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Cui H, Shi Q, Macarios CM, Schimmel P. Metabolic regulation of mRNA splicing. Trends Cell Biol 2024:S0962-8924(24)00025-4. [PMID: 38431493 DOI: 10.1016/j.tcb.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 03/05/2024]
Abstract
Alternative mRNA splicing enables the diversification of the proteome from a static genome and confers plasticity and adaptiveness on cells. Although this is often explored in development, where hard-wired programs drive the differentiation and specialization, alternative mRNA splicing also offers a way for cells to react to sudden changes in outside stimuli such as small-molecule metabolites. Fluctuations in metabolite levels and availability in particular convey crucial information to which cells react and adapt. We summarize and highlight findings surrounding the metabolic regulation of mRNA splicing. We discuss the principles underlying the biochemistry and biophysical properties of mRNA splicing, and propose how these could intersect with metabolite levels. Further, we present examples in which metabolites directly influence RNA-binding proteins and splicing factors. We also discuss the interplay between alternative mRNA splicing and metabolite-responsive signaling pathways. We hope to inspire future research to obtain a holistic picture of alternative mRNA splicing in response to metabolic cues.
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Affiliation(s)
- Haissi Cui
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada.
| | - Qingyu Shi
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada
| | | | - Paul Schimmel
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, CA 92037, USA.
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2
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Ruppert PMM, Kersten S. Mechanisms of hepatic fatty acid oxidation and ketogenesis during fasting. Trends Endocrinol Metab 2024; 35:107-124. [PMID: 37940485 DOI: 10.1016/j.tem.2023.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/02/2023] [Accepted: 10/04/2023] [Indexed: 11/10/2023]
Abstract
Fasting is part of many weight management and health-boosting regimens. Fasting causes substantial metabolic adaptations in the liver that include the stimulation of fatty acid oxidation and ketogenesis. The induction of fatty acid oxidation and ketogenesis during fasting is mainly driven by interrelated changes in plasma levels of various hormones and an increase in plasma nonesterified fatty acid (NEFA) levels and is mediated transcriptionally by the peroxisome proliferator-activated receptor (PPAR)α, supported by CREB3L3 (cyclic AMP-responsive element-binding protein 3 like 3). Compared with men, women exhibit higher ketone levels during fasting, likely due to higher NEFA availability, suggesting that the metabolic response to fasting shows sexual dimorphism. Here, we synthesize the current molecular knowledge on the impact of fasting on hepatic fatty acid oxidation and ketogenesis.
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Affiliation(s)
- Philip M M Ruppert
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5000 C Odense, Denmark
| | - Sander Kersten
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition and Health, Wageningen University, 6708 WE Wageningen, The Netherlands; Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA.
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3
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Zhang M, Xiao B, Chen X, Ou B, Wang S. Physical exercise plays a role in rebalancing the bile acids of enterohepatic axis in non-alcoholic fatty liver disease. Acta Physiol (Oxf) 2024; 240:e14065. [PMID: 38037846 DOI: 10.1111/apha.14065] [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: 05/26/2023] [Revised: 10/09/2023] [Accepted: 11/15/2023] [Indexed: 12/02/2023]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is considered as one of the most common diseases of lipid metabolism disorders, which is closely related to bile acids disorders and gut microbiota disorders. Bile acids are synthesized from cholesterol in the liver, and processed by gut microbiota in intestinal tract, and participate in metabolic regulation through the enterohepatic circulation. Bile acids not only promote the consumption and absorption of intestinal fat but also play an important role in biological metabolic signaling network, affecting fat metabolism and glucose metabolism. Studies have demonstrated that exercise plays an important role in regulating the composition and function of bile acid pool in enterohepatic axis, which maintains the homeostasis of the enterohepatic circulation and the health of the host gut microbiota. Exercise has been recommended by several health guidelines as the first-line intervention for patients with NAFLD. Can exercise alter bile acids through the microbiota in the enterohepatic axis? If so, regulating bile acids through exercise may be a promising treatment strategy for NAFLD. However, the specific mechanisms underlying this potential connection are largely unknown. Therefore, in this review, we tried to review the relationship among NAFLD, physical exercise, bile acids, and gut microbiota through the existing data and literature, highlighting the role of physical exercise in rebalancing bile acid and microbial dysbiosis.
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Affiliation(s)
- Minyu Zhang
- School of Physical Education and Sports Science, South China Normal University, Guangzhou, China
| | - Biyang Xiao
- College of Life Sciences, Zhaoqing University, Zhaoqing, China
| | - Xiaoqi Chen
- College of Life Sciences, Zhaoqing University, Zhaoqing, China
| | - Bingming Ou
- College of Life Sciences, Zhaoqing University, Zhaoqing, China
- School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, China
| | - Songtao Wang
- School of Physical Education and Sports Science, South China Normal University, Guangzhou, China
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4
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Jobbins AM, Yu S, Paterson HAB, Maude H, Kefala-Stavridi A, Speck C, Cebola I, Vernia S. Pre-RNA splicing in metabolic homeostasis and liver disease. Trends Endocrinol Metab 2023; 34:823-837. [PMID: 37673766 DOI: 10.1016/j.tem.2023.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/07/2023] [Accepted: 08/07/2023] [Indexed: 09/08/2023]
Abstract
The liver plays a key role in sensing nutritional and hormonal inputs to maintain metabolic homeostasis. Recent studies into pre-mRNA splicing and alternative splicing (AS) and their effects on gene expression have revealed considerable transcriptional complexity in the liver, both in health and disease. While the contribution of these mechanisms to cell and tissue identity is widely accepted, their role in physiological and pathological contexts within tissues is just beginning to be appreciated. In this review, we showcase recent studies on the splicing and AS of key genes in metabolic pathways in the liver, the effect of metabolic signals on the spliceosome, and therapeutic intervention points based on RNA splicing.
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Affiliation(s)
- Andrew M Jobbins
- MRC (Medical Research Council) London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK; Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Sijia Yu
- MRC (Medical Research Council) London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK; Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Helen A B Paterson
- MRC (Medical Research Council) London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK; Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Hannah Maude
- Section of Genetics and Genomics, Department of Metabolism, Digestion and Reproduction, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Antonia Kefala-Stavridi
- MRC (Medical Research Council) London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK; Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Christian Speck
- MRC (Medical Research Council) London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK; Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Inês Cebola
- Section of Genetics and Genomics, Department of Metabolism, Digestion and Reproduction, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Santiago Vernia
- MRC (Medical Research Council) London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK; Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.
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Ma YN, Jiang X, Tang W, Song P. Influence of intermittent fasting on autophagy in the liver. Biosci Trends 2023; 17:335-355. [PMID: 37661370 DOI: 10.5582/bst.2023.01207] [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] [Indexed: 09/05/2023]
Abstract
Studies have found that intermittent fasting (IF) can prevent diabetes, cancer, heart disease, and neuropathy, while in humans it has helped to alleviate metabolic syndrome, asthma, rheumatoid arthritis, Alzheimer's disease, and many other disorders. IF involves a series of coordinated metabolic and hormonal changes to maintain the organism's metabolic balance and cellular homeostasis. More importantly, IF can activate hepatic autophagy, which is important for maintaining cellular homeostasis and energy balance, quality control, cell and tissue remodeling, and defense against extracellular damage and pathogens. IF affects hepatic autophagy through multiple interacting pathways and molecular mechanisms, including adenosine monophosphate (AMP)-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), silent mating-type information regulatory 2 homolog-1 (SIRT1), peroxisomal proliferator-activated receptor alpha (PPARα) and farnesoid X receptor (FXR), as well as signaling pathways and molecular mechanisms such as glucagon and fibroblast growth factor 21 (FGF21). These pathways can stimulate the pro-inflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α), play a cytoprotective role, downregulate the expression of aging-related molecules, and prevent the development of steatosis-associated liver tumors. By influencing the metabolism of energy and oxygen radicals as well as cellular stress response systems, IF protects hepatocytes from genetic and environmental factors. By activating hepatic autophagy, IF has a potential role in treating a variety of liver diseases, including non-alcoholic fatty liver disease, drug-induced liver injury, viral hepatitis, hepatic fibrosis, and hepatocellular carcinoma. A better understanding of the effects of IF on liver autophagy may lead to new approaches for the prevention and treatment of liver disease.
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Affiliation(s)
- Ya-Nan Ma
- Department of Gastroenterology, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, Haikou, China
- Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan
| | - Xuemei Jiang
- Department of Gastroenterology, Hainan General Hospital, Hainan Affiliated Hospital of Hainan Medical University, Haikou, China
| | - Wei Tang
- International Health Care Center, National Center for Global Health and Medicine, Tokyo, Japan
- Hepato-Biliary-Pancreatic Surgery Division, Department of Surgery, The University of Tokyo Hospital, Tokyo, Japan
| | - Peipei Song
- Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan
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Rausch M, Samodelov SL, Visentin M, Kullak-Ublick GA. The Farnesoid X Receptor as a Master Regulator of Hepatotoxicity. Int J Mol Sci 2022; 23:ijms232213967. [PMID: 36430444 PMCID: PMC9695947 DOI: 10.3390/ijms232213967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/07/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022] Open
Abstract
The nuclear receptor farnesoid X receptor (FXR, NR1H4) is a bile acid (BA) sensor that links the enterohepatic circuit that regulates BA metabolism and elimination to systemic lipid homeostasis. Furthermore, FXR represents a real guardian of the hepatic function, preserving, in a multifactorial fashion, the integrity and function of hepatocytes from chronic and acute insults. This review summarizes how FXR modulates the expression of pathway-specific as well as polyspecific transporters and enzymes, thereby acting at the interface of BA, lipid and drug metabolism, and influencing the onset and progression of hepatotoxicity of varying etiopathogeneses. Furthermore, this review article provides an overview of the advances and the clinical development of FXR agonists in the treatment of liver diseases.
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Panzitt K, Zollner G, Marschall HU, Wagner M. Recent advances on FXR-targeting therapeutics. Mol Cell Endocrinol 2022; 552:111678. [PMID: 35605722 DOI: 10.1016/j.mce.2022.111678] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 04/25/2022] [Accepted: 04/27/2022] [Indexed: 12/25/2022]
Abstract
The bile acid receptor FXR has emerged as a bona fide drug target for chronic cholestatic and metabolic liver diseases, ahead of all non-alcoholic fatty liver disease (NAFLD). FXR is highly expressed in the liver and intestine and activation at both sites differentially contributes to its desired metabolic effects. Unrestricted FXR activation, however, also comes along with undesired effects such as a pro-atherogenic lipid profile, pruritus and hepatocellular toxicity under certain conditions. Several pre-clinical studies have confirmed the potency of FXR activation for cholestatic and metabolic liver diseases, but overall it remains still open whether selective activation of intestinal FXR is advantageous over pan-FXR activation and whether restricted or modulated FXR activation can limit some of the side effects. Even more, FXR antagonist also bear the potential as intestinal-selective drugs in NAFLD models. In this review we will discuss the molecular prerequisites for FXR activation, pan-FXR activation and intestinal FXR in/activation from a therapeutic point of view, different steroidal and non-steroidal FXR agonists, ways to restrict FXR activation and finally what we have learned from pre-clinical models and clinical trials with different FXR therapeutics.
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Affiliation(s)
- Katrin Panzitt
- Research Unit for Translational Nuclear Receptor Research, Medical University Graz, Graz, Austria; Division of Gastroenterology and Hepatology, Medical University Graz, Graz, Austria
| | - Gernot Zollner
- Division of Gastroenterology and Hepatology, Medical University Graz, Graz, Austria
| | - Hanns-Ulrich Marschall
- Department of Molecular and Clinical Medicine/Wallenberg Laboratory, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Martin Wagner
- Research Unit for Translational Nuclear Receptor Research, Medical University Graz, Graz, Austria; Division of Gastroenterology and Hepatology, Medical University Graz, Graz, Austria.
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Nara SJ, Jogi S, Cheruku S, Kandhasamy S, Jaipuri F, Kathi PK, Reddy S, Sarodaya S, Cook EM, Wang T, Sitkoff D, Rossi KA, Ruzanov M, Kiefer SE, Khan JA, Gao M, Reddy S, Sivaprasad Lvj S, Sane R, Mosure K, Zhuo X, Cao GG, Ziegler M, Azzara A, Krupinski J, Soars MG, Ellsworth BA, Wacker DA. Discovery of BMS-986339, a Pharmacologically Differentiated Farnesoid X Receptor Agonist for the Treatment of Nonalcoholic Steatohepatitis. J Med Chem 2022; 65:8948-8960. [PMID: 35704802 DOI: 10.1021/acs.jmedchem.2c00165] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
While several farnesoid X receptor (FXR) agonists under clinical investigation for the treatment of nonalcoholic steatohepatitis (NASH) have shown beneficial effects, adverse effects such as pruritus and elevation of plasma lipids have limited their clinical efficacy and approvability. Herein, we report the discovery and preclinical evaluation of compound 32 (BMS-986339), a nonbile acid FXR agonist with a pharmacologically distinct profile relative to our previously reported agonist BMS-986318. Compound 32 exhibited potent in vitro and in vivo activation of FXR, albeit with a context-dependent profile that resulted in tissue-selective effects in vivo. To our knowledge, this is the first report that demonstrates differential induction of Fgf15 in the liver and ileum by FXR agonists in vivo. Compound 32 demonstrated robust antifibrotic efficacy despite reduced activation of certain genes in the liver, suggesting that the additional pharmacology of BMS-986318 does not further benefit efficacy, possibly presenting an opportunity for reduced adverse effects. Further evaluation in humans is warranted to validate this hypothesis.
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Affiliation(s)
- Susheel J Nara
- Biocon-Bristol Myers Squibb Research and Development Center, Biocon Park, Plot No. 2 & 3, Bommasandra Phase IV, Jigani Link Road, Bangalore 560099, India
| | - Srinivas Jogi
- Biocon-Bristol Myers Squibb Research and Development Center, Biocon Park, Plot No. 2 & 3, Bommasandra Phase IV, Jigani Link Road, Bangalore 560099, India
| | - Srinivas Cheruku
- Biocon-Bristol Myers Squibb Research and Development Center, Biocon Park, Plot No. 2 & 3, Bommasandra Phase IV, Jigani Link Road, Bangalore 560099, India
| | - Sarkunam Kandhasamy
- Biocon-Bristol Myers Squibb Research and Development Center, Biocon Park, Plot No. 2 & 3, Bommasandra Phase IV, Jigani Link Road, Bangalore 560099, India
| | - Firoz Jaipuri
- Biocon-Bristol Myers Squibb Research and Development Center, Biocon Park, Plot No. 2 & 3, Bommasandra Phase IV, Jigani Link Road, Bangalore 560099, India
| | - Pavan Kalyan Kathi
- Biocon-Bristol Myers Squibb Research and Development Center, Biocon Park, Plot No. 2 & 3, Bommasandra Phase IV, Jigani Link Road, Bangalore 560099, India
| | - Subba Reddy
- Biocon-Bristol Myers Squibb Research and Development Center, Biocon Park, Plot No. 2 & 3, Bommasandra Phase IV, Jigani Link Road, Bangalore 560099, India
| | - Sanket Sarodaya
- Biocon-Bristol Myers Squibb Research and Development Center, Biocon Park, Plot No. 2 & 3, Bommasandra Phase IV, Jigani Link Road, Bangalore 560099, India
| | - Erica M Cook
- Departments of Small Molecule Drug Discovery, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Tao Wang
- Departments of Small Molecule Drug Discovery, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Doree Sitkoff
- Departments of Small Molecule Drug Discovery, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Karen A Rossi
- Departments of Small Molecule Drug Discovery, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Max Ruzanov
- Departments of Small Molecule Drug Discovery, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Susan E Kiefer
- Departments of Small Molecule Drug Discovery, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Javed A Khan
- Departments of Small Molecule Drug Discovery, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Mian Gao
- Discovery Biotherapeutics, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Satyanarayana Reddy
- Biocon-Bristol Myers Squibb Research and Development Center, Biocon Park, Plot No. 2 & 3, Bommasandra Phase IV, Jigani Link Road, Bangalore 560099, India
| | - Sankara Sivaprasad Lvj
- Biocon-Bristol Myers Squibb Research and Development Center, Biocon Park, Plot No. 2 & 3, Bommasandra Phase IV, Jigani Link Road, Bangalore 560099, India
| | - Ramola Sane
- Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Pharmaceutical Research Institute, 100 Binney Street, Cambridge, Massachusetts 02142, United States
| | - Kathy Mosure
- Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Pharmaceutical Research Institute, 100 Binney Street, Cambridge, Massachusetts 02142, United States
| | - Xiaoliang Zhuo
- Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Pharmaceutical Research Institute, 100 Binney Street, Cambridge, Massachusetts 02142, United States
| | - Gary G Cao
- Discovery Biology, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Milinda Ziegler
- Discovery Biology, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Anthony Azzara
- Discovery Biology, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - John Krupinski
- Discovery Biology, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Matthew G Soars
- Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Pharmaceutical Research Institute, 100 Binney Street, Cambridge, Massachusetts 02142, United States
| | - Bruce A Ellsworth
- Departments of Small Molecule Drug Discovery, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
| | - Dean A Wacker
- Departments of Small Molecule Drug Discovery, Bristol-Myers Squibb, Pharmaceutical Research Institute, P.O. Box 5400, Princeton, New Jersey 08543-5400, United States
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Zhou W, Anakk S. Enterohepatic and non-canonical roles of farnesoid X receptor in controlling lipid and glucose metabolism. Mol Cell Endocrinol 2022; 549:111616. [PMID: 35304191 PMCID: PMC9245558 DOI: 10.1016/j.mce.2022.111616] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 01/24/2022] [Indexed: 12/11/2022]
Abstract
Farnesoid X receptor (FXR) is a nuclear receptor that transcriptionally regulates bile acid homeostasis along with nutrient metabolism. In addition to the gastrointestinal (GI) tract, FXR expression has been widely noted in kidney, adrenal gland, pancreas, adipose, skeletal muscle, heart, and brain. Except for the liver and gut, the relevance of FXR signaling in metabolism in other tissues remains poorly understood. This review examines the classical and non-canonical tissue-specific roles of FXR in regulating, lipids, and glucose homeostasis under normal and diseased states. FXR activation has been reported to be protective against cholestasis, nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH), type 2 diabetes, cardiovascular and kidney diseases. Several ongoing clinical trials are investigating FXR ligands as a therapeutic target for primary biliary cholangitis (PBC) and NASH, which substantiate the significance of FXR signaling in modulating metabolic processes. This review highlights that FXR ligands, albeit an attractive therapeutic target for treating metabolic diseases, tissue-specific modulation of FXR may be the key to overcoming some of the adverse clinical effects.
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Affiliation(s)
- Weinan Zhou
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Sayeepriyadarshini Anakk
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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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: 40] [Impact Index Per Article: 20.0] [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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Rodrigues JS, Faria-Pereira A, Camões SP, Serras AS, Morais VA, Ruas JL, Miranda JP. Improving human mesenchymal stem cell-derived hepatic cell energy metabolism by manipulating glucose homeostasis and glucocorticoid signaling. Front Endocrinol (Lausanne) 2022; 13:1043543. [PMID: 36714559 PMCID: PMC9880320 DOI: 10.3389/fendo.2022.1043543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 11/24/2022] [Indexed: 01/14/2023] Open
Abstract
INTRODUCTION The development of reliable hepatic in vitro models may provide insights into disease mechanisms, linking hepatocyte dysmetabolism and related pathologies. However, several of the existing models depend on using high concentrations of hepatocyte differentiation-promoting compounds, namely glucose, insulin, and dexamethasone, which is among the reasons that have hampered their use for modeling metabolism-related diseases. This work focused on modulating glucose homeostasis and glucocorticoid concentration to improve the suitability of a mesenchymal stem-cell (MSC)-derived hepatocyte-like cell (HLC) human model for studying hepatic insulin action and disease modeling. METHODS We have investigated the role of insulin, glucose and dexamethasone on mitochondrial function, insulin signaling and carbohydrate metabolism, namely AKT phosphorylation, glycogen storage ability, glycolysis and gluconeogenesis, as well as fatty acid oxidation and bile acid metabolism gene expression in HLCs. In addition, we evaluated cell morphological features, albumin and urea production, the presence of hepatic-specific markers, biotransformation ability and mitochondrial function. RESULTS Using glucose, insulin and dexamethasone levels close to physiological concentrations improved insulin responsiveness in HLCs, as demonstrated by AKT phosphorylation, upregulation of glycolysis and downregulation of Irs2 and gluconeogenesis and fatty acid oxidation pathways. Ammonia detoxification, EROD and UGT activities and sensitivity to paracetamol cytotoxicity were also enhanced under more physiologically relevant conditions. CONCLUSION HLCs kept under reduced concentrations of glucose, insulin and dexamethasone presented an improved hepatic phenotype and insulin sensitivity demonstrating superior potential as an in vitro platform for modeling energy metabolism-related disorders, namely for the investigation of the insulin signaling pathway.
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Affiliation(s)
- Joana Saraiva Rodrigues
- Research Institute for Medicines (imed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal
| | - Andreia Faria-Pereira
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Sérgio Póvoas Camões
- Research Institute for Medicines (imed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal
| | - Ana Sofia Serras
- Research Institute for Medicines (imed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal
| | - Vanessa Alexandra Morais
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Jorge Lira Ruas
- Department of Physiology and Pharmacology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Joana Paiva Miranda
- Research Institute for Medicines (imed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal
- *Correspondence: Joana Paiva Miranda,
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12
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Ma Y, Tan Z, Li Q, Fan W, Chen G, Bin Y, Zhou Y, Yi J, Luo X, Tan J, Si Z, Li J. Combined Analysis of Expression Profiles in a Mouse Model and Patients Identified BHMT2 as a New Regulator of Lipid Metabolism in Metabolic-Associated Fatty Liver Disease. Front Cell Dev Biol 2021; 9:741710. [PMID: 34869329 PMCID: PMC8636031 DOI: 10.3389/fcell.2021.741710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 10/19/2021] [Indexed: 01/02/2023] Open
Abstract
Metabolic associated fatty liver disease (MAFLD) is associated with obesity, type 2 diabetes mellitus, and other metabolic syndromes. Farnesoid X receptor (FXR, NR1H4) plays a prominent role in hepatic lipid metabolism. This study combined the expression of liver genes in FXR knockout (KO) mice and MAFLD patients to identify new pathogenic pathways for MAFLD based on genome-wide transcriptional profiling. In addition, the roles of new target genes in the MAFLD pathogenic pathway were also explored. Two groups of differentially expressed genes were obtained from FXR-KO mice and MAFLD patients by transcriptional analysis of liver tissue samples. The similarities and differences between the two groups of differentially expressed genes were analyzed to identify novel pathogenic pathways and target genes. After the integration analysis of differentially expressed genes, we identified 134 overlapping genes, many of which have been reported to play an important role in lipid metabolism. Our unique analysis method of comparing differential gene expression between FXR-KO mice and patients with MAFLD is useful to identify target genes and pathways that may be strongly implicated in the pathogenesis of MAFLD. The overlapping genes with high specificity were screened using the Gene Expression Omnibus (GEO) database. Through comparison and analysis with the GEO database, we determined that BHMT2 and PKLR could be highly correlated with MAFLD. Clinical data analysis and RNA interference testing in vitro confirmed that BHMT2 may a new regulator of lipid metabolism in MAFLD pathogenesis. These results may provide new ideas for understanding the pathogenesis of MAFLD and thus provide new targets for the treatment of MAFLD.
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Affiliation(s)
- Yongqiang Ma
- Department of Liver Transplant, Second Xiangya Hospital, Central South University, Changsha, China.,Transplant Medical Research Center, Second Xiangya Hospital, Central South University, Changsha, China
| | - Zhi Tan
- Department of Gastroenterology, The First Hospital of Changsha, Changsha, China
| | - Qiang Li
- Department of Liver Transplant, Second Xiangya Hospital, Central South University, Changsha, China.,Transplant Medical Research Center, Second Xiangya Hospital, Central South University, Changsha, China
| | - Wenling Fan
- Department of Gastroenterology, The First Hospital of Changsha, Changsha, China
| | - Guangshun Chen
- Department of Liver Transplant, Second Xiangya Hospital, Central South University, Changsha, China.,Transplant Medical Research Center, Second Xiangya Hospital, Central South University, Changsha, China
| | - Yangyang Bin
- Department of Liver Transplant, Second Xiangya Hospital, Central South University, Changsha, China
| | - Yi Zhou
- Department of Liver Transplant, Second Xiangya Hospital, Central South University, Changsha, China
| | - Junfang Yi
- Department of Liver Transplant, Second Xiangya Hospital, Central South University, Changsha, China
| | - Xiaohua Luo
- Department of Liver Transplant, Second Xiangya Hospital, Central South University, Changsha, China
| | - Jieqiong Tan
- Center for Medical Genetics, School of Life Science, Central South University, Changsha, China
| | - Zhongzhou Si
- Department of Liver Transplant, Second Xiangya Hospital, Central South University, Changsha, China.,Transplant Medical Research Center, Second Xiangya Hospital, Central South University, Changsha, China
| | - Jiequn Li
- Department of Liver Transplant, Second Xiangya Hospital, Central South University, Changsha, China.,Transplant Medical Research Center, Second Xiangya Hospital, Central South University, Changsha, China
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13
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FXR, a Key Regulator of Lipid Metabolism, Is Inhibited by ER Stress-Mediated Activation of JNK and p38 MAPK in Large Yellow Croakers ( Larimichthys crocea) Fed High Fat Diets. Nutrients 2021; 13:nu13124343. [PMID: 34959897 PMCID: PMC8706856 DOI: 10.3390/nu13124343] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 11/26/2021] [Accepted: 11/26/2021] [Indexed: 12/13/2022] Open
Abstract
High-fat diets induced abnormal lipid accumulation in the liver of cultured fish that caused body damage and diseases. The purpose of this research was to investigate the role and mechanism of farnesoid X receptor (FXR) in regulating lipid metabolism and to determine how high-fat diets affect FXR expression in large yellow croakers. The results showed that ligand-meditated FXR-activation could prevent abnormal lipid accumulation in the liver and hepatocytes of large yellow croakers. FXR activation increased the expression of lipid catabolism-related genes while decreasing the expression of lipogenesis-related genes. Further investigation found that the promoter activity of proliferator-activated receptor α (PPARα) could be increased by croaker FXR. Through the influence of SHP on LXR, FXR indirectly decreased the promoter activity of sterol regulatory element binding protein 1 (SREBP1) in large yellow croakers. Furthermore, the findings revealed that endoplasmic reticulum (ER)-stress-induced-activation of JNK and P38 MAPK participated in the reduction of FXR induced by high-fat diets. Then, hepatocyte nuclear factor 1α (HNF1α) was confirmed to be an FXR regulator in large yellow croaker, and it was reduced by high-fat diets and ER stress. In addition, co-expression of c-Jun with HNF1α inhibited the effect of HNF1α on FXR promoter, and suppression of P38 MAPK could relieve the HNF1α expression reduction caused by ER stress activation. In summary, the present study showed that FXR mediated lipid metabolism can prevent abnormal lipid accumulation through regulating PPARα and SREBP1 in large yellow croakers, while high-fat diets can suppress FXR expression by ER stress mediated-activation of JNK and P38 MAPK pathways. This research could benefit the study of FXR functions in vertebrate evolution and the development of therapy or preventative methods for nutrition-related disorders.
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14
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Zhou JL, Zhao YZ, Wang SS, Chen MX, Zhou S, Chen C. RNA Splicing: A Versatile Regulatory Mechanism in Pediatric Liver Diseases. Front Mol Biosci 2021; 8:725308. [PMID: 34651015 PMCID: PMC8505697 DOI: 10.3389/fmolb.2021.725308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/23/2021] [Indexed: 12/03/2022] Open
Abstract
With the development of high-throughput sequencing technology, the posttranscriptional mechanism of alternative splicing is becoming better understood. From decades of studies, alternative splicing has been shown to occur in multiple tissues, including the brain, heart, testis, skeletal muscle, and liver. This regulatory mechanism plays an important role in physiological functions in most liver diseases. Currently, due to the absence of symptoms, chronic pediatric liver diseases have a significant impact on public health. Furthermore, the progression of the disease is accelerated in children, leading to severe damage to their liver tissue if no precautions are taken. To this end, this review article summarizes the current knowledge of alternative splicing in pediatric liver diseases, paying special attention to liver damage in the child stage. The discussion of the regulatory role of splicing in liver diseases and its potential as a new therapeutic target is also included.
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Affiliation(s)
- Jian-Li Zhou
- Division of Gastroenterology, Shenzhen Children's Hospital, Shenzhen, China
| | - Yu-Zhen Zhao
- Division of Gastroenterology, Shenzhen Children's Hospital, Shenzhen, China
| | - Shan-Shan Wang
- School of Life Sciences and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou, China
| | - Mo-Xian Chen
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, China
| | - Shaoming Zhou
- Division of Gastroenterology, Shenzhen Children's Hospital, Shenzhen, China
| | - Chen Chen
- Department of Infectious Disease, Nanjing Second Hospital, Nanjing University of Chinese Medicine, Nanjing, China
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15
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Abstract
Bile acids (BAs) are a family of hydroxylated steroids secreted by the liver that aid in the breakdown and absorption of dietary fats. BAs also function as nutrient and inflammatory signaling molecules, acting through cognate receptors, to coordinate host metabolism. Commensal bacteria in the gastrointestinal tract are functional modifiers of the BA pool, affecting composition and abundance. Deconjugation of host BAs creates a molecular network that inextricably links gut microtia with their host. In this review we highlight the roles of BAs in mediating this mutualistic relationship with a focus on those events that impact host physiology and metabolism.
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Affiliation(s)
- James C Poland
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - C Robb Flynn
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
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16
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Mukha A, Kalkhoven E, van Mil SWC. Splice variants of metabolic nuclear receptors: Relevance for metabolic disease and therapeutic targeting. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166183. [PMID: 34058349 DOI: 10.1016/j.bbadis.2021.166183] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/17/2021] [Accepted: 05/25/2021] [Indexed: 12/13/2022]
Abstract
Metabolic nuclear receptors are ligand-activated transcription factors which control a wide range of metabolic processes and signaling pathways in response to nutrients and xenobiotics. Targeting these NRs is at the forefront of our endeavours to generate novel treatment options for diabetes, metabolic syndrome and fatty liver disease. Numerous splice variants have been described for these metabolic receptors. Structural changes, as a result of alternative splicing, lead to functional differences among NR isoforms, resulting in the regulation of different metabolic pathways by these NR splice variants. In this review, we describe known splice variants of FXR, LXRs, PXR, RXR, LRH-1, CAR and PPARs. We discuss their structure and functions, and elaborate on the regulation of splice variant abundance by nutritional signals. We conclude that NR splice variants pose an intriguing new layer of complexity in metabolic signaling, which needs to be taken into account in the development of treatment strategies for metabolic diseases.
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Affiliation(s)
- Anna Mukha
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands
| | - Eric Kalkhoven
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands
| | - Saskia W C van Mil
- Center for Molecular Medicine, UMC Utrecht and Utrecht University, Utrecht, the Netherlands.
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17
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Fiorucci S, Biagioli M, Baldoni M, Ricci P, Sepe V, Zampella A, Distrutti E. The identification of farnesoid X receptor modulators as treatment options for nonalcoholic fatty liver disease. Expert Opin Drug Discov 2021; 16:1193-1208. [PMID: 33849361 DOI: 10.1080/17460441.2021.1916465] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION The farnesoid-x-receptor (FXR) is a ubiquitously expressed nuclear receptor selectively activated by primary bile acids. AREA COVERED FXR is a validated pharmacological target. Herein, the authors review preclinical and clinical data supporting the development of FXR agonists in the treatment of nonalcoholic fatty liver disease. EXPERT OPINION Development of systemic FXR agonists to treat the metabolic liver disease has been proven challenging because the side effects associated with these agents including increased levels of cholesterol and LDL-c and reduced HDL-c raising concerns over their long-term cardiovascular safety. Additionally, pruritus has emerged as a common, although poorly explained, dose-related side effect with all FXR ligands, but is especially common with OCA. FXR agonists that are currently undergoing phase 2/3 trials are cilofexor, tropifexor, nidufexor and MET409. Some of these agents are currently being developed as combination therapies with other agents including cenicriviroc, a CCR2/CCR5 inhibitor, or firsocostat an acetyl CoA carboxylase inhibitor. Additional investigations are needed to evaluate the beneficial effects of combination of these agents with statins. It is expected that in the coming years, FXR agonists will be developed as a combination therapy to minimize side effects and increase likelihood of success by targeting different metabolic pathways.
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Affiliation(s)
- Stefano Fiorucci
- Dipartimento Di Medicina E Chirurgia, Università Di Perugia, Perugia, Italy
| | - Michele Biagioli
- Dipartimento Di Medicina E Chirurgia, Università Di Perugia, Perugia, Italy
| | - Monia Baldoni
- Dipartimento Di Medicina E Chirurgia, Università Di Perugia, Perugia, Italy
| | - Patrizia Ricci
- Dipartimento Di Medicina E Chirurgia, Università Di Perugia, Perugia, Italy
| | - Valentina Sepe
- Department of Pharmacy University of Napoli, Federico II, Napoli, Italy
| | - Angela Zampella
- Department of Pharmacy University of Napoli, Federico II, Napoli, Italy
| | - Eleonora Distrutti
- SC Di Gastroenterologia Ed Epatologia, Azienda Ospedaliera Di Perugia, Perugia, Italy
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18
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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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19
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FXR in liver physiology: Multiple faces to regulate liver metabolism. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166133. [PMID: 33771667 DOI: 10.1016/j.bbadis.2021.166133] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 03/11/2021] [Accepted: 03/17/2021] [Indexed: 12/15/2022]
Abstract
The liver is the central metabolic hub which coordinates nutritional inputs and metabolic outputs. Food intake releases bile acids which can be sensed by the bile acid receptor FXR in the liver and the intestine. Hepatic and intestinal FXR coordinately regulate postprandial nutrient disposal in a network of interacting metabolic nuclear receptors. In this review we summarize and update the "classical roles" of FXR as a central integrator of the feeding state response, which orchestrates the metabolic processing of carbohydrates, lipids, proteins and bile acids. We also discuss more recent and less well studied FXR effects on amino acid, protein metabolism, autophagic turnover and inflammation. In addition, we summarize the recent understanding of how FXR signaling is affected by posttranslational modifications and by different FXR isoforms. These modifications and variations in FXR signaling might be considered when FXR is targeted pharmaceutically in clinical applications.
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20
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Fiorucci S, Distrutti E, Carino A, Zampella A, Biagioli M. Bile acids and their receptors in metabolic disorders. Prog Lipid Res 2021; 82:101094. [PMID: 33636214 DOI: 10.1016/j.plipres.2021.101094] [Citation(s) in RCA: 108] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/03/2021] [Accepted: 02/12/2021] [Indexed: 02/08/2023]
Abstract
Bile acids are a large family of atypical steroids which exert their functions by binding to a family of ubiquitous cell membrane and nuclear receptors. There are two main bile acid activated receptors, FXR and GPBAR1, that are exclusively activated by bile acids, while other receptors CAR, LXRs, PXR, RORγT, S1PR2and VDR are activated by bile acids in addition to other more selective endogenous ligands. In the intestine, activation of FXR and GPBAR1 promotes the release of FGF15/19 and GLP1 which integrate their signaling with direct effects exerted by theother receptors in target tissues. This network is tuned in a time ordered manner by circadian rhythm and is critical for the regulation of metabolic process including autophagy, fast-to-feed transition, lipid and glucose metabolism, energy balance and immune responses. In the last decade FXR ligands have entered clinical trials but development of systemic FXR agonists has been proven challenging because their side effects including increased levels of cholesterol and Low Density Lipoproteins cholesterol (LDL-c) and reduced High-Density Lipoprotein cholesterol (HDL-c). In addition, pruritus has emerged as a common, dose related, side effect of FXR ligands. Intestinal-restricted FXR and GPBAR1 agonists and dual FXR/GPBAR1 agonists have been developed. Here we review the last decade in bile acids physiology and pharmacology.
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Affiliation(s)
- Stefano Fiorucci
- Dipartimento di Medicina e Chirurgia, Università di Perugia, Perugia, Italy.
| | - Eleonora Distrutti
- SC di Gastroenterologia ed Epatologia, Azienda Ospedaliera di Perugia, Perugia, Italy
| | - Adriana Carino
- Dipartimento di Medicina e Chirurgia, Università di Perugia, Perugia, Italy
| | - Angela Zampella
- Department of Pharmacy, University of Napoli, Federico II, Napoli, Italy
| | - Michele Biagioli
- Dipartimento di Medicina e Chirurgia, Università di Perugia, Perugia, Italy
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21
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Anakk S, Dean AE. Fxr-alpha Skips Alternatively in Liver Metabolism. Gastroenterology 2020; 159:1655-1657. [PMID: 32926939 DOI: 10.1053/j.gastro.2020.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 09/09/2020] [Indexed: 12/02/2022]
Affiliation(s)
| | - Angela E Dean
- Division of Nutritional Sciences University of Illinois Urbana Champaign, Urbana, Illinois
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22
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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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23
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Wren SN, Donovan MG, Selmin OI, Doetschman TC, Romagnolo DF. A Villin-Driven Fxr Transgene Modulates Enterohepatic Bile Acid Homeostasis and Response to an n-6-Enriched High-Fat Diet. Int J Mol Sci 2020; 21:ijms21217829. [PMID: 33105708 PMCID: PMC7659968 DOI: 10.3390/ijms21217829] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 02/06/2023] Open
Abstract
A diet high in n-6 polyunsaturated fatty acids (PUFAs) may contribute to inflammation and tissue damage associated with obesity and pathologies of the colon and liver. One contributing factor may be dysregulation by n-6 fatty acids of enterohepatic bile acid (BA) metabolism. The farnesoid X receptor (FXR) is a nuclear receptor that regulates BA homeostasis in the liver and intestine. This study aims to compare the effects on FXR regulation and BA metabolism of a palm oil-based diet providing 28% energy (28%E) from fat and low n-6 linoleic acid (LA, 2.5%E) (CNTL) with those of a soybean oil-based diet providing 50%E from fat and high (28%E) in LA (n-6HFD). Wild-type (WT) littermates and a transgenic mouse line overexpressing the Fxrα1 isoform under the control of the intestine-specific Villin promoter (Fxrα1TG) were fed the CNTL or n-6HFD starting at weaning through 16 weeks of age. Compared to the CNTL diet, the n-6HFD supports higher weight gain in both WT and FxrαTG littermates; increases the expression of Fxrα1/2, and peroxisome proliferator-activated receptor-γ1 (Pparγ1) in the small intestine, Fxrα1/2 in the colon, and cytochrome P4507A1 (Cyp7a1) and small heterodimer protein (Shp) in the liver; and augments the levels of total BA in the liver, and primary chenodeoxycholic (CDCA), cholic (CA), and β-muricholic (βMCA) acid in the cecum. Intestinal overexpression of the Fxra1TG augments expression of Shp and ileal bile acid-binding protein (Ibabp) in the small intestine and Ibabp in the proximal colon. Conversely, it antagonizes n-6HFD-dependent accumulation of intestinal and hepatic CDCA and CA; hepatic levels of Cyp7a1; and expression of Pparγ in the small intestine. We conclude that intestinal Fxrα1 overexpression represses hepatic de novo BA synthesis and protects against n-6HFD-induced accumulation of human-specific primary bile acids in the cecum.
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Affiliation(s)
- Spencer N. Wren
- Department of Nutritional Sciences, The University of Arizona, Tucson, AZ 85721, USA; (S.N.W.); (O.I.S.)
| | - Micah G. Donovan
- Interdisciplinary Cancer Biology Graduate Program, The University of Arizona, Tucson, AZ 85724, USA;
| | - Ornella I. Selmin
- Department of Nutritional Sciences, The University of Arizona, Tucson, AZ 85721, USA; (S.N.W.); (O.I.S.)
- The University of Arizona Cancer Center, Tucson, AZ 85724, USA
| | - Tom C. Doetschman
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, AZ 85724, USA;
| | - Donato F. Romagnolo
- Department of Nutritional Sciences, The University of Arizona, Tucson, AZ 85721, USA; (S.N.W.); (O.I.S.)
- The University of Arizona Cancer Center, Tucson, AZ 85724, USA
- Correspondence: ; Tel.: +1-520-626-9108
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24
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Kumari A, Pal Pathak D, Asthana S. Bile acids mediated potential functional interaction between FXR and FATP5 in the regulation of Lipid Metabolism. Int J Biol Sci 2020; 16:2308-2322. [PMID: 32760200 PMCID: PMC7378638 DOI: 10.7150/ijbs.44774] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 05/17/2020] [Indexed: 02/06/2023] Open
Abstract
Perturbation in lipid homeostasis is one of the major bottlenecks in metabolic diseases, especially Non-alcoholic Fatty Liver Disease (NAFLD), which has emerged as a leading global cause of chronic liver disease. The bile acids (BAs) and their derivatives exert a variety of metabolic effects through complex and intertwined pathways, thus becoming the attractive target for metabolic syndrome treatment. To modulate the lipid homeostasis, the role of BAs, turn out to be paramount as it is essential for the absorption, transport of dietary lipids, regulation of metabolic enzymes and transporters that are essential for lipid modulation, flux, and excretion. The synthesis and transport of BAs (conjugated and unconjugated) is chiefly controlled by nuclear receptors and the uptake of long-chain fatty acids (LCFA) and BA conjugation via transporters. Among them, from in-vivo studies, farnesoid X receptor (FXR) and liver-specific fatty acid transport protein 5 (FATP5) have shown convincing evidence for their key roles in lipid homeostasis and reversal of fatty liver disease substantially. BAs have a wider range of biological effects as they are identified as modulators for FXR and FATP5 both and therefore hold a significant promise for altering the lipid content in the treatment of a metabolic disorder. BAs also have received noteworthy interest in drug delivery research due to its peculiar physicochemical properties and biocompatibility. Here, we are highlighting the connecting possibility of BAs as an agonist for FXR and antagonist for FATP5, paving an avenue to target them for designing synthetic small molecules for lipid homeostasis.
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Affiliation(s)
- Anita Kumari
- Translational Health Science and Technology Institute (THSTI), Faridabad, Haryana, India.,Delhi Pharmaceutical Sciences and Research University (DPSRU), New Delhi, India
| | - Dharam Pal Pathak
- Delhi Institute of Pharmaceutical Sciences and Research (DIPSAR), New Delhi, India.,Delhi Pharmaceutical Sciences and Research University (DPSRU), New Delhi, India
| | - Shailendra Asthana
- Translational Health Science and Technology Institute (THSTI), Faridabad, Haryana, India
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Cortés VA, Barrera F, Nervi F. Pathophysiological connections between gallstone disease, insulin resistance, and obesity. Obes Rev 2020; 21:e12983. [PMID: 31814283 DOI: 10.1111/obr.12983] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 10/28/2019] [Accepted: 11/13/2019] [Indexed: 12/12/2022]
Abstract
Obesity and cholesterol gallstone disease (GSD) are frequently coexisting diseases; therefore and considering the current worldwide obesity epidemics, a precise understanding of the pathophysiological relationships between GSD and insulin resistance (IR) is important. Classically, obesity has been understood as a risk factor for GSD and the gallbladder (GB) viewed as a simple bile reservoir, with no metabolic roles whatsoever. However, consistent evidence has showed that both GSD and cholecystectomy associates with fatty liver and IR, raising the possibility that the GB is indeed an organ with metabolic regulatory roles. Herein, we review the pathophysiological mechanisms by which GSD, IR, and obesity are interconnected, with emphasis in the actions of the GB as a regulator of bile acids kinetics and a hormone secreting organ, with metabolic actions at the systemic level. We also examine the relationships between increased hepatic lipogenic in IR states and GSD pathogenesis. We propose a model in which GSD and hepatic IR mutually interact to determine a state of dysregulated lipid and energy metabolism that potentiate the metabolic dysregulation of obesity.
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Affiliation(s)
- Víctor A Cortés
- Department of Nutrition, Diabetes and Metabolism, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Francisco Barrera
- Department of Gastroenterology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Flavio Nervi
- Department of Gastroenterology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
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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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Ticho AL, Malhotra P, Dudeja PK, Gill RK, Alrefai WA. Intestinal Absorption of Bile Acids in Health and Disease. Compr Physiol 2019; 10:21-56. [PMID: 31853951 PMCID: PMC7171925 DOI: 10.1002/cphy.c190007] [Citation(s) in RCA: 108] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The intestinal reclamation of bile acids is crucial for the maintenance of their enterohepatic circulation. The majority of bile acids are actively absorbed via specific transport proteins that are highly expressed in the distal ileum. The uptake of bile acids by intestinal epithelial cells modulates the activation of cytosolic and membrane receptors such as the farnesoid X receptor (FXR) and G protein-coupled bile acid receptor 1 (GPBAR1), which has a profound effect on hepatic synthesis of bile acids as well as glucose and lipid metabolism. Extensive research has focused on delineating the processes of bile acid absorption and determining the contribution of dysregulated ileal signaling in the development of intestinal and hepatic disorders. For example, a decrease in the levels of the bile acid-induced ileal hormone FGF15/19 is implicated in bile acid-induced diarrhea (BAD). Conversely, the increase in bile acid absorption with subsequent overload of bile acids could be involved in the pathophysiology of liver and metabolic disorders such as fatty liver diseases and type 2 diabetes mellitus. This review article will attempt to provide a comprehensive overview of the mechanisms involved in the intestinal handling of bile acids, the pathological implications of disrupted intestinal bile acid homeostasis, and the potential therapeutic targets for the treatment of bile acid-related disorders. Published 2020. Compr Physiol 10:21-56, 2020.
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Affiliation(s)
- Alexander L. Ticho
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Pooja Malhotra
- Division of Gastroenterology & Hepatology, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Pradeep K. Dudeja
- Division of Gastroenterology & Hepatology, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
- jesse Brown VA Medical Center, Chicago, Illinois, USA
| | - Ravinder K. Gill
- Division of Gastroenterology & Hepatology, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Waddah A. Alrefai
- Division of Gastroenterology & Hepatology, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
- jesse Brown VA Medical Center, Chicago, Illinois, USA
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Ruby MA, Massart J, Hunerdosse DM, Schönke M, Correia JC, Louie SM, Ruas JL, Näslund E, Nomura DK, Zierath JR. Human Carboxylesterase 2 Reverses Obesity-Induced Diacylglycerol Accumulation and Glucose Intolerance. Cell Rep 2017; 18:636-646. [PMID: 28099843 PMCID: PMC5276805 DOI: 10.1016/j.celrep.2016.12.070] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 11/18/2016] [Accepted: 12/20/2016] [Indexed: 02/01/2023] Open
Abstract
Serine hydrolases are a large family of multifunctional enzymes known to influence obesity. Here, we performed activity-based protein profiling to assess the functional level of serine hydrolases in liver biopsies from lean and obese humans in order to gain mechanistic insight into the pathophysiology of metabolic disease. We identified reduced hepatic activity of carboxylesterase 2 (CES2) and arylacetamide deacetylase (AADAC) in human obesity. In primary human hepatocytes, CES2 knockdown impaired glucose storage and lipid oxidation. In mice, obesity reduced CES2, whereas adenoviral delivery of human CES2 reversed hepatic steatosis, improved glucose tolerance, and decreased inflammation. Lipidomic analysis identified a network of CES2-regulated lipids altered in human and mouse obesity. CES2 possesses triglyceride and diacylglycerol lipase activities and displayed an inverse correlation with HOMA-IR and hepatic diacylglycerol concentrations in humans. Thus, decreased CES2 is a conserved feature of obesity and plays a causative role in the pathogenesis of obesity-related metabolic disturbances. Obesity decreases hepatic activity of AADAC and CES2 in humans CES2 depletion impairs lipid and glucose metabolism in primary human hepatocytes Human CES2 expression reverses hepatic steatosis and glucose intolerance in mice CES2 controls a hepatic lipid network dysregulated in human and mouse obesity
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Affiliation(s)
- Maxwell A Ruby
- Section for Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Julie Massart
- Section for Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Devon M Hunerdosse
- Departments of Chemistry, Molecular and Cell Biology, and Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Milena Schönke
- Section for Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Jorge C Correia
- Molecular and Cellular Exercise Physiology Unit, Department of Physiology and Pharmacology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Sharon M Louie
- Departments of Chemistry, Molecular and Cell Biology, and Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jorge L Ruas
- Molecular and Cellular Exercise Physiology Unit, Department of Physiology and Pharmacology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Erik Näslund
- Division of Surgery, Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Daniel K Nomura
- Departments of Chemistry, Molecular and Cell Biology, and Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Juleen R Zierath
- Section for Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, 17177 Stockholm, Sweden.
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Massafra V, van Mil SWC. Farnesoid X receptor: A "homeostat" for hepatic nutrient metabolism. Biochim Biophys Acta Mol Basis Dis 2017; 1864:45-59. [PMID: 28986309 DOI: 10.1016/j.bbadis.2017.10.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/27/2017] [Accepted: 10/02/2017] [Indexed: 02/06/2023]
Abstract
The Farnesoid X receptor (FXR) is a nuclear receptor activated by bile acids (BAs). BAs are amphipathic molecules that serve as fat solubilizers in the intestine under postprandial conditions. In the post-absorptive state, BAs bind FXR in the hepatocytes, which in turn provides feedback signals on BA synthesis and transport and regulates lipid, glucose and amino acid metabolism. Therefore, FXR acts as a homeostat of all three classes of nutrients, fats, sugars and proteins. Here we re-analyze the function of FXR in the perspective of nutritional metabolism, and discuss the role of FXR in liver energy homeostasis in postprandial, post-absorptive and fasting/starvation states. FXR, by regulating nutritional metabolism, represses autophagy in conditions of nutrient abundance, and controls the metabolic needs of proliferative cells. In addition, FXR regulates inflammation via direct effects and via its impact on nutrient metabolism. These functions indicate that FXR is an attractive therapeutic target for liver diseases.
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Affiliation(s)
- Vittoria Massafra
- Center for Molecular Medicine, UMC Utrecht, Utrecht, The Netherlands
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Mann JP, Feldstein AE, Nobili V. Update on lipid species and paediatric nonalcoholic fatty liver disease. Curr Opin Clin Nutr Metab Care 2017; 20:110-116. [PMID: 27906700 DOI: 10.1097/mco.0000000000000346] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE OF REVIEW To describe the recent advances in our understanding of fatty acids and lipids in paediatric nonalcoholic fatty liver disease (NAFLD) and their future implications. RECENT FINDINGS Data have been accumulated to suggest that ceramides are the main drivers of hepatic insulin resistance in NAFLD, and inhibition of ceramide synthesis improves histology in mice.Saturated fatty acids formed by de novo lipogenesis generate increased lipotoxicity compared with dietary-derived saturated fatty acids.Hepatic lipogenesis and associated insulin resistance have been found to be influenced by several novel proteins, including E2F1, cyclic AMP response element binding protein transcriptional coactivator 2, Raptor, and eukaryotic initiation factor 6. There are encouraging data from animal models that modulation of these could be therapeutic targets.Human and animal metabolomics and lipidomics data have been used to generate a lipid signature for NAFLD and nonalcoholic steatohepatitis. Serum lipidomics appears to correlate with hepatic lipidomics.Therapeutic trials of polyunsaturated fatty acids in children have had mixed results, with some reductions in noninvasive biomarkers. SUMMARY Multiple new pathways for drug targets have been identified, and use of lipidomics is likely to become a noninvasive method for assessing disease. However, much of the data for paediatric NAFLD are extrapolated from adult or animal studies.
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Affiliation(s)
- Jake P Mann
- aDepartment of Paediatrics, University of Cambridge, Cambridge, UK bDepartment of Pediatric Gastroenterology, University of California San Diego (UCSD) cRady Children's Hospital, San Diego, California, USA dHepatometabolic Unit eLiver Research Unit, Bambino Gesu Hospital, IRCCS, Rome, Italy
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Arab JP, Karpen SJ, Dawson PA, Arrese M, Trauner M. Bile acids and nonalcoholic fatty liver disease: Molecular insights and therapeutic perspectives. Hepatology 2017; 65:350-362. [PMID: 27358174 PMCID: PMC5191969 DOI: 10.1002/hep.28709] [Citation(s) in RCA: 396] [Impact Index Per Article: 56.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/09/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a burgeoning health problem worldwide and an important risk factor for both hepatic and cardiometabolic mortality. The rapidly increasing prevalence of this disease and of its aggressive form nonalcoholic steatohepatitis (NASH) will require novel therapeutic approaches to prevent disease progression to advanced fibrosis or cirrhosis and cancer. In recent years, bile acids have emerged as relevant signaling molecules that act at both hepatic and extrahepatic tissues to regulate lipid and carbohydrate metabolic pathways as well as energy homeostasis. Activation or modulation of bile acid receptors, such as the farnesoid X receptor and TGR5, and transporters, such as the ileal apical sodium-dependent bile acid transporter, appear to affect both insulin sensitivity and NAFLD/NASH pathogenesis at multiple levels, and these approaches hold promise as novel therapies. In the present review, we summarize current available data on the relationships of bile acids to NAFLD and the potential for therapeutically targeting bile-acid-related pathways to address this growing world-wide disease. (Hepatology 2017;65:350-362).
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Affiliation(s)
- Juan P. Arab
- Department of Gastroenterology, School of MedicinePontificia Universidad Católica de ChileSantiagoChile
| | - Saul J. Karpen
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Department of PediatricsEmory University School of MedicineAtlantaGAUSA
| | - Paul A. Dawson
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Department of PediatricsEmory University School of MedicineAtlantaGAUSA
| | - Marco Arrese
- Department of Gastroenterology, School of MedicinePontificia Universidad Católica de ChileSantiagoChile
| | - Michael Trauner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine IIIMedical University of ViennaViennaAustria
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Abstract
PURPOSE OF REVIEW The view on bile salts has evolved over the years from being regarded as simple detergents that aid intestinal absorption of fat-soluble nutrients to being important hormone-like integrators of metabolism. This review provides an update on the rapidly developing field of interactions between bile salts and lipid metabolism, with a particular emphasis on the underlying mechanisms. RECENT FINDINGS The nuclear receptor farnesoid X receptor (FXR) plays major roles in bile salt-mediated signaling pathways. The recent identification of novel FXR targets and factors involved in FXR signaling highlights the interactions of bile acids with lipid metabolism. Exciting data have been reported on the use of intestine-specific FXR agonists as well as antagonists. In addition, encouraging results for treatment of hepatic steatosis obtained with obeticholic acid in the FLINT trial underline the therapeutic potential of bile salt signaling and metabolism for the treatment of lipid disorders. SUMMARY Modulation of FXR activity appears to be a potent target, not only for improving bile salt homeostasis, but also to improve lipid metabolism. Depending on the metabolic context both, FXR agonists as well as antagonists, could prove to be of therapeutic benefit.
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Affiliation(s)
- Marleen Schonewille
- aDepartment of Pediatrics bDepartment of Laboratory Medicine, Center for Liver, Digestive and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen cAmsterdam Diabetes Center, Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands *Marleen Schonewille and Jan Freark de Boer contributed equally to the writing of this article
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