scholarly journals Bile Acid Uptake Transporters as Targets for Therapy

2017 ◽  
Vol 35 (3) ◽  
pp. 251-258 ◽  
Author(s):  
Davor Slijepcevic ◽  
Stan F.J. van de Graaf
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Energy Homeostasis ◽  
Sodium Taurocholate ◽  
Hepatic Uptake ◽  
Farnesoid X Receptor ◽  
Acid Uptake ◽  
Bile Acid Uptake ◽  
Uptake Transporters ◽  
Conjugated Bile Acids

Background: Bile acids are potent signaling molecules that regulate glucose, lipid and energy homeostasis predominantly via the bile acid receptors farnesoid X receptor (FXR) and transmembrane G protein-coupled receptor 5 (TGR5). The sodium taurocholate cotransporting polypeptide (NTCP) and the apical sodium dependent bile acid transporter (ASBT) ensure an effective circulation of (conjugated) bile acids. The modulation of these transport proteins affects bile acid localization, dynamics and signaling. The NTCP-specific pharmacological inhibitor myrcludex B inhibits hepatic uptake of conjugated bile acids. Multiple ASBT-inhibitors are already in clinical trials to inhibit intestinal bile acid uptake. Here, we discuss current insights into the consequences of targeting bile acid uptake transporters on systemic and intestinal bile acid dynamics and discuss the possible therapeutic applications that evolve as a result.

scholarly journals ENDOCRINOLOGY IN PREGNANCY: Metabolic impact of bile acids in gestation

2021 ◽  
Vol 184 (3) ◽  
pp. R69-R83
Author(s):  
Hei Man Fan ◽  
Alice L Mitchell ◽  
Catherine Williamson
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Maternal Serum ◽  
Farnesoid X Receptor ◽  
Acid Uptake ◽  
Glucose And Lipid Metabolism ◽  
Bile Acid Uptake ◽  
In Pregnancy

Bile acids are lipid-solubilising molecules that also regulate metabolic processes. Farnesoid X receptor (FXR) and Takeda G-protein coupled receptor 5 (TGR5) are two bile acid receptors with key metabolic roles. FXR regulates bile acid synthesis in the liver and influences bile acid uptake in the intestine. TGR5 is mainly involved in regulation of signalling pathways in response to bile acid uptake in the gut and therefore prandial response. Both FXR and TGR5 have potential as therapeutic targets for disorders of glucose and/or lipid homeostasis. Gestation is also known to cause small increases in bile acid concentrations, but physiological hypercholanaemia of pregnancy is usually not sufficient to cause any clinically relevant effects. This review focuses on how gestation alters bile acid homeostasis, which can become pathological if the elevation of maternal serum bile acids is more marked than physiological hypercholanaemia, and on the influence of FXR and TGR5 function in pregnancy on glucose and lipid metabolism. This will be discussed with reference to two gestational disorders: intrahepatic cholestasis of pregnancy (ICP), a disease where bile acids are pathologically elevated, and gestational diabetes mellitus (GDM), characterised by hyperglycaemia during pregnancy.

scholarly journals The Human Na+-Taurocholate Cotransporting Polypeptide Gene Is Activated by Glucocorticoid Receptor and Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α, and Suppressed by Bile Acids via a Small Heterodimer Partner-Dependent Mechanism

2006 ◽  
Vol 20 (1) ◽  
pp. 65-79 ◽  
Author(s):  
Jyrki J. Eloranta ◽  
Diana Jung ◽  
Gerd A. Kullak-Ublick
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Human Hepatocytes ◽  
Farnesoid X Receptor ◽  
Peroxisome Proliferator ◽  
Acid Uptake ◽  
Peroxisome Proliferator Activated Receptor ◽  
Small Heterodimer Partner ◽  
Bile Acid Uptake ◽  
Sodium Dependent

Abstract Na+-taurocholate cotransporting polypeptide (NTCP) is the major bile acid uptake system in human hepatocytes. NTCP and the ileal transporter ASBT (apical sodium-dependent bile acid transporter) are two sodium-dependent transporters critical for the enterohepatic circulation of bile acids. The hASBT gene is known to be activated by the glucocorticoid receptor (GR). Here we show that GR also induces the endogenous hNTCP gene and transactivates the reporter-linked hNTCP promoter, in the presence of its ligand dexamethasone. Mutational analysis of the hNTCP promoter identified a functional GR response element, with which GR directly interacts within living cells. The GR/dexamethasone activation of endogenous hNTCP expression was suppressed by bile acids, in a manner dependent on the bile acid receptor farnesoid X receptor. Overexpression of the farnesoid X receptor-inducible transcriptional repressor small heterodimer partner also suppressed the GR/dexamethasone-activation of the hNTCP promoter. The peroxisome proliferator-activated receptor-γ coactivator-1α enhanced the GR/dexamethasone activation of the hNTCP promoter. In conclusion, the hNTCP promoter is activated by GR in a ligand-dependent manner, similarly to the hASBT promoter. Thus, glucocorticoids may coordinately regulate the major bile acid uptake systems in human liver and intestine. The GR/dexamethasone activation of the hNTCP promoter is counteracted by bile acids and small heterodimer partner, providing a negative feedback mechanism for bile acid uptake in human hepatocytes.

Interaction of bumetanide derivatives with hepatocellular bile acid uptake

1993 ◽  
Vol 265 (5) ◽  
pp. G942-G954
Author(s):  
E. Petzinger ◽  
W. Follmann ◽  
M. Blumrich ◽  
R. Schermuly ◽  
S. Schulz ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Model Building ◽  
Organic Anion ◽  
Rat Hepatocytes ◽  
Salt Transport ◽  
Acid Uptake ◽  
Ligand Interaction ◽  
Isolated Rat Hepatocytes ◽  
Bile Acid Uptake

The loop diuretic bumetanide is an organic monocarboxylic organic anion assumed to be transported into hepatocytes by a transport system for bile acids. The structural requirements of 22 bumetanide analogues were analyzed for an interaction with bile acid uptake into isolated rat hepatocytes. Whereas bumetanide inhibited the hepatocellular uptake of [14C]cholate to the same degree as its own uptake, derivatization altered affinity and specificity and yielded compounds that selectively inhibited either cholate or taurocholate uptake or uptake of both. No correlation was found between the diuretic potency of bumetanide derivatives, reflecting the affinity to the Na(+)-K(+)-Cl- cotransporter, and their affinity to hepatic bile salt transport. Computer-aided model building combined with the calculation of potential energy maps showed a strictly amphipathic charge separation in bumetanide analogues as in bile acids. Ranking bumetanide compounds by their mean inhibitory concentration values, inhibition constants, and their type of competition, we conclude that at least three binding domains in the proteins are essential for recognition by bile acid transporters, namely two hydrophobic and an anionic side, and that for the anionic binding region a carbonyl atom in the ligands as an electron donor group is sufficient for ligand interaction.

Mechanisms of Tauroursodeoxycholate-Mediated Hepatoprotection

2017 ◽  
Vol 35 (3) ◽  
pp. 224-231 ◽  
Author(s):  
Dieter Häussinger ◽  
Claus Kordes
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Molecular Mechanisms ◽  
Clinical Medicine ◽  
Basolateral Membrane ◽  
Sodium Taurocholate ◽  
Growth Factor Receptor ◽  
Adenosine Monophosphate ◽  
Farnesoid X Receptor ◽  
Integrin Subunit

Ursodeoxycholate and its taurine conjugate tauroursodeoxycholate (TUDC) promote choleresis by triggering the insertion of transport proteins for bile acids into the canalicular and basolateral membranes of hepatocytes. In addition, TUDC exerts hepatoprotective and anti-apoptotic effects, can counteract the action of toxic bile acids and reduce endoplasmic reticulum stress. TUDC can also initiate the differentiation of multipotent mesenchymal stem cells (MSC) including hepatic stellate cells and promote their development into hepatocyte-like cells. Although the hepatoprotective and choleretic action of TUDC is empirically used in clinical medicine since decades, the underlying molecular mechanisms remained largely unclear. Since TUDC has little or no potency to activate known bile acid receptors, such as farnesoid X receptor and transmembrane G protein-coupled bile acid receptor, other receptors must be involved in TUDC-mediated signaling. Recent research demonstrates that integrins serve as sensors for TUDC. After binding of TUDC to α5β1-integrin, the β1-integrin subunit becomes activated through a conformational change, thereby triggering integrin signaling with the downstream activation of focal adhesion kinase, c-Src, the epidermal growth factor receptor and activation of the mitogen-activated protein kinases, Erks and p38. These events trigger choleresis through a coordinated insertion of the sodium-taurocholate cotransporting polypeptide into the basolateral membrane and of the bile salt export pump into the canalicular membrane. In addition to its choleretic action, TUDC-induced integrin activation triggers a cyclic adenosine monophosphate-dependent protein kinase A activation in hepatocytes, which provides the basis for the anti-apoptotic effect of TUDC. On the other hand, the TUDC-induced stimulation of MSC differentiation appears not to be mediated by integrins. This article gives a brief overview about our work on the signaling network-mediating hepatoprotection by TUDC.

scholarly journals Intestinal bile acid receptors are key regulators of glucose homeostasis

2017 ◽  
Vol 76 (3) ◽  
pp. 192-202 ◽  
Author(s):  
Mohamed-Sami Trabelsi ◽  
Sophie Lestavel ◽  
Bart Staels ◽  
Xavier Collet
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Glucose Homeostasis ◽  
Energy Homeostasis ◽  
Acid Metabolism ◽  
Dietary Lipid ◽  
Farnesoid X Receptor ◽  
Bile Acid Metabolism ◽  
Metabolism Regulation ◽  
Bile Acid Receptors

In addition to their well-known function as dietary lipid detergents, bile acids have emerged as important signalling molecules that regulate energy homeostasis. Recent studies have highlighted that disrupted bile acid metabolism is associated with metabolism disorders such as dyslipidaemia, intestinal chronic inflammatory diseases and obesity. In particular, type 2 diabetes (T2D) is associated with quantitative and qualitative modifications in bile acid metabolism. Bile acids bind and modulate the activity of transmembrane and nuclear receptors (NR). Among these receptors, the G-protein-coupled bile acid receptor 1 (TGR5) and the NR farnesoid X receptor (FXR) are implicated in the regulation of bile acid, lipid, glucose and energy homeostasis. The role of these receptors in the intestine in energy metabolism regulation has been recently highlighted. More precisely, recent studies have shown that FXR is important for glucose homeostasis in particular in metabolic disorders such as T2D and obesity. This review highlights the growing importance of the bile acid receptors TGR5 and FXR in the intestine as key regulators of glucose metabolism and their potential as therapeutic targets.

scholarly journals Heterogeneous accumulation of fluorescent bile acids in primary rat hepatocytes does not correlate with their homogenous expression of ntcp

2011 ◽  
Vol 301 (1) ◽  
pp. G60-G68 ◽  
Author(s):  
John W. Murray ◽  
Amar J. Thosani ◽  
Pijun Wang ◽  
Allan W. Wolkoff
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Hela Cells ◽  
Organic Anion ◽  
Fluorescent Microscopy ◽  
Sodium Taurocholate ◽  
Rat Hepatocytes ◽  
Acid Uptake ◽  
Anion Transporter ◽  
Acid Accumulation

Sodium taurocholate-cotransporting polypeptide (ntcp) is considered to be a major determinant of bile acid uptake into hepatocytes. However, the regulation of ntcp and the degree that it participates in the accumulation of specific substrates are not well understood. We utilized fluorescent bile acid derivatives and direct quantitation of fluorescent microscopy images to examine the regulation of ntcp and its role in the cell-to-cell variability of fluorescent bile acid accumulation. Primary-cultured rat hepatocytes rapidly accumulated the fluorescent bile acids, chenodeoxycholylglycylamidofluorescein (CDCGamF), 7-β- nitrobenzoxadiazole 3-α hydroxy 5-β cholan-24-oic acid (NBD-CA), and cholyl-glycylamido-fluorescein (CGamF). However, in stably transfected HeLa cells, ntcp preferred CDCGamF, whereas the organic anion transporter, organic anion transporting polypeptide 1 (oatp1a1), preferred NBD-CA, and neither ntcp nor oatp1a1 showed strong accumulation of CGamF by these methods. Ntcp-mediated transport of CDCGamF was inhibited by taurocholate, cyclosporin, actin depolymerization, and an inhibitor of atypical PKC-ζ. The latter two agents altered the cellular distribution of ntcp as visualized in ntcp-green fluorescent protein-transfected cells. Although fluorescent bile acid accumulation was reproducible by the imaging assays, individual cells showed variable accumulation that was not attributable to changes in membrane permeability or cell viability. In HeLa cells, this was accounted for by variable levels of ntcp, whereas, in hepatocytes, ntcp expression was uniform, and low accumulation was seen in a large portion of cells despite the presence of ntcp. These studies indicate that single-cell imaging can provide insight into previously unrecognized details of anion transport in the complex environment of polarized hepatocytes.

scholarly journals Vertical Sleeve Gastrectomy Induces Enteroendocrine Cell Differentiation of Intestinal Stem Cells Through Farnesoid X Receptor Activation

2021 ◽  
Author(s):  
Ki-Suk Kim ◽  
Bailey C. E. Peck ◽  
Yu-Han Hung ◽  
Kieran Koch-Laskowski ◽  
Landon Wood ◽  
...  
Keyword(s):  
Sleeve Gastrectomy ◽  
Bile Acid ◽  
Bile Acids ◽  
Energy Homeostasis ◽  
Receptor Activation ◽  
Farnesoid X Receptor ◽  
Vertical Sleeve Gastrectomy ◽  
Gut Peptides ◽  
Intestinal Differentiation ◽  
Intestinal Organoids

AbstractVertical sleeve gastrectomy (VSG) is one of several bariatric procedures that substantially improves glycemia and energy homeostasis. Increased secretion of multiple gut peptides has been hypothesized to be a critical contributor to VSG’s potent effects to reduce body weight and improve glucose regulation. VSG results in an increase in the number of hormone-secreting enteroendocrine cells (EECs) in the intestinal epithelium, but whether this increase is via proliferation or differentiation of EECs and their subtypes remains unclear. Notably, the beneficial effects of VSG are lost in a mouse model lacking the bile acid nuclear receptor, farnesoid X receptor (FXR). FXR is a nuclear transcription factor that has been shown to regulate intestinal stem cell (ISC) function in cancer models, but whether it plays a role specifically in normal intestinal differentiation remains unknown. Therefore, we hypothesized that the VSG-induced increase in EECs is due to changes in intestinal differentiation driven by an increase in bile acid signaling through FXR. To test this, we performed VSG in mice that express eGFP in ISC/progenitor cells and performed RNAseq on GFP-positive cells sorted from the intestinal epithelia. We also assessed changes in EEC number (marked by GLP-1) in mouse intestinal organoids following treatment with bile acids and/or an FXR antagonist. RNA-seq revealed that FXR is expressed in ISCs and that VSG explicitly alters ISC expression of several genes that regulate intestinal secretory cell development, including EEC differentiation. Mouse intestinal organoids treated with bile acids increased GLP-1-positive cell numbers, whereas a potent FXR antagonist blocked this effect. Taken together, these data indicate that VSG drives ISC fate towards EEC differentiation through FXR signaling.

scholarly journals Fasting induces basolateral uptake transporters of the SLC family in the liver via HNF4α and PGC1α

2007 ◽  
Vol 293 (3) ◽  
pp. G585-G590 ◽  
Author(s):  
Christoph G. Dietrich ◽  
Ina V. Martin ◽  
Anne C. Porn ◽  
Sebastian Voigt ◽  
Carsten Gartung ◽  
...  
Keyword(s):  
Bile Acid ◽  
Mrna Expression ◽  
Binding Activity ◽  
Acid Uptake ◽  
Mobility Shift ◽  
Functional Studies ◽  
Bile Acid Uptake ◽  
Bile Acid Transporters ◽  
Uptake Transporters ◽  
Electrophoretic Mobility Shift Assays

Fasting induces numerous adaptive changes in metabolism by several central signaling pathways, the most important represented by the HNF4α/PGC-1α-pathway. Because HNF4α has been identified as central regulator of basolateral bile acid transporters and a previous study reports increased basolateral bile acid uptake into the liver during fasting, we hypothesized that HNF4α is involved in fasting-induced bile acid uptake via upregulation of basolateral bile acid transporters. In rats, mRNA of Ntcp, Oatp1, and Oatp2 were significantly increased after 48 h of fasting. Protein expression as determined by Western blot showed significant increases for all three transporters 72 h after the onset of fasting. Whereas binding activity of HNF1α in electrophoretic mobility shift assays remained unchanged, HNF4α binding activity to the Ntcp promoter was increased significantly. In line with this result, we found significantly increased mRNA expression of HNF4α and PGC-1α. Functional studies in HepG2 cells revealed an increased endogenous NTCP mRNA expression upon cotransfection with either HNF4α, PGC-1α, or a combination of both. We conclude that upregulation of the basolateral bile acid transporters Ntcp, Oatp1, and Oatp2 in fasted rats is mediated via the HNF4α/PGC-1α pathway.

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.

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