Endogenously eliminating the hematoma is a favorable strategy in addressing intracerebral hemorrhage (ICH). This study sought to determine the role of retinoid X receptor-α (RXR-α) in the context of hematoma absorption after ICH. Our results showed that pharmacologically activating RXR-α with bexarotene significantly accelerated hematoma clearance and alleviated neurological dysfunction after ICH. RXR-α was expressed in microglia/macrophages, neurons, and astrocytes. Mechanistically, bexarotene promoted the nuclear translocation of RXR-α and PPAR-γ, as well as reducing neuroinflammation by modulating microglia/macrophage reprograming from the M1 into the M2 phenotype. Furthermore, all the beneficial effects of RXR-α in ICH were reversed by the PPAR-γ inhibitor GW9662. In conclusion, the pharmacological activation of RXR-α confers robust neuroprotection against ICH by accelerating hematoma clearance and repolarizing microglia/macrophages towards the M2 phenotype through PPAR-γ-related mechanisms. Our data support the notion that RXR-α might be a promising therapeutic target for ICH.
Anilides/pharmacology* ; Cerebral Hemorrhage/drug therapy* ; Hematoma/drug therapy* ; Humans ; Macrophages ; Microglia ; Neuroprotection ; PPAR gamma ; Retinoid X Receptor alpha

The aim of this study was to investigate the regulatory role of retinoid X receptor (RXR)-mediated oxidative stress pathway in rat pulmonary ischemia/reperfusion injury (PIRI) and the underlying mechanism. Seventy-seven male Sprague-Dawley (SD) rats were randomly divided into 7 groups (n = 11): control group, sham group, sham+9-cis-retinoid acid (9-cRA, RXR agonist) group, sham+HX531 (RXR inhibitor) group, ischemia/reperfusion (I/R) group, I/R+9-cRA group, and I/R+HX531 group. The unilateral lung I/R model was established by obstruction of left lung hilus for 30 min and reperfusion for 180 min in vivo. The rats in I/R+9-cRA and I/R+HX531 groups were given intraperitoneal injection of 9-cRA and HX531 before thoracotomy. After reperfusion, the left lung tissue was taken to evaluate the lung tissue injury, and the oxidative stress-related indexes of the lung tissue were detected by the corresponding kits. The lung tissue morphology and the ultrastructure of the alveolar epithelial cells were observed by HE staining and transmission electron microscope, respectively. The protein expression of RXR in lung tissue was observed by immunofluorescence labeling method, and the expression level of nuclear factor E2-related factor (Nrf2) protein was detected by Western blot. The results showed that, compared with the sham group, the I/R group exhibited obviously injured lung tissue, decreased SOD activity, increased MDA content and MPO activity, and down-regulated expression level of Nrf2 protein. Compared with the I/R group, the I/R+9-cRA group showed alleviated lung tissue injury, increased activity of SOD, decreased MDA content and MPO activity, and up-regulated expression levels of RXR and Nrf2 protein. The above-mentioned improvement effects of 9-cRA were reversed by HX531 treatment. These results suggest that RXR activation can effectively protect the lung tissue against I/R injury, and the mechanism may involve the activation of Nrf2 signaling pathway, the enhancement of antioxidant level and the reduction of oxidative stress response.
Animals ; Lung ; physiopathology ; Male ; NF-E2-Related Factor 2 ; physiology ; Oxidative Stress ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; Retinoid X Receptors ; physiology ; Signal Transduction

Retinoid X receptor α (RXRα) and its N-terminally truncated version tRXRα play important roles in tumorigenesis, while some RXRα ligands possess potent anti-cancer activities by targeting and modulating the tumorigenic effects of RXRα and tRXRα. Here we describe NSC-640358 (N-6), a thiazolyl-pyrazole derived compound, acts as a selective RXRα ligand to promote TNFα-mediated apoptosis of cancer cell. N-6 binds to RXRα and inhibits the transactivation of RXRα homodimer and RXRα/TR3 heterodimer. Using mutational analysis and computational study, we determine that Arg316 in RXRα, essential for 9-cis-retinoic acid binding and activating RXRα transactivation, is not required for antagonist effects of N-6, whereas Trp305 and Phe313 are crucial for N-6 binding to RXRα by forming extra π-π stacking interactions with N-6, indicating a distinct RXRα binding mode of N-6. N-6 inhibits TR3-stimulated transactivation of Gal4-DBD-RXRα-LBD by binding to the ligand binding pocket of RXRα-LBD, suggesting a strategy to regulate TR3 activity indirectly by using small molecules to target its interacting partner RXRα. For its physiological activities, we show that N-6 strongly inhibits tumor necrosis factor α (TNFα)-induced AKT activation and stimulates TNFα-mediated apoptosis in cancer cells in an RXRα/tRXRα dependent manner. The inhibition of TNFα-induced tRXRα/p85α complex formation by N-6 implies that N-6 targets tRXRα to inhibit TNFα-induced AKT activation and to induce cancer cell apoptosis. Together, our data illustrate a new RXRα ligand with a unique RXRα binding mode and the abilities to regulate TR3 activity indirectly and to induce TNFα-mediated cancer cell apoptosis by targeting RXRα/tRXRα.
Apoptosis ; drug effects ; Cell Line, Tumor ; Enzyme Activation ; drug effects ; Humans ; Ligands ; Molecular Docking Simulation ; Nuclear Receptor Subfamily 4, Group A, Member 1 ; genetics ; metabolism ; Oximes ; metabolism ; pharmacology ; Protein Conformation ; Proto-Oncogene Proteins c-akt ; metabolism ; Pyrazoles ; metabolism ; pharmacology ; Retinoid X Receptor alpha ; chemistry ; genetics ; metabolism ; Thiazoles ; metabolism ; pharmacology ; Transcription, Genetic ; drug effects ; Transcriptional Activation ; drug effects ; Tumor Necrosis Factor-alpha ; metabolism

BACKGROUND AND OBJECTIVES: Excretion of bile acid and free cholesterol of bile was important to maintain cholesterol homeostasis. ATP-binding cassette transporter G5 (ABCG5) and G8 (ABCG8) promoted biliary cholesterol excretion. In previous study, hepatic secretion of cholesterol and ABCG5/G8 expression are strongly stimulated in hypophysectomized rats during treatment with thyroid hormone. In this study, we aimed to evaluate the effect of thyroid hormone to expression of ABCG5 and G8 in mouse liver. MATERIALS AND METHODS: We administered thyroid hormone (T3) to C57BL/6 mice and then RNA and protein was isolated from liver. We isolated primary hepatocyte and administered T3 to evaluate in vitro effect. HepG2 cells were cotransfected with either a control plasmid or expression plasmids for human thyroid hormone receptor (hTR)beta/human retinoid X receptor (hRXR)alpha or human liver X receptor (hLXR)alpha in combination with reporter plasmids TK-LXRE3-LUC with or without T3. RESULTS: Serum total cholesterol was decreased after 5 days of T3 treatment. Expression of ABCG5/8 mRNA and ABCG5 protein was increased after T3 treatment. In primary hepatocytes, T3 also increased ABCG5/8 mRNA expression. LXRalpha mRNA was not increased by T3. However, when we cotransfected liver X receptor response element (LXRE) construct and TRbeta/RXRalpha with T3, the activity of LXRE containing construct was markedly increased. CONCLUSION: We confirmed that thyroid hormone increased expression of ABCG5/8. This result suggested that thyroid hormone played an important role in decreasing serum cholesterol through bile excretion.
Animals ; Bile ; Cholesterol ; Hep G2 Cells ; Hepatocytes ; Homeostasis ; Humans ; Liver ; Mice ; Orphan Nuclear Receptors ; Plasmids ; Rats ; Receptors, Thyroid Hormone ; Response Elements ; Retinoid X Receptors ; RNA ; RNA, Messenger ; Thyroid Gland ; Thyroid Hormones

The mechanisms by which emodin induces apoptosis and inhibits proliferation of cancer cells remain unclear. In this study, we investigated whether the proapoptotic effect of emodin on human NIH-H460 lung cancer cells and SMMC-7721 liver cancer cells was related to regulating RXR expression and function. MTT assay and DAPI staining were used to detect the anti-proliferative and apoptotic effects of emodin with or without 9-cis-retinoid acid on H460 and SMMC-7721. The reporter assay was used to detect the effect of emodin on RXR homo- and hetero-dimer transactivation. Competitive ligand binding assay was carried out to detect whether emodin could directly bind to RXR. The result showed that emodin could strongly inhibit the proliferation and induce apoptosis of both cancer cell lines, which could be antagonized by 9-cis-RA. The reporter assay showed that emodin could inhibit the transcriptional effect of the homo- and hetero-dimer transactivation of RXRalpha dose-dependently. However, in vitro binding assay did not show that emodin bind to RXRalpha-LBD directly. The findings suggest that exhibition of emodin its anti-cancer activity may be associated with involvement of RXRalpha signal transduction pathways.
Apoptosis ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Dose-Response Relationship, Drug ; Emodin ; metabolism ; pharmacology ; Humans ; Retinoid X Receptor alpha ; metabolism ; Signal Transduction ; drug effects ; Transcriptional Activation ; drug effects ; Tretinoin ; antagonists & inhibitors

The growth inhibitory effects of four retinoic acid (RA) derivatives, 9-cis RA, 13-cis RA, N-(4-hydroxyphenyl) retinamide (4-HPR), and all-trans retinoic acid (ATRA) were compared. In addition, the effects of various combinations of these four agents were examined on non-small cell lung carcinoma (NSCLC) cell-lines, and on the expressions of retinoic acid receptors (RARs) and retinoid X receptors (RXRs) on these cells. At the clinically achievable concentration of 1 micrometer, only 4-HPR inhibited the growths of H1299 and H460 cells-lines. However, retinoic acid receptor beta(RAR beta) expression was up-regulated on H460 and H1299 cells treated with 1 micrometer of ATRA, 13-cis RA, or 9-cis RA. All NSCLC cell lines showed growth inhibition when exposed sequentially to 1 micrometer ATRA and 0.1 micrometer 4-HPR. In particular, sequential treatment with 1 micrometer ATRA or 13-cis RA and 4-HPR markedly inhibited H1703 cell growth; these cells exhibited no basal RAR beta expression and were refractory to 4-HPR. However, in NSCLC cell lines that expressed RAR beta, the expressional levels of RAR beta were up-regulated by ATRA alone and by sequential treatment with ATRA and 4-HPR. 4-HPR was found to be the most active of the four agents in terms of NSCLC growth-inhibition. Moreover, sequential treatments with ATRA or 13-cis RA followed by 4-HPR were found to have synergistic growth-inhibitory effects and to regulate RAR expression.
Base Sequence ; Carcinoma, Non-Small-Cell Lung/*drug therapy/genetics/metabolism ; Cell Line, Tumor ; DNA Primers/genetics ; Drug Therapy, Combination ; Fenretinide/administration & dosage ; Gene Expression/drug effects ; Humans ; Isotretinoin/administration & dosage ; Lung Neoplasms/*drug therapy/genetics/metabolism ; Receptors, Retinoic Acid/genetics ; Retinoid X Receptors/genetics ; Tretinoin/administration & dosage/*analogs & derivatives

OBJECTIVETo investigate the effect and related mechanism of retinoid X receptor (RXR) activation on oxidized low-density lipoprotein (ox-LDL) induced differentiation of macrophage into dendritic cell.

METHODSRAW264.7 murine macrophage cell line was cultured with ox-LDL for 48 h in the absence and presence of RXR activator 9-cisRA or SR11237. Cell morphology was observed by phase contrast microscope and cell surface markers involved in dendritic cell immune maturation and activation was analyzed by FACS. Cellular reactive oxygen species production was detected by CM-H2DCFDA fluorescent probe.

RESULTSox-LDL-treated RAW264.7 murine macrophage cell line differentiated into dendritic like cells after 48 h and cell surface markers CD40, CD86, CD83, MHC Class II and CD1d were upregulated. These changes could be attenuated by cotreatment with 9-cisRA or SR11237. Upregulated cell surface markers CD40, CD86, CD83, MHC Class II and CD1d by ox-LDL were decreased about 47%, 43%, 48%, 32% and 17% respectively by 9-cisRA and 38%, 38%, 46%, 36% and 32% respectively by SR11237. The effect of 9-cisRA and SR11237 was dose dependent. Cellular reactive oxygen species were significantly increased in ox-LDL-treated RAW264.7 cells (MFI 38.24 +/- 4.20 vs. 4.46 +/- 0.39, P < 0.05) and which was significantly reduced by 9-cisRA (10(-7) mol/L) and SR11237 (10(-6) mol/L) to 12.60 +/- 1.52 and 17.89 +/- 1.91 respectively (all P < 0.05).

CONCLUSIONRXR activation partly inhibits the differentiation of ox-LDL induced macrophage into dendritic cell by reducing oxidative stress injury.

Animals ; Benzoates ; pharmacology ; Cell Differentiation ; drug effects ; Cell Line ; Dendritic Cells ; cytology ; drug effects ; Lipoproteins, LDL ; metabolism ; Macrophages ; cytology ; drug effects ; Mice ; Retinoid X Receptors ; metabolism ; Retinoids ; pharmacology ; Tretinoin ; pharmacology

OBJECTIVETo apply linkage disequilibrium (LD) maps to associations studies with high throughput single nucleotide polymorphisms (SNPs).

METHODSSeven hundred and fifty-four SNPs were genotyped in 160 Shanghai Chinese. LD maps were constructed in cases and controls separately. By comparing the decline of LD unit with distance between the two groups, disease susceptible loci were estimated. This method was compared with traditional analyses including LD analysis, single SNP and haplotype analyses.

RESULTSThe analysis of LD maps could detect the chromosome regions with different LD patterns between the cases and controls. The alleles and/or haplotypes frequencies of SNPs within the regions had significantly different distributions or trends of significantly different distributions.

CONCLUSIONThis method may be applied to analyze the data from association studies with high throughput SNPs genotype information.

Adult ; Aged ; Case-Control Studies ; DNA-Binding Proteins ; genetics ; Diabetes Mellitus, Type 2 ; genetics ; Female ; Gene Frequency ; Genome-Wide Association Study ; methods ; Haplotypes ; Humans ; Linkage Disequilibrium ; Male ; Polymorphism, Single Nucleotide ; Pre-B-Cell Leukemia Transcription Factor 1 ; Proto-Oncogene Proteins ; genetics ; Retinoid X Receptor gamma ; genetics

Animals ; Antineoplastic Agents ; chemical synthesis ; chemistry ; pharmacology ; Humans ; Ligands ; Neoplasms ; pathology ; Retinoid X Receptors ; agonists ; chemistry ; pharmacology ; Retinoids ; chemical synthesis ; chemistry ; pharmacology ; Structure-Activity Relationship ; Tetrahydronaphthalenes ; chemical synthesis ; chemistry ; pharmacology ; Tretinoin ; chemical synthesis ; chemistry ; pharmacology

Apoptosis ; Caspase 3 ; Caspases ; physiology ; Cell Line, Tumor ; Cell Proliferation ; Humans ; Isotretinoin ; pharmacology ; Melanoma ; pathology ; Receptors, Retinoic Acid ; physiology ; Retinoid X Receptors ; physiology ; Tretinoin ; pharmacology