Clinical Application of Transcriptional Activators of Bile Salt Transporters

Molecular Aspects of Medicine 37 (2014) 57–76

Contents lists available at ScienceDirect

Molecular Aspects of Medicine

journal homepage: www.elsevier.com/locate/mam

Review Clinical application of transcriptional activators of bile salt transporters q ⇑ Anna Baghdasaryan a,b, Peter Chiba c, Michael Trauner a, a Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Austria b Laboratory of Experimental and Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, Austria c Institute of Medical Chemistry, Medical University of Vienna, Austria article info abstract

Article history: Hepatobiliary bile salt (BS) transporters are critical determinants of BS homeostasis con- Available online 12 December 2013 trolling intracellular concentrations of BSs and their enterohepatic circulation. Genetic or acquired dysfunction of specific transport systems causes intrahepatic and systemic reten- Keywords: tion of potentially cytotoxic BSs, which, in high concentrations, may disturb integrity of cell Nuclear receptors membranes and subcellular organelles resulting in cell death, inflammation and fibrosis. ATB-binding cassette transporters Transcriptional regulation of canalicular BS efflux through bile salt export pump (BSEP), Cholestasis basolateral elimination through organic solute transporters alpha and beta (OSTa/OSTb) + Chemical compounds studied in this article: as well as inhibition of hepatocellular BS uptake through basolateral Na -taurocholate 24-norUDCA (PubChem CID: 192254) cotransporting polypeptide (NTCP) represent critical steps in protection from hepatocellu- Bezafibrate (PubChem CID: 39042) lar BS overload and can be targeted therapeutically. In this article, we review the potential Budesonide (PubChem CID: 5281004) clinical implications of the major BS transporters BSEP, OSTa/OSTb and NTCP in the

Abbreviations: ABC, ATP-binding cassette; AE2 (SLC4A2), anion exchanger 2; ALT, alanine aminotransferase; AMPK, AMP-activated protein kinase; ALP, alkaline phosphatase; ASBT (SLC10A2), apical sodium-dependent bile acid transporter; ASCOM, activating signal cointegrator-2-containing complex; BCRP (ABCG2), breast cancer resistance protein; BRIC2, benign recurrent intrahepatic cholestasis type 2; BS, bile salt; BSEP (ABCB11), bile salt export pump; CA, cholic acid; cAMP, cyclic adenosine monophosphate; CARM1, co-activator-associated arginine methyltransferase 1; CBDL, common bile duct ligation; CCl4, carbone tetrachloride; CDCA, chenodeoxycholic acid; CtBP, C-terminal binding protein; DCA, deoxycholic acid; DILI, drug-induced liver injury; GCA, glycocholic acid; GGT, gamma-glutamyl transpeptidase; GR (NR3C1), glucocorticoid receptor; GRE, glucocorticoid response element; HNF1a, hepatocyte nuclear factor 1 alpha; HNF4a, hepatocyte nuclear factor 4 alpha; ICP, intrahepatic cholestasis of pregnancy; IL-1b, interleukin-1 beta; IL-6, interleukin 6; IR-1, inverse repeat 1; FGF19/FGF15, ﬁbroblast growth factor 19/15; FXR, farnesoid X receptor (NR1H4); FXRE, FXR response element; JNK, c-Jun N-terminal kinase; LCA, litocholic acid; LRH1 (NR5A2), liver receptor homologue 1; LPS, lipopolysaccharide; LXR (NR1H3), liver X receptor; MAF, musculo-aponeurotic ﬁbrosacroma; MARE, MAF recognition element; MCL-1, myeloid cell leukemia factor 1; MDR1 (ABCB1), multidrug resistance protein 1; MDR2 (ABCB4), multidrug resistance protein 2; MRP2 (ABCC2), multidrug resistance-associated protein 2; MRP3 (ABCC3), multidrug resistance-associated protein 3; MRP4 (ABCC4), multidrug resistance-associated protein 4; NDRG2, NMYC downstrean-regulated gene 2; NF-jB, nuclear factor kappa-B; NRF2, nuclear factor erythroid 2-related factor 2; NTCP (SLC10A1), Na+-taurocholate cotransporting polypeptide solute carrier family 10 member 1; OATP, organic anion transporting polypeptide; OCA, obeticholic acid; OSTa/OSTb (SLC51A/SLC51B), organic solute transporter alpha/beta; PBC, primary biliary cirrhosis; PFIC2, progressive familial intrahepatic cholestasis type 2; PGC-1a, peroxisome proliferator-activated receptor gamma coactivator-1 alpha; PL, phospholipid; PPARa (NR1C1), peroxisome proliferator-activated receptor alpha; PPARc (NR1C3), peroxisome proliferator-activated receptor gamma; PSC, primary sclerosing cholangitis; PXR (NR1I2), pregnane X receptor; RARa (NR1B1), retinoic acid receptor; RXRa (NR2B1), retinoid X receptor; SHP (NR0B2), short heterodimer partner; SRC2, steroid receptor co-activator 2; SREBP1, sterol regulatory element-binding protein 1; STAT-5, signal transducer and activator of transcription 5; TaMCA, a-tauromuricholic acid; TbMCA, b-tauromuricholic acid; TCA, taurocholic acid; TCDCA, taurochenodeoxycholic acid; TUDCA, tauroursodeoxycholic acid; TGR5, G protein coupled bile acid receptor; TNF-a, tumor necrosis factor alpha; TPN, total parenteral nutrition; UDCA, ursodeoxycholic acid; VDR (NR1I1), vitamin D receptor; VPAC-1, vasoactive intestinal polypeptide activated receptor. q This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited. ⇑ Corresponding author. Address: Gastroenterology and Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria. Tel.: +43 1 40 4004741; fax: +43 1 40 4004735. E-mail address: [email protected] (M. Trauner). http://dx.doi.org/10.1016/j.mam.2013.12.001 0098-2997/Ó 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). 58 A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76

Fenoﬁbrate (PubChem CID: 3339) pathogenesis of hereditary and acquired cholestatic syndromes, provide an overview on FXR-450/WAY-362450 (PubChem CID: transcriptional control of these transporters by the key regulatory nuclear receptors and 10026128) discuss the potential therapeutic role of novel transcriptional activators of BS transporters GW4064 (PubChem CID: 9893571) in cholestasis. Ursodeoxycholic acid/UDCA/ursodiol Ó 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY- (PubChem CID: 31401) Obeticholic acid/INT-747/6alpha- NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). ethylchenodeoxycholic acid (PubChem CID: 447715) Phenobarbital (PubChem CID: 4763) Rifampicin (PubChem CID: 5381226)

Contents

1. Introduction ...... 58 2. Functional role of BSEP in health and disease ...... 58 3. Transcriptional regulation of BSEP ...... 59 4. Functional role of OSTa/OSTb in health and disease ...... 60 5. Transcriptional regulation of OSTa/OSTb ...... 61 6. Functional role of NTCP in health and disease ...... 61 7. Transcriptional regulation of NTCP ...... 62 8. Novel therapeutic strategies targeting transcription factors in cholestasis ...... 63 8.1. Ursodeoxycholic acid and derivatives ...... 63 8.2. Therapeutic potential of FXR activators ...... 64 8.3. Therapeutic potential of CAR and PXR ...... 65 8.4. Therapeutic potential of GR, PPARa, PPARc andVDR...... 66 9. Conclusions...... 67 Funding ...... 67 References ...... 67

1. Introduction

Cholestatic liver injury comprises a wide range of genetic or acquired disorders of bile formation and/or flow ultimately resulting in intrahepatic and systemic accumulation of bile salts (BSs) (Lindblad et al., 1977; Setchell et al., 1997). Primary or secondary dysfunctions of specific hepatocellular transport systems as well as mechanical obstruction/destruction of the bile duct system are central mechanisms causing impaired elimination of biliary constituents. Elevated levels of BSs may cause liver damage due to their lipid solubilizing, proinflammatory and proapoptotic properties (Allen et al., 2010; Faubion et al., 1999; Graf et al., 2002; Guicciardi and Gores, 2002; Krahenbuhl et al., 1994; Reinehr et al., 2003). Since intracellular BS con- tent is regulated by complex mechanisms involving BS uptake, synthesis, detoxification and export, transcriptional stimulation or inhibition of specific transport mechanisms may be critical in limiting intrahepatic retention of BSs and hepatocyte damage. The canalicular BS export pump (BSEP), basolateral efflux transporter organic solute transporters alpha and beta (OSTa/OSTb) as well as the BS uptake system Na+-taurocholate cotransporting polypeptide (NTCP) are the major regulators of intracellular BS load and have emerged as promising drug targets in cholestasis.

2. Functional role of BSEP in health and disease

Canalicular excretion of BSs constitutes the rate-limiting step in hepatic BS excretion and represents the driving force for their enterohepatic circulation (Stieger and Beuers, 2011). BSEP (ABCB11), previously also known as sister of p-glycoprotein (sPgp) is a member of the canalicular ATP-binding cassette (ABC) transporter superfamily and represents the major canalicular BS export system (Childs et al., 1995; Gerloff et al., 1998; Nishida et al., 1991; Stieger and Beuers, 2011). Conjugated monovalent BSs are the major substrate for BSEP (Byrne et al., 2002; Gerloff et al., 1998; Hayashi et al., 2005; Noe et al., 2002; Stieger et al., 2000), among which taurochenodeoxycholic acid (TCDCA) is the preferred substrate followed by taurocholic acid (TCA), tauroursodeoxycholic acid (TUDCA) and glycocholic acid (GCA) (Noe et al., 2002). Various BSEP mutations differently impact on transporter activity leading to a wide variety of clinical manifestations in humans (Ho et al., 2010; Kagawa et al., 2008). Complete loss of function BSEP mutations manifest as severe cholestasis in progressive familial intrahepatic cholestasis type 2 (PFIC2) (Jansen et al., 1999; Strautnieks et al., 1998, 2008) and patients carry a considerable risk for development of hepatobiliary malignancies (Knisely and Portmann, 2006; Knisely et al., 2006; Scheimann et al., 2007; Sheridan et al., 2012; Strautnieks et al., 2008) likely due to persistent cell injury by elevated concentrations of intracellular BSs and impairment of cell repair mechanisms (Knisely et al., 2006; Palmeira and Rolo, 2004; Sokol et al., 2006; Souza et al., 2008). In contrast, BSEP variants with mildly impaired transporter function manifest in form of benign recurrent intrahepatic cholestasis type 2 (BRIC2) (Kubitz et al., 2006; van Mil et al., 2004) and may have a pathogenetic role in A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 59 acquired cholestatic syndromes such as intrahepatic cholestasis of pregnancy (ICP) and drug-induced liver injury (DILI) (Dixon et al., 2009; Eloranta et al., 2003; Keitel et al., 2006; Kubitz et al., 2006; Lang et al., 2007; Meier et al., 2008; Pauli-Magnus et al., 2004; van Mil et al., 2004). Although BSEP is critical for the maintenance of biliary BS excretion and protection against intrahepatic BS accumulation in humans, BSEP deficiency in mice causes only mild and non-progressive cholestasis with 30% preserved biliary BS output (mainly as tetra-hydroxylated BSs). It is important to note that in addition to BSEP, canalicular transporters such as the multidrug resistance protein 1 (MDR1/ABCB1), the multidrug resistance-associated protein 2 (MRP2/ABCC2) and the breast cancer resistance protein (BCRP/ABCG2) may also mediate canalicular export of sul- fated bivalent and unusual tetra-hydroxylated BSs (Akita et al., 2001; Janvilisri et al., 2005; Keppler et al., 1997; Lam et al., 2005; Mennone et al., 2010; Wang et al., 2001a) accounting for partially preserved biliary BS elimination in rodents. In addition to genetic BSEP variants, BSEP represents a vulnerable target for inhibition by various endogenous hormones/ metabolites, inflammation or drugs resulting in acquired cholestasis such as ICP, DILI, sepsis/endotoxin-induced cholestasis and cholestasis caused by total parenteral nutrition (TPN). The pathogenesis of ICP is complex, but hypersensitivity to female hormones or their metabolites is likely to be involved (Arrese et al., 2008). Inhibition of BSEP gene transcription by b-estradiol or inhibition of its functional activity through trans-inhibition and internalization by the estrogen metabolite estradiol-17b-glucuronide (Crocenzi et al., 2003; Gerloff et al., 2002; Stieger et al., 2000) are important mechanisms predisposing to estrogen-induced cholestasis (Barth et al., 2003; Yamamoto et al., 2006). Apart from female hormones, drugs such as cyclosporine, glibenclamide, rifamycin SV, rifampicin, indomethacin and bosentan (Byrne et al., 2002; Fattinger et al., 2001; Fouassier et al., 2002; Morgan et al., 2010; Noe et al., 2002; Ogimura et al., 2011; Stieger, 2010; Stieger et al., 2000)or constituents of TPN solutions (Li et al., 2012; Nishimura et al., 2005) may also inhibit BSEP-mediated BS export through either competitive inhibition (Stieger et al., 2000) or through mechanisms involving MRP2-dependent stimulation of BS-independent bile flow (Fouassier et al., 2002). Notably, genetic or acquired BSEP dysfunction is also likely to predispose to biliary cholesterol precipitation, since biliary BSs are essential for cholesterol solubilization in bile. This may explain the high prevalence of gallstone disease (32%) in PFIC2 patients (Pawlikowska et al., 2010). In support of this hypothesis, patients with cholesterol gallstones show low expression of the BSEP upstream regulator farnesoid X receptor (FXR/NR1H4)(Bertolotti et al., 2006) and its coactivator peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1a (Zhang et al., 2004), whereas FXR activation prevents gallstone formation in mice (Moschetta et al., 2004). In addition, reduced efflux of biliary BSs may lead to malabsorption of fat and fat-soluble vitamins and subsequently impair whole body energy homeostasis. Indeed, children with PFIC2 developed severe steatorrhoea (Walkowiak et al., 2006), whereas BSEP overexpression increased dietary cholesterol and fatty acid absorption and promoted development of diet-induced obesity in mice (Henkel et al., 2011; Wang et al., 2010). Finally, altered biliary BS elimination may have multiple extrahepatic implications, which may be attributed to the emerging key role of BSs in lipid, glucose and energy homeostasis (Thomas et al., 2009; Thomas et al., 2008; Wang et al., 2003a; Watanabe et al., 2006). Taken together, targeting mechanisms promoting BSEP-mediated BS export can be expected to have beneficial effects in cholestatic liver injury and its extrahepatic complications.

3. Transcriptional regulation of BSEP

Regulation of BSEP-mediated BS efflux is complex and involves transcriptional as well as posttranscriptional mechanisms (the latter discussed in chapter by J.L. Boyer). The nuclear BS receptor FXR acts as the major stimulator of BSEP transcription in humans, mice and rats through its heterodimerization with the retinoid X receptor alpha (RXRa) and binding to the FXR response element (FXRE), inverse repeat 1 (IR-1), in the BSEP promoter (Ananthanarayanan et al., 2001; Gerloff et al., 2002; Plass et al., 2002). BS-mediated BSEP expression is likely to be influenced by intracellular BS flux rather than steady state concentrations (Wolters et al., 2002) and differs dependent on the ability of endogenous BSs to activate FXR. Notably, chenodeoxycholic acid (CDCA), deoxycholic acid (DCA) and cholic acid (CA) are strong FXR activators (Makishima et al., 1999; Parks et al., 1999; Wang et al., 1999), whereas the less potent FXR activator litocholic acid (LCA) even inhibited FXR-mediated BSEP transactivation by endogenous and synthetic FXR ligands (CDCA and GW4064 respectively) (Yu et al., 2002). Importantly, murine-specific primary BSs a- and b-tauromuricholic acid (TaMCA and TbMCA) were also identified as FXR antagonists and may be responsible for lower expression of FXR target genes in ileum of germ-free mice (Sayin et al., 2013). Furthermore, TbMCA biotransformation by gut microbiota may significantly influence BS synthesis as well as transport through mitigation of TbMCA-mediated FXR inhibition in gut (Sayin et al., 2013). Recent studies identified the role of several nuclear receptor co-activating proteins as important mediators of FXR- mediated BSEP transcription. In particular, the key regulator of energy homeostasis PGC-1a and components of the activating signal cointegrator-2-containing complex (ASCOM) interact with FXR to enhance FXR-dependent BSEP expression in a ligand-dependent manner (Ananthanarayanan et al., 2011; Kanaya et al., 2004; Savkur et al., 2005). Importantly, recruitment of the ASCOM complex components to the BSEP promoter was disrupted in cholestasis induced by common bile duct ligation (CBDL) (Ananthanarayanan et al., 2011). This could provide a plausible explanation for paradoxal lack of BSEP induction in cholestasis, despite potential BS-dependent FXR activation by accumulating intrahepatic BSs. In addition, secondary co-activators such as co-activator-associated arginine methyltransferase 1 (CARM1) (Lee et al., 2005) and direct methylation of FXR by Set7/9 methyltransferase facilitate FXR/RXRa-dependent BSEP transcription (Ananthanarayanan et al., 2004; Balasubramaniyan et al., 2012). The recent discovery of FXR-mediated BSEP regulation through recruitment of a transcription co-activator, steroid receptor co-activator 2 (SRC2), provides a novel mechanistic link between intracellular energy depletion 60 A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 and fat absorption. Hepatocyte-specific SRC2/ mice showed reduced BSEP gene expression and developed signs of cholestasis such as increased intrahepatic and serum BS levels and impaired dietary fat absorption, while dietary CA supplementation or restoration of hepatic BSEP expression by adenoviral vector rescued cholestatic phenotype in these mice (Cho- pra et al., 2011). Since SRC2 is phosphorylated and activated by the intracellular energy sensor AMP-activated protein kinase (AMPK), this study provided a novel functional crosstalk between hepatic energy depletion and FXR-mediated BS secretion to promote dietary fat absorption and further emphasizes the key role of BSEP in lipid metabolism (Chopra et al., 2011). In line with these findings, AMPK activation is directly involved in formation and maintenance of the hepatocyte canalicular network (Fu et al., 2010). Thus, AMPK activators such as the antidiabetic drug metformin and the antiischemic drug 5-amino- imidazole-4-carboxamide ribonucleotide (AICAR) may – apart from their direct action on intracellular metabolism – also have indirect beneficial effects through regulation of biliary BS secretion and promotion of cellular energy supplementation by BSs. In addition, AMPK activators are likely to have cytoprotective effects through promotion of AMPK–SRC2–BSEP-mediated elimination of BSs. Apart from FXR, several other transcriptional factors also target BSEP gene expression. The human and mouse BSEP promot- ers contain a response element for the liver receptor homologue 1 (LRH1/NR5A2) (Song et al., 2008), an essential regulator of development, metabolism and BS synthesis (Fayard et al., 2004). LRH-1 mediates CDCA- or FXR-dependent maximal BSEP transcription, whereas its loss markedly reduces expression of hepatobiliary transporters BSEP, NTCP, MRP2 and multidrug resistance-associated protein 3 (MRP3/ABCC3) as well as nuclear receptors FXR and short heterodimer partner (SHP/NR0B2) (Lee et al., 2008; Mataki et al., 2007). Interestingly, the FXR target SHP negatively regulates LRH-1-mediated BSEP transactivation (Kerr et al., 2002), a finding that appears inconsistent with BS-FXR-dependent induction of BSEP. However, BSEP is a direct target of FXR and LRH-1, and therefore, FXR- or LRH-1-mediated induction is likely to dominate over BS-SHP-mediated repression (Song et al., 2008). Since phospholipids (PLs) bind LRH-1 (Krylova et al., 2005; Ortlund et al., 2005), they could in addition to their protective role against biliary BS toxicity (Cohen et al., 1994; Smit et al., 1993) also reduce intracellular BS toxicity through promotion of LRH-1-mediated canalicular export. In support of this assumption, dietary lecithin was protective in mice lacking the canalicular PL exporter multidrug resistance protein 2 (MDR2/ABCB4, human orthologue of MDR3) after dietary CA supplementation (Lamireau et al., 2007), but had no effects on development of spontaneous liver injury without BS challenge in this model (Baghdasaryan et al., 2008). Another important protective mechanism against BS toxicity is the upregulation of BSEP as part of the primary cell response to oxidative stress. Nuclear factor erythroid 2-related factor 2 (NRF2) mediates antioxidative defense through heterodimer formation with musculo-aponeurotic fibrosacroma (MAF) protein and binding to the MAF recognition element (MARE) in the promoter of target genes (Itoh et al., 1997). Two MAREs were identified in the human BSEP promoter and mutations of the predicted MARE1 region abolished BSEP induction by a potent NRF2 activator oltipraz (Weerachayaphorn et al., 2009). Thus, in addition to direct anti-oxidative effects, NRF2 activators may diminish liver injury through canalicular elimination of potentially toxic BSs. Apart from the above mentioned mechanisms, BSEP transcription is also induced by ligands of the pregnane X receptor (PXR/NR1I2) (Teng and Piquette-Miller, 2005), whereas several in vitro studies reported controversial effects on the glucocorticoid receptor (GR/NR3C1). Although the GR agonist dexamethasone was essential for BSEP expression in cultured rat primary hepatocytes (Warskulat et al., 1999), it failed to induce BSEP expression in sandwich cultured cells forming functional canalicular units (Turncliff et al., 2006). Importantly, BSEP transcription is negatively regulated in pathological conditions such as inflammation or drug toxicity. A clear decrease of peri-portal BSEP was detected in CBDL- and lipopolysaccharide (LPS)-induced liver injury, whereas peri-central expression remained unchanged (Donner et al., 2007). BSEP restoration after blockade of tumor necrosis factor alpha (TNF-a or interleukin-1 beta (IL-1b (by etanercept or anakinra respectively) in models of CBDL-, LPS- and TPN-induced liver injury established a pathogenetic role of inflammatory cell-derived cytokines for BSEP inhibition (Carter and Shulman, 2007; Donner et al., 2007; Li et al., 2012). In support of this hypothesis, TNF-a, IL-1b and interleukin-6 (IL-6) reduced BSEP gene expression in human sandwich-cultured hepatocytes (Diao et al., 2010). Reduced binding of FXR/RXRa heterodimer to IR-1 (Geier et al., 2005a) and direct interaction of the nuclear factor kappa-B (NF-jB) subunits with FXR (Gadaleta et al., 2011) are the main mechanisms mediating cytokine-dependent BSEP inhibition. In addition, cytokines caused downregulation of RXRa, an obligate partner for heterodimer formation with the major BSEP stimulator FXR and PXR (Beigneux et al., 2000, 2002; Pascussi et al., 2000c; Teng and Piquette-Miller, 2005). Notably, hepatotoxic effects of the antidiabetic drug troglitazone (agonist of peroxisome proliferator-activated receptor gamma (PPARc)) are mediated through stable complex formation with the FXR ligand binding domain and suppression of FXR-mediated BSEP transactivation (Kaimal et al., 2009). How- ever, this effect of troglitazone was PPARc-independent as other PPARc activators did not interfere with FXR activity.

4. Functional role of OSTa/OSTb in health and disease

In addition to canalicular BS export, retrograde elimination/overflow of BSs into sinusoidal blood through basolateral efflux transporters represents an alternative rescue mechanism to reduce intracellular BS load. This process is mediated by several transport proteins with wide substrate specificity, such as the organic solute transporter (OST/SLC51), MRP3 and multidrug resistance-associated protein 4 (MRP4/ABCC4). Although MRP3 and especially MRP4 are induced and play a protective role in cholestasis (Mennone et al., 2006; Zelcer et al., 2006), MRP4 is likely to be regulated mainly at the posttranscriptional level (Denk et al., 2004). In contrast, transcriptional upregulation of OST is even more pronounced (Wagner et al., 2003; Zollner et al., 2003b), indicating that adaptive upregulation of OST may be the predominant mechanism A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 61 of basolateral BS elimination. OST is composed of 2 proteins – OSTa and OSTb –(Wang et al., 2001b) and is expressed on the basolateral surface of cell populations critically involved in BS transport/reabsorption: enterocytes, hepatocytes, bile duct lining cells – cholangiocytes and tubular renal cells (Ballatori et al., 2005; Dawson et al., 2005; Rao et al., 2008). OSTa/OSTb expression in hepatocytes enables BS elimination into blood sinusoids, whereas in enterocytes it is critical for intestinal BS absorption and their enterohepatic circulation. Its expression in cholangiocytes serves cholangiocellular transport and intrahepatic recycling of BSs. Apart from BSs OSTa/OSTb also mediates transport of molecules such as estrone 3-sulfate, dehydroepiandrosterone, digoxin and prostaglandine E2 (Ballatori, 2011; Ballatori et al., 2005; Dawson et al., 2010; Seward et al., 2003). Importantly, in contrast to humans, OSTa/OSTb expression is very low in mouse liver (Ballatori et al., 2005; Dawson et al., 2005). Although hepatic OSTa/OSTb is induced under cholestatic conditions both in patients and rodents (Boyer et al., 2006; Cui et al., 2009) its pathogenetic role in liver diseases remains poorly understood. Notably, OSTa deficiency in mice resulted in a reduced BS pool size and impaired cholesterol absorption without development of cholestatic phenotype or liver damage (Ballatori et al., 2008; Rao et al., 2008). Furthermore, experimental models of obstructive cholestasis and dietary BS supplementation showed attenuated liver injury in OSTa/ mice through involvement of adaptive mechanisms in liver (phase I and II detoxification, phase III elimination through MRP4) and augmentation of renal BS excretion (Denk et al., 2004; Soroka et al., 2010, 2011). In addition to the above mentioned mechanisms, OSTa deficiency reduced BS pool size through retention of BSs in enterocytes and BS-FXR-fibroblast growth factor 15 (FGF15)-mediated inhibition of hepatic CYP7A1 (the rate-limiting enzyme in BS synthesis) (Lan et al., 2011, 2012; Soroka et al., 2011). Whether OSTa/OSTb dysfunction may cause elevation of serum cholesterol levels and promote development of gallstone disease due to FGF19 (human orthologue of FGF15)-mediated inhibition of cholesterol utilization and decreased biliary excretion remains to be explored in detail. However, non-obese female gallstone patients had reduced intestinal OSTa/OSTb mRNA as well as protein levels, which correlated with lower expression of FXR and its other targets apical sodium-dependent bile acid transporter (ASBT) and FGF19 (Renner et al., 2008). Given the fact that OSTa/OSTb induction in liver will promote basolateral BS elimination, whereas its inhibition in gut will reduce BS pool size (through decreased absorption and synthesis), organ-specific modulation of OST-mediated BS transport appears to be an attractive therapeutic concept in cholestasis.

5. Transcriptional regulation of OSTa/OSTb

OST-mediated BS transport requires co-expression of both subunits by 2 distinct genes: OSTa and OSTb (Dawson et al., 2005; Seward et al., 2003; Wang et al., 2001b). Importantly, coexpression and heterodimerization of OSTa and OSTb subunits and their mutual interaction enables the proper function of the transporter (Dawson et al., 2005; Seward et al., 2003). Spe- cifically, normal OSTa gene and protein expression are critical for the proper function of OSTb (Li et al., 2007; Rao et al., 2008; Sun et al., 2007), whereas OSTb promotes trafficking of OSTa to the cell membrane and its functional activity (Christian et al., 2012; Wang et al., 2001b). Since OSTa and OSTb protein levels correlate with respective transporter mRNA levels in human ileal biopsies, OSTa/OSTb is believed to be regulated mainly at the transcriptional level (Renner et al., 2008). The key role of BS-FXR-mediated mechanism of OSTa/OSTb gene regulation was uncovered in mice deficient in the ileal BS uptake transporter ASBT (ASBT/ mice) (Dawson et al., 2005). Interestingly, blockade of BS uptake in ileum repressed OSTa/OSTb expression in this part of the gut, whereas its expression in colon was induced due to high transporter-independent intracellular BS flux (Dawson et al., 2005). Indeed, OSTa/OSTb gene transcription is directly controlled by FXR in human and mouse tissues (Landrier et al., 2006; Lee et al., 2006) and loss of FXR abolished OSTa/OSTb induction by CA feeding (Zollner et al., 2006b). Two functional FXR-binding sites have been identified in the human OSTa and one in the OSTb gene promoter (Landrier et al., 2006). Moreover, human OSTa/OSTb is also induced by GR, whereas vitamin D receptor (VDR/NR1I1) and PXR are unlikely to play a key regulatory role for the human transporter (Khan et al., 2009). Of note, mouse OSTa/OSTb gene expression may be induced by the liver X receptor (LXR/NR1H3) through binding to the elements of FXRE IR-1 (Okuwaki et al., 2007). In contrast, LRH-1 is responsible for negative regulation of mouse OSTa/OSTb expression in response to BSs (Frankenberg et al., 2006). However, positive OSTa/OSTb regulation by FXR appears to be dominant and LRH-1 is unlikely to play a critical role in baseline expression of OST transporters. Collectively, these findings suggest that FXR and GR ligands could have therapeutic potential to induce OSTa/OSTb-mediated basolateral BS export from hepatocytes in humans.

6. Functional role of NTCP in health and disease

During their enterohepatic circulation, approximately 95% of biliary BSs are efficiently reabsorbed in intestine and return to liver where they are taken up by hepatocytes and undergo a further cycle of biliary excretion and subsequent enterohepatic circulation (Hofmann, 1999). Hepatic uptake of BSs takes place against a 5–10-fold concentration gradient at the basolateral surface of hepatocytes and is mediated through the Na+-taurocholate co-transporting polypeptide (NTCP/SLC10A1) (Ananthanarayanan et al., 1994; Hagenbuch et al., 1991; Stieger et al., 1994) and a group of Na+-independent organic anion transporting polypeptides (OATPs) (Nathanson and Boyer, 1991). NTCP mediates Na+-dependent uptake of all physiological BSs in their conjugated form (Stieger et al., 1994), estrone-3-sulphate, thyroid hormones (Meier and Stieger, 2002) and drugs bound to TCA, e.g., chlorambucil-taurocholate (Kullak-Ublick et al., 1997). In contrast to NTCP OATPs have a lower affinity for BSs (Na+-independent transport) and broader substrate specificity (Konig et al., 2000; Kullak-Ublick et al., 2001). 62 A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76

Although no mutations of NTCP have been identified as primary causative factor for human cholestasis, the NTCP variant Ser267Phe in Chinese-Americans showed a near complete loss of function of BS transport with preserved uptake of other substrates, thereby uncovering the critical role of this region for BS recognition (Ho et al., 2004). Furthermore, dependent on substrate specificity, NTCP variants may significantly impair the uptake of TCA and drugs such as statins, thereby limiting their clinical effectiveness (Choi et al., 2011; Pan et al., 2011). NTCP gene expression is reduced in human cholestatic conditions such as biliary atresia, advanced primary biliary cirrhosis (PBC) and cholestatic alcoholic liver injury (Shneider et al., 1997; Zollner et al., 2003a, 2001) as well as in several cholestatic animal models (Gartung et al., 1996; Lee and Boyer, 2000; Trauner et al., 1998; Zollner et al., 2003b). However, the pathophysiological role of altered NTCP expression in cholestasis remains unclear. Nevertheless, NTCP repression may contribute to impairment of bile formation, although this mechanism appears to reflect hepatocyte adaptation to increased intracellular BS levels.

7. Transcriptional regulation of NTCP

Repression of NTCP in response to BS challenge in normal/pathologic conditions is an important step in protection against intracellular BS overload since the majority of BSs excreted into bile are derived from the enterohepatic circulation. NTCP regulation differs considerably between species. Studies in knock-out or overexpression animal models identified the key transcriptional regulators of rodent NTCP such as homeodomain protein hepatocyte nuclear factor 1 alpha (HNF-1a), hepatocyte nuclear factor 4 alpha (HNF-4a), RXRa, hepatocyte nuclear factor-3b (HNF-3b) and FXR/SHP (Denson et al., 2001; Hayhurst et al., 2001; Jung and Kullak-Ublick, 2003; Karpen et al., 1996; Lee et al., 2000; Rausa et al., 2000; Shih et al., 2001). Despite virtually absent baseline NTCP expression in models of HNF-1a deficiency and deficiency of the binding site for retinoic acid receptor alpha (RARa/NR1B1/RXRa heterodimer, no respective response element was found in the min- imal promoter of mouse NTCP (Geier et al., 2003b; Jung et al., 2004b). In contrast, HNF-4a directly binds to the murine NTCP promoter through functional HNF-4a-response element (Geier et al., 2008) and PGC-1a potentiates NTCP transactivation by HNF-4a. Since HNF-1a controls HNF-4a transcription, repressed NTCP expression in HNF-1a deficiency may reflect potentially HNF-4a-mediated mechanism (Hansen et al., 2002; Odom et al., 2004). Importantly, the human NTCP promoter is devoid of a TATA regulatory box (Shiao et al., 2000), which explains the absence of binding sites for respective transcriptional factors regulating murine NTCP. Among the known binding sites of NTCP promoter only the HNF-3b response element is shared by the mouse, rat and human sequence (Jung et al., 2004b). Human NTCP is also positively regulated by the GR, for which PGC-1a and components of co-activating complex ASCOM act as co-activators (Ananthanarayanan et al., 2011). In addition, cAMP response element members of the CCAAT/enhancer-binding protein (C/EBP) family were able to transactivate human NTCP (Jung et al., 2004b; Shiao et al., 2000), whereas C/EBP mutations reduced NTCP expression by 70% (Shiao et al., 2000). Negative feedback regulation of murine NTCP by BSs is mediated through FXR-SHP-mediated prevention of its positive regulation by RXRa/RARa (Denson et al., 2001) or competition of SHP with co-activators for binding to HNF-4a and RXRa (Lee et al., 2000), whereas SHP-mediated negative interaction with GR and PGC-1a represent the main molecular mechanisms mediating BS-dependent repression of human NTCP (Eloranta et al., 2006). Notably, CA feeding repressed NTCP expression in SHP/ mice, indicating that SHP-independent mechanisms may also be involved in mediating NTCP repression in cholestasis (Wang et al., 2003b). Since BSs inhibit human HNF-1a activation by HNF-4a in SHP-independent manner (Jung and Kullak-Ublick, 2003), this mechanism is also likely to be involved in NTCP repression in mice. In addition to BS-mediated

Table 1 Transcriptional regulators of main bile salt transporters BSEP, OSTa/OSTb and NTCP in humans.

Transporter Positive regulators Negative regulators BSEP/ABCB11 FXR/NR1H4 Pro-inflammatory cytokines TNF-a, IL-6 and IL-1b - Co-activators: - Inhibition of FXR/RXRa binding activity - PGC-1a - Direct interaction of NF-jB with FXR - Components of ASCOM complex - Repression of RXRa - Set7/9 methyltransferase Drugs (e.g., troglitazone) - CARM-1 - Stable complex formation with FXR and - SRC2 suppression of FXR-dependent transactivation LRH1/NR5A2 Female hormones - Potentiates FXR-mediated - b-estradiol transactivationNRF2 PXR/NR1I2 OSTa/OSTbSLC51A/SLC51B FXR/NR1H4 Not known GR/NR3C1 NTCP/SLC10A1 GR/NR3C1 FXR Co-activators - SHP-mediated negative interaction with : - PGC-1a RXRa, GR and PGC-1a - Components of ASCOM complex IL-1b RARa/RXRaC/EBP - Reduction of RARa/RXRa binding activity through inhibition of RXRa phosphorylation A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 63 mechanisms, endotoxin/cytokine-mediated inhibition of main NTCP regulators RARa/RXRa, HNF-4a and HNF-1a or their binding activity may also contribute to NTCP repression in cholestasis (Beigneux et al., 2000; Geier et al., 2005a, 2003b; Green et al., 1996; Hartmann et al., 2002; Moseley, 1999; Moseley et al., 1996; Trauner et al., 1998). Inhibition of c-Jun N-terminal kinase (JNK)-mediated RXRa phosphorylation is involved in reduced RARa/RXRa binding activity and NTCP downregulation by Il-1b (Li et al., 2002). In line with rodent data, IL-1b also suppressed human NTCP transcription and protein levels (Le Vee et al., 2008). However, cytokine inactivation or Kupffer cell depletion failed to restore inhibition of NTCP gene expression in mice (Geier et al., 2005b). In line with these findings, decreased nuclear HNF-1a and HNF4a protein levels and inhibited HNF-1a binding activity were also not restored after cytokine inactivation in CBDL (Geier et al., 2005b). Fur- thermore, reduced levels of the key regulators (HNF-1a, HNF-4a, RXR/RARa) did not differ between FXR+/+ and FXR/ mice after CBDL or LCA feeding, despite pronounced difference in NTCP expression (Zollner et al., 2005). These findings indicate that BS-mediated mechanisms, but not cytokines play the predominant role in downregulation of NTCP in cholestasis (Geier et al., 2005b). Finally, sex hormones also play an important role in regulation of NTCP gene expression as demonstrated by 2-fold higher expression in male compared with female rats. NTCP expression was repressed in pregnant female animals or after estradiol administration in males (Arrese et al., 2003; Bossard et al., 1993; Geier et al., 2003a; Simon et al., 1996), while ovarectomy resulted in increased NTCP expression in females (Simon et al., 2004). These data provides a potential molecular mechanism for sex hormone-induced cholestasis. Importantly, models of experimental hypophysectomy provided evidence for the role of the complex interplay of pituitary hormones in regulating NTCP expression by sex hormones (Simon et al., 2004). The pituitary gland hormone prolactin facilitates NTCP transcription through prolactin receptor-mediated binding of signal transducers and activators of transcription (STAT-5) to its two binding sites in the rat NTCP promoter (Ganguly et al., 1997), whereas estradiol repressed PLR-induced NTCP upregulation in human cells (Cao et al., 2004). Similarly, a STAT-5-mediated mechanism is involved in growth hormone-mediated upregulation of rat NTCP (Cao et al., 2001). Taken together, transcriptional regulation of the main hepatobiliary BS transporters BSEP, OSTa/b and NTCP play an important role in cholestatic liver disease. The key positive and negative transcriptional regulators of human BSEP, OSTa/OSTb and NTCP are summarized in Table 1.

8. Novel therapeutic strategies targeting transcription factors in cholestasis

Pharmacological stimulation of canalicular BS efﬂux through BSEP and basolateral elimination through OSTa/OSTb or inhibition of hepatocellular BS uptake through NTCP via targeted stimulation of the key regulatory transcription factors may have important clinical applications and represents a promising direction for novel drug development in cholestasis. Several traditional drugs widely used to treat cholestatic liver disorders have turned out to act at least in part through activation of transcription factors regulating hepatobiliary transport and metabolism. Moreover, key regulatory transcription factors have also become the focus of targeted therapies in cholestasis.

8.1. Ursodeoxycholic acid and derivatives

Currently, pharmacological therapy of cholestatic liver diseases is limited to use of ursodeoxycholic acid (3a,7b-dihy- droxy-5b-cholanoic acid or UDCA), which represents 1–3% of total BSs in human bile (Hofmann, 1994). Importantly, UDCA does not activate FXR (Makishima et al., 1999; Parks et al., 1999; Sato et al., 2008), but binds to GR (discussed below) (Miura et al., 2001) and is capable of activating PXR after its transformation to LCA by intestinal ﬂora (Staudinger et al., 2001b; Xie et al., 2001). Anti-cholestatic effects of this drug are mediated through induction of BS-dependent as well as BS-independent bile secretion by several mechanisms (Jazrawi et al., 1994; Paumgartner and Beuers, 2004; Poupon and Poupon, 2000; Trauner and Boyer, 2003). These include induction of BSEP and MRP2 on the transcriptional level in mice (Fickert et al., 2001) as well as posttranscriptional mechanisms inﬂuencing vesicular transport, exocytosis and membrane insertion (Beuers

Table 2 Molecular targets of FXR in liver and potential beneﬁcial effects of FXR activation in cholestasis.

Molecular targets of FXR in liver Effects in cholestasis - Canalicular export of BSs through BSEP and MRP2 Reduction of intracellular BS - Basolateral BS elimination via OSTa/OSTb toxicity - Inhibition of NTCP- and OATP1B1-mediated BS uptake - Inhibition of BS synthesis (inhibition of CYP7A1 through FGF19- and SHP- mediated mechanisms, inhibition of CYP8B1and CYP27A1) - Promotion of BS detoxification (through upregulation of CYP3A4, SULT2A1, UGT2B4) - Reduced biliary excretion of BSs through inhibition of synthesis Reduction of bile toxicity - Canalicular PL secretion through MDR3 and promotion of mixed micelle formation - Promotion of HCO3 -rich bile secretion through carbonic anhydrase 14 - Induction of gallbladder secretion via VPAC-1 - Repression of pro-inflammatory gene expression through interaction with NF-jB Inhibition of inflammation 64 A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 et al., 2001; Dombrowski et al., 2006; Kubitz et al., 2004; Kurz et al., 2001; Milkiewicz et al., 2002). Interestingly, despite increased BSEP protein levels BSEP mRNA remained unchanged in non-cholestatic gallstone patients after UDCA administration, indicating that predominantly posttranscriptional mechanisms are involved (Marschall et al., 2005). In addition, UDCA restored pathologically reduced expression of the biliary HCO3 exchange transporter anion exchanger 2 (AE2/SLC4A2) in PBC patients (Medina et al., 1997; Prieto et al., 1999) and its combination with glucocorticoids synergetically induced AE2 alternate promoter in human cells (Arenas et al., 2008). Furthermore, UDCA also has several immunomodulatory effects in vitro (Lacaille and Paradis, 1993; Nishigaki et al., 1996; Yamazaki et al., 1999; Yoshikawa et al., 1992). These pleiotropic mechanisms may explain the beneficial clinical effects of UDCA in a broad range of cholestatic disorders including PBC (biochemical and histological improvement and prolonged survival without liver transplantation) (Lazaridis et al., 2001; Paumgartner and Beuers, 2004; Poupon, 2011, 2012, 2000) and ICP (improved maternal pruritus, serum transaminases as well as neonatal out- comes) (Bacq et al., 2012; Brites, 2002; Glantz et al., 2005, 2008; Kondrackiene et al., 2005; Mazzella et al., 2001; Palma et al., 1997). However, standard doses of UDCA did not improve survival in primary sclerosing cholangitis (PSC) and high dose UDCA was even associated with higher risk of severe side effects and mortality (Lindor et al., 2009). A side chain shortened derivative of UDCA, 24-norUDCA reduced serum liver enzymes, induced bile flow and improved hepatic inflammation and fibrosis in MDR2/ (ABCB4/) model of sclerosing cholangitis (Fickert et al., 2006). Beneficial effects of 24-norUDCA in this model of liver injury were associated with coordinated induction of BS detoxification (through CYP2B10, CYP3A11 and SULT2A1) and basolateral export through alternative transporters MRP3 and MRP4 on transcriptional level without significant effects on BSEP or NTCP gene expression (Fickert et al., 2006). Importantly, in comparison with UDCA, 24-norUDCA is more resistant to amidation, which may promote its cholehepatic shunting and thereby contribute to increased secretion of protective HCO3 . Clinical trials with 24-norUDCA for PSC have been already initiated and the results of a phase II randomized double-blind multi-center placebo-controlled study will provide first answers about clinical efficacy of this promising compound. Importantly, derivatives of 24-norUDCA tauro-norUDCA and di-norUDCA do not share pharmacological properties of 24-norUDCA and failed to improve liver injury in the MDR2/ model. Moreover, di-norUDCA even worsened liver injury, underlining the unique beneficial properties of 24-norUDCA due to its resistance to amidation and cholehepatic shunting (Halilbasic et al., 2009).

8.2. Therapeutic potential of FXR activators

Since FXR represents a master regulator of BS homeostasis and inflammation by targeting a broad spectrum of molecular mechanisms (Modica et al., 2012; Trauner et al., 2011; Wagner et al., 2011; Wang et al., 2008) its pharmacological activation may exert multiple protective mechanisms in cholestasis. The main mechanisms by which FXR activation may protect against cholestatic liver injury are summarized in Table 2. A significant proportion of FXR’s therapeutic effects in cholestasis may be due to the fact that FXR regulates gene expression of the key BS transporters including uptake transporter NTCP and export transporters BSEP and OSTa/OSTb in addition to promoting BS detoxification through phase I hydroxylation by CYP3A4 (Gnerre et al., 2004), phase II sulfoconjugation by SULT2A1 (Song et al., 2001) and glucoconjugation by UGT2B4 (Barbier et al., 2003b). Thus, FXR activation by high affinity agonists with no side effects may represent an attractive therapeutic concept in cholestasis. Non-steroidal compounds GW4064, FXR-450 or WAY-362450 and PX20350 are potent FXR activators (Abel et al., 2010; Maloney et al., 2000; Mehlmann et al., 2009; Pellicciari et al., 2002). GW4064 induced BSEP, SHP, MRP2 and MDR2, inhibited NTCP, repressed BS synthesis and showed hepatoprotective effects in rat models of intrahepatic (alpha-naphthylisothiiocyanate administration) and extrahepatic (CBDL) cholestasis (Liu et al., 2003). Furthermore, GW4064 induced BS-independent bile secretion in human gallbladder through FXR-mediated induction of vasoactive intestinal peptide receptor 1 (VPAC1) transcription, the major regulator of bile secretion (Chignard et al., 2005). A recent study showed that GW4064 and PX20350 may also prevent/treat hepatocellular carcinomas through FXR-dependent induction of tumor suppressor gene NMYC downstrean-regulated gene 2 (NDRG2) (Deuschle et al., 2012). The currently available ligands for clinical trials represent chemical modifications of endogenous BSs (Table 3). Specifically, a semi-synthetic

Table 3 FXR ligands with potential clinical application.

Agonist Clinical application Comments CDCA (Chenofalk TN) Gallstone disease, cerebrotendinous Hepatotoxicity in rhesus monkey, but not in humans xanthomatosis OCA/6-ECDCA/INT-747 PBC, NAFLD/NASH, bile acid diarrhoea, Beneficial in combination with UDCA (biochemically non-responders to (semisynthetic derivative of gallstone disease, portal hypertension UDCA) or as monotherapy (treatment-naïve patients) in PBC. CDCA) Dose-dependent pruritus INT-767 (synthetic derivative Preclinical Preclinical: biochemical and histological improvement in MDR2/ of OCA) mouse model of sclerosing cholangitis GW4064 (synthetic agonist) Preclinical Not further developed for clinical use FXR-450/WAY-362450 NAFLD Phase 1 trial in healthy Japanese men was terminated due to (synthetic agonist) pharmacokinetic issues PX-104 NAFLD Phase 2 trial to assess the safety and tolerability in NAFLD patients A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 65 obeticholic acid (OCA) also known as 6-ethylchenodeoxycholic acid (6-ECDCA) or INT-747 was synthesized on the basis of CDCA backbone and is an approximately 100-fold more potent FXR activator (Pellicciari et al., 2002). OCA was beneficial in animal models of LCA-, estrogen-, carbone tetrachloride (CCl4)- or CBDL-induced cholestasis (Fiorucci et al., 2005; Pellicciari et al., 2002). It is important to consider that in contrast to these models of liver injury, dietary OCA supplementation dete- riorated liver injury in the MDR2/ model despite its strong FXR activating capacity (Baghdasaryan et al., 2011). Since biliary secretion of protective PLs is absent in MDR2/ mice (corresponding to liver disease from MDR3 mutations in humans), increased biliary excretion of hydrophobic OCA and concominant reduction of endogenous BSs (in mice mainly in form of more hydrophilic muricholic acid) could result in a net increase of more hydrophobic BS proportion in bile, thereby promoting liver injury in this specific model. Recent clinical trials have shown beneficial effects of OCA treatment in patients with PBC. Short- and long-term combination of OCA with UDCA reduced serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) levels in PBC patients biochemically not responding to UDCA treatment (Hirschfield et al., 2011; Mason et al., 2010). Moreover, OCA monotherapy significantly reduced serum ALT, ALP and gamma-glutamyl transpeptidase (GGT) levels in treatment-naive PBC patients (Kowdley et al., 2011). Itching was the most common adverse effect in patients receiving high dose OCA treatment. A phase III, double blind, placebo controlled trial and long term safety study of low-dose OCA treatment has been initiated in PBC patients. Further modifications of OCA led to synthesis of a semi-synthetic 23-sulfate-derivative 6a-ethyl-3a,7a,23-trihydroxy-24- nor-5b-cholan-23-sulfate sodium salt also called INT-767 (Rizzo et al., 2010). In contrast to OCA, INT-767 is a hydrophilic compound with higher affinity to FXR. In addition, INT-767 may also activate the membrane BS receptor TGR5/GPBAR1 (Rizzo et al., 2010). Importantly, INT-767 significantly reduced serum ALT levels, decreased portal inflammation and biliary fibrosis in the MDR2/ animal model of sclerosing cholangitis (Baghdasaryan et al., 2011). These beneficial effects were mediated by several FXR-dependent hepatoprotective mechanisms including induction of BSEP mRNA and protein levels, promotion of BS-independent bile flow through promotion of protective HCO3 secretion with simultaneous inhibition of BS synthesis and NTCP repression. Altogether, INT-767 treatment resulted in lower BS and higher HCO3 output into bile. In addition, since INT-767 may also act as a potent activator of the membrane BS receptor TGR5, it may also induce bile secretory function though non-transcriptional cAMP signaling pathways (Kawamata et al., 2003; Maruyama et al., 2002). Thus, INT-767 represents a very promising new drug to treat non-obstructive cholestasis in humans. However, TGR5 expression is induced in cholangiocellular carcinoma, where it may confer resistance to apoptosis (Keitel et al., 2011), indicating that ligands which can also activate TGR5 have to be seen with some caution. Notably, FXR activation induces hepatocellular proliferation in animal models (Baghdasaryan et al., 2011; Huang et al., 2006) which theoretically may raise concerns in regards to risk for tumor development. However, FXR directly regulates tumor suppressor NDRG2 (Deuschle et al., 2012) and may also prevent tumor development via its anti-inflammatory properties. Conversely, FXR and BSEP expression is reduced in hepatocellular (Chen et al., 2012; Su et al., 2012). Finally, stimulation of bile flow may have critical deleterious effects in obstructive cholestasis (Stedman et al., 2006; Wagner et al., 2003; Zollner et al., 2003a). Therefore, preserved biliary drainage will be necessary to fully achieve beneficial effects of FXR activators. However, since FXR is expressed in almost all tissues and regulates a broad range of metabolic pathways FXR ligands are likely to have several additional metabolic off-target effects. Finally, endogenous BSs as well as hepatobiliary transport systems differ considerably between species, which makes it difficult to predict the undesired effects of FXR activation in humans based on animal studies. Thus, carefully designed clinical studies are required to answer all these open questions. Since frequent BSEP mutations are associated with impaired trafficking of BSEP from the ER to the plasma membrane, pharmaceutical targeting of post-transcriptional regulatory mechanisms represents another promising approach to reduce cholestasis (discussed in detail in chapter by J.L. Boyer). Interestingly, the natural ligands/substrates of BSEP, BSs, arise as perfect candidates to act as pharmacological chaperones promoting proper folding and trafficking of mutated BSEP (Misawa et al., 2012b). Novel derivatives of GW4064 compound enhanced BSEP transport activity through their function as chaperons and the 7c analog of the reverse-amide GW4064 derivative has been identified as selective BSEP function enhancer (Misawa et al., 2012a,b). Thus, separation of FXR-agonistic activity from BSEP function-enhancing activity will help to selectively target cholestatic liver injury without broad metabolic effects of FXR.

8.3. Therapeutic potential of CAR and PXR

In obstructive cholestasis, detoxification and basolateral elimination of BSs without induction of canalicular secretion may be critical. Genes encoding hepatocellular drug metabolizing enzymes and alternative transporters are direct targets of nuclear receptors such as constitutive androstane receptor (CAR/NR1I3) and PXR (NR1I2) (Chen et al., 2003b, 2004; Ferguson et al., 2005; Gerbal-Chaloin et al., 2002; Goodwin et al., 2002, 1999; Nebert and Jones, 1989), establishing a sub- stantial role of these transcriptional factors in defense against toxic liver injury (Zollner et al., 2006a). In addition to stimu- lating bilirubin clearance (Chen et al., 2003a; Huang et al., 2003, 2004; Kast et al., 2002) and BS detoxification (Honkakoski et al., 1998; Saini et al., 2004; Sueyoshi et al., 1999) CAR activation promotes MRP4-mediated basolateral elimination of BSs (Chai et al., 2011). Importantly, CAR ligands phenobarbital and a component from Artemisia capillaris (dimethylesculetin) which is used in Chinese herbal teas Yin Zhi Huang and Yin Chin efficiently reduced pruritus and neonatal jaundice (Bachs et al., 1989; Bloomer and Boyer, 1975; Huang et al., 2004; Stiehl et al., 1972). However, CAR activation was hepatotoxic in mice despite significant reduction of serum BS and bilirubin levels (Wagner et al., 2005; Yamazaki et al., 2011). Furthermore, CAR ligands promoted hepatic tumor development (Hojo et al., 2012; Huang et al., 2005; Kiyosawa et al., 2008; Yamamoto 66 A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 et al., 2004) through upregulation of the anti-apoptotic effector myeloid cell leukemia factor 1 (MCL-1) gene expression (Baskin-Bey et al., 2006; Morita et al., 2011). Apart from CAR, PXR may also be beneficial in cholestasis by induction of BS hydroxylation (Marschall et al., 2005; Xie et al., 2000), inhibition of BS synthesis (Staudinger et al., 2001a) and bilirubin clearance (Chen et al., 2003a; Huang et al., 2003, 2004; Kast et al., 2002) as well as inhibition of serum cholestatic enzyme autotaxin activity (Kremer et al., 2010, 2012). PXR ligand rifampicin improved pruritus in cholestatic patients (Bachs et al., 1989; Cancado et al., 1998; Yerushalmi et al., 1999) and reduced serum liver enzymes in PBC and animal models of liver injury (Staudinger et al., 2001a; Teng and Piquette-Miller, 2005, 2007; Xie et al., 2001). However, rifampicin therapy may be associated with development of hepatitis and an increase of serum liver enzymes in 7% of patients (Bachs et al., 1992; Prince et al., 2002). Apart from these undesired effects, induction of drug-metabolizing enzymes by CAR or PXR may induce generation of reactive metabolites and have critical importance for drug interactions (Goldstein and de Morais, 1994; Miners and Birkett, 1998). Together, these findings indicate that despite desired induction of BS detoxification and elimination mechanisms, CAR and PXR activation is associated with the risk of tissue damage and tumor development. Therefore, ligands of these transcriptional regulators, if strongly indicated, may be administered only for a short-term treatment. Furthermore, CAR antagonists may represent an interesting strategy to treat oxidative stress-mediated liver injury in humans (Kublbeck et al., 2011). However, further studies are required to establish the biological role of CAR inhibition in health and disease.

8.4. Therapeutic potential of GR, PPARa, PPARc and VDR

In addition to FXR, CAR and PXR there is arising evidence for the role of additional transcriptional factors such as GR, peroxisome proliferator-activated receptors alpha (PPARa/NR1C1) and gamma (PPARc/NR1C3) and VDR in cholestasis. Gluco- corticoids, which are widely used in clinical practice due to their pronounced immunosuppressive action, but may also play an important role in cholestasis through transcriptional regulation of BS transporters NTCP, ASBT and OSTa/OSTb (Eloranta et al., 2006; Jung et al., 2004a; Khan et al., 2009). Moreover, GR may interact with other transcription factors such as CAR, PXR and RXRa leading to synergetic stimulation of target gene expression (Pascussi et al., 2000a,b; Sugatani et al., 2005; Zimmermann et al., 2009). Combination therapy of UDCA with glucocorticoids induced HCO3 transporter AE2 gene expression in PBC (Arenas et al., 2008; Medina, 2011; Medina et al., 1997; Poupon, 2011; Prieto et al., 1993), which may also explain stimulation of bile secretion in patients with biliary atresia after Kasai operation (Meyers et al., 2003) and HCO3-dependent bile flow in rats (Alvaro et al., 2002). Compared with UDCA monotherapy combination of budesonide (a glucocorticoid with low adverse effects) with UDCA was more efficient with respect to reduction of serum liver enzymes and liver histology in early stage PBC (Leuschner et al., 1999; Rautiainen et al., 2005). However, budesonide monotherapy showed severe side effects and increase in Mayo risk score in UDCA non-responders (Angulo et al., 2000). Furthermore, budesonide treatment in stage 4 PBC patients was associated with portal vein thrombosis and death, thereby establishing an absolute contraindication for budesonide use in late-stage PBC (Hempfling et al., 2003). Notably, GR activation inhibited FXR transcriptional activity and led to cholestasis through recruitment of C-terminal binding protein (CtBP) co-repressor complexes and subsequent induction of BS synthesis and repression of hepatocellular transporters in mice (Lu et al., 2012). Furthermore, suppressed expression of FXR and FXR target genes by glucocorticoids (Rosales et al., 2013) may contribute to development of cholestasis as demonsrated by increased serum BS levels in patients with Cushing syndrome (Lu et al., 2012; Yamanishi et al., 1985). Interestingly, UDCA effects are partially mediated through GR activation (Tanaka and Makino, 1992; Tanaka et al., 1996). Interaction of UDCA with a specific part of the GR ligand-binding domain leads to loss of specific co-activator recruitment and subsequently weak induction of glucocorticoid response element (GRE) gene response while strongly inhibiting NF-jB target genes (Miura et al., 2001). Thus, dissociation of GR-dependent transcription of selective targets by UDCA may represent a very promising start- ing point for development of novel drugs with less undesired effects. Agonists of PPARa, which are widely used as antihyperlipidemic drugs, can induce hepatic detoxification (Barbier et al., 2003a; Fang et al., 2005; Honda et al., 2013) and promote MDR3-mediated canalicular PL secretion (Ghonem and Boyer, 2013; Matsumoto et al., 2004; Roglans et al., 2004; Shoda et al., 2004), modify intestinal BS uptake (Jung et al., 2002) and inhibit BS synthesis (Marrapodi and Chiang, 2000; Patel et al., 2000; Post et al., 2001). Unlike CAR and PXR, direct induction of mitochondrial uncoupling protein 2 gene (UCP2) expression (Patterson et al., 2012) by PPARa may be protective against reactive metabolites and therefore might have a potential in the treatment of BS- and drug-induced toxicity. Indeed, combination of UDCA with PPARa agonists bezafibrate and fenofibrate improved serum liver tests in PBC patients with incomplete biochemical response to UDCA (Caroli-Bosc et al., 2001; Honda et al., 2013; Itakura et al., 2004; Kanda et al., 2003; Levy et al., 2011; Nakai et al., 2000) and even showed histological improvement as monotherapy (Kurihara et al., 2002, 2000; Yano et al., 2002). Since these studies have been conducted in a small number of patients and mainly after a short-term treatment, additional longer treatment studies with higher patient numbers are required to establish the long-term efficacy and safety of fibrate treatment in PBC. In contrast to PPARa, PPARc plays an important role for cholangiocyte injury (Harada et al., 2005) and is critical for the maintenance of a quiescent state of profibrogenic cells (Hazra et al., 2004a,b; She et al., 2005; Zhang et al., 2012). PPARc activation in cholangiocytes and portal myofibroblasts by curcumin improved liver injury and biliary fibrosis in the MDR2/ model of sclerosing cholangitis (Baghdasaryan et al., 2010). Interestingly, PPARc ligand rosiglitazone improved LPS-induced liver injury by attenuating cytokine-mediated nuclear export of RXRa and restoring its binding activity in hepatocytes with A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 67 subsequent induction of BSEP and NTCP in mice (Ghose et al., 2007). Since PPARc is not expressed in hepatocytes, beneficial effects of rosiglitazone on hepatocellular transporter gene expression in vivo and in vitro may reflect indirect mechanisms involving potential effects of rosiglitazone metabolites, activation of additional signaling pathways or interaction with cytokines. Importantly, PPARc agonists showed pronounced side effects and troglitazone was withdrawn from the market due to its hepatotoxic effects, which notably were PPARc-independent (Funk et al., 2001; Snow and Moseley, 2007). Since PPARc is unlikely to influence hepatocellular homeostasis, selective targeting of cholangiocytes and fibrogenic cells by PPARc activators is likely to have major beneficial effects in portal inflammation and biliary fibrosis (Harada and Nakanuma, 2010). Importantly, VDR variants were identified in PBC and autoimmune hepatitis (Fan et al., 2005; Halmos et al., 2000; Tanaka et al., 2009; Vogel et al., 2002). They reduced VDR protein levels and were shown to be inversely correlated with histological severity of nonalcoholic steatohepatitis and viral hepatitis C (Barchetta et al., 2012). However, CDCA-mediated induction of BSEP expression was impaired by VDR interaction with FXR in vitro, indicating potential undesired effects of VDR activation in BS toxicity (Honjo et al., 2006). Given the fact that VDR directly inhibits activation and proliferation of hepatic stellate cells (Abramovitch et al., 2011) and proinflammatory cytokine expression (Ogura et al., 2009), VDR activation is likely to improve cholestasis via improvement of inflammation and fibrosis but not through direct modulation of hepatic BS transport systems. In addition, induction of antibacterial cathelicidin gene expression by VDR in biliary epithelium may be essential for biliary tract sterility and help to prevent/treat cholangiopathies (D’Aldebert et al., 2009). Since limited absorption of fat-soluble vitamins may affect Vitamin D levels in cholestatic patients, VDR activators may also have a beneficial role to prevent/treat osteoporosis in cholestatic patients.

9. Conclusions

Transcriptional regulators of hepatocellular transport systems have emerged as promising drug targets with extraordi- nary potential in the treatment of cholestatic liver disease. Novel and (compared with endogenous BSs) less toxic FXR activators may counteract cholestasis through induction of biliary and sinusoidal BS export, promotion of BS-dependent and BS-independent bile flow, inhibition of BS synthesis and anti-inflammatory effects. Since FXR has very broad tissue and organ distribution and its activation might also impact on multiple mechanisms regulating glucose and lipid homeostasis, selective BSEP or OSTa/OSTb inducers (via FXR) may represent the future direction for novel FXR-directed drug development. GR activators are predicted to be beneficial to control disease flare and acute inflammation, but long-term glucocorticoid therapy will have critical undesired effects. As an alternative, novel GR agonists with an ability to selectively block the NF-jB signaling and limited or absent side effects may represent a future strategy for GR activation in chronic cholestasis. PXR and CAR agonists, which prevent accumulation of cytotoxic BS by induction of their detoxification and basolateral elimination, represent an attractive treatment strategy in obstructive cholestasis. Nevertheless, clinical use of these ligands might be limited due to potential hepatotoxic and tumor promoting effects. Finally, drug interactions and potential impact of other transcriptional factor/nuclear receptor-directed drugs has to be evaluated in depth to minimize potential adverse effects and improve therapeutic efficiency of novel drugs.

Funding

This work was supported by grant F3517 from the Austrian Science Foundation (to MT) and SFB35 project part 3509 (to PC).

References

Abel, U., Schluter, T., Schulz, A., Hambruch, E., Steeneck, C., Hornberger, M., Hoffmann, T., Perovic-Ottstadt, S., Kinzel, O., Burnet, M., et al, 2010. Synthesis and pharmacological validation of a novel series of non-steroidal FXR agonists. Bioorg. Med. Chem. Lett. 20, 4911–4917. Abramovitch, S., Dahan-Bachar, L., Sharvit, E., Weisman, Y., Ben Tov, A., Brazowski, E., Reif, S., 2011. Vitamin D inhibits proliferation and profibrotic marker expression in hepatic stellate cells and decreases thioacetamide-induced liver fibrosis in rats. Gut 60, 1728–1737. Akita, H., Suzuki, H., Ito, K., Kinoshita, S., Sato, N., Takikawa, H., Sugiyama, Y., 2001. Characterization of bile acid transport mediated by multidrug resistance associated protein 2 and bile salt export pump. Biochim. Biophys. Acta 1511, 7–16. Allen, K., Jaeschke, H., Copple, B.L., 2010. Bile acids induce inflammatory genes in hepatocytes: a novel mechanism of inflammation during obstructive cholestasis. Am. J. Pathol. 178, 175–186. Alvaro, D., Gigliozzi, A., Marucci, L., Alpini, G., Barbaro, B., Monterubbianesi, R., Minetola, L., Mancino, M.G., Medina, J.F., Attili, A.F., Benedetti, A., 2002. Corticosteroids modulate the secretory processes of the rat intrahepatic biliary epithelium. Gastroenterology 122, 1058–1069. Ananthanarayanan, M., Ng, O.C., Boyer, J.L., Suchy, F.J., 1994. Characterization of cloned rat liver Na(+)-bile acid cotransporter using peptide and fusion protein antibodies. Am. J. Physiol. 267, G637–G643. Ananthanarayanan, M., Balasubramanian, N., Makishima, M., Mangelsdorf, D.J., Suchy, F.J., 2001. Human bile salt export pump promoter is transactivated by the farnesoid X receptor/bile acid receptor. J. Biol. Chem. 276, 28857–28865. Ananthanarayanan, M., Li, S., Balasubramaniyan, N., Suchy, F.J., Walsh, M.J., 2004. Ligand-dependent activation of the farnesoid X-receptor directs arginine methylation of histone H3 by CARM1. J. Biol. Chem. 279, 54348–54357. Ananthanarayanan, M., Li, Y., Surapureddi, S., Balasubramaniyan, N., Ahn, J., Goldstein, J.A., Suchy, F.J., 2011. Histone H3K4 trimethylation by MLL3 as part of ASCOM complex is critical for NR activation of bile acid transporter genes and is downregulated in cholestasis. Am. J. Physiol. Gastrointest. Liver Physiol. 300, G771–G781. Angulo, P., Jorgensen, R.A., Keach, J.C., Dickson, E.R., Smith, C., Lindor, K.D., 2000. Oral budesonide in the treatment of patients with primary biliary cirrhosis with a suboptimal response to ursodeoxycholic acid. Hepatology 31, 318–323. Arenas, F., Hervias, I., Uriz, M., Joplin, R., Prieto, J., Medina, J.F., 2008. Combination of ursodeoxycholic acid and glucocorticoids upregulates the AE2 alternate promoter in human liver cells. J. Clin. Invest. 118, 695–709. 68 A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76

Arrese, M., Trauner, M., Ananthanarayanan, M., Pizarro, M., Solis, N., Accatino, L., Soroka, C., Boyer, J.L., Karpen, S.J., Miquel, J.F., Suchy, F.J., 2003. Down- regulation of the Na+/taurocholate cotransporting polypeptide during pregnancy in the rat. J. Hepatol. 38, 148–155. Arrese, M., Macias, R.I., Briz, O., Perez, M.J., Marin, J.J., 2008. Molecular pathogenesis of intrahepatic cholestasis of pregnancy. Expert Rev. Mol. Med. 10, e9. Bachs, L., Pares, A., Elena, M., Piera, C., Rodes, J., 1989. Comparison of rifampicin with phenobarbitone for treatment of pruritus in biliary cirrhosis. Lancet 1, 574–576. Bachs, L., Pares, A., Elena, M., Piera, C., Rodes, J., 1992. Effects of long-term rifampicin administration in primary biliary cirrhosis. Gastroenterology 102, 2077–2080. Bacq, Y., Sentilhes, L., Reyes, H.B., Glantz, A., Kondrackiene, J., Binder, T., Nicastri, P.L., Locatelli, A., Floreani, A., Hernandez, I., Di Martino, V., 2012. Efficacy of ursodeoxycholic acid in treating intrahepatic cholestasis of pregnancy: a meta-analysis. Gastroenterology 143, 1492–1501. Baghdasaryan, A., Fickert, P., Fuchsbichler, A., Silbert, D., Gumhold, J., Horl, G., Langner, C., Moustafa, T., Halilbasic, E., Claudel, T., Trauner, M., 2008. Role of hepatic phospholipids in development of liver injury in Mdr2 (Abcb4) knockout mice. Liver Int. 28, 948–958. Baghdasaryan, A., Claudel, T., Kosters, A., Gumhold, J., Silbert, D., Thuringer, A., Leski, K., Fickert, P., Karpen, S.J., Trauner, M., 2010. Curcumin improves sclerosing cholangitis in Mdr2/ mice by inhibition of cholangiocyte inflammatory response and portal myofibroblast proliferation. Gut 59, 521–530. Baghdasaryan, A., Claudel, T., Gumhold, J., Silbert, D., Adorini, L., Roda, A., Vecchiotti, S., Gonzalez, F.J., Schoonjans, K., Strazzabosco, M., et al, 2011. Dual farnesoid X receptor/TGR5 agonist INT-767 reduces liver injury in the Mdr2/ (Abcb4/) mouse cholangiopathy model by promoting biliary HCO output. Hepatology 54, 1303–1312. Balasubramaniyan, N., Ananthanarayanan, M., Suchy, F.J., 2012. Direct methylation of FXR by Set7/9, a lysine methyltransferase, regulates the expression of FXR target genes. Am. J. Physiol. Gastrointest. Liver Physiol. 302, G937–G947. Ballatori, N., 2011. Pleiotropic functions of the organic solute transporter Ostalpha–Ostbeta. Dig. Dis. 29, 13–17. Ballatori, N., Christian, W.V., Lee, J.Y., Dawson, P.A., Soroka, C.J., Boyer, J.L., Madejczyk, M.S., Li, N., 2005. OSTalpha–OSTbeta: a major basolateral bile acid and steroid transporter in human intestinal, renal, and biliary epithelia. Hepatology 42, 1270–1279. Ballatori, N., Fang, F., Christian, W.V., Li, N., Hammond, C.L., 2008. Ostalpha–Ostbeta is required for bile acid and conjugated steroid disposition in the intestine, kidney, and liver. Am. J. Physiol. Gastrointest. Liver Physiol. 295, G179–G186. Barbier, O., Duran-Sandoval, D., Pineda-Torra, I., Kosykh, V., Fruchart, J.C., Staels, B., 2003a. Peroxisome proliferator-activated receptor alpha induces hepatic expression of the human bile acid glucuronidating UDP-glucuronosyltransferase 2B4 enzyme. J. Biol. Chem. 278, 32852–32860. Barbier, O., Torra, I.P., Sirvent, A., Claudel, T., Blanquart, C., Duran-Sandoval, D., Kuipers, F., Kosykh, V., Fruchart, J.C., Staels, B., 2003b. FXR induces the UGT2B4 enzyme in hepatocytes: a potential mechanism of negative feedback control of FXR activity. Gastroenterology 124, 1926–1940. Barchetta, I., Carotti, S., Labbadia, G., Gentilucci, U.V., Muda, A.O., Angelico, F., Silecchia, G., Leonetti, F., Fraioli, A., Picardi, A., et al, 2012. Liver vitamin D receptor, CYP2R1, and CYP27A1 expression: relationship with liver histology and vitamin D3 levels in patients with nonalcoholic steatohepatitis or hepatitis C virus. Hepatology 56, 2180–2187. Barth, A., Klinger, G., Rost, M., 2003. Influence of ethinyloestradiol propanolsulphonate on serum bile acids in healthy volunteers. Exp. Toxicol. Pathol. 54, 381–386. Baskin-Bey, E.S., Huang, W., Ishimura, N., Isomoto, H., Bronk, S.F., Braley, K., Craig, R.W., Moore, D.D., Gores, G.J., 2006. Constitutive androstane receptor (CAR) ligand, TCPOBOP, attenuates Fas-induced murine liver injury by altering Bcl-2 proteins. Hepatology 44, 252–262. Beigneux, A.P., Moser, A.H., Shigenaga, J.K., Grunfeld, C., Feingold, K.R., 2000. The acute phase response is associated with retinoid X receptor repression in rodent liver. J. Biol. Chem. 275, 16390–16399. Beigneux, A.P., Moser, A.H., Shigenaga, J.K., Grunfeld, C., Feingold, K.R., 2002. Reduction in cytochrome P-450 enzyme expression is associated with repression of CAR (constitutive androstane receptor) and PXR (pregnane X receptor) in mouse liver during the acute phase response. Biochem. Biophys. Res. Commun. 293, 145–149. Bertolotti, M., Gabbi, C., Anzivino, C., Mitro, N., Godio, C., De Fabiani, E., Crestani, M., Del Puppo, M., Ricchi, M., Carulli, L., et al, 2006. Decreased hepatic expression of PPAR-gamma coactivator-1 in cholesterol cholelithiasis. Eur. J. Clin. Invest. 36, 170–175. Beuers, U., Bilzer, M., Chittattu, A., Kullak-Ublick, G.A., Keppler, D., Paumgartner, G., Dombrowski, F., 2001. Tauroursodeoxycholic acid inserts the apical conjugate export pump, Mrp2, into canalicular membranes and stimulates organic anion secretion by protein kinase C-dependent mechanisms in cholestatic rat liver. Hepatology 33, 1206–1216. Bloomer, J.R., Boyer, J.L., 1975. Phenobarbital effects in cholestatic liver diseases. Ann. Intern. Med. 82, 310–317. Bossard, R., Stieger, B., O’Neill, B., Fricker, G., Meier, P.J., 1993. Ethinylestradiol treatment induces multiple canalicular membrane transport alterations in rat liver. J. Clin. Invest. 91, 2714–2720. Boyer, J.L., Trauner, M., Mennone, A., Soroka, C.J., Cai, S.Y., Moustafa, T., Zollner, G., Lee, J.Y., Ballatori, N., 2006. Upregulation of a basolateral FXR-dependent bile acid efflux transporter OSTalpha–OSTbeta in cholestasis in humans and rodents. Am. J. Physiol. Gastrointest. Liver Physiol. 290, G1124–G1130. Brites, D., 2002. Intrahepatic cholestasis of pregnancy: changes in maternal–fetal bile acid balance and improvement by ursodeoxycholic acid. Ann. Hepatol. 1, 20–28. Byrne, J.A., Strautnieks, S.S., Mieli-Vergani, G., Higgins, C.F., Linton, K.J., Thompson, R.J., 2002. The human bile salt export pump: characterization of substrate specificity and identification of inhibitors. Gastroenterology 123, 1649–1658. Cancado, E.L., Leitao, R.M., Carrilho, F.J., Laudanna, A.A., 1998. Unexpected clinical remission of cholestasis after rifampicin therapy in patients with normal or slightly increased levels of gamma-glutamyl transpeptidase. Am. J. Gastroenterol. 93, 1510–1517. Cao, J., Gowri, P.M., Ganguly, T.C., Wood, M., Hyde, J.F., Talamantes, F., Vore, M., 2001. PRL, placental lactogen, and GH induce NA(+)/taurocholate- cotransporting polypeptide gene expression by activating signal transducer and activator of transcription-5 in liver cells. Endocrinology 142, 4212– 4222. Cao, J., Wood, M., Liu, Y., Hoffman, T., Hyde, J., Park-Sarge, O.K., Vore, M., 2004. Estradiol represses prolactin-induced expression of Na+/taurocholate cotransporting polypeptide in liver cells through estrogen receptor-alpha and signal transducers and activators of transcription 5a. Endocrinology 145, 1739–1749. Caroli-Bosc, F.X., Le Gall, P., Pugliese, P., Delabre, B., Caroli-Bosc, C., Demarquay, J.F., Delmont, J.P., Rampal, P., Montet, J.C., 2001. Role of fibrates and HMG- CoA reductase inhibitors in gallstone formation: epidemiological study in an unselected population. Dig. Dis. Sci. 46, 540–544. Carter, B.A., Shulman, R.J., 2007. Mechanisms of disease: update on the molecular etiology and fundamentals of parenteral nutrition associated cholestasis. Nat. Clin. Pract. Gastroenterol. Hepatol. 4, 277–287. Chai, J., Luo, D., Wu, X., Wang, H., He, Y., Li, Q., Zhang, Y., Chen, L., Peng, Z.H., Xiao, T., et al, 2011. Changes of organic anion transporter MRP4 and related nuclear receptors in human obstructive cholestasis. J. Gastrointest. Surg. 15, 996–1004. Chen, C., Staudinger, J.L., Klaassen, C.D., 2003a. Nuclear receptor, pregname X receptor, is required for induction of UDP-glucuronosyltranferases in mouse liver by pregnenolone-16 alpha-carbonitrile. Drug Metab. Dispos. 31, 908–915. Chen, Y., Ferguson, S.S., Negishi, M., Goldstein, J.A., 2003b. Identification of constitutive androstane receptor and glucocorticoid receptor binding sites in the CYP2C19 promoter. Mol. Pharmacol. 64, 316–324. Chen, Y., Ferguson, S.S., Negishi, M., Goldstein, J.A., 2004. Induction of human CYP2C9 by rifampicin, hyperforin, and phenobarbital is mediated by the pregnane X receptor. J. Pharmacol. Exp. Ther. 308, 495–501. Chen, Y., Song, X., Valanejad, L., Vasilenko, A., More, V., Qiu, X., Chen, W., Lai, Y., Slitt, A., Stoner, M., et al, 2012. Bile salt export pump is dysregulated with altered farnesoid X receptor isoform expression in patients with hepatocellular carcinoma. Hepatology 57, 1530–1541. Chignard, N., Mergey, M., Barbu, V., Finzi, L., Tiret, E., Paul, A., Housset, C., 2005. VPAC1 expression is regulated by FXR agonists in the human gallbladder epithelium. Hepatology 42, 549–557. Childs, S., Yeh, R.L., Georges, E., Ling, V., 1995. Identification of a sister gene to P-glycoprotein. Cancer Res. 55, 2029–2034. A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 69

Choi, M.K., Shin, H.J., Choi, Y.L., Deng, J.W., Shin, J.G., Song, I.S., 2011. Differential effect of genetic variants of Na(+)-taurocholate co-transporting polypeptide (NTCP) and organic anion-transporting polypeptide 1B1 (OATP1B1) on the uptake of HMG-CoA reductase inhibitors. Xenobiotica 41, 24–34. Chopra, A.R., Kommagani, R., Saha, P., Louet, J.F., Salazar, C., Song, J., Jeong, J., Finegold, M., Viollet, B., DeMayo, F., et al, 2011. Cellular energy depletion resets whole-body energy by promoting coactivator-mediated dietary fuel absorption. Cell Metab. 13, 35–43. Christian, W.V., Li, N., Hinkle, P.M., Ballatori, N., 2012. Beta-Subunit of the Ostalpha–Ostbeta organic solute transporter is required not only for heterodimerization and trafficking but also for function. J. Biol. Chem. 287, 21233–21243. Cohen, D.E., Leonard, M.R., Carey, M.C., 1994. In vitro evidence that phospholipid secretion into bile may be coordinated intracellularly by the combined actions of bile salts and the specific phosphatidylcholine transfer protein of liver. Biochemistry 33, 9975–9980. Crocenzi, F.A., Mottino, A.D., Cao, J., Veggi, L.M., Pozzi, E.J., Vore, M., Coleman, R., Roma, M.G., 2003. Estradiol-17beta-D-glucuronide induces endocytic internalization of Bsep in rats. Am. J. Physiol. Gastrointest. Liver Physiol. 285, G449–G459. Cui, Y.J., Aleksunes, L.M., Tanaka, Y., Goedken, M.J., Klaassen, C.D., 2009. Compensatory induction of liver efflux transporters in response to ANIT-induced liver injury is impaired in FXR-null mice. Toxicol. Sci. 110, 47–60. D’’Aldebert, E., Biyeyeme Bi Mve, M.J., Mergey, M., Wendum, D., Firrincieli, D., Coilly, A., Fouassier, L., Corpechot, C., Poupon, R., Housset, C., Chignard, N., 2009. Bile salts control the antimicrobial peptide cathelicidin through nuclear receptors in the human biliary epithelium. Gastroenterology 136, 1435– 1443. Dawson, P.A., Hubbert, M., Haywood, J., Craddock, A.L., Zerangue, N., Christian, W.V., Ballatori, N., 2005. The heteromeric organic solute transporter alpha– beta, Ostalpha–Ostbeta, is an ileal basolateral bile acid transporter. J. Biol. Chem. 280, 6960–6968. Dawson, P.A., Hubbert, M.L., Rao, A., 2010. Getting the mOST from OST: role of organic solute transporter, OSTalpha–OSTbeta, in bile acid and steroid metabolism. Biochim. Biophys. Acta 1801, 994–1004. Denk, G.U., Soroka, C.J., Takeyama, Y., Chen, W.S., Schuetz, J.D., Boyer, J.L., 2004. Multidrug resistance-associated protein 4 is up-regulated in liver but downregulated in kidney in obstructive cholestasis in the rat. J. Hepatol. 40, 585–591. Denson, L.A., Sturm, E., Echevarria, W., Zimmerman, T.L., Makishima, M., Mangelsdorf, D.J., Karpen, S.J., 2001. The orphan nuclear receptor, shp, mediates bile acid-induced inhibition of the rat bile acid transporter, ntcp. Gastroenterology 121, 140–147. Deuschle, U., Schuler, J., Schulz, A., Schluter, T., Kinzel, O., Abel, U., Kremoser, C., 2012. FXR controls the tumor suppressor NDRG2 and FXR agonists reduce liver tumor growth and metastasis in an orthotopic mouse xenograft model. PLoS ONE 7, e43044. Diao, L., Li, N., Brayman, T.G., Hotz, K.J., Lai, Y., 2010. Regulation of MRP2/ABCC2 and BSEP/ABCB11 expression in sandwich cultured human and rat hepatocytes exposed to inflammatory cytokines TNF-{alpha}, IL-6, and IL-1{beta}. J. Biol. Chem. 285, 31185–31192. Dixon, P.H., van Mil, S.W., Chambers, J., Strautnieks, S., Thompson, R.J., Lammert, F., Kubitz, R., Keitel, V., Glantz, A., Mattsson, L.A., et al, 2009. Contribution of variant alleles of ABCB11 to susceptibility to intrahepatic cholestasis of pregnancy. Gut 58, 537–544. Dombrowski, F., Stieger, B., Beuers, U., 2006. Tauroursodeoxycholic acid inserts the bile salt export pump into canalicular membranes of cholestatic rat liver. Lab. Invest. 86, 166–174. Donner, M.G., Schumacher, S., Warskulat, U., Heinemann, J., Haussinger, D., 2007. Obstructive cholestasis induces TNF-alpha- and IL-1-mediated periportal downregulation of Bsep and zonal regulation of Ntcp, Oatp1a4, and Oatp1b2. Am. J. Physiol. Gastrointest. Liver Physiol. 293, G1134–G1146. Eloranta, M.L., Hakli, T., Hiltunen, M., Helisalmi, S., Punnonen, K., Heinonen, S., 2003. Association of single nucleotide polymorphisms of the bile salt export pump gene with intrahepatic cholestasis of pregnancy. Scand. J. Gastroenterol. 38, 648–652. Eloranta, J.J., Jung, D., Kullak-Ublick, G.A., 2006. The human Na+-taurocholate cotransporting polypeptide gene is activated by glucocorticoid receptor and peroxisome proliferator-activated receptor-gamma coactivator-1alpha, and suppressed by bile acids via a small heterodimer partner-dependent mechanism. Mol. Endocrinol. 20, 65–79. Fan, L., Tu, X., Zhu, Y., Zhou, L., Pfeiffer, T., Feltens, R., Stoecker, W., Zhong, R., 2005. Genetic association of vitamin D receptor polymorphisms with autoimmune hepatitis and primary biliary cirrhosis in the Chinese. J. Gastroenterol. Hepatol. 20, 249–255. Fang, H.L., Strom, S.C., Cai, H., Falany, C.N., Kocarek, T.A., Runge-Morris, M., 2005. Regulation of human hepatic hydroxysteroid sulfotransferase gene expression by the peroxisome proliferator-activated receptor alpha transcription factor. Mol. Pharmacol. 67, 1257–1267. Fattinger, K., Funk, C., Pantze, M., Weber, C., Reichen, J., Stieger, B., Meier, P.J., 2001. The endothelin antagonist bosentan inhibits the canalicular bile salt export pump: a potential mechanism for hepatic adverse reactions. Clin. Pharmacol. Ther. 69, 223–231. Faubion, W.A., Guicciardi, M.E., Miyoshi, H., Bronk, S.F., Roberts, P.J., Svingen, P.A., Kaufmann, S.H., Gores, G.J., 1999. Toxic bile salts induce rodent hepatocyte apoptosis via direct activation of Fas. J. Clin. Invest. 103, 137–145. Fayard, E., Auwerx, J., Schoonjans, K., 2004. LRH-1: an orphan nuclear receptor involved in development, metabolism and steroidogenesis. Trends Cell Biol. 14, 250–260. Ferguson, S.S., Chen, Y., LeCluyse, E.L., Negishi, M., Goldstein, J.A., 2005. Human CYP2C8 is transcriptionally regulated by the nuclear receptors constitutive androstane receptor, pregnane X receptor, glucocorticoid receptor, and hepatic nuclear factor 4alpha. Mol. Pharmacol. 68, 747–757. Fickert, P., Zollner, G., Fuchsbichler, A., Stumptner, C., Pojer, C., Zenz, R., Lammert, F., Stieger, B., Meier, P.J., Zatloukal, K., et al, 2001. Effects of ursodeoxycholic and cholic acid feeding on hepatocellular transporter expression in mouse liver. Gastroenterology 121, 170–183. Fickert, P., Wagner, M., Marschall, H.U., Fuchsbichler, A., Zollner, G., Tsybrovskyy, O., Zatloukal, K., Liu, J., Waalkes, M.P., Cover, C., et al, 2006. 24- norUrsodeoxycholic acid is superior to ursodeoxycholic acid in the treatment of sclerosing cholangitis in Mdr2 (Abcb4) knockout mice. Gastroenterology 130, 465–481. Fiorucci, S., Clerici, C., Antonelli, E., Orlandi, S., Goodwin, B., Sadeghpour, B.M., Sabatino, G., Russo, G., Castellani, D., Willson, T.M., et al, 2005. Protective effects of 6-ethyl chenodeoxycholic acid, a farnesoid X receptor ligand, in estrogen-induced cholestasis. J. Pharmacol. Exp. Ther. 313, 604–612. Fouassier, L., Kinnman, N., Lefevre, G., Lasnier, E., Rey, C., Poupon, R., Elferink, R.P., Housset, C., 2002. Contribution of mrp2 in alterations of canalicular bile formation by the endothelin antagonist bosentan. J. Hepatol. 37, 184–191. Frankenberg, T., Rao, A., Chen, F., Haywood, J., Shneider, B.L., Dawson, P.A., 2006. Regulation of the mouse organic solute transporter alpha–beta, Ostalpha– Ostbeta, by bile acids. Am. J. Physiol. Gastrointest. Liver Physiol. 290, G912–G922. Fu, D., Wakabayashi, Y., Ido, Y., Lippincott-Schwartz, J., Arias, I.M., 2010. Regulation of bile canalicular network formation and maintenance by AMP- activated protein kinase and LKB1. J. Cell Sci. 123, 3294–3302. Funk, C., Ponelle, C., Scheuermann, G., Pantze, M., 2001. Cholestatic potential of troglitazone as a possible factor contributing to troglitazone-induced hepatotoxicity: in vivo and in vitro interaction at the canalicular bile salt export pump (Bsep) in the rat. Mol. Pharmacol. 59, 627–635. Gadaleta, R.M., Oldenburg, B., Willemsen, E.C., Spit, M., Murzilli, S., Salvatore, L., Klomp, L.W., Siersema, P.D., van Erpecum, K.J., van Mil, S.W., 2011. Activation of bile salt nuclear receptor FXR is repressed by pro-inflammatory cytokines activating NF-kappaB signaling in the intestine. Biochim. Biophys. Acta 1812, 851–858. Ganguly, T.C., O’Brien, M.L., Karpen, S.J., Hyde, J.F., Suchy, F.J., Vore, M., 1997. Regulation of the rat liver sodium-dependent bile acid cotransporter gene by prolactin. Mediation of transcriptional activation by Stat5. J. Clin. Invest. 99, 2906–2914. Gartung, C., Ananthanarayanan, M., Rahman, M.A., Schuele, S., Nundy, S., Soroka, C.J., Stolz, A., Suchy, F.J., Boyer, J.L., 1996. Down-regulation of expression and function of the rat liver Na+/bile acid cotransporter in extrahepatic cholestasis. Gastroenterology 110, 199–209. Geier, A., Dietrich, C.G., Gerloff, T., Haendly, J., Kullak-Ublick, G.A., Stieger, B., Meier, P.J., Matern, S., Gartung, C., 2003a. Regulation of basolateral organic anion transporters in ethinylestradiol-induced cholestasis in the rat. Biochim. Biophys. Acta 1609, 87–94. Geier, A., Dietrich, C.G., Voigt, S., Kim, S.K., Gerloff, T., Kullak-Ublick, G.A., Lorenzen, J., Matern, S., Gartung, C., 2003b. Effects of proinflammatory cytokines on rat organic anion transporters during toxic liver injury and cholestasis. Hepatology 38, 345–354. Geier, A., Dietrich, C.G., Voigt, S., Ananthanarayanan, M., Lammert, F., Schmitz, A., Trauner, M., Wasmuth, H.E., Boraschi, D., Balasubramaniyan, N., et al, 2005a. Cytokine-dependent regulation of hepatic organic anion transporter gene transactivators in mouse liver. Am. J. Physiol. Gastrointest. Liver Physiol. 289, G831–G841. 70 A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76

Geier, A., Zollner, G., Dietrich, C.G., Wagner, M., Fickert, P., Denk, H., van Rooijen, N., Matern, S., Gartung, C., Trauner, M., 2005b. Cytokine-independent repression of rodent Ntcp in obstructive cholestasis. Hepatology 41, 470–477. Geier, A., Martin, I.V., Dietrich, C.G., Balasubramaniyan, N., Strauch, S., Suchy, F.J., Gartung, C., Trautwein, C., Ananthanarayanan, M., 2008. Hepatocyte nuclear factor-4alpha is a central transactivator of the mouse Ntcp gene. Am. J. Physiol. Gastrointest. Liver Physiol. 295, G226–G233. Gerbal-Chaloin, S., Daujat, M., Pascussi, J.M., Pichard-Garcia, L., Vilarem, M.J., Maurel, P., 2002. Transcriptional regulation of CYP2C9 gene. Role of glucocorticoid receptor and constitutive androstane receptor. J. Biol. Chem. 277, 209–217. Gerloff, T., Stieger, B., Hagenbuch, B., Madon, J., Landmann, L., Roth, J., Hofmann, A.F., Meier, P.J., 1998. The sister of P-glycoprotein represents the canalicular bile salt export pump of mammalian liver. J. Biol. Chem. 273, 10046–10050. Gerloff, T., Geier, A., Roots, I., Meier, P.J., Gartung, C., 2002. Functional analysis of the rat bile salt export pump gene promoter. Eur. J. Biochem. 269, 3495– 3503. Ghonem, N.S., Boyer, J.L., 2013. Fibrates as adjuvant therapy for chronic cholestatic liver disease – it’s time has come. Hepatology 57, 1691–1693. Ghose, R., Mulder, J., von Furstenberg, R.J., Thevananther, S., Kuipers, F., Karpen, S.J., 2007. Rosiglitazone attenuates suppression of RXRalpha-dependent gene expression in inflamed liver. J. Hepatol. 46, 115–123. Glantz, A., Marschall, H.U., Lammert, F., Mattsson, L.A., 2005. Intrahepatic cholestasis of pregnancy: a randomized controlled trial comparing dexamethasone and ursodeoxycholic acid. Hepatology 42, 1399–1405. Glantz, A., Reilly, S.J., Benthin, L., Lammert, F., Mattsson, L.A., Marschall, H.U., 2008. Intrahepatic cholestasis of pregnancy: amelioration of pruritus by UDCA is associated with decreased progesterone disulphates in urine. Hepatology 47, 544–551. Gnerre, C., Blattler, S., Kaufmann, M.R., Looser, R., Meyer, U.A., 2004. Regulation of CYP3A4 by the bile acid receptor FXR: evidence for functional binding sites in the CYP3A4 gene. Pharmacogenetics 14, 635–645. Goldstein, J.A., de Morais, S.M., 1994. Biochemistry and molecular biology of the human CYP2C subfamily. Pharmacogenetics 4, 285–299. Goodwin, B., Hodgson, E., Liddle, C., 1999. The orphan human pregnane X receptor mediates the transcriptional activation of CYP3A4 by rifampicin through a distal enhancer module. Mol. Pharmacol. 56, 1329–1339. Goodwin, B., Hodgson, E., D’Costa, D.J., Robertson, G.R., Liddle, C., 2002. Transcriptional regulation of the human CYP3A4 gene by the constitutive androstane receptor. Mol. Pharmacol. 62, 359–365. Graf, D., Kurz, A.K., Fischer, R., Reinehr, R., Haussinger, D., 2002. Taurolithocholic acid-3 sulfate induces CD95 trafficking and apoptosis in a c-Jun N-terminal kinase-dependent manner. Gastroenterology 122, 1411–1427. Green, R.M., Beier, D., Gollan, J.L., 1996. Regulation of hepatocyte bile salt transporters by endotoxin and inflammatory cytokines in rodents. Gastroenterology 111, 193–198. Guicciardi, M.E., Gores, G.J., 2002. Ursodeoxycholic acid cytoprotection: dancing with death receptors and survival pathways. Hepatology 35, 971–973. Hagenbuch, B., Stieger, B., Foguet, M., Lubbert, H., Meier, P.J., 1991. Functional expression cloning and characterization of the hepatocyte Na+/bile acid cotransport system. Proc. Natl. Acad. Sci. USA 88, 10629–10633. Halilbasic, E., Fiorotto, R., Fickert, P., Marschall, H.U., Moustafa, T., Spirli, C., Fuchsbichler, A., Gumhold, J., Silbert, D., Zatloukal, K., et al, 2009. Side chain structure determines unique physiologic and therapeutic properties of norursodeoxycholic acid in Mdr2/ mice. Hepatology 49, 1972–1981. Halmos, B., Szalay, F., Cserniczky, T., Nemesanszky, E., Lakatos, P., Barlage, S., Schmitz, G., Romics, L., Csaszar, A., 2000. Association of primary biliary cirrhosis with vitamin D receptor BsmI genotype polymorphism in a Hungarian population. Dig. Dis. Sci. 45, 1091–1095. Hansen, S.K., Parrizas, M., Jensen, M.L., Pruhova, S., Ek, J., Boj, S.F., Johansen, A., Maestro, M.A., Rivera, F., Eiberg, H., et al, 2002. Genetic evidence that HNF- 1alpha-dependent transcriptional control of HNF-4alpha is essential for human pancreatic beta cell function. J. Clin. Invest. 110, 827–833. Harada, K., Nakanuma, Y., 2010. Biliary innate immunity: function and modulation. Mediators Inflamm. 2010. http://dx.doi.org/10.1155/2010/373878. Harada, K., Isse, K., Kamihira, T., Shimoda, S., Nakanuma, Y., 2005. Th1 cytokine-induced downregulation of PPARgamma in human biliary cells relatesto cholangitis in primary biliary cirrhosis. Hepatology 41, 1329–1338. Hartmann, G., Cheung, A.K., Piquette-Miller, M., 2002. Inflammatory cytokines, but not bile acids, regulate expression of murine hepatic anion transporters in endotoxemia. J. Pharmacol. Exp. Ther. 303, 273–281. Hayashi, H., Takada, T., Suzuki, H., Onuki, R., Hofmann, A.F., Sugiyama, Y., 2005. Transport by vesicles of glycine- and taurine-conjugated bile salts and taurolithocholate 3-sulfate: a comparison of human BSEP with rat Bsep. Biochim. Biophys. Acta 1738, 54–62. Hayhurst, G.P., Lee, Y.H., Lambert, G., Ward, J.M., Gonzalez, F.J., 2001. Hepatocyte nuclear factor 4alpha (nuclear receptor 2A1) is essential for maintenance of hepatic gene expression and lipid homeostasis. Mol. Cell. Biol. 21, 1393–1403. Hazra, S., Miyahara, T., Rippe, R.A., Tsukamoto, H., 2004a. PPAR gamma and hepatic stellate cells. Comp. Hepatol. 3 (Suppl. 1), S7. Hazra, S., Xiong, S., Wang, J., Rippe, R.A., Krishna, V., Chatterjee, K., Tsukamoto, H., 2004b. Peroxisome proliferator-activated receptor gamma induces a phenotypic switch from activated to quiescent hepatic stellate cells. J. Biol. Chem. 279, 11392–11401. Hempfling, W., Grunhage, F., Dilger, K., Reichel, C., Beuers, U., Sauerbruch, T., 2003. Pharmacokinetics and pharmacodynamic action of budesonide in early- and late-stage primary biliary cirrhosis. Hepatology 38, 196–202. Henkel, A.S., Kavesh, M.H., Kriss, M.S., Dewey, A.M., Rinella, M.E., Green, R.M., 2011. Hepatic overexpression of abcb11 promotes hypercholesterolemia and obesity in mice. Gastroenterology 141, 1404–1411, 1411 e1401–1402. Hirschfield, G.M., Mason, A.L., Gordon, S.C., Luketic, V.A., Mayo, M., Vincent, V., Lindor, K.D., Pares, A., Kowdley, K.V., Trauner, M., et al. (2011). A long term safety extension trial of the farnesoid X receptor (FXR) agonist obeticholic acid (OCA) and UDCA in primary biliary cirrhosis (PBC). In: The 62nd Annual Meeting of the American Association for the Study of Liver Diseases: The Liver Meeting 54, 429A (Hepatology Supplement). Ho, R.H., Leake, B.F., Roberts, R.L., Lee, W., Kim, R.B., 2004. Ethnicity-dependent polymorphism in Na+-taurocholate cotransporting polypeptide (SLC10A1) reveals a domain critical for bile acid substrate recognition. J. Biol. Chem. 279, 7213–7222. Ho, R.H., Leake, B.F., Kilkenny, D.M., Meyer, Zu., Schwabedissen, H.E., Glaeser, H., Kroetz, D.L., Kim, R.B., 2010. Polymorphic variants in the human bile salt export pump (BSEP; ABCB11): functional characterization and interindividual variability. Pharmacogenet. Genomics 20, 45–57. Hofmann, A.F., 1994. Pharmacology of ursodeoxycholic acid, an enterohepatic drug. Scand. J. Gastroenterol. Suppl. 204, 1–15. Hofmann, A.F., 1999. Bile acids: the good, the bad, and the ugly. News Physiol. Sci. 14, 24–29. Hojo, Y., Shiraki, A., Tsuchiya, T., Shimamoto, K., Ishii, Y., Suzuki, K., Shibutani, M., Mitsumori, K., 2012. Liver tumor promoting effect of etofenprox in rats and its possible mechanism of action. J. Toxicol. Sci. 37, 297–306. Honda, A., Ikegami, T., Nakamuta, M., Miyazaki, T., Iwamoto, J., Hirayama, T., Saito, Y., Takikawa, H., Imawari, M., Matsuzaki, Y., 2013. Anticholestatic effects of bezafibrate in patients with primary biliary cirrhosis treated with ursodeoxycholic acid. Hepatology 57, 1931–1941. Honjo, Y., Sasaki, S., Kobayashi, Y., Misawa, H., Nakamura, H., 2006. 1,25-Dihydroxyvitamin D3 and its receptor inhibit the chenodeoxycholic acid- dependent transactivation by farnesoid X receptor. J. Endocrinol. 188, 635–643. Honkakoski, P., Zelko, I., Sueyoshi, T., Negishi, M., 1998. The nuclear orphan receptor CAR-retinoid X receptor heterodimer activates the phenobarbital- responsive enhancer module of the CYP2B gene. Mol. Cell. Biol. 18, 5652–5658. Huang, W., Zhang, J., Chua, S.S., Qatanani, M., Han, Y., Granata, R., Moore, D.D., 2003. Induction of bilirubin clearance by the constitutive androstane receptor (CAR). Proc. Natl. Acad. Sci. USA 100, 4156–4161. Huang, W., Zhang, J., Moore, D.D., 2004. A traditional herbal medicine enhances bilirubin clearance by activating the nuclear receptor CAR. J. Clin. Invest. 113, 137–143. Huang, W., Zhang, J., Washington, M., Liu, J., Parant, J.M., Lozano, G., Moore, D.D., 2005. Xenobiotic stress induces hepatomegaly and liver tumors via the nuclear receptor constitutive androstane receptor. Mol. Endocrinol. 19, 1646–1653. Huang, W., Ma, K., Zhang, J., Qatanani, M., Cuvillier, J., Liu, J., Dong, B., Huang, X., Moore, D.D., 2006. Nuclear receptor-dependent bile acid signaling is required for normal liver regeneration. Science 312, 233–236. A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 71

Itakura, J., Izumi, N., Nishimura, Y., Inoue, K., Ueda, K., Nakanishi, H., Tsuchiya, K., Hamano, K., Asahina, Y., Kurosaki, M., et al, 2004. Prospective randomized crossover trial of combination therapy with bezafibrate and UDCA for primary biliary cirrhosis. Hepatol. Res. 29, 216–222. Itoh, K., Chiba, T., Takahashi, S., Ishii, T., Igarashi, K., Katoh, Y., Oyake, T., Hayashi, N., Satoh, K., Hatayama, I., et al, 1997. An Nrf2/small Maf heterodimer mediates the induction of phase II detoxifying enzyme genes through antioxidant response elements. Biochem. Biophys. Res. Commun. 236, 313–322. Jansen, P.L., Strautnieks, S.S., Jacquemin, E., Hadchouel, M., Sokal, E.M., Hooiveld, G.J., Koning, J.H., De Jager-Krikken, A., Kuipers, F., Stellaard, F., et al, 1999. Hepatocanalicular bile salt export pump deficiency in patients with progressive familial intrahepatic cholestasis. Gastroenterology 117, 1370–1379. Janvilisri, T., Shahi, S., Venter, H., Balakrishnan, L., van Veen, H.W., 2005. Arginine-482 is not essential for transport of antibiotics, primary bile acids and unconjugated sterols by the human breast cancer resistance protein (ABCG2). Biochem. J. 385, 419–426. Jazrawi, R.P., de Caestecker, J.S., Goggin, P.M., Britten, A.J., Joseph, A.E., Maxwell, J.D., Northfield, T.C., 1994. Kinetics of hepatic bile acid handling in cholestatic liver disease: effect of ursodeoxycholic acid. Gastroenterology 106, 134–142. Jung, D., Kullak-Ublick, G.A., 2003. Hepatocyte nuclear factor 1 alpha: a key mediator of the effect of bile acids on gene expression. Hepatology 37, 622–631. Jung, D., Fried, M., Kullak-Ublick, G.A., 2002. Human apical sodium-dependent bile salt transporter gene (SLC10A2) is regulated by the peroxisome proliferator-activated receptor alpha. J. Biol. Chem. 277, 30559–30566. Jung, D., Fantin, A.C., Scheurer, U., Fried, M., Kullak-Ublick, G.A., 2004a. Human ileal bile acid transporter gene ASBT (SLC10A2) is transactivated by the glucocorticoid receptor. Gut 53, 78–84. Jung, D., Hagenbuch, B., Fried, M., Meier, P.J., Kullak-Ublick, G.A., 2004b. Role of liver-enriched transcription factors and nuclear receptors in regulating the human, mouse, and rat NTCP gene. Am. J. Physiol. Gastrointest. Liver Physiol. 286, G752–G761. Kagawa, T., Watanabe, N., Mochizuki, K., Numari, A., Ikeno, Y., Itoh, J., Tanaka, H., Arias, I.M., Mine, T., 2008. Phenotypic differences in PFIC2 and BRIC2 correlate with protein stability of mutant Bsep and impaired taurocholate secretion in MDCK II cells. Am. J. Physiol. Gastrointest. Liver Physiol. 294, G58–G67. Kaimal, R., Song, X., Yan, B., King, R., Deng, R., 2009. Differential modulation of farnesoid X receptor signaling pathway by the thiazolidinediones.J. Pharmacol. Exp. Ther. 330, 125–134. Kanaya, E., Shiraki, T., Jingami, H., 2004. The nuclear bile acid receptor FXR is activated by PGC-1alpha in a ligand-dependent manner. Biochem. J. 382, 913– 921. Kanda, T., Yokosuka, O., Imazeki, F., Saisho, H., 2003. Bezafibrate treatment: a new medical approach for PBC patients? J. Gastroenterol. 38, 573–578. Karpen, S.J., Sun, A.Q., Kudish, B., Hagenbuch, B., Meier, P.J., Ananthanarayanan, M., Suchy, F.J., 1996. Multiple factors regulate the rat liver basolateral sodium-dependent bile acid cotransporter gene promoter. J. Biol. Chem. 271, 15211–15221. Kast, H.R., Goodwin, B., Tarr, P.T., Jones, S.A., Anisfeld, A.M., Stoltz, C.M., Tontonoz, P., Kliewer, S., Willson, T.M., Edwards, P.A., 2002. Regulation of multidrug resistance-associated protein 2 (ABCC2) by the nuclear receptors pregnane X receptor, farnesoid X-activated receptor, and constitutive androstane receptor. J. Biol. Chem. 277, 2908–2915. Kawamata, Y., Fujii, R., Hosoya, M., Harada, M., Yoshida, H., Miwa, M., Fukusumi, S., Habata, Y., Itoh, T., Shintani, Y., et al, 2003. A G protein-coupled receptor responsive to bile acids. J. Biol. Chem. 278, 9435–9440. Keitel, V., Vogt, C., Haussinger, D., Kubitz, R., 2006. Combined mutations of canalicular transporter proteins cause severe intrahepatic cholestasis of pregnancy. Gastroenterology 131, 624–629. Keitel, V., Reinehr, R., Reich, M., Sommerfeld, A., Cupisti, K., Knoefel, W.T., Haussinger, D. (2011). The membrane-bound bile acid receptor TGR5 (Gpbar-1) is highly expressed in intrahepatic cholangiocarcinoma. In: The 62nd Annual Meeting of the American Association for the Study of Liver Diseases: The Liver Meeting 54 (Hepatology Supplement). Keppler, D., Konig, J., Buchler, M., 1997. The canalicular multidrug resistance protein, cMRP/MRP2, a novel conjugate export pump expressed in the apical membrane of hepatocytes. Adv. Enzyme Regul. 37, 321–333. Kerr, T.A., Saeki, S., Schneider, M., Schaefer, K., Berdy, S., Redder, T., Shan, B., Russell, D.W., Schwarz, M., 2002. Loss of nuclear receptor SHP impairs but does not eliminate negative feedback regulation of bile acid synthesis. Dev. Cell 2, 713–720. Khan, A.A., Chow, E.C., Porte, R.J., Pang, K.S., Groothuis, G.M., 2009. Expression and regulation of the bile acid transporter, OSTalpha–OSTbeta in rat and human intestine and liver. Biopharm. Drug Dispos. 30, 241–258. Kiyosawa, N., Kwekel, J.C., Burgoon, L.D., Williams, K.J., Tashiro, C., Chittim, B., Zacharewski, T.R., 2008. O, p0-DDT elicits PXR/CAR-, not ER-, mediated responses in the immature ovariectomized rat liver. Toxicol. Sci. 101, 350–363. Knisely, A.S., Portmann, B.C., 2006. Deficiency of BSEP in PFIC with hepatocellular malignancy. Pediatr. Transplant. 10, 644–645, author reply 646. Knisely, A.S., Strautnieks, S.S., Meier, Y., Stieger, B., Byrne, J.A., Portmann, B.C., Bull, L.N., Pawlikowska, L., Bilezikci, B., Ozcay, F., et al, 2006. Hepatocellular carcinoma in ten children under five years of age with bile salt export pump deficiency. Hepatology 44, 478–486. Kondrackiene, J., Beuers, U., Kupcinskas, L., 2005. Efficacy and safety of ursodeoxycholic acid versus cholestyramine in intrahepatic cholestasis of pregnancy. Gastroenterology 129, 894–901. Konig, J., Cui, Y., Nies, A.T., Keppler, D., 2000. A novel human organic anion transporting polypeptide localized to the basolateral hepatocyte membrane. Am. J. Physiol. Gastrointest. Liver Physiol. 278, G156–G164. Kowdley, K.V., Luketic, V.A., Jones, D.E., Chapman, R.W., Burroughs, A., Hirschfield, G.M., Poupon, R., Schramm, C., Vincent, C., Rust, C., et al. (2011). The first new monotherapy therapeutic PBC study in a decade? An international study evaluating the farnesoid X receptor agonist obeticholic acid in PBC. In: The 62nd Annual Meeting of the American Association for the Study of Liver Diseases: The Liver Meeting 54, 416A (Hepatology Supplement). Krahenbuhl, S., Talos, C., Fischer, S., Reichen, J., 1994. Toxicity of bile acids on the electron transport chain of isolated rat liver mitochondria. Hepatology 19, 471–479. Kremer, A.E., Martens, J.J., Kulik, W., Rueff, F., Kuiper, E.M., van Buuren, H.R., van Erpecum, K.J., Kondrackiene, J., Prieto, J., Rust, C., et al, 2010. Lysophosphatidic acid is a potential mediator of cholestatic pruritus. Gastroenterology 139, 1008–1018, 1018 e1001. Kremer, A.E., van Dijk, R., Leckie, P., Schaap, F.G., Kuiper, E.M., Mettang, T., Reiners, K.S., Raap, U., van Buuren, H.R., van Erpecum, K.J., et al, 2012. Serum autotaxin is increased in pruritus of cholestasis, but not of other origin, and responds to therapeutic interventions. Hepatology 56, 1391–1400. Krylova, I.N., Sablin, E.P., Moore, J., Xu, R.X., Waitt, G.M., MacKay, J.A., Juzumiene, D., Bynum, J.M., Madauss, K., Montana, V., et al, 2005. Structural analyses reveal phosphatidyl inositols as ligands for the NR5 orphan receptors SF-1 and LRH-1. Cell 120, 343–355. Kubitz, R., Sutfels, G., Kuhlkamp, T., Kolling, R., Haussinger, D., 2004. Trafficking of the bile salt export pump from the golgi to the canalicular membrane is regulated by the p38 MAP kinase. Gastroenterology 126, 541–553. Kubitz, R., Keitel, V., Scheuring, S., Kohrer, K., Haussinger, D., 2006. Benign recurrent intrahepatic cholestasis associated with mutations of the bile salt export pump. J. Clin. Gastroenterol. 40, 171–175. Kublbeck, J., Jyrkkarinne, J., Molnar, F., Kuningas, T., Patel, J., Windshugel, B., Nevalainen, T., Laitinen, T., Sippl, W., Poso, A., Honkakoski, P., 2011. New in vitro tools to study human constitutive androstane receptor (CAR) biology: discovery and comparison of human CAR inverse agonists. Mol. Pharm. 8, 2424– 2433. Kullak-Ublick, G.A., Glasa, J., Boker, C., Oswald, M., Grutzner, U., Hagenbuch, B., Stieger, B., Meier, P.J., Beuers, U., Kramer, W., et al, 1997. Chlorambucil- taurocholate is transported by bile acid carriers expressed in human hepatocellular carcinomas. Gastroenterology 113, 1295–1305. Kullak-Ublick, G.A., Ismair, M.G., Stieger, B., Landmann, L., Huber, R., Pizzagalli, F., Fattinger, K., Meier, P.J., Hagenbuch, B., 2001. Organic anion-transporting polypeptide B (OATP-B) and its functional comparison with three other OATPs of human liver. Gastroenterology 120, 525–533. Kurihara, T., Niimi, A., Maeda, A., Shigemoto, M., Yamashita, K., 2000. Bezafibrate in the treatment of primary biliary cirrhosis: comparison with ursodeoxycholic acid. Am. J. Gastroenterol. 95, 2990–2992. Kurihara, T., Maeda, A., Shigemoto, M., Yamashita, K., Hashimoto, E., 2002. Investigation into the efficacy of bezafibrate against primary biliary cirrhosis, with histological references from cases receiving long term monotherapy. Am. J. Gastroenterol. 97, 212–214. 72 A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76

Kurz, A.K., Graf, D., Schmitt, M., Vom Dahl, S., Haussinger, D., 2001. Tauroursodesoxycholate-induced choleresis involves p38(MAPK) activation and translocation of the bile salt export pump in rats. Gastroenterology 121, 407–419. Lacaille, F., Paradis, K., 1993. The immunosuppressive effect of ursodeoxycholic acid: a comparative in vitro study on human peripheral blood mononuclear cells. Hepatology 18, 165–172. Lam, P., Wang, R., Ling, V., 2005. Bile acid transport in sister of P-glycoprotein (ABCB11) knockout mice. Biochemistry 44, 12598–12605. Lamireau, T., Bouchard, G., Yousef, I.M., Clouzeau-Girard, H., Rosenbaum, J., Desmouliere, A., Tuchweber, B., 2007. Dietary lecithin protects against cholestatic liver disease in cholic acid-fed Abcb4-deficient mice. Pediatr. Res. 61, 185–190. Lan, T., Haywood, J., Rao, A., Dawson, P.A., 2011. Molecular mechanisms of altered bile acid homeostasis in organic solute transporter-alpha knockout mice. Dig. Dis. 29, 18–22. Lan, T., Rao, A., Haywood, J., Kock, N.D., Dawson, P.A., 2012. Mouse organic solute transporter alpha deficiency alters FGF15 expression and bile acid metabolism. J. Hepatol. 57, 359–365. Landrier, J.F., Eloranta, J.J., Vavricka, S.R., Kullak-Ublick, G.A., 2006. The nuclear receptor for bile acids, FXR, transactivates human organic solute transporter- alpha and -beta genes. Am. J. Physiol. Gastrointest. Liver Physiol. 290, G476–G485. Lang, C., Meier, Y., Stieger, B., Beuers, U., Lang, T., Kerb, R., Kullak-Ublick, G.A., Meier, P.J., Pauli-Magnus, C., 2007. Mutations and polymorphisms in the bile salt export pump and the multidrug resistance protein 3 associated with drug-induced liver injury. Pharmacogenet. Genomics 17, 47–60. Lazaridis, K.N., Gores, G.J., Lindor, K.D., 2001. Ursodeoxycholic acid ‘mechanisms of action and clinical use in hepatobiliary disorders’. J. Hepatol. 35, 134– 146. Le Vee, M., Gripon, P., Stieger, B., Fardel, O., 2008. Down-regulation of organic anion transporter expression in human hepatocytes exposed to the proinflammatory cytokine interleukin 1beta. Drug Metab. Dispos. 36, 217–222. Lee, J., Boyer, J.L., 2000. Molecular alterations in hepatocyte transport mechanisms in acquired cholestatic liver disorders. Semin. Liver Dis. 20, 373–384. Lee, Y.K., Dell, H., Dowhan, D.H., Hadzopoulou-Cladaras, M., Moore, D.D., 2000. The orphan nuclear receptor SHP inhibits hepatocyte nuclear factor 4 and retinoid X receptor transactivation: two mechanisms for repression. Mol. Cell. Biol. 20, 187–195. Lee, Y.H., Coonrod, S.A., Kraus, W.L., Jelinek, M.A., Stallcup, M.R., 2005. Regulation of coactivator complex assembly and function by protein arginine methylation and demethylimination. Proc. Natl. Acad. Sci. USA 102, 3611–3616. Lee, H., Zhang, Y., Lee, F.Y., Nelson, S.F., Gonzalez, F.J., Edwards, P.A., 2006. FXR regulates organic solute transporters alpha and beta in the adrenal gland, kidney, and intestine. J. Lipid Res. 47, 201–214. Lee, Y.K., Schmidt, D.R., Cummins, C.L., Choi, M., Peng, L., Zhang, Y., Goodwin, B., Hammer, R.E., Mangelsdorf, D.J., Kliewer, S.A., 2008. Liver receptor homolog- 1 regulates bile acid homeostasis but is not essential for feedback regulation of bile acid synthesis. Mol. Endocrinol. 22, 1345–1356. Leuschner, M., Maier, K.P., Schlichting, J., Strahl, S., Herrmann, G., Dahm, H.H., Ackermann, H., Happ, J., Leuschner, U., 1999. Oral budesonide and ursodeoxycholic acid for treatment of primary biliary cirrhosis: results of a prospective double-blind trial. Gastroenterology 117, 918–925. Levy, C., Peter, J.A., Nelson, D.R., Keach, J., Petz, J., Cabrera, R., Clark, V., Firpi, R.J., Morelli, G., Soldevila-Pico, C., Lindor, K., 2011. Pilot study: fenofibrate for patients with primary biliary cirrhosis and an incomplete response to ursodeoxycholic acid. Aliment. Pharmacol. Ther. 33, 235–242. Li, D., Zimmerman, T.L., Thevananther, S., Lee, H.Y., Kurie, J.M., Karpen, S.J., 2002. Interleukin-1 beta-mediated suppression of RXR:RAR transactivation of the Ntcp promoter is JNK-dependent. J. Biol. Chem. 277, 31416–31422. Li, N., Cui, Z., Fang, F., Lee, J.Y., Ballatori, N., 2007. Heterodimerization, trafficking and membrane topology of the two proteins, Ost alpha and Ost beta, that constitute the organic solute and steroid transporter. Biochem. J. 407, 363–372. Li, J., Gong, Y.M., Wu, J., Wu, W.J., Cai, W., 2012. Anti-tumor necrosis factor-alpha monoclonal antibody alleviates parenteral nutrition-associated liver disease in mice. JPEN J. Parenter. Enteral Nutr. 36, 219–225. Lindblad, L., Lundholm, K., Schersten, T., 1977. Bile acid concentrations in systemic and portal serum in presumably normal man and in cholestatic and cirrhotic conditions. Scand. J. Gastroenterol. 12, 395–400. Lindor, K.D., Kowdley, K.V., Luketic, V.A., Harrison, M.E., McCashland, T., Befeler, A.S., Harnois, D., Jorgensen, R., Petz, J., Keach, J., et al, 2009. High-dose ursodeoxycholic acid for the treatment of primary sclerosing cholangitis. Hepatology 50, 808–814. Liu, Y., Binz, J., Numerick, M.J., Dennis, S., Luo, G., Desai, B., MacKenzie, K.I., Mansfield, T.A., Kliewer, S.A., Goodwin, B., Jones, S.A., 2003. Hepatoprotection by the farnesoid X receptor agonist GW4064 in rat models of intra- and extrahepatic cholestasis. J. Clin. Invest. 112, 1678–1687. Lu, Y., Zhang, Z., Xiong, X., Wang, X., Li, J., Shi, G., Yang, J., Zhang, X., Zhang, H., Hong, J., et al, 2012. Glucocorticoids promote hepatic cholestasis in mice by inhibiting the transcriptional activity of the farnesoid X receptor. Gastroenterology 143 (1630–1640), e1638. Makishima, M., Okamoto, A.Y., Repa, J.J., Tu, H., Learned, R.M., Luk, A., Hull, M.V., Lustig, K.D., Mangelsdorf, D.J., Shan, B., 1999. Identification of a nuclear receptor for bile acids. Science 284, 1362–1365. Maloney, P.R., Parks, D.J., Haffner, C.D., Fivush, A.M., Chandra, G., Plunket, K.D., Creech, K.L., Moore, L.B., Wilson, J.G., Lewis, M.C., et al, 2000. Identification of a chemical tool for the orphan nuclear receptor FXR. J. Med. Chem. 43, 2971–2974. Marrapodi, M., Chiang, J.Y., 2000. Peroxisome proliferator-activated receptor alpha (PPARalpha) and agonist inhibit cholesterol 7alpha-hydroxylase gene (CYP7A1) transcription. J. Lipid Res. 41, 514–520. Marschall, H.U., Wagner, M., Zollner, G., Fickert, P., Diczfalusy, U., Gumhold, J., Silbert, D., Fuchsbichler, A., Benthin, L., Grundstrom, R., et al, 2005. Complementary stimulation of hepatobiliary transport and detoxification systems by rifampicin and ursodeoxycholic acid in humans. Gastroenterology 129, 476–485. Maruyama, T., Miyamoto, Y., Nakamura, T., Tamai, Y., Okada, H., Sugiyama, E., Nakamura, T., Itadani, H., Tanaka, K., 2002. Identification of membrane-type receptor for bile acids (M-BAR). Biochem. Biophys. Res. Commun. 298, 714–719. Mason, A.L., Luketic, V.A., Lindor, K.D., Hirschfield, G.M., Gordon, S.C., Mayo, M.J., Kowdley, K.V., Pares, A., Trauner, M., Sciacca, C.I., et al. (2010). Farnesoid-X receptor agonists: a new class of drugs for the treatment of PBC? An international study evaluating the addition of obeticholic acid (INT-747) to ursodeoxycholic acid. In: The 61th Annual Meeting of the American Association for the Study of Liver Diseases: The Liver Meeting 52, 357A (Hepatology Supplement). Mataki, C., Magnier, B.C., Houten, S.M., Annicotte, J.S., Argmann, C., Thomas, C., Overmars, H., Kulik, W., Metzger, D., Auwerx, J., Schoonjans, K., 2007. Compromised intestinal lipid absorption in mice with a liver-specific deficiency of liver receptor homolog 1. Mol. Cell. Biol. 27, 8330–8339. Matsumoto, T., Miyazaki, H., Nakahashi, Y., Hirohara, J., Seki, T., Inoue, K., Okazaki, K., 2004. Multidrug resistance3 is in situ detected in the liver of patients with primary biliary cirrhosis, and induced in human hepatoma cells by bezafibrate. Hepatol. Res. 30, 125–136. Mazzella, G., Rizzo, N., Azzaroli, F., Simoni, P., Bovicelli, L., Miracolo, A., Simonazzi, G., Colecchia, A., Nigro, G., Mwangemi, C., et al, 2001. Ursodeoxycholic acid administration in patients with cholestasis of pregnancy: effects on primary bile acids in babies and mothers. Hepatology 33, 504–508. Medina, J.F., 2011. Role of the anion exchanger 2 in the pathogenesis and treatment of primary biliary cirrhosis. Dig. Dis. 29, 103–112. Medina, J.F., Martinez, A., Vazquez, J.J., Prieto, J., 1997. Decreased anion exchanger 2 immunoreactivity in the liver of patients with primary biliary cirrhosis. Hepatology 25, 12–17. Mehlmann, J.F., Crawley, M.L., Lundquist, J.T.T., Unwalla, R.J., Harnish, D.C., Evans, M.J., Kim, C.Y., Wrobel, J.E., Mahaney, P.E., 2009. Pyrrole[2,3-d]azepino compounds as agonists of the farnesoid X receptor (FXR). Bioorg. Med. Chem. Lett. 19, 5289–5292. Meier, P.J., Stieger, B., 2002. Bile salt transporters. Annu. Rev. Physiol. 64, 635–661. Meier, Y., Zodan, T., Lang, C., Zimmermann, R., Kullak-Ublick, G.A., Meier, P.J., Stieger, B., Pauli-Magnus, C., 2008. Increased susceptibility for intrahepatic cholestasis of pregnancy and contraceptive-induced cholestasis in carriers of the 1331T>C polymorphism in the bile salt export pump. World J. Gastroenterol. 14, 38–45. Mennone, A., Soroka, C.J., Cai, S.Y., Harry, K., Adachi, M., Hagey, L., Schuetz, J.D., Boyer, J.L., 2006. Mrp4/ mice have an impaired cytoprotective response in obstructive cholestasis. Hepatology 43, 1013–1021. A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 73

Mennone, A., Soroka, C.J., Harry, K.M., Boyer, J.L., 2010. Role of breast cancer resistance protein in the adaptive response to cholestasis. Drug Metab. Dispos. 38, 1673–1678. Meyers, R.L., Book, L.S., O’Gorman, M.A., Jackson, W.D., Black, R.E., Johnson, D.G., Matlak, M.E., 2003. High-dose steroids, ursodeoxycholic acid, and chronic intravenous antibiotics improve bile flow after Kasai procedure in infants with biliary atresia. J. Pediatr. Surg. 38, 406–411. Milkiewicz, P., Roma, M.G., Elias, E., Coleman, R., 2002. Hepatoprotection with tauroursodeoxycholate and beta muricholate against taurolithocholate induced cholestasis: involvement of signal transduction pathways. Gut 51, 113–119. Miners, J.O., Birkett, D.J., 1998. Cytochrome P4502C9: an enzyme of major importance in human drug metabolism. Br. J. Clin. Pharmacol. 45, 525–538. Misawa, T., Hayashi, H., Makishima, M., Sugiyama, Y., Hashimoto, Y., 2012a. E297G mutated bile salt export pump (BSEP) function enhancers derived from GW4064: structural development study and separation from farnesoid X receptor-agonistic activity. Bioorg. Med. Chem. Lett. 22, 3962–3966. Misawa, T., Hayashi, H., Sugiyama, Y., Hashimoto, Y., 2012b. Discovery and structural development of small molecules that enhance transport activity of bile salt export pump mutant associated with progressive familial intrahepatic cholestasis type 2. Bioorg. Med. Chem. 20, 2940–2949. Miura, T., Ouchida, R., Yoshikawa, N., Okamoto, K., Makino, Y., Nakamura, T., Morimoto, C., Makino, I., Tanaka, H., 2001. Functional modulation of the glucocorticoid receptor and suppression of NF-kappaB-dependent transcription by ursodeoxycholic acid. J. Biol. Chem. 276, 47371–47378. Modica, S., Petruzzelli, M., Bellafante, E., Murzilli, S., Salvatore, L., Celli, N., Di Tullio, G., Palasciano, G., Moustafa, T., Halilbasic, E., et al, 2012. Selective activation of nuclear bile acid receptor FXR in the intestine protects mice against cholestasis. Gastroenterology. Morgan, R.E., Trauner, M., van Staden, C.J., Lee, P.H., Ramachandran, B., Eschenberg, M., Afshari, C.A., Qualls Jr., C.W., Lightfoot-Dunn, R., Hamadeh, H.K., 2010. Interference with bile salt export pump function is a susceptibility factor for human liver injury in drug development. Toxicol. Sci. 118, 485–500. Morita, R., Shimamoto, K., Ishii, Y., Kuwata, K., Ogawa, B., Imaoka, M., Hayashi, S.M., Suzuki, K., Shibutani, M., Mitsumori, K., 2011. Suppressive effect of enzymatically modified isoquercitrin on phenobarbital-induced liver tumor promotion in rats. Arch. Toxicol. 85, 1475–1484. Moschetta, A., Bookout, A.L., Mangelsdorf, D.J., 2004. Prevention of cholesterol gallstone disease by FXR agonists in a mouse model. Nat. Med. 10, 1352– 1358. Moseley, R.H., 1999. Sepsis and cholestasis. Clin. Liver Dis. 3, 465–475. Moseley, R.H., Wang, W., Takeda, H., Lown, K., Shick, L., Ananthanarayanan, M., Suchy, F.J., 1996. Effect of endotoxin on bile acid transport in rat liver: a potential model for sepsis-associated cholestasis. Am. J. Physiol. 271, G137–G146. Nakai, S., Masaki, T., Kurokohchi, K., Deguchi, A., Nishioka, M., 2000. Combination therapy of bezafibrate and ursodeoxycholic acid in primary biliary cirrhosis: a preliminary study. Am. J. Gastroenterol. 95, 326–327. Nathanson, M.H., Boyer, J.L., 1991. Mechanisms and regulation of bile secretion. Hepatology 14, 551–566. Nebert, D.W., Jones, J.E., 1989. Regulation of the mammalian cytochrome P1–450 (CYP1A1) gene. Int. J. Biochem. 21, 243–252. Nishida, T., Gatmaitan, Z., Che, M., Arias, I.M., 1991. Rat liver canalicular membrane vesicles contain an ATP-dependent bile acid transport system. Proc. Natl. Acad. Sci. USA 88, 6590–6594. Nishigaki, Y., Ohnishi, H., Moriwaki, H., Muto, Y., 1996. Ursodeoxycholic acid corrects defective natural killer activity by inhibiting prostaglandin E2 production in primary biliary cirrhosis. Dig. Dis. Sci. 41, 1487–1493. Nishimura, M., Yamaguchi, M., Yamauchi, A., Ueda, N., Naito, S., 2005. Role of soybean oil fat emulsion in the prevention of hepatic xenobiotic transporter mRNA up- and down-regulation induced by overdose of fat-free total parenteral nutrition in infant rats. Drug Metab. Pharmacokinet. 20, 46–54. Noe, J., Stieger, B., Meier, P.J., 2002. Functional expression of the canalicular bile salt export pump of human liver. Gastroenterology 123, 1659–1666. Odom, D.T., Zizlsperger, N., Gordon, D.B., Bell, G.W., Rinaldi, N.J., Murray, H.L., Volkert, T.L., Schreiber, J., Rolfe, P.A., Gifford, D.K., et al, 2004. Control of pancreas and liver gene expression by HNF transcription factors. Science 303, 1378–1381. Ogimura, E., Sekine, S., Horie, T., 2011. Bile salt export pump inhibitors are associated with bile acid-dependent drug-induced toxicity in sandwich-cultured hepatocytes. Biochem. Biophys. Res. Commun. 416, 313–317. Ogura, M., Nishida, S., Ishizawa, M., Sakurai, K., Shimizu, M., Matsuo, S., Amano, S., Uno, S., Makishima, M., 2009. Vitamin D3 modulates the expression of bile acid regulatory genes and represses inflammation in bile duct-ligated mice. J. Pharmacol. Exp. Ther. 328, 564–570. Okuwaki, M., Takada, T., Iwayanagi, Y., Koh, S., Kariya, Y., Fujii, H., Suzuki, H., 2007. LXR alpha transactivates mouse organic solute transporter alpha and beta via IR-1 elements shared with FXR. Pharm. Res. 24, 390–398. Ortlund, E.A., Lee, Y., Solomon, I.H., Hager, J.M., Safi, R., Choi, Y., Guan, Z., Tripathy, A., Raetz, C.R., McDonnell, D.P., et al, 2005. Modulation of human nuclear receptor LRH-1 activity by phospholipids and SHP. Nat. Struct. Mol. Biol. 12, 357–363. Palma, J., Reyes, H., Ribalta, J., Hernandez, I., Sandoval, L., Almuna, R., Liepins, J., Lira, F., Sedano, M., Silva, O., et al, 1997. Ursodeoxycholic acid in the treatment of cholestasis of pregnancy: a randomized, double-blind study controlled with placebo. J. Hepatol. 27, 1022–1028. Palmeira, C.M., Rolo, A.P., 2004. Mitochondrially-mediated toxicity of bile acids. Toxicology 203, 1–15. Pan, W., Song, I.S., Shin, H.J., Kim, M.H., Choi, Y.L., Lim, S.J., Kim, W.Y., Lee, S.S., Shin, J.G., 2011. Genetic polymorphisms in Na+-taurocholate co-transporting polypeptide (NTCP) and ileal apical sodium-dependent bile acid transporter (ASBT) and ethnic comparisons of functional variants of NTCP among Asian populations. Xenobiotica 41, 501–510. Parks, D.J., Blanchard, S.G., Bledsoe, R.K., Chandra, G., Consler, T.G., Kliewer, S.A., Stimmel, J.B., Willson, T.M., Zavacki, A.M., Moore, D.D., Lehmann, J.M., 1999. Bile acids: natural ligands for an orphan nuclear receptor. Science 284, 1365–1368. Pascussi, J.M., Drocourt, L., Fabre, J.M., Maurel, P., Vilarem, M.J., 2000a. Dexamethasone induces pregnane X receptor and retinoid X receptor-alpha expression in human hepatocytes: synergistic increase of CYP3A4 induction by pregnane X receptor activators. Mol. Pharmacol. 58, 361–372. Pascussi, J.M., Gerbal-Chaloin, S., Fabre, J.M., Maurel, P., Vilarem, M.J., 2000b. Dexamethasone enhances constitutive androstane receptor expression in human hepatocytes: consequences on cytochrome P450 gene regulation. Mol. Pharmacol. 58, 1441–1450. Pascussi, J.M., Gerbal-Chaloin, S., Pichard-Garcia, L., Daujat, M., Fabre, J.M., Maurel, P., Vilarem, M.J., 2000c. Interleukin-6 negatively regulates the expression of pregnane X receptor and constitutively activated receptor in primary human hepatocytes. Biochem. Biophys. Res. Commun. 274, 707–713. Patel, D.D., Knight, B.L., Soutar, A.K., Gibbons, G.F., Wade, D.P., 2000. The effect of peroxisome-proliferator-activated receptor-alpha on the activity of the cholesterol 7 alpha-hydroxylase gene. Biochem. J. 351 (Pt. 3), 747–753. Patterson, A.D., Shah, Y.M., Matsubara, T., Krausz, K.W., Gonzalez, F.J., 2012. Peroxisome proliferator-activated receptor alpha induction of uncoupling protein 2 protects against acetaminophen-induced liver toxicity. Hepatology 56, 281–290. Pauli-Magnus, C., Lang, T., Meier, Y., Zodan-Marin, T., Jung, D., Breymann, C., Zimmermann, R., Kenngott, S., Beuers, U., Reichel, C., et al, 2004. Sequence analysis of bile salt export pump (ABCB11) and multidrug resistance p-glycoprotein 3 (ABCB4, MDR3) in patients with intrahepatic cholestasis of pregnancy. Pharmacogenetics 14, 91–102. Paumgartner, G., Beuers, U., 2004. Mechanisms of action and therapeutic efficacy of ursodeoxycholic acid in cholestatic liver disease. Clin. Liver Dis. 8, 67– 81, vi. Pawlikowska, L., Strautnieks, S., Jankowska, I., Czubkowski, P., Emerick, K., Antoniou, A., Wanty, C., Fischler, B., Jacquemin, E., Wali, S., et al, 2010. Differences in presentation and progression between severe FIC1 and BSEP deficiencies. J. Hepatol. 53, 170–178. Pellicciari, R., Fiorucci, S., Camaioni, E., Clerici, C., Costantino, G., Maloney, P.R., Morelli, A., Parks, D.J., Willson, T.M., 2002. 6Alpha-ethyl-chenodeoxycholic acid (6-ECDCA), a potent and selective FXR agonist endowed with anticholestatic activity. J. Med. Chem. 45, 3569–3572. Plass, J.R., Mol, O., Heegsma, J., Geuken, M., Faber, K.N., Jansen, P.L., Muller, M., 2002. Farnesoid X receptor and bile salts are involved in transcriptional regulation of the gene encoding the human bile salt export pump. Hepatology 35, 589–596. Post, S.M., Duez, H., Gervois, P.P., Staels, B., Kuipers, F., Princen, H.M., 2001. Fibrates suppress bile acid synthesis via peroxisome proliferator-activated receptor-alpha-mediated downregulation of cholesterol 7alpha-hydroxylase and sterol 27-hydroxylase expression. Arterioscler. Thromb. Vasc. Biol. 21, 1840–1845. Poupon, R.E., 2000. Ursodeoxycholic acid for primary biliary cirrhosis: lessons from the past-issues for the future. J. Hepatol. 32, 685–688. Poupon, R., 2011. Treatment of primary biliary cirrhosis with ursodeoxycholic acid, budesonide and fibrates. Dig. Dis. 29, 85–88. 74 A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76

Poupon, R., 2012. Ursodeoxycholic acid and bile-acid mimetics as therapeutic agents for cholestatic liver diseases: an overview of their mechanismsof action. Clin. Res. Hepatol. Gastroenterol. 36 (Suppl. 1), S3–S12. Poupon, R., Poupon, R.E., 2000. Treatment of primary biliary cirrhosis. Baillieres Best Pract. Res. Clin. Gastroenterol. 14, 615–628. Prieto, J., Qian, C., Garcia, N., Diez, J., Medina, J.F., 1993. Abnormal expression of anion exchanger genes in primary biliary cirrhosis. Gastroenterology 105, 572–578. Prieto, J., Garcia, N., Marti-Climent, J.M., Penuelas, I., Richter, J.A., Medina, J.F., 1999. Assessment of biliary bicarbonate secretion in humans by positron emission tomography. Gastroenterology 117, 167–172. Prince, M.I., Burt, A.D., Jones, D.E., 2002. Hepatitis and liver dysfunction with rifampicin therapy for pruritus in primary biliary cirrhosis. Gut 50, 436–439. Rao, A., Haywood, J., Craddock, A.L., Belinsky, M.G., Kruh, G.D., Dawson, P.A., 2008. The organic solute transporter alpha–beta, Ostalpha–Ostbeta, is essential for intestinal bile acid transport and homeostasis. Proc. Natl. Acad. Sci. USA 105, 3891–3896. Rausa, F.M., Tan, Y., Zhou, H., Yoo, K.W., Stolz, D.B., Watkins, S.C., Franks, R.R., Unterman, T.G., Costa, R.H., 2000. Elevated levels of hepatocyte nuclear factor 3beta in mouse hepatocytes influence expression of genes involved in bile acid and glucose homeostasis. Mol. Cell. Biol. 20, 8264–8282. Rautiainen, H., Karkkainen, P., Karvonen, A.L., Nurmi, H., Pikkarainen, P., Nuutinen, H., Farkkila, M., 2005. Budesonide combined with UDCA to improve liver histology in primary biliary cirrhosis: a three-year randomized trial. Hepatology 41, 747–752. Reinehr, R., Graf, D., Haussinger, D., 2003. Bile salt-induced hepatocyte apoptosis involves epidermal growth factor receptor-dependent CD95 tyrosine phosphorylation. Gastroenterology 125, 839–853. Renner, O., Harsch, S., Strohmeyer, A., Schimmel, S., Stange, E.F., 2008. Reduced ileal expression of OSTalpha–OSTbeta in non-obese gallstone disease. J. Lipid Res. 49, 2045–2054. Rizzo, G., Passeri, D., De Franco, F., Ciaccioli, G., Donadio, L., Rizzo, G., Orlandi, S., Sadeghpour, B., Wang, X.X., Jiang, T., et al, 2010. Functional characterization of the semisynthetic bile acid derivative INT-767, a dual farnesoid X receptor and TGR5 agonist. Mol. Pharmacol. 78, 617–630. Roglans, N., Vazquez-Carrera, M., Alegret, M., Novell, F., Zambon, D., Ros, E., Laguna, J.C., Sanchez, R.M., 2004. Fibrates modify the expression of key factors involved in bile-acid synthesis and biliary-lipid secretion in gallstone patients. Eur. J. Clin. Pharmacol. 59, 855–861. Rosales, R., Romero, M.R., Vaquero, J., Monte, M.J., Requena, P., Martinez-Augustin, O., Sanchez de Medina, F., Marin, J.J., 2013. FXR-dependent and- independent interaction of glucocorticoids with the regulatory pathways involved in the control of bile acid handling by the liver. Biochem. Pharmacol. 85, 829–838. Saini, S.P., Sonoda, J., Xu, L., Toma, D., Uppal, H., Mu, Y., Ren, S., Moore, D.D., Evans, R.M., Xie, W., 2004. A novel constitutive androstane receptor-mediated and CYP3A-independent pathway of bile acid detoxification. Mol. Pharmacol. 65, 292–300. Sato, H., Macchiarulo, A., Thomas, C., Gioiello, A., Une, M., Hofmann, A.F., Saladin, R., Schoonjans, K., Pellicciari, R., Auwerx, J., 2008. Novel potent and selective bile acid derivatives as TGR5 agonists: biological screening, structure–activity relationships, and molecular modeling studies. J. Med. Chem. 51, 1831–1841. Savkur, R.S., Thomas, J.S., Bramlett, K.S., Gao, Y., Michael, L.F., Burris, T.P., 2005. Ligand-dependent coactivation of the human bile acid receptor FXR by the peroxisome proliferator-activated receptor gamma coactivator-1alpha. J. Pharmacol. Exp. Ther. 312, 170–178. Sayin, S.I., Wahlstrom, A., Felin, J., Jantti, S., Marschall, H.U., Bamberg, K., Angelin, B., Hyotylainen, T., Oresic, M., Backhed, F., 2013. Gut microbiota regulates bile acid metabolism by reducing the levels of tauro-beta-muricholic acid, a naturally occurring FXR antagonist. Cell Metab. 17, 225–235. Scheimann, A.O., Strautnieks, S.S., Knisely, A.S., Byrne, J.A., Thompson, R.J., Finegold, M.J., 2007. Mutations in bile salt export pump (ABCB11) in two children with progressive familial intrahepatic cholestasis and cholangiocarcinoma. J. Pediatr. 150, 556–559. Setchell, K.D., Rodrigues, C.M., Clerici, C., Solinas, A., Morelli, A., Gartung, C., Boyer, J., 1997. Bile acid concentrations in human and rat liver tissue and in hepatocyte nuclei. Gastroenterology 112, 226–235. Seward, D.J., Koh, A.S., Boyer, J.L., Ballatori, N., 2003. Functional complementation between a novel mammalian polygenic transport complex and an evolutionarily ancient organic solute transporter, OSTalpha–OSTbeta. J. Biol. Chem. 278, 27473–27482. She, H., Xiong, S., Hazra, S., Tsukamoto, H., 2005. Adipogenic transcriptional regulation of hepatic stellate cells. J. Biol. Chem. 280, 4959–4967. Sheridan, R.M., Gupta, A., Miethke, A., Knisely, A.S., Bove, K.E., 2012. Multiple dysplastic liver nodules in PFIC2 underscore risk for neoplasia associated with functional BSEP deficiency. Am. J. Surg. Pathol. 36, 785–786. Shiao, T., Iwahashi, M., Fortune, J., Quattrochi, L., Bowman, S., Wick, M., Qadri, I., Simon, F.R., 2000. Structural and functional characterization of liver cell- specific activity of the human sodium/taurocholate cotransporter. Genomics 69, 203–213. Shih, D.Q., Bussen, M., Sehayek, E., Ananthanarayanan, M., Shneider, B.L., Suchy, F.J., Shefer, S., Bollileni, J.S., Gonzalez, F.J., Breslow, J.L., Stoffel, M., 2001. Hepatocyte nuclear factor-1alpha is an essential regulator of bile acid and plasma cholesterol metabolism. Nat. Genet. 27, 375–382. Shneider, B.L., Fox, V.L., Schwarz, K.B., Watson, C.L., Ananthanarayanan, M., Thevananther, S., Christie, D.M., Hardikar, W., Setchell, K.D., Mieli-Vergani, G., et al, 1997. Hepatic basolateral sodium-dependent-bile acid transporter expression in two unusual cases of hypercholanemia and in extrahepatic biliary atresia. Hepatology 25, 1176–1183. Shoda, J., Inada, Y., Tsuji, A., Kusama, H., Ueda, T., Ikegami, T., Suzuki, H., Sugiyama, Y., Cohen, D.E., Tanaka, N., 2004. Bezafibrate stimulates canalicular localization of NBD-labeled PC in HepG2 cells by PPARalpha-mediated redistribution of ABCB4. J. Lipid Res. 45, 1813–1825. Simon, F.R., Fortune, J., Iwahashi, M., Gartung, C., Wolkoff, A., Sutherland, E., 1996. Ethinyl estradiol cholestasis involves alterations in expression of liver sinusoidal transporters. Am. J. Physiol. 271, G1043–G1052. Simon, F.R., Fortune, J., Iwahashi, M., Qadri, I., Sutherland, E., 2004. Multihormonal regulation of hepatic sinusoidal Ntcp gene expression. Am. J. Physiol. Gastrointest. Liver Physiol. 287, G782–G794. Smit, J.J., Schinkel, A.H., Oude Elferink, R.P., Groen, A.K., Wagenaar, E., van Deemter, L., Mol, C.A., Ottenhoff, R., van der Lugt, N.M., van Roon, M.A., 1993. Homozygous disruption of the murine mdr2 P-glycoprotein gene leads to a complete absence of phospholipid from bile and to liver disease. Cell 75, 451–462. Snow, K.L., Moseley, R.H., 2007. Effect of thiazolidinediones on bile acid transport in rat liver. Life Sci. 80, 732–740. Sokol, R.J., Devereaux, M., Dahl, R., Gumpricht, E., 2006. ‘‘Let there be bile’’-understanding hepatic injury in cholestasis. J. Pediatr. Gastroenterol. Nutr. 43 (Suppl. 1), S4–S9. Song, C.S., Echchgadda, I., Baek, B.S., Ahn, S.C., Oh, T., Roy, A.K., Chatterjee, B., 2001. Dehydroepiandrosterone sulfotransferase gene induction by bile acid activated farnesoid X receptor. J. Biol. Chem. 276, 42549–42556. Song, X., Kaimal, R., Yan, B., Deng, R., 2008. Liver receptor homolog 1 transcriptionally regulates human bile salt export pump expression. J. Lipid Res. 49, 973–984. Soroka, C.J., Mennone, A., Hagey, L.R., Ballatori, N., Boyer, J.L., 2010. Mouse organic solute transporter alpha deficiency enhances renal excretion of bile acids and attenuates cholestasis. Hepatology 51, 181–190. Soroka, C.J., Velazquez, H., Mennone, A., Ballatori, N., Boyer, J.L., 2011. Ostalpha depletion protects liver from oral bile acid load. Am. J. Physiol. Gastrointest. Liver Physiol. 301, G574–G579. Souza, R.F., Krishnan, K., Spechler, S.J., 2008. Acid, bile, and CDX: the ABCs of making Barrett’s metaplasia. Am. J. Physiol. Gastrointest. Liver Physiol. 295, G211–G218. Staudinger, J., Liu, Y., Madan, A., Habeebu, S., Klaassen, C.D., 2001a. Coordinate regulation of xenobiotic and bile acid homeostasis by pregnane X receptor. Drug Metab. Dispos. 29, 1467–1472. Staudinger, J.L., Goodwin, B., Jones, S.A., Hawkins-Brown, D., MacKenzie, K.I., LaTour, A., Liu, Y., Klaassen, C.D., Brown, K.K., Reinhard, J., et al, 2001b. The nuclear receptor PXR is a lithocholic acid sensor that protects against liver toxicity. Proc. Natl. Acad. Sci. USA 98, 3369–3374. Stedman, C., Liddle, C., Coulter, S., Sonoda, J., Alvarez, J.G., Evans, R.M., Downes, M., 2006. Benefit of farnesoid X receptor inhibition in obstructive cholestasis. Proc. Natl. Acad. Sci. USA 103, 11323–11328. Stieger, B., 2010. Role of the bile salt export pump, BSEP, in acquired forms of cholestasis. Drug Metab. Rev. 42, 437–445. A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76 75

Stieger, B., Beuers, U., 2011. The canalicular bile salt export pump BSEP (ABCB11) as a potential therapeutic target. Curr. Drug Targets 12, 661–670. Stieger, B., Hagenbuch, B., Landmann, L., Hochli, M., Schroeder, A., Meier, P.J., 1994. In situ localization of the hepatocytic Na+/taurocholate cotransporting polypeptide in rat liver. Gastroenterology 107, 1781–1787. Stieger, B., Fattinger, K., Madon, J., Kullak-Ublick, G.A., Meier, P.J., 2000. Drug- and estrogen-induced cholestasis through inhibition of the hepatocellular bile salt export pump (Bsep) of rat liver. Gastroenterology 118, 422–430. Stiehl, A., Thaler, M.M., Admirand, W.H., 1972. The effects of phenobarbital on bile salts and bilirubin in patients with intrahepatic and extrahepatic cholestasis. N. Engl. J. Med. 286, 858–861. Strautnieks, S.S., Bull, L.N., Knisely, A.S., Kocoshis, S.A., Dahl, N., Arnell, H., Sokal, E., Dahan, K., Childs, S., Ling, V., et al, 1998. A gene encoding a liver-specific ABC transporter is mutated in progressive familial intrahepatic cholestasis. Nat. Genet. 20, 233–238. Strautnieks, S.S., Byrne, J.A., Pawlikowska, L., Cebecauerova, D., Rayner, A., Dutton, L., Meier, Y., Antoniou, A., Stieger, B., Arnell, H., et al, 2008. Severe bile salt export pump deficiency: 82 different ABCB11 mutations in 109 families. Gastroenterology 134, 1203–1214. Su, H., Ma, C., Liu, J., Li, N., Gao, M., Huang, A., Wang, X., Huang, W., Huang, X., 2012. Downregulation of nuclear receptor FXR is associated with multiple malignant clinicopathological characteristics in human hepatocellular carcinoma. Am. J. Physiol. Gastrointest. Liver Physiol. 303, G1245–G1253. Sueyoshi, T., Kawamoto, T., Zelko, I., Honkakoski, P., Negishi, M., 1999. The repressed nuclear receptor CAR responds to phenobarbital in activating the human CYP2B6 gene. J. Biol. Chem. 274, 6043–6046. Sugatani, J., Nishitani, S., Yamakawa, K., Yoshinari, K., Sueyoshi, T., Negishi, M., Miwa, M., 2005. Transcriptional regulation of human UGT1A1 gene expression: activated glucocorticoid receptor enhances constitutive androstane receptor/pregnane X receptor-mediated UDP-glucuronosyltransferase 1A1 regulation with glucocorticoid receptor-interacting protein 1. Mol. Pharmacol. 67, 845–855. Sun, A.Q., Balasubramaniyan, N., Xu, K., Liu, C.J., Ponamgi, V.M., Liu, H., Suchy, F.J., 2007. Protein-protein interactions and membrane localization of the human organic solute transporter. Am. J. Physiol. Gastrointest. Liver Physiol. 292, G1586–G1593. Tanaka, H., Makino, I., 1992. Ursodeoxycholic acid-dependent activation of the glucocorticoid receptor. Biochem. Biophys. Res. Commun. 188, 942–948. Tanaka, H., Makino, Y., Miura, T., Hirano, F., Okamoto, K., Komura, K., Sato, Y., Makino, I., 1996. Ligand-independent activation of the glucocorticoid receptor by ursodeoxycholic acid. Repression of IFN-gamma-induced MHC class II gene expression via a glucocorticoid receptor-dependent pathway. J. Immunol. 156, 1601–1608. Tanaka, A., Nezu, S., Uegaki, S., Kikuchi, K., Shibuya, A., Miyakawa, H., Takahashi, S., Bianchi, I., Zermiani, P., Podda, M., et al, 2009. Vitamin D receptor polymorphisms are associated with increased susceptibility to primary biliary cirrhosis in Japanese and Italian populations. J. Hepatol. 50, 1202–1209. Teng, S., Piquette-Miller, M., 2005. The involvement of the pregnane X receptor in hepatic gene regulation during inflammation in mice. J. Pharmacol. Exp. Ther. 312, 841–848. Teng, S., Piquette-Miller, M., 2007. Hepatoprotective role of PXR activation and MRP3 in cholic acid-induced cholestasis. Br. J. Pharmacol. 151, 367–376. Thomas, C., Pellicciari, R., Pruzanski, M., Auwerx, J., Schoonjans, K., 2008. Targeting bile-acid signalling for metabolic diseases. Nat. Rev. Drug Discov. 7, 678– 693. Thomas, C., Gioiello, A., Noriega, L., Strehle, A., Oury, J., Rizzo, G., Macchiarulo, A., Yamamoto, H., Mataki, C., Pruzanski, M., et al, 2009. TGR5-mediated bile acid sensing controls glucose homeostasis. Cell Metab. 10, 167–177. Trauner, M., Boyer, J.L., 2003. Bile salt transporters: molecular characterization, function, and regulation. Physiol. Rev. 83, 633–671. Trauner, M., Arrese, M., Lee, H., Boyer, J.L., Karpen, S.J., 1998. Endotoxin downregulates rat hepatic ntcp gene expression via decreased activity of critical transcription factors. J. Clin. Invest. 101, 2092–2100. Trauner, M., Baghdasaryan, A., Claudel, T., Fickert, P., Halilbasic, E., Moustafa, T., Zollner, G., 2011. Targeting nuclear bile acid receptors for liver disease. Dig. Dis. 29, 98–102. Turncliff, R.Z., Tian, X., Brouwer, K.L., 2006. Effect of culture conditions on the expression and function of Bsep, Mrp2, and Mdr1a/b in sandwich-cultured rat hepatocytes. Biochem. Pharmacol. 71, 1520–1529. van Mil, S.W., van der Woerd, W.L., van der Brugge, G., Sturm, E., Jansen, P.L., Bull, L.N., van den Berg, I.E., Berger, R., Houwen, R.H., Klomp, L.W., 2004. Benign recurrent intrahepatic cholestasis type 2 is caused by mutations in ABCB11. Gastroenterology 127, 379–384. Vogel, A., Strassburg, C.P., Manns, M.P., 2002. Genetic association of vitamin D receptor polymorphisms with primary biliary cirrhosis and autoimmune hepatitis. Hepatology 35, 126–131. Wagner, M., Fickert, P., Zollner, G., Fuchsbichler, A., Silbert, D., Tsybrovskyy, O., Zatloukal, K., Guo, G.L., Schuetz, J.D., Gonzalez, F.J., et al, 2003. Role of farnesoid X receptor in determining hepatic ABC transporter expression and liver injury in bile duct-ligated mice. Gastroenterology 125, 825–838. Wagner, M., Halilbasic, E., Marschall, H.U., Zollner, G., Fickert, P., Langner, C., Zatloukal, K., Denk, H., Trauner, M., 2005. CAR and PXR agonists stimulate hepatic bile acid and bilirubin detoxification and elimination pathways in mice. Hepatology 42, 420–430. Wagner, M., Zollner, G., Trauner, M., 2011. Nuclear receptors in liver disease. Hepatology 53, 1023–1034. Walkowiak, J., Jankowska, I., Pawlowska, J., Strautnieks, S., Bull, L., Thompson, R., Herzig, K.H., Socha, J., 2006. Exocrine pancreatic function in children with progressive familial intrahepatic cholestasis type 2. J. Pediatr. Gastroenterol. Nutr. 42, 416–418. Wang, H., Chen, J., Hollister, K., Sowers, L.C., Forman, B.M., 1999. Endogenous bile acids are ligands for the nuclear receptor FXR/BAR. Mol. Cell 3, 543–553. Wang, R., Salem, M., Yousef, I.M., Tuchweber, B., Lam, P., Childs, S.J., Helgason, C.D., Ackerley, C., Phillips, M.J., Ling, V., 2001a. Targeted inactivation of sister of P-glycoprotein gene (spgp) in mice results in nonprogressive but persistent intrahepatic cholestasis. Proc. Natl. Acad. Sci. USA 98, 2011–2016. Wang, W., Seward, D.J., Li, L., Boyer, J.L., Ballatori, N., 2001b. Expression cloning of two genes that together mediate organic solute and steroid transport in the liver of a marine vertebrate. Proc. Natl. Acad. Sci. USA 98, 9431–9436. Wang, D.Q., Tazuma, S., Cohen, D.E., Carey, M.C., 2003a. Feeding natural hydrophilic bile acids inhibits intestinal cholesterol absorption: studies in the gallstone-susceptible mouse. Am. J. Physiol. Gastrointest. Liver Physiol. 285, G494–G502. Wang, L., Han, Y., Kim, C.S., Lee, Y.K., Moore, D.D., 2003b. Resistance of SHP-null mice to bile acid-induced liver damage. J. Biol. Chem. 278, 44475–44481. Wang, Y.D., Chen, W.D., Wang, M., Yu, D., Forman, B.M., Huang, W., 2008. Farnesoid X receptor antagonizes nuclear factor kappaB in hepatic inflammatory response. Hepatology 48, 1632–1643. Wang, H.H., Lammert, F., Schmitz, A., Wang, D.Q., 2010. Transgenic overexpression of Abcb11 enhances biliary bile salt outputs, but does not affect cholesterol cholelithogenesis in mice. Eur. J. Clin. Invest. 40, 541–551. Warskulat, U., Kubitz, R., Wettstein, M., Stieger, B., Meier, P.J., Haussinger, D., 1999. Regulation of bile salt export pump mRNA levels by dexamethasone and osmolarity in cultured rat hepatocytes. Biol. Chem. 380, 1273–1279. Watanabe, M., Houten, S.M., Mataki, C., Christoffolete, M.A., Kim, B.W., Sato, H., Messaddeq, N., Harney, J.W., Ezaki, O., Kodama, T., et al, 2006. Bile acids induce energy expenditure by promoting intracellular thyroid hormone activation. Nature 439, 484–489. Weerachayaphorn, J., Cai, S.Y., Soroka, C.J., Boyer, J.L., 2009. Nuclear factor erythroid 2-related factor 2 is a positive regulator of human bile salt export pump expression. Hepatology 50, 1588–1596. Wolters, H., Elzinga, B.M., Baller, J.F., Boverhof, R., Schwarz, M., Stieger, B., Verkade, H.J., Kuipers, F., 2002. Effects of bile salt flux variations on the expression of hepatic bile salt transporters in vivo in mice. J. Hepatol. 37, 556–563. Xie, W., Barwick, J.L., Downes, M., Blumberg, B., Simon, C.M., Nelson, M.C., Neuschwander-Tetri, B.A., Brunt, E.M., Guzelian, P.S., Evans, R.M., 2000. Humanized xenobiotic response in mice expressing nuclear receptor SXR. Nature 406, 435–439. Xie, W., Radominska-Pandya, A., Shi, Y., Simon, C.M., Nelson, M.C., Ong, E.S., Waxman, D.J., Evans, R.M., 2001. An essential role for nuclear receptors SXR/PXR in detoxification of cholestatic bile acids. Proc. Natl. Acad. Sci. USA 98, 3375–3380. Yamamoto, Y., Moore, R., Goldsworthy, T.L., Negishi, M., Maronpot, R.R., 2004. The orphan nuclear receptor constitutive active/androstane receptor is essential for liver tumor promotion by phenobarbital in mice. Cancer Res. 64, 7197–7200. Yamamoto, Y., Moore, R., Hess, H.A., Guo, G.L., Gonzalez, F.J., Korach, K.S., Maronpot, R.R., Negishi, M., 2006. Estrogen receptor alpha mediates 17alpha- ethynylestradiol causing hepatotoxicity. J. Biol. Chem. 281, 16625–16631. 76 A. Baghdasaryan et al. / Molecular Aspects of Medicine 37 (2014) 57–76

Yamanishi, Y., Nosaka, Y., Kawasaki, H., Hirayama, C., Ikawa, S., 1985. Sterol and bile acid metabolism after short-term prednisolone treatment in patients with chronic active hepatitis. Gastroenterol. Jpn. 20, 246–251. Yamazaki, K., Suzuki, K., Nakamura, A., Sato, S., Lindor, K.D., Batts, K.P., Tarara, J.E., Kephart, G.M., Kita, H., Gleich, G.J., 1999. Ursodeoxycholic acid inhibits eosinophil degranulation in patients with primary biliary cirrhosis. Hepatology 30, 71–78. Yamazaki, Y., Moore, R., Negishi, M., 2011. Nuclear receptor CAR (NR1I3) is essential for DDC-induced liver injury and oval cell proliferation in mouse liver. Lab. Invest. 91, 1624–1633. Yano, K., Kato, H., Morita, S., Takahara, O., Ishibashi, H., Furukawa, R., 2002. Is bezafibrate histologically effective for primary biliary cirrhosis? Am. J. Gastroenterol. 97, 1075–1077. Yerushalmi, B., Sokol, R.J., Narkewicz, M.R., Smith, D., Karrer, F.M., 1999. Use of rifampin for severe pruritus in children with chronic cholestasis. J. Pediatr. Gastroenterol. Nutr. 29, 442–447. Yoshikawa, M., Tsujii, T., Matsumura, K., Yamao, J., Matsumura, Y., Kubo, R., Fukui, H., Ishizaka, S., 1992. Immunomodulatory effects of ursodeoxycholic acid on immune responses. Hepatology 16, 358–364. Yu, J., Lo, J.L., Huang, L., Zhao, A., Metzger, E., Adams, A., Meinke, P.T., Wright, S.D., Cui, J., 2002. Lithocholic acid decreases expression of bile salt export pump through farnesoid X receptor antagonist activity. J. Biol. Chem. 277, 31441–31447. Zelcer, N., van de Wetering, K., de Waart, R., Scheffer, G.L., Marschall, H.U., Wielinga, P.R., Kuil, A., Kunne, C., Smith, A., van der Valk, M., et al, 2006. Mice lacking Mrp3 (Abcc3) have normal bile salt transport, but altered hepatic transport of endogenous glucuronides. J. Hepatol. 44, 768–775. Zhang, Y., Castellani, L.W., Sinal, C.J., Gonzalez, F.J., Edwards, P.A., 2004. Peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PGC-1alpha) regulates triglyceride metabolism by activation of the nuclear receptor FXR. Genes Dev. 18, 157–169. Zhang, F., Lu, Y., Zheng, S., 2012. Peroxisome proliferator-activated receptor-gamma cross-regulation of signaling events implicated in liver fibrogenesis. Cell. Signal. 24, 596–605. Zimmermann, C., van Waterschoot, R.A., Harmsen, S., Maier, A., Gutmann, H., Schinkel, A.H., 2009. PXR-mediated induction of human CYP3A4 and mouse Cyp3a11 by the glucocorticoid budesonide. Eur. J. Pharm. Sci. 36, 565–571. Zollner, G., Fickert, P., Zenz, R., Fuchsbichler, A., Stumptner, C., Kenner, L., Ferenci, P., Stauber, R.E., Krejs, G.J., Denk, H., et al, 2001. Hepatobiliary transporter expression in percutaneous liver biopsies of patients with cholestatic liver diseases. Hepatology 33, 633–646. Zollner, G., Fickert, P., Fuchsbichler, A., Silbert, D., Wagner, M., Arbeiter, S., Gonzalez, F.J., Marschall, H.U., Zatloukal, K., Denk, H., Trauner, M., 2003a. Role of nuclear bile acid receptor, FXR, in adaptive ABC transporter regulation by cholic and ursodeoxycholic acid in mouse liver, kidney and intestine. J. Hepatol. 39, 480–488. Zollner, G., Fickert, P., Silbert, D., Fuchsbichler, A., Marschall, H.U., Zatloukal, K., Denk, H., Trauner, M., 2003b. Adaptive changes in hepatobiliary transporter expression in primary biliary cirrhosis. J. Hepatol. 38, 717–727. Zollner, G., Wagner, M., Fickert, P., Geier, A., Fuchsbichler, A., Silbert, D., Gumhold, J., Zatloukal, K., Kaser, A., Tilg, H., et al, 2005. Role of nuclear receptors and hepatocyte-enriched transcription factors for Ntcp repression in biliary obstruction in mouse liver. Am. J. Physiol. Gastrointest. Liver Physiol. 289, G798–G805. Zollner, G., Marschall, H.U., Wagner, M., Trauner, M., 2006a. Role of nuclear receptors in the adaptive response to bile acids and cholestasis: pathogenetic and therapeutic considerations. Mol. Pharm. 3, 231–251. Zollner, G., Wagner, M., Moustafa, T., Fickert, P., Silbert, D., Gumhold, J., Fuchsbichler, A., Halilbasic, E., Denk, H., Marschall, H.U., Trauner, M., 2006b. Coordinated induction of bile acid detoxification and alternative elimination in mice: role of FXR-regulated organic solute transporter-alpha/beta in the adaptive response to bile acids. Am. J. Physiol. Gastrointest. Liver Physiol. 290, G923–G932.