OBJECTIVES: To study the mechanism of retinoic acid receptor α (RARα) signal change to regulate neurexin 1 (NRXN1) in the visual cortex and participate in the autistic-like behavior in rats with vitamin A deficiency (VAD). METHODS: The models of vitamin A normal (VAN) and VAD pregnant rats were established, and some VAD maternal and offspring rats were given vitamin A supplement (VAS) in the early postnatal period. Behavioral tests were performed on 20 offspring rats in each group at the age of 6 weeks. The three-chamber test and the open-field test were used to observe social behavior and repetitive stereotyped behavior. High-performance liquid chromatography was used to measure the serum level of retinol in the offspring rats in each group. Electrophysiological experiments were used to measure the long-term potentiation (LTP) level of the visual cortex in the offspring rats. Quantitative real-time PCR and Western blot were used to measure the expression levels of RARα, NRXN1, and N-methyl-D-aspartate receptor 1 (NMDAR1). Chromatin co-immunoprecipitation was used to measure the enrichment of RARα transcription factor in the promoter region of the NRXN1 gene. RESULTS: The offspring rats in the VAD group had autistic-like behaviors such as impaired social interactions and repetitive stereotypical behaviors, and VAS started immediately after birth improved most of the behavioral deficits in offspring rats. The offspring rats in the VAD group had a significantly lower serum level of retinol than those in the VAN and VAS groups (P<0.05). Compared with the offspring rats in the VAN and VAS groups, the offspring rats in the VAD group had significant reductions in the mRNA and protein expression levels of NMDAR1, RARα, and NRXN1 and the LTP level of the visual cortex (P<0.05). The offspring rats in the VAD group had a significant reduction in the enrichment of RARα transcription factor in the promoter region of the NRXN1 gene in the visual cortex compared with those in the VAN and VAS groups (P<0.05). CONCLUSIONS RARα affects the synaptic plasticity of the visual cortex in VAD rats by regulating NRXN1, thereby participating in the formation of autistic-like behaviors in VAD rats.
Animals ; Autistic Disorder ; Female ; Pregnancy ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; Retinoic Acid Receptor alpha ; Visual Cortex ; Vitamin A ; Vitamin A Deficiency

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

Retinoic acid, an active metabolite of vitamin A, exerts multiple effects on regulating embryonic development and inducing differentiation, proliferation, apoptosis as well as resistance in various cancer cells. Apart from the classic genomic action (binding to the nuclear receptors to regulate the expression of its downstream target genes), retinoic acids also play important roles in anti-cancer effect through non-genomic pathways (via extranuclear and non-transcriptional effects).
Apoptosis ; Cell Differentiation ; Genomics ; Humans ; Neoplasms ; drug therapy ; Receptors, Retinoic Acid ; Tretinoin

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

Humans ; Leukemia, Promyelocytic, Acute ; genetics ; Oncogene Proteins, Fusion ; genetics ; Receptors, Retinoic Acid ; genetics ; Retinoic Acid Receptor alpha ; STAT5 Transcription Factor ; genetics

OBJECTIVETo explore the effects of TBLR1-RAR&alpha; on the differentiation induction of leukemia cell line K562 cells into erythroid lineage and to investigate its related mechanisms.

METHODSTet-Off inducible system was used to construct the conditional expression vector of TBLR1-RAR&alpha; fusion gene by cloning the TBLR1-RAR&alpha; fragment into lentivirus vector pLVX-Tight-Puro, the expression of TBLR1-RAR&alpha; fusion gene was induced by doxycycline (Dox). Then, K562 cells were transfected with lentivirus pLVX-Tight-Puro-TBLR1-RAR&alpha;-flag, and the expression of fusion proteins was verified by Western blot. After treatment of K562 with all-trans retinoid acid (ATRA), real time RT-PCR was performed to test the expression of erythroid differentiation-related CD71 and &alpha;, ε, &gamma;-globins gene. Flow cytometry was used also to analyze the expression of erythroid differentiation markers CD71 and CD235a. Benzidine staining was used to detect the production of hemoglobin in K562 cells.

RESULTSqRT-RCR showed that ATRA could increase the expression level of CD71 and &alpha;, ε, &gamma;-globin genes when TBLR1-RAR&alpha; was expressed. After treatment of ATRA, the proportion of CD71(+) cells detected by the flow cytometry also increased. Benzidine staining showed that ATRA could induce hemoglobin production in K562 cells with TBLR1-RAR&alpha; fusion gene expression.

CONCLUSIONThe expression of TBLR1-RAR&alpha; fusion gene contribute to ATRA-inducing differentiation of K562 cells into erythroid lineage.

Cell Differentiation ; Erythrocytes ; Hemoglobins ; Humans ; K562 Cells ; Nuclear Proteins ; Receptors, Cytoplasmic and Nuclear ; Receptors, Retinoic Acid ; Repressor Proteins ; Retinoic Acid Receptor alpha ; gamma-Globins

This study was aimed to investigate the mechanism of all-trans retinoic acid (ATRA) up-regulating apelin expression in vascular smooth muscle cells (VSMCs). The effect of ATRA on apelin expression in the VSMCs was investigated by RT-PCR, real-time PCR and Western blot analysis. To further define whether retinoic acid receptor &alpha; (RAR&alpha;) mediated the induction of apelin by ATRA, endogenous RAR&alpha; was down regulated by transfection of siRNA against RAR&alpha; (si-RAR&alpha;) or RAR&alpha; was over-expressed by infection of the adenovirus vector pAd-GFP-RAR&alpha; in the VSMCs. The results showed that ATRA significantly induced apelin expression in a time- and dose-dependent manner in the VSMCs. Although RAR&alpha; expression was increased in a time-dependent manner, the expressions of RAR&beta; and RAR&gamma; were little changed by the ATRA treatment. When VSMCs were treated with a RAR&alpha; antagonist Ro 41-5253 prior to the addition of ATRA, or si-RAR&alpha; was used to down regulate endogenous RAR&alpha; expression, the blockade of RAR&alpha; signaling partially reduced the response of apelin to ATRA. Moreover, RAR&alpha; over-expression, induced by infection of pAd-GFP-RAR&alpha;, further increased the induction of apelin by ATRA. In conclusion, ATRA may up-regulate apelin expression in VSMCs, and the mechanism may be RAR&alpha; dependent.
Benzoates ; Chromans ; Gene Expression Regulation ; Intercellular Signaling Peptides and Proteins ; metabolism ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; metabolism ; Real-Time Polymerase Chain Reaction ; Receptors, Retinoic Acid ; metabolism ; Retinoic Acid Receptor alpha ; Signal Transduction ; Transfection ; Tretinoin ; metabolism ; Up-Regulation

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

OBJECTIVETo investigate the effect of all-trans retinoid acid (ATRA) and granulocyte colony-stimulating factor (G-CSF) on the growth, apoptosis, differentiation and expression of RAR&alpha;2 of myeloma cells.

METHODSMyeloma cell lines OPM2 (RAR&alpha;2 positive) and U266 (RAR&alpha;2 negative) were treated with ATRA in the presence or absence of G-CSF. The cells were divided into 6 groups: control groups, G-CSF groups (treated with 1000 U/ml and 2000 U/ml), ATRA groups (treated with 1.0 μmol/L ATRA) and combined groups (treated with 1000 U/mL or 2000 U/mL G-CSF plus 1.0 μmol/L ATRA). The cell viability, growth and apoptosis were examined by MTT method, inverted microscopy and Annexin-V/PI staining, respectively; RAR&alpha;2 expression was detected by reverse transcription PCR; morphology change was evaluated by Wright-Giemsa staining; CD49e expression were analyzed by flow cytometry.

RESULTSThe proliferation of OPM2 cells was inhibited by ATRA treatment (P<0.05) . The growth inhibition rates in combined groups were higher than corresponding single ATRA groups (P<0.05). However, the above effects in U266 cells were not significant (P >0.05). The OPM2 cell stained by Wright-Giemsa in ATRA groups showed that the cell nucleus became smaller, chromatin condensed, number of nucleolus reduced, the volume of cytoplasm increased and the cytoplasm became dark blue. Expression rates of CD49e were low in both U266 and OPM2 cells. Expression of RAR&alpha;2 in OPM2 cells of combination groups were higher than those of control group and corresponding single groups (P<0.05); and there was no significant difference between control group and G-CSF groups (P>0.05). Expression of RAR&alpha;2 in U266 cells of control group and G-CSF groups was not detected; and ATRA groups and combination groups had weak expression.

CONCLUSIONATRA can induce proliferation inhibition in RAR&alpha;2-expressing myeloma cells, and it may also play a certain role in promoting differentiation of RAR&alpha;2 positive myeloma cells.

Cell Differentiation ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Granulocyte Colony-Stimulating Factor ; pharmacology ; Humans ; Multiple Myeloma ; metabolism ; pathology ; Receptors, Retinoic Acid ; metabolism ; Retinoic Acid Receptor alpha ; Tretinoin ; pharmacology

Biomarkers, Tumor ; analysis ; Fatty Acid-Binding Proteins ; analysis ; Humans ; Receptors, Retinoic Acid ; analysis ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ; Two-Dimensional Difference Gel Electrophoresis ; methods ; Up-Regulation ; Urinary Bladder Neoplasms ; chemistry