Medicine University of Queensland Brisbane Queensland Australia
| | | | | | | | | | | | - Lei Ling
- NGM Biopharmaceuticals Inc. South San Francisco California
| | | | - Alex M DePaoli
- NGM Biopharmaceuticals Inc. South San Francisco California
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26
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Liu X, Guo GL, Kong B, Hilburn DB, Hubchak SC, Park S, LeCuyer B, Hsieh A, Wang L, Fang D, Green RM. Farnesoid X receptor signaling activates the hepatic X-box binding protein 1 pathway in vitro and in mice. Hepatology 2018; 68:304-316. [PMID: 29377207 PMCID: PMC6033648 DOI: 10.1002/hep.29815] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 12/20/2017] [Accepted: 01/16/2018] [Indexed: 12/19/2022]
Abstract
UNLABELLED Bile acids are endogenous ligands of the nuclear receptor, farnesoid X receptor (FXR), and pharmacological FXR modulators are under development for the treatment of several liver disorders. The inositol-requiring enzyme 1α/X-box binding protein 1 (IRE1α/XBP1) pathway of the unfolded protein response (UPR) is a protective cellular signaling pathway activated in response to endoplasmic reticulum (ER) stress. We investigated the role of FXR signaling in activation of the hepatic XBP1 pathway. Mice were treated with deoxycholic acid (DCA), cholestyramine, GW4064, or underwent bile duct ligation (BDL), and hepatic UPR activation was measured. Huh7-Ntcp and HepG2 cells were treated with FXR agonists, inhibitor, small interfering RNA (siRNA), or small heterodimer partner (SHP) siRNA to determine the mechanisms of IRE1α/XBP1 pathway activation. DCA feeding and BDL increased and cholestyramine decreased expression of hepatic XBP1 spliced (XBP1s). XBP1 pathway activation increased in Huh7-Ntcp and HepG2 cells treated with bile acids, 6α-ethyl-chenodeoxycholic acid (6-ECDCA) or GW4064. This effect decreased with FXR knockdown and treatment with the FXR inhibitor guggulsterone. FXR agonists increased XBP1 splicing and phosphorylated IRE1α (p-IRE1α) expression. Overexpression of SHP similarly increased XBP1 splicing, XBP1s, and p-IRE1α protein expression. SHP knockdown attenuated FXR agonist-induced XBP1s and p-IRE1α protein expression. Co-immunoprecipitation (Co-IP) assays demonstrate a physical interaction between overexpressed green fluorescent protein (GFP)-SHP and FLAG-IRE1α in HEK293T cells. Mice treated with GW4064 had increased, and FXR and SHP null mice had decreased, basal Xbp1s gene expression. CONCLUSION FXR signaling activates the IRE1α/XBP1 pathway in vivo and in vitro. FXR pathway activation increases XBP1 splicing and enhances p-IRE1α expression. These effects are mediated, at least in part, by SHP. IRE1α/XBP1 pathway activation by bile acids and pharmacological FXR agonists may be protective during liver injury and may have therapeutic implications for liver diseases. (Hepatology 2018;68:304-316).
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Affiliation(s)
- Xiaoying Liu
- Division of Gastroenterology and Hepatology, Department of Medicine, Chicago, IL
| | - Grace L. Guo
- Department of Pharmacology and Toxicology, School of Pharmacy, Rutgers University, Piscataway, NJ
| | - Bo Kong
- Department of Pharmacology and Toxicology, School of Pharmacy, Rutgers University, Piscataway, NJ
| | - David B. Hilburn
- Division of Gastroenterology and Hepatology, Department of Medicine, Chicago, IL
| | - Susan C. Hubchak
- Division of Gastroenterology and Hepatology, Department of Medicine, Chicago, IL
| | - Seong Park
- Division of Gastroenterology and Hepatology, Department of Medicine, Chicago, IL
| | - Brian LeCuyer
- Division of Gastroenterology and Hepatology, Department of Medicine, Chicago, IL
| | - Antony Hsieh
- Division of Gastroenterology and Hepatology, Department of Medicine, Chicago, IL
| | - Li Wang
- Department of Physiology and Neurobiology, and the Institute for Systems Genomics, University of Connecticut, Storrs, CT,Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, CT,Veterans Affairs Connecticut Healthcare System, West Haven, CT
| | - Deyu Fang
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Richard M. Green
- Division of Gastroenterology and Hepatology, Department of Medicine, Chicago, IL
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27
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A rare missense variant in NR1H4 associates with lower cholesterol levels. Commun Biol 2018; 1:14. [PMID: 30271901 PMCID: PMC6123719 DOI: 10.1038/s42003-018-0015-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 01/11/2018] [Indexed: 12/12/2022] Open
Abstract
Searching for novel sequence variants associated with cholesterol levels is of particular interest due to the causative role of non-HDL cholesterol levels in cardiovascular disease. Through whole-genome sequencing of 15,220 Icelanders and imputation of the variants identified, we discovered a rare missense variant in NR1H4 (R436H) associating with lower levels of total cholesterol (effect = −0.47 standard deviations or −0.55 mmol L−1, p = 4.21 × 10−10, N = 150,211). Importantly, NR1H4 R436H also associates with lower levels of non-HDL cholesterol and, consistent with this, protects against coronary artery disease. NR1H4 encodes FXR that regulates bile acid homeostasis, however, we do not detect a significant association between R436H and biological markers of liver function. Transcriptional profiling of hepatocytes carrying R436H shows that it is not a loss-of-function variant. Rather, we observe changes in gene expression compatible with effects on lipids. These findings highlight the role of FXR in regulation of cholesterol levels in humans. Aimee Deaton et al. identify a rare missense variant in the bile acid receptor gene NR1H4, which is associated with lower levels of total cholesterol in the Icelandic population. Hepatocytes expressing the missense variant showed altered expression of a small number of genes, with enrichment in lipid-related pathways.
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28
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Jena PK, Sheng L, Di Lucente J, Jin LW, Maezawa I, Wan YJY. Dysregulated bile acid synthesis and dysbiosis are implicated in Western diet-induced systemic inflammation, microglial activation, and reduced neuroplasticity. FASEB J 2018; 32:2866-2877. [PMID: 29401580 DOI: 10.1096/fj.201700984rr] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The goal of this study was to identify the intrinsic links that explain the effect of a Western diet (WD) on cognitive dysfunction. Specific pathogen-free, wild-type mice were fed either a control diet (CD) or a high-fat, high-sucrose WD after weaning and were euthanized at 10 mo of age to study the pathways that affect cognitive health. The results showed that long-term WD intake reduced hippocampal synaptic plasticity and the level of brain-derived neurotrophic factor mRNA in the brain and isolated microglia. A WD also activated ERK1/2 and reduced postsynaptic density-95 in the brain, suggesting postsynaptic damage. Moreover, WD-fed mice had increased inflammatory signaling in the brain, ileum, liver, adipose tissue, and spleen, which was accompanied by microglia activation. In the brain, as well as in the digestive tract, a WD reduced signaling regulated by retinoic acid and bile acids (BAs), whose receptors form heterodimers to control metabolism and inflammation. Furthermore, a WD intake caused dysbiosis and dysregulated BA synthesis with reduced endogenous ligands for BA receptors, i.e., farnesoid X receptor and G-protein-coupled bile acid receptor in the liver and brain. Together, dysregulated BA synthesis and dysbiosis were accompanied by systemic inflammation, microglial activation, and reduced neuroplasticity induced by WD.-Jena, P. K., Sheng, L., Di Lucente, J., Jin, L.-W., Maezawa, I., Wan, Y.-J. Y. Dysregulated bile acid synthesis and dysbiosis are implicated in Western diet-induced systemic inflammation, microglial activation, and reduced neuroplasticity.
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Affiliation(s)
- Prasant Kumar Jena
- Department of Medical Pathology and Laboratory Medicine University of California, Davis, Sacramento, California, USA; and
| | - Lili Sheng
- Department of Medical Pathology and Laboratory Medicine University of California, Davis, Sacramento, California, USA; and
| | - Jacopo Di Lucente
- Department of Medical Pathology and Laboratory Medicine University of California, Davis, Sacramento, California, USA; and.,Medical Investigation of Neurodevelopmental Disorders Institute, University of California, Davis, Sacramento, California, USA
| | - Lee-Way Jin
- Department of Medical Pathology and Laboratory Medicine University of California, Davis, Sacramento, California, USA; and.,Medical Investigation of Neurodevelopmental Disorders Institute, University of California, Davis, Sacramento, California, USA
| | - Izumi Maezawa
- Department of Medical Pathology and Laboratory Medicine University of California, Davis, Sacramento, California, USA; and.,Medical Investigation of Neurodevelopmental Disorders Institute, University of California, Davis, Sacramento, California, USA
| | - Yu-Jui Yvonne Wan
- Department of Medical Pathology and Laboratory Medicine University of California, Davis, Sacramento, California, USA; and
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29
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Cassano M, Offner S, Planet E, Piersigilli A, Jang SM, Henry H, Geuking MB, Mooser C, McCoy KD, Macpherson AJ, Trono D. Polyphenic trait promotes liver cancer in a model of epigenetic instability in mice. Hepatology 2017; 66:235-251. [PMID: 28370258 PMCID: PMC5518198 DOI: 10.1002/hep.29182] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 03/10/2017] [Accepted: 03/23/2017] [Indexed: 12/23/2022]
Abstract
UNLABELLED Hepatocellular carcinoma (HCC) represents the fifth-most common form of cancer worldwide and carries a high mortality rate attributed to lack of effective treatment. Males are 8 times more likely to develop HCC than females, an effect largely driven by sex hormones, albeit through still poorly understood mechanisms. We previously identified TRIM28 (tripartite protein 28), a scaffold protein capable of recruiting a number of chromatin modifiers, as a crucial mediator of sexual dimorphism in the liver. Trim28hep-/- mice display sex-specific transcriptional deregulation of a wide range of bile and steroid metabolism genes and development of liver adenomas in males. We now demonstrate that obesity and aging precipitate alterations of TRIM28-dependent transcriptional dynamics, leading to a metabolic infection state responsible for highly penetrant male-restricted hepatic carcinogenesis. Molecular analyses implicate aberrant androgen receptor stimulation, biliary acid disturbances, and altered responses to gut microbiota in the pathogenesis of Trim28hep-/- -associated HCC. Correspondingly, androgen deprivation markedly attenuates the frequency and severity of tumors, and raising animals under axenic conditions completely abrogates their abnormal phenotype, even upon high-fat diet challenge. CONCLUSION This work underpins how discrete polyphenic traits in epigenetically metastable conditions can contribute to a cancer-prone state and more broadly provides new evidence linking hormonal imbalances, metabolic disturbances, gut microbiota, and cancer. (Hepatology 2017;66:235-251).
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Affiliation(s)
- Marco Cassano
- School of Life SciencesEcole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
| | - Sandra Offner
- School of Life SciencesEcole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
| | - Evarist Planet
- School of Life SciencesEcole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
| | - Alessandra Piersigilli
- School of Life SciencesEcole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland,Institute of Animal Pathology, Vetsuisse FacultyUniversity of BernBernSwitzerland
| | - Suk Min Jang
- School of Life SciencesEcole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
| | - Hugues Henry
- Clinical Chemistry Laboratory, Lausanne University Hospital, Faculty of Biology and MedicineUniversity of LausanneLausanneSwitzerland
| | - Markus B. Geuking
- Mucosal Immunology Lab, Department of Clinical ResearchUniversity of BernBernSwitzerland
| | - Catherine Mooser
- Mucosal Immunology Lab, Department of Clinical ResearchUniversity of BernBernSwitzerland
| | - Kathy D. McCoy
- Mucosal Immunology Lab, Department of Clinical ResearchUniversity of BernBernSwitzerland
| | - Andrew J. Macpherson
- Mucosal Immunology Lab, Department of Clinical ResearchUniversity of BernBernSwitzerland
| | - Didier Trono
- School of Life SciencesEcole Polytechnique Fédérale de Lausanne (EPFL)LausanneSwitzerland
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30
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Aboudehen K, Noureddine L, Cobo-Stark P, Avdulov S, Farahani S, Gearhart MD, Bichet DG, Pontoglio M, Patel V, Igarashi P. Hepatocyte Nuclear Factor-1 β Regulates Urinary Concentration and Response to Hypertonicity. J Am Soc Nephrol 2017; 28:2887-2900. [PMID: 28507058 DOI: 10.1681/asn.2016101095] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 04/16/2017] [Indexed: 12/18/2022] Open
Abstract
The transcription factor hepatocyte nuclear factor-1β (HNF-1β) is essential for normal kidney development and function. Inactivation of HNF-1β in mouse kidney tubules leads to early-onset cyst formation and postnatal lethality. Here, we used Pkhd1/Cre mice to delete HNF-1β specifically in renal collecting ducts (CDs). CD-specific HNF-1β mutant mice survived long term and developed slowly progressive cystic kidney disease, renal fibrosis, and hydronephrosis. Compared with wild-type littermates, HNF-1β mutant mice exhibited polyuria and polydipsia. Before the development of significant renal structural abnormalities, mutant mice exhibited low urine osmolality at baseline and after water restriction and administration of desmopressin. However, mutant and wild-type mice had similar plasma vasopressin and solute excretion levels. HNF-1β mutant kidneys showed increased expression of aquaporin-2 mRNA but mislocalized expression of aquaporin-2 protein in the cytoplasm of CD cells. Mutant kidneys also had decreased expression of the UT-A urea transporter and collectrin, which is involved in apical membrane vesicle trafficking. Treatment of HNF-1β mutant mIMCD3 cells with hypertonic NaCl inhibited the induction of osmoregulated genes, including Nr1h4, which encodes the transcription factor FXR that is required for maximal urinary concentration. Chromatin immunoprecipitation and sequencing experiments revealed HNF-1β binding to the Nr1h4 promoter in wild-type kidneys, and immunoblot analysis revealed downregulated expression of FXR in HNF-1β mutant kidneys. These findings reveal a novel role of HNF-1β in osmoregulation and identify multiple mechanisms, whereby mutations of HNF-1β produce defects in urinary concentration.
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Affiliation(s)
- Karam Aboudehen
- Departments of Medicine and.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Lama Noureddine
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Patricia Cobo-Stark
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | | | | | - Micah D Gearhart
- Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota
| | - Daniel G Bichet
- Departments of Medicine and.,Molecular and Integrative Physiology, Université de Montréal, Montreal, Quebec, Canada; and
| | - Marco Pontoglio
- Department of Development, Reproduction and Cancer, Institut Cochin, Institut National de la Santé et de la Recherche Médicale U1016/Centre National de la Recherche Scientifique Unité Mixte de Recherche 8104, Université Paris-Descartes, Paris, France
| | - Vishal Patel
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Peter Igarashi
- Departments of Medicine and .,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
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31
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A sequential EMT-MET mechanism drives the differentiation of human embryonic stem cells towards hepatocytes. Nat Commun 2017; 8:15166. [PMID: 28466868 PMCID: PMC5418622 DOI: 10.1038/ncomms15166] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 03/03/2017] [Indexed: 12/30/2022] Open
Abstract
Reprogramming has been shown to involve EMT–MET; however, its role in cell differentiation is unclear. We report here that in vitro differentiation of hESCs to hepatic lineage undergoes a sequential EMT–MET with an obligatory intermediate mesenchymal phase. Gene expression analysis reveals that Activin A-induced formation of definitive endoderm (DE) accompanies a synchronous EMT mediated by autocrine TGFβ signalling followed by a MET process. Pharmacological inhibition of TGFβ signalling blocks the EMT as well as DE formation. We then identify SNAI1 as the key EMT transcriptional factor required for the specification of DE. Genetic ablation of SNAI1 in hESCs does not affect the maintenance of pluripotency or neural differentiation, but completely disrupts the formation of DE. These results reveal a critical mesenchymal phase during the acquisition of DE, highlighting a role for sequential EMT–METs in both differentiation and reprogramming. Reprogramming has been shown to involve EMT-MET; however, its role in cell differentiation is unclear. Here the authors show that during in vitro differentiation of hepatocytes, Activin A-induced formation of definitive endoderm requires EMT mediated by TGFβ signalling, followed by a MET process.
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32
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Lu D, Wang S, Xie Q, Guo L, Wu B. Transcriptional Regulation of Human UDP-Glucuronosyltransferase 2B10 by Farnesoid X Receptor in Human Hepatoma HepG2 Cells. Mol Pharm 2017; 14:2899-2907. [PMID: 28267333 DOI: 10.1021/acs.molpharmaceut.6b01103] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Little is known about transcriptional regulators of UDP-glucuronosyltransferase 2B10 (UGT2B10), an enzyme known to glucuronidate many chemicals and drugs such as nicotine and tricyclic antidepressants. Here, we uncovered that UGT2B10 was transcriptionally regulated by farnesoid X receptor (FXR), the bile acid sensing nuclear receptor. GW4064 and chenodeoxycholic acid (two specific FXR agonists) treatment of HepG2 cells led to a significant increase in the mRNA level of UGT2B10. The treated cells also showed enhanced glucuronidation activities toward amitriptyline (an UGT2B10 probe substrate). In reporter gene assays, the extent of UGT2B10 activation by the FXR agonists was positively correlated with the amount of cotransfected FXR. Consistently, knockdown of FXR by shRNA attenuated the induction effect on UGT2B10 expression. Furthermore, a combination of electrophoretic mobility shift assay and chromatin immunoprecipitation showed that the FXR receptor trans-activated UGT2B10 through its specific binding to the -209- to -197-bp region (an IR1 element) of the UGT2B10 promoter. In summary, our results for the first time established FXR as a transcriptional regulator of human UGT2B10.
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Affiliation(s)
- Danyi Lu
- Division of Pharmaceutics, College of Pharmacy, Jinan University , 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Shuai Wang
- Division of Pharmaceutics, College of Pharmacy, Jinan University , 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Qian Xie
- Division of Pharmaceutics, College of Pharmacy, Jinan University , 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Lianxia Guo
- Division of Pharmaceutics, College of Pharmacy, Jinan University , 601 Huangpu Avenue West, Guangzhou 510632, China
| | - Baojian Wu
- Division of Pharmaceutics, College of Pharmacy, Jinan University , 601 Huangpu Avenue West, Guangzhou 510632, China
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Preidis GA, Kim KH, Moore DD. Nutrient-sensing nuclear receptors PPARα and FXR control liver energy balance. J Clin Invest 2017; 127:1193-1201. [PMID: 28287408 DOI: 10.1172/jci88893] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The nuclear receptors PPARα (encoded by NR1C1) and farnesoid X receptor (FXR, encoded by NR1H4) are activated in the liver in the fasted and fed state, respectively. PPARα activation induces fatty acid oxidation, while FXR controls bile acid homeostasis, but both nuclear receptors also regulate numerous other metabolic pathways relevant to liver energy balance. Here we review evidence that they function coordinately to control key nutrient pathways, including fatty acid oxidation and gluconeogenesis in the fasted state and lipogenesis and glycolysis in the fed state. We have also recently reported that these receptors have mutually antagonistic impacts on autophagy, which is induced by PPARα but suppressed by FXR. Secretion of multiple blood proteins is a major drain on liver energy and nutrient resources, and we present preliminary evidence that the liver secretome may be directly suppressed by PPARα, but induced by FXR. Finally, previous studies demonstrated a striking deficiency in bile acid levels in malnourished mice that is consistent with results in malnourished children. We present evidence that hepatic targets of PPARα and FXR are dysregulated in chronic undernutrition. We conclude that PPARα and FXR function coordinately to integrate liver energy balance.
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Abstract
PURPOSE OF REVIEW About 15-25% of patients with simple steatosis of non-alcoholic fatty liver disease progresses to non-alcoholic steatohepatitis (NASH), and the underlying mechanism for this progression has not been elucidated. NASH ultimately could progress to cirrhosis, an irreversible condition. RECENT FINDINGS Farnesoid X receptor (FXR) has been studied for its role in modulating inflammation, and the expression of FXR is down-regulated during NASH development. FXR deficiency has shown to progress and exacerbate NASH development, and FXR activation has been protective against liver inflammation associated with NASH. The expression of factors in both the adaptive and innate immune response in the liver are regulated in a FXR-dependent and -independent manner. SUMMARY Therefore, understanding key signaling pathways of liver inflammation in NASH is important to determine essential components that predispose, progress, or exacerbate NASH. FXR has been identified as a therapeutic target for NASH to prevent liver inflammation.
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Saeed A, Hoekstra M, Hoeke MO, Heegsma J, Faber KN. The interrelationship between bile acid and vitamin A homeostasis. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:496-512. [PMID: 28111285 DOI: 10.1016/j.bbalip.2017.01.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 01/04/2017] [Accepted: 01/18/2017] [Indexed: 12/12/2022]
Abstract
Vitamin A is a fat-soluble vitamin important for vision, reproduction, embryonic development, cell differentiation, epithelial barrier function and adequate immune responses. Efficient absorption of dietary vitamin A depends on the fat-solubilizing properties of bile acids. Bile acids are synthesized in the liver and maintained in an enterohepatic circulation. The liver is also the main storage site for vitamin A in the mammalian body, where an intimate collaboration between hepatocytes and hepatic stellate cells leads to the accumulation of retinyl esters in large cytoplasmic lipid droplet hepatic stellate cells. Chronic liver diseases are often characterized by disturbed bile acid and vitamin A homeostasis, where bile production is impaired and hepatic stellate cells lose their vitamin A in a transdifferentiation process to myofibroblasts, cells that produce excessive extracellular matrix proteins leading to fibrosis. Chronic liver diseases thus may lead to vitamin A deficiency. Recent data reveal an intricate crosstalk between vitamin A metabolites and bile acids, in part via the Retinoic Acid Receptor (RAR), Retinoid X Receptor (RXR) and the Farnesoid X Receptor (FXR), in maintaining vitamin A and bile acid homeostasis. Here, we provide an overview of the various levels of "communication" between vitamin A metabolites and bile acids and its relevance for the treatment of chronic liver diseases.
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Affiliation(s)
- Ali Saeed
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Institute of Molecular biology & Bio-technology, Bahauddin Zakariya University, Multan, Pakistan.
| | - Mark Hoekstra
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
| | - Martijn Oscar Hoeke
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
| | - Janette Heegsma
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Laboratory Medicine, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
| | - Klaas Nico Faber
- Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
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Dong B, Young M, Liu X, Singh AB, Liu J. Regulation of lipid metabolism by obeticholic acid in hyperlipidemic hamsters. J Lipid Res 2016; 58:350-363. [PMID: 27940481 DOI: 10.1194/jlr.m070888] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 11/28/2016] [Indexed: 12/21/2022] Open
Abstract
The farnesoid X receptor (FXR) plays critical roles in plasma cholesterol metabolism, in particular HDL-cholesterol (HDL-C) homeostasis. Obeticholic acid (OCA) is a FXR agonist being developed for treating various chronic liver diseases. Previous studies reported inconsistent effects of OCA on regulating plasma cholesterol levels in different animal models and in different patient populations. The mechanisms underlying its divergent effects have not yet been thoroughly investigated. The scavenger receptor class B type I (SR-BI) is a FXR-modulated gene and the major receptor for HDL-C. We investigated the effects of OCA on hepatic SR-BI expression and correlated such effects with plasma HDL-C levels and hepatic cholesterol efflux in hyperlipidemic hamsters. We demonstrated that OCA induced a time-dependent reduction in serum HDL-C levels after 14 days of treatment, which was accompanied by a significant reduction of liver cholesterol content and increases in fecal cholesterol in OCA-treated hamsters. Importantly, hepatic SR-BI mRNA and protein levels in hamsters were increased to 1.9- and 1.8-fold of control by OCA treatment. Further investigations in normolipidemic hamsters did not reveal OCA-induced changes in serum HDL-C levels or hepatic SR-BI expression. We conclude that OCA reduces plasma HDL-C levels and promotes transhepatic cholesterol efflux in hyperlipidemic hamsters via a mechanism involving upregulation of hepatic SR-BI.
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Affiliation(s)
- Bin Dong
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304
| | - Mark Young
- Intercept Pharmaceuticals, Inc., San Diego, CA 92121
| | - Xueqing Liu
- Intercept Pharmaceuticals, Inc., San Diego, CA 92121
| | | | - Jingwen Liu
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304
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Pharmacotoxicology of clinically-relevant concentrations of obeticholic acid in an organotypic human hepatocyte system. Toxicol In Vitro 2016; 39:93-103. [PMID: 27939613 DOI: 10.1016/j.tiv.2016.11.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/23/2016] [Accepted: 11/29/2016] [Indexed: 01/11/2023]
Abstract
Nonalcoholic steatohepatitis (NASH) is an emerging health crisis with no approved therapies. Obeticholic acid (OCA), a farnesoid X receptor (FXR) agonist, shows promise in NASH trials. However, the precise mechanisms mediating OCA effects and impact on cholesterol metabolism are not fully understood. We explored the pharmaco-toxicological effects of OCA on patho-physiological pathways in hepatocytes using a previously described perfused organotypic liver system that allows culture in near-physiological insulin/glucose milieus, and exhibits drug responses at clinically-relevant concentrations. Primary hepatocytes experienced 48-hour exposure to OCA at concentrations approximating therapeutic (0.5μM) and supratherapeutic (10μM) levels. Global transcriptomics by RNAseq was complimented by cellular viability (MTT), CYP activity assays, and secreted FGF19 levels in the media. Dose-dependent, transcriptional effects suggested suppression of bile acid synthesis (↓CYP7A1, ↓CYP27A1) and increased bile efflux (↑ABCB4, ↑ABCB11, ↑OSTA, ↑OSTB). Pleiotropic effects included suppression of TGFβ and IL-6 signaling pathways, and signatures suggestive of HDL suppression (↑SCARB1, ↓ApoAI, ↓LCAT) and LDL elevation (↑ApoB, ↓CYP7A1). OCA exhibited direct FXR-mediated effects with increased FGF19 secretion. Transcriptomics revealed regulation of metabolic, anti-inflammatory, and anti-fibrotic pathways beneficial in NASH, and predicted cholesterol profiles consistent with clinical findings. Follow-up studies under lipotoxic/inflammatory conditions would corroborate these effects in a disease-relevant environment.
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Zhu Y, Liu H, Zhang M, Guo GL. Fatty liver diseases, bile acids, and FXR. Acta Pharm Sin B 2016; 6:409-412. [PMID: 27709009 PMCID: PMC5045552 DOI: 10.1016/j.apsb.2016.07.008] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 05/11/2016] [Accepted: 05/27/2016] [Indexed: 02/09/2023] Open
Abstract
The prevalence of nonalcoholic fatty liver disease (NAFLD) worldwide has increased at an alarming rate, which will likely result in enormous medical and economic burden. NAFLD presents as a spectrum of liver diseases ranging from simple steatosis, nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and even to hepatocellular carcinoma (HCC). A comprehensive understanding of the mechanism(s) of NAFLD-to-NASH transition remains elusive with various genetic and environmental susceptibility factors possibly involved. An understanding of the mechanism may provide novel strategies in the prevention and treatment to NASH. Abnormal regulation of bile acid homeostasis emerges as an important mechanism to liver injury. The bile acid homeostasis is critically regulated by the farnesoid X receptor (FXR) that is activated by bile acids. FXR has been known to exert tissue-specific effects in regulating bile acid synthesis and transport. Current investigations demonstrate FXR also plays a principle role in regulating lipid metabolism and suppressing inflammation in the liver. Therefore, the future determination of the molecular mechanism by which FXR protects the liver from developing NAFLD may shed light to the prevention and treatment of NAFLD.
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Ivanov M, Kals M, Lauschke V, Barragan I, Ewels P, Käller M, Axelsson T, Lehtiö J, Milani L, Ingelman-Sundberg M. Single base resolution analysis of 5-hydroxymethylcytosine in 188 human genes: implications for hepatic gene expression. Nucleic Acids Res 2016; 44:6756-69. [PMID: 27131363 PMCID: PMC5001587 DOI: 10.1093/nar/gkw316] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 04/13/2016] [Indexed: 01/31/2023] Open
Abstract
To improve the epigenomic analysis of tissues rich in 5-hydroxymethylcytosine (hmC), we developed a novel protocol called TAB-Methyl-SEQ, which allows for single base resolution profiling of both hmC and 5-methylcytosine by targeted next-generation sequencing. TAB-Methyl-SEQ data were extensively validated by a set of five methodologically different protocols. Importantly, these extensive cross-comparisons revealed that protocols based on Tet1-assisted bisulfite conversion provided more precise hmC values than TrueMethyl-based methods. A total of 109 454 CpG sites were analyzed by TAB-Methyl-SEQ for mC and hmC in 188 genes from 20 different adult human livers. We describe three types of variability of hepatic hmC profiles: (i) sample-specific variability at 40.8% of CpG sites analyzed, where the local hmC values correlate to the global hmC content of livers (measured by LC-MS), (ii) gene-specific variability, where hmC levels in the coding regions positively correlate to expression of the respective gene and (iii) site-specific variability, where prominent hmC peaks span only 1 to 3 neighboring CpG sites. Our data suggest that both the gene- and site-specific components of hmC variability might contribute to the epigenetic control of hepatic genes. The protocol described here should be useful for targeted DNA analysis in a variety of applications.
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Affiliation(s)
- Maxim Ivanov
- Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, Nanna Svartz väg 2, 17177 Stockholm, Sweden
| | - Mart Kals
- Estonian Genome Center, University of Tartu, Riia 23b, 51010 Tartu, Estonia Institute of Mathematics and Statistics, University of Tartu, J. Liivi 2, 50409 Tartu, Estonia
| | - Volker Lauschke
- Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, Nanna Svartz väg 2, 17177 Stockholm, Sweden
| | - Isabel Barragan
- Group of Pharmacoepigenetics, Department of Physiology and Pharmacology, Karolinska Institutet, Von Eulers väg 8 IV, 17177 Stockholm, Sweden
| | - Philip Ewels
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, 10691 Stockholm, Sweden
| | - Max Käller
- Science for Life Laboratory, School of Biotechnology, Division of Gene Technology, Royal Institute of Technology, 17121 Stockholm, Sweden
| | - Tomas Axelsson
- Department of Medical Sciences, Molecular Medicine and Science for Life Laboratory, Uppsala University, 75144 Uppsala, Sweden
| | - Janne Lehtiö
- Science for Life Laboratory, Cancer Proteomics Mass Spectrometry, Department of Oncology-Pathology, Karolinska Institutet, 17121 Stockholm, Sweden
| | - Lili Milani
- Estonian Genome Center, University of Tartu, Riia 23b, 51010 Tartu, Estonia
| | - Magnus Ingelman-Sundberg
- Section of Pharmacogenetics, Department of Physiology and Pharmacology, Karolinska Institutet, Nanna Svartz väg 2, 17177 Stockholm, Sweden
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Mutations in the nuclear bile acid receptor FXR cause progressive familial intrahepatic cholestasis. Nat Commun 2016; 7:10713. [PMID: 26888176 PMCID: PMC4759630 DOI: 10.1038/ncomms10713] [Citation(s) in RCA: 187] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 01/11/2016] [Indexed: 02/07/2023] Open
Abstract
Neonatal cholestasis is a potentially life-threatening condition requiring prompt diagnosis. Mutations in several different genes can cause progressive familial intrahepatic cholestasis, but known genes cannot account for all familial cases. Here we report four individuals from two unrelated families with neonatal cholestasis and mutations in NR1H4, which encodes the farnesoid X receptor (FXR), a bile acid-activated nuclear hormone receptor that regulates bile acid metabolism. Clinical features of severe, persistent NR1H4-related cholestasis include neonatal onset with rapid progression to end-stage liver disease, vitamin K-independent coagulopathy, low-to-normal serum gamma-glutamyl transferase activity, elevated serum alpha-fetoprotein and undetectable liver bile salt export pump (ABCB11) expression. Our findings demonstrate a pivotal function for FXR in bile acid homeostasis and liver protection. Neonatal cholestasis is a result of elevated bile acid levels, and is associated with mutations in genes regulating bile acid homeostasis. Here the authors identify mutations in the bile acid sensing farnesoid X receptor in four individuals with neonatal cholestasis from two unrelated families.
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41
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Gai Z, Gui T, Hiller C, Kullak-Ublick GA. Farnesoid X Receptor Protects against Kidney Injury in Uninephrectomized Obese Mice. J Biol Chem 2015; 291:2397-411. [PMID: 26655953 DOI: 10.1074/jbc.m115.694323] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Indexed: 01/07/2023] Open
Abstract
Activation of the farnesoid X receptor (FXR) has indicated a therapeutic potential for this nuclear bile acid receptor in the prevention of diabetic nephropathy and obesity-induced renal damage. Here, we investigated the protective role of FXR against kidney damage induced by obesity in mice that had undergone uninephrectomy, a model resembling the clinical situation of kidney donation by obese individuals. Mice fed a high-fat diet developed the core features of metabolic syndrome, with subsequent renal lipid accumulation and renal injury, including glomerulosclerosis, interstitial fibrosis, and albuminuria. The effects were accentuated by uninephrectomy. In human renal biopsies, staining of 4-hydroxynonenal (4-HNE), glucose-regulated protein 78 (Grp78), and C/EBP-homologous protein, markers of endoplasmic reticulum stress, was more prominent in the proximal tubules of 15 obese patients compared with 16 non-obese patients. In mice treated with the FXR agonist obeticholic acid, renal injury, renal lipid accumulation, apoptosis, and changes in lipid peroxidation were attenuated. Moreover, disturbed mitochondrial function was ameliorated and the mitochondrial respiratory chain recovered following obeticholic acid treatment. Culturing renal proximal tubular cells with free fatty acid and FXR agonists showed that FXR activation protected cells from free fatty acid-induced oxidative stress and endoplasmic reticulum stress, as denoted by a reduction in the level of reactive oxygen species staining and Grp78 immunostaining, respectively. Several genes involved in glutathione metabolism were induced by FXR activation in the remnant kidney, which was consistent with a decreased glutathione disulfide/glutathione ratio. In summary, FXR activation maintains endogenous glutathione homeostasis and protects the kidney in uninephrectomized mice from obesity-induced injury.
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Affiliation(s)
- Zhibo Gai
- From the Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, CH-8091 Zurich, Switzerland and
| | - Ting Gui
- the Department of Nephrology, Hypertension, and Clinical Pharmacology, Inselspital, CH-3010 Bern, Switzerland
| | - Christian Hiller
- From the Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, CH-8091 Zurich, Switzerland and
| | - Gerd A Kullak-Ublick
- From the Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, CH-8091 Zurich, Switzerland and
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42
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Mazuy C, Helleboid A, Staels B, Lefebvre P. Nuclear bile acid signaling through the farnesoid X receptor. Cell Mol Life Sci 2015; 72:1631-50. [PMID: 25511198 PMCID: PMC11113650 DOI: 10.1007/s00018-014-1805-y] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/04/2014] [Accepted: 12/08/2014] [Indexed: 12/16/2022]
Abstract
Bile acids (BAs) are amphipathic molecules produced from cholesterol by the liver. Expelled from the gallbladder upon meal ingestion, BAs serve as fat solubilizers in the intestine. BAs are reabsorbed in the ileum and return via the portal vein to the liver where, together with nutrients, they provide signals to coordinate metabolic responses. BAs act on energy and metabolic homeostasis through the activation of membrane and nuclear receptors, among which the nuclear receptor farnesoid X receptor (FXR) is an important regulator of several metabolic pathways. Highly expressed in the liver and the small intestine, FXR contributes to BA effects on metabolism, inflammation and cell cycle control. The pharmacological modulation of its activity has emerged as a potential therapeutic strategy for liver and metabolic diseases. This review highlights recent advances regarding the mechanisms by which the BA sensor FXR contributes to global signaling effects of BAs, and how FXR activity may be regulated by nutrient-sensitive signaling pathways.
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Affiliation(s)
- Claire Mazuy
- European Genomic Institute for Diabetes (EGID), 59000 Lille, France
- INSERM UMR1011-Bâtiment J&K, 59000 Lille, France
- University Lille 2, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
| | - Audrey Helleboid
- European Genomic Institute for Diabetes (EGID), 59000 Lille, France
- INSERM UMR1011-Bâtiment J&K, 59000 Lille, France
- University Lille 2, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
| | - Bart Staels
- European Genomic Institute for Diabetes (EGID), 59000 Lille, France
- INSERM UMR1011-Bâtiment J&K, 59000 Lille, France
- University Lille 2, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
| | - Philippe Lefebvre
- European Genomic Institute for Diabetes (EGID), 59000 Lille, France
- INSERM UMR1011-Bâtiment J&K, 59000 Lille, France
- University Lille 2, 59000 Lille, France
- Institut Pasteur de Lille, 59019 Lille, France
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Ouma WZ, Mejia-Guerra MK, Yilmaz A, Pareja-Tobes P, Li W, Doseff AI, Grotewold E. Important biological information uncovered in previously unaligned reads from chromatin immunoprecipitation experiments (ChIP-Seq). Sci Rep 2015; 5:8635. [PMID: 25727450 PMCID: PMC4345404 DOI: 10.1038/srep08635] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Accepted: 01/12/2015] [Indexed: 12/04/2022] Open
Abstract
Establishing the architecture of gene regulatory networks (GRNs) relies on chromatin immunoprecipitation followed by massively parallel sequencing (ChIP-Seq) methods that provide genome-wide transcription factor binding sites (TFBSs). ChIP-Seq furnishes millions of short reads that, after alignment, describe the genome-wide binding sites of a particular TF. However, in all organisms investigated an average of 40% of reads fail to align to the corresponding genome, with some datasets having as much as 80% of reads failing to align. We describe here the provenance of previously unaligned reads in ChIP-Seq experiments from animals and plants. We show that a substantial portion corresponds to sequences of bacterial and metazoan origin, irrespective of the ChIP-Seq chromatin source. Unforeseen was the finding that 30%–40% of unaligned reads were actually alignable. To validate these observations, we investigated the characteristics of the previously unaligned reads corresponding to TAL1, a human TF involved in lineage specification of hemopoietic cells. We show that, while unmapped ChIP-Seq read datasets contain foreign DNA sequences, additional TFBSs can be identified from the previously unaligned ChIP-Seq reads. Our results indicate that the re-evaluation of previously unaligned reads from ChIP-Seq experiments will significantly contribute to TF target identification and determination of emerging properties of GRNs.
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Affiliation(s)
- Wilberforce Zachary Ouma
- 1] Molecular, Cellular and Developmental Biology (MCDB) Graduate Program, The Ohio State University, Columbus, OH, USA [2] Center for Applied Plant Sciences (CAPS), The Ohio State University, Columbus, OH, USA
| | - Maria Katherine Mejia-Guerra
- 1] Molecular, Cellular and Developmental Biology (MCDB) Graduate Program, The Ohio State University, Columbus, OH, USA [2] Center for Applied Plant Sciences (CAPS), The Ohio State University, Columbus, OH, USA
| | - Alper Yilmaz
- Department of Bioengineering, Yildiz Technical University, Istanbul, Turkey
| | - Pablo Pareja-Tobes
- Oh no sequences! Research group, Era7 Information Technologies SLU, Granada, Spain
| | - Wei Li
- 1] Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA [2] Department Physiology and Cell Biology, Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Andrea I Doseff
- 1] Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA [2] Department Physiology and Cell Biology, Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Erich Grotewold
- 1] Center for Applied Plant Sciences (CAPS), The Ohio State University, Columbus, OH, USA [2] Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA
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Ding L, Yang L, Wang Z, Huang W. Bile acid nuclear receptor FXR and digestive system diseases. Acta Pharm Sin B 2015; 5:135-44. [PMID: 26579439 PMCID: PMC4629217 DOI: 10.1016/j.apsb.2015.01.004] [Citation(s) in RCA: 242] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 12/31/2014] [Accepted: 01/05/2015] [Indexed: 12/14/2022] Open
Abstract
Bile acids (BAs) are not only digestive surfactants but also important cell signaling molecules, which stimulate several signaling pathways to regulate some important biological processes. The bile-acid-activated nuclear receptor, farnesoid X receptor (FXR), plays a pivotal role in regulating bile acid, lipid and glucose homeostasis as well as in regulating the inflammatory responses, barrier function and prevention of bacterial translocation in the intestinal tract. As expected, FXR is involved in the pathophysiology of a wide range of diseases of gastrointestinal tract, including inflammatory bowel disease, colorectal cancer and type 2 diabetes. In this review, we discuss current knowledge of the roles of FXR in physiology of the digestive system and the related diseases. Better understanding of the roles of FXR in digestive system will accelerate the development of FXR ligands/modulators for the treatment of digestive system diseases.
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Key Words
- 6-ECDCA, 6α-ethyl-chenodeoxycholic acid
- AF2, activation domain
- ANGTPL3, angiopoietin-like protein 3
- AOM, azoxymethane
- AP-1, activator protein-1
- ASBT, apical sodium-dependent bile salt transporter
- Apo, apolipoprotein
- BAAT, bile acid-CoA amino acid N-acetyltransferase
- BACS, bile acid-CoA synthetase
- BAs, bile acids
- BMI, body mass index
- BSEP, bile salt export pump
- Bile acids
- CA, cholic acid
- CD, Crohn׳s disease
- CDCA, chenodeoxycholic acid
- CREB, cAMP regulatory element-binding protein
- CYP7A1, cholesterol 7α-hydroxylase
- Colorectal cancer
- DBD, DNA binding domain
- DCA, deoxycholic acid
- DSS, dextrane sodium sulfate
- ERK, extracellular signal-regulated kinase
- FABP6, fatty acid-binding protein subclass 6
- FFAs, free fatty acids
- FGF19, fibroblast growth factor 19
- FGFR4, fibroblast growth factor receptor 4
- FXR, farnesoid X receptor
- FXRE, farnesoid X receptor response element
- Farnesoid X receptor
- G6Pase, glucose-6-phosphatase
- GLP-1, glucagon-like peptide 1
- GLUT2, glucose transporter type 2
- GPBAR, G protein-coupled BA receptor
- GPCRs, G protein-coupled receptors
- GSK3, glycogen synthase kinase 3
- Gastrointestinal tract
- HDL-C, high density lipoprotein cholesterol
- HNF4α, hepatic nuclear factor 4α
- I-BABP, intestinal bile acid-binding protein
- IBD, inflammatory bowel disease
- IL-1, interleukin 1
- Inflammatory bowel disease
- KLF11, Krüppel-like factor 11
- KRAS, Kirsten rat sarcoma viral oncogene homolog
- LBD, ligand binding domain
- LCA, lithocholic acid
- LPL, lipoprotein lipase
- LRH-1, liver receptor homolog-1
- MCA, muricholicacid
- MRP2, multidrug resistance-associated protein 2
- NF-κB, nuclear factor-kappa B
- NOD, non-obese diabetic
- NRs, nuclear receptors
- OSTα, organic solute transporter alpha
- OSTβ, organic solute transporter beta
- PEPCK, phosphoenol pyruvate carboxykinase
- PGC-1α, peroxisome proliferators-activated receptor γ coactivator protein-1α
- SHP, small heterodimer partner
- SREBP-1c, sterol regulatory element-binding protein 1c
- STAT3, signal transducers and activators of transcription 3
- T2D, type 2 diabetes
- TLCA, taurolithocholic acid
- TNBS, trinitrobenzensulfonic acid
- TNFα, tumor necrosis factors α
- Type 2 diabetes
- UC, ulcerative colitis
- UDCA, ursodeoxycholic acid
- VSG, vertical sleeve gastrectomy
- db/db, diabetic mice
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Koutsounas I, Theocharis S, Delladetsima I, Patsouris E, Giaginis C. Farnesoid x receptor in human metabolism and disease: the interplay between gene polymorphisms, clinical phenotypes and disease susceptibility. Expert Opin Drug Metab Toxicol 2015; 11:523-32. [PMID: 25553772 DOI: 10.1517/17425255.2014.999664] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Farnesoid x receptor (FXR) belongs to the group of nuclear receptors (NRs), which regulate the expression of various genes by binding to DNA either as a monomer or a heterodimer with retinoid x receptor. AREAS COVERED FXR affects several metabolic pathways through its specific target genes, regulating bile acid (BA) synthesis and homeostasis, glucose and lipid metabolism, also exhibiting a crucial role in intestinal bacterial growth and liver regeneration. Additionally, FXR is involved in the pathogenesis of different cholestatic diseases, as well as non-alcoholic fatty liver disease, inflammatory bowel disease (IBD) and primary idiopathic BA malabsorption. EXPERT OPINION Analyses of certain FXR polymorphisms revealed associations with clinical phenotypes and susceptibility to various human diseases. FXR single-nucleotide polymorphisms seem to be correlated with differences in glucose homeostasis, gallstone formation, intrahepatic cholestasis of pregnancy, IBD and therapeutic response to hypolipidemic therapy, among studied populations. Unfortunately, little data are still available and more studies remain to be done to determine the contribution of FXR polymorphisms in estimating risk factors and clinical outcomes for several diseases.
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Affiliation(s)
- Ioannis Koutsounas
- National and Kapodistrian University of Athens, First Department of Pathology, Medical School , Athens , Greece
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