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1.
PLoS One ; 15(2): e0224644, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32101552

RESUMO

Polybrominated diphenyl ethers (PBDEs) were formally used as flame-retardants and are chemically stable, lipophlic persistent organic pollutants which are known to bioaccumulate in humans. Although its toxicities are well characterized, little is known about the changes in transcriptional regulation caused by PBDE exposure. Long non-coding RNAs (lncRNAs) are increasingly recognized as key regulators of transcriptional and translational processes. It is hypothesized that lncRNAs can regulate nearby protein-coding genes (PCGs) and changes in the transcription of lncRNAs may act in cis to perturb gene expression of its neighboring PCGs. The goals of this study were to 1) characterize PCGs and lncRNAs that are differentially regulated from exposure to PBDEs; 2) identify PCG-lncRNA pairs through genome annotation and predictive binding tools; and 3) determine enriched canonical pathways caused by differentially expressed lncRNA-PCGs pairs. HepaRG cells, which are human-derived hepatic cells that accurately represent gene expression profiles of human liver tissue, were exposed to BDE-47 and BDE-99 at a dose of 25 µM for 24 hours. Differentially expressed lncRNA-PCG pairs were identified through DESeq2 and HOMER; significant canonical pathways were determined through Ingenuity Pathway Analysis (IPA). LncTar was used to predict the binding of 19 lncRNA-PCG pairs with known roles in drug-processing pathways. Genome annotation revealed that the majority of the differentially expressed lncRNAs map to PCG introns. PBDEs regulated overlapping pathways with PXR and CAR such as protein ubiqutination pathway and peroxisome proliferator-activated receptor alpha-retinoid X receptor alpha (PPARα-RXRα) activation but also regulate distinctive pathways involved in intermediary metabolism. PBDEs uniquely down-regulated GDP-L-fucose biosynthesis, suggesting its role in modifying important pathways involved in intermediary metabolism such as carbohydrate and lipid metabolism. In conclusion, we provide strong evidence that PBDEs regulate both PCGs and lncRNAs in a PXR/CAR ligand-dependent and independent manner.


Assuntos
Retardadores de Chama/farmacologia , Perfilação da Expressão Gênica/métodos , Éteres Difenil Halogenados/farmacologia , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , RNA Longo não Codificante/metabolismo , Metabolismo dos Carboidratos , Linhagem Celular , Retardadores de Chama/administração & dosagem , Regulação da Expressão Gênica , Éteres Difenil Halogenados/administração & dosagem , Humanos , Íntrons/genética , Metabolismo dos Lipídeos , PPAR alfa/metabolismo , Receptor de Pregnano X/genética , Receptor de Pregnano X/metabolismo , Receptores Citoplasmáticos e Nucleares/genética , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptor X Retinoide alfa/metabolismo
2.
Toxicol Lett ; 322: 39-49, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31927052

RESUMO

Exposure to the environmental pollutants organotins is of toxicological concern for the marine ecosystem and sensitive human populations, including pregnant women and their unborn children. Using a placenta cell model, we investigated whether organotins at nanomolar concentrations affect the expression and activity of 11ß-hydroxysteroid dehydrogenase type 2 (11ß-HSD2). 11ß-HSD2 represents a placental barrier controlling access of maternal glucocorticoids to the fetus. The organotins tributyltin (TBT) and triphenyltin (TPT) induced 11ß-HSD2 expression and activity in JEG-3 placenta cells, an effect confirmed at the mRNA level in primary human trophoblast cells. Inhibition/knock-down of retinoid X receptor alpha (RXRα) in JEG-3 cells reduced the effect of organotins on 11ß-HSD2 activity, mRNA and protein levels, revealing involvement of RXRα. Experiments using RNA and protein synthesis inhibitors indicated that the effect of organotins on 11ß-HSD2 expression was direct and caused by increased transcription. Induction of placental 11ß-HSD2 activity by TBT, TPT and other endocrine disrupting chemicals acting as RXRα agonists may affect placental barrier function by altering the expression of glucocorticoid-dependent genes and resulting in decreased availability of active glucocorticoids for the fetus, disturbing development and increasing the risk for metabolic and cardiovascular complications in later life.


Assuntos
11-beta-Hidroxiesteroide Desidrogenase Tipo 2/metabolismo , Disruptores Endócrinos/toxicidade , Expressão Gênica/efeitos dos fármacos , Compostos Orgânicos de Estanho/toxicidade , Receptor X Retinoide alfa/metabolismo , Compostos de Trialquitina/toxicidade , 11-beta-Hidroxiesteroide Desidrogenase Tipo 2/genética , Linhagem Celular Tumoral , Feminino , Técnicas de Silenciamento de Genes , Humanos , Placenta/efeitos dos fármacos , Placenta/metabolismo , Gravidez , Receptor X Retinoide alfa/genética , Transfecção , Regulação para Cima
3.
Phytochemistry ; 170: 112216, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31841782

RESUMO

Hyperelodiones A-C, three undescribed monoterpenoid polyprenylated acylphloroglucinols possessing 6/6/6 fused tricyclic core, were isolated from Hypericum elodeoides Choisy. Their gross structures were elucidated by HRESIMS and NMR data. The absolute configurations of hyperelodiones A-C were assigned by their calculated and compared electronic circular dichroism (ECD) spectra combined with their common biosynthetic origin. A fluorescence quenching assay suggested that hyperelodiones A-C could bind to RXRα-LBD, whereas hyperelodione C showed the strongest interaction with a KD of 12.81 µΜ. In addition, hyperelodiones A-C dose-dependently inhibited RXRα transactivation and the growth of HeLa and MCF-7 cells. Among them, hyperelodione C showed the most potent inhibitory activities and dose-dependent PARP cleavage. Molecular docking results suggested that hyperelodione C showed a different interaction mode compared with hyperelodione A and hyperelodione B. Thus, hyperelodione C can be considered as a promising lead compound for cancer therapy, which can bind to RXRα-LBD and induce HeLa and MCF-7 cell apoptosis.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Hypericum/química , Monoterpenos/farmacologia , Compostos Fitoquímicos/farmacologia , Receptor X Retinoide alfa/antagonistas & inibidores , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Células HeLa , Humanos , Células MCF-7 , Conformação Molecular , Simulação de Acoplamento Molecular , Monoterpenos/química , Monoterpenos/isolamento & purificação , Compostos Fitoquímicos/química , Compostos Fitoquímicos/isolamento & purificação , Receptor X Retinoide alfa/metabolismo , Relação Estrutura-Atividade , Células Tumorais Cultivadas
4.
Biomed Res ; 40(5): 189-196, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31597904

RESUMO

Sphingomyelin is a major lipid of the plasma membrane and is enriched in microdomains of the plasma membrane that are critical for signal transduction. However, the function of sphingomyelin in the cell membrane of osteoblasts has not been clarified. Therefore, we examined how sphingomyelin synthase 2 (SMS2) affects osteoclast differentiation by osteoblasts. We knocked down the expression of SMS2 with siRNA targeting the Sgms2 gene in mouse primary osteoblasts. The effects of SMS2 knockdown in osteoblasts were examined using polymerase chain reaction and western blotting. The knockdown of SMS2 suppressed the formation of TRAP-positive multinucleated cells by co-culture of osteoblasts and bone marrow cells compared to the control. We found that receptor activator of nuclear factor κB ligand (RANKL) mRNA expression was significantly reduced by 1,25(OH)2D3 stimulation in SMS2 siRNA osteoblasts. The knockdown of SMS2 repressed the expression of retinoid-X-receptor-α (RXRα) regardless of 1,25(OH)2D3 stimulation. TRAP-positive multinucleated cell formation was significantly reduced by RXRα siRNA in osteoblasts in a co-culture system. These results suggest that SMS2 regulates osteoclast differentiation by inducing RANKL expression via RXRα.


Assuntos
Regulação da Expressão Gênica , Osteoblastos/metabolismo , Osteogênese/genética , Ligante RANK/genética , Transferases (Outros Grupos de Fosfato Substituídos)/genética , Animais , Diferenciação Celular/genética , Células Cultivadas , Técnicas de Silenciamento de Genes , Inativação Gênica , Camundongos , Osteoclastos/metabolismo , Interferência de RNA , RNA Interferente Pequeno/genética , Receptor X Retinoide alfa/genética , Receptor X Retinoide alfa/metabolismo
5.
Mol Med Rep ; 20(4): 3829-3839, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31485615

RESUMO

Peritoneal fibrosis is a serious complication that can occur during peritoneal dialysis (PD), which is primarily caused by damage to peritoneal mesothelial cells (PMCs). The onset of peritoneal fibrosis is delayed or inhibited by promoting PMC survival and inhibiting PMC epithelial­to­mesenchymal transition (EMT). In the present study, the effect of astragaloside IV and the role of the nuclear receptor retinoid X receptor­α (RXRα) in PMCs in high glucose­based PD fluids was investigated. Human PMC HMrSV5 cells were transfected with RXRα short hairpin RNA (shRNA), or an empty vector, and then treated with PD fluids and astragaloside IV. Cell viability, apoptosis and EMT were examined using the Cell Counting Kit­8 assay and flow cytometry, and by determining the levels of caspase­3, E­cadherin and α­smooth muscle actin (α­SMA) via western blot analysis. Cell viability and apoptosis were increased, as were the levels of E­cadherin in HMrSV5 cells following treatment with PD fluid. The protein levels of α­SMA and caspase­3 were increased by treatment with PD fluid. Exposure to astragaloside IV inhibited these changes; however, astragaloside IV did not change cell viability, apoptosis, E­cadherin or α­SMA levels in HMrSV5 cells under normal conditions. Transfection of HMrSV5 cells with RXRα shRNA resulted in decreased viability and E­cadherin expression, and increased apoptosis and α­SMA levels, in HMrSV5 cells treated with PD fluids and co­treated with astragaloside IV or vehicle. These results suggested that astragaloside IV increased cell viability, and inhibited apoptosis and EMT in PMCs in PD fluids, but did not affect these properties of PMCs under normal condition. Thus, the present study suggested that RXRα is involved in maintaining viability, inhibiting apoptosis and reducing EMT of PMCs in PD fluid.


Assuntos
Soluções para Diálise/farmacologia , Diálise Peritoneal , Peritônio/efeitos dos fármacos , Receptor X Retinoide alfa/metabolismo , Saponinas/farmacologia , Triterpenos/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Células Epiteliais/citologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Glucose/metabolismo , Humanos , Diálise Peritoneal/efeitos adversos , Diálise Peritoneal/métodos , Peritônio/citologia , Peritônio/metabolismo
6.
Food Funct ; 10(4): 1974-1984, 2019 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-30889234

RESUMO

Hepatic stellate cells are liver-specific perivascular cells, identified as the major source of collagen in liver fibrosis, following their activation and conversion to myofibroblast-like cells. Lycopene is a carotenoid with biological activities and protective effects described in different pathologies, but little is known about its role in liver protection. We evaluated the influence of lycopene on the cell cycle and lipid metabolism and monitored the possible pathways involved in lycopene inhibition of stellate cell activation. Lycopene induced expression of the lipocyte phenotype, with an accumulation of fat droplets in cytoplasm, with high synthesis and turnover of phospholipids and triglycerides. Cell proliferation analysis showed that lycopene reduced the growth of GRX cells. Lycopene induced an arrest in the G0/G1 phase, followed by a decrease of cells in the G2/M phase, regardless of the concentration of lycopene used. Lycopene modulated relevant signaling pathways related to cholesterol metabolism, cellular proliferation, and lipid metabolism. Also, lycopene treatment increased the expression of RXR-α, RXR-ß, and PPARγ, important biomarkers of liver regeneration. These results show that lycopene was able to negatively modulate events related to the activation of hepatic stellate cells through mechanisms that involve changes in expression of cellular lipid metabolism factors, and suggest that this compound might provide a novel pharmacological approach for the prevention and treatment of fibrotic liver diseases.


Assuntos
Células Estreladas do Fígado/efeitos dos fármacos , Metabolismo dos Lipídeos/efeitos dos fármacos , Licopeno/farmacologia , Ciclo Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Células Estreladas do Fígado/metabolismo , Humanos , Gotículas Lipídicas/metabolismo , Fígado/citologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , PPAR gama/genética , PPAR gama/metabolismo , Receptor X Retinoide alfa/genética , Receptor X Retinoide alfa/metabolismo , Receptor X Retinoide beta/genética , Receptor X Retinoide beta/metabolismo , Transdução de Sinais/efeitos dos fármacos , Triglicerídeos/metabolismo
7.
Mar Drugs ; 17(3)2019 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-30893778

RESUMO

Five new ergostanes, penicisteroids D-H (1-5), were isolated from the liquid culture of the deep-sea-derived fungus Penicillium granulatum MCCC 3A00475, along with 27 known compounds. The structures of the new steroids were established mainly on the basis of extensive analysis of 1D and 2D NMR as well as HRESIMS data. Moreover, the absolute configurations of 1 were confirmed unambiguously by the single-crystal X-ray crystallography. Compounds 2 and 4⁻7 showed moderate antiproliferative effects selectively against 12 different cancer cell lines with IC50 values of around 5 µM. Compounds 2 and 6, potent RXRα binders with Kd values of 13.8 and 12.9 µM, respectively, could induce apoptosis by a Retinoid X Receptor (RXR)-α-dependent mechanism by regulating RXRα transcriptional expression and promoting the poly-ADP-ribose polymerase (PARP) cleavage. Moreover, they could inhibit proliferation by cell cycle arrest at the G0/G1 phase.


Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Organismos Aquáticos/química , Ergosterol/farmacologia , Penicillium/química , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Ergosterol/análogos & derivados , Ergosterol/química , Ergosterol/isolamento & purificação , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Sedimentos Geológicos/microbiologia , Humanos , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Receptor X Retinoide alfa/metabolismo , Transdução de Sinais/efeitos dos fármacos
8.
Acta Crystallogr F Struct Biol Commun ; 75(Pt 2): 98-104, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30713160

RESUMO

The retinoic X receptor (RXR) plays a crucial role in the superfamily of nuclear receptors (NRs) by acting as an obligatory partner of several nuclear receptors; its role as a transcription factor is thus critical in many signalling pathways, such as metabolism, cell development, differentiation and cellular death. The first published structure of the apo ligand-binding domain (LBD) of RXRα, which is still used as a reference today, contained inaccuracies. In the present work, these inaccuracies were corrected using modern crystallographic tools. The most important correction concerns the presence of a π-bulge in helix H7, which was originally built as a regular α-helix. The presence of several CHAPS molecules, which are visible for the first time in the electron-density map and which stabilize the H1-H3 loop, which contains helix H2, are also revealed. The apo RXR structure has played an essential role in deciphering the molecular mode of action of NR ligands and is still used in numerous biophysical studies. This refined structure should be used preferentially in the future in interpreting experiments as well as for modelling and structural dynamics studies of the apo RXRα LBD.


Assuntos
Apoproteínas/química , Apoproteínas/metabolismo , Receptor X Retinoide alfa/química , Receptor X Retinoide alfa/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Cristalização , Cristalografia por Raios X , Humanos , Ligantes , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Domínios Proteicos
9.
Bioorg Chem ; 85: 413-419, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30665035

RESUMO

Retinoid X receptor alpha (RXRα), a central member of the nuclear receptor superfamily and a key regulator of many signal transduction pathways, has been an attractive drug target. We previously discovered that an N-terminally truncated form of RXRα can be induced by specific ligands to form homotetramers, which, as a result of conformational selection, forms the basis for inhibiting the nongenomic activation of RXRα. Here, we report the identification and characterization of atorvastatin as a new RXRα tetramer stabilizer by using structure-based virtual screening and demonstrate that virtual library screening can be used to aid in identifying RXRα ligands that can induce its tetramerization. In this study, docking was applied to screen the FDA-approved small molecule drugs in the DrugBank 4.0 collection. Two compounds were selected and purchased for testing. We showed that the selected atorvastatin could bind to RXRα to promote RXRα-LBD tetramerization. We also showed that atorvastatin possessed RXRα-dependent apoptotic effects. In addition, we used a chemical approach to aid in the studies of the binding mode of atorvastatin.


Assuntos
Atorvastatina/farmacologia , Multimerização Proteica/efeitos dos fármacos , Receptor X Retinoide alfa/metabolismo , Antineoplásicos/química , Antineoplásicos/metabolismo , Antineoplásicos/farmacologia , Atorvastatina/química , Atorvastatina/metabolismo , Sítios de Ligação , Avaliação Pré-Clínica de Medicamentos , Humanos , Ligantes , Células MCF-7 , Ligação Proteica/efeitos dos fármacos , Domínios Proteicos , Estabilidade Proteica/efeitos dos fármacos , Sulindaco/análogos & derivados , Sulindaco/metabolismo
10.
Nat Commun ; 10(1): 253, 2019 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-30651555

RESUMO

The upregulation of PPARγ/RXRα transcriptional activity has emerged as a key event in luminal bladder tumors. It renders tumor cell growth PPARγ-dependent and modulates the tumor microenvironment to favor escape from immuno-surveillance. The activation of the pathway has been linked to PPARG gains/amplifications resulting in PPARγ overexpression and to recurrent activating point mutations of RXRα. Here, we report recurrent mutations of PPARγ that also activate the PPARγ/RXRα pathway, conferring PPARγ-dependency and supporting a crucial role of PPARγ in luminal bladder cancer. These mutations are found throughout the protein-including N-terminal, DNA-binding and ligand-binding domains-and most of them enhance protein activity. Structure-function studies of PPARγ variants with mutations in the ligand-binding domain allow identifying structural elements that underpin their gain-of-function. Our study reveals genomic alterations of PPARG that lead to pro-tumorigenic PPARγ/RXRα pathway activation in luminal bladder tumors and may open the way towards alternative options for treatment.


Assuntos
PPAR gama/genética , Receptor X Retinoide alfa/genética , Transdução de Sinais/genética , Neoplasias da Bexiga Urinária/genética , Linhagem Celular Tumoral , Estudos de Coortes , Cristalografia por Raios X , Feminino , Mutação com Ganho de Função , Células HEK293 , Humanos , Masculino , Simulação de Dinâmica Molecular , PPAR gama/química , PPAR gama/metabolismo , Domínios e Motivos de Interação entre Proteínas/genética , Receptor X Retinoide alfa/metabolismo , Análise de Sequência de DNA , Relação Estrutura-Atividade , Bexiga Urinária/patologia , Neoplasias da Bexiga Urinária/patologia
11.
Biochim Biophys Acta Mol Cell Res ; 1866(3): 317-328, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30529222

RESUMO

Retinoic acid (RA) promotes differentiation in multiple neurogenic cell types by promoting gene reprogramming through retinoid receptors and also by inducing cytosolic signaling events. The nuclear RXR receptors are one of the main mediators of RA cellular effects, classically by joining the direct receptors of RA, the nuclear RAR receptors, in RAR/RXR dimers which act as transcription factors. Distinct RXR genes lead to RXRα, RXRß and RXRγ subtypes, but their specific roles in neuronal differentiation remain unclear. We firstly investigated both RXRs and RARs expression profiles during RA-mediated neuronal differentiation of human neuroblastoma cell line SH-SY5Y, and found varying levels of retinoid receptors transcript and protein contents along the process. In order to understand the roles of the expression of distinct RXR subtypes to RA signal transduction, we performed siRNA-mediated silencing of RXRα and RXRß during the first stages of SH-SY5Y differentiation. Our results showed that RXRα is required for RA-induced neuronal differentiation of SH-SY5Y cells, since its silencing compromised cell cycle arrest and prevented the upregulation of neuronal markers and the adoption of neuronal morphology. Besides, silencing of RXRα affected the phosphorylation of ERK1/2. By contrast, silencing of RXRß improved neurite extension and led to increased expression of tau and synaptophysin, suggesting that RXRß may negatively regulate neuronal parameters related to neurite outgrowth and function. Our results indicate distinct functions for RXR subtypes during RA-dependent neuronal differentiation and reveal new perspectives for studying such receptors as clinical targets in therapies aiming at restoring neuronal function.


Assuntos
Neuritos/metabolismo , Receptor X Retinoide alfa/fisiologia , Receptor X Retinoide beta/fisiologia , Animais , Pontos de Checagem do Ciclo Celular/fisiologia , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Proliferação de Células/efeitos dos fármacos , Neurônios Dopaminérgicos/fisiologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Sistema de Sinalização das MAP Quinases/fisiologia , Neuroblastoma/genética , Neuroblastoma/metabolismo , Ratos , Receptores Citoplasmáticos e Nucleares/genética , Receptores do Ácido Retinoico/metabolismo , Receptores do Ácido Retinoico/fisiologia , Receptor X Retinoide alfa/metabolismo , Receptor X Retinoide beta/metabolismo , Receptores X Retinoide , Transdução de Sinais/efeitos dos fármacos , Ativação Transcricional , Tretinoína/metabolismo , Tretinoína/farmacologia , Células Tumorais Cultivadas
12.
Free Radic Biol Med ; 131: 376-381, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30578920

RESUMO

Chronic kidney disease (CKD) is a worldwide public health problem with an estimated prevalence of 8.2%. This study reports glutathione deficiency, excess oxidative stress, and altered vitamin D metabolism in the kidney of mice fed a high-fat diet (HFD). The levels of GCLC and GCLM gene expression were significantly downregulated and the protein carbonylation level, a hallmark of oxidative damage, was significantly increased in the kidney of HFD-fed mice. While the levels of VD-regulatory genes 1-alpha-hydroxylase (CYP27B1), VDR, and RXRα were significantly downregulated in the kidney of mice fed a HFD, those of 24-hydroxylase (CYP24A1) were significantly elevated. In vitro, GSH deficiency per se causes excess oxidative damage (protein carbonylation), and significantly decreases the levels of VD-regulatory genes (CYP27B1, VDR, and RXRα), but increases levels of CYP24A1 in human renal proximal tubule epithelial cells (RPTEC), similar to findings in the kidney of HFD-fed diabetic mice. L-cysteine supplementation restores GSH and prevents oxidative damage in RPTEC. These studies suggest a potential role of GSH precursor in reducing excess oxidative stress and renal injury that commonly accompanies obesity/diabetes.


Assuntos
25-Hidroxivitamina D3 1-alfa-Hidroxilase/genética , Diabetes Mellitus Experimental/enzimologia , Glutationa/deficiência , Receptores de Calcitriol/genética , Insuficiência Renal Crônica/enzimologia , Vitamina D3 24-Hidroxilase/genética , 25-Hidroxivitamina D3 1-alfa-Hidroxilase/metabolismo , Animais , Cisteína/farmacologia , Diabetes Mellitus Experimental/etiologia , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/patologia , Dieta Hiperlipídica/efeitos adversos , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Regulação da Expressão Gênica , Glutamato-Cisteína Ligase/genética , Glutamato-Cisteína Ligase/metabolismo , Humanos , Túbulos Renais Proximais/metabolismo , Túbulos Renais Proximais/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Estresse Oxidativo , Cultura Primária de Células , Carbonilação Proteica , Receptores de Calcitriol/metabolismo , Insuficiência Renal Crônica/etiologia , Insuficiência Renal Crônica/genética , Insuficiência Renal Crônica/patologia , Receptor X Retinoide alfa/genética , Receptor X Retinoide alfa/metabolismo , Transdução de Sinais , Vitamina D3 24-Hidroxilase/metabolismo
13.
FEBS Lett ; 593(2): 242-250, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30565665

RESUMO

1-[(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalen-2-yl)amino]benzotriazole-5-carboxylic acid (CBt-PMN), a partial agonist of retinoid X receptor (RXR), has attracted attention due to its potential to treat type 2 diabetes and central nervous system diseases with reduced adverse effects of existing full agonists. Herein, we report the crystal structure of CBt-PMN-bound ligand-binding domain of human RXRα (hRXRα) and its biochemical characterization. Interestingly, the structure is a tetramer in nature, in which CBt-PMNs are clearly found binding in two different conformations. The dynamics of the hRXRα/CBt-PMN complex examined using molecular dynamics simulations suggest that the flexibility of the AF-2 interface depends on the conformation of the ligand. These facts reveal that the dual conformation of CBt-PMN in the complex is probably the reason behind its partial agonistic activity.


Assuntos
Receptor X Retinoide alfa/química , Receptor X Retinoide alfa/metabolismo , Tetra-Hidronaftalenos/química , Tetra-Hidronaftalenos/farmacologia , Triazóis/química , Triazóis/farmacologia , Sítios de Ligação , Cristalografia por Raios X , Humanos , Ligantes , Modelos Moleculares , Conformação Molecular , Simulação de Dinâmica Molecular , Ligação Proteica
14.
Mol Pharm ; 16(2): 480-488, 2019 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-29995422

RESUMO

Bexarotene, an agonist of retinoid X receptor alpha (RXRα), has been shown to increase the expression of apoE, ABCA1, and ABCG1 by activating RXR/LXR and RXR/PPAR heterodimers, resulting in amyloid ß (Aß)-protein clearance in the brain of an Alzheimer's disease (AD) mouse model and reversal of mouse cognitive deficits. Nitrostyrene derivative Z-10 is the first identified nitro-ligand of RXRα. We hypothesized that Z-10 and its derivatives have the similar effect as bexarotene. A series of Z-10 derivatives were synthesized by introducing methoxyl, hydroxyl, and methoxy groups in 2- or 4-position of naphthalene ring, respectively. Our reporter gene assays showed that the derivatives with substituted groups of methyl and methoxyl in position 2 were more potent to activate Gal4-DBD/RXRα-LBD and RXRα homodimer as well as RXRα heterodimers than the corresponding 4-substituted derivatives. The derivatives with hydroxyl substitution in either 2- or 4-position failed to activate RXRα. Consistently, the derivatives with stronger potency of RXRα activation had higher RXRα binding affinity. Z-10 and its 2-ethyoxyl substituted derivative Z-36 reduced Aß plaques in both hippocampus and cortex of AD mouse model significantly, of which Z-36 had stronger efficacy. This may due to the stronger ability of Z-36 than Z-10 in activating RXR/LXR and RXR/PPAR heterodimers and inducing ABCA1 and ABCG1 expressions. Thus, the 2- rather than 4-position was the better site for Z-10 modification as to RXRα transactivation, and Z-36 is an optimized derivative of Z-10 as to reducing Aß plaques in AD mouse model.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Naftalenos/uso terapêutico , Nitrocompostos/uso terapêutico , Placa Amiloide/tratamento farmacológico , Receptor X Retinoide alfa/metabolismo , Doença de Alzheimer/metabolismo , Animais , Western Blotting , Modelos Animais de Doenças , Feminino , Masculino , Camundongos , Naftalenos/química , Nitrocompostos/química , Placa Amiloide/metabolismo
15.
Cell Death Dis ; 9(12): 1167, 2018 12 05.
Artigo em Inglês | MEDLINE | ID: mdl-30518934

RESUMO

ABSTACT: Conventional therapies and novel molecular targeted therapies against breast cancer have gained great advances over the past two decades. However, poor prognosis and low survival rate are far from expectation for improvement, particularly in patients with triple negative breast cancer (TNBC). Here, we found that lncRNA DANCR was significantly overregulated in TNBC tissues and cell lines compared with normal breast tissues or other type of breast cancer. Knockdown of DANCR suppressed TNBC proliferation both in vitro and in vivo. Further study of underlying mechanisms demonstrated that DANCR bound with RXRA and increased its serine 49/78 phosphorylation via GSK3ß, resulting in activating PIK3CA transcription, and subsequently enhanced PI3K/AKT signaling and TNBC tumorigenesis. Taken together, Our findings identified DANCR as an pro-oncogene and uncoverd a new working pattern of lncRNA to mediate TNBC tumorigenesis, which may be a potential therapeutic target for improving treatment of TNBC.


Assuntos
Classe I de Fosfatidilinositol 3-Quinases/genética , Regulação Neoplásica da Expressão Gênica , Proteínas Proto-Oncogênicas c-akt/genética , RNA Longo não Codificante/genética , Receptor X Retinoide alfa/genética , Neoplasias de Mama Triplo Negativas/genética , Animais , Carcinogênese/genética , Carcinogênese/metabolismo , Carcinogênese/patologia , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Classe I de Fosfatidilinositol 3-Quinases/metabolismo , Feminino , Glicogênio Sintase Quinase 3 beta/genética , Glicogênio Sintase Quinase 3 beta/metabolismo , Humanos , Camundongos , Camundongos Nus , Fosforilação , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Longo não Codificante/antagonistas & inibidores , RNA Longo não Codificante/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Receptor X Retinoide alfa/metabolismo , Transdução de Sinais , Análise de Sobrevida , Neoplasias de Mama Triplo Negativas/metabolismo , Neoplasias de Mama Triplo Negativas/mortalidade , Neoplasias de Mama Triplo Negativas/patologia , Ensaios Antitumorais Modelo de Xenoenxerto
16.
J Biol Chem ; 293(47): 18180-18191, 2018 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-30275017

RESUMO

Nuclear receptor farnesoid X receptor (FXR) functions as the major bile acid sensor coordinating cholesterol metabolism, lipid homeostasis, and absorption of dietary fats and vitamins. Because of its central role in metabolism, FXR represents an important drug target to manage metabolic and other diseases, such as primary biliary cirrhosis and nonalcoholic steatohepatitis. FXR and nuclear receptor retinoid X receptor α (RXRα) form a heterodimer that controls the expression of numerous downstream genes. To date, the structural basis and functional consequences of the FXR/RXR heterodimer interaction have remained unclear. Herein, we present the crystal structures of the heterodimeric complex formed between the ligand-binding domains of human FXR and RXRα. We show that both FXR and RXR bind to the transcriptional coregulator steroid receptor coactivator 1 with higher affinity when they are part of the heterodimer complex than when they are in their respective monomeric states. Furthermore, structural comparisons of the FXR/RXRα heterodimers and the FXR monomers bound with different ligands indicated that both heterodimerization and ligand binding induce conformational changes in the C terminus of helix 11 in FXR that affect the stability of the coactivator binding surface and the coactivator binding in FXR. In summary, our findings shed light on the allosteric signal transduction in the FXR/RXR heterodimer, which may be utilized for future drug development targeting FXR.


Assuntos
Coativador 1 de Receptor Nuclear/metabolismo , Receptores Citoplasmáticos e Nucleares/química , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptor X Retinoide alfa/química , Receptor X Retinoide alfa/metabolismo , Cristalografia por Raios X , Dimerização , Humanos , Ligantes , Coativador 1 de Receptor Nuclear/química , Coativador 1 de Receptor Nuclear/genética , Ligação Proteica , Domínios Proteicos , Receptores Citoplasmáticos e Nucleares/genética , Receptor X Retinoide alfa/genética
17.
Org Biomol Chem ; 16(38): 7019-7028, 2018 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-30232493

RESUMO

Partial agonists of the transcription factor PPARγ (peroxisome proliferator-activated receptor γ) have shown potential for the treatment of metabolic and inflammatory conditions and novel activators serve as valuable tool and lead compounds. Based on the natural product magnolol (I) and recent structural information of the ligand-target interaction we have previously developed magnolol dimer (II) which has been shown to have enhanced affinity towards PPARγ and improved selectivity over RXRα (retinoid X receptor α), PPARγ's heterodimerization partner. In this contribution we report the synthesis and evaluation of three fragments of the dimeric lead compound by structural simplifications. Sesqui magnolol A and B (III and IV) were found to exhibit comparable activities to magnolol dimer (II) and selectivity over RXRα persisted. Computational studies suggest a common pharmacophore of the distinctive biphenyl motifs. Truncated magnolol dimer (V) on the other hand does not share this feature and was found to act as an antagonist.


Assuntos
Compostos de Bifenilo/química , Compostos de Bifenilo/farmacologia , Lignanas/química , Lignanas/farmacologia , PPAR gama/metabolismo , Compostos de Bifenilo/síntese química , Cristalografia por Raios X , Dimerização , Descoberta de Drogas , Células HEK293 , Humanos , Ligantes , Lignanas/síntese química , Simulação de Acoplamento Molecular , PPAR gama/agonistas , PPAR gama/antagonistas & inibidores , Ligação Proteica , Receptor X Retinoide alfa/metabolismo
18.
Cell Physiol Biochem ; 49(4): 1304-1319, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30223280

RESUMO

BACKGROUND/AIMS: Cholestasis is the major cause of the accumulation of bile acids and results in liver damage, fibrosis, and failure. A growing number of studies have shown that gentiopicroside is a promising prospect that may protect the liver. However, its therapeutic mechanism has not yet been clarified. This study aimed to explore the effect and mechanism of gentiopicroside in cholestasis induced by alpha-naphthylisothiocyanate. METHODS: We performed isobaric tags for relative and absolute quantification-based quantitative proteomics and metabolomics using liquid chromatography quadruple time-of-fight mass spectrometry and identified the expression of 73 metabolites and 84 proteins associated with cholestasis-related dysfunctions in the metabolism of bile acids, fatty acids, and glycerophospholipids. RESULTS: Integrated analyses of proteomic and metabonomic studies showed altered pathways in cholestasis-induced liver injury involving increased activity of farnesoid X receptor/retinoid X receptor, bile acid biosynthesis, and peroxisome proliferator-activated receptor-α/retinoid X receptor-α. Gentiopicroside could reverse these metabolite, protein, and blood biochemical indices, as well as alleviate liver damage. The progressive changes in the proteins and genes may be correlated with cholestasis and were confirmed by western blot and quantitative realtime polymerase chain reaction. CONCLUSION: Gentiopicroside could be used to protect the liver in the presence of cholestasis.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas/patologia , Glucosídeos Iridoides/farmacologia , Metaboloma/efeitos dos fármacos , Metabolômica , Substâncias Protetoras/farmacologia , Proteoma/análise , Proteômica , 1-Naftilisotiocianato/toxicidade , Animais , Ácidos e Sais Biliares/biossíntese , Doença Hepática Induzida por Substâncias e Drogas/tratamento farmacológico , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Colestase/etiologia , Colestase/metabolismo , Análise Discriminante , Regulação da Expressão Gênica/efeitos dos fármacos , Glucosídeos Iridoides/uso terapêutico , Masculino , PPAR alfa/metabolismo , Análise de Componente Principal , Substâncias Protetoras/uso terapêutico , Proteoma/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptor X Retinoide alfa/metabolismo
19.
Aging Cell ; 17(6): e12831, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30216632

RESUMO

Calcium signaling is emerging as a key pathway controlling cellular senescence, a stable cell proliferation arrest playing a fundamental role in pathophysiological conditions, such as embryonic development, wound healing, cancer, and aging. However, how calcium signaling is regulated is still only partially understood. The inositol 1, 4, 5-trisphosphate receptor type 2 (ITPR2), an endoplasmic reticulum calcium release channel, was recently shown to critically contribute to the implementation of senescence, but how ITPR2 expression is controlled is unclear. To gain insights into the regulation of ITPR2 expression, we performed an siRNA screen targeting 160 transcription factors and epigenetic regulators. Interestingly, we discovered that the retinoid X receptor alpha (RXRA), which belongs to the nuclear receptor family, represses ITPR2 expression and regulates calcium signaling though ITPR2 and the mitochondrial calcium uniporter (MCU). Knockdown of RXRA induces the production of reactive oxygen species (ROS) and DNA damage via the ITPR2-MCU calcium signaling axis and consequently triggers cellular senescence by activating p53, whereas RXRA overexpression decreases DNA damage accumulation and then delays replicative senescence. Altogether, our work sheds light on a novel mechanism controlling calcium signaling and cellular senescence and provides new insights into the role of nuclear receptors.


Assuntos
Sinalização do Cálcio , Senescência Celular , Receptor X Retinoide alfa/metabolismo , Cálcio/metabolismo , Canais de Cálcio/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Linhagem Celular , Senescência Celular/efeitos dos fármacos , Quelantes/farmacologia , Dano ao DNA , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Humanos , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , RNA Interferente Pequeno/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Proteínas Repressoras/metabolismo , Transcrição Genética/efeitos dos fármacos , Proteína Supressora de Tumor p53/metabolismo
20.
Cell Mol Biol Lett ; 23: 36, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30093910

RESUMO

The nuclear receptor RXRα (retinoid X receptor-α) is a transcription factor that regulates the expression of multiple genes. Its non-genomic function is largely related to its structure, polymeric forms and modification. Previous research revealed that some non-genomic activity of RXRα occurs via formation of heterodimers with Nur77. RXRα-Nur77 heterodimers translocate from the nucleus to the mitochondria in response to certain apoptotic stimuli and this activity correlates with cell apoptosis. More recent studies revealed a significant role for truncated RXRα (tRXRα), which interacts with the p85α subunit of the PI3K/AKT signaling pathway, leading to enhanced activation of AKT and promoting cell growth in vitro and in animals. We recently reported on a series of NSAID sulindac analogs that can bind to tRXRα through a unique binding mechanism. We also identified one analog, K-80003, which can inhibit cancer cell growth by inducing tRXRα to form a tetramer, thus disrupting p85α-tRXRα interaction. This review analyzes the non-genomic effects of RXRα in normal and tumor cells, and discusses the functional differences based on RXRα protein structure (structure source: the RCSB Protein Data Bank).


Assuntos
Receptor X Retinoide alfa/química , Receptor X Retinoide alfa/metabolismo , Animais , Sítios de Ligação , Bases de Dados de Proteínas , Descoberta de Drogas , Humanos , Modelos Moleculares , Neoplasias/metabolismo , Conformação Proteica , Multimerização Proteica
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