Peroxisome proliferation is a cellular response to many chemical compounds affects including natural and modified fatty acids, phthalate and adipate ester plasticizers, leukotriene antagonists, acetylsalicylic acid and certain pathophysiological conditions including dramatic change of cellular morphology and enzymatic activity. Peroxisome proliferation phenomenon is seen primarily in liver and kidney. Hormones and nutritional factor can regulate peroxisome proliferation response. Sustained peroxisome proliferation can lead to hepatocarcinogenesis. The three types of peroxisome proliferator activated receptor, termed PPAR alpha, PPAR beta, and PPAR gamma, expressed in specific tissue, are consisted of a specific a nuclear receptor superfamily. After more than 10 years world wide research, the function of PPAR is clarified, as PPAR gamma, the master of thrifty genes, controls the expression of genes relative to adipogenesis, diabetes mellitus and obesity. The receptor is involved in transcriptional control of numerous cellular processes including cell cycle control, inflammation, immunoregulation and carcinogenesis.
Adipocytes ; cytology ; Animals ; Cell Differentiation ; Energy Metabolism ; genetics ; Humans ; Intracellular Signaling Peptides and Proteins ; Nuclear Receptor Coactivators ; Peroxisome Proliferators ; Receptors, Cytoplasmic and Nuclear ; genetics ; physiology ; Transcription Factors ; genetics ; physiology

The constitutive androstane receptor (CAR, NR1I3) plays a crucial role in the regulation of drug metabolism, energy homeostasis, and cancer development through modulating the transcription of its numerous target genes. Different from prototypical nuclear receptors, CAR can be activated by either direct ligand binding or ligand-independent (indirect) mechanisms both initiated with nuclear translocation of CAR from the cytoplasm. In comparison to the well-defined ligand-based activation, indirect activation of CAR appears to be exclusively involved in the nuclear translocation through mechanisms yet to be fully understood. Accumulating evidence reveals that without activation, CAR forms a protein complex in the cytoplasm where it can be functionally affected by multiple signaling pathways. In this review, we discuss recent progresses in our understanding of the signaling regulation of CAR nuclear accumulation and activation. We expect that this review will also provide greater insight into the similarity and difference between the mechanisms of direct vs. indirect human CAR activation.
Active Transport, Cell Nucleus ; genetics ; Cytoplasm ; metabolism ; Hepatocytes ; metabolism ; Humans ; Ligands ; Protein Transport ; genetics ; Receptors, Cytoplasmic and Nuclear ; genetics ; metabolism ; Signal Transduction ; genetics

OBJECTIVETo investigate the gene expression of osteoprotegerin (OPG) and osteoclast differentiation factor (ODF/TRANCE/RANKL), two new members of the TNF-receptor superfamily, in giant cell tumor (GCT); to discuss the molecular mechanism of extensive bone resorption caused by GCT.

METHODSUsing TRIzol reagent to prepare total RNA from GCT sample and normal bone tissue. By a first-strand complementary DNA (cDNA) synthesis kit, cDNA was synthesized from 2.0 micro g RNA according to the manufacturer's instructions. cDNA was then amplified by PCR. Amplification products were resolved by electrophoresis on a 1.5% agarose gel and stained with EB. The relative quantity of the PCR products were determined and the mRNA levels of OPG, ODF, M-CSF (cofactor of ODF), and RANK (receptor of ODF) were compared with that of the normal bone.

RESULTSGCT contained highly expressed mRNA of ODF, OPG, M-CSF and RANK. There was mRNA expression of OPG, M-CSF and RANK and less expression of ODF in normal bone. The ODF mRNA and RANK mRNA in GCT were more abundant than that in normal bone. In GCT, the ratio of ODF mRNA exceeded OPG expression. But in normal bone, the OPG mRNA exceeded ODF expression.

CONCLUSIONSThe results suggest that GCT contains all signals including OPG, ODF, M-CSF and RANK that are essential for inducing osteoclastogenesis and promoting bone resorption.

Carrier Proteins ; genetics ; Gene Expression Regulation, Neoplastic ; Giant Cell Tumor of Bone ; genetics ; pathology ; Glycoproteins ; genetics ; Humans ; Membrane Glycoproteins ; genetics ; Osteoprotegerin ; RANK Ligand ; RNA, Messenger ; genetics ; metabolism ; Receptor Activator of Nuclear Factor-kappa B ; Receptors, Cytoplasmic and Nuclear ; genetics ; Receptors, Tumor Necrosis Factor

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

AIMTo investigate the roles of liver X receptors (LXR) in the lipid composition and gene expression regulation in the murine caput epididymidis. LXR are nuclear receptors for oxysterols, molecules derived from cholesterol metabolism that are present in mammals as two isoforms: LXRalpha, which is more specifically expressed in lipid-metabolising tissues, such as liver, adipose and steroidogenic tissues, and macrophages, whereas LXRbeta is ubiquitous. Their importance in reproductive physiology has been sustained by the fact that male mice in which the function of both LXR has been disrupted have fertility disturbances starting at the age of 5 months, leading to complete sterility by the age of 9 months. These defects are associated with epididymal epithelial degeneration in caput segments one and two, and with a sperm midpiece fragility, leading to the presence of isolated sperm heads and flagella when luminal contents are recovered from the cauda epididymidis.

METHODSThe lipid composition of the caput epididymidis of wild-type and LXR-deficient mice was assessed using oil red O staining on tissue cryosections and lipid extraction followed by high performance liquid chromatography or gas chromatography. Gene expression was checked by quantitative real time polymerase chain reaction.

RESULTSUsing LXR-deficient mice, we showed an alteration of the lipid composition of the caput epididymidis as well as a significantly decreased expression of the genes encoding SREBP1c, SCD1 and SCD2, involved in fatty acid metabolism.

CONCLUSIONAltogether, these results show that LXR are important regulators of epididymal function, and play a critical role in the lipid maturation processes occurring during sperm epididymal maturation.

Animals ; DNA Primers ; DNA-Binding Proteins ; deficiency ; genetics ; physiology ; Epididymis ; cytology ; physiology ; Epithelial Cells ; physiology ; Fatty Acids ; metabolism ; Homeostasis ; Lipids ; physiology ; Liver X Receptors ; Male ; Mice ; Mice, Knockout ; Orphan Nuclear Receptors ; Polymerase Chain Reaction ; Receptors, Cytoplasmic and Nuclear ; deficiency ; genetics ; physiology

OBJECTIVETo investigate the existence of alternatively spliced variants of constitutive androstane receptor (CAR) in liver of mouse.

METHODSThe nucleotide from liver of mouse was purified and the CAR cDNA was amplified by PCR. The fragments of CAR cDNA were cloned to T vector and sequence analysis was performed.

RESULTVarious spliced variants of CAR in liver mouse were confirmed by DNA sequencing.

CONCLUSIONThere are alternatively spliced variants in CAR, which are located in the ligand binding sequence of CAR.

Alternative Splicing ; Amino Acid Sequence ; Animals ; DNA, Complementary ; genetics ; Liver ; metabolism ; Male ; Mice ; Molecular Sequence Data ; RNA Splice Sites ; Receptors, Cytoplasmic and Nuclear ; genetics

Carboxylesterases (CESs) play important roles in the metabolism of endogenous and foreign compounds in physiological and pharmacological responses. The aim of this study was to investigate the effect of dexamethasone at different doses on the expression of CES1 and CES2. Imidapril and irinotecan hydrochloride (CPT-11) were used as special substrates for CES1 and CES2, respectively. Rat hepatocytes were cultured and treated with different concentrations of dexamethasone. The hydrolytic activity of CES1 and CES2 was tested by incubation experiment and their expression was quantitated by real-time PCR. A pharmacokinetic study was conducted in SD rats to further evaluate the effect of dexamethasone on CESs activity in vivo. Western blotting was performed to investigate the regulatory mechanism related to pregnane X receptor (PXR) and glucocorticoid receptor (GR). The results showed that exposure of cultured rat hepatocytes to nanomolar dexamethasone inhibited the imidapril hydrolase activity, which was slightly elevated by micromolar dexamethasone. For CES2, CPT-11 hydrolase activity was induced only when dexamethasone reached micromolar levels. The real-time PCR demonstrated that CES1 mRNA was markedly decreased by nanomolar dexamethasone and increased by micromolar dexamethasone, whereas CES2 mRNA was significantly increased by micromolar dexamethasone. The results of a complementary animal study showed that the concurrent administration of dexamethasone significantly increased the plasma concentration of the metabolite of imidapril while the ratio of CPT-11 to its metabolite SN-38 was significantly decreased. PXR protein was gradually increased by serial concentrations of dexamethasone. However, only nanomolar dexamethasone elevated the level of GR protein. The different concentrations of dexamethasone required suggested that suppression of CES1 may be mediated by GR whereas the induction of CES2 may result from the role of PXR. It was concluded that dexamethasone at different concentrations can differentially regulate CES1 and CES2.
Animals ; Carboxylic Ester Hydrolases ; genetics ; Dexamethasone ; pharmacology ; Gene Expression ; drug effects ; immunology ; Male ; Rats ; Rats, Sprague-Dawley ; Receptors, Cytoplasmic and Nuclear ; metabolism

Small heterodimer partner (SHP) is an atypical member of nuclear receptor superfamily that lacks a DNA-binding domain. In previous study, we showed that SHP, c-jun, p65 of NF-kappaB subunits, and p21WAF1 expression was increased during monocytic differentiaton with the exposure of human leukemia cells to a differentiation agent, PMA. In this study, c-Jun and p65 were shown to mediate the transcriptional activation of the SHP promoter. In addition, SHP induced the cell cycle regulatory protein levels and cooperatively increased an induction of p21WAF1 expression with p65. Furthermore, SHP protected differentiated cells from etoposide-induced cellular apoptosis through the induction and cytoplasmic sequestration of p21WAF1. Complex formation between SHP and p21WAF1 was demonstrated by means of coimmunoprecipitation. These results suggest that SHP prolongs a cellular survival of differentiating monocytes through the transcriptional regulation of target genes of cell survival and differentiation.
*Apoptosis ; Cell Differentiation ; Cell Line, Tumor ; Cyclin-Dependent Kinase Inhibitor p21/genetics/*metabolism ; Gene Expression Regulation ; Humans ; Monocytes/cytology ; Promoter Regions, Genetic ; Proto-Oncogene Proteins c-jun/genetics/metabolism ; Receptors, Cytoplasmic and Nuclear/genetics/*metabolism ; Transcription Factor RelA/genetics/metabolism

This study is purposed to investigate the effects of praeruptorin A (PA) and praeruptorin C (PC) on UGT1A1 in HepG2 cells through hCAR pathway. PA and PC were incubated with HepG2 cells for 24 h and 48 h, mRNA and protein expressions of UGT1A1 were determined by real-time PCR and Western blotting assays. Additionally, effects of PA and PC on UGT1A1 mRNA and protein expressions were also measured after transient transfection of a specific CAR siRNA for 72 h in HepG2 cells. UGT1A1 mRNA and protein expression levels were significantly increased by PA and PC after incubation for 48 h. Moreover, the mRNA and protein up-regulations of UGT1A1 were attenuated by transient transfection of a specific CAR siRNA, suggesting the induction was mediated by CAR. The results suggest that PA and PC can significantly up-regulate UGT1A1 expression partially via the CAR-mediated pathway.
Apiaceae ; chemistry ; Coumarins ; isolation & purification ; pharmacology ; Drugs, Chinese Herbal ; pharmacology ; Glucuronosyltransferase ; genetics ; metabolism ; Hep G2 Cells ; Humans ; Plant Roots ; chemistry ; Plants, Medicinal ; chemistry ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; genetics ; metabolism ; Receptors, Cytoplasmic and Nuclear ; genetics ; metabolism ; Signal Transduction ; Transfection

OBJECTIVETo investigate the effects and mechanism of farnesoid X receptor (FXR) and its ligands on the metabolism of bile acids in rats with estrogen-induced intrahepatic cholestasis of pregnancy (ICP).

METHODSAn ICP rat model was established with estradiol benzoate (EB) injections. Then FXR ligand chenodeoxycholic acid (CDCA) was administrated (100 mg/kg daily) to ICP rats for 5 days. The serum TBA and expression of FXR and bile salt export pump (BSEP) in the rat livers were examined by immunohistochemistry and reverse transcription PCR.

RESULTSThe levels of TBA in the CDCA group rats were significantly lower than the untreated rats [(17.2+/-4.1)micromol/L vs (29.3+/-6.4)micromol/L], and the expressions of mRNA and protein of FXR were significantly higher [(0.76+/-0.09 vs 0.53+/-0.06, P<0.05 and 2.35+/-0.06 vs 1.83+/-0.05, P<0.017, respectively)], and the expressions of BSEP were also higher [(0.99+/-0.21 vs 0.76+/-0.07, P<0.017 and 1.88+/-0.03 vs 1.46+/-0.06, P<0.017, respectively)].

CONCLUSIONSFXR plays an important role in modulating the metabolism of bile acids. CDCA can lower the levels of serum TBA by upregulating the expression of FXR and BSEP and then increasing the transport of the bile acids. These facts might present a new idea and target for the treatment of ICP.

Animals ; Bile Acids and Salts ; metabolism ; Chenodeoxycholic Acid ; pharmacology ; Cholestasis, Intrahepatic ; chemically induced ; genetics ; metabolism ; Estrogens ; pharmacology ; Female ; Pregnancy ; Pregnancy Complications ; chemically induced ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Cytoplasmic and Nuclear ; agonists