Over the past decade, there has been increasing attention on the interaction between microbiota and bile acid metabolism. Bile acids are not only involved in the metabolism of nutrients, but are also important in signal transduction for the regulation of host physiological activities. Microbial-regulated bile acid metabolism has been proven to affect many diseases, but there have not been many studies of disease regulation by microbial receptor signaling pathways. This review considers findings of recent research on the core roles of farnesoid X receptor (FXR), G protein-coupled bile acid receptor (TGR5), and vitamin D receptor (VDR) signaling pathways in microbial-host interactions in health and disease. Studying the relationship between these pathways can help us understand the pathogenesis of human diseases, and lead to new solutions for their treatments.
Bile Acids and Salts/metabolism* ; Gastrointestinal Microbiome ; Humans ; Inflammation/metabolism* ; Metabolic Syndrome/metabolism* ; Receptors, Calcitriol/physiology* ; Receptors, Cytoplasmic and Nuclear/physiology* ; Receptors, G-Protein-Coupled/physiology* ; Signal Transduction/physiology*

The function of kidney is maintaining water balance of our body through regulation of urine concentration and dilution. The aquaporins are molecular basis of renal urine production and water transport, and their expression and membrane translocation are regulated delicately. Nuclear receptors are a superfamily of ligand-activated transcription factors consisting of 48 members in human. They widely participate in a variety of physiological and pathophysiological regulation including growth and development, glucose and lipid metabolism, inflammation, immunology by regulating target gene transcription and expression. Increasing evidence demonstrates that these receptors are involved in the regulation of aquaporins expression and membrane translocation in kidney, thereby playing a major role in water homeostasis. Here we review the role of nuclear receptors in regulating renal water transport.
Aquaporins ; physiology ; Biological Transport ; Homeostasis ; Humans ; Kidney ; physiology ; Receptors, Cytoplasmic and Nuclear ; physiology ; Water

OBJECTIVEThis study aimed to investigate the expression pattern and function of Nuclear receptor subfamily 2 group E member 1 (Nr2e1) in retinoic acid (RA)-induced brain abnormality.

METHODSThe mouse model of brain abnormality was established by administering 28 mg/kg RA, and neural stem cells (NSCs) were isolated from the mouse embryo and cultured in vitro. Nr2e1 expression was detected by whole mount in situ hybridization, RT-PCR, and Western blotting. Nr2e1 function was determined by transducing Nr2e1 shRNA into NSCs, and the effect on the sonic hedgehog (Shh) signaling pathway was assessed in the cells. In addition, the regulation of Nr2e1 expression by RA was also determined in vitro.

RESULTSNr2e1 expression was significantly downregulated in the brain and NSCs of RA-treated mouse embryos, and knockdown of Nr2e1 affected the proliferation of NSCs in vitro. In addition, a similar expression pattern of Nr2e1 and RA receptor (RAR) α was observed after treatment of NSCs with different concentrations of RA.

CONCLUSIONOur study demonstrated that Nr2e1 could be regulated by RA, which would aid a better understanding of the mechanism underlying RA-induced brain abnormality.

Animals ; Brain ; cytology ; embryology ; Cell Proliferation ; Down-Regulation ; Gene Expression Regulation ; Gene Expression Regulation, Developmental ; drug effects ; Mice ; Mice, Inbred C57BL ; Neural Stem Cells ; drug effects ; physiology ; Receptors, Cytoplasmic and Nuclear ; genetics ; metabolism ; Tretinoin ; pharmacology

BACKGROUNDStatin therapy has affected glucose homoeostasis of type 2 diabetes patients, which could be related with bile acids metabolism. Whether bile acid metabolism and the expression of farnesoid X receptor (FXR), liver X receptor-α (LXR-α) and sterol regulatory element-binding protein (Srebp)-1c is regulated by hyperglycemia, or whether simvastatin therapy led to higher glucose is related with down-regulated expression of FXR in diabetic rats remained unclear.

METHODSForty male Wistar rats were randomly divided into four groups: normal control rats, insulin resistance rats, diabetic model rats, and the late simvastatin induced diabetic rats. Normal control rats were fed with standard diet, others were fed with high-fat diet. Diabetic model rats were induced by a single intraperitoneal injection of streptozotocin (STZ). The late simvastatin induced diabetic rats started simvastatin administration after STZ induced diabetic model rats. Characteristics of fasting blood glucose (FPG), lipid files and total bile acids (TBAs) were measured and the oral glucose tolerance test (OGTT) was performed after overnight fasting at the eighth weekend. RNA and protein levels of FXR, LXR-α and Srebp-1c were tested by Western blotting and reverse transcription polymerase chain reaction (RT-PCR).

RESULTSThe insulin resistance rats showed higher glucose, lipid files and lower expression of FXR compared with normal control rats (P > 0.05). The diabetic model rats showed significantly higher glucose, lipid files, TBA and lower expression of FXR compared with insulin resistance rats (P < 0.05). The late simvastatin induced diabetic rats displayed higher glucose and TBA and lower expression of FXR compared with diabetic model rats (P < 0.05).

CONCLUSIONSChanges in bile acid homeostasis, including the alterations of bile acid levels and bile acid receptors, are either a cause or a consequence of the metabolic disturbances observed during diabetic models. Statin therapy induced hyperglycemia may be related with FXR, SHP, LXR-α and Srebp-1 pathways.

Animals ; Blood Glucose ; drug effects ; metabolism ; Diabetes Mellitus, Experimental ; drug therapy ; metabolism ; Glucose Tolerance Test ; Homeostasis ; drug effects ; Insulin Resistance ; physiology ; Liver X Receptors ; Male ; Orphan Nuclear Receptors ; metabolism ; Rats ; Rats, Wistar ; Receptors, Cytoplasmic and Nuclear ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Simvastatin ; therapeutic use ; Sterol Regulatory Element Binding Protein 1 ; metabolism

Animals ; Cholestasis ; complications ; Fibrosis ; etiology ; Gallbladder ; pathology ; Humans ; Kidney ; pathology ; Lipid Metabolism ; Liver Cirrhosis ; etiology ; therapy ; Myocardium ; pathology ; Receptors, Cytoplasmic and Nuclear ; physiology

OBJECTIVE: To explore the effects of nuclear protein-like transcription factor nuclear receptor subfamily 2 group E member 1 (NR2E1) on the growth, division, and proliferation of neuroblastoma cell line IMR32. METHODS: A NR2E1 shiRNA plasmid vector was constructed and transfected into neuroblastoma cell line IMR32 using lipofedamine™2000. Subsequent cell growth was measured by cell counting and the protein expression of somatic nuclear division was examined by immunofluorescent staining. RESULTS: At 48 h after the neuroblastoma cells IMR32 were transfected with NR2E1-shiRNA vector, the related nuclear division protein and the proliferation of the transfected cells IMR32 were remarkably depressed. CONCLUSION Cells division and proliferation of neuroblastoma cell line IMR32 is inhibited through transfection with the NR2E1-shiRNA plasmid vector.
Cell Division ; genetics ; physiology ; Cell Line, Tumor ; Cell Proliferation ; Humans ; Neuroblastoma ; pathology ; RNA, Small Interfering ; genetics ; Receptors, Cytoplasmic and Nuclear ; genetics ; metabolism ; Transfection

Nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are originally characterized as transcription factors regulating many target genes. Recent works have revealed that these nuclear receptors play critical roles in regulating genes that encode drug metabolism enzymes and modulating hepatic energy metabolism, such as down-regulating gluconeogenesis, fatty acid oxidation, and ketogenesis, as well as up-regulating lipogenesis. Studies on PXR and CAR have important implication on drug-drug interaction (DDI) and potential disease treatment targets.
Animals ; Drug Interactions ; Energy Metabolism ; Glucose ; metabolism ; Glucose-6-Phosphate ; metabolism ; Humans ; Inflammation ; metabolism ; Lipid Metabolism ; Liver ; metabolism ; NF-kappa B ; metabolism ; Receptors, Cytoplasmic and Nuclear ; physiology ; Receptors, Steroid ; physiology

The nuclear receptors, steroid and xenobiotic receptor (SXR) and constitutive androstane receptor (CAR) play important functions in mediating lipid and drug metabolism in the liver. The present study demonstrates modulatory actions of estrogen in transactivations of SXR-mediated liver X receptor response element (LXRE) and CAR-mediated phenobarbital response element (PBRU). When human estrogen receptor (hERalpha) and SXR were exogenously expressed, treatment with either rifampicin or corticosterone promoted significantly the SXR-mediated transactivation of LXRE reporter gene in HepG2. However, combined treatment with estrogen plus either rifampicin or corticosterone resulted in less than 50% of the mean values of the transactivation by rifampicin or corticosterone alone. Thus, it is suggested that estrogen may repress the SXR-mediated transactivation of LXRE via functional cross-talk between ER and SXR. The CAR-mediated transactivation of PBRU was stimulated by hERalpha in the absence of estrogen. However, the potentiation by CAR agonist, TCPOBOP, was significantly repressed by moxestrol in the presence of ER. Thus, ER may play both stimulatory and inhibitory roles in modulating CAR-mediated transactivation of PBRU depending on the presence of their ligands. In summary, this study demonstrates that estrogen modulates transcriptional activity of SXR and CAR in mediating transactivation of LXRE and PBRU, respectively, of the nuclear receptor target genes through functional cross-talk between ER and the corresponding nuclear receptors.
Corticosterone/pharmacology ; Estrogens/*metabolism ; Ethinyl Estradiol/analogs & derivatives/pharmacology ; Hep G2 Cells ; Humans ; Liver/*metabolism ; Orphan Nuclear Receptors/metabolism ; Phenobarbital/metabolism ; Pyridines/pharmacology ; Receptor Cross-Talk ; Receptors, Cytoplasmic and Nuclear/agonists/*metabolism ; Receptors, Steroid/*metabolism ; Response Elements ; Rifampin/pharmacology ; Transcriptional Activation/*drug effects/physiology

OBJECTIVETo identify and elucidate the vasorelaxant activity of homoisoflavonoids, the main chemical components from Lignum Sappan (the stems of Caesalpinia sappan), in isolated rat thoracic aortic rings pre-contracted with phenylephrine (PE, 1 micromol x L(-1)) and KCl (60 mmol x L(-1)).

METHODThe tension of rat thoracic aorta rings was used to evaluated the vasorelaxant activities of four homoisoflavonoids, brazlin (1), (E)-3-(3,4-dihydroxybenzylidene)-7-hydroxychroman-4-one (2), sappanone B (3), 3-deoxysappanone B (4).

RESULTCumulative addition of homoisoflavonoids (2, 3 and 4) (50-1000 micromol x L(-1)) exhibited an acute relaxation either in endothelium-intact or endothelium-denuded rings in a concentration-dependent manner. However, this relaxation was significantly inhibited in endothelium-denuded condition and in the presence of endothelial nitric oxide synthase (eNOS) inhibitor, N(W)-nitro-L-arginine methyl ester (L-NNA, 100 micromol x L(-1)), and a soluble guanylate cylcase (sGC) inhibitor, methylene blue (MB, 10 micromol x L(-1)) when addition of variation homoisoflavonoids brazlin (1) (50-1000 micromol x L(-1)).

CONCLUSIONThese results indicate that normo-homoisoflavonoids (2, 3 and 4) from Caesalpinia sappan mediates endothelium-independent vasodilator action in rat thoracic aortic rings, while the variation homoisoflavonoids brazlin elicits endothelium-dependent relaxation might via nitric oxide (NO)-cGMP pathway. This research could explain the pharmacological activities of homoisoflavonoids to a certain degree.

Animals ; Aorta, Thoracic ; drug effects ; physiology ; Caesalpinia ; chemistry ; Endothelium ; metabolism ; Enzyme Inhibitors ; pharmacology ; Flavonoids ; chemistry ; pharmacology ; Guanylate Cyclase ; antagonists & inhibitors ; Male ; Muscle Contraction ; drug effects ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide Synthase Type III ; antagonists & inhibitors ; Phenylephrine ; pharmacology ; Potassium Chloride ; pharmacology ; Rats ; Receptors, Cytoplasmic and Nuclear ; antagonists & inhibitors ; Soluble Guanylyl Cyclase ; Vasodilation ; drug effects ; Vasodilator Agents ; chemistry ; pharmacology

Animals ; Apoptosis ; Cell Cycle ; Cell Cycle Proteins ; genetics ; metabolism ; physiology ; DNA Repair ; Homeodomain Proteins ; genetics ; metabolism ; physiology ; Humans ; Inhibitor of Growth Protein 1 ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; physiology ; Neoplasm Metastasis ; Neoplasms ; metabolism ; pathology ; Neovascularization, Pathologic ; pathology ; Nuclear Proteins ; genetics ; metabolism ; physiology ; Prognosis ; Receptors, Cytoplasmic and Nuclear ; genetics ; metabolism ; physiology ; Signal Transduction ; Transcription Factors ; genetics ; metabolism ; physiology ; Tumor Suppressor Protein p53 ; metabolism ; Tumor Suppressor Proteins ; chemistry ; genetics ; metabolism ; physiology