Role of Farnesoid X Receptor in the Enhancement of Canalicular Bile Acid Output and Excretion of Unconjugated Bile Acids: A Mechanism for Protection against Cholic Acid-Induced Liver Toxicity

2004 ◽  
Vol 312 (2) ◽  
pp. 759-766 ◽  
Author(s):  
Masaaki Miyata ◽  
Aki Tozawa ◽  
Hijiri Otsuka ◽  
Toshifumi Nakamura ◽  
Kiyoshi Nagata ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Cholic Acid ◽  
Liver Toxicity ◽  
Acid Output ◽  
Farnesoid X Receptor ◽  
Canalicular Bile

Coordinated induction of bile acid detoxification and alternative elimination in mice: role of FXR-regulated organic solute transporter-α/β in the adaptive response to bile acids

2006 ◽  
Vol 290 (5) ◽  
pp. G923-G932 ◽  
Author(s):  
Gernot Zollner ◽  
Martin Wagner ◽  
Tarek Moustafa ◽  
Peter Fickert ◽  
Dagmar Silbert ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Liver Toxicity ◽  
Farnesoid X Receptor ◽  
Multidrug Resistance Proteins ◽  
Organic Solute Transporter ◽  
Liver And Kidney ◽  
Organic Solute ◽  
Solute Transporter

The bile acid receptor farnesoid X receptor (FXR) is a key regulator of hepatic defense mechanisms against bile acids. A comprehensive study addressing the role of FXR in the coordinated regulation of adaptive mechanisms including biosynthesis, metabolism, and alternative export together with their functional significance is lacking. We therefore fed FXR knockout (FXR−/−) mice with cholic acid (CA) and ursodeoxycholic acid (UDCA). Bile acid synthesis and hydroxylation were assessed by real-time RT-PCR for cytochrome P-450 (Cyp)7a1, Cyp3a11, and Cyp2b10 and mass spectrometry-gas chromatography for determination of bile acid composition. Expression of the export systems multidrug resistance proteins (Mrp)4–6 in the liver and kidney and the recently identified basoalteral bile acid transporter, organic solute transporter (Ost-α/Ost-β), in the liver, kidney, and intestine was also investigated. CA and UDCA repressed Cyp7a1 in FXR+/+ mice and to lesser extents in FXR−/− mice and induced Cyp3a11 and Cyp2b10 independent of FXR. CA and UDCA were hydroxylated in both genotypes. CA induced Ost-α/Ost-β in the liver, kidney, and ileum in FXR+/+ but not FXR−/− mice, whereas UDCA had only minor effects. Mrp4 induction in the liver and kidney correlated with bile acid levels and was observed in UDCA-fed and CA-fed FXR−/− animals but not in CA-fed FXR+/+ animals. Mrp5/6 remained unaffected by bile acid treatment. In conclusion, we identified Ost-α/Ost-β as a novel FXR target. Absent Ost-α/Ost-β induction in CA-fed FXR−/− animals may contribute to increased liver injury in these animals. The induction of bile acid hydroxylation and Mrp4 was independent of FXR but could not counteract liver toxicity sufficiently. Limited effects of UDCA on Ost-α/Ost-β may jeopardize its therapeutic efficacy.

scholarly journals Role of Bile Acids in the Regulation of Food Intake, and Their Dysregulation in Metabolic Disease

Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1104
Author(s):  
Cong Xie ◽  
Weikun Huang ◽  
Richard L. Young ◽  
Karen L. Jones ◽  
Michael Horowitz ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Peptide Yy ◽  
Glycogen Synthesis ◽  
Hormone Secretion ◽  
Gastrointestinal Hormones ◽  
Farnesoid X Receptor ◽  
Gastrointestinal Hormone ◽  
Bile Acid Sequestrants

Bile acids are cholesterol-derived metabolites with a well-established role in the digestion and absorption of dietary fat. More recently, the discovery of bile acids as natural ligands for the nuclear farnesoid X receptor (FXR) and membrane Takeda G-protein-coupled receptor 5 (TGR5), and the recognition of the effects of FXR and TGR5 signaling have led to a paradigm shift in knowledge regarding bile acid physiology and metabolic health. Bile acids are now recognized as signaling molecules that orchestrate blood glucose, lipid and energy metabolism. Changes in FXR and/or TGR5 signaling modulates the secretion of gastrointestinal hormones including glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), hepatic gluconeogenesis, glycogen synthesis, energy expenditure, and the composition of the gut microbiome. These effects may contribute to the metabolic benefits of bile acid sequestrants, metformin, and bariatric surgery. This review focuses on the role of bile acids in energy intake and body weight, particularly their effects on gastrointestinal hormone secretion, the changes in obesity and T2D, and their potential relevance to the management of metabolic disorders.

scholarly journals Arbutin Alleviates the Liver Injury of α-Naphthylisothiocyanate-induced Cholestasis Through Farnesoid X Receptor Activation

2021 ◽  
Vol 9 ◽  
Author(s):  
Peijie Wu ◽  
Ling Qiao ◽  
Han Yu ◽  
Hui Ming ◽  
Chao Liu ◽  
...  
Keyword(s):  
Bile Acid ◽  
Liver Injury ◽  
Protective Effect ◽  
Bile Acids ◽  
Liver Toxicity ◽  
Enterohepatic Circulation ◽  
Receptor Activation ◽  
Farnesoid X Receptor ◽  
Bile Acid Metabolism ◽  
Cholestatic Diseases

Cholestasis is a kind of stressful syndrome along with liver toxicity, which has been demonstrated to be related to fibrosis, cirrhosis, even cholangiocellular or hepatocellular carcinomas. Cholestasis usually caused by the dysregulated metabolism of bile acids that possess high cellular toxicity and synthesized by cholesterol in the liver to undergo enterohepatic circulation. In cholestasis, the accumulation of bile acids in the liver causes biliary and hepatocyte injury, oxidative stress, and inflammation. The farnesoid X receptor (FXR) is regarded as a bile acid–activated receptor that regulates a network of genes involved in bile acid metabolism, providing a new therapeutic target to treat cholestatic diseases. Arbutin is a glycosylated hydroquinone isolated from medicinal plants in the genus Arctostaphylos, which has a variety of potentially pharmacological properties, such as anti-inflammatory, antihyperlipidemic, antiviral, antihyperglycemic, and antioxidant activity. However, the mechanistic contributions of arbutin to alleviate liver injury of cholestasis, especially its role on bile acid homeostasis via nuclear receptors, have not been fully elucidated. In this study, we demonstrate that arbutin has a protective effect on α-naphthylisothiocyanate–induced cholestasis via upregulation of the levels of FXR and downstream enzymes associated with bile acid homeostasis such as Bsep, Ntcp, and Sult2a1, as well as Ugt1a1. Furthermore, the regulation of these functional proteins related to bile acid homeostasis by arbutin could be alleviated by FXR silencing in L-02 cells. In conclusion, a protective effect could be supported by arbutin to alleviate ANIT-induced cholestatic liver toxicity, which was partly through the FXR pathway, suggesting arbutin may be a potential chemical molecule for the cholestatic disease.

scholarly journals MECHANISMS IN ENDOCRINOLOGY: Bile acid sequestrants in type 2 diabetes: potential effects on GLP1 secretion

2014 ◽  
Vol 171 (2) ◽  
pp. R47-R65 ◽  
Author(s):  
David P Sonne ◽  
Morten Hansen ◽  
Filip K Knop
Keyword(s):  
Type 2 Diabetes ◽  
Bile Acid ◽  
Bile Acids ◽  
G Protein ◽  
Farnesoid X Receptor ◽  
Bile Acid Metabolism ◽  
Bile Acid Sequestrants ◽  
G Protein Coupled

Bile acid sequestrants have been used for decades for the treatment of hypercholesterolaemia. Sequestering of bile acids in the intestinal lumen interrupts enterohepatic recirculation of bile acids, which initiate feedback mechanisms on the conversion of cholesterol into bile acids in the liver, thereby lowering cholesterol concentrations in the circulation. In the early 1990s, it was observed that bile acid sequestrants improved glycaemic control in patients with type 2 diabetes. Subsequently, several studies confirmed the finding and recently – despite elusive mechanisms of action – bile acid sequestrants have been approved in the USA for the treatment of type 2 diabetes. Nowadays, bile acids are no longer labelled as simple detergents necessary for lipid digestion and absorption, but are increasingly recognised as metabolic regulators. They are potent hormones, work as signalling molecules on nuclear receptors and G protein-coupled receptors and trigger a myriad of signalling pathways in many target organs. The most described and well-known receptors activated by bile acids are the farnesoid X receptor (nuclear receptor) and the G protein-coupled cell membrane receptor TGR5. Besides controlling bile acid metabolism, these receptors are implicated in lipid, glucose and energy metabolism. Interestingly, activation of TGR5 on enteroendocrine L cells has been suggested to affect secretion of incretin hormones, particularly glucagon-like peptide 1 (GLP1 (GCG)). This review discusses the role of bile acid sequestrants in the treatment of type 2 diabetes, the possible mechanism of action and the role of bile acid-induced secretion of GLP1 via activation of TGR5.

scholarly journals Therapeutic targeting of bile acids

2015 ◽  
Vol 309 (4) ◽  
pp. G209-G215 ◽  
Author(s):  
Michael Camilleri ◽  
Gregory J. Gores
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Farnesoid X Receptor ◽  
Major Theme ◽  
Bile Acid Malabsorption ◽  
Drug Of Choice ◽  
Bile Acid Receptor ◽  
Irritable Bowel ◽  
G Protein Coupled

The first objectives of this article are to review the structure, chemistry, and physiology of bile acids and the types of bile acid malabsorption observed in clinical practice. The second major theme addresses the classical or known properties of bile acids, such as the role of bile acid sequestration in the treatment of hyperlipidemia; the use of ursodeoxycholic acid in therapeutics, from traditional oriental medicine to being, until recently, the drug of choice in cholestatic liver diseases; and the potential for normalizing diverse bowel dysfunctions in irritable bowel syndrome, either by sequestering intraluminal bile acids for diarrhea or by delivering more bile acids to the colon to relieve constipation. The final objective addresses novel concepts and therapeutic opportunities such as the interaction of bile acids and the microbiome to control colonic infections, as in Clostridium difficile-associated colitis, and bile acid targeting of the farnesoid X receptor and G protein-coupled bile acid receptor 1 with consequent effects on energy expenditure, fat metabolism, and glycemic control.

scholarly journals Role of Organic Solute Transporter Alpha/Beta in Hepatotoxic Bile Acid Transport and Drug Interactions

2020 ◽  
Vol 176 (1) ◽  
pp. 34-45 ◽  
Author(s):  
James J Beaudoin ◽  
Jacqueline Bezençon ◽  
Noora Sjöstedt ◽  
John K Fallon ◽  
Kim L R Brouwer
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Farnesoid X Receptor ◽  
Acid Transport ◽  
Bile Acid Transport ◽  
Organic Solute Transporter ◽  
Organic Solute ◽  
The Impact ◽  
Solute Transporter

Abstract Organic solute transporter (OST) α/β is a key bile acid transporter expressed in various organs, including the liver under cholestatic conditions. However, little is known about the involvement of OSTα/β in bile acid-mediated drug-induced liver injury (DILI), a major safety concern in drug development. This study investigated whether OSTα/β preferentially transports more hepatotoxic, conjugated, primary bile acids and to what extent xenobiotics inhibit this transport. Kinetic studies with OSTα/β-overexpressing cells revealed that OSTα/β preferentially transported bile acids in the following order: taurochenodeoxycholate > glycochenodeoxycholate > taurocholate > glycocholate. The apparent half-maximal inhibitory concentrations for OSTα/β-mediated bile acid (5 µM) transport inhibition by fidaxomicin, troglitazone sulfate, and ethinyl estradiol were: 210, 334, and 1050 µM, respectively, for taurochenodeoxycholate; 97.6, 333, and 337 µM, respectively, for glycochenodeoxycholate; 140, 265, and 527 µM, respectively, for taurocholate; 59.8, 102, and 117 µM, respectively, for glycocholate. The potential role of OSTα/β in hepatocellular glycine-conjugated bile acid accumulation and cholestatic DILI was evaluated using sandwich-cultured human hepatocytes (SCHH). Treatment of SCHH with the farnesoid X receptor agonist chenodeoxycholate (100 µM) resulted in substantial OSTα/β induction, among other proteomic alterations, reducing glycochenodeoxycholate and glycocholate accumulation in cells+bile 4.0- and 4.5-fold, respectively. Treatment of SCHH with troglitazone and fidaxomicin together under cholestatic conditions resulted in increased hepatocellular toxicity compared with either compound alone, suggesting that OSTα/β inhibition may accentuate DILI. In conclusion, this study provides insights into the role of OSTα/β in preferential disposition of bile acids associated with hepatotoxicity, the impact of xenobiotics on OSTα/β-mediated bile acid transport, and the role of this transporter in SCHH and cholestatic DILI.

scholarly journals Chronic Activation of FXR in Transgenic Mice Caused Perinatal Toxicity and Sensitized Mice to Cholesterol Toxicity

2015 ◽  
Vol 29 (4) ◽  
pp. 571-582 ◽  
Author(s):  
Qiuqiong Cheng ◽  
Yuka Inaba ◽  
Peipei Lu ◽  
Meishu Xu ◽  
Jinhan He ◽  
...  
Keyword(s):  
Bile Acid ◽  
Transgenic Mice ◽  
Nuclear Receptor ◽  
Liver Toxicity ◽  
Acid Output ◽  
Farnesoid X Receptor ◽  
High Cholesterol Diet ◽  
Vitamin Supplement ◽  
Chronic Activation

Abstract The nuclear receptor farnesoid X receptor (FXR) (nuclear receptor subfamily 1, group H, member 4, or NR1H4) is highly expressed in the liver and intestine. Previous reports have suggested beneficial functions of FXR in the homeostasis of bile acids, lipids, and glucose, as well as in promoting liver regeneration and inhibiting carcinogenesis. To investigate the effect of chronic FXR activation in vivo, we generated transgenic mice that conditionally and tissue specifically express the activated form of FXR in the liver and intestine. Unexpectedly, the transgenic mice showed several intriguing phenotypes, including partial neonatal lethality, growth retardation, and spontaneous liver toxicity. The transgenic mice also displayed heightened sensitivity to a high-cholesterol diet-induced hepatotoxicity but resistance to the gallstone formation. The phenotypes were transgene specific, because they were abolished upon treatment with doxycycline to silence the transgene expression. The perinatal toxicity, which can be rescued by a maternal vitamin supplement, may have resulted from vitamin deficiency due to low biliary bile acid output as a consequence of inhibition of bile acid formation. Our results also suggested that the fibroblast growth factor-inducible immediate-early response protein 14 (Fn14), a member of the proinflammatory TNF family, is a FXR-responsive gene. However, the contribution of Fn14 induction in the perinatal toxic phenotype of the transgenic mice remains to be defined. Because FXR is being explored as a therapeutic target, our results suggested that a chronic activation of this nuclear receptor may have an unintended side effect especially during the perinatal stage.

scholarly journals Role of FXR in Bile Acid and Metabolic Homeostasis in NASH: Pathogenetic Concepts and Therapeutic Opportunities

2021 ◽  
Author(s):  
Richard Radun ◽  
Michael Trauner
Keyword(s):  
Liver Disease ◽  
Bile Acid ◽  
Enterohepatic Circulation ◽  
Therapeutic Potential ◽  
Farnesoid X Receptor ◽  
Metabolic Homeostasis ◽  
Nonalcoholic Fatty Liver ◽  
Metabolic Dysregulation ◽  
Attractive Therapeutic Target

AbstractNonalcoholic fatty liver disease (NAFLD) has become the most prevalent cause of liver disease, increasingly contributing to the burden of liver transplantation. In search for effective treatments, novel strategies addressing metabolic dysregulation, inflammation, and fibrosis are continuously emerging. Disturbed bile acid (BA) homeostasis and microcholestasis via hepatocellular retention of potentially toxic BAs may be an underappreciated factor in the pathogenesis of NAFLD and nonalcoholic steatohepatitis (NASH) as its progressive variant. In addition to their detergent properties, BAs act as signaling molecules regulating cellular homeostasis through interaction with BA receptors such as the Farnesoid X receptor (FXR). Apart from being a key regulator of BA metabolism and enterohepatic circulation, FXR regulates metabolic homeostasis and has immune-modulatory effects, making it an attractive therapeutic target in NAFLD/NASH. In this review, the molecular basis and therapeutic potential of targeting FXR with a specific focus on restoring BA and metabolic homeostasis in NASH is summarized.

Role of nuclear receptors and hepatocyte-enriched transcription factors for Ntcp repression in biliary obstruction in mouse liver

2005 ◽  
Vol 289 (5) ◽  
pp. G798-G805 ◽  
Author(s):  
Gernot Zollner ◽  
Martin Wagner ◽  
Peter Fickert ◽  
Andreas Geier ◽  
Andrea Fuchsbichler ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Bile Acid ◽  
Dna Binding ◽  
Nuclear Receptors ◽  
Farnesoid X Receptor ◽  
Acid Uptake ◽  
Mrna Levels ◽  
Uptake System ◽  
Duct Ligation

Expression of the main hepatic bile acid uptake system, the Na+-taurocholate cotransporter (Ntcp), is downregulated during cholestasis. Bile acid-induced, farnesoid X receptor (FXR)-mediated induction of the nuclear repressor short heterodimer partner (SHP) has been proposed as a key mechanism reducing Ntcp expression. However, the role of FXR and SHP or other nuclear receptors and hepatocyte-enriched transcription factors in mediating Ntcp repression in obstructive cholestasis is unclear. FXR knockout (FXR−/−) and wild-type (FXR+/+) mice were subjected to common bile duct ligation (CBDL). Cholic acid (CA)-fed and LPS-treated FXR−/− and FXR+/+ mice were studied for comparison. mRNA levels of Ntcp and SHP and nuclear protein levels of hepatocyte nuclear factor (HNF)-1α, HNF-3β, HNF-4α, retinoid X receptor (RXR)-α, and retinoic acid receptor (RAR)-α and their DNA binding were assessed. Hepatic cytokine mRNA levels were also measured. CBDL and CA led to Ntcp repression in FXR+/+, but not FXR−/−, mice, whereas LPS reduced Ntcp expression in both genotypes. CBDL and LPS but not CA induced cytokine expression and reduced levels of HNF-1α, HNF-3β, HNF-4α, RXRα, and RARα to similar extents in FXR+/+ and FXR−/−. DNA binding of these transactivators was unaffected by CA in FXR+/+ mice but was markedly reduced in FXR−/− mice. In conclusion, Ntcp repression by CBDL and CA is mediated by accumulating bile acids via FXR and does not depend on cytokines, whereas Ntcp repression by LPS is independent of FXR. Reduced levels of HNF-1α, RXRα, and RARα in CBDL FXR−/− mice and reduced DNA binding in CA-fed FXR−/− mice, despite unchanged Ntcp levels, indicate that these factors may have a minor role in regulation of mouse Ntcp during cholestasis.

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