ABSTRACT
Farnesoid X receptor (FXR) is a nuclear receptor that regulates the synthesis and enterohepatic circulation of bile acids (BAs). It also regulates lipid and carbohydrate metabolism, making FXR ligands potential therapeutic agents for systemic and/or hepatic metabolic disorders. We previously synthesized a series of FXR antagonists and showed that oral administration of FLG249 reduced the expression of several FXR target genes in the mouse ileum. Here, we investigated the effects of FLG249 on lipid metabolism in mice fed a high-fat diet (HFD). When FLG249 was administered for 4 weeks to HFD-induced obese mice, it altered the expression of genes related to BA metabolism, ceramide synthesis and fatty acid ß-oxidation, improving lipid metabolism in the liver and ileum without decreasing body weight. These findings suggest that FLG249 has the potential to be a low toxicity pharmaceutical compound and likely acts as a nonsteroidal FXR antagonist to improve lipid metabolism disorders.
Subject(s)
Cholesterol , Diet, High-Fat , Liver , Mice, Inbred C57BL , Obesity , Receptors, Cytoplasmic and Nuclear , Triglycerides , Animals , Diet, High-Fat/adverse effects , Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors , Receptors, Cytoplasmic and Nuclear/metabolism , Male , Liver/metabolism , Liver/drug effects , Obesity/drug therapy , Obesity/metabolism , Obesity/blood , Cholesterol/blood , Triglycerides/blood , Lipid Metabolism/drug effects , Bile Acids and Salts/metabolism , Mice , Mice, Obese , Ileum/metabolism , Ileum/drug effectsABSTRACT
We image local superfluid density in single crystals of Pd-intercalated ErTe_{3} below the superconducting critical temperature T_{c}, well below the onset temperature T_{CDW} of (disordered) charge-density-wave order. We find no detectable inhomogeneities on micron scales. We observe a rapid increase of the superfluid density below T_{c}, deviating from the behavior expected in a conventional Bardeen-Cooper-Schrieffer superconductor, and show that the temperature dependence is qualitatively consistent with a combination of quantum and thermal phase fluctuations.
ABSTRACT
The coexistence of superconductivity and ferromagnetism is an intrinsically interesting research focus in condensed matter physics, but the study is limited by low superconducting (Tc) and magnetic (Tm) transition temperatures in related materials. Here, we used a scanning superconducting quantum interference device to image the in situ diamagnetic and ferromagnetic responses of RbEuFe4As4 with high Tc and Tm. We observed significant suppression of the superfluid density in the vicinity of the magnetic phase transition, signifying fluctuation-enhanced magnetic scatterings between Eu spins and Fe 3d conduction electrons. Intriguingly, we observed multiple ferromagnetic domains that should be absent in an ideal magnetic helical phase. The formation of these domains demonstrates a weak c-axis ferromagnetic component probably arising from the Eu spin-canting effect, indicative of possible superconductivity-driven domain Meissner and domain vortex-antivortex phases, as revealed in EuFe2(As0.79P0.21)2. Our observations highlight that RbEuFe4As4 is a unique system that includes multiple interplay channels between superconductivity and ferromagnetism.
ABSTRACT
Shwachman-Diamond syndrome (SDS) is an autosomal recessive disorder characterized by exocrine pancreatic insufficiency and bone marrow failure. The depletion of SBDS protein by RNA interference has been shown to cause inhibition of cell proliferation in several cell lines. However, the precise mechanism by which the loss of SBDS leads to inhibition of cell growth remains unknown. To evaluate the impaired growth of SBDS-knockdown cells, we analyzed Epstein-Barr virus-transformed lymphoblast cells (LCLs) derived from two patients with SDS (c. 183_184TA > CT and c. 258 + 2 T > C). After 3 days of culture, the growth of LCL-SDS cell lines was considerably less than that of control donor cells. By annealing control primer-based GeneFishing PCR screening, we found that galectin-1 (Gal-1) mRNA expression was elevated in LCL-SDS cells. Western blot analysis showed that the level of Gal-1 protein expression was also increased in LCL-SDS cells as well as in SBDS-knockdown 32Dcl3 murine myeloid cells. We confirmed that recombinant Gal-1 inhibited the proliferation of both LCL-control and LCL-SDS cells and induced apoptosis (as determined by annexin V-positive staining). These results suggest that the overexpression of Gal-1 contributes to abnormal cell growth in SBDS-deficient cells.
Subject(s)
Benzamides , Bone Marrow Diseases , Epstein-Barr Virus Infections , Exocrine Pancreatic Insufficiency , Galectin 1 , Tyrosine , Animals , Humans , Mice , Bone Marrow Diseases/genetics , Cell Proliferation , Exocrine Pancreatic Insufficiency/genetics , Exocrine Pancreatic Insufficiency/metabolism , Galectin 1/genetics , Herpesvirus 4, Human , Proteins , Shwachman-Diamond Syndrome , Tyrosine/analogs & derivativesABSTRACT
Magnetic field penetrates type-II bulk superconductors by forming quantum vortices that enclose a magnetic flux equal to the magnetic flux quantum. The flux quantum is a universal quantity that depends only on fundamental constants. In this study, we investigated isolated vortices in the hole-overdoped Ba1-xKxFe2As2 (x = 0.77) by using scanning superconducting quantum interference device (SQUID) magnetometry. In many locations, we observed objects that carried only part of a flux quantum, with a magnitude that varied continuously with temperature. We demonstrated mobility and manipulability of these objects and interpreted them as quantum vortices with nonuniversally quantized (fractional) magnetic flux whose magnitude is determined by the temperature-dependent parameters of a multicomponent superconductor.
ABSTRACT
Odd-parity superconductor UTe_{2} shows spontaneous time-reversal symmetry breaking and multiple superconducting phases, which imply chiral superconductivity, but only in a subset of samples. Here we microscopically observe a homogeneous superfluid density n_{s} on the surface of UTe_{2} and an enhanced superconducting transition temperature near the edges. We also detect vortex-antivortex pairs even at zero magnetic field, indicating the existence of a hidden internal field. The temperature dependence of n_{s}, determined independent of sample geometry, does not support point nodes along the b axis for a quasi-2D Fermi surface and provides no evidence for multiple phase transitions in UTe_{2}.
ABSTRACT
Farnesoid X receptor (FXR) and peroxisome proliferator-activated receptor (PPAR)γ are nuclear receptor 1 superfamily of transcription factors. FXR and PPARγ agonists have been individually investigated in clinical trial of anti-diabetic agents in the patients with nonalcoholic fatty liver disease (NAFLD). Regarding recent agonist development, the partial agonists for FXR and PPARγ are drawing attention from the standpoint of avoiding overactive responses caused by full agonists. In this article, we report that 18 with a benzimidazole scaffold possesses FXR/PPARγ dual partial agonistic activity. In addition, 18 shares the ability to reduce cyclin-dependent kinase 5-mediated phosphorylation of PPARγ-Ser273 and the metabolic stability in mouse liver microsome assay. To date, there are no published reports on FXR/PPARγ dual partial agonists with biological profiles similar to 18. Thus, the analog would be a feasible candidate as an unprecedented approach to NAFLD associated with type 2 diabetes mellitus.
Subject(s)
Diabetes Mellitus, Type 2 , Non-alcoholic Fatty Liver Disease , Mice , Animals , PPAR gamma/agonists , Non-alcoholic Fatty Liver Disease/drug therapy , Diabetes Mellitus, Type 2/drug therapy , Transcription Factors , Hypoglycemic Agents/pharmacologyABSTRACT
Secondary bile acids (SBAs) with high hydrophobicity are abundant in the colonic lumen. However, both aggravating and protective roles of SBAs have been proposed in the pathogenesis of inflammatory bowel diseases (IBDs). We observed that oral administration of hyodeoxycholic acid (HDCA), a hydrophilic bile acid, prevented the development of dextran sulfate sodium (DSS)-induced colitis in mice. We then examined the individual effects of DSS and HDCA as well as their combined effects on fecal bile acid profile in mice. HDCA treatment increased the levels of most of fecal bile acids, whereas DSS treatment had limited effects on the levels of fecal bile acids. The combined treatment with DSS and HDCA synergistically increased the levels of fecal chenodeoxycholic acid (CDCA) and deoxycholic acid (DCA) in feces, which are potent activators of the farnesoid X receptor (FXR) and Takeda G-protein-coupled receptor 5 (TGR5). The overall hydrophobicity of fecal bile acids was not modified by any treatments. Our data suggest that the preventive effect of HDCA on DSS-induced colitis in mice is due to the synergism between DSS and HDCA in increasing the levels of the fecal bile acids with potencies to activate FXR and TGR5.
Subject(s)
Colitis , Animals , Bile Acids and Salts , Chenodeoxycholic Acid/adverse effects , Colitis/chemically induced , Colitis/drug therapy , Colitis/prevention & control , Deoxycholic Acid/adverse effects , Dextran Sulfate , Mice , Receptors, G-Protein-CoupledABSTRACT
Farnesoid X receptor (FXR) controls gene-expression relevant to various diseases including nonalcoholic steatohepatitis and has become a drug target to regulate metabolic aberrations. However, some side effects of FXR agonists reported in clinical development such as an increase in blood cholesterol levels incentivize the development of partial agonists to minimize side effects. In this study, to identify a new partial agonist, we analyzed the computational structure-activity relationship (SAR) of FXR agonists previously developed in our laboratories using molecular dynamics simulations. SAR analysis showed that fluctuations in the H8 helix, by ligand binding, of the ligand-binding domain (LBD) of FXR may influence agonistic activity. Based on this observation, 6 was newly designed as a partial agonist and synthesized. As a result of biological evaluations, 6 showed weak agonistic activity (40.0% relative agonistic activity to the full-agonist GW4064) and a potent EC50 value (55.5 nM). The successful identification of the new potent partial agonist 6 suggested that helix fluctuation in the LBD induced by ligands could be one way to develop partial agonists.
Subject(s)
Chenodeoxycholic Acid/pharmacology , Drug Design , Molecular Dynamics Simulation , Receptors, Cytoplasmic and Nuclear/agonists , Binding Sites/drug effects , Chenodeoxycholic Acid/chemistry , Dose-Response Relationship, Drug , Humans , Ligands , Molecular Structure , Receptors, Cytoplasmic and Nuclear/genetics , Receptors, Cytoplasmic and Nuclear/metabolism , Structure-Activity RelationshipABSTRACT
We describe the discovery of analog 15 (FLG249), which is an orally active and nonsteroidal farnesoid X receptor (FXR) antagonist in mice with unique profiles, such as a propensity for ileum distribution and the significant control in the expression level of three FXR target genes in mouse ileum. Key design features incorporated in 15 were the introduction of metabolically stable groups in potent and metabolically labile antagonist 9. Our pursuit ultimately identified FXR antagonist 15, which has enabled its assessment in a drug discovery program.
ABSTRACT
BACKGROUND AND AIMS: Chronic HBV infection is a major health problem worldwide. Currently, the first-line treatment for HBV is nucleos(t)ide analogs or interferons; however, efficient therapeutic approaches that enable cure are lacking. Therefore, anti-HBV agents with mechanisms distinct from those of current drugs are needed. Sodium taurocholate cotransporting polypeptide (NTCP) was previously identified as an HBV receptor that is inhibited by several compounds. Farnesoid X receptor (FXR) activation also inhibits NTCP function. APPROACH AND RESULTS: In this study, we investigated the inhibitory effect of bile acid (BA) derivatives-namely obeticholic acid (OCA), 6α-ethyl-24-nor-5ß-cholane-3α,7α,23-triol-23 sulfate sodium salt (INT-767; a dual agonist of FXR and Takeda G protein-coupled receptor [TGR5]), and 6α-ethyl-23(S)-methyl-cholic acid (INT-777; a TGR5 agonist)-3-(2,6-dichlorophenyl)-4-(3'-carboxy-2-chlorostilben-4-yl)oxymethyl-5-isopropylisoxazole (GW4064; a FXR agonist), cyclosporin A, and irbesartan. OCA and INT-777 suppressed HBV infection in HepG2-human NTCP-C4 cells. Interestingly, INT-767 showed potent inhibition by attaching to HBV particles rather than binding to NTCP. As an entry inhibitor, INT-767 was stronger than various natural BAs. Furthermore, in chimeric mice with humanized liver, INT-767 markedly delayed the initial rise of HBsAg, HBeAg, and HBV DNA and reduced covalently closed circular DNA. The strong inhibitory effect of INT-767 may be due to the cumulative effect of its ability to inhibit the entry of HBV and to stimulate FXR downstream signaling, which affects the postentry step. CONCLUSIONS: Our results suggest that BA derivatives, particularly INT-767, are prospective candidate anti-HBV agents. Clarifying the underlying mechanisms of BA derivatives would facilitate the development of anti-HBV agents.
Subject(s)
Antiviral Agents/pharmacology , Hepatitis B, Chronic/drug therapy , Receptors, Cytoplasmic and Nuclear/agonists , Receptors, G-Protein-Coupled/agonists , Virus Internalization/drug effects , Animals , Antiviral Agents/therapeutic use , Bile Acids and Salts/pharmacology , Bile Acids and Salts/therapeutic use , Chenodeoxycholic Acid/analogs & derivatives , Chenodeoxycholic Acid/pharmacology , Chenodeoxycholic Acid/therapeutic use , Cholic Acids/pharmacology , Cholic Acids/therapeutic use , Disease Models, Animal , Hep G2 Cells , Hepatitis B virus/drug effects , Hepatitis B virus/metabolism , Hepatitis B, Chronic/virology , Humans , Male , Mice , Organic Anion Transporters, Sodium-Dependent/metabolism , Prospective Studies , Receptors, Cytoplasmic and Nuclear/metabolism , Symporters/metabolism , Transplantation ChimeraABSTRACT
As a cellular bile acid sensor, farnesoid X receptor (FXR) participates in regulation of bile acid, lipid and glucose homeostasis, and liver protection. With respect to the bone metabolism, FXR positively regulates bone metabolism through both bone formation and resorption of the bone remodeling pathways. Some of FXR agonists possessing isoxazole moiety are undergoing clinical trials for the treatment of non-alcoholic steatohepatitis. To date, therefore, the activation of FXR leads to considerable interest in FXR as potential therapeutic targets. We have identified a series of nonsteroidal FXR agonists bearing N1-methyl benzimidazole and isoxazole moieties that are bridged with aromatic derivatives. They showed affinity to FXR, but also weak affinity toward the vitamin D receptor (VDR) that involves regulation of calcium and phosphate homeostasis and is activated by bile acids. The deployment of FXR agonists without activity against VDR as off-target is therefore crucial in the development of FXR ligands. Our efforts focusing on increasing the agonist properties towards FXR led to the discovery of 19, which activates FXR at and below nanomolar levels (EC50 = 26.5 ± 10.5 nM TR-FRET and 0.8 ± 0.2 nM luciferase, respectively) and functions as a FXR agonist: the affinity toward FXR over eight nuclear receptors, including VDR [IC50 (VDR) / EC50 (FXR) > 5000] and TGR5, effects FXR target genes, and activates bone morphogenetic protein-2-induced differentiation of mouse bone marrow-derived mesenchymal stem cell-like ST2 cells into osteoblast.
Subject(s)
Benzimidazoles/pharmacology , Receptors, Calcitriol/antagonists & inhibitors , Receptors, Cytoplasmic and Nuclear/agonists , Benzimidazoles/chemical synthesis , Benzimidazoles/chemistry , Dose-Response Relationship, Drug , Humans , Molecular Structure , Receptors, Calcitriol/metabolism , Structure-Activity RelationshipABSTRACT
BACKGROUND: Prosthetic valve endocarditis (PVE) is a serious complication, and it is difficult to treat marked adhesion and infectious tissue. CASE PRESENTATION: There were four patients with aortic PVE, whose ages ranged from 59 to 80 years. In all patients, transoesophageal echocardiography revealed periannular abscess formation. We applied aortic annular enlargement techniques using a composite three-layer patch to repair the defects after radical debridement of the abscesses, and then replaced the prosthetic valves on the reconstructed annuli. All patients received antibiotics after surgery and recovered well without recurrence. CONCLUSIONS: The aortic annular enlargement techniques provided a good field of vision at the complicated annulus, and our original patch was useful for repairing the aortic annulus and its surrounding apparatus.
Subject(s)
Abscess/surgery , Aortic Valve/surgery , Cardiac Surgical Procedures , Endocarditis, Bacterial/surgery , Heart Valve Prosthesis Implantation/adverse effects , Pericardium/transplantation , Prosthesis-Related Infections/surgery , Abscess/diagnostic imaging , Abscess/microbiology , Aged , Aged, 80 and over , Animals , Aortic Valve/diagnostic imaging , Cattle , Device Removal , Endocarditis, Bacterial/diagnostic imaging , Endocarditis, Bacterial/microbiology , Female , Heterografts , Humans , Male , Middle Aged , Prosthesis-Related Infections/diagnostic imaging , Prosthesis-Related Infections/microbiology , Treatment OutcomeABSTRACT
The modulators of farnesoid X receptor (FXR), a bile acid receptor, regulate various biological processes including bile acid metabolism, and are associated with the control of fatty liver and osteoporosis. Thus, the control of FXR activity and development of FXR modulators are critical not only for research, but also for clinical application. In this study, we synthesized novel FXR agonists 1-4 possessing isoxazole and N-substituted benzimidazole moieties, and compared their effects on osteoblast differentiation with the known FXR agonists, chenodeoxycholic acid and a synthetic compound, GW4064. Two (3 and 4) of the four novel FXR agonists 1-4 showed high specificities for FXR. Computer-assisted modeling suggested that the binding of the FXR agonist 3 with ligand binding domain of FXR was similar to GW4064. FXR was expressed in mouse bone marrow-derived mesenchymal stem cell (MSC)-like ST2 cells (ST-2 MSCs). The FXR agonists activated the BMP-2-induced differentiation of ST-2 MSCs into osteoblasts and enhanced the expression of RUNX2. Moreover, the potency of the FXR agonist 3 was comparable to GW4064 in promoting osteoblast differentiation of ST-2 MSCs. These results indicate that FXR activation enhanced the BMP-2-induced differentiation of MSCs into osteoblasts through activating RUNX2 expression. FXR could be a potential therapeutic target for the treatment of bone diseases such as osteoporosis.
Subject(s)
Cell Differentiation/drug effects , Isoxazoles/chemical synthesis , Isoxazoles/pharmacology , Mesenchymal Stem Cells/cytology , Mesenchymal Stem Cells/drug effects , Osteoblasts/cytology , Receptors, Cytoplasmic and Nuclear/agonists , Animals , Cell Survival/drug effects , Chemistry Techniques, Synthetic , Fluoroimmunoassay , Genes, Reporter , Humans , Isoxazoles/chemistry , Mice , Models, Molecular , Receptors, Cytoplasmic and Nuclear/chemistry , Structure-Activity RelationshipABSTRACT
Antagonizing transcriptional activity of farnesoid X receptor (FXR) in the intestine has been reported as an effective means for the treatment of nonalcoholic fatty liver disease, type 2 diabetes and obesity. We describe herein that the building blocks necessary to maintain the antagonism of our chemotype were investigated in order to modulate in vivo pharmacokinetic behavior and the tissue distribution without blunting the activity against FXR. A comprehensive understanding of the structure-activity relationship led to analog 30, which is superior to 12 in terms of its pharmacokinetic profiles by oral administration and its tissue distribution toward target tissues (liver and ileum) in rats while preserving the in vitro activity of 12 against FXR. Thus, 30 should be a candidate compound to investigate the effects of inhibiting FXR activity while simultaneously improving the outcome of nonalcoholic fatty liver disease, type 2 diabetes and obesity.
Subject(s)
Benzimidazoles/pharmacokinetics , Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors , Administration, Intravenous , Administration, Oral , Animals , Anti-Obesity Agents/administration & dosage , Anti-Obesity Agents/chemical synthesis , Anti-Obesity Agents/pharmacokinetics , Benzimidazoles/administration & dosage , Benzimidazoles/chemical synthesis , Hypoglycemic Agents/administration & dosage , Hypoglycemic Agents/chemical synthesis , Hypoglycemic Agents/pharmacokinetics , Ileum/metabolism , Liver/metabolism , Male , Molecular Structure , Rats, Sprague-Dawley , Structure-Activity RelationshipABSTRACT
Farnesoid X receptor (FXR) plays a major role in the control of cholesterol metabolism. Antagonizing transcriptional activity of FXR is an effective means to treat the relevant metabolic syndrome. Some of antagonists so far have the charged functions; however, they may negatively affect the pharmacokinetics. We describe herein a structure-activity relationship (SAR) exploration of nonacidic FXR antagonist 6 focusing on two regions in the structure and biological evaluation of nonacidic 10 with the characteristic N-acylated piperidine group obtained from SAR studies. As the robust affinity to FXR is feasible with our nonacidic analogue, 10 is among the most promising candidates for in vivo testing.
ABSTRACT
The farnesoid X receptor (FXR) is a major nuclear receptor of bile acids; its activation suppresses sterol regulatory element-binding protein 1c (SREBP1c)-mediated lipogenesis and decreases the lipid contents in the liver. There are many reports showing that the administration of ursodeoxycholic acid (UDCA) suppresses lipogenesis and reduces the lipid contents in the liver of experimental animals. Since UDCA is not recognized as an FXR agonist, these effects of UDCA cannot be readily explained by its direct activation of FXR. We observed that the dietary administration of UDCA in mice decreased the expression levels of SREBP1c and its target lipogenic genes. Alpha- and ß-muricholic acids (MCA) and cholic acid (CA) were the major bile acids in the mouse liver but their contents decreased upon UDCA administration. The hepatic contents of chenodeoxycholic acid and deoxycholic acid (DCA) were relatively low but were not changed by UDCA. UDCA did not show FXR agonistic or antagonistic potency in in vitro FXR transactivation assay. Taking these together, we deduced that the above-mentioned change in hepatic bile acid composition induced upon UDCA administration might cause the relative increase in the FXR activity in the liver, mainly by the reduction in the content of ß-MCA, a farnesoid X receptor antagonist, which suggests a mechanism by which UDCA suppresses lipogenesis and decreases the lipid contents in the mouse liver.
Subject(s)
Lipogenesis/drug effects , Liver/metabolism , Receptors, Cytoplasmic and Nuclear/metabolism , Sterol Regulatory Element Binding Protein 1/genetics , Ursodeoxycholic Acid/administration & dosage , Animals , Cell Line , Chenodeoxycholic Acid/metabolism , Cholic Acids , Deoxycholic Acid/metabolism , Gene Expression Regulation/drug effects , Male , Mice , Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors , Ursodeoxycholic Acid/pharmacologyABSTRACT
We describe here a novel chemotype with substituted benzimidazole scaffold for nonsteroidal farnesoid X receptor (FXR) antagonists starting from the identification of a screening hit, BB-4. Structure diversity in four regions A-D of BB-4 or 1 is discussed. In particular, regions A and C had an effect on an antagonism against FXR as demonstrated by the derivatives represented by 7 and 15, respectively. Thus, compound 19 arising from the combination of regions A and C underscored an important fact on antagonism against FXR, also showing the reduced small heterodimer partner and the increased cholesterol 7α-hydroxylase expression levels.