Abstract 402: Post-transcriptional Regulation of Bile Acid Metabolism by the RNA binding protein ZFP36L1

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Elizabeth Tarling ◽  
Joan Cheng ◽  
Angela Cheng ◽  
Pauline Morand ◽  
Bethan Clifford ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Acid Metabolism ◽  
Rna Binding ◽  
Binding Protein ◽  
Plasma Cholesterol ◽  
Rna Binding Protein ◽  
Lipid Absorption ◽  
Bile Acid Metabolism ◽  
Mrna Levels

Bile acids are detergents and important signaling molecules that activate the nuclear receptor FXR to control key metabolic processes, including feedback mechanisms to maintain bile acid homeostasis. Activation of FXR decreases the mRNA levels of several bile acid synthetic genes, including the rate-limiting enzyme Cyp7a1 . Here we show that Cyp7a1 mRNA levels are very rapidly reduced following FXR activation, indicative of a post-transcriptional mechanism. We identify the RNA binding protein Zfp36l1 as an FXR target gene and show that hepatic overexpression of ZFP36L1 in mice decreases Cyp7a1 mRNA levels. In contrast, Zfp36l1 L -KO mice have increased levels of Cyp7a1 mRNA and biliary bile acids as well as reduced plasma cholesterol levels. Zfp36l1 L -KO mice fed a Western diet have reduced diet-induced obesity and steatosis, likely due to impaired lipid absorption, consistent with increased Cyp7a1 levels. Thus, the ZFP36L1-dependent regulation of bile acid metabolism is an important metabolic contributor of dyslipidemia, obesity and hepatosteatosis.

scholarly journals RNA-binding protein ZFP36L1 maintains posttranscriptional regulation of bile acid metabolism

2017 ◽  
Vol 127 (10) ◽  
pp. 3741-3754 ◽  
Author(s):  
Elizabeth J. Tarling ◽  
Bethan L. Clifford ◽  
Joan Cheng ◽  
Pauline Morand ◽  
Angela Cheng ◽  
...  
Keyword(s):  
Bile Acid ◽  
Posttranscriptional Regulation ◽  
Acid Metabolism ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Bile Acid Metabolism

Abstract 49: The Transcriptional Repressor MafG Regulates Cholesterol Catabolism

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Thomas Q de Aguiar Vallim ◽  
Elizabeth J Tarling ◽  
Hannah Ahn ◽  
Lee R Hagey ◽  
Casey E Romanoski ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Acid Metabolism ◽  
Metabolic Diseases ◽  
Cholesterol Metabolism ◽  
Transcriptional Repressor ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Bile Acid Metabolism ◽  
Biliary Bile Acid

Elevated circulating cholesterol levels is a major risk factor for cardiovascular diseases (CVD), and therefore understanding pathways that affect cholesterol metabolism are important for potential treatment of CVD. The major route for cholesterol excretion is through its catabolism to bile acids. Specific bile acids are also potent signaling molecules that modulate metabolic pathways affecting lipid, glucose and bile acid homeostasis. Bile acids are synthesized from cholesterol in the liver, and the key enzymes involved in bile acid synthesis ( Cyp7a1 , Cyp8b1 ) are regulated transcriptionally by the nuclear receptor FXR. We have identified an FXR-regulated pathway upstream of a transcriptional repressor that controls multiple bile acid metabolism genes. We identify MafG as an FXR target gene and show that hepatic MAFG overexpression represses genes of the bile acid synthetic pathway, and modifies the biliary bile acid composition. In contrast, MafG loss-of-function studies cause de-repression of the bile acid genes with concordant changes in biliary bile acid levels. Finally, we identify functional MafG response elements in bile acid metabolism genes using ChIP-Seq analysis. Our studies identify a molecular mechanism for the complex feedback regulation of bile acid synthesis controlled by FXR. The identification of this pathway will likely have important implications in metabolic diseases.

Bile Acids: The Good, the Bad, and the Ugly

Physiology ◽  
1999 ◽  
Vol 14 (1) ◽  
pp. 24-29 ◽  
Author(s):  
Alan F. Hofmann
Keyword(s):  
Bile Acids ◽  
Enterohepatic Circulation ◽  
Cholesterol Metabolism ◽  
Plasma Cholesterol ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Lipid Absorption ◽  
Bile Acid Metabolism ◽  
Cholesterol Levels ◽  
Density Lipoprotein Receptor

Bile acids, amphipathic end products of cholesterol metabolism, are “good” in the infant because they enhance lipid absorption and thereby promote growth. Bile acids also induce bile flow and biliary lipid secretion. The enterohepatic circulation of bile acids is “bad” in the adult because it downregulates hepatocyte low-density lipoprotein receptor activity and thereby elevates plasma cholesterol levels. Defects in bile acid metabolism such as impaired biosynthesis or transport are “ugly” because they cause morbidity and death. New approaches for treating these defects are being developed.

scholarly journals Identification of bile acids in the serum and urine in cholestasis. Evidence for 6α-hydroxylation of bile acids in man

1976 ◽  
Vol 154 (2) ◽  
pp. 507-516 ◽  
Author(s):  
J A. Summerfield ◽  
B H. Billing ◽  
C H. L. Shackleton
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Acid Metabolism ◽  
Gas Chromatography Mass Spectrometry ◽  
Acid Mixture ◽  
Bile Acid Metabolism ◽  
Hyodeoxycholic Acid ◽  
Normal Man ◽  
Hyocholic Acid ◽  
Sulphate Conjugate

In this qualitative study of the pattern of bile acid excretion in cholestasis, methods are described for the isolation of bile acids from large volumes of urine and plasma. The bile acids were subjected to a group separation and identified by combined gas chromatography-mass spectrometry. The techniques were developed to allow identification of the minor components of the bile acid mixture. Four bile acids that have not previously been described in human urine and plasma were detected, namely 3β, 7α-dihydroxy-5β-cholan-24-oic acid, 3α, 6α-dihydroxy-5β-cholan-24-oic acid (hyodeoxycholic acid), 3α, 6α, 7α-trihydroxy-5β-cholan-24-oic acid (hyocholic acid) and 3α, 7β, 12α-trihydroxy-5β-cholan-24-oic acid. In addition three C27 steroids were found; 26-hydroxycholesterol and a trihydroxy cholestane, probably 5 β-cholestane-3α, 7α, 26-triol were found in the sulphate fraction of plasma and urine. In the plasma sample, a sulphate conjugate of 24-hydroxycholesterol was found. The presence of these compounds probably reflects the existence of further pathways for bile acid metabolism. It is not yet known whether this is a consequence of the cholestasis or whether they are also present in normal man, at much lower concentrations.

scholarly journals Inulin Supplementation Disturbs Hepatic Cholesterol and Bile Acid Metabolism Independent from Housing Temperature

Nutrients ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 3200
Author(s):  
Mira J. Pauly ◽  
Julia K. Rohde ◽  
Clara John ◽  
Ioannis Evangelakos ◽  
Anja Christina Koop ◽  
...  
Keyword(s):  
Bile Acid ◽  
Acid Metabolism ◽  
Plasma Cholesterol ◽  
Cold Treatment ◽  
Short Chain Fatty Acids ◽  
Liver Cholesterol ◽  
Bile Acid Metabolism ◽  
Short Term ◽  
Hepatic Bile ◽  
Brown Adipose

Dietary fibers are fermented by gut bacteria into the major short chain fatty acids (SCFAs) acetate, propionate, and butyrate. Generally, fiber-rich diets are believed to improve metabolic health. However, recent studies suggest that long-term supplementation with fibers causes changes in hepatic bile acid metabolism, hepatocyte damage, and hepatocellular cancer in dysbiotic mice. Alterations in hepatic bile acid metabolism have also been reported after cold-induced activation of brown adipose tissue. Here, we aim to investigate the effects of short-term dietary inulin supplementation on liver cholesterol and bile acid metabolism in control and cold housed specific pathogen free wild type (WT) mice. We found that short-term inulin feeding lowered plasma cholesterol levels and provoked cholestasis and mild liver damage in WT mice. Of note, inulin feeding caused marked perturbations in bile acid metabolism, which were aggravated by cold treatment. Our studies indicate that even relatively short periods of inulin consumption in mice with an intact gut microbiome have detrimental effects on liver metabolism and function.

scholarly journals Aryl Hydrocarbon Receptor (AhR) Activation by 2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) Dose-Dependently Shifts the Gut Microbiome Consistent with the Progression of Non-Alcoholic Fatty Liver Disease

2021 ◽  
Vol 22 (22) ◽  
pp. 12431
Author(s):  
Russell R. Fling ◽  
Timothy R. Zacharewski
Keyword(s):  
Liver Disease ◽  
Bile Acid ◽  
Fatty Liver ◽  
Bile Acids ◽  
Fatty Liver Disease ◽  
Acid Metabolism ◽  
Bile Acid Metabolism ◽  
Alcoholic Fatty Liver ◽  
Dose Dependent ◽  
Alcoholic Fatty Liver Disease

Gut dysbiosis with disrupted enterohepatic bile acid metabolism is commonly associated with non-alcoholic fatty liver disease (NAFLD) and recapitulated in a NAFLD-phenotype elicited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in mice. TCDD induces hepatic fat accumulation and increases levels of secondary bile acids, including taurolithocholic acid and deoxycholic acid (microbial modified bile acids involved in host bile acid regulation signaling pathways). To investigate the effects of TCDD on the gut microbiota, the cecum contents of male C57BL/6 mice orally gavaged with sesame oil vehicle or 0.3, 3, or 30 µg/kg TCDD were examined using shotgun metagenomic sequencing. Taxonomic analysis identified dose-dependent increases in Lactobacillus species (i.e., Lactobacillus reuteri). Increased species were also associated with dose-dependent increases in bile salt hydrolase sequences, responsible for deconjugation reactions in secondary bile acid metabolism. Increased L. reuteri levels were further associated with mevalonate-dependent isopentenyl diphosphate (IPP) biosynthesis and o-succinylbenzoate synthase, a menaquinone biosynthesis associated gene. Analysis of the gut microbiomes from cirrhosis patients identified an increased abundance of genes from the mevalonate-dependent IPP biosynthesis as well as several other menaquinone biosynthesis genes, including o-succinylbenzoate synthase. These results extend the association of lactobacilli with the AhR/intestinal axis in NAFLD progression and highlight the similarities between TCDD-elicited phenotypes in mice to human NAFLD.

scholarly journals Bile acid metabolism is altered in multiple sclerosis and supplementation ameliorates neuroinflammation

2019 ◽  
Author(s):  
Pavan Bhargava ◽  
Leah Mische ◽  
Matthew D. Smith ◽  
Emily Harrington ◽  
Kathryn C Fitzgerald ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Bile Acid ◽  
Bile Acids ◽  
Acid Metabolism ◽  
White Matter Lesions ◽  
The Body ◽  
Bile Acid Metabolism ◽  
Dependent Manner ◽  
Microglial Polarization

AbstractMultiple sclerosis (MS) is an inflammatory demyelinating disorder of the CNS. Bile acids are cholesterol metabolites that can signal through receptors on cells throughout the body, including the CNS and immune system. Whether bile acid metabolism is abnormal in MS is unknown. Using global and targeted metabolomic profiling, we identified lower levels of circulating bile acid metabolites in multiple cohorts of adult and pediatric MS patients compared to controls. In white matter lesions from MS brain tissue, we noted the presence of bile acid receptors on immune and glial cells. To mechanistically examine the implications of lower levels of bile acids in MS, we studied the in vitro effects of an endogenous bile acid – tauroursodeoxycholic acid (TUDCA) on astrocyte and microglial polarization. TUDCA prevented neurotoxic (A1) polarization of astrocytes and pro-inflammatory polarization of microglia in a dose-dependent manner. TUDCA supplementation in experimental autoimmune encephalomyelitis reduced severity of disease, based on behavioral and pathological measures. We demonstrate that bile acid metabolism is altered in MS; bile acid supplementation prevents polarization of astrocytes and microglia to neurotoxic phenotypes and ameliorates neuropathology in an animal model of MS. These findings identify dysregulated bile acid metabolism as a potential therapeutic target in MS.

scholarly journals Effects of Rhein on Bile Acid Homeostasis in Rats

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zhong Xian ◽  
Jingzhuo Tian ◽  
Lianmei Wang ◽  
Yushi Zhang ◽  
Jiayin Han ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Acid Metabolism ◽  
Farnesoid X Receptor ◽  
Bile Acid Metabolism ◽  
Edible Plant ◽  
Clinical Dose ◽  
Acid Accumulation ◽  
Liver And Kidney ◽  
Hepatic Transporters

Rhein, the active ingredient of rhubarb, a medicinal and edible plant, is widely used in clinical practice. However, the effects of repeated intake of rhein on liver function and bile acid metabolism are rarely reported. In this work, we investigated the alterations of 14 bile acids and hepatic transporters after rats were administered with rhein for 5 weeks. There was no obvious injury to the liver and kidney, and there were no significant changes in biochemical indicators. However, 1,000 mg/kg rhein increased the liver total bile acid (TBA) levels, especially taurine-conjugated bile acids (t-CBAs), inhibited the expression of farnesoid X receptor (FXR), small heterodimer partner (SHP), and bile salt export pump (BSEP) mRNA, and upregulated the expression of (cholesterol 7α-hydroxylase) CYP7A1 mRNA. Rhein close to the clinical dose (10 mg/kg and 30 mg/kg) reduced the amounts of TBAs, especially unconjugated bile acids (UCBAs), and elevated the expression of FXR and multidrug resistance-associated protein 3 (Mrp3) mRNA. These results denote that rhein is relatively safe to use at a reasonable dose and timing. 30 mg/kg rhein may promote bile acid transport and reduce bile acid accumulation by upregulating the expression of FXR mRNA and Mrp3 mRNA, potentially resulting in the decrease in serum UBCAs.

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