3β-Isoobeticholic acid efficiently activates the farnesoid X receptor (FXR) due to its epimerization to 3α-epimer by hepatic metabolism. Issue 202 (September 2020)

• Record Type: Journal Article
• Authors: Stefela, Alzbeta; Kaspar, Miroslav; Drastik, Martin; Holas, Ondrej; Hroch, Milos; Smutny, Tomas; Skoda, Josef; Hutníková, Miriama; Pandey, Amit V.; Micuda, Stanislav; Kudova, Eva; Pavek, Petr
• Is Part Of: Journal of steroid biochemistry and molecular biology. Issue 202(2020)
• Publication Date: 2020-09
• Subjects: BA bile acid -- BAR bile acid-activated receptor -- BSEP bile-salt export pump -- cAMP cyclic adenosine monophosphate -- CAR constitutive androstane receptor -- CDCA chenodeoxycholic acid -- CITCO 6-(4-Chlorophenyl)imidazo[2, 1-b][1, 3]thiazole-5-carbaldehyde-O-(3, 4-dichlorobenzyl)oxime -- CRE cAMP response element-binding -- CYP7A1 cholesterol 7α-hydroxylase -- CYP3A4 cytochrome P450 3A4 -- DCA deoxycholic acid -- FSK forskolin -- FXR farnesoid X receptor -- GPBAR1 G protein-coupled bile acid receptor 1 -- HSD3B7 hydroxy-delta-5-steroid dehydrogenase, syn. 3β-hydroxy-Δ5-C27-steroid oxidoreductase -- LBD ligand-binding domain -- LCA lithocholic acid -- LC–MS liquid chromatography–mass spectrometry -- LDL low-density lipoprotein -- NASH non-alcoholic steatohepatitis -- NTCP Na + taurocholate cotransport peptide -- OCA obeticholic acid -- PXR pregnane X receptor -- RT-qPCR real-time quantitative polymerase chain reaction -- SHP small heterodimer partner -- UDCA ursodeoxycholic acid -- TLCA taurolithocholic acid -- TR-FRET time-resolved fluorescence energy transfer -- VDR vitamin D receptor; Nuclear receptors -- Bile acids -- Pharmacokinetics -- Gene regulation -- Metabolism; Steroid hormones -- Periodicals; Biochemistry -- Periodicals; Hormones -- Periodicals; Molecular Biology -- Periodicals; Hormones stéroïdes -- Périodiques; Steroid hormones; Periodicals; 572.579
• DOI: 10.1016/j.jsbmb.2020.105702
• Languages: English
• ISSNs: 0960-0760

Abstract

Graphical abstract: Highlights: 3β-IsoOCA is an efficient FXR activator due to epimerization to OCA in the hepatic cells. 3, 7-DehydroOCA is a novel potent GPBAR1 ligand. Oxidation or epimerization on C3/C7 positions in the OCA scaffold abrogate affinity to FXR or GPBAR1. 6-Ethylidene in the OCA scaffold abrogates affinity to FXR and GPBAR1. Abstract: Bile acids (BAs) are important signaling molecules acting via the farnesoid X nuclear receptor (FXR) and the membrane G protein-coupled bile acid receptor 1 (GPBAR1). Besides deconjugation of BAs, the oxidoreductive enzymes of colonic bacteria and hepatocytes enable the conversion of BAs into their epimers or dehydrogenated forms. Obeticholic acid (OCA) is the first-in-class BA-derived FXR agonist approved for the treatment of primary biliary cholangitis. Herein, a library of OCA derivatives, including 7-keto, 6-ethylidene derivatives and 3β-epimers, was synthetized and investigated in terms of interactions with FXR and GPBAR1 in transaction assays and evaluated for FXR target genes expression in human hepatocytes and C57BL/6 mice. The derivatives were further subjected to cell-free analysis employing in silico molecular docking and a TR-FRET assay. The conversion of the 3βhydroxy epimer and its pharmacokinetics in mice were studied using LC–MS. We found that only the 3β-hydroxy epimer of OCA (3β-isoOCA) possesses significant activity to FXR in hepatic cells and mice. However, in a cell-free assay, 3β-isoOCA had about 9-times lower affinity to FXR than did OCA. We observed that 3β-isoOCA readily epimerizes to OCA in hepatocytes and murine liver. This conversion was significantly inhibited by the hydroxy-Δ 5 -steroid dehydrogenase inhibitor trilostane. In addition, we found that 3, 7-dehydroobeticholic acid is a potent GPBAR1 agonist. We conclude that 3β-isoOCA significantly activates FXR due to its epimerization to the more active OCA by hepatic metabolism. Other modifications as well as epimerization on the C3/C7 positions and the introduction of 6-ethylidene in the CDCA scaffold abrogate FXR agonism and alleviate GPBAR1 activation.