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Sample records for ahr antagonist ch-223191

  1. Genetic and pharmacological analysis identifies a physiological role for the AHR in epidermal differentiation

    PubMed Central

    van den Bogaard, Ellen; Podolsky, Michael; Smits, Jos; Cui, Xiao; John, Christian; Gowda, Krishne; Desai, Dhimant; Amin, Shantu; Schalkwijk, Joost; Perdew, Gary H.

    2015-01-01

    Stimulation of the aryl hydrocarbon receptor (AHR) by xenobiotics is known to affect epidermal differentiation and skin barrier formation. The physiological role of endogenous AHR signaling in keratinocyte differentiation is not known. We used murine and human skin models to address the hypothesis that AHR activation is required for normal keratinocyte differentiation. Using transcriptome analysis of Ahr-/- and Ahr+/+ murine keratinocytes, we found significant enrichment of differentially expressed genes linked to epidermal differentiation. Primary Ahr-/- keratinocytes showed a significant reduction in terminal differentiation gene and protein expression, similar to Ahr+/+ keratinocytes treated with AHR antagonists GNF351 and CH223191, or the selective AHR modulator (SAhRM), SGA360. In vitro keratinocyte differentiation led to increased AHR levels and subsequent nuclear translocation, followed by induced CYP1A1 gene expression. Monolayer cultured primary human keratinocytes treated with AHR antagonists also showed an impaired terminal differentiation program. Inactivation of AHR activity during human skin equivalent development severely impaired epidermal stratification, terminal differentiation protein expression and stratum corneum formation. As disturbed epidermal differentiation is a main feature of many skin diseases, pharmacological agents targeting AHR signaling or future identification of endogenous keratinocyte-derived AHR ligands should be considered as potential new drugs in dermatology. PMID:25602157

  2. TCDD and omeprazole prime platelets through the aryl hydrocarbon receptor (AhR) non-genomic pathway.

    PubMed

    Pombo, Mónica; Lamé, Michael W; Walker, Naomi J; Huynh, Danh H; Tablin, Fern

    2015-05-19

    The role of the aryl hydrocarbon receptor (AhR) in hemostasis has recently gained increased attention. Here, we demonstrate, by qRT-PCR and western blot, that human platelets express both AhR mRNA and AhR protein. AhR protein levels increase in a dose dependent manner when incubated with either 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or omeprazole. Treatment of platelets with puromycin blocks increased AhR protein synthesis in the presence of AhR activators. Additionally, treatment of platelets with either activator results in phosphorylation of p38MAPK and cPLA2, two key signaling molecules in platelet activation pathways. Using the AhR competitive inhibitors alpha naphthoflavone and CH-223191, we show that phosphorylation of p38MAPK is AhR dependent. Further, inhibition of p38MAPK blocks downstream cPLA2 phosphorylation induced by TCDD or omeprazole. Treatment with AhR activators results in platelet priming, as demonstrated by increased platelet aggregation, which is inhibited by AhR antagonists. Our data support a model of the platelet AhR non-genomic pathway in which treatment with AhR activators results in increased expression of the AhR, phosphorylation of p38MAPK and cPLA2, leading to platelet priming in response to agonist. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  3. Crosstalk between AhR and wnt/β-catenin signal pathways in the cardiac developmental toxicity of PM2.5 in zebrafish embryos.

    PubMed

    Zhang, Hang; Yao, Yugang; Chen, Yang; Yue, Cong; Chen, Jiahong; Tong, Jian; Jiang, Yan; Chen, Tao

    2016-04-29

    Recent studies have shown an association between congenital heart defects and air fine particle matter (PM2.5), but the molecular mechanisms remain elusive. It is well known that a number of organic compounds in PM2.5 can act as AhR agonists, and activation of AhR can antagonize Wnt/β-catenin signaling. Therefore, we hypothesized that PM2.5 could activate AhR and then repress the expression of wnt/β-catenin targeted genes essential for cardiogenesis, resulting in heart defects. To test this hypothesis, we investigated the effects of extractable organic matter (EOM) from PM2.5 on AhR and Wnt/β-catenin signal pathways in zebrafish embryos. We confirmed that EOM could cause malformations in the heart and decreased heart rate in zebrafish embryos at 72hpf, and found that the EOM-induced heart defects were rescued in embryos co-exposed with EOM plus AhR antagonist CH223191 or β-catenin agonist CHIR99021. We further found that EOM had increased the expression levels of AhR targeted genes (Cyp1a1, Cyp1b1 and Ahrra) and reduced the mRNA levels of β-catenin targeted genes (axin2, nkx2.5 and sox9b). The mRNA expression level of Rspo2, a β-catenin upstream gene, was also decreased in embryos exposed to EOM. Supplementation with CH223191 or CHIR99021 attenuated most of the EOM-induced expression changes of genes involved in both AhR and wnt/β-catenin signal pathways. However, the mRNA expression level of AhR inhibitor Ahrrb, which did not change by EOM treatment alone, was increased in embryos co-exposed to EOM plus CH223191 or CHIR99021. We conclude that the activation of AhR by EOM from PM2.5 might repress wnt/β-catenin signaling, leading to heart defects in zebrafish embryos. Furthermore, our results indicate that the cardiac developmental toxicity of PM2.5 might be prevented by targeting AhR or wnt/β-catenin signaling. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  4. The AhR is involved in the regulation of LoVo cell proliferation through cell cycle-associated proteins.

    PubMed

    Yin, Jiuheng; Sheng, Baifa; Han, Bin; Pu, Aimin; Yang, Kunqiu; Li, Ping; Wang, Qimeng; Xiao, Weidong; Yang, Hua

    2016-05-01

    Some ingredients in foods can activate the aryl hydrocarbon receptor (AhR) and arrest cell proliferation. In this study, we hypothesized that 6-formylindolo [3, 2-b] carbazole (FICZ) arrests the cell cycle in LoVo cells (a colon cancer line) through the AhR. The AhR agonist FICZ and the AhR antagonist CH223191 were used to treat LoVo cells. Real-time PCR and Western blot analyses were performed to detect the expression of the AhR, CYP1A1, CDK4, cyclinD1, cyclin E, CDK2, P27, and pRb. The distribution and activation of the AhR were detected with immunofluorescence. A 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometric analysis were performed to measure cell viability, cell cycle stage, and apoptosis. Our results show that FICZ inhibited LoVo cell proliferation by inducing G1 cell cycle arrest but had no effect on epithelial apoptosis. Further analysis found that FICZ downregulated cyclinD1 and upregulated p27 expression to arrest Rb phosphorylation. The downregulation of cyclinD1 and upregulation of p27 were abolished by co-treatment with CH223191. We conclude that the AhR, when activated by FICZ (an endogenous AhR ligand), can arrest the cell cycle and block LoVo cell proliferation. © 2016 International Federation for Cell Biology.

  5. Inhibition of the aryl hydrocarbon receptor prevents Western diet-induced obesity. Model for AHR activation by kynurenine via oxidized-LDL, TLR2/4, TGFβ, and IDO1.

    PubMed

    Moyer, Benjamin J; Rojas, Itzel Y; Kerley-Hamilton, Joanna S; Hazlett, Haley F; Nemani, Krishnamurthy V; Trask, Heidi W; West, Rachel J; Lupien, Leslie E; Collins, Alan J; Ringelberg, Carol S; Gimi, Barjor; Kinlaw, William B; Tomlinson, Craig R

    2016-06-01

    Obesity is an increasingly urgent global problem, yet, little is known about its causes and less is known how obesity can be effectively treated. We showed previously that the aryl hydrocarbon receptor (AHR) plays a role in the regulation of body mass in mice fed Western diet. The AHR is a ligand-activated nuclear receptor that regulates genes involved in a number of biological pathways, including xenobiotic metabolism and T cell polarization. This study was an investigation into whether inhibition of the AHR prevents Western diet-based obesity. Male C57Bl/6J mice were fed control and Western diets with and without the AHR antagonist α-naphthoflavone or CH-223191, and a mouse hepatocyte cell line was used to delineate relevant cellular pathways. Studies are presented showing that the AHR antagonists α-naphthoflavone and CH-223191 significantly reduce obesity and adiposity and ameliorates liver steatosis in male C57Bl/6J mice fed a Western diet. Mice deficient in the tryptophan metabolizing enzyme indoleamine 2,3-dioxygenase 1 (IDO1) were also resistant to obesity. Using an AHR-directed, luciferase-expressing mouse hepatocyte cell line, we show that the transforming growth factor β1 (TGFβ1) signaling pathway via PI3K and NF-κB and the toll-like receptor 2/4 (TLR2/4) signaling pathway stimulated by oxidized low-density lipoproteins via NF-κB, each induce luciferase expression; however, TLR2/4 signaling was significantly reduced by inhibition of IDO1. At physiological levels, kynurenine but not kynurenic acid (both tryptophan metabolites and known AHR agonists) activated AHR-directed luciferase expression. We propose a hepatocyte-based model, in which kynurenine production is increased by enhanced IDO1 activity stimulated by TGFβ1 and TLR2/4 signaling, via PI3K and NF-κB, to perpetuate a cycle of AHR activation to cause obesity; and inhibition of the AHR, in turn, blocks the cycle's output to prevent obesity. The AHR with its broad ligand binding specificity

  6. Norisoboldine, a natural AhR agonist, promotes Treg differentiation and attenuates colitis via targeting glycolysis and subsequent NAD+/SIRT1/SUV39H1/H3K9me3 signaling pathway.

    PubMed

    Lv, Qi; Wang, Kai; Qiao, Simiao; Yang, Ling; Xin, Yirong; Dai, Yue; Wei, Zhifeng

    2018-02-15

    Norisoboldine (NOR), a natural aryl hydrocarbon receptor (AhR) agonist, has been demonstrated to attenuate ulcerative colitis (UC) and induce the generation of Treg cells. Under UC condition, hypoxia widely exists in colonic mucosa, and secondary changes of microRNAs (miRs) expressions and glycolysis contribute to Treg differentiation. At present, we worked for exploring the deep mechanisms for NOR-promoted Treg differentiation in hypoxia and its subsequent anti-UC action from the angle of AhR/miR or AhR/glycolysis axis. Results showed that NOR promoted Treg differentiation in hypoxia and the effect was stronger relative to normoxia. It activated AhR in CD4 + T cells under hypoxic microenvironment; CH223191 (a specific AhR antagonist) and siAhR-3 abolished NOR-promoted Treg differentiation. Furthermore, the progress of glycolysis, levels of Glut1 and HK2, and expression of miR-31 rather than miR-219 and miR-490 in CD4 + T cells were downregulated by NOR treatment under hypoxic microenvironment. However, HK2 plasmid but not miR-31 mimic significantly interfered NOR-enhanced Treg polarization. In addition, NOR reduced NAD + and SIRT1 levels, facilitated the ubiquitin-proteasomal degradation of SUV39H1 protein, and inhibited the enrichment of H3K9me3 at -1, 201 to -1,500 region of Foxp3 promoter in CD4 + T cells under hypoxic microenvironment, which was weakened by HK2 plasmid, CH223191, and siAhR-3. Finally, the correlation between NOR-mediated activation of AhR, repression of glycolysis, regulation of NAD + /SIRT1/SUV39H1/H3K9me3 signals, induction of Treg cells, and remission of colitis was confirmed in mice with DSS-induced colitis by using CH223191 and HK2 plasmid. In conclusion, NOR promoted Treg differentiation and then alleviated the development of colitis by regulating AhR/glycolysis axis and subsequent NAD + /SIRT1/SUV39H1/H3K9me3 signaling pathway.

  7. Aryl hydrocarbon receptor (AHR) regulation of L-Type Amino Acid Transporter 1 (LAT-1) expression in MCF-7 and MDA-MB-231 breast cancer cells.

    PubMed

    Tomblin, Justin K; Arthur, Subha; Primerano, Donald A; Chaudhry, Ateeq R; Fan, Jun; Denvir, James; Salisbury, Travis B

    2016-04-15

    The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that is regulated by environmental toxicants that function as AHR agonists such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). L-Type Amino Acid Transporter 1 (LAT1) is a leucine transporter that is overexpressed in cancer. The regulation of LAT1 by AHR in MCF-7 and MDA-MB-231 breast cancer cells (BCCs) was investigated in this report. Ingenuity pathway analysis (IPA) revealed a significant association between TCDD-regulated genes (TRGs) and molecular transport. Overlapping the TCDD-RNA-Seq dataset obtained in this study with a published TCDD-ChIP-seq dataset identified LAT1 as a primary target of AHR-dependent TCDD induction. Short interfering RNA (siRNA)-directed knockdown of AHR confirmed that TCDD-stimulated increases in LAT1 mRNA and protein required AHR expression. TCDD-stimulated increases in LAT1 mRNA were also inhibited by the AHR antagonist CH-223191. Upregulation of LAT1 by TCDD coincided with increases in leucine uptake by MCF-7 cells in response to TCDD. Chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) assays revealed increases in AHR, AHR nuclear translocator (ARNT) and p300 binding and histone H3 acetylation at an AHR binding site in the LAT1 gene in response to TCDD. In MCF-7 and MDA-MB-231 cells, endogenous levels of LAT1 mRNA and protein were reduced in response to knockdown of AHR expression. Knockdown experiments demonstrated that proliferation of MCF-7 and MDA-MB-231 cells is dependent on both LAT1 and AHR. Collectively, these findings confirm the dependence of cancer cells on leucine uptake and establish a mechanism for extrinsic and intrinsic regulation of LAT1 by AHR. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Benzo[ghi]perylene activates the AHR pathway to exert biological effects on the NL-20 human bronchial cell line.

    PubMed

    Zaragoza-Ojeda, Montserrat; Eguía-Aguilar, Pilar; Perezpeña-Díazconti, Mario; Arenas-Huertero, Francisco

    2016-08-10

    Polycyclic aromatic hydrocarbons (PAH) are produced by incomplete combustion of organic material. In the Mexico City atmosphere, the most abundant PAH is benzo[ghi]perylene (BghiP), a gasoline combustion marker. At present, there are no reports of the effects of BghiP on human bronchial cells, so the aim of the study was to evaluate the effects in vitro of BghiP on the NL-20 cell line. Results showed that BghiP induced the formation of small vesicles throughout the cytoplasm, with absence of nuclear fragmentation. At 48h exposition, damage in cell membrane increased significantly at 1.24μg/mL of BghiP (p<0.05). Immunocytochemistry revealed that BghiP provokes nuclear translocation of AhR receptor, which indicates that this compound can induce transcription of genes via receptor binding (AhR pathway activation). BghiP induced a two-fold increase (p<0.05) in the expression of AhR and CYP4B1 (a lung-specific pathway effector). In the presence of the receptor antagonist CH-223191, the loss of viability, the nuclear translocation and the overexpression of genes decreased, though this did not prevent the formation of vesicles. BghiP induced oxidative stress and in presence of the receptor antagonist this increased significantly. In conclusion, BghiP can activate the overexpression of AhR and CYP4B1, and the effects are abated by the AhR receptor antagonist. This is the first report to prove that BghiP utilizes the AhR pathway to exert its toxic effects on the NL-20 human bronchial cell line . Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  9. Inhibition of the aryl hydrocarbon receptor prevents Western diet-induced obesity. Model for AHR activation by kynurenine via oxidized-LDL, TLR2/4, TGFβ, and IDO1

    SciTech Connect

    Moyer, Benjamin J.

    Obesity is an increasingly urgent global problem, yet, little is known about its causes and less is known how obesity can be effectively treated. We showed previously that the aryl hydrocarbon receptor (AHR) plays a role in the regulation of body mass in mice fed Western diet. The AHR is a ligand-activated nuclear receptor that regulates genes involved in a number of biological pathways, including xenobiotic metabolism and T cell polarization. This study was an investigation into whether inhibition of the AHR prevents Western diet-based obesity. Male C57Bl/6J mice were fed control and Western diets with and without the AHRmore » antagonist α-naphthoflavone or CH-223191, and a mouse hepatocyte cell line was used to delineate relevant cellular pathways. Studies are presented showing that the AHR antagonists α-naphthoflavone and CH-223191 significantly reduce obesity and adiposity and ameliorates liver steatosis in male C57Bl/6J mice fed a Western diet. Mice deficient in the tryptophan metabolizing enzyme indoleamine 2,3-dioxygenase 1 (IDO1) were also resistant to obesity. Using an AHR-directed, luciferase-expressing mouse hepatocyte cell line, we show that the transforming growth factor β1 (TGFβ1) signaling pathway via PI3K and NF-κB and the toll-like receptor 2/4 (TLR2/4) signaling pathway stimulated by oxidized low-density lipoproteins via NF-κB, each induce luciferase expression; however, TLR2/4 signaling was significantly reduced by inhibition of IDO1. At physiological levels, kynurenine but not kynurenic acid (both tryptophan metabolites and known AHR agonists) activated AHR-directed luciferase expression. We propose a hepatocyte-based model, in which kynurenine production is increased by enhanced IDO1 activity stimulated by TGFβ1 and TLR2/4 signaling, via PI3K and NF-κB, to perpetuate a cycle of AHR activation to cause obesity; and inhibition of the AHR, in turn, blocks the cycle's output to prevent obesity. The AHR with its broad ligand binding

  10. SLC6A19 is a novel putative gene, induced by dioxins via AhR in human hepatoma HepG2 cells.

    PubMed

    Tian, Wenjing; Fu, Hualing; Xu, Tuan; Xu, Sherry Li; Guo, Zhiling; Tian, Jijing; Tao, Wuqun; Xie, Heidi Qunhui; Zhao, Bin

    2018-06-01

    The aryl hydrocarbon receptor (AhR) plays an important role in mediating dioxins toxicity. Currently, genes of P450 families are major research interests in studies on AhR-mediated gene alterations caused by dioxins. Genes related to other metabolic pathways or processes may be also responsive to dioxin exposures. Amino acid transporter B0AT1 (encoded by SLC6A19) plays a decisive role in neutral amino acid transport which is present in kidney, intestine and liver. However, effects of dioxins on its expression are still unknown. In the present study, we focused on the effects of dioxin and dioxin-like compounds on SLC6A19 expression in HepG2 cells. We identified SLC6A19 as a novel putative target gene of AhR activation in HepG2 cells. 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) increased the expression of SLC6A19 in time- and concentration-dependent manners. Using AhR antagonist CH223191 and/or siRNA assays, we demonstrated that certain AhR agonists upregulated SLC6A19 expression via AhR, including TCDD, 1,2,3,7,8-pentachlorodibenzo-p-dioxin (1,2,3,7,8-PeCDD), 2,3,4,7,8- pentachlorodibenzofuran (2,3,4,7,8-PeCDF) and PCB126. In addition, the expression of B0AT1 was also significantly induced by TCDD in HepG2 cells. Our study suggested that dioxins might affect the transcription and translation of SLC6A19 in HepG2 cells, which might be a novel putative gene to assess dioxins' toxicity in amino acid transport and metabolism in liver. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Novel roles for AhR and ARNT in the regulation of alcohol dehydrogenases in human hepatic cells.

    PubMed

    Attignon, Eléonore A; Leblanc, Alix F; Le-Grand, Béatrice; Duval, Caroline; Aggerbeck, Martine; Rouach, Hélène; Blanc, Etienne B

    2017-01-01

    The mechanisms by which pollutants participate in the development of diverse pathologies are not completely understood. The pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) activates the AhR (aryl hydrocarbon receptor) signaling pathway. We previously showed that TCDD (25 nM, 30 h) decreased the expression of several alcohol metabolism enzymes (cytochrome P450 2E1, alcohol dehydrogenases ADH1, 4 and 6) in differentiated human hepatic cells (HepaRG). Here, we show that, as rapidly as 8 h after treatment (25 nM TCDD) ADH expression decreased 40 % (p < 0.05). ADH1 and 4 protein levels decreased 40 and 27 %, respectively (p < 0.05), after 72 h (25 nM TCDD). The protein half-lives were not modified by TCDD which suggests transcriptional regulation of expression. The AhR antagonist CH-223191 or AhR siRNA reduced the inhibitory effect of 25 nM TCDD on ADH1A, 4 and 6 expression 50-100 % (p < 0.05). The genomic pathway (via the AhR/ARNT complex) and not the non-genomic pathway involving c-SRC mediated these effects. Other AhR ligands (3-methylcholanthrene and PCB 126) decreased ADH1B, 4 and 6 mRNAs by more than 78 and 55 %, respectively (p < 0.01). TCDD also regulated the expression of ADH4 in the HepG2 human hepatic cell line, in primary human hepatocytes and in C57BL/6J mouse liver. In conclusion, activation of the AhR/ARNT signaling pathway by AhR ligands represents a novel mechanism for regulating the expression of ADHs. These effects may be implicated in the toxicity of AhR ligands as well as in the alteration of ethanol or retinol metabolism and may be associated further with higher risk of liver diseases or/and alcohol abuse disorders.

  12. Characterization of AhR agonists reveals antagonistic activity in European herring gull (Larus argentatus) eggs.

    PubMed

    Muusse, Martine; Christensen, Guttorm; Gomes, Tânia; Kočan, Anton; Langford, Katherine; Tollefsen, Knut Erik; Vaňková, Lenka; Thomas, Kevin V

    2015-05-01

    European herring gull (Larus argentatus) eggs from two Norwegian islands, Musvær in the south east and Reiaren in Northern Norway, were screened for dioxins, furans, and dioxin-like and selected non-dioxin-like polychlorinated biphenyls (PCBs), and subjected to non-target analysis to try to identify the aryl hydrocarbon receptor (AhR) agonists, responsible for elevated levels measured using the dioxin responsive chemically activated luciferase expression (DR-CALUX) assay. Eggs from Musvær contained chemically calculated toxic equivalent (WHO TEQ) levels of between 109 and 483 pg TEQ/g lw, and between 82 and 337 pg TEQ/g lw was determined in eggs from Reiaren. In particular PCB126 contributed highly to the total TEQ (69-82%). In 19 of the 23 samples the calculated WHO TEQ was higher than the TEQCALUX. Using CALUX specific relative effect potencies (REPs), the levels were lower at between 77 and 292 pg/g lw in eggs from Musvær and between 55 and 223 pg/g lw in eggs from Reiaren, which was higher than the TEQCALUX in 16 of the 23 samples. However, the means of the REP values and the TEQCALUX were not significantly different. This suggests the presence of compounds that can elicit antagonist effects, with a low binding affinity to the AhR. Non-target analysis identified the presence of hexachlorobenzene (HCB) (quantified at 9.6-185 pg/g lw) but neither this compound nor high concentrations of PCB126 and non-dioxin-like PCBs could explain the differences between the calculated TEQ or REP values and the TEQCALUX. Even though, for most AhR agonists, the sensitivity of herring gulls is not known, the reported levels can be considered to represent a risk for biological effects in the developing embryo, compared to LC50 values in chicken embryos. For human consumers of herring gull eggs, these eggs contain TEQ levels up to four times higher than the maximum tolerable weekly intake. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. The AhR and NF-κB/Rel Proteins Mediate the Inhibitory Effect of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin on the 3′ Immunoglobulin Heavy Chain Regulatory Region

    PubMed Central

    Salisbury, Richard L.; Sulentic, Courtney E. W.

    2015-01-01

    Transcriptional regulation of the murine immunoglobulin (Ig) heavy chain gene (Igh) involves several regulatory elements including the 3′Igh regulatory region (3′IghRR), which is composed of at least 4 enhancers (hs3A, hs1.2, hs3B, and hs4). The hs1.2 and hs4 enhancers exhibit the greatest transcriptional activity and contain binding sites for several transcription factors including nuclear factor kappaB/Rel (NF-κB/Rel) proteins and the aryl hydrocarbon receptor (AhR). Interestingly, the environmental immunosuppressant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which potently inhibits antibody secretion, also profoundly inhibits 3′IghRR and hs1.2 enhancer activation induced by the B-lymphocyte activator lipopolysaccharide (LPS), but enhances LPS-induced activation of the hs4 enhancer. Within the hs1.2 and hs4 enhancers, the AhR binding site is in close proximity or overlaps an NF-κB/Rel binding site suggesting a potential reciprocal modulation of the 3′IghRR by AhR and NF-κB/Rel. The objective of the current study was to evaluate the role of NF-κB/Rel and the AhR on the 3′IghRR and its enhancers using the AhR ligand TCDD, the AhR antagonist CH223191, and toll-like receptor agonists LPS, Resiquimod (R848), or cytosine-phosphate-guanine-oligodeoxynucleotides (CpG). Utilizing the CH12.LX B-lymphocyte cell line and variants expressing either a 3′IghRR-regulated transgene reporter or an inducible IκBα (inhibitor kappa B-alpha protein) superrepressor (IκBαAA), we demonstrate an AhR- and NF-κB/Rel-dependent modulation of 3′IghRR and hs4 activity. Additionally, in mouse splenocytes or CH12.LX cells, binding within the hs1.2 and hs4 enhancer of the AhR and the NF-κB/Rel proteins RelA and RelB was differentially altered by the cotreatment of LPS and TCDD. These results suggest that the AhR and NF-κB/Rel protein binding profile within the 3′IghRR mediates the inhibitory effects of TCDD on Ig expression and therefore antibody levels. PMID:26377645

  14. AHR-16303B, a novel antagonist of 5-HT2 receptors and voltage-sensitive calcium channels

    SciTech Connect

    Barrett, R.J.; Appell, K.C.; Kilpatrick, B.F.

    1991-01-01

    In vivo and in vitro methods were used to characterize AHR-16303B, a novel compound with antagonistic action at 5-HT2 receptors and voltage-sensitive calcium channels. The 5-HT2 receptor-antagonistic properties of AHR-16303B were demonstrated by inhibition of (a) (3H)ketanserin binding to rat cerebral cortical membranes (IC50 = 165 nM); (b) 5-hydroxytryptamine (5-HT)-induced foot edema in rats (minimum effective dose, (MED) = 0.32 mg/kg orally, p.o.); (c) 5-HT-induced vasopressor responses in spontaneously hypertensive rats (SHR) (ID50 = 0.18 mg/kg intravenously (i.v.), 1.8 mg/kg p.o.), (d) 5-HT-induced antidiuresis in rats (MED = 1 mg/kg p.o.), and (e) platelet aggregation induced by 5-HT + ADPmore » (IC50 = 1.5 mM). The calcium antagonist properties of AHR-16303B were demonstrated by inhibition of (a) (3H)nimodipine binding to voltage-sensitive calcium channels on rabbit skeletal muscle membranes (IC50 = 15 nM), (b) KCl-stimulated calcium flux into cultured PC12 cells (IC50 = 81 nM), and (c) CaCl2-induced contractions of rabbit thoracic aortic strips (pA2 = 8.84). AHR-16303B had little or no effect on binding of radioligands to dopamine2 (DA2) alpha 1, alpha 2, H1, 5-HT1 alpha, beta 2, muscarinic M1, or sigma opioid receptors; had no effect on 5-HT3 receptor-mediated vagal bradycardia; and had only minor negative inotropic, chronotropic, and dromotropic effects on isolated guinea pig atria. In conscious SHR, 30 mg/kg p.o. AHR-16303B completely prevented the vasopressor responses to i.v. 5-HT, and decreased blood pressure (BP) by 24% 3 h after dosing.« less

  15. Essential oils of culinary herbs and spices display agonist and antagonist activities at human aryl hydrocarbon receptor AhR.

    PubMed

    Bartoňková, Iveta; Dvořák, Zdeněk

    2018-01-01

    Essential oils (EOs) of culinary herbs and spices are used to flavor, color and preserve foods and drinks. Dietary intake of EOs is significant, deserving an attention of toxicologists. We examined the effects of 31 EOs of culinary herbs and spices on the transcriptional activity of human aryl hydrocarbon receptor (AhR), which is a pivotal xenobiotic sensor, having also multiple roles in human physiology. Tested EOs were sorted out into AhR-inactive ones (14 EOs) and AhR-active ones, including full agonists (cumin, jasmine, vanilla, bay leaf), partial agonists (cloves, dill, thyme, nutmeg, oregano) and antagonists (tarragon, caraway, turmeric, lovage, fennel, spearmint, star anise, anise). Major constituents (>10%) of AhR-active EOs were studied in more detail. We identified AhR partial agonists (carvacrol, ligustilide, eugenol, eugenyl acetate, thymol, ar-turmerone) and antagonists (trans-anethole, butylidine phtalide, R/S-carvones, p-cymene), which account for AhR-mediated activities of EOs of fennel, anise, star anise, caraway, spearmint, tarragon, cloves, dill, turmeric, lovage, thyme and oregano. We also show that AhR-mediated effects of some individual constituents of EOs differ from those manifested in mixtures. In conclusion, EOs of culinary herbs and spices are agonists and antagonists of human AhR, implying a potential for food-drug interactions and interference with endocrine pathways. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Cigarette smoke-induced cell death of a spermatocyte cell line can be prevented by inactivating the Aryl hydrocarbon receptor

    PubMed Central

    Esakky, P; Hansen, D A; Drury, A M; Cusumano, A; Moley, K H

    2015-01-01

    Cigarette smoke exposure causes germ cell death during spermatogenesis. Our earlier studies demonstrated that cigarette smoke condensate (CSC) causes spermatocyte cell death in vivo and growth arrest of the mouse spermatocyte cell line (GC-2spd(ts)) in vitro via the aryl hydrocarbon receptor (AHR). We hypothesize here that inactivation of AHR could prevent the CSC-induced cell death in spermatocytes. We demonstrate that CSC exposure generates oxidative stress, which differentially regulates mitochondrial apoptosis in GC-2spd(ts) and wild type (WT) and AHR knockout (AHR-KO) mouse embryonic fibroblasts (MEFs). SiRNA-mediated silencing of Ahr augments the extent of CSC-mediated cellular damage while complementing the AHR-knockout condition. Pharmacological inhibition using the AHR-antagonist (CH223191) modulates the CSC-altered expression of apoptotic proteins and significantly abrogates DNA fragmentation though the cleavage of PARP appears AHR independent. Pretreatment with CH223191 at concentrations above 50 μM significantly prevents the CSC-induced activation of caspase-3/7 and externalization of phosphatidylserine in the plasma membrane. However, MAPK inhibitors alone or together with CH223191 could not prevent the membrane damage upon CSC addition and the caspase-3/7 activation and membrane damage in AHR-deficient MEF indicates the interplay of multiple cell signaling and cytoprotective ability of AHR. Thus the data obtained on one hand signifies the protective role of AHR in maintaining normal cellular homeostasis and the other, could be a potential prophylactic therapeutic target to promote cell survival and growth under cigarette smoke exposed environment by receptor antagonism via CH223191-like mechanism. Antagonist-mediated inactivation of the aryl hydrocarbon receptor blocks downstream events leading to cigarette smoke-induced cell death of a spermatocyte cell line. PMID:27551479

  17. Adaptive changes in global gene expression profile of lung carcinoma A549 cells acutely exposed to distinct types of AhR ligands.

    PubMed

    Procházková, Jiřina; Strapáčová, Simona; Svržková, Lucie; Andrysík, Zdeněk; Hýžďalová, Martina; Hrubá, Eva; Pěnčíková, Kateřina; Líbalová, Helena; Topinka, Jan; Kléma, Jiří; Espinosa, Joaquín M; Vondráček, Jan; Machala, Miroslav

    2018-08-01

    Exposure to persistent ligands of aryl hydrocarbon receptor (AhR) has been found to cause lung cancer in experimental animals, and lung adenocarcinomas are often associated with enhanced AhR expression and aberrant AhR activation. In order to better understand the action of toxic AhR ligands in lung epithelial cells, we performed global gene expression profiling and analyze TCDD-induced changes in A549 transcriptome, both sensitive and non-sensitive to CH223191 co-treatment. Comparison of our data with results from previously reported microarray and ChIP-seq experiments enabled us to identify candidate genes, which expression status reflects exposure of lung cancer cells to TCDD, and to predict processes, pathways (e.g. ER stress, Wnt/β-cat, IFNɣ, EGFR/Erbb1), putative TFs (e.g. STAT, AP1, E2F1, TCF4), which may be implicated in adaptive response of lung cells to TCDD-induced AhR activation. Importantly, TCDD-like expression fingerprint of selected genes was observed also in A549 cells exposed acutely to both toxic (benzo[a]pyrene, benzo[k]fluoranthene) and endogenous AhR ligands (2-(1H-Indol-3-ylcarbonyl)-4-thiazolecarboxylic acid methyl ester and 6-formylindolo[3,2-b]carbazole). Overall, our results suggest novel cellular candidates, which could help to improve monitoring of AhR-dependent transcriptional activity during acute exposure of lung cells to distinct types of environmental pollutants. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. The Aryl Hydrocarbon Receptor (AhR) as a Drug Target for Cancer Chemotherapy.

    PubMed

    Safe, Stephen; Cheng, Yating; Jin, Un-Ho

    2017-02-01

    The aryl hydrocarbon receptor (AhR) is overexpressed in some patients with different tumor types, and the receptor can be a negative or positive prognostic factor. There is also evidence from both in vivo and in vitro cell culture models that the AhR can exhibit tumor-specific pro-oncogenic and tumor suppressor-like functions and therefore can be treated with AhR antagonists or agonists, respectively. Successful clinical applications of AhR ligands will require the synthesis and development of selective AhR modulators (SAhRMs) with tumor-specific AhR agonist or antagonist activity, and some currently available compounds such as indole-3-carbinol and diindolylmethane-(DIM) and synthetic AhR antagonists are potential drug candidates. There is also evidence that some AhR-active pharmaceuticals, including tranilast, flutamide, hydroxytamoxifen and omeprazole or their derivatives, may be effective AhR-dependent anticancer agents for single or combination cancer chemotherapies for treatment of breast and pancreatic cancers.

  19. The aryl hydrocarbon receptor (AhR) mediates resistance to apoptosis induced in breast cancer cells.

    PubMed

    Bekki, Kanae; Vogel, Helena; Li, Wen; Ito, Tomohiro; Sweeney, Colleen; Haarmann-Stemmann, Thomas; Matsumura, Fumio; Vogel, Christoph F A

    2015-05-01

    The aryl hydrocarbon receptor (AhR) is well known as a ligand binding transcription factor regulating various biological effects. Previously we have shown that long-term exposure to estrogen in breast cancer cells caused not only down regulation of estrogen receptor (ER) but also overexpression of AhR. The AhR interacts with several cell signaling pathways associated with induction of tyrosine kinases, cytokines and growth factors which may support the survival roles of AhR escaping from apoptosis elicited by a variety of apoptosis inducing agents in breast cancer. In this study, we studied the anti-apoptotic role of AhR in different breast cancer cells when apoptosis was induced by exposure to UV light and chemotherapeutic agents. Activation of AhR by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in AhR overexpressing breast cancer cells effectively suppressed the apoptotic response induced by UV-irradiation, doxorubicin, lapatinib and paclitaxel. The anti-apoptotic response of TCDD was uniformly antagonized by the treatment with 3'methoxy-4'nitroflavone (MNF), a specific antagonist of AhR. TCDD's survival action of apoptosis was accompanied with the induction of well-known inflammatory genes, such as cyclooxygenase-2 (COX-2) and NF-κB subunit RelB. Moreover, TCDD increased the activity of the immunosuppressive enzyme indoleamine 2, 3-dioxygenase (IDO), which metabolizes tryptophan to kynurenine (Kyn) and mediates tumor immunity. Kyn also acts as an AhR ligand like TCDD, and kyn induced an anti-apoptotic response in breast cancer cells. Accordingly, our present study suggests that AhR plays a pivotal role in the development of breast cancer via the suppression of apoptosis, and provides an idea that the use of AhR antagonists with chemotherapeutic agents may effectively synergize the elimination of breast cancer cells. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Ahr function in lymphocytes: emerging concepts

    PubMed Central

    Zhou, Liang

    2015-01-01

    The aryl hydrocarbon receptor (Ahr) is an important regulator of the development and function of both innate and adaptive immune cells through roles associated with Ahr's ability to respond to cellular and dietary ligands. Recent findings have revealed tissue and context-specific functions for Ahr in both homeostasis and in during an immune response. I review these findings here, and integrate them into the current understanding of the mechanisms that regulate Ahr transcription and function. I propose a conceptual framework in which Ahr function is determined by three factors: the amount of Ahr in any given cell, the abundance and potency of Ahr ligands within certain tissues, and the tissue microenvironment wherein Ahr+ cells reside. This complexity emphasizes the necessity cell-type specific genetic approaches towards the study of Ahr function. PMID:26700314

  1. Potencies of red seabream AHR1- and AHR2-mediated transactivation by dioxins: implication of both AHRs in dioxin toxicity.

    PubMed

    Bak, Su-Min; Iida, Midori; Hirano, Masashi; Iwata, Hisato; Kim, Eun-Young

    2013-03-19

    To evaluate species- and isoform-specific responses to dioxins and related compounds (DRCs) via aryl hydrocarbon receptor (AHR) in the red seabream ( Pagrus major ), we constructed a reporter gene assay system. Each expression plasmid of red seabream AHR1 (rsAHR1) and AHR2 (rsAHR2) together with a reporter plasmid containing red seabream CYP1A 5'-flanking region were transfected into COS-7 cells. The cells were treated with graded concentrations of seven DRC congeners including 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,4,7,8-HxCDD, 2,3,7,8-TCDF, 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, and PCB126. Both rsAHR1 and rsAHR2 exhibited dose-dependent responses for all the tested congeners. The rsAHR isoform-specific TCDD induction equivalency factors (rsAHR1- and rsAHR2-IEFs) were calculated on the basis of 2,3,7,8-TCDD relative potency derived from the dose-response of each congener. The rsAHR1-IEFs of PeCDD, HxCDD, TCDF, PeCDF, and HxCDF were estimated as 0.17, 0.29, 2.5, 1.5, and 0.27, respectively. For PCB126, no rsAHR1-IEF was given because of less than 10% 2,3,7,8-TCDD maximum response. The rsAHR2-IEFs of PeCDD, HxCDD, TCDF, PeCDF, HxCDF, and PCB126 were estimated as 0.38, 0.13, 1.5, 0.93, 0.20, and 0.0085, respectively. The rsAHR1/2-IEF profiles were different from WHO toxic equivalency factors for fish. In silico docking simulations supported that both rsAHRs have potentials to bind to these congeners. These results suggest that dioxin toxicities may be mediated by both rsAHRs in red seabreams.

  2. Immunological characterization of the aryl hydrocarbon receptor (AHR) knockout rat in the presence and absence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

    PubMed

    Phadnis-Moghe, Ashwini S; Chen, Weimin; Li, Jinpeng; Crawford, Robert B; Bach, Anthony; D'Ingillo, Shawna; Kovalova, Natalia; Suarez-Martinez, Jose E; Kaplan, Barbara L F; Harrill, Joshua A; Budinsky, Robert; Rowlands, J Craig; Thomas, Russell S; Kaminski, Norbert E

    2016-08-10

    The aryl hydrocarbon receptor (AHR) has been extensively characterized for the essential role it plays in mediating the toxic responses elicited by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Despite similarities across animal species, species-specific differences exist in the profile of toxicity and sensitivity to TCDD owing, in part, to differences in the AHR. Newer reports have implicated the importance of AHR in the development and regulation of the immune system. Our present studies seek to further explore the essential role of AHR in lymphoid tissue composition, B cell function and the immunological responses after TCDD administration using the recently established AHR KO rats. Comprehensive immune cell phenotyping showed a decrease in the CD8 + T cell, CD11c + populations and an increase in NKT cells in 3-week-old AHR KO rats compared to the WT controls. The lipopolysaccharide-induced IgM response and proliferation was markedly suppressed in the WT but not in the AHR KO B cells in the presence of TCDD. However, the percentage of LPS-activated IgM + B cells was significantly higher in the AHR KO B cells as compared to that of WT suggesting the role of AHR in regulating the IgM response. The use of an AHR antagonist further alluded to the endogenous role of AHR in regulating B cell responses in the rat. Overall, the studies report for the first time, comprehensive immune cell phenotyping of the AHR KO rat and the endogenous role of AHR in the regulation of B cell function in the rat. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  3. UAV State Estimation Modeling Techniques in AHRS

    NASA Astrophysics Data System (ADS)

    Razali, Shikin; Zhahir, Amzari

    2017-11-01

    Autonomous unmanned aerial vehicle (UAV) system is depending on state estimation feedback to control flight operation. Estimation on the correct state improves navigation accuracy and achieves flight mission safely. One of the sensors configuration used in UAV state is Attitude Heading and Reference System (AHRS) with application of Extended Kalman Filter (EKF) or feedback controller. The results of these two different techniques in estimating UAV states in AHRS configuration are displayed through position and attitude graphs.

  4. DDE and PCB 153 independently induce aryl hydrocarbon receptor (AhR) expression in peripheral blood mononuclear cells.

    PubMed

    Gaspar-Ramírez, Octavio; Pérez-Vázquez, Francisco J; Salgado-Bustamante, Mariana; González-Amaro, Roberto; Hernandez-Castro, Berenice; Pérez-Maldonado, Ivan N

    2015-01-01

    Recent studies have demonstrated that compounds inducing pro-inflammatory cytokines enhance AhR expression. The aim of this study was 2-fold: (1) to determine if two pro-inflammatory compounds, dichlorodiphenyldichloroethylene (DDE) and 2,2',4,4',5,5'-hexa-chlorobiphenyl (PCB 153), independently affect AhR gene expression in peripheral blood mononuclear cells (PBMC); and (2) if affected, to determine whether the mechanism involved was due to AhR activation or to a pro-inflammatory effect of the chemicals. PBMC isolated from healthy individuals were incubated in the presence of DDE (10 µg/ml) and PCB 153 (20 ng/ml) over time and AhR and CYP1A1 expression was assessed with a real-time PCR technique. The results indicated there was over-expression of the AhR mRNA in PBMC when the cells were treated with DDE and PCB 153. No changes in expression levels of CYP1A1 mRNA were found. Importantly, when the cells were exposed to DDE and PCB 153 in the presence of an antagonist of tumor necrosis factor (TNF)-α, the over-expression of AhR was abolished; as expected, the expression of CYP1A1 was unaffected. In conclusion, these studies demonstrated for the first time an increment of AhR expression "in vitro" in PBMC treated with two pro-inflammatory environmental pollutants, DDE and PCB153. Moreover, the over-expression of AhR was dependent of TNFα induced by DDE and PCB 153 and was independent of AhR activation.

  5. Lymphocyte-specific protein tyrosine kinase (LCK) is involved in the aryl hydrocarbon receptor (AHR)-mediated impairment of immunoglobulin secretion in human primary B cells.

    PubMed

    Zhou, Jiajun; Zhang, Qiang; Henriquez, Joseph E; Crawford, Robert B; Kaminski, Norbert E

    2018-05-31

    The aryl hydrocarbon receptor (AHR) is a cytosolic ligand-activated transcription factor involved in xenobiotic sensing, cell cycle regulation and cell development. In humans, the activation of AHR by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a high affinity AHR-ligand, impairs the secretion of immunoglobulin M (IgM) to suppress humoral immunity. However, the mechanisms bridging the activation of AHR and the impairment of IgM secretion by human primary B cells remain poorly understood. Recent transcriptomic analysis revealed upregulation of lymphocyte-specific protein tyrosine kinase (LCK) in AHR activated human primary B cells. LCK is a well-characterized tyrosine kinase that phosphorylates critical signaling proteins involved in activation and cytokine production in T cells. Conversely, the role of LCK in human primary B cells is not well understood. In the current studies, we have verified the transcriptomic finding by detecting AHR-mediated upregulation of LCK protein in human primary B cells. We also confirmed the role of AHR in the upregulation of LCK by using a specific AHR antagonist, which abolished the AHR-mediated increase of LCK. Furthermore, we have confirmed the role of LCK in the AHR-mediated suppression of IgM by using LCK specific inhibitors, which restored IgM secretion by human B cells in the presence of TCDD. Collectively, the current studies demonstrate a novel role of LCK in IgM secretion and provide new insights into the mechanism for AHR-mediated impairment of immunoglobulin secretion by human primary B cells.

  6. Involvement of the cytokine-IDO1-AhR loop in zinc oxide nanoparticle-induced acute pulmonary inflammation.

    PubMed

    Ho, Chia-Chi; Lee, Hui-Ling; Chen, Chao-Yu; Luo, Yueh-Hsia; Tsai, Ming-Hsien; Tsai, Hui-Ti; Lin, Pinpin

    2017-04-01

    Zinc oxide nanoparticles (ZnONPs) are widely used in our daily life, such as in sunscreens and electronic nanodevices. However, pulmonary exposure to ZnONPs causes acute pulmonary inflammation, which is considered as an initial event for various respiratory diseases. Thus, elucidation of the underlying cellular mechanisms of ZnONPs can help us in predicting their potential effects in respiratory diseases. In this study, we observed that ZnONPs increased proinflammatory cytokines, accompanied with an increased expression of aryl hydrocarbon receptor (AhR) and its downstream target cytochrome P450 1A1 (CYP1A1) in macrophages in vitro and in mouse lung epithelia in vivo. Moreover, zinc nitrate, but not silica or titanium dioxide nanoparticles (NPs), had similar effects on macrophages, indicating that the zinc element or ion released from ZnONPs is likely responsible for the activation of the AhR pathway. Cotreatment with an AhR antagonist or AhR knockout reduced ZnONPs-induced cytokine secretion in macrophages or mice, respectively. Furthermore, kynurenine (KYN), an endogenous AhR agonist and a tryptophan metabolite catalyzed by indoleamine 2,3-dioxygenase (IDO), was increased in the serums of mice that aspirated ZnONPs. Consistently, ZnONPs increased IDO1 expression in lung cells in vitro and in vivo. Finally, AhR knockout reduced ZnONPs-induced pulmonary inflammation, cytokine secretion and KYN production in mice, suggesting that AhR activation is involved in ZnONPs-induced cytokine secretion and pulmonary inflammation. In summary, we demonstrated that the pulmonary exposure of ZnONPs stimulated the cytokine-IDO1-AhR loop in the lungs, which has been implied to play roles in immune dysfunctions.

  7. Feedback control of AHR signalling regulates intestinal immunity.

    PubMed

    Schiering, Chris; Wincent, Emma; Metidji, Amina; Iseppon, Andrea; Li, Ying; Potocnik, Alexandre J; Omenetti, Sara; Henderson, Colin J; Wolf, C Roland; Nebert, Daniel W; Stockinger, Brigitta

    2017-02-09

    The aryl hydrocarbon receptor (AHR) recognizes xenobiotics as well as natural compounds such as tryptophan metabolites, dietary components and microbiota-derived factors, and it is important for maintenance of homeostasis at mucosal surfaces. AHR activation induces cytochrome P4501 (CYP1) enzymes, which oxygenate AHR ligands, leading to their metabolic clearance and detoxification. Thus, CYP1 enzymes have an important feedback role that curtails the duration of AHR signalling, but it remains unclear whether they also regulate AHR ligand availability in vivo. Here we show that dysregulated expression of Cyp1a1 in mice depletes the reservoir of natural AHR ligands, generating a quasi AHR-deficient state. Constitutive expression of Cyp1a1 throughout the body or restricted specifically to intestinal epithelial cells resulted in loss of AHR-dependent type 3 innate lymphoid cells and T helper 17 cells and increased susceptibility to enteric infection. The deleterious effects of excessive AHR ligand degradation on intestinal immune functions could be counter-balanced by increasing the intake of AHR ligands in the diet. Thus, our data indicate that intestinal epithelial cells serve as gatekeepers for the supply of AHR ligands to the host and emphasize the importance of feedback control in modulating AHR pathway activation.

  8. The aryl hydrocarbon receptor (AHR) transcription factor regulates megakaryocytic polyploidization

    PubMed Central

    Lindsey, Stephan; T. Papoutsakis, Eleftherios

    2012-01-01

    Summary We propose that the aryl hydrocarbon receptor (AHR) is a novel transcriptional regulator of megakaryopoietic polyploidization. Functional evidence was obtained that AHR impacts in vivo megakaryocytic differentiation and maturation; compared to wild-type mice, AHR-null mice had lower platelet counts, fewer numbers of newly synthesized platelets, increased bleeding times and lower-ploidy megakaryocytes (Mks). AHR mRNA increased 3·6-fold during ex vivo megakaryocytic differentiation, but reduced or remained constant during parallel isogenic granulocytic or erythroid differentiation. We interrogated the role of AHR in megakaryopoiesis using a validated Mk model of megakaryopoiesis, the human megakaryoblastic leukaemia CHRF cell line. Upon CHRF Mk differentiation, AHR mRNA and protein levels increased, AHR protein shifted from the cytoplasm to the nucleus and AHR binding to its consensus DNA binding sequence increased. Protein and mRNA levels of the AHR transcriptional target HES1 also increased. Mk differentiation of CHRF cells where AHR or HES1 was knocked-down using RNAi resulted in lower ploidy distributions and cells that were incapable of reaching ploidy classes ≥16n. AHR knockdown also resulted in increased DNA synthesis of lower ploidy cells, without impacting apoptosis. Together, these data support a role for AHR in Mk polyploidization and in vivo platelet function, and warrant further detailed investigations. PMID:21226706

  9. The aryl hydrocarbon receptor (AHR) transcription factor regulates megakaryocytic polyploidization.

    PubMed

    Lindsey, Stephan; Papoutsakis, Eleftherios T

    2011-02-01

    We propose that the aryl hydrocarbon receptor (AHR) is a novel transcriptional regulator of megakaryopoietic polyploidization. Functional evidence was obtained that AHR impacts in vivo megakaryocytic differentiation and maturation; compared to wild-type mice, AHR-null mice had lower platelet counts, fewer numbers of newly synthesized platelets, increased bleeding times and lower-ploidy megakaryocytes (Mks). AHR mRNA increased 3·6-fold during ex vivo megakaryocytic differentiation, but reduced or remained constant during parallel isogenic granulocytic or erythroid differentiation. We interrogated the role of AHR in megakaryopoiesis using a validated Mk model of megakaryopoiesis, the human megakaryoblastic leukaemia CHRF cell line. Upon CHRF Mk differentiation, AHR mRNA and protein levels increased, AHR protein shifted from the cytoplasm to the nucleus and AHR binding to its consensus DNA binding sequence increased. Protein and mRNA levels of the AHR transcriptional target HES1 also increased. Mk differentiation of CHRF cells where AHR or HES1 was knocked-down using RNAi resulted in lower ploidy distributions and cells that were incapable of reaching ploidy classes ≥16n. AHR knockdown also resulted in increased DNA synthesis of lower ploidy cells, without impacting apoptosis. Together, these data support a role for AHR in Mk polyploidization and in vivo platelet function, and warrant further detailed investigations. © 2011 Blackwell Publishing Ltd.

  10. Unprecedented genomic diversity of AhR1 and AhR2 genes in Atlantic salmon (Salmo salar L.).

    PubMed

    Hansson, Maria C; Wittzell, Håkan; Persson, Kerstin; von Schantz, Torbjörn

    2004-06-24

    Aryl hydrocarbon receptor (AhR) genes encode proteins involved in mediating the toxic responses induced by several environmental pollutants. Here, we describe the identification of the first two AhR1 (alpha and beta) genes and two additional AhR2 (alpha and beta) genes in the tetraploid species Atlantic salmon (Salmo salar L.) from a cosmid library screening. Cosmid clones containing genomic salmon AhR sequences were isolated using a cDNA clone containing the coding region of the Atlantic salmon AhR2gamma as a probe. Screening revealed 14 positive clones, from which four were chosen for further analyses. One of the cosmids contained genomic AhR sequences that were highly similar to the rainbow trout (Oncorhynchus mykiss) AhR2alpha and beta genes. SMART RACE amplified two complete, highly similar but not identical AhR type 2 sequences from salmon cDNA, which from phylogenetic analyses were determined as the rainbow trout AhR2alpha and beta orthologs. The salmon AhR2alpha and beta encode proteins of 1071 and 1058 residues, respectively, and encompass characteristic AhR sequence elements like a basic-helix-loop-helix (bHLH) and two PER-ARNT-SIM (PAS) domains. Both genes are transcribed in liver, spleen and muscle tissues of adult salmon. A second cosmid contained partial sequences, which were identical to the previously characterized AhR2gamma gene. The last two cosmids contained partial genomic AhR sequences, which were more similar to other AhR type 1 fish genes than the four characterized salmon AhR2 genes. However, attempts to amplify the corresponding complete cDNA sequences of the inserts proved very difficult, suggesting that these genes are non-functional or very weakly transcribed in the examined tissues. Phylogenetic analyses of the conserved regions did, however, clearly indicate that these two AhRs belong to the AhR type 1 clade and have been assigned as the Atlantic salmon AhR1alpha and AhR1beta genes. Taken together, these findings demonstrate that

  11. T-cell expression of AhR inhibits the maintenance of pTreg cells in the gastrointestinal tract in acute GVHD.

    PubMed

    Dant, Trisha A; Lin, Kaifeng L; Bruce, Danny W; Montgomery, Stephanie A; Kolupaev, Oleg V; Bommiasamy, Hemamalini; Bixby, Lisa M; Woosley, John T; McKinnon, Karen P; Gonzalez, Frank J; Blazar, Bruce R; Vincent, Benjamin G; Coghill, James M; Serody, Jonathan S

    2017-07-20

    The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that affects the function and development of immune cells. Here, we show that recipient mice receiving AhR -/- T cells have improved survival and decreased acute graft-versus-host disease (aGVHD) in 2 different murine allogeneic bone marrow transplant (BMT) models. We also show that CD4 + T cells lacking AhR demonstrate reduced accumulation in secondary lymphoid tissue because of low levels of proliferation 4 days after BMT. Additionally, we found a significant increase in the quantity of peripherally induced regulatory donor T (pT reg ) cells in the colon of recipients transplanted with AhR -/- T cells 14 days after transplant. Blockade of AhR using a clinically available AhR antagonist greatly enhanced the in vitro generation of inducible T reg (iT reg ) cells from naïve CD4 + human T cells. We have identified AhR as a novel target on donor T cells that is critical to the pathogenesis of aGVHD.

  12. Human and rodent aryl hydrocarbon receptor (AHR): from mediator of dioxin toxicity to physiologic AHR functions and therapeutic options.

    PubMed

    Bock, Karl Walter

    2017-04-01

    Metabolism of aryl hydrocarbons and toxicity of dioxins led to the discovery of the aryl hydrocarbon receptor (AHR). Tremendous advances have been made on multiplicity of AHR signaling and identification of endogenous ligands including the tryptophan metabolites FICZ and kynurenine. However, human AHR functions are still poorly understood due to marked species differences as well as cell-type- and cell context-dependent AHR functions. Observations in dioxin-poisoned individuals may provide hints to physiologic AHR functions in humans. Based on these observations three human AHR functions are discussed: (1) Chemical defence and homeostasis of endobiotics. The AHR variant Val381 in modern humans leads to reduced AHR affinity to aryl hydrocarbons in comparison with Neanderthals and primates expressing the Ala381 variant while affinity to indoles remains unimpaired. (2) Homeostasis of stem/progenitor cells. Dioxins dysregulate homeostasis in sebocyte stem cells. (3) Modulation of immunity. In addition to microbial defence, AHR may be involved in a 'disease tolerance defence pathway'. Further characterization of physiologic AHR functions may lead to therapeutic options.

  13. Cross-regulatory circuit between AHR and microbiota.

    PubMed

    Ji, Jian; Qu, Hao

    2018-01-29

    The gut microbes have a close symbiotic relationship with their host. Interactions between host and the microbiota affect the nutritional, immunological, and physiological status of the host. The aryl hydrocarbon receptor (AHR) is a ligand activated transcription factor that mediates the toxicity of xenobiotics. Recently, the relationship between the gut microbiota and AHR has attracted the attention of many researchers. The AHR influences the intestinal microbiota population and mediates host-microbe homeostasis. Interestingly, the gut microbiota also produces ligands of AHR from bacterial metabolism and thereby activates the AHR signaling pathway. This review presents current knowledge of the cross-regulatory circuit between the AHR and intestinal microbiota. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  14. AhR and Arnt differentially regulate NF-κB signaling and chemokine responses in human bronchial epithelial cells

    PubMed Central

    2014-01-01

    Background The aryl hydrocarbon receptor (AhR) has gradually emerged as a regulator of inflammation in the lung and other tissues. AhR may interact with the p65-subunit of the nuclear factor (NF)-κB transcription factors, but reported outcomes of AhR/NF-κB-interactions are conflicting. Some studies suggest that AhR possess pro-inflammatory activities while others suggest that AhR may be anti-inflammatory. The present study explored the impact of AhR and its binding partner AhR nuclear translocator (Arnt) on p65-activation and two differentially regulated chemokines, CXCL8 (IL-8) and CCL5 (RANTES), in human bronchial epithelial cells (BEAS-2B). Results Cells were exposed to CXCL8- and CCL5-inducing chemicals, 1-nitropyrene (1-NP) and 1-aminopyrene (1-AP) respectively, or the synthetic double-stranded RNA analogue, polyinosinic-polycytidylic acid (Poly I:C) which induced both chemokines. Only CXCL8, and not CCL5, appeared to be p65-dependent. Yet, constitutively active unligated AhR suppressed both CXCL8 and CCL5, as shown by siRNA knock-down and the AhR antagonist α-naphthoflavone. Moreover, AhR suppressed activation of p65 by TNF-α and Poly I:C as assessed by luciferase-assay and p65-phosphorylation at serine 536, without affecting basal p65-activity. In contrast, Arnt suppressed only CXCL8, but did not prevent the p65-activation directly. However, Arnt suppressed expression of the NF-κB-subunit RelB which is under transcriptional regulation by p65. Furthermore, AhR-ligands alone at high concentrations induced a moderate CXCL8-response, without affecting CCL5, but suppressed both CXCL8 and CCL5-responses by Poly I:C. Conclusion AhR and Arnt may differentially and independently regulate chemokine-responses induced by both inhaled pollutants and pulmonary infections. Constitutively active, unligated AhR suppressed the activation of p65, while Arnt may possibly interfere with the action of activated p65. Moreover, ligand-activated AhR suppressed CXCL8 and CCL5

  15. Molecular modeling of the AhR structure and interactions can shed light on ligand-dependent activation and transformation mechanisms.

    PubMed

    Bonati, Laura; Corrada, Dario; Tagliabue, Sara Giani; Motta, Stefano

    2017-02-01

    Molecular modeling has given important contributions to elucidation of the main stages in the AhR signal transduction pathway. Despite the lack of experimentally determined structures of the AhR functional domains, information derived from homologous systems has been exploited for modeling their structure and interactions. Homology models of the AhR PASB domain have provided information on the binding cavity and contributed to elucidate species-specific differences in ligand binding. Molecular Docking simulations of the ligand binding process have given insights into differences in binding of diverse agonists, antagonists, and selective AhR modulators, and their application to virtual screening of large databases of compounds have allowed identification of novel AhR ligands. Recently available structural information on protein-protein and protein-DNA complexes of other bHLH-PAS systems has opened the way for modeling the AhR:ARNT dimer structure and investigating the mechanisms of AhR transformation and DNA binding. Future research directions should include simulation of the protein dynamics to obtain a more reliable description of intermolecular interactions involved in signal transmission.

  16. TOXICITY OF AHR AGONISTS TO FISH EARLY LIFE STAGES

    EPA Science Inventory

    Fish early life stages are exceptionally sensitive to the lethal toxicity of chemicals that act as arylhydrocarbon receptor (AhR) agonists. Toxicity characterizations based on 2,3,7,8-tetrachlorodibenzo-p-dioxin, generally the most potent AhR agonist, support the toxicity equiva...

  17. Teratogenic impact of dioxin-activated AHR in laboratory animals

    EPA Science Inventory

    AHR and ARNT are expressed in mouse and human palatal shelves and in the urinary tract of the mouse fetus. AHR expression, translocation to the nucleus, binding to DRE, and activation are required for mediation of TCDD-induction of CP and HN. Although the human palate requires a ...

  18. Cigarette smoke-induced cell cycle arrest in spermatocytes [GC-2spd(ts)] is mediated through crosstalk between Ahr-Nrf2 pathway and MAPK signaling.

    PubMed

    Esakky, Prabagaran; Hansen, Deborah A; Drury, Andrea M; Moley, Kelle H

    2015-02-01

    Our earlier studies have demonstrated that the cigarette smoke in the form of cigarette smoke condensate (CSC) causes growth arrest of a mouse spermatocyte cell line [GC-2spd(ts)] through activation of the AHR-NRF2 pathway. The present study demonstrates the CSC-activated p38 and ERK MAPK signaling in GC-2spd(ts) via arylhydrocarbon receptor (AHR). Pharmacological inhibition by using AHR-antagonist, or p38 MAPK and ERK (MEK1) inhibitors significantly abrogates CSC-induced growth arrest by AHR and MAPK inactivation. QRT-PCR, western blot, and immunofluorescence of Ahr-target of Nrf2, and stress-inducible growth suppressive Atf3 and E2f4 following treatments indicate a crosstalk among these pathways. Regulation of Atf3 by Nrf2 and Ahr through RNA interference suggests the existence of a cross-regulatory loop between the targets. CSC induction of E2f4 via Atf3 and its regulation by pharmacological inhibitors reveal a possible regulatory mechanism of growth inhibitory CSC. SiRNA silencing of Ahr, Nrf2, Atf3, and E2f4 genes and downregulation of cyclins by CSC corroborate the growth inhibitory effect of cigarette smoke. Thus, the data obtained suggest that the CSC-mediated MAPKs and AHR-NRF2 crosstalks lay the molecular basis for the growth arrest and cell death of spermatocytes. © The Author (2014). Published by Oxford University Press on behalf of Journal of Molecular Cell Biology, IBCB, SIBS, CAS. All rights reserved.

  19. Characterizing the role of endothelin-1 in the progression of cardiac hypertrophy in aryl hydrocarbon receptor (AhR) null mice

    SciTech Connect

    Lund, Amie K.; Goens, M. Beth; Nunez, Bethany A.

    2006-04-15

    The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor characterized to play a role in detection and adaptation to environmental stimuli. Genetic deletion of AhR results in hypertension, and cardiac hypertrophy and fibrosis, associated with elevated plasma angiotensin II (Ang II) and endothelin-1 (ET-1), thus AhR appears to contribute to cardiovascular homeostasis. In these studies, we tested the hypothesis that ET-1 mediates cardiovascular pathology in AhR null mice via ET{sub A} receptor activation. First, we determine the time courses of cardiac hypertrophy, and of plasma and tissue ET-1 expression in AhR wildtype and null mice. AhR null mice exhibitedmore » increases in heart-to-body weight ratio and age-related expression of cardiac hypertrophy markers, {beta}-myosin heavy chain ({beta}-MHC), and atrial natriuretic factor (ANF), which were significant at 2 months. Similarly, plasma and tissue ET-1 expression was significantly elevated at 2 months and increased further with age. Second, AhR null mice were treated with ET{sub A} receptor antagonist, BQ-123 (100 nmol/kg/day), for 7, 28, or 58 days and blood pressure, cardiac fibrosis, and cardiac hypertrophy assessed, respectively. BQ-123 for 7 days significantly reduced mean arterial pressure in conscious, catheterized mice. BQ-123 for 28 days significantly reduced the histological appearance of cardiac fibrosis. Treatment for 58 days significantly reduced cardiac mass, assessed by heart weight, echocardiography, and {beta}-MHC and ANF expression; and reduced cardiac fibrosis as determined by osteopontin and collagen I mRNA expression. These findings establish ET-1 and the ET{sub A} receptor as primary determinants of hypertension and cardiac pathology in AhR null mice.« less

  20. Microbiome-Derived Tryptophan Metabolites and Their Aryl Hydrocarbon Receptor-Dependent Agonist and Antagonist Activities

    PubMed Central

    Jin, Un-Ho; Lee, Syng-Ook; Sridharan, Gautham; Lee, Kyongbum; Davidson, Laurie A.; Jayaraman, Arul; Chapkin, Robert S.; Alaniz, Robert

    2014-01-01

    The tryptophan metabolites indole, indole-3-acetate, and tryptamine were identified in mouse cecal extracts and fecal pellets by mass spectrometry. The aryl hydrocarbon receptor (AHR) agonist and antagonist activities of these microbiota-derived compounds were investigated in CaCo-2 intestinal cells as a model for understanding their interactions with colonic tissue, which is highly aryl hydrocarbon (Ah)–responsive. Activation of Ah-responsive genes demonstrated that tryptamine and indole 3-acetate were AHR agonists, whereas indole was an AHR antagonist that inhibited TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin)–induced CYP1A1 expression. In contrast, the tryptophan metabolites exhibited minimal anti-inflammatory activities, whereas TCDD decreased phorbol ester-induced CXCR4 [chemokine (C-X-C motif) receptor 4] gene expression, and this response was AHR dependent. These results demonstrate that the tryptophan metabolites indole, tryptamine, and indole-3-acetate modulate AHR-mediated responses in CaCo-2 cells, and concentrations of indole that exhibit AHR antagonist activity (100–250 μM) are detected in the intestinal microbiome. PMID:24563545

  1. Simulator for SUPO, a Benchmark Aqueous Homogeneous Reactor (AHR)

    SciTech Connect

    Klein, Steven Karl; Determan, John C.

    2015-10-14

    A simulator has been developed for SUPO (Super Power) an aqueous homogeneous reactor (AHR) that operated at Los Alamos National Laboratory (LANL) from 1951 to 1974. During that period SUPO accumulated approximately 600,000 kWh of operation. It is considered the benchmark for steady-state operation of an AHR. The SUPO simulator was developed using the process that resulted in a simulator for an accelerator-driven subcritical system, which has been previously reported.

  2. AHR/CYP1A1 interplay triggers lymphatic barrier breaching in breast cancer spheroids by inducing 12(S)-HETE synthesis.

    PubMed

    Nguyen, Chi Huu; Brenner, Stefan; Huttary, Nicole; Atanasov, Atanas Georgiev; Dirsch, Verena Maria; Chatuphonprasert, Waranya; Holzner, Sivio; Stadler, Serena; Riha, Juliane; Krieger, Sigurd; de Martin, Rainer; Bago-Horvath, Zsuzsanna; Krupitza, Georg; Jäger, Walter

    2016-11-15

    A causal link between overexpression of aryl hydrocarbon receptor (AHR) and its target cytochrome P450 1A1 (CYP1A1) and metastatic outgrowth of various cancer entities has been established. Nevertheless, the mechanism how AHR/CYP1A1 support metastasis formation is still little understood. In vitro we discovered a potential mechanism facilitating tumour dissemination based on the production of 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE). Utilising a three-dimensional lymph endothelial cell (LEC) monolayer & MDA-MB231 breast cancer cell spheroid co-culture model in combination with knock-down approach allowed elucidation of the molecular/biochemical basis of AHR/CYP1A1-induced tumour breaching through the LEC barrier. Enzyme immunoassay evidenced the potential of recombinant CYP1A1 to synthesise 12(S)-HETE in vitro and qPCR and Western blotting measured gene and protein expression in specific experimental settings. In detail, AHR induced CYP1A1 expression and 12(S)-HETE secretion in tumour spheroids, which caused LEC junction retraction thereby forming large discontinuities allowing transmigration of the tumour. This was enforced by the activating AHR ligand 6-formylindolo (3,3-b)carbazole (FICZ), or inhibited by the AHR antagonist 3,3’-diindolylmethane (DIM) as well as by siRNA against AHR and CYP1A1. AHR and NF-κB were negatively cross talking and therefore, the inhibition of AHR (but not CYP1A1) induced RELA, RELB, NFKB1, NFKB2 and the NF-κB target MMP1, which itself promotes tumour intravasation by a mechanism that is different from 12(S)-HETE. Conversely, the inhibition of NFKB2 induced AHR, CYP1A1 and 12(S)-HETE synthesis. The approved clinical drugs guanfacine and vinpocetine, which inhibit CYP1A1 and NF-κB, respectively, significantly inhibited LEC barrier breaching in vitro indicating an option to reduce metastatic dissemination.

  3. Buprenorphine, Norbuprenorphine, R-Methadone, and S-Methadone Upregulate BCRP/ABCG2 Expression by Activating Aryl Hydrocarbon Receptor in Human Placental Trophoblasts

    PubMed Central

    Neradugomma, Naveen K.; Liao, Michael Z.

    2017-01-01

    Opioid dependence during pregnancy is a rising concern. Maintaining addicted pregnant women on long-acting opioid receptor agonist is the most common strategy to manage drug abuse in pregnant women. Methadone (MET) and buprenorphine (BUP) are widely prescribed for opiate maintenance therapy. Norbuprenorphine (NBUP) is the primary active metabolite of BUP. These medications can cross the placenta to the fetus, leading to postpartum neonatal abstinence syndrome. Despite their use during pregnancy, little is known about the cellular changes in the placenta brought about by these drugs. In this study, we showed that BUP, NBUP, and MET at clinically relevant plasma concentrations significantly induced BCRP mRNA up to 10-fold in human model placental JEG3 and BeWo cells and in primary human villous trophoblasts, and this induction was abrogated by CH223191, an aryl hydrocarbon receptor (AhR)-specific antagonist. These drugs increased AhR recruitment onto the AhR-response elements and significantly induced breast cancer resistance protein (BCRP) gene transcription. AhR overexpression further increased BCRP mRNA and protein expression. Knockdown of AhR by shRNA decreased BCRP expression, and this decrease was reversed by rescuing AhR expression. Finally, induction of BCRP expression in JEG3 and BeWo cells was accompanied by an increase in its efflux activity. Collectively, we have demonstrated, for the first time, that BUP, NBUP, and MET are potent AhR agonists and can induce BCRP in human placental trophoblasts by activating AhR. Given the critical role of BCRP in limiting fetal exposure to drugs and xenobiotics, long-term use of these medications may affect fetal drug exposure by altering BCRP expression in human placenta. PMID:27974484

  4. Genetic dissection of endothelial transcriptional activity of zebrafish aryl hydrocarbon receptors (AHRs).

    PubMed

    Sugden, Wade W; Leonardo-Mendonça, Roberto C; Acuña-Castroviejo, Darío; Siekmann, Arndt F

    2017-01-01

    The aryl hydrocarbon receptor (AHR) is a basic helix-loop-helix transcription factor conserved across phyla from flies to humans. Activated by a number of endogenous ligands and environmental toxins, studies on AHR function and gene regulation have largely focused on a toxicological perspective relating to aromatic hydrocarbons generated by human activities and the often-deleterious effects of exposure on vertebrates mediated by AHR activation. A growing body of work has highlighted the importance of AHR in physiologic processes, including immune cell differentiation and vascular patterning. Here we dissect the contribution of the 3 zebrafish AHRs, ahr1a, ahr1b and ahr2, to endothelial cyp1a1/b1 gene regulation under physiologic conditions and upon exposure to the AHR ligand Beta-naphthoflavone. We show that in fish multiple AHRs are functional in the vasculature, with vessel-specific differences in the ability of ahr1b to compensate for the loss of ahr2 to maintain AHR signaling. We further provide evidence that AHR can regulate the expression of the chemokine receptor cxcr4a in endothelial cells, a regulatory mechanism that may provide insight into AHR function in the endothelium.

  5. Regulation of subcellular localization of the Aryl Hydrocarbon Receptor (AhR)

    USGS Publications Warehouse

    Richter, Catherine A.; Tillitt, Donald E.; Hannink, Mark

    2001-01-01

    The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the toxicity of dioxin and other xenobiotics. In the absence of exogenous ligand, AhR is cytosolic. We investigated how AhR is retained in the cytosol and how dioxin induces AhR to move to the nucleus. Disruption of nuclear export of AhR by the nuclear export inhibitor leptomycin B (LMB) or by mutation of the AhR nuclear export signal resulted in nuclear accumulation of AhR in the absence of exogenous ligand. Mutation of the AhR nuclear localization signal resulted in defects in nuclear import of AhR in both the presence and the absence of exogenous ligand. Dioxin treatment caused a more rapid accumulation of AhR in the nucleus than LMB treatment. In the presence of both dioxin and LMB, nuclear accumulation of AhR was more rapid than in the presence of dioxin alone. Our results show that AhR shuttles between the nucleus and the cytosol in the absence of exogenous ligand. Binding of ligand induces an increase in the rate of nuclear import of AhR but does not eliminate nuclear export of AhR.

  6. Diversity as Opportunity: Insights from 600 Million Years of AHR Evolution.

    PubMed

    Hahn, Mark E; Karchner, Sibel I; Merson, Rebeka R

    2017-02-01

    The aryl hydrocarbon receptor (AHR) was for many years of interest only to pharmacologists and toxicologists. However, this protein has fundamental roles in biology that are being revealed through studies in diverse animal species. The AHR is an ancient protein. AHR homologs exist in most major groups of modern bilaterian animals, including deuterostomes (chordates, hemichordates, echinoderms) and the two major clades of protostome invertebrates [ecdysozoans (e.g. arthropods and nematodes) and lophotrochozoans (e.g. molluscs and annelids)]. AHR homologs also have been identified in cnidarians such as the sea anemone Nematostella and in the genome of Trichoplax , a placozoan. Bilaterians, cnidarians, and placozoans form the clade Eumetazoa , whose last common ancestor lived approximately 600 million years ago (MYA). The presence of AHR homologs in modern representatives of all these groups indicates that the original eumetazoan animal possessed an AHR homolog. Studies in invertebrates and vertebrates reveal parallel functions of AHR in the development and function of sensory neural systems, suggesting that these may be ancestral roles. Vertebrate animals are characterized by the expansion and diversification of AHRs, via gene and genome duplications, from the ancestral protoAHR into at least five classes of AHR-like proteins: AHR, AHR1, AHR2, AHR3, and AHRR. The evolution of multiple AHRs in vertebrates coincided with the acquisition of high-affinity binding of halogenated and polynuclear aromatic hydrocarbons and the emergence of adaptive functions involving regulation of xenobiotic-metabolizing enzymes and roles in adaptive immunity. The existence of multiple AHRs may have facilitated subfunction partitioning and specialization of specific AHR types in some taxa. Additional research in diverse model and non-model species will continue to enrich our understanding of AHR and its pleiotropic roles in biology and toxicology.

  7. Diversity as Opportunity: Insights from 600 Million Years of AHR Evolution

    PubMed Central

    Hahn, Mark E.; Karchner, Sibel I.; Merson, Rebeka R.

    2017-01-01

    The aryl hydrocarbon receptor (AHR) was for many years of interest only to pharmacologists and toxicologists. However, this protein has fundamental roles in biology that are being revealed through studies in diverse animal species. The AHR is an ancient protein. AHR homologs exist in most major groups of modern bilaterian animals, including deuterostomes (chordates, hemichordates, echinoderms) and the two major clades of protostome invertebrates [ecdysozoans (e.g. arthropods and nematodes) and lophotrochozoans (e.g. molluscs and annelids)]. AHR homologs also have been identified in cnidarians such as the sea anemone Nematostella and in the genome of Trichoplax, a placozoan. Bilaterians, cnidarians, and placozoans form the clade Eumetazoa, whose last common ancestor lived approximately 600 million years ago (MYA). The presence of AHR homologs in modern representatives of all these groups indicates that the original eumetazoan animal possessed an AHR homolog. Studies in invertebrates and vertebrates reveal parallel functions of AHR in the development and function of sensory neural systems, suggesting that these may be ancestral roles. Vertebrate animals are characterized by the expansion and diversification of AHRs, via gene and genome duplications, from the ancestral protoAHR into at least five classes of AHR-like proteins: AHR, AHR1, AHR2, AHR3, and AHRR. The evolution of multiple AHRs in vertebrates coincided with the acquisition of high-affinity binding of halogenated and polynuclear aromatic hydrocarbons and the emergence of adaptive functions involving regulation of xenobiotic-metabolizing enzymes and roles in adaptive immunity. The existence of multiple AHRs may have facilitated subfunction partitioning and specialization of specific AHR types in some taxa. Additional research in diverse model and non-model species will continue to enrich our understanding of AHR and its pleiotropic roles in biology and toxicology. PMID:28286876

  8. An endogenous aryl hydrocarbon receptor (AhR) ligand, ITE induces regulatory T cells (Tregs) and ameliorates experimental colitis.

    PubMed

    Abron, Jessicca D; Singh, Narendra P; Mishra, Manoj K; Price, Robert L; Nagarkatti, Mitzi; Nagarkatti, Prakash S; Singh, Udai P

    2018-04-19

    Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory condition that affects millions of people with high morbidity and health-care cost. The precise etiology of IBD is unknown, but clear evidence suggests that intestinal inflammation is caused by an excessive immune response to mucosal antigens. Recent studies have shown that activation of the aryl hydrocarbon receptor (AhR) induces regulatory T cells (Tregs) and suppresses autoimmune diseases. In the current study, we investigated if nontoxic ligand of AhR, 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), can attenuate dextran sodium sulphate (DSS)-induced colitis. Our studies demonstrated that in mice that received ITE treatment, in-vivo colitis pathogenesis, including a decrease in body weight, was significantly reversed along with the systemic and intestinal inflammatory cytokines. ITE increased the expression of Tregs in spleen, mesenteric lymph nodes (MLNs) and colon lamina propria lymphocytes (cLPL) of mice with colitis when compared to controls. This induction of Tregs was reversed by AhR antagonist treatment in-vitro. ITE treatment also increased dendritic cells (DCs; CD11c+) and decreased F4/80+ (macrophage) from the spleen, MLNs and cLPL in mice with colitis. ITE also reversed the systemic and intestinal frequency of CD4+T cells during colitis and suppressed inflammatory cytokines including IFN-γ, TNF-α, IL-17, IL-6 and IL-1 as well as induced IL-10 levels. These findings suggest that ITE attenuates colitis through induction of Tregs and reduction in inflammatory CD4+ T cells and cytokines. Thus, our work demonstrates that the nontoxic endogenous AhR ligand ITE, may serve as a therapeutic modality to treat IBD.

  9. Hexachlorobenzene induces cell proliferation, and aryl hydrocarbon receptor expression (AhR) in rat liver preneoplastic foci, and in the human hepatoma cell line HepG2. AhR is a mediator of ERK1/2 signaling, and cell cycle regulation in HCB-treated HepG2 cells.

    PubMed

    de Tomaso Portaz, Ana Clara; Caimi, Giselle Romero; Sánchez, Marcela; Chiappini, Florencia; Randi, Andrea S; Kleiman de Pisarev, Diana L; Alvarez, Laura

    2015-10-02

    are mediated by ERK1/2. Pretreatment with an AhR antagonist, prevented HCB-induced PCNA protein levels, ERK1/2 phosphorylation and alterations in cell cycle distribution. These results demonstrate that HCB-induced HepG2 proliferation and cell cycle progression depend on ERK1/2 phosphorylation which is mediated by the AhR. Our results provide a clue to the molecular events involved in the mechanism of action of HCB-induced hepatocarcinogenesis. Copyright © 2015. Published by Elsevier Ireland Ltd.

  10. Transcript variations, phylogenetic tree and chromosomal localization of porcine aryl hydrocarbon receptor (AhR) and AhR nuclear translocator (ARNT) genes.

    PubMed

    Sadowska, Agnieszka; Paukszto, Lukasz; Nynca, Anna; Szczerbal, Izabela; Orlowska, Karina; Swigonska, Sylwia; Ruszkowska, Monika; Molcan, Tomasz; Jastrzebski, Jan P; Panasiewicz, Grzegorz; Ciereszko, Renata E

    2017-03-01

    Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor best known for mediating xenobiotic-induced toxicity. AhR requires aryl hydrocarbon receptor nuclear translocator (ARNT) to form an active transcription complex and promote the activation of genes which have dioxin responsive element in their regulatory regions. The present study was performed to determine the complete cDNA sequences of porcine AhR and ARNT genes and their chromosomal localization. Total RNA from porcine livers were used to obtain the sequence of the entire porcine transcriptome by next-generation sequencing (NGS; lllumina HiSeq2500). In addition, both, in silico analysis and fluorescence in situ hybridization (FISH) were used to determine chromosomal localization of porcine AhR and ARNT genes. In silico analysis of nucleotide sequences showed that there were two transcript variants of AhR and ARNT genes in the pig. In addition, computer analysis revealed that AhR gene in the pig is located on chromosome 9 and ARNT on chromosome 4. The results of FISH experiment confirmed the localization of porcine AhR and ARNT genes. In the present study, for the first time, the full cDNAs of AhR and ARNT were demonstrated in the pig. In future, it would be interesting to determine the tissue distribution of AhR and ARNT transcript variants in the pig and to test whether these variants are associated with different biological functions and/or different activation pathways.

  11. In vitro re-expression of the aryl hydrocarbon receptor (Ahr) in cultured Ahr-deficient mouse antral follicles partially restores the phenotype to that of cultured wild-type mouse follicles.

    PubMed

    Ziv-Gal, A; Gao, L; Karman, B N; Flaws, J A

    2015-03-01

    The aryl hydrocarbon receptor (AHR) mediates the toxic effects of various endocrine disrupting chemicals. In female mice, global deletion of the Ahr (AhrKO) results in slow growth of ovarian antral follicles. No studies, however, have examined whether injection of the Ahr restores the phenotypes of cultured AhrKO ovarian antral follicles to wild-type levels. We developed a system to construct a recombinant adenovirus containing the Ahr to re-express the Ahr in AhrKO granulosa cells and whole antral follicles. We then compared follicle growth and levels of factors in the AHR signaling pathway (Ahr, Ahrr, Cyp1a1, and Cyp1b1) in wild-type, AhrKO, and Ahr re-expressed follicles. Further, we compared the response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in wild-type, AhrKO, and Ahr re-expressed follicles. Ahr injection into AhrKO follicles partially restored their growth pattern to wild-type levels. Further, Ahr re-expressed follicles had significantly higher levels of Ahr, Ahrr, Cyp1a1, and Cyp1b1 compared to wild-type follicles. Upon TCDD treatment, only Cyp1a1 levels were significantly higher in Ahr re-expressed follicles compared to the levels in wild-type follicles. Our system of re-expression of the Ahr partially restores follicle growth and transcript levels of factors in the AHR signaling pathway to wild-type levels. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Bidirectional communication between the Aryl hydrocarbon Receptor (AhR) and the microbiome tunes host metabolism.

    PubMed

    Korecka, Agata; Dona, Anthony; Lahiri, Shawon; Tett, Adrian James; Al-Asmakh, Maha; Braniste, Viorica; D'Arienzo, Rossana; Abbaspour, Afrouz; Reichardt, Nicole; Fujii-Kuriyama, Yoshiaki; Rafter, Joseph; Narbad, Arjan; Holmes, Elaine; Nicholson, Jeremy; Arulampalam, Velmurugesan; Pettersson, Sven

    2016-01-01

    The ligand-induced transcription factor, aryl hydrocarbon receptor (AhR) is known for its capacity to tune adaptive immunity and xenobiotic metabolism-biological properties subject to regulation by the indigenous microbiome. The objective of this study was to probe the postulated microbiome-AhR crosstalk and whether such an axis could influence metabolic homeostasis of the host. Utilising a systems-biology approach combining in-depth 1 H-NMR-based metabonomics (plasma, liver and skeletal muscle) with microbiome profiling (small intestine, colon and faeces) of AhR knockout (AhR -/- ) and wild-type (AhR +/+ ) mice, we assessed AhR function in host metabolism. Microbiome metabolites such as short-chain fatty acids were found to regulate AhR and its target genes in liver and intestine. The AhR signalling pathway, in turn, was able to influence microbiome composition in the small intestine as evident from microbiota profiling of the AhR +/+ and AhR -/- mice fed with diet enriched with a specific AhR ligand or diet depleted of any known AhR ligands. The AhR -/- mice also displayed increased levels of corticosterol and alanine in serum. In addition, activation of gluconeogenic genes in the AhR -/- mice was indicative of on-going metabolic stress. Reduced levels of ketone bodies and reduced expression of genes involved in fatty acid metabolism in the liver further underscored this observation. Interestingly, exposing AhR -/- mice to a high-fat diet showed resilience to glucose intolerance. Our data suggest the existence of a bidirectional AhR-microbiome axis, which influences host metabolic pathways.

  13. The anticonvulsant action of AHR-11748 on kindled amygdaloid seizures in rats.

    PubMed

    Albertson, T E; Walby, W F

    1987-03-01

    The anticonvulsant effectiveness of AHR-11748 (3-[3-(trifluoromethyl)phenoxy]-1-azetidinecarboxamide) was evaluated in the kindled amygdaloid seizure model in rats. Doses of AHR-11748 that did not cause prestimulation toxicity significantly attenuated elicited afterdischarge durations and the severity of the accompanying behavioral convulsive response in previously kindled rats. AHR-11748 (25-100 mg/kg i.p.) was evaluated at 30 min in previously kindled rats using both threshold (20 microA increments) and suprathreshold (400 microA) paradigms. AHR-11748 (50-100.mg/kg) reduced suprathreshold elicited after discharges and seizure severity. Utilizing a suprathreshold kindling paradigm, the maximum anticonvulsant effectiveness for the 100 mg/kg i.p. dose of AHR-11748 was seen at 180 min. AHR-11748 significantly elevated seizure thresholds only at the 100 mg/kg dose. AHR-11748 (25-100 mg/kg) significantly reduced the severity of threshold elicited seizures. When AHR-11748 (50 and 100 mg/kg i.p.) was administered daily during kindling acquisition, the number of daily trials necessary to complete kindling significantly increased. A reduction in both the duration and the severity of the responses induced by the daily stimulations during the acquisition period was seen with AHR-11748 treatment. This study has demonstrated that AHR-11748 significantly modifies both the acquisition of kindling and the fully kindled amygdaloid seizures at doses that do not cause behavioral toxicity.

  14. Aryl hydrocarbon receptor (AHR) in the cnidarian Nematostella vectensis: comparative expression, protein interactions, and ligand binding.

    PubMed

    Reitzel, Adam M; Passamaneck, Yale J; Karchner, Sibel I; Franks, Diana G; Martindale, Mark Q; Tarrant, Ann M; Hahn, Mark E

    2014-02-01

    The aryl hydrocarbon receptor (AHR) is a member of the basic helix-loop-helix/Per-ARNT-Sim (bHLH-PAS) family of transcription factors and has diverse roles in development, physiology, and environmental sensing in bilaterian animals. Studying the expression of conserved genes and function of proteins in outgroups to protostomes and deuterostomes assists in understanding the antiquity of gene function and deciphering lineage-specific differences in these bilaterian clades. We describe the developmental expression of AHR from the sea anemone Nematostella vectensis and compare its expression with three other members of the bHLH-PAS family (AHR nuclear translocator (ARNT), Cycle, and a proto-Single-Minded/Trachealess). NvAHR expression was highest early in the larval stage with spatial expression in the basal portion of the ectoderm that became increasingly restricted to the oral pole with concentrated expression in tentacles of the juvenile polyp. The other bHLH-PAS genes showed a divergent expression pattern in later larval stages and polyps, in which gene expression was concentrated in the aboral end, with broader expression in the endoderm later in development. In co-immunoprecipitation assays, we found no evidence for heterodimerization of AHR with ARNT, contrary to the conservation of this specific interaction in all bilaterians studied to date. Similar to results with other invertebrate AHRs but in contrast to vertebrate AHRs, NvAHR failed to bind two prototypical xenobiotic AHR ligands (2,3,7,8-tetrachlorodibenzo-p-dioxin, β-naphthoflavone). Together, our data suggest that AHR's original function in Eumetazoa likely involved developmental patterning, potentially of neural tissue. The role of heterodimerization in the function of AHR may have arisen after the cnidarian-bilaterian ancestor. The absence of xenobiotic binding to NvAHR further supports a hypothesis for a derived role of this protein in chemical sensing within the chordates.

  15. Aryl hydrocarbon receptor (AHR) in the cnidarian Nematostella vectensis: comparative expression, protein interactions, and ligand binding

    PubMed Central

    Reitzel, Adam M.; Passamaneck, Yale J.; Karchner, Sibel I.; Franks, Diana G.; Martindale, Mark Q.; Tarrant, Ann M.; Hahn, Mark E.

    2014-01-01

    The aryl hydrocarbon receptor (AHR) is a member of the basic-helix-loop-helix/Per-ARNT-Sim (bHLH-PAS) family of transcription factors and has diverse roles in development, physiology, and environmental sensing in bilaterian animals. Studying the expression of conserved genes and function of proteins in outgroups to protostomes and deuterostomes assists in understanding the antiquity of gene function and deciphering lineage-specific differences in these bilaterian clades. We describe the developmental expression of AHR from the sea anemone Nematostella vectensis and compare its expression with three other members of the bHLH-PAS family (AHR nuclear translocator (ARNT), Cycle, and a proto-Single-Minded/Trachaeless). NvAHR expression was highest early in the larval stage with spatial expression in the basal portion of the ectoderm that became increasingly restricted to the oral pole with concentrated expression in tentacles of the juvenile polyp. The other bHLH-PAS genes showed a divergent expression pattern in later larval stages and polyps, in which gene expression was concentrated in the aboral end, with broader expression in the endoderm later in development. In co-immunoprecipitation assays, we found no evidence for heterodimerization of AHR with ARNT, contrary to the conservation of this specific interaction in all bilaterians studied to date. Similar to results with other invertebrate AHRs but in contrast to vertebrate AHRs, NvAHR failed to bind two prototypical xenobiotic AHR ligands (TCDD, BNF). Together, our data suggest that AHR's original function in Eumetazoa likely involved developmental patterning, potentially of neural tissue. The role of heterodimerization in the function of AHR may have arisen after the cnidarian-bilaterian ancestor. The absence of xenobiotic binding to NvAHR further supports a hypothesis for a derived role of this protein in chemical sensing within the chordates. PMID:24292160

  16. Structural hierarchy controlling dimerization and target DNA recognition in the AHR transcriptional complex.

    PubMed

    Seok, Seung-Hyeon; Lee, Woojong; Jiang, Li; Molugu, Kaivalya; Zheng, Aiping; Li, Yitong; Park, Sanghyun; Bradfield, Christopher A; Xing, Yongna

    2017-05-23

    The aryl hydrocarbon receptor (AHR) belongs to the PAS (PER-ARNT-SIM) family transcription factors and mediates broad responses to numerous environmental pollutants and cellular metabolites, modulating diverse biological processes from adaptive metabolism, acute toxicity, to normal physiology of vascular and immune systems. The AHR forms a transcriptionally active heterodimer with ARNT (AHR nuclear translocator), which recognizes the dioxin response element (DRE) in the promoter of downstream genes. We determined the crystal structure of the mammalian AHR-ARNT heterodimer in complex with the DRE, in which ARNT curls around AHR into a highly intertwined asymmetric architecture, with extensive heterodimerization interfaces and AHR interdomain interactions. Specific recognition of the DRE is determined locally by the DNA-binding residues, which discriminates it from the closely related hypoxia response element (HRE), and is globally affected by the dimerization interfaces and interdomain interactions. Changes at the interdomain interactions caused either AHR constitutive nuclear localization or failure to translocate to nucleus, underlying an allosteric structural pathway for mediating ligand-induced exposure of nuclear localization signal. These observations, together with the global higher flexibility of the AHR PAS-A and its loosely packed structural elements, suggest a dynamic structural hierarchy for complex scenarios of AHR activation induced by its diverse ligands.

  17. Potential involvement of placental AhR in unexplained recurrent spontaneous abortion.

    PubMed

    Wu, Y; Chen, X; Chang, X; Huang, Y J; Bao, S; He, Q; Li, Y; Zheng, J; Duan, T; Wang, K

    2016-01-01

    Recurrent spontaneous abortion (RSA) is a common complication of pregnancy. Recent studies have demonstrated that the aryl hydrocarbon receptor (AhR) might play important roles in establishing and maintaining early pregnancy. In this study, we found that placental AhR protein levels were significantly lower and placental CYP1A1 mRNA levels were higher in unexplained RSA (URSA) patients than in control subjects. The results of immunohistochemical analyzes showed that placental AhR was expressed in syncytiotrophoblast cells and that the level of AhR was markedly lower in these cells in URSA subjects than in control subjects. β-Naphthoflavone (β-NF, an AhR ligand) at 5μM significantly inhibited proliferation and migration in HTR-8/SVneo cells and was associated with the activation of AhR. Moreover, overexpressing AhR in JAR cells significantly increased CYP1A1 mRNA levels and inhibited cell migration. These results indicate that AhR is highly activated in URSA placentas and that the activation of AhR in the placenta might impair trophoblast cell proliferation and migration, possibly leading to the occurrence of URSA. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. 75 FR 49550 - Fifth Meeting: RTCA Special Committee 219: Attitude and Heading Reference System (AHRS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-13

    ... 219: Attitude and Heading Reference System (AHRS) AGENCY: Federal Aviation Administration (FAA), Department of Transportation (DOT). ACTION: Notice of RTCA Special Committee 219: Attitude and Heading... 49551

  19. Combination effects of AHR agonists and Wnt/β-catenin modulators in zebrafish embryos: Implications for physiological and toxicological AHR functions

    SciTech Connect

    Wincent, Emma; Institute of Environmental Medicine, Karolinska Institutet, 17177 Stockholm; Stegeman, John J.

    2015-04-15

    Wnt/β-catenin signaling regulates essential biological functions and acts in developmental toxicity of some chemicals. The aryl hydrocarbon receptor (AHR) is well-known to mediate developmental toxicity of persistent dioxin-like compounds (DLCs). Recent studies indicate a crosstalk between β-catenin and the AHR in some tissues. However the nature of this crosstalk in embryos is poorly known. We observed that zebrafish embryos exposed to the β-catenin inhibitor XAV939 display effects phenocopying those of the dioxin-like 3,3′,4,4′,5-pentachlorobiphenyl (PCB126). This led us to investigate the AHR interaction with β-catenin during development and ask whether developmental toxicity of DLCs involves antagonism of β-catenin signaling. We examinedmore » phenotypes and transcriptional responses in zebrafish embryos exposed to XAV939 or to a β-catenin activator, 1-azakenpaullone, alone or with AHR agonists, either PCB126 or 6-formylindolo[3,2-b]carbazole (FICZ). Alone 1-azakenpaullone and XAV939 both were embryo-toxic, and we found that in the presence of FICZ, the toxicity of 1-azakenpaullone decreased while the toxicity of XAV939 increased. This rescue of 1-azakenpaullone effects occurred in the time window of Ahr2-mediated toxicity and was reversed by morpholino-oligonucleotide knockdown of Ahr2. Regarding PCB126, addition of either 1-azakenpaullone or XAV939 led to lower mortality than with PCB126 alone but surviving embryos showed severe edemas. 1-Azakenpaullone induced transcription of β-catenin-associated genes, while PCB126 and FICZ blocked this induction. The data indicate a stage-dependent antagonism of β-catenin by Ahr2 in zebrafish embryos. We propose that the AHR has a physiological role in regulating β-catenin during development, and that this is one point of intersection linking toxicological and physiological AHR-governed processes.« less

  20. Aryl Hydrocarbon Receptor (AhR) Deletion in Cerebellar Granule Neuron Precursors Impairs Neurogenesis

    PubMed Central

    Dever, Daniel P.; Adham, Zachariah O.; Thompson, Bryan; Genestine, Matthieu; Cherry, Jonathan; Olschowka, John A.; DiCicco-Bloom, Emanuel; Opanashuk, Lisa A.

    2015-01-01

    The aryl hydrocarbon receptor (AhR) is a ligand-activated member of the basic-helix-loop-helix (bHLH)/PER-ARNT-SIM(PAS) transcription factor superfamily that also mediates the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Increasing evidence suggests that AhR influences the development of many tissues, including the central nervous system. Our previous studies suggest that sustained AhR activation by TCDD and/or AhR deletion disrupts cerebellar granule neuron precursor (GNP) development. In the current study, to determine whether endogenous AhR controls GNP development in a cell autonomous manner, we created a GNP-specific AhR deletion mouse, AhRfx/fx/Math1CRE/+ (AhR CKO). Selective AhR deletion in GNPs produced abnormalities in proliferation and differentiation. Specifically, fewer GNPs were engaged in S-phase, as demonstrated by ~25% reductions in thymidine (in vitro) and BrdU (in vivo) incorporation. Furthermore, total granule neuron numbers in the IGL at PND21 and PND60 were diminished in AhR CKO mice compared to controls. On the other hand, differentiation was enhanced, including ~40% increase in neurite outgrowth and 50% increase in GABARα6 receptor expression in deletion mutants. Our results suggest that AhR activity plays a role in regulating granule neuron number and differentiation, possibly by coordinating this GNP developmental transition. These studies provide novel insights for understanding the normal roles of AhR signaling during cerebellar granule cell neurogenesis, and may have important implications for the effects of environmental factors in cerebellar dysgenesis. PMID:26243376

  1. Cytokine responses induced by diesel exhaust particles are suppressed by PAR-2 silencing and antioxidant treatment, and driven by polar and non-polar soluble constituents.

    PubMed

    Bach, Nicolai; Bølling, Anette Kocbach; Brinchmann, Bendik C; Totlandsdal, Annike I; Skuland, Tonje; Holme, Jørn A; Låg, Marit; Schwarze, Per E; Øvrevik, Johan

    2015-10-14

    Adsorbed soluble organics seem to be the main drivers of inflammatory responses induced by diesel exhaust particles (DEP). The specific compounds contributing to this process and the cellular mechanisms behind DEP-induced inflammation are not well known. We have assessed pro-inflammatory effects of DEP and various soluble DEP fractions, in human bronchial epithelial cells (BEAS-2B). DEP increased the expression of interleukin (IL)-6 and CXCL8. Silencing of the aryl hydrocarbon receptor (AhR) by siRNA or pretreatment with AhR-antagonists did not attenuate DEP-induced IL-6 and CXCL8 responses. However, the halogenated aromatic hydrocarbon (HAH)-selective AhR antagonist CH223191 caused a considerable reduction in DEP-induced CYP1A1 expression indicating that this response may be due to dioxin or dioxin-like constituents in DEP. Knock-down of protease activated receptor (PAR)-2 attenuated IL-6 responses without affecting CXCL8. Antioxidants did not affect IL-6 expression after 4h DEP-exposure and only partly reduced CXCL8 expression. However, after 24h exposure antioxidant treatment partly suppressed IL-6 protein release and completely blocked CXCL8 release. Furthermore, a heptane-soluble (non-polar) extract of DEP induced both IL-6 and CXCL8 release, whereas a PBS-soluble (highly polar) extract induced only IL-6. Thus, pro-inflammatory responses in DEP-exposed epithelial cells appear to be the result of both reactive oxygen species and receptor signaling, mediated through combinatorial effects between both non-polar and polar constituents adhered to the particle surface. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  2. Micro124-mediated AHR expression regulates the inflammatory response of chronic rhinosinusitis (CRS) with nasal polyps.

    PubMed

    Liu, C C; Xia, M; Zhang, Y J; Jin, P; Zhao, L; Zhang, J; Li, T; Zhou, X M; Tu, Y Y; Kong, F; Sun, C; Shi, L; Zhao, M Q

    2018-06-02

    MicroRNAs represent a component of the innate immune responses that can restrain inflammatory signaling, miR124 is an important member of inflammation-associated miRNAs, and abnormal miR124 expression is observed in many inflammatory diseases and immune disorders. However, the role and signaling pathways of miR124 in chronic rhinosinusitis with nasal polyps (CRSwNPs) have not been studied in detail. The aryl hydrocarbon receptor (AHR) is a ligand-inducible transcription factor that is highly conserved in evolution and plays important roles in the inflammatory response process. In our study, we describe the role of miR124 in the inflammatory response of CRS with nasal polyps. We found that the expression of miR124 was decreased in nasal polyps, and negatively correlated with the expression of AHR. MiR124 can inhibit AHR expression by directly target 3' untranslated region (3'-UTR) of AHR. To further investigate the relationship between miR124, AHR and CRS inflammatory response, we transfect HNEpC cells with miR124 mimic, miR124 inhibitors or siRNA of AHR, then all the results showed that miR124 could regulates cellular inflammatory response through negatively regulating AHR expression. This study demonstrated that the regulation of AHR expression by miR124 is critical to the development of inflammatory response in CRSwNPs. Copyright © 2018. Published by Elsevier Inc.

  3. Macrophages from Behcet's Disease Patients Express Decreased Level of Aryl Hydrocarbon Receptor (AHR) mRNA.

    PubMed

    Palizgir, Mohammad Taghi; Akhtari, Maryam; Mahmoudi, Mahdi; Mostafaei, Shayan; Rezaeimanesh, Alireza; Akhlaghi, Massoomeh; Shahram, Farhad

    2017-10-01

    Aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor, connecting environmental stimulators with the immune system. M1 macrophages are a part of immune system that contribute to the inflammatory events in the pathogenesis of Behcet's disease (BD). The effect of AHR on the macrophages in BD patients is still unclear. In this study, we investigated the mRNA expression of AHR in the monocyte-derived and M1 macrophages in active BD patients in comparison to healthy controls. Isolated monocytes from 10 healthy controls and 10 active BD patients were differentiated to macrophages by macrophage-colony stimulating factor (M-CSF) for 7 days. Cells were then polarized to M1 macrophages by lipopolysaccharide (LPS) and interferon-γ (IFNγ) for 24h. Monocyte purity and macrophage markers expression were analyzed by flow cytometry. Analysis of AHR mRNA expression was performed by SYBR Green real-time PCR. Our results showed that AHR expression is significantly down-regulated in M1 macrophages compare to monocyte-derived macrophages. It was shown that both monocyte-derived macrophages and M1 macrophages from BD patients significantly express lower level of AHR mRNA compared to healthy individuals. Our results demonstrate an anti-inflammatory role for AHR in macrophages, which suggest that decreased AHR expression is associated with pro-inflammatory M1 macrophage and BD susceptibility.

  4. Structural hierarchy controlling dimerization and target DNA recognition in the AHR transcriptional complex

    PubMed Central

    Lee, Woojong; Jiang, Li; Molugu, Kaivalya; Zheng, Aiping; Li, Yitong; Park, Sanghyun; Bradfield, Christopher A.; Xing, Yongna

    2017-01-01

    The aryl hydrocarbon receptor (AHR) belongs to the PAS (PER-ARNT-SIM) family transcription factors and mediates broad responses to numerous environmental pollutants and cellular metabolites, modulating diverse biological processes from adaptive metabolism, acute toxicity, to normal physiology of vascular and immune systems. The AHR forms a transcriptionally active heterodimer with ARNT (AHR nuclear translocator), which recognizes the dioxin response element (DRE) in the promoter of downstream genes. We determined the crystal structure of the mammalian AHR–ARNT heterodimer in complex with the DRE, in which ARNT curls around AHR into a highly intertwined asymmetric architecture, with extensive heterodimerization interfaces and AHR interdomain interactions. Specific recognition of the DRE is determined locally by the DNA-binding residues, which discriminates it from the closely related hypoxia response element (HRE), and is globally affected by the dimerization interfaces and interdomain interactions. Changes at the interdomain interactions caused either AHR constitutive nuclear localization or failure to translocate to nucleus, underlying an allosteric structural pathway for mediating ligand-induced exposure of nuclear localization signal. These observations, together with the global higher flexibility of the AHR PAS-A and its loosely packed structural elements, suggest a dynamic structural hierarchy for complex scenarios of AHR activation induced by its diverse ligands. PMID:28396409

  5. Use of natural AhR ligands as potential therapeutic modalities against inflammatory disorders

    PubMed Central

    Busbee, Philip B; Rouse, Michael; Nagarkatti, Mitzi; Nagarkatti, Prakash S

    2014-01-01

    The aim of this review is to discuss research involving ligands for the aryl hydrocarbon receptor (AhR) and their role in immunomodulation. While activation of the AhR is well known for its ability to regulate the biochemical and toxic effects of environmental chemicals, more recently an exciting discovery has been made indicating that AhR ligation can also regulate T-cell differentiation, specifically through activation of Foxp3+ regulatory T cells (Tregs) and downregulation of the proinflammatory Th17 cells. Such findings have opened new avenues of research on the possibility of targeting the AhR to treat inflammatory and autoimmune diseases. Specifically, this review will discuss the current research involving natural and dietary AhR ligands. In addition, evidence indicating the potential use of these ligands in regulating inflammation in various diseases will be highlighted. The importance of the AhR in immunological processes can be illustrated by expression of this receptor on a majority of immune cell types. In addition, AhR signaling pathways have been reported to influence a number of genes responsible for mediating inflammation and other immune responses. As interest in the AhR and its ligands increases, it seems prudent to consolidate current research on the contributions of these ligands to immune regulation during the course of inflammatory diseases. PMID:23731446

  6. Structural hierarchy controlling dimerization and target DNA recognition in the AHR transcriptional complex

    SciTech Connect

    Seok, Seung-Hyeon; Lee, Woojong; Jiang, Li

    he aryl hydrocarbon receptor (AHR) belongs to the PAS (PER-ARNT-SIM) family transcription factors and mediates broad responses to numerous environmental pollutants and cellular metabolites, modulating diverse biological processes from adaptive metabolism, acute toxicity, to normal physiology of vascular and immune systems. The AHR forms a transcriptionally active heterodimer with ARNT (AHR nuclear translocator), which recognizes the dioxin response element (DRE) in the promoter of downstream genes. We determined the crystal structure of the mammalian AHR–ARNT heterodimer in complex with the DRE, in which ARNT curls around AHR into a highly intertwined asymmetric architecture, with extensive heterodimerization interfaces and AHR interdomainmore » interactions. Specific recognition of the DRE is determined locally by the DNA-binding residues, which discriminates it from the closely related hypoxia response element (HRE), and is globally affected by the dimerization interfaces and interdomain interactions. Changes at the interdomain interactions caused either AHR constitutive nuclear localization or failure to translocate to nucleus, underlying an allosteric structural pathway for mediating ligand-induced exposure of nuclear localization signal. These observations, together with the global higher flexibility of the AHR PAS-A and its loosely packed structural elements, suggest a dynamic structural hierarchy for complex scenarios of AHR activation induced by its diverse ligands.« less

  7. 76 FR 80447 - Eighth Meeting: RTCA Special Committee 219: Attitude and Heading Reference Systems (AHRS)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-23

    ... Committee 219: Attitude and Heading Reference Systems (AHRS) AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Notice of RTCA Special Committee 219: Attitude and... eighth meeting of RTCA Special Committee 219: Attitude and Heading Reference Systems (AHRS). DATES: The...

  8. Serotonin is an endogenous regulator of intestinal CYP1A1 via AhR.

    PubMed

    Manzella, Christopher; Singhal, Megha; Alrefai, Waddah A; Saksena, Seema; Dudeja, Pradeep K; Gill, Ravinder K

    2018-04-17

    Aryl hydrocarbon receptor (AhR) is a nuclear receptor that controls xenobiotic detoxification via induction of cytochrome P450 1A1 (CYP1A1) and regulates immune responses in the intestine. Metabolites of L-tryptophan activate AhR, which confers protection against intestinal inflammation. We tested the hypothesis that serotonin (5-HT) is an endogenous activator of AhR in intestinal epithelial cells. Treatment of Caco-2 monolayers with 5-HT induced CYP1A1 mRNA in a time- and concentration-dependent manner and also stimulated CYP1A1 activity. CYP1A1 induction by 5-HT was dependent upon uptake via serotonin transporter (SERT). Antagonism of AhR and knockdown of AhR and its binding partner aryl hydrocarbon receptor nuclear translocator (ARNT) attenuated CYP1A1 induction by 5-HT. Activation of AhR was evident by its nuclear translocation after 5-HT treatment and by induction of an AhR-responsive luciferase reporter. In vivo studies showed a dramatic decrease in CYP1A1 expression and other AhR target genes in SERT KO ileal mucosa by microarray analysis. These results suggest that intracellular accumulation of 5-HT via SERT induces CYP1A1 expression via AhR in intestinal epithelial cells, and SERT deficiency in vivo impairs activation of AhR. Our studies provide a novel link between the serotonergic and AhR pathways which has implications in xenobiotic metabolism and intestinal inflammation.

  9. Overexpression of aryl hydrocarbon receptor (AHR) signalling pathway in human meningioma.

    PubMed

    Talari, Noble Kumar; Panigrahi, Manas K; Madigubba, Sailaja; Phanithi, Prakash Babu

    2018-04-01

    Aryl hydrocarbon receptor (AHR) is a ligand activated transcription factor and involved in tumorigenesis of many cancers. However there are no reports on AHR in human meningioma. Therefore we examined the status of the AHR and its signalling molecules in human meningioma by using tumor biopsy samples and autopsy control meninges. We report the up regulation of AHR pathway genes like aryl hydrocarbon receptor nuclear translocator (ARNT), aldehyde dehydrogenase1family memberA3 (ALDH1A3), cytochrome P450, family1, subfamily A polypeptide1 (CYP1A1) and TCCD induced poly ADP ribose polymerase (TIPARP) gene expression in human meningioma. Further, AHR protein expression was found to be up regulated in all grades of human meningioma. We found that AHR localized in the nucleus for high grade anaplastic meningioma through immunohistochemical analysis. Since AHR signalling pathway was known to involve in inhibition of apoptosis in cancer cells, we evaluated the cyclophilin D levels which maintains mitochondrial permeability transition pore a critical event during apoptosis. We report that cyclophilin D levels were upregulated in all grades of human meningioma compared to control meninges. Finally we also evaluated c-Fos protein levels as its levels were regulated by AHR. Here we report that c-Fos protein levels were down regulated in all grades of human meningioma compared to control meninges. To sum-up we found that AHR signalling pathway components were upregulated, as the grade of the meningioma progresses from low to high grade, suggesting an important role of AHR signalling pathway in human meningioma.

  10. Simultaneous inhibition of aryl hydrocarbon receptor (AhR) and Src abolishes androgen receptor signaling.

    PubMed

    Ghotbaddini, Maryam; Cisse, Keyana; Carey, Alexis; Powell, Joann B

    2017-01-01

    Altered c-Src activity has been strongly implicated in the development, growth, progression, and metastasis of human cancers including prostate cancer. Src is known to regulate several biological functions of tumor cells, including proliferation. There are several Src inhibitors under evaluation for clinical effectiveness but have shown little activity in monotherapy trials of solid tumors. Combination studies are being explored by in vitro analysis and in clinical trials. Here we investigate the effect of simultaneous inhibition of the aryl hydrocarbon receptor (AhR) and Src on androgen receptor (AR) signaling in prostate cancer cells. AhR has also been reported to interact with the Src signaling pathway during prostate development. c-Src protein kinase is associated with the AhR complex in the cytosol and upon ligand binding to AhR, c-Src is activated and released from the complex. AhR has also been shown to regulate AR signaling which remains functionally important in the development and progression of prostate cancer. We provide evidence that co-inhibition of AhR and Src abolish AR activity. Evaluation of total protein and cellular fractions revealed decreased pAR expression and AR nuclear localization. Assays utilizing an androgen responsive element (ARE) and qRT-PCR analysis of AR genes revealed decreased AR promoter activity and transcriptional activity in the presence of both AhR and Src inhibitors. Furthermore, co-inhibition of AhR and Src reduced the growth of prostate cancer cells compared to individual treatments. Several studies have revealed that AhR and Src individually inhibit cellular proliferation. However, this study is the first to suggest simultaneous inhibition of AhR and Src to inhibit AR signaling and prostate cancer cell growth.

  11. Suppression of CYP1 members of the AHR response by pathogen-associated molecular patterns.

    PubMed

    Peres, Adam G; Zamboni, Robert; King, Irah L; Madrenas, Joaquín

    2017-12-01

    The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that triggers a broad response, which includes the regulation of proinflammatory cytokine production by monocytes and macrophages. AHR is negatively regulated by a set of genes that it transcriptionally activates, including the AHR repressor ( Ahrr ) and the cytochrome P450 1 ( Cyp1 ) family, which are critical for preventing exacerbated AHR activity. An imbalance in these regulatory mechanisms has been shown to cause severe defects in lymphoid cells. Therefore, we wanted to assess how AHR activation is regulated in monocytes and macrophages in the context of innate immune responses induced by pathogen-associated molecular patterns (PAMPs). We found that concomitant stimulation of primary human monocytes with PAMPs and the AHR agonist 6-formylindolo(3,2-b)carbazole (FICZ) led to a selective dose-dependent inhibition of Cyp1 family members induction. Two other AHR-dependent genes [ Ahrr and NADPH quinone dehydrogenase 1 ( Nqo1 )] were not affected under these conditions, suggesting a split in the AHR regulation by PAMPs. This down-regulation of Cyp1 family members did not require de novo protein production nor signaling through p38, ERK, or PI3K-Akt-mammalian target of rapamycin (mTOR) pathways. Furthermore, such a split regulation of the AHR response was more apparent in GM-CSF-derived macrophages, a finding corroborated at the functional level by decreased CYP1 activity and decreased proinflammatory cytokine production in response to FICZ and LPS. Collectively, our findings identify a role for pattern recognition receptor (PRR) signaling in regulating the AHR response through selective down-regulation of Cyp1 expression in human monocytes and macrophages. © Society for Leukocyte Biology.

  12. Accurate Orientation Estimation Using AHRS under Conditions of Magnetic Distortion

    PubMed Central

    Yadav, Nagesh; Bleakley, Chris

    2014-01-01

    Low cost, compact attitude heading reference systems (AHRS) are now being used to track human body movements in indoor environments by estimation of the 3D orientation of body segments. In many of these systems, heading estimation is achieved by monitoring the strength of the Earth's magnetic field. However, the Earth's magnetic field can be locally distorted due to the proximity of ferrous and/or magnetic objects. Herein, we propose a novel method for accurate 3D orientation estimation using an AHRS, comprised of an accelerometer, gyroscope and magnetometer, under conditions of magnetic field distortion. The system performs online detection and compensation for magnetic disturbances, due to, for example, the presence of ferrous objects. The magnetic distortions are detected by exploiting variations in magnetic dip angle, relative to the gravity vector, and in magnetic strength. We investigate and show the advantages of using both magnetic strength and magnetic dip angle for detecting the presence of magnetic distortions. The correction method is based on a particle filter, which performs the correction using an adaptive cost function and by adapting the variance during particle resampling, so as to place more emphasis on the results of dead reckoning of the gyroscope measurements and less on the magnetometer readings. The proposed method was tested in an indoor environment in the presence of various magnetic distortions and under various accelerations (up to 3 g). In the experiments, the proposed algorithm achieves <2° static peak-to-peak error and <5° dynamic peak-to-peak error, significantly outperforming previous methods. PMID:25347584

  13. INSIGHTS FROM AHR AND ARNT GENE KNOCKOUT STUDIES REGARDING RESPONSES TO TCDD AND REGULATION OF NORMAL EMBRYONIC DEVELOPMENT

    EPA Science Inventory

    The aryl hydrocarbon receptor (AhR) and the AhR nuclear translocator (ARNT) are members of the Per-ARNT-Sim (PAS) family of proteins. The AhR binds members of the chemical family that includes dioxins, furans and coplanar polychlorinated biphenyls (PCBs). A ligand-AhR-ARNT comp...

  14. Bidirectional communication between the Aryl hydrocarbon Receptor (AhR) and the microbiome tunes host metabolism

    PubMed Central

    Korecka, Agata; Dona, Anthony; Lahiri, Shawon; Tett, Adrian James; Al-Asmakh, Maha; Braniste, Viorica; D’Arienzo, Rossana; Abbaspour, Afrouz; Reichardt, Nicole; Fujii-Kuriyama, Yoshiaki; Rafter, Joseph; Narbad, Arjan; Holmes, Elaine; Nicholson, Jeremy; Arulampalam, Velmurugesan; Pettersson, Sven

    2016-01-01

    The ligand-induced transcription factor, aryl hydrocarbon receptor (AhR) is known for its capacity to tune adaptive immunity and xenobiotic metabolism—biological properties subject to regulation by the indigenous microbiome. The objective of this study was to probe the postulated microbiome-AhR crosstalk and whether such an axis could influence metabolic homeostasis of the host. Utilising a systems-biology approach combining in-depth 1H-NMR-based metabonomics (plasma, liver and skeletal muscle) with microbiome profiling (small intestine, colon and faeces) of AhR knockout (AhR−/−) and wild-type (AhR+/+) mice, we assessed AhR function in host metabolism. Microbiome metabolites such as short-chain fatty acids were found to regulate AhR and its target genes in liver and intestine. The AhR signalling pathway, in turn, was able to influence microbiome composition in the small intestine as evident from microbiota profiling of the AhR+/+ and AhR−/− mice fed with diet enriched with a specific AhR ligand or diet depleted of any known AhR ligands. The AhR−/− mice also displayed increased levels of corticosterol and alanine in serum. In addition, activation of gluconeogenic genes in the AhR−/− mice was indicative of on-going metabolic stress. Reduced levels of ketone bodies and reduced expression of genes involved in fatty acid metabolism in the liver further underscored this observation. Interestingly, exposing AhR−/− mice to a high-fat diet showed resilience to glucose intolerance. Our data suggest the existence of a bidirectional AhR-microbiome axis, which influences host metabolic pathways. PMID:28721249

  15. Aryl hydrocarbon receptor (AHR) is a potential tumour suppressor in pituitary adenomas.

    PubMed

    Formosa, R; Borg, J; Vassallo, J

    2017-08-01

    Pituitary adenomas (PA) represent the largest group of intracranial neoplasms and yet the molecular mechanisms driving this disease remain largely unknown. The aim of this study was to use a high-throughput screening method to identify molecular pathways that may be playing a significant and consistent role in PA. RNA profiling using microarrays on eight local PAs identified the aryl hydrocarbon receptor (AHR) signalling pathway as a key canonical pathway downregulated in all PA types. This was confirmed by real-time PCR in 31 tumours. The AHR has been shown to regulate cell cycle progression in various cell types; however, its role in pituitary tissue has never been investigated. In order to validate the role of AHR in PA behaviour, further functional studies were undertaken. Over-expression of AHR in GH3 cells revealed a tumour suppressor potential independent of exogenous ligand activation by benzo α-pyrene (BαP). Cell cycle analysis and quantitative PCR of cell cycle regulator genes revealed that both unstimulated and BαP-stimulated AHR reduced E2F-driven transcription and altered expression of cell cycle regulator genes, thus increasing the percentage of cells in G 0 /G 1 phase and slowing the proliferation rate of GH3 cells. Co-immunoprecipitation confirmed the interaction between AHR and retinoblastoma (Rb1) protein supporting this as a functional mechanism for the observed reduction. Endogenous Ahr reduction using silencing RNA confirmed the tumour suppressive function of the Ahr. These data support a mechanistic pathway for the putative tumour suppressive role of AHR specifically in PA, possibly through its role as a cell cycle co-regulator, even in the absence of exogenous ligands. © 2017 The authors.

  16. Aryl hydrocarbon receptor (AHR) is a potential tumour suppressor in pituitary adenomas

    PubMed Central

    Formosa, R; Borg, J

    2017-01-01

    Pituitary adenomas (PA) represent the largest group of intracranial neoplasms and yet the molecular mechanisms driving this disease remain largely unknown. The aim of this study was to use a high-throughput screening method to identify molecular pathways that may be playing a significant and consistent role in PA. RNA profiling using microarrays on eight local PAs identified the aryl hydrocarbon receptor (AHR) signalling pathway as a key canonical pathway downregulated in all PA types. This was confirmed by real-time PCR in 31 tumours. The AHR has been shown to regulate cell cycle progression in various cell types; however, its role in pituitary tissue has never been investigated. In order to validate the role of AHR in PA behaviour, further functional studies were undertaken. Over-expression of AHR in GH3 cells revealed a tumour suppressor potential independent of exogenous ligand activation by benzo α-pyrene (BαP). Cell cycle analysis and quantitative PCR of cell cycle regulator genes revealed that both unstimulated and BαP-stimulated AHR reduced E2F-driven transcription and altered expression of cell cycle regulator genes, thus increasing the percentage of cells in G0/G1 phase and slowing the proliferation rate of GH3 cells. Co-immunoprecipitation confirmed the interaction between AHR and retinoblastoma (Rb1) protein supporting this as a functional mechanism for the observed reduction. Endogenous Ahr reduction using silencing RNA confirmed the tumour suppressive function of the Ahr. These data support a mechanistic pathway for the putative tumour suppressive role of AHR specifically in PA, possibly through its role as a cell cycle co-regulator, even in the absence of exogenous ligands. PMID:28649092

  17. Constitutive expression of the AHR signaling pathway in a bovine mammary epithelial cell line and modulation by dioxin-like PCB and other AHR ligands.

    PubMed

    Girolami, Flavia; Spalenza, Veronica; Manzini, Livio; Carletti, Monica; Nebbia, Carlo

    2015-01-05

    Environmental pollutants, such as dioxin-like (DL) PCBs, benzo(a) pyrene (B[a]P), and flavonoids are aryl hydrocarbon receptor (AHR) ligands and may be excreted in dairy milk. The expression of AHR-target genes, particularly those involved in xenobiotic biotransformation, and their modulation by two DL-PCBs, B[a]P, and β-naphthoflavone was investigated in a bovine mammary epithelial cell line (BME-UV). As assessed by quantitative PCR, BME-UV cells expressed a functional AHR signaling pathway. All the AHR ligands induced a concentration-related increase in the transcription of cytochrome P450 1A1 and 1B1, known to be implicated in the bioactivation of several xenobiotics. Conversely, genes encoding for antioxidant and detoxifying enzymes, like quinone oxidoreductase or glutathione S-transferase A2, were not affected or even depressed. This study demonstrates the occurrence and the modulation by different AHR-ligands of genes involved in xenobiotic metabolism in BME-UV cells, with the potential generation of (re) active metabolites that may damage mammary tissue and/or affect animal or human health via the contaminated milk. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  18. Estimation of weekly 99Mo production by AHR 200 kW

    NASA Astrophysics Data System (ADS)

    Siregar, I. H.; Suharyana; Khakim, A.; Siregar, D.; Frida, A. R.

    2016-11-01

    The estimation of weekly 99Mo production by AHR 200 kW fueled with Low Enriched Uranium Uranyl Nitrate solution has been simulated by using MCNPX computer code. We have employed the AHR design of Babcock & Wilcox Medical Isotope Production System with 9Be Reflector and Stainless steel vessel. We found that when the concentration of uranium in the fresh fuel was 108 gr U/L of UO2(NO3)2 fuel solution, the multiplication factor was 1.0517. The 99Mo concentration reached saturated at tenth day operation. The AHR can produce approximately 1.96×103 6-day-Ci weekly.

  19. Increasing kynurenine brain levels reduces ethanol consumption in mice by inhibiting dopamine release in nucleus accumbens.

    PubMed

    Giménez-Gómez, Pablo; Pérez-Hernández, Mercedes; Gutiérrez-López, María Dolores; Vidal, Rebeca; Abuin-Martínez, Cristina; O'Shea, Esther; Colado, María Isabel

    2018-06-01

    Recent research suggests that ethanol (EtOH) consumption behaviour can be regulated by modifying the kynurenine (KYN) pathway, although the mechanisms involved have not yet been well elucidated. To further explore the implication of the kynurenine pathway in EtOH consumption we inhibited kynurenine 3-monooxygenase (KMO) activity with Ro 61-8048 (100 mg/kg, i.p.), which shifts the KYN metabolic pathway towards kynurenic acid (KYNA) production. KMO inhibition decreases voluntary binge EtOH consumption and EtOH preference in mice subjected to "drinking in the dark" (DID) and "two-bottle choice" paradigms, respectively. This effect seems to be a consequence of increased KYN concentration, since systemic KYN administration (100 mg/kg, i.p.) similarly deters binge EtOH consumption in the DID model. Despite KYN and KYNA being well-established ligands of the aryl hydrocarbon receptor (AhR), administration of AhR antagonists (TMF 5 mg/kg and CH-223191 20 mg/kg, i.p.) and of an agonist (TCDD 50 μg/kg, intragastric) demonstrates that signalling through this receptor is not involved in EtOH consumption behaviour. Ro 61-8048 did not alter plasma acetaldehyde concentration, but prevented EtOH-induced dopamine release in the nucleus accumbens shell. These results point to a critical involvement of the reward circuitry in the reduction of EtOH consumption induced by KYN and KYNA increments. PNU-120596 (3 mg/kg, i.p.), a positive allosteric modulator of α7-nicotinic acetylcholine receptors, partially prevented the Ro 61-8048-induced decrease in EtOH consumption. Overall, our results highlight the usefulness of manipulating the KYN pathway as a pharmacological tool for modifying EtOH consumption and point to a possible modulator of alcohol drinking behaviour. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. The aryl hydrocarbon receptor AhR links atopic dermatitis and air pollution via induction of the neurotrophic factor artemin.

    PubMed

    Hidaka, Takanori; Ogawa, Eisaku; Kobayashi, Eri H; Suzuki, Takafumi; Funayama, Ryo; Nagashima, Takeshi; Fujimura, Taku; Aiba, Setsuya; Nakayama, Keiko; Okuyama, Ryuhei; Yamamoto, Masayuki

    2017-01-01

    Atopic dermatitis is increasing worldwide in correlation with air pollution. Various organic components of pollutants activate the transcription factor AhR (aryl hydrocarbon receptor). Through the use of AhR-CA mice, whose keratinocytes express constitutively active AhR and that develop atopic-dermatitis-like phenotypes, we identified Artn as a keratinocyte-specific AhR target gene whose product (the neurotrophic factor artemin) was responsible for epidermal hyper-innervation that led to hypersensitivity to pruritus. The activation of AhR via air pollutants induced expression of artemin, alloknesis, epidermal hyper-innervation and inflammation. AhR activation and ARTN expression were positively correlated in the epidermis of patients with atopic dermatitis. Thus, AhR in keratinocytes senses environmental stimuli and elicits an atopic-dermatitis pathology. We propose a mechanism of air-pollution-induced atopic dermatitis via activation of AhR.

  1. Aryl hydrocarbon receptor-dependent regulation of miR-196a expression controls lung fibroblast apoptosis but not proliferation

    SciTech Connect

    Hecht, Emelia; Zago, Michela; Sarill, Miles

    2014-11-01

    The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor implicated in the regulation of apoptosis and proliferation. Although activation of the AhR by xenobiotics such as dioxin inhibits the cell cycle and control apoptosis, paradoxically, AhR expression also promotes cell proliferation and survival independent of exogenous ligands. The microRNA (miRNA) miR-196a has also emerged as a regulator of proliferation and apoptosis but a relationship between the AhR and miR-196a is not known. Therefore, we hypothesized that AhR-dependent regulation of endogenous miR-196a expression would promote cell survival and proliferation. Utilizing lung fibroblasts from AhR deficient (AhR{sup −/−}) and wild-type (AhR{supmore » +/+}) mice, we show that there is ligand-independent regulation of miRNA, including low miR-196a in AhR{sup −/−} cells. Validation by qRT-PCR revealed a significant decrease in basal expression of miR-196a in AhR{sup −/−} compared to AhR{sup +/+} cells. Exposure to AhR agonists benzo[a]pyrene (B[a]P) and FICZ as well as AhR antagonist CH-223191 decreased miR-196a expression in AhR{sup +/+} fibroblasts concomitant with decreased AhR protein levels. There was increased proliferation only in AhR{sup +/+} lung fibroblasts in response to serum, corresponding to a decrease in p27{sup KIP1} protein, a cyclin-dependent kinase inhibitor. Increasing the cellular levels of miR-196a had no effect on proliferation or expression of p27{sup KIP1} in AhR{sup −/−} fibroblasts but attenuated cigarette smoke-induced apoptosis. This study provides the first evidence that AhR expression is essential for the physiological regulation of cellular miRNA levels- including miR-196a. Future experiments designed to elucidate the functional relationship between the AhR and miR-196a may delineate additional novel ligand-independent roles for the AhR. - Highlights: • The AhR controls proliferation and apoptosis in lung cells. • The AhR regulates

  2. The regulation mechanisms of AhR by molecular chaperone complex.

    PubMed

    Kudo, Ikuru; Hosaka, Miki; Haga, Asami; Tsuji, Noriko; Nagata, Yuhtaroh; Okada, Hirotaka; Fukuda, Kana; Kakizaki, Yuka; Okamoto, Tomoya; Grave, Ewa; Itoh, Hideaki

    2018-03-01

    The AhR, so called the dioxin receptor, is a member of the nuclear receptor superfamily. The ligand-free AhR forms a cytosolic protein complex with the molecular chaperone HSP90, co-chaperone p23, and XAP2 in the cytoplasm. Following ligand binding like 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), the AhR translocates into the nucleus. Although it has been reported that HSP90 regulates the translocation of the AhR to the nucleus, the precise activation mechanisms of the AhR have not yet been fully understood. AhR consists of the N-terminal bHLH domain containing NLS and NES, the middle PAS domain and the C-terminal transactivation domain. The PAS domain is familiar as a ligand and HSP90 binding domain. In this study, we focused on the bHLH domain that was thought to be a HSP90 binding domain. We investigated the binding properties of bHLH to HSP90. We analyzed the direct interaction of bHLH with HSP90, p23 and XAP2 using purified proteins. We found that not only the PAS domain but also the bHLH domain bound to HSP90. The bHLH domain forms complex with HSP90, p23 and XAP2. We also determined the bHLH binding domain was HSP90 N-domain. The bHLH domain makes a complex with HSP90, p23 and XAP2 via the HSP90 N-domain. Although the NLS is closed in the absence of a ligand, the structure of AhR will be changed in the presence of a ligand, which leads to NLS open, result in the nuclear translocation of AhR.

  3. Aryl hydrocarbon receptor (AhR) a possible target for the treatment of skin disease.

    PubMed

    Napolitano, Maddalena; Patruno, Cataldo

    2018-07-01

    Aryl hydrocarbon receptor (AhR) is a transcription factor expressed in all skin cells type. It responds to exogenous and endogenous chemicals by inducing/repressing the expression of several genes with toxic or protective effects in a wide range of species and tissues. In healthy skin, AhR signalling contributes to keratinocytes differentiation, skin barrier function, skin pigmentation, and mediates oxidative stress. In the last years, some studies have shown that AhR seems to be involved in the pathogenesis of some skin diseases, even if the currently available data are contradictory. Indeed, while the blocking the AhR signalling activity could prevent or treat skin cancer, the AhR activation seems to be advantageous for the treatment of inflammatory skin diseases. Therefore, for its multifaceted role in skin diseases, AhR seems to be an attractive therapeutic target. Indeed, recently some molecules have been identified for the prevention of skin cancer and the treatment of inflammatory skin diseases. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Pityriazepin and other potent AhR ligands isolated from Malassezia furfur yeast

    PubMed Central

    Mexia, Nikitia; Gaitanis, George; Velegraki, Aristea; Soshilov, Anatoly; Denison, Michael S.; Magiatis, Prokopios

    2015-01-01

    Malassezia furfur yeast strains isolated from diseased human skin preferentially biosynthesize indole alkaloids which can be detected in human skin and are highly potent activators of the aryl hydrocarbon receptor (AhR) and AhR-dependent gene expression. Chemical analysis of an EtOAc extract of a M. furfur strain obtained from diseased human skin and grown on L-tryptophan agar revealed several known AhR active tryptophan metabolites along with a previously unidentified compound, pityriazepin. While its structure resembled that of the known alkaloid pityriacitrin, the comprised pyridine ring had been transformed into an azepinone. The indoloazepinone scaffold of pityriazepin is extremely rare in nature and has only been reported once previously. Pityriazepin, like the other isolated compounds, was found to be a potent activator of the AhR-dependent reporter gene assays in recombinant cell lines derived from four different species, although significant species differences in relative potency was observed. The ability of pityriazepin to competitively bind to the AhR and directly stimulate AhR DNA binding classified it as a new naturally-occurring potent AhR agonist. Malassezia furfur produces an expanded collection of extremely potent naturally occurring AhR agonists, which produce their biological effects in a species-specific manner.1 PMID:25721496

  5. Characterization testing of a 40 Ahr bipolar nickel hydrogen battery

    NASA Astrophysics Data System (ADS)

    Brewer, Jeffrey C.; Manzo, Michelle A.; Gahn, Randall F.

    1989-12-01

    In a continuing effort to develop NiH2 bipolar technology to a point where it can be used efficiently in space flight, testing of a second 40 Ahr, 10-cell bipolar battery has begun. This battery has undergone extensive characterization testing to determine the effects of such operating parameters as charge and discharge rates, temperature, and pressure. The fundamental design of this actively cooled bipolar battery is the same as the first battery. Most of the individual components, however, are from different manufacturers. Different testing procedures as well as certain unique battery characteristics make it difficult to directly compare the two sets of results. In general, the performance of this battery throughout characterization produced expected results. The main differences seen between the first and second batteries occurred during the high-rate discharge portion of the test matrix. The first battery also had poor high-rate discharge results, although better than those of the second battery. Minor changes were made to the battery frame design used for the first battery in an attempt to allow better gas access to the reaction sites for the second build and hopefully improve performance. The changes, however, did not improve the performance of the second battery and could have possibly contributed to the poorer performance that was observed. There are other component differences that could have contributed to the poorer performance of the second battery. The H2 electrode in the second battery was constructed with a Goretex backing which could have limited the high-rate current flow. The gas screen in the second battery had a larger mesh which again could have limited the high-rate current flow. Small scale 2 x 2 batteries are being tested to evaluate the effects of the component variations.

  6. Characterization testing of a 40 Ahr bipolar nickel hydrogen battery

    NASA Technical Reports Server (NTRS)

    Brewer, Jeffrey C.; Manzo, Michelle A.; Gahn, Randall F.

    1989-01-01

    In a continuing effort to develop NiH2 bipolar technology to a point where it can be used efficiently in space flight, testing of a second 40 Ahr, 10-cell bipolar battery has begun. This battery has undergone extensive characterization testing to determine the effects of such operating parameters as charge and discharge rates, temperature, and pressure. The fundamental design of this actively cooled bipolar battery is the same as the first battery. Most of the individual components, however, are from different manufacturers. Different testing procedures as well as certain unique battery characteristics make it difficult to directly compare the two sets of results. In general, the performance of this battery throughout characterization produced expected results. The main differences seen between the first and second batteries occurred during the high-rate discharge portion of the test matrix. The first battery also had poor high-rate discharge results, although better than those of the second battery. Minor changes were made to the battery frame design used for the first battery in an attempt to allow better gas access to the reaction sites for the second build and hopefully improve performance. The changes, however, did not improve the performance of the second battery and could have possibly contributed to the poorer performance that was observed. There are other component differences that could have contributed to the poorer performance of the second battery. The H2 electrode in the second battery was constructed with a Goretex backing which could have limited the high-rate current flow. The gas screen in the second battery had a larger mesh which again could have limited the high-rate current flow. Small scale 2 x 2 batteries are being tested to evaluate the effects of the component variations.

  7. The AhR agonist VAF347 augments retinoic acid-induced differentiation in leukemia cells.

    PubMed

    Ibabao, Christopher N; Bunaciu, Rodica P; Schaefer, Deanna M W; Yen, Andrew

    2015-01-01

    In binary cell-fate decisions, driving one lineage and suppressing the other are conjoined. We have previously reported that aryl hydrocarbon receptor (AhR) promotes retinoic acid (RA)-induced granulocytic differentiation of lineage bipotent HL-60 myeloblastic leukemia cells. VAF347, an AhR agonist, impairs the development of CD14(+)CD11b(+) monocytes from granulo-monocytic (GM) stage precursors. We thus hypothesized that VAF347 propels RA-induced granulocytic differentiation and impairs D3-induced monocytic differentiation of HL-60 cells. Our results show that VAF347 enhanced RA-induced cell cycle arrest, CD11b integrin expression and neutrophil respiratory burst. Granulocytic differentiation is known to be driven by MAPK signaling events regulated by Fgr and Lyn Src-family kinases, the CD38 cell membrane receptor, the Vav1 GEF, the c-Cbl adaptor, as well as AhR, all of which are embodied in a putative signalsome. We found that the VAF347 AhR ligand regulates the signalsome. VAF347 augments RA-induced expression of AhR, Lyn, Vav1, and c-Cbl as well as p47(phox). Several interactions of partners in the signalsome appear to be enhanced: Fgr interaction with c-Cbl, CD38, and with pS259c-Raf and AhR interaction with c-Cbl and Lyn. Thus, we report that, while VAF347 impedes monocytic differentiation induced by 1,25-dihydroxyvitamin D3, VAF347 promotes RA-induced differentiation. This effect seems to involve but not to be limited to Lyn, Vav1, c-Cbl, AhR, and Fgr.

  8. The AhR agonist VAF347 augments retinoic acid-induced differentiation in leukemia cells

    PubMed Central

    Ibabao, Christopher N.; Bunaciu, Rodica P.; Schaefer, Deanna M.W.; Yen, Andrew

    2015-01-01

    In binary cell-fate decisions, driving one lineage and suppressing the other are conjoined. We have previously reported that aryl hydrocarbon receptor (AhR) promotes retinoic acid (RA)-induced granulocytic differentiation of lineage bipotent HL-60 myeloblastic leukemia cells. VAF347, an AhR agonist, impairs the development of CD14+CD11b+ monocytes from granulo-monocytic (GM) stage precursors. We thus hypothesized that VAF347 propels RA-induced granulocytic differentiation and impairs D3-induced monocytic differentiation of HL-60 cells. Our results show that VAF347 enhanced RA-induced cell cycle arrest, CD11b integrin expression and neutrophil respiratory burst. Granulocytic differentiation is known to be driven by MAPK signaling events regulated by Fgr and Lyn Src-family kinases, the CD38 cell membrane receptor, the Vav1 GEF, the c-Cbl adaptor, as well as AhR, all of which are embodied in a putative signalsome. We found that the VAF347 AhR ligand regulates the signalsome. VAF347 augments RA-induced expression of AhR, Lyn, Vav1, and c-Cbl as well as p47phox. Several interactions of partners in the signalsome appear to be enhanced: Fgr interaction with c-Cbl, CD38, and with pS259c-Raf and AhR interaction with c-Cbl and Lyn. Thus, we report that, while VAF347 impedes monocytic differentiation induced by 1,25-dihydroxyvitamin D3, VAF347 promotes RA-induced differentiation. This effect seems to involve but not to be limited to Lyn, Vav1, c-Cbl, AhR, and Fgr. PMID:25941627

  9. The role of aryl hydrocarbon receptor (AhR) in the pathology of pleomorphic adenoma in parotid gland.

    PubMed

    Drozdzik, Agnieszka; Kowalczyk, Robert; Lipski, Mariusz; Łapczuk, Joanna; Urasinska, Elzbieta; Kurzawski, Mateusz

    2016-01-01

    Pleomorphic adenoma (benign mixed tumor) is one of the most common salivary gland tumors. However, molecular mechanisms implicated in its development are not entirely defined. Therefore, the study aimed at definition of aryl hydrocarbon receptor (AhR) involvement in pleomorphic adenoma pathology, as the AhR controlled gene system was documented to play a role in development of various human tumors. The study was carried out in pleomorphic adenoma and control parotid gland tissues where gene expression of AHR, AhR nuclear translocator (ARNT), AhR repressor (AHRR), as well as AhR controlled genes: CYP1A1 and CYP1B1, at mRNA and protein (immunohistochemistry) levels were studied. Functional evaluation of AhR system was evaluated in HSY cells (human parotid gland adenocarcinoma cells) using 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as AhR specific inducer. Pleomorphic adenoma specimens showed cytoplasmic and nuclear AhR expression in epithelial cells as well as in mesenchymal cells. In parotid gland AhR was expressed in cytoplasm of duct cells. Quantitative expression at mRNA level showed significantly higher expression of AHR, ARNT and CYP1B1, and comparable levels of CYP1A1 in pleomorphic adenoma tissue in comparison to healthy parotid gland. The HSY cell study revealed significantly higher expression level of AHRR in HSY as compared with MCF-7 cells (human breast adenocarcinoma cell line used as reference). Upon TCDD stimulation a drop in AHRR level in HSY cells and an increase in MCF-7 cells were observed. The HSY and MCF-7 cell proliferation rate (measured by WST-1 test) was not affected by TCDD. Summarizing both in vitro and in vivo observations it can be stated that AhR system may play a role in the pathology of pleomorphic adenoma. Copyright © 2015. Published by Elsevier Ltd.

  10. Regulation of zebrafish CYP3A65 transcription by AHR2

    SciTech Connect

    Chang, Chin-Teng; Chung, Hsin-Yu; Su, Hsiao-Ting

    2013-07-15

    CYP3A proteins are the most abundant CYPs in the liver and intestines, and they play a pivotal role in drug metabolism. In mammals, CYP3A genes are induced by various xenobiotics through processes mediated by PXR. We previously identified zebrafish CYP3A65 as a CYP3A ortholog that is constitutively expressed in gastrointestinal tissues, and is upregulated by treatment with dexamethasone, rifampicin or tetrachlorodibenzo-p-dioxin (TCDD). However, the underlying mechanism of TCDD-mediated CYP3A65 transcription is unclear. Here we generated two transgenic zebrafish, Tg(CYP3A65S:EGFP) and Tg(CYP3A65L:EGFP), which contain 2.1 and 5.4 kb 5′ flanking sequences, respectively, of the CYP3A65 gene upstream of EGFP. Both transgenicmore » lines express EGFP in larval gastrointestinal tissues in a pattern similar to that of the endogenous CYP3A65 gene. Moreover, EGFP expression can be significantly induced by TCDD exposure during the larval stage. In addition, EGFP expression can be stimulated by kynurenine, a putative AHR ligand produced during tryptophan metabolism. AHRE elements in the upstream regulatory region of the CYP3A65 gene are indispensible for basal and TCDD-induced transcription. Furthermore, the AHR2 DNA and ligand-binding domains are required to mediate effective CYP3A65 transcription. AHRE sequences are present in the promoters of many teleost CYP3 genes, but not of mammalian CYP3 genes, suggesting that AHR/AHR2-mediated transcription is likely a common regulatory mechanism for teleost CYP3 genes. It may also reflect the different environments that terrestrial and aquatic organisms encounter. - Highlights: • Tg(CYP3A65:EGFP) and CYP3A65 exhibits identical expression pattern. • CYP3A65 can be significantly induced by TCDD or kynurenine. • The AHRE elements are required to mediate CYP3A65 transcription. • The AHR2 DNA and ligand-binding domains are required for CYP3A65 transcription. • AHRE elements are present in many teleost CYP3 genes, but not in

  11. AhR transcriptional activity in serum of Inuits across Greenlandic districts

    PubMed Central

    Long, Manhai; Deutch, Bente; Bonefeld-Jorgensen, Eva C

    2007-01-01

    Background Human exposure to lipophilic persistent organic pollutants (POPs) including polychlorinated dibenzo-p-dioxins/furans (PCDDs/PCDFs), polychlorinated biphenyls (PCBs) and organochlorine pesticide is ubiquitous. The individual is exposed to a complex mixture of POPs being life-long beginning during critical developmental windows. Exposure to POPs elicits a number of species- and tissue-specific toxic responses, many of which involve the aryl hydrocarbon receptor (AhR). The aim of this study was to compare the actual level of integrated AhR transcriptional activity in the lipophilic serum fraction containing the actual POP mixture among Inuits from different districts in Greenland, and to evaluate whether the AhR transactivity is correlated to the bio-accumulated POPs and/or lifestyle factors. Methods The study included 357 serum samples from the Greenlandic districts: Nuuk and Sisimiut (South West Coast), Qaanaaq (North Coast) and Tasiilaq (East Coast). The bio-accumulated serum POPs were extracted by ethanol: hexane and clean-up on Florisil columns. Effects of the serum extract on the AhR transactivity was determined using the Hepa 1.12cR mouse hepatoma cell line carrying an AhR-luciferase reporter gene, and the data was evaluated for possible association to the serum levels of 14 PCB congeners, 10 organochlorine pesticide residues and/or lifestyle factors. Results In total 85% of the Inuit samples elicited agonistic AhR transactivity in a district dependent pattern. The median level of the AhR-TCDD equivalent (AhR-TEQ) of the separate genders was similar in the different districts. For the combined data the order of the median AhR-TEQ was Tasiilaq > Nuuk ≥ Sisimiut > Qaanaaq possibly being related to the different composition of POPs. In overall, the AhR transactivity was inversely correlated to the levels of sum POPs, age and/or intake of marine food. Conclusion i) We observed that the proportion of dioxin like (DL) compounds in the POP mixture was the

  12. Trace derivatives of kynurenine potently activate the aryl hydrocarbon receptor (AHR).

    PubMed

    Seok, Seung-Hyeon; Ma, Zhi-Xiong; Feltenberger, John B; Chen, Hongbo; Chen, Hui; Scarlett, Cameron; Lin, Ziqing; Satyshur, Kenneth A; Cortopassi, Marissa; Jefcoate, Colin R; Ge, Ying; Tang, Weiping; Bradfield, Christopher A; Xing, Yongna

    2018-02-09

    Cellular metabolites act as important signaling cues, but are subject to complex unknown chemistry. Kynurenine is a tryptophan metabolite that plays a crucial role in cancer and the immune system. Despite its atypical, non-ligand-like, highly polar structure, kynurenine activates the aryl hydrocarbon receptor (AHR), a PER, ARNT, SIM (PAS) family transcription factor that responds to diverse environmental and cellular ligands. The activity of kynurenine is increased 100-1000-fold by incubation or long-term storage and relies on the hydrophobic ligand-binding pocket of AHR, with identical structural signatures for AHR induction before and after activation. We purified trace-active derivatives of kynurenine and identified two novel, closely related condensation products, named trace-extended aromatic condensation products (TEACOPs), which are active at low picomolar levels. The synthesized compound for one of the predicted structures matched the purified compound in both chemical structure and AHR pharmacology. Our study provides evidence that kynurenine acts as an AHR pro-ligand, which requires novel chemical conversions to act as a receptor agonist. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. From the Cover: Development and Application of a Dual Rat and Human AHR Activation Assay.

    PubMed

    Brown, Martin R; Garside, Helen; Thompson, Emma; Atwal, Saseela; Bean, Chloe; Goodall, Tony; Sullivan, Michael; Graham, Mark J

    2017-12-01

    Significant prolonged aryl hydrocarbon receptor (AHR) activation, classically exhibited following exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin, can cause a variety of undesirable toxicological effects. Novel pharmaceutical chemistries also have the potential to cause activation of AHR and consequent toxicities in pre-clinical species and man. Previous methods either employed relatively expensive and low-throughput primary hepatocyte dosing with PCR endpoint, or low resolution overexpressing reporter gene assays. We have developed, validated and applied an in vitro microtitre plate imaging-based medium throughput screening assay for the assessment of endogenous species-specific AHR activation potential via detection of induction of the surrogate transcriptional target Cytochrome P450 CYP1A1. Routine testing of pharmaceutical drug development candidate chemistries using this assay can influence the chemical design process and highlight AHR liabilities. This assay should be introduced such that human AHR activation liability is flagged early for confirmatory testing. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  14. Coal tar induces AHR-dependent skin barrier repair in atopic dermatitis

    PubMed Central

    van den Bogaard, Ellen H.; Bergboer, Judith G.M.; Vonk-Bergers, Mieke; van Vlijmen-Willems, Ivonne M.J.J.; Hato, Stanleyson V.; van der Valk, Pieter G.M.; Schröder, Jens Michael; Joosten, Irma; Zeeuwen, Patrick L.J.M.; Schalkwijk, Joost

    2013-01-01

    Topical application of coal tar is one of the oldest therapies for atopic dermatitis (AD), a T helper 2 (Th2) lymphocyte–mediated skin disease associated with loss-of-function mutations in the skin barrier gene, filaggrin (FLG). Despite its longstanding clinical use and efficacy, the molecular mechanism of coal tar therapy is unknown. Using organotypic skin models with primary keratinocytes from AD patients and controls, we found that coal tar activated the aryl hydrocarbon receptor (AHR), resulting in induction of epidermal differentiation. AHR knockdown by siRNA completely abrogated this effect. Coal tar restored filaggrin expression in FLG-haploinsufficient keratinocytes to wild-type levels, and counteracted Th2 cytokine–mediated downregulation of skin barrier proteins. In AD patients, coal tar completely restored expression of major skin barrier proteins, including filaggrin. Using organotypic skin models stimulated with Th2 cytokines IL-4 and IL-13, we found coal tar to diminish spongiosis, apoptosis, and CCL26 expression, all AD hallmarks. Coal tar interfered with Th2 cytokine signaling via dephosphorylation of STAT6, most likely due to AHR-regulated activation of the NRF2 antioxidative stress pathway. The therapeutic effect of AHR activation herein described opens a new avenue to reconsider AHR as a pharmacological target and could lead to the development of mechanism-based drugs for AD. PMID:23348739

  15. Coal tar induces AHR-dependent skin barrier repair in atopic dermatitis.

    PubMed

    van den Bogaard, Ellen H; Bergboer, Judith G M; Vonk-Bergers, Mieke; van Vlijmen-Willems, Ivonne M J J; Hato, Stanleyson V; van der Valk, Pieter G M; Schröder, Jens Michael; Joosten, Irma; Zeeuwen, Patrick L J M; Schalkwijk, Joost

    2013-02-01

    Topical application of coal tar is one of the oldest therapies for atopic dermatitis (AD), a T helper 2 (Th2) lymphocyte-mediated skin disease associated with loss-of-function mutations in the skin barrier gene, filaggrin (FLG). Despite its longstanding clinical use and efficacy, the molecular mechanism of coal tar therapy is unknown. Using organotypic skin models with primary keratinocytes from AD patients and controls, we found that coal tar activated the aryl hydrocarbon receptor (AHR), resulting in induction of epidermal differentiation. AHR knockdown by siRNA completely abrogated this effect. Coal tar restored filaggrin expression in FLG-haploinsufficient keratinocytes to wild-type levels, and counteracted Th2 cytokine-mediated downregulation of skin barrier proteins. In AD patients, coal tar completely restored expression of major skin barrier proteins, including filaggrin. Using organotypic skin models stimulated with Th2 cytokines IL-4 and IL-13, we found coal tar to diminish spongiosis, apoptosis, and CCL26 expression, all AD hallmarks. Coal tar interfered with Th2 cytokine signaling via dephosphorylation of STAT6, most likely due to AHR-regulated activation of the NRF2 antioxidative stress pathway. The therapeutic effect of AHR activation herein described opens a new avenue to reconsider AHR as a pharmacological target and could lead to the development of mechanism-based drugs for AD.

  16. Loss of NR2E3 represses AHR by LSD1 reprogramming, is associated with poor prognosis in liver cancer.

    PubMed

    Khanal, Tilak; Choi, Kwangmin; Leung, Yuet-Kin; Wang, Jiang; Kim, Dasom; Janakiram, Vinothini; Cho, Sung-Gook; Puga, Alvaro; Ho, Shuk-Mei; Kim, Kyounghyun

    2017-09-06

    The aryl hydrocarbon receptor (AHR) plays crucial roles in inflammation, metabolic disorder, and cancer. However, the molecular mechanisms regulating AHR expression remain unknown. Here, we found that an orphan nuclear NR2E3 maintains AHR expression, and forms an active transcriptional complex with transcription factor Sp1 and coactivator GRIP1 in MCF-7 human breast and HepG2 liver cancer cell lines. NR2E3 loss promotes the recruitment of LSD1, a histone demethylase of histone 3 lysine 4 di-methylation (H3K4me2), to the AHR gene promoter region, resulting in repression of AHR expression. AHR expression and responsiveness along with H3K4me2 were significantly reduced in the livers of Nr2e3 rd7 (Rd7) mice that express low NR2E3 relative to the livers of wild-type mice. SP2509, an LSD1 inhibitor, fully restored AHR expression and H3K4me2 levels in Rd7 mice. Lastly, we demonstrated that both AHR and NR2E3 are significantly associated with good clinical outcomes in liver cancer. Together, our results reveal a novel link between NR2E3, AHR, and liver cancer via LSD1-mediated H3K4me2 histone modification in liver cancer development.

  17. Estrogenic and AhR activities in dissolved phase and suspended solids from wastewater treatment plants.

    PubMed

    Dagnino, Sonia; Gomez, Elena; Picot, Bernadette; Cavaillès, Vincent; Casellas, Claude; Balaguer, Patrick; Fenet, Hélène

    2010-05-15

    The distribution of estrogen receptor (ERalpha) and Aryl Hydrocarbon Receptor (AhR) activities between the dissolved phase and suspended solids were investigated during wastewater treatment. Three wastewater treatment plants with different treatment technologies (waste stabilization ponds (WSPs), trickling filters (TFs) and activated sludge supplemented with a biofilter system (ASB)) were sampled. Estrogenic and AhR activities were detected in both phases in influents and effluents. Estrogenic and AhR activities in wastewater influents ranged from 41.8 to 79 ng/L E(2) Eq. and from 37.9 to 115.5 ng/L TCDD Eq. in the dissolved phase and from 5.5 to 88.6 ng/g E(2) Eq. and from 15 to 700 ng/g TCDD Eq. in the suspended solids. For both activities, WSP showed greater or similar removal efficiency than ASB and both were much more efficient than TF which had the lowest removal efficiency. Moreover, our data indicate that the efficiency of removal of ER and AhR activities from the suspended solid phase was mainly due to removal of suspended solids. Indeed, ER and AhR activities were detected in the effluent suspended solid phase indicating that suspended solids, which are usually not considered in these types of studies, contribute to environmental contamination by endocrine disrupting compounds and should therefore be routinely assessed for a better estimation of the ER and AhR activities released in the environment. Copyright 2010 Elsevier B.V. All rights reserved.

  18. Dibutyl Phthalate (DBP)-Induced Apoptosis and Neurotoxicity are Mediated via the Aryl Hydrocarbon Receptor (AhR) but not by Estrogen Receptor Alpha (ERα), Estrogen Receptor Beta (ERβ), or Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) in Mouse Cortical Neurons.

    PubMed

    Wójtowicz, Anna K; Szychowski, Konrad A; Wnuk, Agnieszka; Kajta, Małgorzata

    2017-01-01

    Dibutyl phthalate (di-n-butyl phthalate, DBP) is one of the most commonly used phthalate esters. DBP is widely used as a plasticizer in a variety of household industries and consumer products. Because phthalates are not chemically bound to products, they can easily leak out to enter the environment. DBP can pass through the placental and blood-brain barriers due to its chemical structure, but little is known about its mechanism of action in neuronal cells. This study demonstrated the toxic and apoptotic effects of DBP in mouse neocortical neurons in primary cultures. DBP stimulated caspase-3 and LDH activities as well as ROS formation in a concentration (10 nM-100 µM) and time-dependent (3-48 h) manner. DBP induced ROS formation at nanomolar concentrations, while it activated caspase-3 and LDH activities at micromolar concentrations. The biochemical effects of DBP were accompanied by decreased cell viability and induction of apoptotic bodies. Exposure to DBP reduced Erα and Pparγ mRNA expression levels, which were inversely correlated with protein expression of the receptors. Treatment with DBP enhanced Ahr mRNA expression, which was reflected by the increased AhR protein level observed at 3 h after exposure. ERα, ERβ, and PPARγ antagonists stimulated DBP-induced caspase-3 and LDH activities. AhR silencing demonstrated that DBP-induced apoptosis and neurotoxicity are mediated by AhR, which is consistent with the results from DBP-induced enhancement of AhR mRNA and protein expression. Our study showed that AhR is involved in DBP-induced apoptosis and neurotoxicity, while the ERs and PPARγ signaling pathways are impaired by the phthalate.

  19. Red Clover Aryl Hydrocarbon Receptor (AhR) and Estrogen Receptor (ER) Agonists Enhance Genotoxic Estrogen Metabolism

    PubMed Central

    2017-01-01

    Many women consider botanical dietary supplements (BDSs) as safe alternatives to hormone therapy for menopausal symptoms. However, the effect of BDSs on breast cancer risk is largely unknown. In the estrogen chemical carcinogenesis pathway, P450 1B1 metabolizes estrogens to 4-hydroxylated catechols, which are oxidized to genotoxic quinones that initiate and promote breast cancer. In contrast, P450 1A1 catalyzed 2-hydroxylation represents a detoxification pathway. The current study evaluated the effects of red clover, a popular BDS used for women’s health, and its isoflavones, biochanin A (BA), formononetin (FN), genistein (GN), and daidzein (DZ), on estrogen metabolism. The methoxy estrogen metabolites (2-MeOE1, 4-MeOE1) were measured by LC-MS/MS, and CYP1A1 and CYP1B1 gene expression was analyzed by qPCR. Nonmalignant ER-negative breast epithelial cells (MCF-10A) and ER-positive breast cancer cells (MCF-7) were derived from normal breast epithelial tissue and ER+ breast cancer tissue. Red clover extract (RCE, 10 μg/mL) and isoflavones had no effect on estrogen metabolism in MCF-10A cells. However, in MCF-7 cells, RCE treatments downregulated CYP1A1 expression and enhanced genotoxic metabolism (4-MeOE1/CYP1B1 > 2-MeOE1/CYP1A1). Experiments with the isoflavones showed that the AhR agonists (BA, FN) preferentially induced CYP1B1 expression as well as 4-MeOE1. In contrast, the ER agonists (GN, DZ) downregulated CYP1A1 expression likely through an epigenetic mechanism. Finally, the ER antagonist ICI 182,780 potentiated isoflavone-induced XRE-luciferase reporter activity and reversed GN and DZ induced downregulation of CYP1A1 expression. Overall, these studies show that red clover and its isoflavones have differential effects on estrogen metabolism in “normal” vs breast cancer cells. In breast cancer cells, the AhR agonists stimulate genotoxic metabolism, and the ER agonists downregulate the detoxification pathway. These data may suggest that especially breast

  20. Apoptotic cell-induced AhR activity is required for immunological tolerance and suppression of systemic lupus erythematosus in mice and humans.

    PubMed

    Shinde, Rahul; Hezaveh, Kebria; Halaby, Marie Jo; Kloetgen, Andreas; Chakravarthy, Ankur; da Silva Medina, Tiago; Deol, Reema; Manion, Kieran P; Baglaenko, Yuriy; Eldh, Maria; Lamorte, Sara; Wallace, Drew; Chodisetti, Sathi Babu; Ravishankar, Buvana; Liu, Haiyun; Chaudhary, Kapil; Munn, David H; Tsirigos, Aristotelis; Madaio, Michael; Gabrielsson, Susanne; Touma, Zahi; Wither, Joan; De Carvalho, Daniel D; McGaha, Tracy L

    2018-06-01

    The transcription factor AhR modulates immunity at multiple levels. Here we report that phagocytes exposed to apoptotic cells exhibited rapid activation of AhR, which drove production of the cytokine IL-10. Activation of AhR was dependent on interactions between apoptotic-cell DNA and the pattern-recognition receptor TLR9 that was required for the prevention of immune responses to DNA and histones in vivo. Moreover, disease progression in mouse systemic lupus erythematosus (SLE) correlated with strength of the AhR signal, and the disease course could be altered by modulation of AhR activity. Deletion of AhR in the myeloid lineage caused systemic autoimmunity in mice, and an enhanced AhR transcriptional signature correlated with disease in patients with SLE. Thus, AhR activity induced by apoptotic cell phagocytes maintains peripheral tolerance.

  1. In Vivo Characterization of an AHR-Dependent Long Noncoding RNA Required for Proper Sox9b Expression.

    PubMed

    Garcia, Gloria R; Goodale, Britton C; Wiley, Michelle W; La Du, Jane K; Hendrix, David A; Tanguay, Robert L

    2017-06-01

    Xenobiotic activation of the aryl hydrocarbon receptor (AHR) by 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) prevents the proper formation of craniofacial cartilage and the heart in developing zebrafish. Downstream molecular targets responsible for AHR-dependent adverse effects remain largely unknown; however, in zebrafish sox9b has been identified as one of the most-reduced transcripts in several target organs and is hypothesized to have a causal role in TCDD-induced toxicity. The reduction of sox9b expression in TCDD-exposed zebrafish embryos has been shown to contribute to heart and jaw malformation phenotypes. The mechanisms by which AHR2 (functional ortholog of mammalian AHR) activation leads to reduced sox9b expression levels and subsequent target organ toxicity are unknown. We have identified a novel long noncoding RNA ( slincR ) that is upregulated by strong AHR ligands and is located adjacent to the sox9b gene. We hypothesize that slincR is regulated by AHR2 and transcriptionally represses sox9b. The slincR transcript functions as an RNA macromolecule, and slincR expression is AHR2 dependent. Antisense knockdown of slincR results in an increase in sox9b expression during both normal development and AHR2 activation, which suggests relief in repression. During development, slincR was expressed in tissues with sox9 essential functions, including the jaw/snout region, otic vesicle, eye, and brain. Reducing the levels of slincR resulted in altered neurologic and/or locomotor behavioral responses. Our results place slincR as an intermediate between AHR2 activation and the reduction of sox9b mRNA in the AHR2 signaling pathway. Copyright © 2017 by The Author(s).

  2. In Vivo Characterization of an AHR-Dependent Long Noncoding RNA Required for Proper Sox9b Expression

    PubMed Central

    Garcia, Gloria R.; Goodale, Britton C.; Wiley, Michelle W.; La Du, Jane K.; Hendrix, David A.

    2017-01-01

    Xenobiotic activation of the aryl hydrocarbon receptor (AHR) by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) prevents the proper formation of craniofacial cartilage and the heart in developing zebrafish. Downstream molecular targets responsible for AHR-dependent adverse effects remain largely unknown; however, in zebrafish sox9b has been identified as one of the most-reduced transcripts in several target organs and is hypothesized to have a causal role in TCDD-induced toxicity. The reduction of sox9b expression in TCDD-exposed zebrafish embryos has been shown to contribute to heart and jaw malformation phenotypes. The mechanisms by which AHR2 (functional ortholog of mammalian AHR) activation leads to reduced sox9b expression levels and subsequent target organ toxicity are unknown. We have identified a novel long noncoding RNA (slincR) that is upregulated by strong AHR ligands and is located adjacent to the sox9b gene. We hypothesize that slincR is regulated by AHR2 and transcriptionally represses sox9b. The slincR transcript functions as an RNA macromolecule, and slincR expression is AHR2 dependent. Antisense knockdown of slincR results in an increase in sox9b expression during both normal development and AHR2 activation, which suggests relief in repression. During development, slincR was expressed in tissues with sox9 essential functions, including the jaw/snout region, otic vesicle, eye, and brain. Reducing the levels of slincR resulted in altered neurologic and/or locomotor behavioral responses. Our results place slincR as an intermediate between AHR2 activation and the reduction of sox9b mRNA in the AHR2 signaling pathway. PMID:28385905

  3. RELATIONSHIPS BETWEEN RESIDUES OF AHR AGONISTS IN FISH AND CONCENTRATIONS IN WATER AND SEDIMENTS

    EPA Science Inventory

    Relationships between Residues of AhR Agonists in Fish and Concentrations in Water and Sediment. Cook, PM*, Burkhard, LP, Mount, DR, US-EPA, NHEERL, MED, Duluth, MN. The bioaccumulation visualization approach of Burkhard et al. (2002) can be effectively used to describe the bioa...

  4. Intersection of AHR and Wnt Signaling in Development, Health, and Disease

    PubMed Central

    Schneider, Andrew J.; Branam, Amanda M.; Peterson, Richard E.

    2014-01-01

    The AHR (aryl hydrocarbon receptor) and Wnt (wingless-related MMTV integration site) signaling pathways have been conserved throughout evolution. Appropriately regulated signaling through each pathway is necessary for normal development and health, while dysregulation can lead to developmental defects and disease. Though both pathways have been vigorously studied, there is relatively little research exploring the possibility of crosstalk between these pathways. In this review, we provide a brief background on (1) the roles of both AHR and Wnt signaling in development and disease, and (2) the molecular mechanisms that characterize activation of each pathway. We also discuss the need for careful and complete experimental evaluation of each pathway and describe existing research that explores the intersection of AHR and Wnt signaling. Lastly, to illustrate in detail the intersection of AHR and Wnt signaling, we summarize our recent findings which show that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced disruption of Wnt signaling impairs fetal prostate development. PMID:25286307

  5. EXPRESSION OF AHR AND ARNT MRNA IN CULTURED HUMAN ENDOMETRIAL EXPLANTS EXPOSED TO TCDD

    EPA Science Inventory

    Expression of AhR and ARNT mRNA in cultured human endometrial explants exposed to TCDD.

    Pitt JA, Feng L, Abbott BD, Schmid J, Batt RE, Costich TG, Koury ST, Bofinger DP.

    Curriculum in Toxicology, University of North Carolina, Chapel Hill, NC 27599, USA.

    Endom...

  6. Hop (Humulus lupulus L.) Extract and 6-Prenylnaringenin Induce P450 1A1 Catalyzed Estrogen 2-Hydroxylation

    PubMed Central

    2016-01-01

    Humulus lupulus L. (hops) is a popular botanical dietary supplement used by women as a sleep aid and for postmenopausal symptom relief. In addition to its efficacy for menopausal symptoms, hops can also modulate the chemical estrogen carcinogenesis pathway and potentially protect women from breast cancer. In the present study, an enriched hop extract and the key bioactive compounds [6-prenylnarigenin (6-PN), 8-prenylnarigenin (8-PN), isoxanthohumol (IX), and xanthohumol (XH)] were tested for their effects on estrogen metabolism in breast cells (MCF-10A and MCF-7). The methoxyestrones (2-/4-MeOE1) were analyzed as biomarkers for the nontoxic P450 1A1 catalyzed 2-hydroxylation and the genotoxic P450 1B1 catalyzed 4-hydroxylation pathways, respectively. The results indicated that the hop extract and 6-PN preferentially induced the 2-hydroxylation pathway in both cell lines. 8-PN only showed slight up-regulation of metabolism in MCF-7 cells, whereas IX and XH did not have significant effects in either cell line. To further explore the influence of hops and its bioactive marker compounds on P450 1A1/1B1, mRNA expression and ethoxyresorufin O-dealkylase (EROD) activity were measured. The results correlated with the metabolism data and showed that hop extract and 6-PN preferentially enhanced P450 1A1 mRNA expression and increased P450 1A1/1B1 activity. The aryl hydrocarbon receptor (AhR) activation by the isolated compounds was tested using xenobiotic response element (XRE) luciferase construct transfected cells. 6-PN was found to be an AhR agonist that significantly induced XRE activation and inhibited 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced XRE activity. 6-PN mediated induction of EROD activity was also inhibited by the AhR antagonist CH223191. These data show that the hop extract and 6-PN preferentially enhance the nontoxic estrogen 2-hydroxylation pathway through AhR mediated up-regulation of P450 1A1, which further emphasizes the importance of

  7. Functional and phenotypic effects of AhR activation in inflammatory dendritic cells

    SciTech Connect

    Bankoti, Jaishree; Center for Environmental Health Sciences, University of Montana, Missoula, MT; Rase, Ben

    2010-07-15

    Aryl hydrocarbon receptor (AhR) activation by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces immune suppression. Dendritic cells (DCs) are key antigen presenting cells governing T cell activation and differentiation. However, the consequences of AhR activation in DCs are not fully defined. We hypothesized that AhR activation alters DC differentiation and generates dysfunctional DCs. To test this hypothesis, inflammatory bone marrow-derived DCs (BMDCs) from C57Bl/6 mice were generated in the presence of vehicle or TCDD. TCDD decreased CD11c expression but increased MHC class II, CD86 and CD25 expression on the BMDCs. The effects of TCDD were strictly AhR-dependent but not exclusively DRE-mediated. Similar effects weremore » observed with two natural AhR ligands, 6-formylindolo[3,2-b]carbazole (FICZ) and 2-(1H-Indol-3-ylcarbonyl)-4-thiazolecarboxylic acid (ITE). TCDD increased LPS- and CpG-induced IL-6 and TNF-{alpha} production by BMDCs but decreased their NO production. TCDD decreased CpG-induced IL-12p70 production by BMDCs but did not affect their secretion of IL-10. TCDD downregulated LPS- and CpG-induced NF-kB p65 levels and induced a trend towards upregulation of RelB levels in the BMDCs. AhR activation by TCDD modulated BMDC uptake of both soluble and particulate antigens. Induction of indoleamine-2,3-dioxygenase (IDO) and TGF-{beta}3 has been implicated in the generation of regulatory T cells following AhR activation. TCDD increased IDO1, IDO2 and TGF-{beta}3 mRNA levels in BMDCs as compared to vehicle. Despite the induction of regulatory mediators, TCDD-treated BMDCs failed to suppress antigen-specific T cell activation. Thus, AhR activation can directly alter the differentiation and innate functions of inflammatory DCs without affecting their ability to successfully interact with T cells.« less

  8. AHR2 morpholino knockdown reduces the toxicity of total particulate matter to zebrafish embryos

    SciTech Connect

    Massarsky, Andrey, E-mail: andrey.massarsky@duke.e

    The zebrafish embryo has been proposed as a ‘bridge model’ to study the effects of cigarette smoke on early development. Previous studies showed that exposure to total particulate matter (TPM) led to adverse effects in developing zebrafish, and suggested that the antioxidant and aryl hydrocarbon receptor (AHR) pathways play important roles. This study investigated the roles of these two pathways in mediating TPM toxicity. The study consisted of four experiments. In experiment I, zebrafish embryos were exposed from 6 h post fertilization (hpf) until 96 hpf to TPM{sub 0.5} and TPM{sub 1.0} (corresponding to 0.5 and 1.0 μg/mL equi-nicotine units)more » in the presence or absence of an antioxidant (N-acetyl cysteine/NAC) or a pro-oxidant (buthionine sulfoximine/BSO). In experiment II, TPM exposures were performed in embryos that were microinjected with nuclear factor erythroid 2-related factor 2 (Nrf2), AHR2, cytochrome P450 1A (CYP1A), or CYP1B1 morpholinos, and deformities were assessed. In experiment III, embryos were exposed to TPM, and embryos/larvae were collected at 24, 48, 72, and 96 hpf to assess several genes associated with the antioxidant and AHR pathways. Lastly, experiment IV assessed the activity and protein levels of CYP1A and CYP1B1 after exposure to TPM. We demonstrate that the incidence of TPM-induced deformities was generally not affected by NAC/BSO treatments or Nrf2 knockdown. In contrast, AHR2 knockdown reduced, while CYP1A or CYP1B1 knockdowns elevated the incidence of some deformities. Moreover, as shown by gene expression the AHR pathway, but not the antioxidant pathway, was induced in response to TPM exposure, providing further evidence for its importance in mediating TPM toxicity. - Highlights: • Total particulate matter (TPM) is the particulate phase of cigarette smoke. • Zebrafish is proposed as a ‘bridge model’ to study the effects of TPM. • We investigate the roles of antioxidant and aryl hydrocarbon receptor (AHR

  9. Genome-wide mapping and analysis of aryl hydrocarbon receptor (AHR)- and aryl hydrocarbon receptor repressor (AHRR)-binding sites in human breast cancer cells.

    PubMed

    Yang, Sunny Y; Ahmed, Shaimaa; Satheesh, Somisetty V; Matthews, Jason

    2018-01-01

    The aryl hydrocarbon receptor (AHR) mediates the toxic actions of environmental contaminants, such as 2,3,7,8-tetrachlorodibenzo-ρ-dioxin (TCDD), and also plays roles in vascular development, the immune response, and cell cycle regulation. The AHR repressor (AHRR) is an AHR-regulated gene and a negative regulator of AHR; however, the mechanisms of AHRR-dependent repression of AHR are unclear. In this study, we compared the genome-wide binding profiles of AHR and AHRR in MCF-7 human breast cancer cells treated for 24 h with TCDD using chromatin immunoprecipitation followed by next-generation sequencing (ChIP-Seq). We identified 3915 AHR- and 2811 AHRR-bound regions, of which 974 (35%) were common to both datasets. When these 24-h datasets were also compared with AHR-bound regions identified after 45 min of TCDD treatment, 67% (1884) of AHRR-bound regions overlapped with those of AHR. This analysis identified 994 unique AHRR-bound regions. AHRR-bound regions mapped closer to promoter regions when compared with AHR-bound regions. The AHRE was identified and overrepresented in AHR:AHRR-co-bound regions, AHR-only regions, and AHRR-only regions. Candidate unique AHR- and AHRR-bound regions were validated by ChIP-qPCR and their ability to regulate gene expression was confirmed by luciferase reporter gene assays. Overall, this study reveals that AHR and AHRR exhibit similar but also distinct genome-wide binding profiles, supporting the notion that AHRR is a context- and gene-specific repressor of AHR activity.

  10. AhR modulates the IL-22-producing cell proliferation/recruitment in imiquimod-induced psoriasis mouse model.

    PubMed

    Cochez, Perrine M; Michiels, Camille; Hendrickx, Emilie; Van Belle, Astrid B; Lemaire, Muriel M; Dauguet, Nicolas; Warnier, Guy; de Heusch, Magali; Togbe, Dieudonnée; Ryffel, Bernhard; Coulie, Pierre G; Renauld, Jean-Christophe; Dumoutier, Laure

    2016-06-01

    IL-22 has a detrimental role in skin inflammatory processes, for example in psoriasis. As transcription factor, AhR controls the IL-22 production by several cell types (i.e. Th17 cells). Here, we analyzed the role of Ahr in IL-22 production by immune cells in the inflamed skin, using an imiquimod-induced psoriasis mouse model. Our results indicate that IL-22 is expressed in the ear of imiquimod-treated Ahr(-/-) mice but less than in wild-type mice. We then studied the role of AhR on three cell populations known to produce IL-22 in the skin: γδ T cells, Th17 cells, and ILC3, and a novel IL-22-producing cell type identified in this setting: CD4(-) CD8(-) TCRβ(+) T cells. We showed that AhR is required for IL-22 production by Th17, but not by the three other cell types, in the imiquimod-treated ears. Moreover, AhR has a role in the recruitment of γδ T cells, ILC3, and CD4(-) CD8(-) TCRβ(+) T cells into the inflamed skin or in their local proliferation. Taken together, AhR has a direct role in IL-22 production by Th17 cells in the mouse ear skin, but not by γδ T cells, CD4(-) CD8(-) TCRβ(+) T cells and ILCs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Excessive activation of AhR signaling disrupts neuronal migration in the hippocampal CA1 region in the developing mouse.

    PubMed

    Kimura, Eiki; Kubo, Ken-Ichiro; Endo, Toshihiro; Nakajima, Kazunori; Kakeyama, Masaki; Tohyama, Chiharu

    2017-01-01

    The aryl hydrocarbon receptor (AhR) avidly binds dioxin, a ubiquitous environmental contaminant. Disruption of downstream AhR signaling has been reported to alter neuronal development, and rodent offspring exposed to dioxin during gestation and lactation showed abnormalities in learning and memory, emotion, and social behavior. However, the mechanism behind the disrupted AhR signaling and developmental neurotoxicity induced by xenobiotic ligands remains elusive. Therefore, we studied how excessive AhR activation affects neuronal migration in the hippocampal CA1 region of the developing mouse brain. We transfected constitutively active (CA)-AhR, AhR, or control vector plasmids into neurons via in utero electroporation on gestational day 14 and analyzed neuronal positioning in the hippocampal CA1 region of offspring on postnatal day 14. CA-AhR transfection affected neuronal positioning, whereas no change was observed in AhR-transfected or control hippocampus. These results suggest that constitutively activated AhR signaling disrupts neuronal migration during hippocampal development. Further studies are needed to investigate whether such developmental disruption in the hippocampus leads to the abnormal cognition and behavior of rodent offspring upon maternal exposure to AhR xenobiotic ligands.

  12. Cell and region specificity of Aryl hydrocarbon Receptor (AhR) system in the testis and the epididymis.

    PubMed

    Wajda, A; Łapczuk, J; Grabowska, M; Pius-Sadowska, E; Słojewski, M; Laszczynska, M; Urasinska, E; Machalinski, B; Drozdzik, M

    2017-04-01

    Aryl hydrocarbon receptor (AhR) plays multiple important functions in adaptive responses. Exposure to AhR ligands may produce an altered metabolic activity controlled by the AhR pathways, and consequently affect drug/toxin responses, hormonal status and cellular homeostasis. This research revealed species-, cell- and region-specific pattern of the AhR system expression in the rat and human testis and epididymis, complementing the existing knowledge, especially within the epididymal segments. The study showed that AhR level in the rat and human epididymis is higher than in the testis. The downregulation of AhR expression after TCDD treatment was revealed in the spermatogenic cells at different stages and the epididymal epithelial cells, but not in the Sertoli and Leydig cells. Hence, this basic research provides information about the AhR function in the testis and epididymis, which may provide an insight into deleterious effects of drugs, hormones and environmental pollutants on male fertility. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Antioxidant Artemisia princeps Extract Enhances the Expression of Filaggrin and Loricrin via the AHR/OVOL1 Pathway.

    PubMed

    Hirano, Akiko; Goto, Masashi; Mitsui, Tsukasa; Hashimoto-Hachiya, Akiko; Tsuji, Gaku; Furue, Masutaka

    2017-09-11

    The Japanese mugwort, Artemisia princeps ( yomogi in Japanese), has anti-inflammatory and antioxidant effects. Skin care products containing Artemisia princeps extract (APE) are known to improve dry skin symptoms in atopic dermatitis. Atopic dry skin is associated with a marked reduction of skin barrier proteins, such as filaggrin (FLG) and loricrin (LOR). Recently, aryl hydrocarbon receptor (AHR), and its downstream transcription factor OVO-like 1 (OVOL1), have been shown to regulate the gene expression of FLG and LOR. The focus of this paper is to evaluate the effects of APE on the AHR/OVOL1/FLG or LOR pathway since they have remained unknown to this point. We first demonstrated that non-cytotoxic concentrations of APE significantly upregulated antioxidant enzymes, NAD(P)H dehydrogenase quinone 1 and heme oxygenase 1, in human keratinocytes. Even at these low concentrations, APE induced nuclear translocation of AHR and significantly upregulated CYP1A1 (a specific target gene for AHR activation), FLG , and LOR expression. AHR knockdown downregulated OVOL1 expression. The APE-induced upregulation of FLG and LOR was canceled in keratinocytes with AHR or OVOL1 knockdown. In conclusion, antioxidant APE is a potent phytoextract that upregulates FLG and LOR expression in an AHR/OVOL1-dependent manner and this may underpin the barrier-repairing effects of APE in treating atopic dry skin.

  14. Antioxidant Artemisia princeps Extract Enhances the Expression of Filaggrin and Loricrin via the AHR/OVOL1 Pathway

    PubMed Central

    Hirano, Akiko; Goto, Masashi; Mitsui, Tsukasa; Hashimoto-Hachiya, Akiko; Tsuji, Gaku; Furue, Masutaka

    2017-01-01

    The Japanese mugwort, Artemisia princeps (yomogi in Japanese), has anti-inflammatory and antioxidant effects. Skin care products containing Artemisia princeps extract (APE) are known to improve dry skin symptoms in atopic dermatitis. Atopic dry skin is associated with a marked reduction of skin barrier proteins, such as filaggrin (FLG) and loricrin (LOR). Recently, aryl hydrocarbon receptor (AHR), and its downstream transcription factor OVO-like 1 (OVOL1), have been shown to regulate the gene expression of FLG and LOR. The focus of this paper is to evaluate the effects of APE on the AHR/OVOL1/FLG or LOR pathway since they have remained unknown to this point. We first demonstrated that non-cytotoxic concentrations of APE significantly upregulated antioxidant enzymes, NAD(P)H dehydrogenase quinone 1 and heme oxygenase 1, in human keratinocytes. Even at these low concentrations, APE induced nuclear translocation of AHR and significantly upregulated CYP1A1 (a specific target gene for AHR activation), FLG, and LOR expression. AHR knockdown downregulated OVOL1 expression. The APE-induced upregulation of FLG and LOR was canceled in keratinocytes with AHR or OVOL1 knockdown. In conclusion, antioxidant APE is a potent phytoextract that upregulates FLG and LOR expression in an AHR/OVOL1-dependent manner and this may underpin the barrier-repairing effects of APE in treating atopic dry skin. PMID:28892018

  15. AIP mutations impair AhR signaling in pituitary adenoma patients fibroblasts and in GH3 cells.

    PubMed

    Lecoq, Anne-Lise; Viengchareun, Say; Hage, Mirella; Bouligand, Jérôme; Young, Jacques; Boutron, Audrey; Zizzari, Philippe; Lombès, Marc; Chanson, Philippe; Kamenický, Peter

    2016-05-01

    Germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene predispose humans to pituitary adenomas through unknown molecular mechanisms. The best-known interacting partner of AIP is the aryl hydrocarbon receptor (AhR), a transcription factor that mediates the effects of xenobiotics implicated in carcinogenesis. As 75% of AIP mutations disrupt the physical and/or functional interaction with AhR, we postulated that the tumorigenic potential of AIP mutations might result from altered AhR signaling. We evaluated the impact of AIP mutations on the AhR signaling pathway, first in fibroblasts from AIP-mutated patients with pituitary adenomas, by comparison with fibroblasts from healthy subjects, then in transfected pituitary GH3 cells. The AIP protein level in mutated fibroblasts was about half of that in cells from healthy subjects, but AhR expression was unaffected. Gene expression analyses showed significant modifications in the expression of the AhR target genes CYP1B1 and AHRR in AIP-mutated fibroblasts, both before and after stimulation with the endogenous AhR ligand kynurenine. Kynurenine increased Cyp1b1 expression to a greater extent in GH3 cells overexpressing wild type compared with cells expressing mutant AIP Knockdown of endogenous Aip in these cells attenuated Cyp1b1 induction by the AhR ligand. Both mutant AIP expression and knockdown of endogenous Aip affected the kynurenine-dependent GH secretion of GH3 cells. This study of human fibroblasts bearing endogenous heterozygous AIP mutations and transfected pituitary GH3 cells shows that AIP mutations affect the AIP protein level and alter AhR transcriptional activity in a gene- and tissue-dependent manner. © 2016 Society for Endocrinology.

  16. Crucial Role of the Aryl Hydrocarbon Receptor (AhR) in Indoxyl Sulfate-Induced Vascular Inflammation.

    PubMed

    Ito, Shunsuke; Osaka, Mizuko; Edamatsu, Takeo; Itoh, Yoshiharu; Yoshida, Masayuki

    2016-08-01

    The aryl hydrocarbon receptor (AhR), a ligand-inducible transcription factor mediating toxic effects of dioxins and uremic toxins, has recently emerged as a pathophysiological regulator of immune-inflammatory conditions. Indoxyl sulfate, a uremic toxin, is associated with cardiovascular disease in patients with chronic kidney disease and has been shown to be a ligand for AhR. The aim of this study was to investigate the potential role of AhR in indoxyl sulfate-induced leukocyte-endothelial interactions. Endothelial cell-specific AhR knockout (eAhR KO) mice were produced by crossing AhR floxed mice with Tie2 Cre mice. Indoxyl sulfate was administered for 2 weeks, followed by injection of TNF-α. Leukocyte recruitment to the femoral artery was assessed by intravital microscopy. Vascular endothelial cells were transfected with siRNA specific to AhR (siAhR) and treated with indoxyl sulfate, followed by stimulation with TNF-α. Indoxyl sulfate dramatically enhanced TNF-α-induced leukocyte recruitment to the vascular wall in control animals but not in eAhR KO mice. In endothelial cells, siAhR significantly reduced indoxyl sulfate-enhanced leukocyte adhesion as well as E-selectin expression, whereas the activation of JNK and nuclear factor-κB was not affected. A luciferase assay revealed that the region between -153 and -146 bps in the E-selectin promoter was responsible for indoxyl sulfate activity via AhR. Mutational analysis of this region revealed that activator protein-1 (AP-1) is responsible for indoxyl sulfate-triggered E-selectin expression via AhR. AhR mediates indoxyl sulfate-enhanced leukocyte-endothelial interactions through AP-1 transcriptional activity, which may constitute a new mechanism of vascular inflammation in patients with renal disease.

  17. Malformation of certain brain blood vessels caused by TCDD activation of Ahr2/Arnt1 signaling in developing zebrafish.

    PubMed

    Teraoka, Hiroki; Ogawa, Akira; Kubota, Akira; Stegeman, John J; Peterson, Richard E; Hiraga, Takeo

    2010-08-15

    2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) causes various signs of toxicity in early life stages of vertebrates through activation of the aryl hydrocarbon receptor (AHR). The AHR also plays important roles in normal development in mice, and AHR(-/-) mice show abnormal development of vascular structures in various blood vessels. Our previous studies revealed that Ahr type 2 (Ahr2) activation by TCDD and beta-naphthoflavone (BNF) caused a significant decrease in blood flow in the dorsal midbrain of zebrafish embryos. Here we report effects of TCDD exposure on the morphology of some blood vessels in the head of developing zebrafish. TCDD caused concentration-dependent anatomical rearrangements in the shape of the prosencephalic artery in zebrafish larvae. In contrast, no major vascular defects were recognized in the trunk and tail regions following exposure to TCDD at least at the concentrations used. Essentially, the same observations were also confirmed in BNF-exposed larvae. Knock-down of either Ahr2 or Ahr nuclear translocator type 1 (Arnt1) by morpholino oligonucleotides (MOs) protected larvae against abnormal shape of the prosencephalic artery caused by TCDD and BNF. On the other hand, knock-down of Ahr2 or Arnt1 in vehicle-exposed zebrafish larvae had no clear effect on morphology of the prosencephalic artery or trunk vessels. Ascorbic acid, an antioxidant, protected against the TCDD-induced decrease in blood flow through the prosencephalic artery, but not the abnormal morphological changes in the shape of this artery. These results indicate that activation of Ahr2/Arnt1 pathway by TCDD and BNF affects the shape of certain blood vessels in the brain of developing zebrafish. (c) 2010 Elsevier B.V. All rights reserved.

  18. Characterization testing of a 40 AHR bipolar nickel-hydrogen battery

    NASA Astrophysics Data System (ADS)

    Brewer, Jeffrey C.; Manzo, Michelle A.; Gemeiner, Russel P.

    1989-12-01

    Extensive characterization testing has been done on a second 40 amp-hour (Ahr), 10-cell bipolar nickel-hydrogen (Ni-H2) battery to study the effects of such operating parameters as charge and discharge rates, temperature, and pressure, on capacity, Ahr and watt-hour (Whr) efficiencies, end-of-charge (EOC) and mid-point discharge voltages. Testing to date has produced many interesting results, with the battery performing well throughout all of the test matrix except during the high-rate (5C and 10C) discharges, where poorer than expected results were observed. The exact cause of this poor performance is, as yet, unknown. Small scale 2 x 2 inch battery tests are to be used in studying this problem. Low earth orbit (LEO) cycle life testing at a 40 percent depth of discharge (DOD) and 10 C is scheduled to follow the characterization testing.

  19. Characterization testing of a 40 AHR bipolar nickel-hydrogen battery

    NASA Technical Reports Server (NTRS)

    Brewer, Jeffrey C.; Manzo, Michelle A.; Gemeiner, Russel P.

    1989-01-01

    Extensive characterization testing has been done on a second 40 amp-hour (Ahr), 10-cell bipolar nickel-hydrogen (Ni-H2) battery to study the effects of such operating parameters as charge and discharge rates, temperature, and pressure, on capacity, Ahr and watt-hour (Whr) efficiencies, end-of-charge (EOC) and mid-point discharge voltages. Testing to date has produced many interesting results, with the battery performing well throughout all of the test matrix except during the high-rate (5C and 10C) discharges, where poorer than expected results were observed. The exact cause of this poor performance is, as yet, unknown. Small scale 2 x 2 inch battery tests are to be used in studying this problem. Low earth orbit (LEO) cycle life testing at a 40 percent depth of discharge (DOD) and 10 C is scheduled to follow the characterization testing.

  20. Opioid Antagonist Impedes Exposure.

    ERIC Educational Resources Information Center

    Merluzzi, Thomas V.; And Others

    1991-01-01

    Thirty spider-phobic adults underwent exposure to 17 phobic-related, graded performance tests. Fifteen subjects were assigned to naltrexone, an opioid antagonist, and 15 were assigned to placebo. Naltrexone had a significant effect on exposure, with naltrexone subjects taking significantly longer to complete first 10 steps of exposure and with…

  1. AHR prevents human IL-1R1hi ILC3 differentiation to natural killer cells

    PubMed Central

    Hughes, Tiffany; Briercheck, Edward L.; Freud, Aharon G.; Trotta, Rossana; McClory, Susan; Scoville, Steven D.; Keller, Karen; Deng, Youcai; Cole, Jordan; Harrison, Nicholas; Mao, Charlene; Zhang, Jianying; Benson, Don M.; Yu, Jianhua; Caligiuri, Michael A.

    2014-01-01

    SUMMARY Accumulating evidence indicates that human natural killer (NK) cells develop in secondary lymphoid tissue (SLT) through a so-called “stage 3” developmental intermediate minimally characterized by a CD34-CD117+CD94- immunophenotype that lacks mature NK cell function. This stage 3 population is heterogeneous, potentially composed of functionally distinct innate lymphoid cell (ILC) types that includes interleukin-1 receptor (IL-1R1) positive, IL-22-producing ILC3s. Whether human ILC3s are developmentally related to NK cells is a subject of ongoing investigation. Here we show that antagonism of the aryl hydrocarbon receptor (AHR) or silencing of AHR gene expression promotes differentiation of tonsillar IL-22-producing IL-1R1hi human ILC3s to CD56brightCD94+ IFN-gamma-producing cytolytic mature NK cells expressing eomesodermin (EOMES) and T-Box Protein 21 (TBX21 or TBET). Hence, AHR is a transcription factor that prevents human IL-1R1hi ILC3s from differentiating into NK cells. PMID:24953655

  2. Is chronic AhR activation by rapidly metabolized ligands safe for the treatment of immune-mediated diseases?

    PubMed

    Ehrlich, Allison K; Kerkvliet, Nancy I

    2017-02-01

    There is a long standing perception that AhR ligands are automatically disqualified from pharmaceutical development due to their induction of Cyp1a1 as well as their potential for causing "dioxin-like" toxicities. However, recent discoveries of new AhR ligands with potential therapeutic applications have been reported, inviting reconsideration of this policy. One area of exploration is focused on the activation of AhR to promote the generation of regulatory T cells, which control the intensity and duration of immune responses. Rapidly metabolized AhR ligands (RMAhRLs), which do not bioaccumulate in the same manner as 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) have been discovered that induce Tregs and display impressive therapeutic efficacy in a broad range of preclinical models of immune-mediated diseases. Given the promise of these RMAhRLs, is the bias against AhR activators still valid? Can RMAhRLs be given chronically to maintain therapeutic levels of AhR activation without producing the same toxicity profile as dioxin-like compounds? Based on our review of the data, there is little evidence to support the indiscriminate exclusion of AhR activators/Cyp1a1 inducers from early drug developmental pipelines. We also found no evidence that short-term treatment with RMAhRLs produce "dioxin-like toxicity" and, in fact, were well tolerated. However, safety testing of individual RMAhRLs under therapeutic conditions, as performed with all promising new drugs, will be needed to reveal whether or not chronic activation of AhR leads to unacceptable adverse outcomes.

  3. Relationships between serum-induced AhR bioactivity or mitochondrial inhibition and circulating polychlorinated biphenyls (PCBs).

    PubMed

    Park, Wook Ha; Kang, Sora; Lee, Hong Kyu; Salihovic, Samira; Bavel, Bert van; Lind, P Monica; Pak, Youngmi Kim; Lind, Lars

    2017-08-24

    Metabolic syndrome and mitochondrial dysfunction have been linked to elevated serum levels of persistent organic pollutants (POPs). However, it is not clear which specific POPs contribute to aryl hydrocarbon receptor (AhR)-dependent bioactivity or inhibit mitochondrial function in human subjects. Here, we measured the cumulative bioactivity of AhR ligand mixture (AhR bioactivity) and the effects on mitochondrial function (ATP concentration) in recombinant Hepa1c1c7 cells incubated with raw serum samples obtained from 911 elderly subjects in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) cohort. Plasma concentrations of 30 POPs and plastic chemicals have previously been determined in the same PIVUS subjects. Linear regression analysis demonstrated that total toxic equivalence (TEQ) values and polychlorinated biphenyls (PCBs) were significantly correlated with AhR bioactivity (positively) and ATP concentration (negatively). Serum AhR bioactivities were positively associated with some PCBs, regardless of their dioxin-like properties, but only dioxin-like PCBs stimulated AhR bioactivity. By contrast, PCBs mediated a reduction in ATP content independently of their dioxin-like properties. This study suggests that AhR bioactivity and ATP concentrations in serum-treated cells may be valuable surrogate biomarkers of POP exposure and could be useful for the estimation of the effects of POPs on human health.

  4. Ablating the aryl hydrocarbon receptor (AhR) in CD11c+ cells perturbs intestinal epithelium development and intestinal immunity.

    PubMed

    Chng, Song Hui; Kundu, Parag; Dominguez-Brauer, Carmen; Teo, Wei Ling; Kawajiri, Kaname; Fujii-Kuriyama, Yoshiaki; Mak, Tak Wah; Pettersson, Sven

    2016-04-12

    Diet and microbiome derived indole derivatives are known to activate the ligand induced transcription factor, the Aryl hydrocarbon Receptor (AhR). While the current understanding of AhR biology has confirmed its role in mucosal lymphocytes, its function in intestinal antigen presenting cells (APCs) is poorly understood. Here, we report that Cre-mediated deletion of AhR in CD11c-expressing cells in C57/BL6 mice is associated with altered intestinal epithelial morphogenesis in vivo. Moreover, when co-cultured with AhR-deficient DCs ex vivo, intestinal organoids showed reduced SRY (sex determining region Y)-box 9 and increased Mucin 2 expression, which correlates with reduced Paneth cells and increased goblet cell differentiation, similar to the data obtained in vivo. Further, characterization of intestinal APC subsets, devoid of AhR, revealed an expression pattern associated with aberrant intrinsic Wnt pathway regulation. At a functional level, the loss of AhR in APCs resulted in a dysfunctional epithelial barrier, associated with a more aggressive chemically induced colitis compared to wild type animals. Our results are consistent with a model whereby the AhR signalling pathway may participate in the regulation of innate immunity through intestinal epithelium development and mucosal immunity.

  5. ITE Suppresses Angiogenic Responses in Human Artery and Vein Endothelial Cells: Differential Roles of AhR.

    PubMed

    Li, Yan; Wang, Kai; Zou, Qing-Yun; Jiang, Yi-Zhou; Zhou, Chi; Zheng, Jing

    2017-12-01

    Aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor is involved in regulation of many essential biological processes including vascular development and angiogenesis. 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) is an AhR ligand, which regulates immune responses and cancer cell growth. However, the roles of the ITE/AhR pathway in mediating placental angiogenesis remains elusive. Here, we determined if ITE affected placental angiogenic responses via AhR in human umbilical vein (HUVECs) and artery endothelial (HUAECs) cells in vitro. We observed that ITE dose- and time-dependently inhibited proliferation and viability of HUAECs and HUVECs, whereas it inhibited migration of HUAECs, but not HUVECs. While AhR siRNA significantly suppressed AhR protein expression in HUVECs and HUAECs, it attenuated the ITE-inhibited angiogenic responses of HUAECs, but not HUVECs. Collectively, ITE suppressed angiogenic responses of HUAECs and HUVECs, dependent and independent of AhR, respectively. These data suggest that ITE may regulate placental angiogenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. An Assessment of Technical and Production Risks of Candidate Low-Cost Attitude/Heading Reference Systems(AHRS)

    NASA Technical Reports Server (NTRS)

    Yuchnovicz, Daniel; Burgess, Malcolm; Hammers, William

    1999-01-01

    This report provides an assessment of technical and production risks of candidate low-cost attitude/heading reference systems (AHRS) for use in the Advanced General Aviation Transport Experiments (AGATE) airplanes. A low-cost AHRS is a key component of modem "glass cockpit" flight displays for General Aviation (GA) aircraft. The technical capabilities of several candidate low-cost AHRS were examined and described along with the technical issues involved with using all solid-state components for attitude measurement. An economic model was developed which describes the expected profit, rate of return, and volume requirements for the manufacture of low-cost AHRS for GA aircraft in the 2000 to 2020 time frame. The model is the result of interviews with GA airframe manufacturers, avionics manufacturers and historical analysis of avionics of similar complexity. The model shows that a manufacturer will break even after three years of AHRS production, realizing an 18 percent rate of return (23 percent profit) on an investment of $3.5M over the 20 year period. A start-up production estimate showed costs of $6-12M for a new company to build and certify an AHRS from scratch, considered to be a high-risk proposition, versus $0.25-0.75M for an experienced avionics manufacturer to manufacture a design under license, a low-risk proposition.

  7. High AHR expression in breast tumors correlates with expression of genes from several signaling pathways namely inflammation and endogenous tryptophan metabolism

    PubMed Central

    Castagnet, Patrice; Chemlali, Walid; Lallemand, François; Meseure, Didier; Pocard, Marc; Bieche, Ivan; Perrot-Applanat, Martine

    2018-01-01

    Increasing epidemiological and animal experimental data provide substantial support for the role of aryl hydrocarbon receptor (AhR) in mammary tumorigenesis. The effects of AhR have been clearly demonstrated in rodent models of breast carcinogenesis and in several established human breast cancer cell lines following exposure to AhR ligands or AhR overexpression. However, relatively little is known about the role of AhR in human breast cancers. AhR has always been considered to be a regulator of toxic and carcinogenic responses to environmental contaminants such as TCDD (dioxin) and benzo[a]pyrene (BaP). The aim of this study was to identify the type of breast tumors (ERα-positive or ERα-negative) that express AHR and how AhR affects human tumorigenesis. The levels of AHR, AHR nuclear translocator (ARNT) and AHR repressor (AHRR) mRNA expression were analyzed in a cohort of 439 breast tumors, demonstrating a weak association between high AHR expression and age greater than fifty years and ERα-negative status, and HR-/ERBB2 breast cancer subtypes. AHRR mRNA expression was associated with metastasis-free survival, while AHR mRNA expression was not. Immunohistochemistry revealed the presence of AhR protein in both tumor cells (nucleus and/or cytoplasm) and the tumor microenvironment (including endothelial cells and lymphocytes). High AHR expression was correlated with high expression of several genes involved in signaling pathways related to inflammation (IL1B, IL6, TNF, IL8 and CXCR4), metabolism (IDO1 and TDO2 from the kynurenine pathway), invasion (MMP1, MMP2 and PLAU), and IGF signaling (IGF2R, IGF1R and TGFB1). Two well-known ligands for AHR (TCDD and BaP) induced mRNA expression of IL1B and IL6 in an ERα-negative breast tumor cell line. The breast cancer ER status likely influences AhR activity involved in these signaling pathways. The mechanisms involved in AhR activation and target gene expression in breast cancers are also discussed. PMID:29320557

  8. High AHR expression in breast tumors correlates with expression of genes from several signaling pathways namely inflammation and endogenous tryptophan metabolism.

    PubMed

    Vacher, Sophie; Castagnet, Patrice; Chemlali, Walid; Lallemand, François; Meseure, Didier; Pocard, Marc; Bieche, Ivan; Perrot-Applanat, Martine

    2018-01-01

    Increasing epidemiological and animal experimental data provide substantial support for the role of aryl hydrocarbon receptor (AhR) in mammary tumorigenesis. The effects of AhR have been clearly demonstrated in rodent models of breast carcinogenesis and in several established human breast cancer cell lines following exposure to AhR ligands or AhR overexpression. However, relatively little is known about the role of AhR in human breast cancers. AhR has always been considered to be a regulator of toxic and carcinogenic responses to environmental contaminants such as TCDD (dioxin) and benzo[a]pyrene (BaP). The aim of this study was to identify the type of breast tumors (ERα-positive or ERα-negative) that express AHR and how AhR affects human tumorigenesis. The levels of AHR, AHR nuclear translocator (ARNT) and AHR repressor (AHRR) mRNA expression were analyzed in a cohort of 439 breast tumors, demonstrating a weak association between high AHR expression and age greater than fifty years and ERα-negative status, and HR-/ERBB2 breast cancer subtypes. AHRR mRNA expression was associated with metastasis-free survival, while AHR mRNA expression was not. Immunohistochemistry revealed the presence of AhR protein in both tumor cells (nucleus and/or cytoplasm) and the tumor microenvironment (including endothelial cells and lymphocytes). High AHR expression was correlated with high expression of several genes involved in signaling pathways related to inflammation (IL1B, IL6, TNF, IL8 and CXCR4), metabolism (IDO1 and TDO2 from the kynurenine pathway), invasion (MMP1, MMP2 and PLAU), and IGF signaling (IGF2R, IGF1R and TGFB1). Two well-known ligands for AHR (TCDD and BaP) induced mRNA expression of IL1B and IL6 in an ERα-negative breast tumor cell line. The breast cancer ER status likely influences AhR activity involved in these signaling pathways. The mechanisms involved in AhR activation and target gene expression in breast cancers are also discussed.

  9. NcoA2-Dependent Inhibition of HIF-1α Activation Is Regulated via AhR.

    PubMed

    Tsai, Chi-Hao; Li, Ching-Hao; Liao, Po-Lin; Cheng, Yu-Wen; Lin, Cheng-Hui; Huang, Shih-Hsuan; Kang, Jaw-Jou

    2015-12-01

    High endogenous levels of aryl hydrocarbon receptor (AhR) contribute to hypoxia signaling pathway inhibition following exposure to the potent AhR ligand benzo[a]pyrene (B[a]P) and could alter cellular homeostasis and disease condition. Increasing evidence indicates that AhR might compete with AhR nuclear translocator (ARNT) for complex formation with hypoxia-inducible factor-1α (HIF-1α) for transactivation, which could alter several physiological variables. Nuclear receptor coactivator 2 (NcoA2) is a transcription coactivator that regulates transcription factor activation and inhibition of basic helix-loop-helix Per (Period)-ARNT-SIM (single-minded) (bHLH-PAS) family proteins, such as HIF-1α, ARNT, and AhR, through protein-protein interactions. In this study, we demonstrated that both hypoxia and hypoxia-mimic conditions decreased NcoA2 protein expression in HEK293T cells. Hypoxia response element (HRE) and xenobiotic-responsive element (XRE) transactivation also were downregulated with NcoA2 knockdown under hypoxic conditions. In addition, B[a]P significantly decreased NcoA2 protein expression be accompanied with AhR degradation. We next evaluated whether the absence of AhR could affect NcoA2 protein function under hypoxia-mimetic conditions. NcoA2 and HIF-1α nuclear localization decreased in both B[a]P-pretreated and AhR-knockdown HepG2 cells under hypoxia-mimic conditions. Interestingly, NcoA2 overexpression downregulated HRE transactivation by competing with HIF-1α and AhR to form protein complexes with ARNT. Both NcoA2 knockdown and overexpression inhibited endothelial cell tube formation in vitro. We also demonstrated using the in vivo plug assay that NcoA2-regulated vascularization decreased in mice. Taken together, these results revealed a biphasic role of NcoA2 between AhR and hypoxic conditions, thus providing a novel mechanism underlying the cross talk between AhR and hypoxia that affects disease development and progression. © The Author 2015

  10. TCDD dysregulation of 13 AHR-target genes in rat liver

    SciTech Connect

    Watson, John D., E-mail: john.watson@oicr.on.ca; Prokopec, Stephenie D., E-mail: stephenie.prokopec@oicr.on.ca; Smith, Ashley B., E-mail: ashleyblaines@gmail.com

    2014-02-01

    Despite several decades of research, the complete mechanism by which 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other xenobiotic agonists of the aryl hydrocarbon receptor (AHR) cause toxicity remains unclear. While it has been shown that the AHR is required for all major manifestations of toxicity, the specific downstream changes involved in the development of toxic phenotypes remain unknown. Here we examine a panel of 13 genes that are AHR-regulated in many species and tissues. We profiled their hepatic mRNA abundances in two rat strains with very different sensitivities to TCDD: the TCDD-sensitive Long–Evans (Turku/AB; L–E) and the TCDD-resistant Han/Wistar (Kuopio; H/W). We evaluatedmore » doses ranging from 0 to 3000 μg/kg at 19 h after TCDD exposure and time points ranging from 1.5 to 384 h after exposure to 100 μg/kg TCDD. Twelve of 13 genes responded to TCDD in at least one strain, and seven of these showed statistically significant inter-strain differences in the time course analysis (Aldh3a1, Cyp1a2, Cyp1b1, Cyp2a1, Fmo1, Nfe2l2 and Nqo1). Cyp2s1 did not respond to TCDD in either rat strain. Five genes exhibited biphasic responses to TCDD insult (Ahrr, Aldh3a1, Cyp1b1, Nfe2l2 and Nqo1), suggesting a secondary event, such as association with additional transcriptional modulators. Of the 12 genes that responded to TCDD during the dose–response analysis, none had an ED{sub 50} equivalent to that of Cyp1a1, the most sensitive gene in this study, while nine genes responded to doses at least 10–100 fold higher, in at least one strain (Ahrr (L–E), Aldh3a1 (both), Cyp1a2 (both), Cyp1b1 (both), Cyp2a1 (L–E), Inmt (both), Nfe2l2 (L–E), Nqo1 (L–E) and Tiparp (both)). These data shed new light on the association of the AHR target genes with TCDD toxicity, and in particular the seven genes exhibiting strain-specific differences represent strong candidate mediators of Type-II toxicities. - Highlights: • NanoString measured hepatic m

  11. Deletion of Aryl Hydrocarbon Receptor AHR in Mice Leads to Subretinal Accumulation of Microglia and RPE Atrophy

    PubMed Central

    Kim, Soo-Young; Yang, Hyun-Jin; Chang, Yi-Sheng; Kim, Jung-Woong; Brooks, Matthew; Chew, Emily Y.; Wong, Wai T.; Fariss, Robert N.; Rachel, Rivka A.; Cogliati, Tiziana; Qian, Haohua; Swaroop, Anand

    2014-01-01

    Purpose. The aryl hydrocarbon receptor (AHR) is a ligand-activated nuclear receptor that regulates cellular response to environmental signals, including UV and blue wavelength light. This study was undertaken to elucidate AHR function in retinal homeostasis. Methods. RNA-seq data sets were examined for Ahr expression in the mouse retina and rod photoreceptors. The Ahr−/− mice were evaluated by fundus imaging, optical coherence tomography, histology, immunohistochemistry, and ERG. For light damage experiments, adult mice were exposed to 14,000 to 15,000 lux of diffuse white light for 2 hours. Results. In mouse retina, Ahr transcripts were upregulated during development, with continued increase in aging rod photoreceptors. Fundus examination of 3-month-old Ahr−/− mice revealed subretinal autofluorescent spots, which increased in number with age and following acute light exposure. Ahr−/− retina also showed subretinal microglia accumulation that correlated with autofluorescence changes, RPE abnormalities, and reactivity against immunoglobulin, complement factor H, and glial fibrillary acidic protein. Functionally, Ahr−/− mice displayed reduced ERG c-wave amplitudes. Conclusions. The Ahr−/− mice exhibited subretinal accumulation of microglia and focal RPE atrophy, phenotypes observed in AMD. Together with a recently published report on another Ahr−/− mouse model, our study suggests that AHR has a protective role in the retina as an environmental stress sensor. As such, its altered function may contribute to human AMD progression and provide a target for pharmacological intervention. PMID:25159211

  12. NK cells contribute to persistent airway inflammation and AHR during the later stage of RSV infection in mice.

    PubMed

    Long, Xiaoru; Xie, Jun; Zhao, Keting; Li, Wei; Tang, Wei; Chen, Sisi; Zang, Na; Ren, Luo; Deng, Yu; Xie, Xiaohong; Wang, Lijia; Fu, Zhou; Liu, Enmei

    2016-10-01

    RSV can lead to persistent airway inflammation and AHR and is intimately associated with childhood recurrent wheezing and asthma, but the underlying mechanisms remain unclear. There are high numbers of NK cells in the lung, which not only play important roles in the acute stage of RSV infection, but also are pivotal in regulating the pathogenesis of asthma. Therefore, in this study, we assumed that NK cells might contribute to persistent airway disease during the later stage of RSV infection. Mice were killed at serial time points after RSV infection to collect samples. Leukocytes in bronchoalveolar lavage fluid (BALF) were counted, lung histopathology was examined, and airway hyperresponsiveness (AHR) was measured by whole-body plethysmography. Cytokines were detected by ELISA, and NK cells were determined by flow cytometry. Rabbit anti-mouse asialo-GM-1 antibodies and resveratrol were used to deplete or suppress NK cells. Inflammatory cells in BALF, lung tissue damage and AHR were persistent for 60 days post-RSV infection. Type 2 cytokines and NK cells were significantly increased during the later stage of infection. When NK cells were decreased by the antibodies or resveratrol, type 2 cytokines, the persistent airway inflammation and AHR were all markedly reduced. NK cells can contribute to the RSV-associated persistent airway inflammation and AHR at least partially by promoting type 2 cytokines. Therefore, therapeutic targeting of NK cells may provide a novel approach to alleviating the recurrent wheezing subsequent to RSV infection.

  13. Binding Mode and Structure-Activity Relationships of ITE as an Aryl Hydrocarbon Receptor (AhR) Agonist.

    PubMed

    Dolciami, Daniela; Gargaro, Marco; Cerra, Bruno; Scalisi, Giulia; Bagnoli, Luana; Servillo, Giuseppe; Fazia, Maria Agnese Della; Puccetti, Paolo; Quintana, Francisco J; Fallarino, Francesca; Macchiarulo, Antonio

    2018-02-06

    Discovered as a modulator of the toxic response to environmental pollutants, aryl hydrocarbon receptor (AhR) has recently gained attention for its involvement in various physiological and pathological pathways. AhR is a ligand-dependent transcription factor activated by a large array of chemical compounds, which include metabolites of l-tryptophan (l-Trp) catabolism as endogenous ligands of the receptor. Among these, 2-(1'H-indole-3'-carbonyl)thiazole-4-carboxylic acid methyl ester (ITE) has attracted interest in the scientific community, being endowed with nontoxic, immunomodulatory, and anticancer AhR-mediated functions. So far, no information about the binding mode and interactions of ITE with AhR is available. In this study, we used docking and molecular dynamics to propose a putative binding mode of ITE into the ligand binding pocket of AhR. Mutagenesis studies were then instrumental in validating the proposed binding mode, identifying His 285 and Tyr 316 as important key residues for ligand-dependent receptor activation. Finally, a set of ITE analogues was synthesized and tested to further probe molecular interactions of ITE to AhR and characterize the relevance of specific functional groups in the chemical structure for receptor activity. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. The Nuclear Receptor AhR Controls Bone Homeostasis by Regulating Osteoclast Differentiation via the RANK/c-Fos Signaling Axis.

    PubMed

    Izawa, Takashi; Arakaki, Rieko; Mori, Hiroki; Tsunematsu, Takaaki; Kudo, Yasusei; Tanaka, Eiji; Ishimaru, Naozumi

    2016-12-15

    The aryl hydrocarbon receptor (AhR) pathway plays a key role in receptor activator of NF-κB ligand (RANKL)-mediated osteoclastogenesis. However, the mechanism underlying the regulation of AhR expression in osteoclasts and the signaling pathway through which AhR controls osteoclastogenesis remain unclear. We found that the expression of AhR in bone marrow-derived osteoclasts was upregulated by RANKL at an earlier stage than was the expression of signature osteoclast genes such as those encoding cathepsin K and NFAT, cytoplasmic, calcineurin-dependent 1. In response to RANKL, bone marrow macrophages isolated from AhR -/- mice exhibited impaired phosphorylation of Akt and MAPK as well as NF-κB, whereas their response to M-CSF remained unchanged. Osteoclast differentiation mediated by the AhR signaling pathway was also regulated in an RANKL/c-Fos-dependent manner. Furthermore, ligand activation of AhR by the smoke toxin benzo[a]pyrene accelerated osteoclast differentiation in a receptor-dependent manner, and AhR-dependent regulation of mitochondrial biogenesis in osteoclasts was observed. Moreover, AhR -/- mice exhibited impaired bone healing with delayed endochondral ossification. Taken together, the present results suggest that the RANKL/AhR/c-Fos signaling axis plays a critical role in osteoclastogenesis, thereby identifying the potential of AhR in treating pathological, inflammatory, or metabolic disorders of the bone. Copyright © 2016 by The American Association of Immunologists, Inc.

  15. Chemokine receptor antagonists: part 2.

    PubMed

    Pease, James E; Horuk, Richard

    2009-02-01

    The first part of this two-part review discussed approaches to generating antagonists for some of the CC chemokine receptors, including CCR1, CCR2, CCR3, and CCR4. This second part of the series concludes the review by describing antagonists for CCR5, CCR8, CCR9, CXCR3, CXCR4, and promiscuous antagonists. Chemokine receptor antagonists have found mixed success as therapeutics. Although one antagonist--maraviroc, a CCR5 inhibitor to treat AIDS--has been registered as an approved drug, this is the only success so far. There have been many failures in the clinic and we discuss the idea of promiscuous receptor antagonists as an alternative approach.

  16. An Interaction of LPS and RSV Infection in Augmenting the AHR and Airway Inflammation in Mice.

    PubMed

    Zhou, Na; Li, Wei; Ren, Luo; Xie, Xiaohong; Liu, Enmei

    2017-10-01

    Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infection (LRTI) in children under 5 years of age, especially infants with severe bronchiolitis. Our preliminary clinical experiments showed that bacterial colonization was commonly observed in children with virus-induced wheezing, particularly in those with recurrent wheezing, suggesting that bacterial colonization with an accompanying viral infection may contribute to disease severity. In most cases, RSV-infected infants were colonized with pathogenic bacteria (mainly Gram-negative bacteria). LPS is the main component of Gram-negative bacteria and acts as a ligand for Toll-like receptor 4 (TLR4). Relevant studies have reported that the TLR family is crucial in mediating the link between viral components and immunologic responses to infection. Of note, TLR4 activation has been associated with disease severity during RSV infection. In the present study, we identified that LPS aggravated RSV-induced AHR and airway inflammation in BALB/c mice using an RSV coinfection model. We found that the airway inflammatory cells and cytokines present in BALF and TRIF in lung tissue play a role in inducing AHR and airway inflammation upon RSV and bacteria coinfection, which might occur through the TRIF-MMP-9-neutrophil-MMP-9 signalling pathway. These results may aid in the development of novel treatments and improve vaccine design.

  17. AhR mediates an anti-inflammatory feedback mechanism in human Langerhans cells involving FcεRI and IDO.

    PubMed

    Koch, S; Stroisch, T J; Vorac, J; Herrmann, N; Leib, N; Schnautz, S; Kirins, H; Förster, I; Weighardt, H; Bieber, T

    2017-11-01

    Aryl hydrocarbon receptor (AhR), an important regulator of immune responses, is activated by UVB irradiation in the skin. Langerhans cells (LC) in the epidermis of patients with atopic dermatitis (AD) carry the high-affinity receptor for IgE, FcεRI, and are crucially involved in the pathogenesis of AD by inducing inflammatory responses and regulating tolerogenic processes. We investigated AhR and AhR repressor (AhRR) expression and functional consequences of AhR activation in human ex vivo skin cells and in in vitro-generated LC. Epidermal cells from healthy skin were analyzed for their expression of AhR and AhRR. LC generated from CD34 + hematopoietic stem cells (CD34LC) were treated with the UV photoproduct and AhR ligand 6-formylindolo[3,2-b]carbazole (FICZ). Cell surface receptors, transcription factors, and the tolerogenic tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO) were analyzed using flow cytometry and quantitative PCR. Epidermal LC and CD34LC express AhR and AhRR. AhR was also found in keratinocytes, which lack AhRR. AhR activation of LC by FICZ caused downregulation of FcεRI in CD34LC without affecting their maturation. AhR-mediated regulation of FcεRI did not involve any known transcription factors related to this receptor. Furthermore, we could show upregulation of IDO mediated by AhR engagement. Our study shows that AhR activation by FICZ reduces FcεRI and upregulates IDO expression in LC. This AhR-mediated anti-inflammatory feedback mechanism may dampen the allergen-induced inflammation in AD. © 2017 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.

  18. AHR and CYP1A expression link historical contamination events to modern day developmental effects in the American alligator.

    PubMed

    Hale, Matthew D; Galligan, Thomas M; Rainwater, Thomas R; Moore, Brandon C; Wilkinson, Philip M; Guillette, Louis J; Parrott, Benjamin B

    2017-11-01

    The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that initiates a transcriptional pathway responsible for the expression of CYP1A subfamily members, key to the metabolism of xenobiotic compounds. Toxic planar halogenated aromatic hydrocarbons, including dioxin and PCBs, are capable of activating the AHR, and while dioxin and PCB inputs into the environment have been dramatically curbed following strict regulatory efforts in the United States, they persist in the environment and exposures remain relevant today. Little is known regarding the effects that long-term chronic exposures to dioxin or dioxin-like compounds might have on the development and subsequent health of offspring from exposed individuals, nor is much known regarding AHR expression in reptilians. Here, we characterize AHR and CYP1A gene expression in embryonic and juvenile specimen of a long-lived, apex predator, the American alligator (Alligator mississippiensis), and investigate variation in gene expression profiles in offspring collected from sites conveying differential exposures to environmental contaminants. Both age- and tissue-dependent patterning of AHR isoform expression are detected. We characterize two downstream transcriptional targets of the AHR, CYP1A1 and CYP1A2, and describe conserved elements of their genomic architecture. When comparisons across different sites are made, hepatic expression of CYP1A2, a direct target of the AHR, appears elevated in embryos from a site associated with a dioxin point source and previously characterized PCB contamination. Elevated CYP1A2 expression is not persistent, as site-specific variation was absent in juveniles originating from field-collected eggs but reared under lab conditions. Our results illustrate the patterning of AHR gene expression in a long-lived environmental model species, and indicate a potential contemporary influence of historical contamination. This research presents a novel opportunity to link

  19. Dioxin induces Ahr-dependent robust DNA demethylation of the Cyp1a1 promoter via Tdg in the mouse liver.

    PubMed

    Amenya, Hesbon Z; Tohyama, Chiharu; Ohsako, Seiichiroh

    2016-10-07

    The aryl hydrocarbon receptor (Ahr) is a highly conserved nuclear receptor that plays an important role in the manifestation of toxicity induced by polycyclic aromatic hydrocarbons. As a xenobiotic sensor, Ahr is involved in chemical biotransformation through activation of drug metabolizing enzymes. The activated Ahr cooperates with coactivator complexes to induce epigenetic modifications at target genes. Thus, it is conceivable that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent Ahr ligand, may elicit robust epigenetic changes in vivo at the Ahr target gene cytochrome P450 1a1 (Cyp1a1). A single dose of TCDD administered to adult mice induced Ahr-dependent CpG hypomethylation, changes in histone modifications, and thymine DNA glycosylase (Tdg) recruitment at the Cyp1a1 promoter in the liver within 24 hrs. These epigenetic changes persisted until 40 days post-TCDD treatment and there was Cyp1a1 mRNA hyperinduction upon repeat administration of TCDD at this time-point. Our demethylation assay using siRNA knockdown and an in vitro methylated plasmid showed that Ahr, Tdg, and the ten-eleven translocation methyldioxygenases Tet2 and Tet3 are required for the TCDD-induced DNA demethylation. These results provide novel evidence of Ahr-driven active DNA demethylation and epigenetic memory. The epigenetic alterations influence response to subsequent chemical exposure and imply an adaptive mechanism to xenobiotic stress.

  20. Dioxin induces Ahr-dependent robust DNA demethylation of the Cyp1a1 promoter via Tdg in the mouse liver

    NASA Astrophysics Data System (ADS)

    Amenya, Hesbon Z.; Tohyama, Chiharu; Ohsako, Seiichiroh

    2016-10-01

    The aryl hydrocarbon receptor (Ahr) is a highly conserved nuclear receptor that plays an important role in the manifestation of toxicity induced by polycyclic aromatic hydrocarbons. As a xenobiotic sensor, Ahr is involved in chemical biotransformation through activation of drug metabolizing enzymes. The activated Ahr cooperates with coactivator complexes to induce epigenetic modifications at target genes. Thus, it is conceivable that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent Ahr ligand, may elicit robust epigenetic changes in vivo at the Ahr target gene cytochrome P450 1a1 (Cyp1a1). A single dose of TCDD administered to adult mice induced Ahr-dependent CpG hypomethylation, changes in histone modifications, and thymine DNA glycosylase (Tdg) recruitment at the Cyp1a1 promoter in the liver within 24 hrs. These epigenetic changes persisted until 40 days post-TCDD treatment and there was Cyp1a1 mRNA hyperinduction upon repeat administration of TCDD at this time-point. Our demethylation assay using siRNA knockdown and an in vitro methylated plasmid showed that Ahr, Tdg, and the ten-eleven translocation methyldioxygenases Tet2 and Tet3 are required for the TCDD-induced DNA demethylation. These results provide novel evidence of Ahr-driven active DNA demethylation and epigenetic memory. The epigenetic alterations influence response to subsequent chemical exposure and imply an adaptive mechanism to xenobiotic stress.

  1. The aryl hydrocarbon receptor suppresses osteoblast proliferation and differentiation through the activation of the ERK signaling pathway

    SciTech Connect

    Yu, Haitao; Du, Yuxuan; Zhang, Xulong

    Ahr activation is known to be associated with synovitis and exacerbated rheumatoid arthritis (RA), but its contributions to bone loss have not been completely elucidated. Osteoblast proliferation and differentiation are abnormal at the erosion site in RA. Here, we reported that the expression of Ahr was increased in the hind paws' bone upon collagen-induced arthritis (CIA) in mice, and the levels of Ahr were negatively correlated with bone mineral density (BMD). In addition, immunofluorescent staining showed that the high expression of Ahr was mainly localized in osteoblasts from the CIA mice compared to normal controls. Moreover, the luciferase intensity ofmore » Ahr in the nucleus increased by 12.5% in CIA osteoblasts compared to that in normal controls. In addition, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) activation of the Ahr inhibited pre-osteoblast MC3T3-E1 cellular proliferation and differentiation in a dose-dependent manner. Interestingly, the levels of alkaline phosphatase (ALP) mRNA expression in the osteoblasts of CIA mice were reduced compared to normal controls. In contrast, decreased ALP expression by activated Ahr was completely reversed after pretreatment with an Ahr inhibitor (CH-223191) in MC3T3-E1 cell lines and primary osteoblasts on day 5. Our data further showed that activation of Ahr promoted the phosphorylation of ERK after 5 days. Moreover, Ahr-dependent activation of the ERK signaling pathway decreased the levels of proliferation cells and inhibited ALP activity in MC3T3-E1 cells. These results demonstrated that the high expression of Ahr may suppress osteoblast proliferation and differentiation through activation of the ERK signaling pathway, further enabling bone erosion in CIA mice. - Highlights: • The upregulation of Ahr was localized in osteoblasts of CIA mice. • The overexpression of Ahr suppressed osteoblast development. • The Ahr activated ERK signaling pathway to exacerbate bone erosion.« less

  2. Effect of PCB 126 on aryl hydrocarbon receptor 1 (AHR1) and AHR1 nuclear translocator 1 (ARNT1) mRNA expression and CYP1 monooxygenase activity in chicken (Gallus domesticus) ovarian follicles.

    PubMed

    Wójcik, Dagmara; Antos, Piotr A; Katarzyńska, Dorota; Hrabia, Anna; Sechman, Andrzej

    2015-12-03

    The aim of the experiment was to study the in vitro effect of 3,3',4,4',5-pentachlorobiphenyl (PCB 126; a coplanar PCB congener) on aryl hydrocarbon receptor (AHR1) and AHR1 nuclear translocator (ARNT1) mRNA expression and the activity of CYP1 family monooxygenases in chicken ovarian follicles. White (1-4 mm) and yellowish (4-8 mm) prehierarchical follicles as well as fragments of the theca and granulosa layers of the 3 largest preovulatory follicles (F3-F1) were incubated in a medium supplemented with 0 (control group), 1, 10 or 100 nM PCB 126. The incubation was carried out for 6 h or 24 h for determination of mRNA expression of AHR1 and ARNT1 genes (real-time qPCR) and CYP1 monooxygenase activity (EROD and MROD fluorometric assays), respectively. It was found that chicken ovarian follicles express mRNA of AHR1 and ARNT1 genes. A modulatory effect of PCB 126 on AHR1 and ARNT1 expression depended not only on the biphenyl concentration but also on the follicular layer and the maturational state of the follicle. EROD and MROD activities appeared predominantly in the granulosa layer of the yellow preovulatory follicles. PCB 126 induced these activities in a dose-dependent manner in all ovarian follicles. The obtained results suggest that ovarian follicles, especially the granulosa layer, are involved in the detoxification process of PCBs in the laying hen. Taking this finding into consideration it can be suggested that the granulosa layer of the yellow hierarchical follicles plays a key role in the protective mechanism which reduces the amount of transferred dioxin-like compounds into the yolk of the oocyte. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  3. Genetic and epigenetic regulation of AHR gene expression in MCF-7 breast cancer cells: role of the proximal promoter GC-rich region

    PubMed Central

    Englert, Neal A.; Turesky, Robert J.; Han, Weiguo; Bessette, Erin E.; Spivack, Simon D.; Caggana, Michele; Spink, David C.; Spink, Barbara C.

    2014-01-01

    The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, contributes to carcinogenesis through its role in the regulation of cytochrome P450 1 (CYP1)-catalyzed metabolism of carcinogens. Here, we investigated genetic and epigenetic mechanisms that affect AhR expression. Analyses of the human AHR proximal promoter in MCF-7 human breast cancer cells using luciferase assays and electrophoretic mobility shift assays revealed multiple specificity protein (Sp) 1 binding sequences that are transcriptional activators in vitro. The regulation of AhR expression was evaluated in long-term estrogen exposed (LTEE) MCF-7 cells, which showed increased AhR expression, enhanced CYP1 inducibility, and increased capacity to form DNA adducts when exposed to the dietary carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine. The increased AhR expression in LTEE cells was found not to result from increased mRNA stability, differential RNA processing, or decreased DNA methylation. Analysis of the AHR proximal promoter region using chromatin immunoprecipitation confirmed that enhanced expression of AhR in LTEE cells involves changes in histone modifications, notably decreased trimethylation of histone 3, lysine 27. Upon further examination of the GC-rich Sp1-binding region, we confirmed that it contains a polymorphic (GGGGC)n repeat. In a population of newborns from New York State, the allele frequency of (GGGGC)n was n = 4>5≫6, 2. Circular dichroism spectroscopy revealed the ability of sequences of this GC-rich region to form guanine-quadruplex structures in vitro. These studies revealed multiple levels at which AhR expression may be controlled, and offer additional insights into mechanisms regulating AhR expression that can ultimately impact carcinogenesis. PMID:22728919

  4. The Role of AhR in Autoimmune Regulation and Its Potential as a Therapeutic Target against CD4 T Cell Mediated Inflammatory Disorder

    PubMed Central

    Zhu, Conghui; Xie, Qunhui; Zhao, Bin

    2014-01-01

    AhR has recently emerged as a critical physiological regulator of immune responses affecting both innate and adaptive systems. Since the AhR signaling pathway represents an important link between environmental stimulators and immune-mediated inflammatory disorder, it has become the object of great interest among researchers recently. The current review discusses new insights into the mechanisms of action of a select group of inflammatory autoimmune diseases and the ligand-activated AhR signaling pathway. Representative ligands of AhR, both exogenous and endogenous, are also reviewed relative to their potential use as tools for understanding the role of AhR and as potential therapeutics for the treatment of various inflammatory autoimmune diseases, with a focus on CD4 helper T cells, which play important roles both in self-immune tolerance and in inflammatory autoimmune diseases. Evidence indicating the potential use of these ligands in regulating inflammation in various diseases is highlighted, and potential mechanisms of action causing immune system effects mediated by AhR signaling are also discussed. The current review will contribute to a better understanding of the role of AhR and its signaling pathway in CD4 helper T cell mediated inflammatory disorder. Considering the established importance of AhR in immune regulation and its potential as a therapeutic target, we also think that both further investigation into the molecular mechanisms of immune regulation that are mediated by the ligand-specific AhR signaling pathway, and integrated research and development of new therapeutic drug candidates targeting the AhR signaling pathway should be pursued urgently. PMID:24905409

  5. AhR and SHP regulate phosphatidylcholine and S-adenosylmethionine levels in the one-carbon cycle.

    PubMed

    Kim, Young-Chae; Seok, Sunmi; Byun, Sangwon; Kong, Bo; Zhang, Yang; Guo, Grace; Xie, Wen; Ma, Jian; Kemper, Byron; Kemper, Jongsook Kim

    2018-02-07

    Phosphatidylcholines (PC) and S-adenosylmethionine (SAM) are critical determinants of hepatic lipid levels, but how their levels are regulated is unclear. Here, we show that Pemt and Gnmt, key one-carbon cycle genes regulating PC/SAM levels, are downregulated after feeding, leading to decreased PC and increased SAM levels, but these effects are blunted in small heterodimer partner (SHP)-null or FGF15-null mice. Further, aryl hydrocarbon receptor (AhR) is translocated into the nucleus by insulin/PKB signaling in the early fed state and induces Pemt and Gnmt expression. This induction is blocked by FGF15 signaling-activated SHP in the late fed state. Adenoviral-mediated expression of AhR in obese mice increases PC levels and exacerbates steatosis, effects that are blunted by SHP co-expression or Pemt downregulation. PEMT, AHR, and PC levels are elevated in simple steatosis patients, but PC levels are robustly reduced in steatohepatitis-fibrosis patients. This study identifies AhR and SHP as new physiological regulators of PC/SAM levels.

  6. Screening a mouse liver gene expression Compendium Identifies Effectors of the Aryl Hydrocarbon receptor (AhR)

    EPA Science Inventory

    The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the biological and toxic effects of 2,3, 7 ,8-tetrachlorodibenzo-p-dioxin {TCDD), dioxin-like compounds (DLC) as well as some drugs and endogenous tryptophan metabolites. Short-term act...

  7. Analysis of the AHR gene proximal promoter GGGGC-repeat polymorphism in lung, breast, and colon cancer

    SciTech Connect

    Spink, Barbara C.; Bloom, Michael S.; Wu, Susan

    The aryl hydrocarbon receptor (AhR) regulates expression of numerous genes, including those of the CYP1 gene family. With the goal of determining factors that control AHR gene expression, our studies are focused on the role of the short tandem repeat polymorphism, (GGGGC){sub n}, located in the proximal promoter of the human AHR gene. When luciferase constructs containing varying GGGGC repeats were transfected into cancer cell lines derived from the lung, colon, and breast, the number of GGGGC repeats affected AHR promoter activity. The number of GGGGC repeats was determined in DNA from 327 humans and from 38 samples representing 5more » species of non-human primates. In chimpanzees and 3 species of macaques, only (GGGGC){sub 2} alleles were observed; however, in western gorilla, (GGGGC){sub n} alleles with n = 2, 4, 5, 6, 7, and 8 were identified. In all human populations examined, the frequency of (GGGGC){sub n} was n = 4 > 5 ≫ 2, 6. When frequencies of the (GGGGC){sub n} alleles in DNA from patients with lung, colon, or breast cancer were evaluated, the occurrence of (GGGGC){sub 2} was found to be 8-fold more frequent among lung cancer patients in comparison with its incidence in the general population, as represented by New York State neonates. Analysis of matched tumor and non-tumor DNA samples from the same individuals provided no evidence of microsatellite instability. These studies indicate that the (GGGGC){sub n} short tandem repeats are inherited, and that the (GGGGC){sub 2} allele in the AHR proximal promoter region should be further investigated with regard to its potential association with lung cancer susceptibility. - Highlights: • The AHR proximal promoter contains a polymorphism, (GGGGC){sub n}, where n = 4 > 5 ≫ 2, 6 • Matched tumor and non-tumor DNA did not show (GGGGC){sub n} microsatellite instability • AHR promoter activity of a construct with (GGGGC){sub 2} was lower than that of (GGGGC){sub 4} • The frequency of (GGGGC){sub 2

  8. In Vitro Antitumor Effects of AHR Ligands Aminoflavone (AFP 464) and Benzothiazole (5F 203) in Human Renal Carcinoma Cells.

    PubMed

    Luzzani, Gabriela A; Callero, Mariana A; Kuruppu, Anchala I; Trapani, Valentina; Flumian, Carolina; Todaro, Laura; Bradshaw, Tracey D; Loaiza Perez, Andrea I

    2017-12-01

    We investigated activity and mechanism of action of two AhR ligand antitumor agents, AFP 464 and 5F 203 on human renal cancer cells, specifically examining their effects on cell cycle progression, apoptosis, and migration. TK-10, SN12C, Caki-1, and ACHN human renal cancer cell lines were treated with AFP 464 and 5F 203. We evaluated cytotoxicity by MTS assays, cell cycle arrest, and apoptosis by flow cytometry and corroborated a mechanism of action involving AhR signal transduction activation. Changes in migration properties by wound healing assays were investigated: 5F 203-sensitive cells show decreased migration after treatment, therefore, we measured c-Met phosphorylation by Western blot in these cells. A 5F 203 induced a decrease in cell viability which was more marked than AFP 464. This cytotoxicity was reduced after treatment with the AhR inhibitor α-NF for both compounds indicating AhR signaling activation plays a role in the mechanism of action. A 5F 203 is sequestered by TK-10 cells and induces CYP1A1 expression; 5F 203 potently inhibited migration of TK-10, Caki-1, and SN12C cells, and inhibited c-Met receptor phosphorylation in TK-10 cells. AhR ligand antitumor agents AFP 464 and 5F 203 represent potential new candidates for the treatment of renal cancer. A 5F 203 only inhibited migration of sensitive cells and c-Met receptor phosphorylation in TK-10 cells. c-Met receptor signal transduction is important in migration and metastasis. Therefore, we consider that 5F 203 offers potential for the treatment of metastatic renal carcinoma. J. Cell. Biochem. 118: 4526-4535, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  9. TCDD promoted EMT of hFPECs via AhR, which involved the activation of EGFR/ERK signaling

    SciTech Connect

    Gao, Zhan; The Fifth Affiliated Hospital, Zhengzhou University, 450052; Bu, Yongjun

    2016-05-01

    One critical step of second palatal fusion is the newly formed medial epithelia seam (MES) disintegration, which involves apoptosis, epithelial to mesenchymal transition (EMT), and cell migration. Although the environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) produces cleft palate at high rates, little is known about the effects of TCDD exposure on the fate of palatal epithelial cells. By using primary epithelial cells isolated from human fetal palatal shelves (hFPECs), we show that TCDD increased cell proliferation and EMT, as demonstrated by increased the epithelial markers (E-cadherin and cytokeratin14) and enhanced the mesenchymal markers (vimentin and fibronectin), but had no effect on cellmore » migration and apoptosis. TCDD exposure led to a dose-dependent increase in Slug protein expression. Coimmunoprecipitation revealed that TCDD promoted AhR to form a protein complex with Slug. ChIP assay confirmed that TCDD exposure recruited AhR to the xenobiotic responsive element of Slug promoter. Knockdown of AhR by siRNA remarkably weakened TCDD-induced binding of AhR to the XRE promoter of slug, thereby suppressed TCDD-induced vimentin. Further experiment showed that TCDD stimulated EGFR phosphorylation did not influence the TGFβ3/Smad signaling; whereas TCDD increased phosphorylation of ERK1/2 and p38 with no effect on activation of JNK. By using varieties of inhibitors, we confirmed that TCDD promoted proliferation and EMT of hFPECs via activation of EGFR/ERK pathway. These data make a novel contribution to the molecular mechanism of cleft palate by TCDD. - Highlights: • TCDD exposure promoted cell proliferation and EMT of hFPECs; • AhR signaling was activated and required for TCDD-induced EMT; • TCDD-mediated EMT of hFPECs involved the activation of EGFR/ERK signaling; • TCDD exposure had no effect on TGFβ3/Smad pathway.« less

  10. Aldosterone antagonists in heart failure.

    PubMed

    Miller, Susan E; Alvarez, René J

    2013-01-01

    Chronic, systolic heart failure is an increasing and costly health problem, and treatments based on pathophysiology have evolved that include the use of aldosterone antagonists. Advances in the understanding of neurohormonal responses to heart failure have led to better pharmacologic treatments. The steroid hormone aldosterone has been associated with detrimental effects on the cardiovascular system, such as ventricular remodeling and endothelial dysfunction. This article will review the literature and guidelines that support the use of aldosterone antagonists in the treatment of chronic, systolic heart failure. Aldosterone antagonists are life-saving drugs that have been shown to decrease mortality in patients with New York Heart Association class III to IV heart failure and in patients with heart failure after an acute myocardial infarction. Additional studies are being conducted to determine if the role of aldosterone antagonists can be expanded to patients with less severe forms of heart failure. Aldosterone antagonists are an important pharmacologic therapy in the neurohormonal blockade necessary in the treatment of systolic heart failure. These drugs have been shown to decrease mortality and reduce hospital readmission rates. The major complication of aldosterone antagonists is hyperkalemia, which can be avoided with appropriate patient selection and diligent monitoring.

  11. The AhR Ligand, TCDD, Regulates Androgen Receptor Activity Differently in Androgen-Sensitive versus Castration-Resistant Human Prostate Cancer Cells.

    PubMed

    Ghotbaddini, Maryam; Powell, Joann B

    2015-07-06

    The reported biological effects of TCDD include induction of drug metabolizing enzymes, wasting syndrome and tumor promotion. TCDD elicits most of its effects through binding the aryl hydrocarbon receptor (AhR). TCDD induced degradation of AhR has been widely reported and requires ubiquitination of the protein. The rapid depletion of AhR following TCDD activation serves as a mechanism to modulate AhR mediated gene induction. In addition to inducing AhR degradation, TCDD has been reported to induce degradation of hormone receptors. The studies reported here, evaluate the effect of TCDD exposure on androgen receptor (AR) expression and activity in androgen-sensitive LNCaP and castration-resistant C4-2 prostate cancer cells. Our results show that TCDD exposure does not induce AhR or AR degradation in C4-2 cells. However, both AhR and AR are degraded in LNCaP cells following TCDD exposure. In addition, TCDD enhances AR phosphorylation and induces expression of AR responsive genes in LNCaP cells. Our data reveals that TCDD effect on AR expression and activity differs in androgen-sensitive and castration-resistant prostate cancer cell models.

  12. The Nuclear Receptor AhR Controls Bone Homeostasis by Regulating Osteoclast Differentiation via the RANK/c-Fos Signaling Axis

    PubMed Central

    Izawa, Takashi; Arakaki, Rieko; Mori, Hiroki; Tsunematsu, Takaaki; Kudo, Yasusei; Tanaka, Eiji

    2016-01-01

    The aryl hydrocarbon receptor (AhR) pathway plays a key role in receptor activator of NF-κB ligand (RANKL)–mediated osteoclastogenesis. However, the mechanism underlying the regulation of AhR expression in osteoclasts and the signaling pathway through which AhR controls osteoclastogenesis remain unclear. We found that the expression of AhR in bone marrow–derived osteoclasts was upregulated by RANKL at an earlier stage than was the expression of signature osteoclast genes such as those encoding cathepsin K and NFAT, cytoplasmic, calcineurin-dependent 1. In response to RANKL, bone marrow macrophages isolated from AhR−/− mice exhibited impaired phosphorylation of Akt and MAPK as well as NF-κB, whereas their response to M-CSF remained unchanged. Osteoclast differentiation mediated by the AhR signaling pathway was also regulated in an RANKL/c-Fos–dependent manner. Furthermore, ligand activation of AhR by the smoke toxin benzo[a]pyrene accelerated osteoclast differentiation in a receptor-dependent manner, and AhR-dependent regulation of mitochondrial biogenesis in osteoclasts was observed. Moreover, AhR−/− mice exhibited impaired bone healing with delayed endochondral ossification. Taken together, the present results suggest that the RANKL/AhR/c-Fos signaling axis plays a critical role in osteoclastogenesis, thereby identifying the potential of AhR in treating pathological, inflammatory, or metabolic disorders of the bone. PMID:27849171

  13. [Vitamin K antagonists overdose].

    PubMed

    Groszek, Barbara; Piszczek, Paweł

    2015-01-01

    Nowadays, anticoagulant therapy belongs to the most commonly used forms of pharmacotherapy in modern medicine. The most important representatives of anticoagulants are heparins (unfractionated heparin and low-molecular-weight heparin) and coumarin derivatives (vitamin K antagonists--VKA). Next to the many advantages of traditional oral anticoagulants may also have disadvantages. In Poland most often used two VKA: acenocoumarol and warfarin. The aim of the work is the analysis of the causes of the occurrence of bleeding disorders and symptoms of overdose VKA in patients to be hospitalized. In the years 2012 to 2014 were hospitalized 62 patients with overdose VKA (40 women and 22 men). The average age of patients was 75.3 years) and clotting disturbances and/or bleeding. At the time of the admission in all patients a significant increase in the value of the INR was stated, in 22 patients INR result was " no clot detected", on the remaining value of the INR were in the range of 7 to 13.1. On 51 patients observed different severe symptoms of bleeding (hematuria, bleeding from mucous membranes of the nose or gums ecchymoses on the extremities, bleeding from the gastrointestinal tract--as in 5 patients has led to significant anemia and transfusion of concentrated red blood cells. Up on 33 patients kidney function disorder were found--exacerbated chronic renal failure and urinary tract infection. 8 diagnosed inflammatory changes in the airways. On 13 patients, it was found a significant degree of neuropsychiatric disorders (dementia, cognitive impairment), which made impossible the understanding the sense of treatment and cooperation with the patient. In 6 patients the symptoms of overdose were probably dependent on the interaction with the congestants at the same time (change the preparation of anticoagulant, NSAIDs, antibiotics). In 2 cases, the overdose was a suicide attempt in nature. In addition to the above mentioned disorders, on two of those patients diagnosed

  14. Low levels of the AhR in chronic obstructive pulmonary disease (COPD)-derived lung cells increases COX-2 protein by altering mRNA stability

    PubMed Central

    Zago, Michela; Sheridan, Jared A.; Traboulsi, Hussein; Hecht, Emelia; Zhang, Yelu; Guerrina, Necola; Matthews, Jason; Nair, Parameswaran; Eidelman, David H.; Hamid, Qutayba

    2017-01-01

    Heightened inflammation, including expression of COX-2, is associated with chronic obstructive pulmonary disease (COPD) pathogenesis. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is reduced in COPD-derived lung fibroblasts. The AhR also suppresses COX-2 in response to cigarette smoke, the main risk factor for COPD, by destabilizing the Cox-2 transcript by mechanisms that may involve the regulation of microRNA (miRNA). Whether reduced AhR expression is responsible for heightened COX-2 in COPD is not known. Here, we investigated the expression of COX-2 as well as the expression of miR-146a, a miRNA known to regulate COX-2 levels, in primary lung fibroblasts derived from non-smokers (Normal) and smokers (At Risk) with and without COPD. To confirm the involvement of the AhR, AhR knock-down via siRNA in Normal lung fibroblasts and MLE-12 cells was employed as were A549-AhRko cells. Basal expression of COX-2 protein was higher in COPD lung fibroblasts compared to Normal or Smoker fibroblasts but there was no difference in Cox-2 mRNA. Knockdown of AhR in lung structural cells increased COX-2 protein by stabilizing the Cox-2 transcript. There was less induction of miR-146a in COPD-derived lung fibroblasts but this was not due to the AhR. Instead, we found that RelB, an NF-κB protein, was required for transcriptional induction of both Cox-2 and miR-146a. Therefore, we conclude that the AhR controls COX-2 protein via mRNA stability by a mechanism independent of miR-146a. Low levels of the AhR may therefore contribute to the heightened inflammation common in COPD patients. PMID:28749959

  15. Low levels of the AhR in chronic obstructive pulmonary disease (COPD)-derived lung cells increases COX-2 protein by altering mRNA stability.

    PubMed

    Zago, Michela; Sheridan, Jared A; Traboulsi, Hussein; Hecht, Emelia; Zhang, Yelu; Guerrina, Necola; Matthews, Jason; Nair, Parameswaran; Eidelman, David H; Hamid, Qutayba; Baglole, Carolyn J

    2017-01-01

    Heightened inflammation, including expression of COX-2, is associated with chronic obstructive pulmonary disease (COPD) pathogenesis. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is reduced in COPD-derived lung fibroblasts. The AhR also suppresses COX-2 in response to cigarette smoke, the main risk factor for COPD, by destabilizing the Cox-2 transcript by mechanisms that may involve the regulation of microRNA (miRNA). Whether reduced AhR expression is responsible for heightened COX-2 in COPD is not known. Here, we investigated the expression of COX-2 as well as the expression of miR-146a, a miRNA known to regulate COX-2 levels, in primary lung fibroblasts derived from non-smokers (Normal) and smokers (At Risk) with and without COPD. To confirm the involvement of the AhR, AhR knock-down via siRNA in Normal lung fibroblasts and MLE-12 cells was employed as were A549-AhRko cells. Basal expression of COX-2 protein was higher in COPD lung fibroblasts compared to Normal or Smoker fibroblasts but there was no difference in Cox-2 mRNA. Knockdown of AhR in lung structural cells increased COX-2 protein by stabilizing the Cox-2 transcript. There was less induction of miR-146a in COPD-derived lung fibroblasts but this was not due to the AhR. Instead, we found that RelB, an NF-κB protein, was required for transcriptional induction of both Cox-2 and miR-146a. Therefore, we conclude that the AhR controls COX-2 protein via mRNA stability by a mechanism independent of miR-146a. Low levels of the AhR may therefore contribute to the heightened inflammation common in COPD patients.

  16. AHR Activation Is Protective against Colitis Driven by T Cells in Humanized Mice.

    PubMed

    Goettel, Jeremy A; Gandhi, Roopali; Kenison, Jessica E; Yeste, Ada; Murugaiyan, Gopal; Sambanthamoorthy, Sharmila; Griffith, Alexandra E; Patel, Bonny; Shouval, Dror S; Weiner, Howard L; Snapper, Scott B; Quintana, Francisco J

    2016-10-25

    Existing therapies for inflammatory bowel disease that are based on broad suppression of inflammation result in variable clinical benefit and unwanted side effects. A potential therapeutic approach for promoting immune tolerance is the in vivo induction of regulatory T cells (Tregs). Here we report that activation of the aryl hydrocarbon receptor using the non-toxic agonist 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) induces human Tregs in vitro that suppress effector T cells through a mechanism mediated by CD39 and Granzyme B. We then developed a humanized murine system whereby human CD4 + T cells drive colitis upon exposure to 2,4,6-trinitrobenzenesulfonic acid and assessed ITE as a potential therapeutic. ITE administration ameliorated colitis in humanized mice with increased CD39, Granzyme B, and IL10-secreting human Tregs. These results develop an experimental model to investigate human CD4 + T responses in vivo and identify the non-toxic AHR agonist ITE as a potential therapy for promoting immune tolerance in the intestine. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  17. Concept of AHRS Algorithm Designed for Platform Independent Imu Attitude Alignment

    NASA Astrophysics Data System (ADS)

    Tomaszewski, Dariusz; Rapiński, Jacek; Pelc-Mieczkowska, Renata

    2017-12-01

    Nowadays, along with the advancement of technology one can notice the rapid development of various types of navigation systems. So far the most popular satellite navigation, is now supported by positioning results calculated with use of other measurement system. The method and manner of integration will depend directly on the destination of system being developed. To increase the frequency of readings and improve the operation of outdoor navigation systems, one will support satellite navigation systems (GPS, GLONASS ect.) with inertial navigation. Such method of navigation consists of several steps. The first stage is the determination of initial orientation of inertial measurement unit, called INS alignment. During this process, on the basis of acceleration and the angular velocity readings, values of Euler angles (pitch, roll, yaw) are calculated allowing for unambiguous orientation of the sensor coordinate system relative to external coordinate system. The following study presents the concept of AHRS (Attitude and heading reference system) algorithm, allowing to define the Euler angles.The study were conducted with the use of readings from low-cost MEMS cell phone sensors. Subsequently the results of the study were analyzed to determine the accuracy of featured algorithm. On the basis of performed experiments the legitimacy of developed algorithm was stated.

  18. 4-Nitrophenol exposure alters the AhR signaling pathway and related gene expression in the rat liver.

    PubMed

    Li, Ruonan; Song, Meiyan; Li, Zhi; Li, Yansen; Watanabe, Gen; Nagaoka, Kentaro; Taya, Kazuyoshi; Li, Chunmei

    2017-02-01

    4-Nitrophenol (PNP) is well known as an environmental endocrine disruptor. The aim of this study was to clarify the mechanism of PNP-induced liver damage and determine the regulatory involvement of the aryl hydrocarbon receptor (AhR) signaling pathway and associated gene expression. Immature male Wistar-Imamichi rats (28 days old) were randomly divided into control and PNP groups, which consisted of 1- and 3-day exposure (1 DE and 3 DE, respectively) and 3-day exposure followed by 3-day recovery (3 DE + 3 DR), groups. Each group was administered the vehicle or PNP (200 mg kg -1 body weight). The body and liver weight were significantly decreased in the 3 DE group. The mRNA expression levels of estrogen receptor-α (ERα), glutathione S-transferase (GST) and AhR exhibited a significant increase in the 1 DE group whereas, in contrast, that of cytochrome P450 (CYP) 1A1 decreased significantly in the 3 DE +3 DR group. AhR and CYP1A1 proteins were detected in the cytoplasm of hepatocytes of the 1 DE and 3 DE +3 DR groups whereas the ERα protein was found in the hepatocyte nuclei of the 1 DE and 3 DE groups. The present study demonstrates that PNP activated the AhR signaling pathway and regulated related CYP1A1 and GST gene expression in the liver. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  19. Integration of Genome-Wide Computation DRE Search, AhR ChIP-chip and Gene Expression Analyses of TCDD-Elicited Responses in the Mouse Liver

    PubMed Central

    2011-01-01

    Background The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor (TF) that mediates responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Integration of TCDD-induced genome-wide AhR enrichment, differential gene expression and computational dioxin response element (DRE) analyses further elucidate the hepatic AhR regulatory network. Results Global ChIP-chip and gene expression analyses were performed on hepatic tissue from immature ovariectomized mice orally gavaged with 30 μg/kg TCDD. ChIP-chip analysis identified 14,446 and 974 AhR enriched regions (1% false discovery rate) at 2 and 24 hrs, respectively. Enrichment density was greatest in the proximal promoter, and more specifically, within ± 1.5 kb of a transcriptional start site (TSS). AhR enrichment also occurred distal to a TSS (e.g. intergenic DNA and 3' UTR), extending the potential gene expression regulatory roles of the AhR. Although TF binding site analyses identified over-represented DRE sequences within enriched regions, approximately 50% of all AhR enriched regions lacked a DRE core (5'-GCGTG-3'). Microarray analysis identified 1,896 number of TCDD-responsive genes (|fold change| ≥ 1.5, P1(t) > 0.999). Integrating this gene expression data with our ChIP-chip and DRE analyses only identified 625 differentially expressed genes that involved an AhR interaction at a DRE. Functional annotation analysis of differentially regulated genes associated with AhR enrichment identified overrepresented processes related to fatty acid and lipid metabolism and transport, and xenobiotic metabolism, which are consistent with TCDD-elicited steatosis in the mouse liver. Conclusions Details of the AhR regulatory network have been expanded to include AhR-DNA interactions within intragenic and intergenic genomic regions. Moreover, the AhR can interact with DNA independent of a DRE core suggesting there are alternative mechanisms of AhR-mediated gene regulation. PMID:21762485

  20. Regulatory effects of dioxin-like and non-dioxin-like PCBs and other AhR ligands on the antioxidant enzymes paraoxonase 1/2/3.

    PubMed

    Shen, Hua; Robertson, Larry W; Ludewig, Gabriele

    2016-02-01

    Paraoxonase 1 (PON1), an antioxidant enzyme, is believed to play a critical role in many diseases, including cancer. PCBs are widespread environmental contaminants known to induce oxidative stress and cancer and to produce changes in gene expression of various pro-oxidant and antioxidant enzymes. Thus, it appeared of interest to explore whether PCBs may modulate the activity and/or gene expression of PON1 as well. In this study, we compared the effects of dioxin-like and non-dioxin-like PCBs and of various aryl hydrocarbon receptor (AhR) ligands on PON1 regulation and activity in male and female Sprague-Dawley rats. Our results demonstrate that (i) the non-dioxin-like PCB154, PCB155, and PCB184 significantly reduced liver and serum PON1 activities, but only in male rats; (ii) the non-dioxin-like PCB153, the most abundant PCB in many matrices, did not affect PON1 messenger RNA (mRNA) level in the liver but significantly decreased serum PON1 activity in male rats; (iii) PCB126, an AhR ligand and dioxin-like PCB, increased both PON1 activities and gene expression; and (iv) even though three tested AhR ligands induced CYP1A in several tissues to a similar extent, they displayed differential effects on the three PONs and AhR, i.e., PCB126 was an efficacious inducer of PON1, PON2, PON3, and AhR in the liver, while 3-methylcholantrene induced liver AhR and lung PON3, and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most potent AhR agonist, increased only PON3 in the lung, at the doses and exposure times used in these studies. These results show that PCBs may have an effect on the antioxidant protection by paraoxonases in exposed populations and that regulation of gene expression through AhR is highly diverse.

  1. Tapinarof Is a Natural AhR Agonist that Resolves Skin Inflammation in Mice and Humans.

    PubMed

    Smith, Susan H; Jayawickreme, Channa; Rickard, David J; Nicodeme, Edwige; Bui, Thi; Simmons, Cathy; Coquery, Christine M; Neil, Jessica; Pryor, William M; Mayhew, David; Rajpal, Deepak K; Creech, Katrina; Furst, Sylvia; Lee, James; Wu, Dalei; Rastinejad, Fraydoon; Willson, Timothy M; Viviani, Fabrice; Morris, David C; Moore, John T; Cote-Sierra, Javier

    2017-10-01

    Tapinarof (GSK2894512) is a naturally derived topical treatment with demonstrated efficacy for patients with psoriasis and atopic dermatitis, although the biologic target and mechanism of action had been unknown. We demonstrate that the anti-inflammatory properties of tapinarof are mediated through activation of the aryl hydrocarbon receptor (AhR). We show that tapinarof binds and activates AhR in multiple cell types, including cells of the target tissue-human skin. In addition, tapinarof moderates proinflammatory cytokine expression in stimulated peripheral blood CD4+ T cells and ex vivo human skin, and impacts barrier gene expression in primary human keratinocytes; both of these processes are likely to be downstream of AhR activation based on current evidence. That the anti-inflammatory properties of tapinarof derive from AhR agonism is conclusively demonstrated using the mouse model of imiquimod-induced psoriasiform skin lesions. Topical treatment of AhR-sufficient mice with tapinarof leads to compound-driven reductions in erythema, epidermal thickening, and tissue cytokine levels. In contrast, tapinarof has no impact on imiquimod-induced skin inflammation in AhR-deficient mice. In summary, these studies identify tapinarof as an AhR agonist and confirm that its efficacy is dependent on AhR. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  2. Comparison of hepatic NRF2 and AHR binding in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) treated mice demonstrates NRF2-independent PKM2 induction.

    PubMed

    Nault, Rance; Doskey, Claire M; Fader, Kelly A; Rockwell, Cheryl E; Zacharewski, Timothy R

    2018-05-11

    2,3,7,8-Tetrachlorodibenzo- p -dioxin (TCDD) induces hepatic oxidative stress following activation of the aryl hydrocarbon receptor (AhR). Our recent studies showed TCDD induced pyruvate kinase muscle isoform 2 ( Pkm2 ) as a novel antioxidant response in normal differentiated hepatocytes. To investigate cooperative regulation between nuclear factor, erythroid derived 2, like 2 ( Nrf2 ) and the AhR in the induction of Pkm2 , hepatic ChIP-seq analyses were integrated with RNA-seq time course data from mice treated with TCDD for 2 - 168h. ChIP-seq analysis 2h after TCDD treatment identified genome-wide NRF2 enrichment. Approximately 842 NRF2 enriched regions were located in the regulatory region of differentially expressed genes (DEGs) while 579 DEGs showed both NRF2 and AhR enrichment. Sequence analysis of regions with overlapping NRF2 and AhR enrichment showed over-representation of either antioxidant or dioxin response elements (ARE and DRE, respectively), although 18 possessed both motifs. NRF2 exhibited negligible enrichment within a closed Pkm chromatin region while the AhR was enriched 29-fold. Furthermore, TCDD induced Pkm2 in primary hepatocytes from wild-type and Nrf2 null mice, indicating NRF2 is not required. Although NRF2 and AhR cooperate to regulate numerous antioxidant gene expression responses, the induction of Pkm2 by TCDD is independent of ROS-mediated NRF2 activation. The American Society for Pharmacology and Experimental Therapeutics.

  3. Phenotype Refinement Strengthens the Association of AHR and CYP1A1 Genotype with Caffeine Consumption

    PubMed Central

    McMahon, George; Taylor, Amy E.; Davey Smith, George; Munafò, Marcus R.

    2014-01-01

    Two genetic loci, one in the cytochrome P450 1A1 (CYP1A1) and 1A2 (CYP1A2) gene region (rs2472297) and one near the aryl-hydrocarbon receptor (AHR) gene (rs6968865), have been associated with habitual caffeine consumption. We sought to establish whether a more refined and comprehensive assessment of caffeine consumption would provide stronger evidence of association, and whether a combined allelic score comprising these two variants would further strengthen the association. We used data from between 4,460 and 7,520 women in the Avon Longitudinal Study of Parents and Children, a longitudinal birth cohort based in the United Kingdom. Self-report data on coffee, tea and cola consumption (including consumption of decaffeinated drinks) were available at multiple time points. Both genotypes were individually associated with total caffeine consumption, and with coffee and tea consumption. There was no association with cola consumption, possibly due to low levels of consumption in this sample. There was also no association with measures of decaffeinated drink consumption, indicating that the observed association is most likely mediated via caffeine. The association was strengthened when a combined allelic score was used, accounting for up to 1.28% of phenotypic variance. This was not associated with potential confounders of observational association. A combined allelic score accounts for sufficient phenotypic variance in caffeine consumption that this may be useful in Mendelian randomization studies. Future studies may therefore be able to use this combined allelic score to explore causal effects of habitual caffeine consumption on health outcomes. PMID:25075865

  4. Deficiency in Aryl Hydrocarbon Receptor (AHR) Expression throughout Aging Alters Gene Expression Profiles in Murine Long-Term Hematopoietic Stem Cells

    PubMed Central

    Bennett, John A.; Singh, Kameshwar P.; Unnisa, Zeenath; Welle, Stephen L.; Gasiewicz, Thomas A.

    2015-01-01

    Dysregulation of hematopoietic stem cell (HSC) signaling can contribute to the development of diseases of the blood system. Lack of aryl hydrocarbon receptor (AhR) has been associated with alterations in gene expression related to HSC function and the subsequent development of a myeloproliferative disorder in aging female mice. We sorted the most primitive population of HSCs with the highest stem cell potential (Long-term, or LT-HSCs) from 18-month-old AhR-null-allele (AhR-KO) and WT mice and analyzed gene expression using microarray to determine alterations in gene expression and cell signaling networks in HSCs that could potentially contribute to the aging phenotype of AhR-KO mice. Comparisons with previous array data from 8-week old mice indicated that aging alone is sufficient to alter gene expression. In addition, a significant number of gene expression differences were observed in aged LT-HSCs that are dependent on both aging and lack of AhR. Pathway analysis of these genes revealed networks related to hematopoietic stem cell activity or function. qPCR was used to confirm the differential expression of a subset of these genes, focusing on genes that may represent novel AhR targets due to the presence of a putative AhR binding site in their upstream regulatory region. We verified differential expression of PDGF-D, Smo, Wdfy1, Zbtb37 and Zfp382. Pathway analysis of this subset of genes revealed overlap between cellular functions of the novel AhR targets and AhR itself. Lentiviral-mediated knockdown of AhR in lineage-negative hematopoietic cells was sufficient to induce changes in all five of the candidate AhR targets identified. Taken together, these data suggest a role for AhR in HSC functional regulation, and identify novel HSC AhR target genes that may contribute to the phenotypes observed in AhR-KO mice. PMID:26208102

  5. Role of Sequence Variations in AhR Gene Towards Modulating Smoking Induced Lung Cancer Susceptibility in North Indian Population: A Multiple Interaction Analysis.

    PubMed

    Budhwar, Sneha; Bahl, Charu; Sharma, Siddharth; Singh, Navneet; Behera, Digambar

    2018-05-01

    AhR, a ubiquitously expressed ligand-activated transcription factor, upon its encounter with the foreign ligands activates the transcriptional machinery of genes encoding for bio-transformation enzymes like CYP1A1 hence, mediating the metabolism of Poly aromatic hydrocarbons and nitrosamines which account for the maximally found carcinogen in cigarette smoke. Polymorphic variants of AhR play a significant role and are held responsible for disposing the individuals with greater chances of acquiring lung cancer. To study the role of AhR variants (rs2282885, rs10250822, rs7811989, rs2066853) in affect-ing lung cancer susceptibility. 297 cases and 320 controls have been genotyped using PCR-RFLP technique. In order to find out the association, unconditional logistic regression approach was used. To analyze high order in-teractions Multifactor Dimensionality Reduction and Classification and regression tree was used. Subjects carrying the variant genotype for AhR rs7811989 showed a two-fold risk (p=0.007) and a marginal risk was also seen in case of individuals carrying either single or double copy of suscep-tible allele for rs102550822 (p=0.02). Whereas the variant allele for rs2066853 showcased a strong pro-tective effect (p=0.003). SQCC individuals with mutant genotype of rs2066853 also exhibited a protec-tive effect towards lung cancer (OR=0.30, p=0.0013). The association of rs7811989 mutant genotype and rs10250822 mutant genotype was evident especially in smokers as compared to non-smokers. AhR rs2066853 showed a decreased risk in smokers with mutant genotype (p=0.002). MDR approach gave the best interaction model of AhR rs2066853 and smoking (CVC=10/10, prediction error=0.42). AhR polymorphic variations can significantly contribute towards lung cancer predisposi-tion.

  6. Constitutive IDO expression in human cancer is sustained by an autocrine signaling loop involving IL-6, STAT3 and the AHR

    PubMed Central

    Sahm, Felix; Rauschenbach, Katharina J.; Trump, Saskia; Winter, Marcus; Ott, Martina; Ochs, Katharina; Lutz, Christian; Liu, Xiangdong; Anastasov, Natasa; Lehmann, Irina; Höfer, Thomas; von Deimling, Andreas; Wick, Wolfgang; Platten, Michael

    2014-01-01

    Indoleamine-2,3-dioxygenase (IDO) inhibitors have entered clinical trials based on their ability to restore anti-tumor immunity in preclinical studies. However, the mechanisms leading to constitutive expression of IDO in human tumors are largely unknown. Here we analyzed the pathways mediating constitutive IDO expression in human cancer. IDO-positive tumor cells and tissues showed basal phosphorylation and acetylation of STAT3 as evidenced by western blotting and immunoprecipitation. Inhibition of IL-6 or STAT3 using siRNA and/or pharmacological inhibitors reduced IDO mRNA and protein expression as well as kynurenine formation. In turn, IDO enzymatic activity activated the AHR as shown by the induction of AHR target genes. IDO-mediated AHR activation induced IL-6 expression, while inhibition or knockdown of the AHR reduced IL-6 expression. IDO activity thus sustains its own expression via an autocrine AHR–IL-6–STAT3 signaling loop. Inhibition of the AHR–IL-6–STAT3 signaling loop restored T-cell proliferation in mixed leukocyte reactions performed in the presence of IDO-expressing human cancer cells. Identification of the IDO-AHR-IL-6-STAT3 signaling loop maintaining IDO expression in human cancers reveals novel therapeutic targets for the inhibition of this core pathway promoting immunosuppression of human cancers. The relevance of the IDO-AHR-IL-6-STAT3 transcriptional circuit is underscored by the finding that high expression of its members IDO, STAT3 and the AHR target gene CYP1B1 is associated with reduced relapse-free survival in lung cancer patients. PMID:24657910

  7. Narcotic antagonists. Treatment tool for addiction.

    PubMed

    Valentine, N M; Meyer, R E

    1976-09-01

    Narcotic antagonists have recently gained attention through research aimed at evaluating both biochemical effects and treatment potential for opiate addiction. Narcotic antagonists are a classification of drugs which block the euphoric (and all other) effects of opiates. Naltrexone is the most promising narcotic antagonist based on ability to produce blockade, length of duration, and relative absence of side effects. The narcotic antagonists offer an adjunctive or alternative method of treatment for opiate addicts based on Wikler's biobehavioral theory of conditioned abstinence. Narcotic antagonists are presently being investigated at seven research centers throughout the United States and may be available for clinical use in the future.

  8. TCDD, FICZ, and Other High Affinity AhR Ligands Dose-Dependently Determine the Fate of CD4+ T Cell Differentiation.

    PubMed

    Ehrlich, Allison K; Pennington, Jamie M; Bisson, William H; Kolluri, Siva K; Kerkvliet, Nancy I

    2018-02-01

    FICZ and TCDD, two high-affinity AhR ligands, are reported to have opposite effects on T cell differentiation with TCDD inducing regulatory T cells and FICZ inducing Th17 cells. This dichotomy has been attributed to ligand-intrinsic differences in AhR activation, although differences in sensitivity to metabolism complicate the issue. TCDD is resistant to AhR-induced metabolism and produces sustained AhR activation following a single dose in the μg/kg range, whereas FICZ is rapidly metabolized and AhR activation is transient. Nonetheless, prior studies comparing FICZ with TCDD have generally used the same 10-50 μg/kg dose range, and thus the two ligands would not equivalently activate AhR. We hypothesized that high-affinity AhR ligands can promote CD4+ T cell differentiation into both Th17 cells and Tregs, with fate depending on the extent and duration of AhR activation. We compared the immunosuppressive effects of TCDD and FICZ, along with two other rapidly metabolized ligands (ITE and 11-Cl-BBQ) in an acute alloresponse mouse model. The dose and timing of administration of each ligand was optimized for TCDD-equivalent Cyp1a1 induction. When optimized, all of the ligands suppressed the alloresponse in conjunction with the induction of Foxp3- Tr1 cells on day 2 and the expansion of natural Foxp3+ Tregs on day 10. In contrast, a low dose of FICZ induced transient expression of Cyp1a1 and did not induce Tregs or suppress the alloresponse but enhanced IL-17 production. Interestingly, low doses of the other ligands, including TCDD, also increased IL-17 production on day 10. These findings support the conclusion that the dose and the duration of AhR activation by high-affinity AhR ligands are the primary factors driving the fate of T cell differentiation. © The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  9. Structure of the C-terminal effector-binding domain of AhrC bound to its corepressor l-arginine

    SciTech Connect

    Garnett, James A.; Baumberg, Simon; Stockley, Peter G.

    2007-11-01

    The crystal structure of the C-terminal domain hexameric core of AhrC, with bound corepressor (l-arginine), has been solved at 1.95 Å resolution. Binding of l-arginine results in a rotation between the two trimers of the hexamer, leading to the activation of the DNA-binding state. The arginine repressor/activator protein (AhrC) from Bacillus subtilis belongs to a large family of multifunctional transcription factors that are involved in the regulation of bacterial arginine metabolism. AhrC interacts with operator sites in the promoters of arginine biosynthetic and catabolic operons, acting as a transcriptional repressor at biosynthetic sites and an activator of transcription at catabolicmore » sites. AhrC is a hexamer of identical subunits, each having two domains. The C-terminal domains form the core of the protein and are involved in oligomerization and l-arginine binding. The N-terminal domains lie on the outside of the compact core and play a role in binding to 18 bp DNA operators called ARG boxes. The C-terminal domain of AhrC has been expressed, purified and characterized, and also crystallized as a hexamer with the bound corepressor l-arginine. Here, the crystal structure refined to 1.95 Å is presented.« less

  10. Antioxidant Opuntia ficus-indica Extract Activates AHR-NRF2 Signaling and Upregulates Filaggrin and Loricrin Expression in Human Keratinocytes.

    PubMed

    Nakahara, Takeshi; Mitoma, Chikage; Hashimoto-Hachiya, Akiko; Takahara, Masakazu; Tsuji, Gaku; Uchi, Hiroshi; Yan, Xianghong; Hachisuka, Junichi; Chiba, Takahito; Esaki, Hitokazu; Kido-Nakahara, Makiko; Furue, Masutaka

    2015-10-01

    Opuntia ficus-indica (OFI) is a cactus species widely used as an anti-inflammatory, antilipidemic, and hypoglycemic agent. It has been shown that OFI extract (OFIE) inhibits oxidative stress in animal models of diabetes and hepatic disease; however, its antioxidant mechanism remains largely unknown. In this study, we demonstrated that OFIE exhibited potent antioxidant activity through the activation of nuclear factor erythroid 2-related factor 2 (NRF2) and the downstream antioxidant enzyme quinone oxidoreductase 1 (NQO1), which inhibited the generation of reactive oxygen species in keratinocytes challenged with tumor necrosis factor α or benzo[α]pyrene. The antioxidant capacity of OFIE was canceled in NRF2 knockdown keratinocytes. OFIE exerted this NRF2-NQO1 upregulation through activation of the aryl hydrocarbon receptor (AHR). Moreover, the ligation of AHR by OFIE upregulated the expression of epidermal barrier proteins: filaggrin and loricrin. OFIE also prevented TH2 cytokine-mediated downregulation of filaggrin and loricrin expression in an AHR-dependent manner because it was canceled in AHR knockdown keratinocytes. Antioxidant OFIE is a potent activator of AHR-NRF2-NQO1 signaling and may be beneficial in treating barrier-disrupted skin disorders.

  11. Opioid antagonists for smoking cessation

    PubMed Central

    David, Sean P; Lancaster, Tim; Stead, Lindsay F; Evins, A. Eden; Prochaska, Judith J

    2014-01-01

    Background The reinforcing properties of nicotine may be mediated through release of various neurotransmitters both centrally and systemically. People who smoke report positive effects such as pleasure, arousal, and relaxation as well as relief of negative affect, tension, and anxiety. Opioid (narcotic) antagonists are of particular interest to investigators as potential agents to attenuate the rewarding effects of cigarette smoking. Objectives To evaluate the efficacy of opioid antagonists in promoting long-term smoking cessation. The drugs include naloxone and the longer-acting opioid antagonist naltrexone. Search methods We searched the Cochrane Tobacco Addiction Group Specialised Register for trials of naloxone, naltrexone and other opioid antagonists and conducted an additional search of MEDLINE using ’Narcotic antagonists’ and smoking terms in April 2013. We also contacted investigators, when possible, for information on unpublished studies. Selection criteria We considered randomised controlled trials comparing opioid antagonists to placebo or an alternative therapeutic control for smoking cessation. We included in the meta-analysis only those trials which reported data on abstinence for a minimum of six months. We also reviewed, for descriptive purposes, results from short-term laboratory-based studies of opioid antagonists designed to evaluate psycho-biological mediating variables associated with nicotine dependence. Data collection and analysis We extracted data in duplicate on the study population, the nature of the drug therapy, the outcome measures, method of randomisation, and completeness of follow-up. The main outcome measure was abstinence from smoking after at least six months follow-up in patients smoking at baseline. Abstinence at end of treatment was a secondary outcome. We extracted cotinine- or carbon monoxide-verified abstinence where available. Where appropriate, we performed meta-analysis, pooling risk ratios using a Mantel

  12. Sequence variants at CYP1A1–CYP1A2 and AHR associate with coffee consumption

    PubMed Central

    Sulem, Patrick; Gudbjartsson, Daniel F.; Geller, Frank; Prokopenko, Inga; Feenstra, Bjarke; Aben, Katja K.H.; Franke, Barbara; den Heijer, Martin; Kovacs, Peter; Stumvoll, Michael; Mägi, Reedik; Yanek, Lisa R.; Becker, Lewis C.; Boyd, Heather A.; Stacey, Simon N.; Walters, G. Bragi; Jonasdottir, Adalbjorg; Thorleifsson, Gudmar; Holm, Hilma; Gudjonsson, Sigurjon A.; Rafnar, Thorunn; Björnsdottir, Gyda; Becker, Diane M.; Melbye, Mads; Kong, Augustine; Tönjes, Anke; Thorgeirsson, Thorgeir; Thorsteinsdottir, Unnur; Kiemeney, Lambertus A.; Stefansson, Kari

    2011-01-01

    Coffee is the most commonly used stimulant and caffeine is its main psychoactive ingredient. The heritability of coffee consumption has been estimated at around 50%. We performed a meta-analysis of four genome-wide association studies of coffee consumption among coffee drinkers from Iceland (n = 2680), the Netherlands (n = 2791), the Sorbs Slavonic population isolate in Germany (n = 771) and the USA (n = 369) using both directly genotyped and imputed single nucleotide polymorphisms (SNPs) (2.5 million SNPs). SNPs at the two most significant loci were also genotyped in a sample set from Iceland (n = 2430) and a Danish sample set consisting of pregnant women (n = 1620). Combining all data, two sequence variants significantly associated with increased coffee consumption: rs2472297-T located between CYP1A1 and CYP1A2 at 15q24 (P = 5.4 · 10−14) and rs6968865-T near aryl hydrocarbon receptor (AHR) at 7p21 (P = 2.3 · 10−11). An effect of ∼0.2 cups a day per allele was observed for both SNPs. CYP1A2 is the main caffeine metabolizing enzyme and is also involved in drug metabolism. AHR detects xenobiotics, such as polycyclic aryl hydrocarbons found in roasted coffee, and induces transcription of CYP1A1 and CYP1A2. The association of these SNPs with coffee consumption was present in both smokers and non-smokers. PMID:21357676

  13. Genome-Wide Meta-Analysis Identifies Regions on 7p21 (AHR) and 15q24 (CYP1A2) As Determinants of Habitual Caffeine Consumption

    PubMed Central

    Azzato, Elizabeth M.; Bennett, Siiri N.; Berndt, Sonja I.; Boerwinkle, Eric; Chanock, Stephen; Chatterjee, Nilanjan; Couper, David; Curhan, Gary; Heiss, Gerardo; Hu, Frank B.; Hunter, David J.; Jacobs, Kevin; Jensen, Majken K.; Kraft, Peter; Landi, Maria Teresa; Nettleton, Jennifer A.; Purdue, Mark P.; Rajaraman, Preetha; Rimm, Eric B.; Rose, Lynda M.; Rothman, Nathaniel; Silverman, Debra; Stolzenberg-Solomon, Rachael; Subar, Amy; Yeager, Meredith; Chasman, Daniel I.; van Dam, Rob M.; Caporaso, Neil E.

    2011-01-01

    We report the first genome-wide association study of habitual caffeine intake. We included 47,341 individuals of European descent based on five population-based studies within the United States. In a meta-analysis adjusted for age, sex, smoking, and eigenvectors of population variation, two loci achieved genome-wide significance: 7p21 (P = 2.4×10−19), near AHR, and 15q24 (P = 5.2×10−14), between CYP1A1 and CYP1A2. Both the AHR and CYP1A2 genes are biologically plausible candidates as CYP1A2 metabolizes caffeine and AHR regulates CYP1A2. PMID:21490707

  14. The aryl hydrocarbon receptor repressor - More than a simple feedback inhibitor of AhR signaling: Clues for its role in inflammation and cancer.

    PubMed

    Vogel, Christoph F A; Haarmann-Stemmann, Thomas

    2017-02-01

    The aryl hydrocarbon receptor repressor (AhRR) was first described as a specific competitive repressor of aryl hydrocarbon receptor (AhR) activity based on its ability to dimerize with the AhR nuclear translocator (ARNT) and through direct competition of AhR/ARNT and AhRR/ARNT complexes for binding to dioxin-responsive elements (DREs). Like AhR, AhRR belongs to the basic Helix-Loop-Helix/Per-ARNT-Sim (bHLH/PAS) protein family but lacks functional ligand-binding and transactivation domains. Transient transfection experiments with ARNT and AhRR mutants examining the inhibitory mechanism of AhRR suggested a more complex mechanism than the simple mechanism of negative feedback through sequestration of ARNT to regulate AhR signaling. Recently, AhRR has been shown to act as a tumor suppressor gene in several types of cancer cells. Furthermore, epidemiological studies have found epigenetic changes and silencing of AhRR associated with exposure to cigarette smoke and cancer development. Additional studies from our laboratories have demonstrated that AhRR represses other signaling pathways including NF-κB and is capable of regulating inflammatory responses. A better understanding of the regulatory mechanisms of AhRR in AhR signaling and adverse outcome pathways leading to deregulated inflammatory responses contributing to tumor promotion and other adverse health effects is expected from future studies. This review article summarizes the characteristics of AhRR as an inhibitor of AhR activity and highlights more recent findings pointing out the role of AhRR in inflammation and tumorigenesis.

  15. Novel cellular targets of AhR underlie alterations in neutrophilic inflammation and iNOS expression during influenza virus infection

    PubMed Central

    Head Wheeler, Jennifer L.; Martin, Kyle C.; Lawrence, B. Paige

    2012-01-01

    The underlying reasons for variable clinical outcomes from respiratory viral infections remain uncertain. Several studies suggest that environmental factors contribute to this variation, but limited knowledge of cellular and molecular targets of these agents hampers our ability to quantify or modify their contribution to disease and improve public health. The aryl hydrocarbon receptor (AhR) is an environment sensing transcription factor that binds many anthropogenic and natural chemicals. The immunomodulatory properties of AhR ligands are best characterized with extensive studies of changes in CD4+ T cell responses. Yet, AhR modulates other aspects of immune function. We previously showed that during influenza virus infection, AhR activation modulates neutrophil accumulation in the lung, and this contributes to increased mortality in mice. Enhanced levels of inducible nitric oxide synthase (iNOS) in infected lungs are observed during the same timeframe as AhR-mediated increased pulmonary neutrophilia. In this study, we evaluated whether these two consequences of AhR activation are causally linked. Reciprocal inhibition of AhR-mediated elevations in iNOS and pulmonary neutrophilia reveal that, although they are contemporaneous, they are not causally related. We show using Cre/loxP technology that elevated iNOS levels and neutrophil number in the infected lung result from separate, AhR-dependent signaling in endothelial and respiratory epithelial cells, respectively. Studies using mutant mice further reveal that AhR-mediated alterations in these innate responses to infection require a functional nuclear localization signal and DNA binding domain. Thus, gene targets of AhR in non-hematopoietic cells are important new considerations for understanding AhR-mediated changes in innate anti-viral immunity. PMID:23233726

  16. Effects of 4-nitrophenol on expression of the ER-α and AhR signaling pathway-associated genes in the small intestine of rats.

    PubMed

    Tang, Juan; Song, Meiyan; Watanabe, Gen; Nagaoka, Kentaro; Rui, Xiaoli; Li, ChunMei

    2016-09-01

    4-Nitrophenol (PNP) is a persistent organic pollutant that was proven to be an environmental endocrine disruptor. The aim of this study was to evaluate the role of the estrogen receptor-α (ER-α) and aryl hydrocarbon receptor (AhR) signaling pathway in regulating the damage response to PNP in the small intestine of rats. Wistar-Imamichi male rats (21 d) were randomly divided into two groups: the control group and PNP group. Each group had three processes that were gavaged with PNP or vehicle daily: single dose (1 d), repeated dose (3 consecutive days) (3 d), and repeated dose with recovery (3 consecutive days and 3 recovery days) (6 d). The weight of the body, the related viscera, and small intestine were examined. Histological parameters of the small intestine and the quantity of mucus proteins secreted by small goblet cells were determined using HE staining and PAS staining. The mRNA expression of AhR, ER-α, CYP1A1, and GST was measured by real-time qPCR. In addition, we also analyzed the AhR, ER-α, and CYP1A1 expression in the small intestine by immunohistochemical staining. The small intestines histologically changed in the PNP-treated rat and the expression of AhR, CYP1A1, and GST was increased. While ER-α was significantly decreased in the small intestine, simultaneously, when rats were exposed to a longer PNP treatment, the damages disappeared. Our results demonstrate that PNP has an effect on the expression of AhR signaling pathway genes, AhR, CYP1A1, and GST, and ER-α in the rat small intestine. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Combined chemical and toxicological long-term monitoring for AhR agonists with SPMD-based virtual organisms in drinking water Danjiangkou Reservoir, China.

    PubMed

    Wang, Jingxian; Song, Guoqiang; Li, Aimin; Henkelmann, Bernhard; Pfister, Gerd; Tong, Anthony Z; Schramm, Karl-Werner

    2014-08-01

    SPMD-based virtual organisms (VOs) were employed for time-integrating, long-term sampling combined biological and chemical analyses for exposure assessment of hydrophobic organic pollutants (HOPs) in a drinking water reservoir, China. The SPMDs were deployed at four and five sites in the Danjiangkou (DJK) reservoir over two periods of 26 and 31 d to sequester the hydrophobic contaminants in water. The chosen bioassay response for the extracts of the SPMDs, the induction of 7-ethoxyresorufin-o-deethylase (EROD) was assayed using a rat hepatoma cell line (H4IIE). The known aryl hydrocarbon receptor (AhR) agonists PAHs and PCBs were analyzed by HRGC/HRMS instrument. The cause-effect relationship between the observed AhR activities and chemical concentrations of detected AhR agonists was examined. The results show that the extracts from the SPMD samples could induce AhR activity significantly, whereas the chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQcal) was not correlated with the bioassay-derived TCDD equivalent (TEQbio). The known AhR agonists could only account for 2-10% of the observed AhR responses among which the contribution of PCBs could almost be neglected. Unidentified AhR-active compounds represented a greater proportion of the TCDD equivalent (TCDD-EQ) in SPMD samples from DJK. Based on the first assessment, the VO followed by the combination of chemical and biological analyses emerges as a resource efficient water monitoring device in ecotoxicological assessment for toxicologically relevant compounds which are readily available for uptake by resident aquatic biota in drinking water resources. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Baicalein induces G1 arrest in oral cancer cells by enhancing the degradation of cyclin D1 and activating AhR to decrease Rb phosphorylation

    SciTech Connect

    Cheng, Ya-Hsin, E-mail: yhcheng@mail.cmu.edu.tw; Li, Lih-Ann; Lin, Pinpin

    Baicalein is a flavonoid, known to have anti-inflammatory and anti-cancer effects. As an aryl hydrocarbon receptor (AhR) ligand, baicalein at high concentrations blocks AhR-mediated dioxin toxicity. Because AhR had been reported to play a role in regulating the cell cycle, we suspected that the anti-cancer effect of baicalein is associated with AhR. This study investigated the molecular mechanism involved in the anti-cancer effect of baicalein in oral cancer cells HSC-3, including whether such effect would be AhR-mediated. Results revealed that baicalein inhibited cell proliferation and increased AhR activity in a dose-dependent manner. Cell cycle was arrested at the G1 phasemore » and the expression of CDK4, cyclin D1, and phosphorylated retinoblastoma (pRb) was decreased. When the AhR was suppressed by siRNA, the reduction of pRb was partially reversed, accompanied by a decrease of cell population at G1 phase and an increase at S phase, while the reduction of cyclin D1 and CDK4 did not change. This finding suggests that the baicalein activation of AhR is indeed associated with the reduction of pRb, but is independent of the reduction of cyclin D1 and CDK4. When cells were pre-treated with LiCl, the inhibitor of GSK-3β, the decrease of cyclin D1 was blocked and the reduction of pRb was recovered. The data indicates that in HSC-3 the reduction of pRb is both mediated by baicalein through activation of AhR and facilitation of cyclin D1 degradation, which causes cell cycle arrest at the G1 phase, and results in the inhibition of cell proliferation. -- Highlights: ► Baicalein causes the G1 phase arrest by decreasing Rb phosphorylation. ► Baicalein modulates AhR-mediated cell proliferation. ► Both AhR activation and cyclin D1 degradation results in hypophosphorylation of Rb. ► Baicalein facilitates cyclin D1 degradation by signalling the GSK-3β pathway.« less

  19. The aryl hydrocarbon receptor-mediated disruption of vitellogenin synthesis in the fish liver: Cross-talk between AHR- and ERα-signalling pathways

    PubMed Central

    Bemanian, Vahid; Male, Rune; Goksøyr, Anders

    2004-01-01

    Background In the fish liver, the synthesis of egg yolk protein precursor vitellogenin (VTG) is under control of the estrogen receptor alpha (ERα). Environmental contaminants such as 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) are suspected to have antiestrogenic effects. The aryl hydrocarbon receptor (AHR) is the initial cellular target for TCDD and related compounds. The AHR is a ligand-activated transcription factor that stimulates the expression of the genes encoding xenobiotic metabolizing enzymes, such as cytochrome P450 1A (CYP1A). In this study, the effects of activation of AHR on the hepatic expression of VTG and ERα genes, in primary cultured salmon hepatocytes, have been investigated. Results The expression of the genes encoding VTG and ERα were strongly induced by 17β-estradiol (E2). However, the expression of VTG was disrupted by exposure of the cells to TCDD while CYP1A expression was enhanced. The effect of TCDD on VTG and CYP1A expression was annulled by the AHR-inhibitor α-naphthoflavone. Furthermore, exposure of the cells to TCDD abolished E2-induced accumulation of ERα mRNA. The AHR-mediated inhibitory effects on the expression of the VTG and ERα genes may occur at transcriptional and/or post-transcriptional levels. Nuclear run-off experiments revealed that simultaneous exposure of the cells to E2 and TCDD strongly inhibited the initiation of transcription of the VTG and ERα genes. In addition, inhibition of RNA synthesis by actinomycin D treatment showed that post-transcriptional levels of VTG and ERα mRNAs were not significantly altered upon treatment of the cells with TCDD. These results suggested that activation of AHR may inhibit the transactivation capacity of the ERα. Further, electrophoretic mobility shift assays using nuclear extracts prepared from cells treated for one or two hours with E2, alone or in mixture with TCDD, showed a strong reduction in the DNA binding activities upon TCDD treatment. These results also suggested

  20. USE OF THE TEQ MODEL FOR ASSESSING AHR MEDIATED TOXICITY RISKS TO POPULATIONS OF LAKE TROUT AND OTHER SPECIES IN LAKE ONTARIO

    EPA Science Inventory

    The toxicity equivalence (TEQ) model for assessing aryl hydrocarbon receptor (AHR) mediated toxicity risks associated with polyhalogenated aromatic chemicals structurally similar to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been applied to human health risks for more than 15...

  1. Effect of TBT and PAHs on CYP1A, AhR and Vitellogenin Gene Expression in the Japanese Eel, Anguilla japonica.

    PubMed

    Choi, Min Seop; Kwon, Se Ryun; Choi, Seong Hee; Kwon, Hyuk Chu

    2012-12-01

    Gene expressions of cytochrome P4501A (CYP1A), aryl hydrocarbon receptor (AhR) and vitellogenin (Vg) by endocrine disruptors, benzo[α]pyrene (B[a]P) and tributyltin (TBT) were examined in cultured eel hepatocytes which were isolated from eels treated previously with B[a]P (10 mg/kg) or estradiol-17β (20 mg/kg) in vivo, and the relationship between CYP1A, AhR and Vg genes were studied. When the cultured eel hepatocytes were treated with B[a]P (10(-6)-10(-5) M) the gene expressions of CYP1A and AhR were enhanced in a concentration-dependent manner. However, when treated with TBT (10(-9)-10(-5) M) the gene expressions of CYP1A and AhR were suppressed at high concentrations (10(-6)-10(-5) M), while having no effects at low concentrations (10(-9)-10(-7) M). Gene expression of Vg was also suppressed by TBT in a concentration-dependent manner in cultured eel hepatocytes which was previously treated in vivo with estradiol-17β.

  2. Effect of TBT and PAHs on CYP1A, AhR and Vitellogenin Gene Expression in the Japanese Eel, Anguilla japonica

    PubMed Central

    Choi, Min Seop; Kwon, Se Ryun; Choi, Seong Hee; Kwon, Hyuk Chu

    2012-01-01

    Gene expressions of cytochrome P4501A (CYP1A), aryl hydrocarbon receptor (AhR) and vitellogenin (Vg) by endocrine disruptors, benzo[α]pyrene (B[a]P) and tributyltin (TBT) were examined in cultured eel hepatocytes which were isolated from eels treated previously with B[a]P (10 mg/kg) or estradiol-17β (20 mg/kg) in vivo, and the relationship between CYP1A, AhR and Vg genes were studied. When the cultured eel hepatocytes were treated with B[a]P (10-6-10-5 M) the gene expressions of CYP1A and AhR were enhanced in a concentration-dependent manner. However, when treated with TBT (10-9-10-5 M) the gene expressions of CYP1A and AhR were suppressed at high concentrations (10-6-10-5 M), while having no effects at low concentrations (10-9-10-7 M). Gene expression of Vg was also suppressed by TBT in a concentration-dependent manner in cultured eel hepatocytes which was previously treated in vivo with estradiol-17β. PMID:25949102

  3. A high-resolution structure of the DNA-binding domain of AhrC, the arginine repressor/activator protein from Bacillus subtilis

    SciTech Connect

    Garnett, James A.; Baumberg, Simon; Stockley, Peter G.

    2007-11-01

    The structure of the winged helix–turn–helix DNA-binding domain of AhrC has been determined at 1.0 Å resolution. The largely hydrophobic β-wing shows high B factors and may mediate the dimer interface in operator complexes. In Bacillus subtilis the concentration of l-arginine is controlled by the transcriptional regulator AhrC, which interacts with 18 bp DNA operator sites called ARG boxes in the promoters of arginine biosynthetic and catabolic operons. AhrC is a 100 kDa homohexamer, with each subunit having two domains. The C-terminal domains form the core, mediating intersubunit interactions and binding of the co-repressor l-arginine, whilst the N-terminal domains containmore » a winged helix–turn–helix DNA-binding motif and are arranged around the periphery. The N-terminal domain of AhrC has been expressed, purified and characterized and it has been shown that the fragment still binds DNA operators as a recombinant monomer. The DNA-binding domain has also been crystallized and the crystal structure refined to 1.0 Å resolution is presented.« less

  4. Effects of artificial sweeteners on the AhR- and GR-dependent CYP1A1 expression in primary human hepatocytes and human cancer cells.

    PubMed

    Kamenickova, Alzbeta; Pecova, Michaela; Bachleda, Petr; Dvorak, Zdenek

    2013-12-01

    Food constituents may cause a phenomenon of food-drug interactions. In the current study, we examined the effects of artificial sweeteners (aspartame, acesulfame, cyclamate, saccharin) on the aryl hydrocarbon receptor (AhR) and glucocorticoid receptor (GR)-dependent expression of CYP1A1 in human hepatocytes, hepatic HepG2 and intestinal LS174T cancer cell lines. Sweeteners were tested in concentrations up to those occurring in non-alcoholic beverages. Basal and ligand-inducible AhR- and GR-dependent reporter gene activation in stably transfected HepG2 and HeLa cells, respectively, were not affected by either of the sweeteners tested after 24h of incubation. The expression of CYP1A1 mRNA and protein in primary cultures of human hepatocytes and in LS174T and HepG2 cells was not induced by any of the tested sweeteners. Overall, aspartame, acesulfame, saccharin and cyclamate had no effects on CYP1A1 expression and transcriptional activities of AhR and GR. These data imply the safety of artificial sweeteners in terms of interference with AhR, GR and CYP1A1. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Ahr2-dependence of PCB126 effects on the swim bladder in relation to expression of CYP1 and cox-2 genes in developing zebrafish

    SciTech Connect

    Jönsson, Maria E., E-mail: maria.jonsson@ebc.uu.se; Biology Department, Redfield 3-42 MS 32, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543; Kubota, Akira, E-mail: akubota@whoi.edu

    2012-12-01

    The teleost swim bladder is assumed a homolog of the tetrapod lung. Both swim bladder and lung are developmental targets of persistent aryl hydrocarbon receptor (AHR) agonists; in zebrafish (Danio rerio) the swim bladder fails to inflate with exposure to 3,3′,4,4′,5-pentachlorobiphenyl (PCB126). The mechanism for this effect is unknown, but studies have suggested roles of cytochrome P450 1 (CYP1) and cyclooxygenase 2 (Cox-2) in some Ahr-mediated developmental effects in zebrafish. We determined relationships between swim bladder inflation and CYP1 and Cox-2 mRNA expression in PCB126-exposed zebrafish embryos. We also examined effects on β-catenin dependent transcription, histological effects, and Ahr2 dependencemore » of the effect of PCB126 on swim bladder using morpholinos targeting ahr2. One-day-old embryos were exposed to waterborne PCB126 or carrier (DMSO) for 24 h and then held in clean water until day 4, a normal time for swim bladder inflation. The effects of PCB126 were concentration-dependent with EC{sub 50} values of 1.4 to 2.0 nM for induction of the CYP1s, 3.7 and 5.1 nM (or higher) for cox-2a and cox-2b induction, and 2.5 nM for inhibition of swim bladder inflation. Histological defects included a compaction of the developing bladder. Ahr2-morpholino treatment rescued the effect of PCB126 (5 nM) on swim bladder inflation and blocked induction of CYP1A, cox-2a, and cox-2b. With 2 nM PCB126 approximately 30% of eleutheroembryos failed to inflate the swim bladder, but there was no difference in CYP1 or cox-2 mRNA expression between those embryos and embryos showing inflated swim bladder. Our results indicate that PCB126 blocks swim bladder inflation via an Ahr2-mediated mechanism. This mechanism seems independent of CYP1 or cox-2 mRNA induction but may involve abnormal development of swim bladder cells. -- Highlights: ► PCB126 caused cellular changes in the developing swim bladder. ► Swim bladder inflation was not related to expression of CYP1

  6. Deciphering Dimerization Modes of PAS Domains: Computational and Experimental Analyses of the AhR:ARNT Complex Reveal New Insights Into the Mechanisms of AhR Transformation

    PubMed Central

    Corrada, Dario; Soshilov, Anatoly A.; Denison, Michael S.

    2016-01-01

    The Aryl hydrocarbon Receptor (AhR) is a transcription factor that mediates the biochemical response to xenobiotics and the toxic effects of a number of environmental contaminants, including dioxins. Recently, endogenous regulatory roles for the AhR in normal physiology and development have also been reported, thus extending the interest in understanding its molecular mechanisms of activation. Since dimerization with the AhR Nuclear Translocator (ARNT) protein, occurring through the Helix-Loop-Helix (HLH) and PER-ARNT-SIM (PAS) domains, is needed to convert the AhR into its transcriptionally active form, deciphering the AhR:ARNT dimerization mode would provide insights into the mechanisms of AhR transformation. Here we present homology models of the murine AhR:ARNT PAS domain dimer developed using recently available X-ray structures of other bHLH-PAS protein dimers. Due to the different reciprocal orientation and interaction surfaces in the different template dimers, two alternative models were developed for both the PAS-A and PAS-B dimers and they were characterized by combining a number of computational evaluations. Both well-established hot spot prediction methods and new approaches to analyze individual residue and residue-pairwise contributions to the MM-GBSA binding free energies were adopted to predict residues critical for dimer stabilization. On this basis, a mutagenesis strategy for both the murine AhR and ARNT proteins was designed and ligand-dependent DNA binding ability of the AhR:ARNT heterodimer mutants was evaluated. While functional analysis disfavored the HIF2α:ARNT heterodimer-based PAS-B model, most mutants derived from the CLOCK:BMAL1-based AhR:ARNT dimer models of both the PAS-A and the PAS-B dramatically decreased the levels of DNA binding, suggesting this latter model as the most suitable for describing AhR:ARNT dimerization. These novel results open new research directions focused at elucidating basic molecular mechanisms underlying the

  7. Deciphering Dimerization Modes of PAS Domains: Computational and Experimental Analyses of the AhR:ARNT Complex Reveal New Insights Into the Mechanisms of AhR Transformation.

    PubMed

    Corrada, Dario; Soshilov, Anatoly A; Denison, Michael S; Bonati, Laura

    2016-06-01

    The Aryl hydrocarbon Receptor (AhR) is a transcription factor that mediates the biochemical response to xenobiotics and the toxic effects of a number of environmental contaminants, including dioxins. Recently, endogenous regulatory roles for the AhR in normal physiology and development have also been reported, thus extending the interest in understanding its molecular mechanisms of activation. Since dimerization with the AhR Nuclear Translocator (ARNT) protein, occurring through the Helix-Loop-Helix (HLH) and PER-ARNT-SIM (PAS) domains, is needed to convert the AhR into its transcriptionally active form, deciphering the AhR:ARNT dimerization mode would provide insights into the mechanisms of AhR transformation. Here we present homology models of the murine AhR:ARNT PAS domain dimer developed using recently available X-ray structures of other bHLH-PAS protein dimers. Due to the different reciprocal orientation and interaction surfaces in the different template dimers, two alternative models were developed for both the PAS-A and PAS-B dimers and they were characterized by combining a number of computational evaluations. Both well-established hot spot prediction methods and new approaches to analyze individual residue and residue-pairwise contributions to the MM-GBSA binding free energies were adopted to predict residues critical for dimer stabilization. On this basis, a mutagenesis strategy for both the murine AhR and ARNT proteins was designed and ligand-dependent DNA binding ability of the AhR:ARNT heterodimer mutants was evaluated. While functional analysis disfavored the HIF2α:ARNT heterodimer-based PAS-B model, most mutants derived from the CLOCK:BMAL1-based AhR:ARNT dimer models of both the PAS-A and the PAS-B dramatically decreased the levels of DNA binding, suggesting this latter model as the most suitable for describing AhR:ARNT dimerization. These novel results open new research directions focused at elucidating basic molecular mechanisms underlying the

  8. Mixed-ligand copper(II) complexes activate aryl hydrocarbon receptor AhR and induce CYP1A genes expression in human hepatocytes and human cell lines.

    PubMed

    Kubešová, Kateřina; Dořičáková, Aneta; Trávníček, Zdeněk; Dvořák, Zdeněk

    2016-07-25

    The effects of four copper(II) mixed-ligand complexes [Cu(qui1)(L)]NO3·H2O (1-3) and [Cu(qui2)(phen)]NO3 (4), where qui1=2-phenyl-3-hydroxy-4(1H)-quinolinone, Hqui2=2-(4-amino-3,5-dichlorophenyl)-N-propyl-3-hydroxy-4(1H)-quinolinone-7-carboxamide, L=1,10-phenanthroline (phen) (1), 5-methyl-1,10-phenanthroline (mphen) (2), bathophenanthroline (bphen) (3), on transcriptional activities of steroid receptors, nuclear receptors and xenoreceptors have been studied. The complexes (1-4) did not influence basal or ligand-inducible activities of glucocorticoid receptor, androgen receptor, thyroid receptor, pregnane X receptor and vitamin D receptor, as revealed by gene reporter assays. The complexes 1 and 2 dose-dependently induced luciferase activity in stable gene reporter AZ-AhR cell line, and this induction was reverted by resveratrol, indicating involvement of aryl hydrocarbon receptor (AhR) in the process. The complexes 1, 2 and 3 induced CYP1A1 mRNA in LS180 cells and CYP1A1/CYP1A2 in human hepatocytes through AhR. Electrophoretic mobility shift assay EMSA showed that the complexes 1 and 2 transformed AhR in its DNA-binding form. Collectively, we demonstrate that the complexes 1 and 2 activate AhR and induce AhR-dependent genes in human hepatocytes and cancer cell lines. In conclusion, the data presented here might be of toxicological importance, regarding the multiple roles of AhR in human physiology and pathophysiology. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  9. Antagonistic Phenomena in Network Dynamics

    NASA Astrophysics Data System (ADS)

    Motter, Adilson E.; Timme, Marc

    2018-03-01

    Recent research on the network modeling of complex systems has led to a convenient representation of numerous natural, social, and engineered systems that are now recognized as networks of interacting parts. Such systems can exhibit a wealth of phenomena that not only cannot be anticipated from merely examining their parts, as per the textbook definition of complexity, but also challenge intuition even when considered in the context of what is now known in network science. Here, we review the recent literature on two major classes of such phenomena that have far-reaching implications: (a) antagonistic responses to changes of states or parameters and (b) coexistence of seemingly incongruous behaviors or properties - both deriving from the collective and inherently decentralized nature of the dynamics. They include effects as diverse as negative compressibility in engineered materials, rescue interactions in biological networks, negative resistance in fluid networks, and the Braess paradox occurring across transport and supply networks. They also include remote synchronization, chimera states, and the converse of symmetry breaking in brain, power-grid, and oscillator networks as well as remote control in biological and bioinspired systems. By offering a unified view of these various scenarios, we suggest that they are representative of a yet broader class of unprecedented network phenomena that ought to be revealed and explained by future research.

  10. AHR-Enhancing γδ T Cells Develop in Normal Untreated Mice and Fail to Produce IL-4/13, Unlike TH2 Cells and NKT Cells1

    PubMed Central

    Jin, Niyun; Roark, Christina L.; Miyahara, Nobuaki; Taube, Christian; Aydintug, M. Kemal; Wands, JM; Huang, Yafei; Hahn, Youn-Soo; Gelfand, Erwin W.; O’Brien, Rebecca L.; Born, Willi K.

    2008-01-01

    Allergic airway hyperresponsiveness (AHR) in OVA-sensitized and challenged mice, mediated by allergen-specific Th2 cells and Th2-like iNKT cells, develops under the influence of enhancing and inhibitory γδ T cells. The AHR-enhancing cells belong to the Vγ1+ γδ T cell subset, cells that are capable of increasing IL-5 and IL-13 levels in the airways in a manner like Th2 cells. They also synergize with iNKT cells in mediating AHR. However, unlike Th2 cells, the AHR-enhancers arise in untreated mice, and we show here that they exhibit their functional bias already as thymocytes, at an HSAhi maturational stage. In further contrast to Th2 cells and also unlike iNKT cells, they could not be stimulated to produce IL-4 and IL-13, consistent with their synergistic dependence on iNKT cells in mediating AHR. Mice deficient in IFN-γ, TNFRp75 or IL-4 did not produce these AHR-enhancing γδ T cells, but in the absence of IFN-γ, their spontaneous development was restored by adoptive transfer of IFN-γ competent dendritic cells from untreated donors. Intra-peritoneal injection of OVA/alum restored development of the AHR-enhancers in all of the mutant strains, indicating that the enhancers still can be induced when they fail to develop spontaneously, and that they themselves need not express TNFRp75, IFN-γ or IL-4 in order to exert their function. We conclude that both the development and the cytokine potential of the AHR-enhancing γδ T cells differs critically from that of Th2 cells and NKT cells, despite similar influences of these cell populations on AHR. PMID:19201853

  11. The Evolution of Sexually Antagonistic Phenotypes

    PubMed Central

    Perry, Jennifer C.; Rowe, Locke

    2015-01-01

    Sexual conflict occurs whenever there is sexually antagonistic selection on shared traits. When shared traits result from interactions (e.g., mating rate) and have a different genetic basis in each sex (i.e., interlocus conflict), then sex-specific traits that shift the value of these interaction traits toward the sex-specific optimum will be favored. Male traits can be favored that increase the fitness of their male bearers, but decrease the fitness of interacting females. Likewise, female traits that reduce the costs of interacting with harmful males may simultaneously impose costs on males. If the evolution of these antagonistic traits changes the nature of selection acting on the opposite sex, interesting coevolutionary dynamics will result. Here we examine three current issues in the study of sexually antagonistic interactions: the female side of sexual conflict, the ecological context of sexual conflict, and the strength of evidence for sexually antagonistic coevolution. PMID:26032715

  12. Ahr2-dependance of PCB126 effects on the swimbladder in relation to expression of CYP1 and cox-2 genes in developing zebrafish

    PubMed Central

    Jönsson, Maria E.; Kubota, Akira; Timme-Laragy, Alicia; Woodin, Bruce; Stegeman, John J.

    2012-01-01

    The teleost swimbladder is assumed a homolog of the tetrapod lung. Both swimbladder and lung are developmental targets of persistent aryl hydrocarbon receptor (AHR1) agonists; in zebrafish (Danio rerio) the swimbladder fails to inflate with exposure to 3,3’,4,4’,5-pentachlorobiphenyl (PCB126). The mechanism for this effect is unknown, but studies have suggested roles of cytochrome P4501 (CYP1) and cyclooxygenase 2 (Cox-2) in some Ahr-mediated developmental effects in zebrafish. We determined relationships between swimbladder inflation and CYP1 and Cox-2 mRNA expression in PCB126-exposed zebrafish embryos. We also examined effects on β-catenin dependent transcription, histological effects, and Ahr2 dependance of the effect of PCB126 on swimbladder using morpholinos targeting ahr2. One-day-old embryos were exposed to waterborne PCB126 or carrier (DMSO) for 24 h and then held in clean water until day 4, a normal time for swimbladder inflation. The effects of PCB126 were concentration-dependent with EC50 values of 1.4 to 2.0 nM for induction of the CYP1s, 3.7 and 5.1 nM (or higher) for cox-2a and cox-2b induction, and 2.5 nM for inhibition of swimbladder inflation. Histological defects included a compaction of the developing bladder. Ahr2-morpholino treatment rescued the effect of PCB126 (5 nM) on swimbladder inflation and blocked induction of CYP1A, cox-2a, and cox-2b. With 2 nM PCB126 approximately 30% of eleutheroembryos2 failed to inflate the swimbladder, but there was no difference in CYP1 or cox-2 mRNA expression between those embryos and embryos showing inflated swimbladder. Our results indicate that PCB126 blocks swimbladder inflation via an Ahr2-mediated mechanism. This mechanism seems independent of CYP1 or cox-2 mRNA induction but may involve abnormal development of swimbladder cells. PMID:23036320

  13. Ultraviolet B inhibition of DNMT1 activity via AhR activation dependent SIRT1 suppression in CD4+ T cells from systemic lupus erythematosus patients.

    PubMed

    Wu, Zhouwei; Mei, Xingyu; Ying, Zuolin; Sun, Yue; Song, Jun; Shi, Weimin

    2017-06-01

    Previous studies have reported that ultraviolet B (UVB) inhibits DNA methyltransferase1 (DNMT1) activity in CD4+ T cells from systemic lupus erythematosus (SLE) patients. Silent mating type information regulation 2 homolog 1 (SIRT1) is a type of Class III histone deacetylases (HDACs), and has been reported to play roles in the pathogenesis of different autoimmune diseases and can modulate DNMT1 activity. Moreover, aryl hydrocarbon receptor (AhR) has been reported to link UVB with SLE. However, the exact mechanisms by which DNMT1 activity is inhibited by UVB in lupus CD4+ T cells remain largely unknown. To elucidate the exact mechanisms by which DNMT1 activity is inhibited by UVB in lupus CD4+ T cells. Twenty-two newly diagnosed active SLE patients and 30 healthy controls were enrolled in the study. CD4+ T cells were isolated, cultured and treated. DNMT1 activity assay, quantitative real-time PCR (qRT-PCR), Western blotting, RNA interference using small interfering RNA and Chromatin Immunoprecipitation (ChIP) assay were employed. DNMT1 activity was inhibited in si-SIRT1-transfected CD4+ T cells, and increased by the established SIRT1 activator, SRT1720. Moreover, the mRNA and protein expression of SIRT1 were suppressed by UVB exposure in lupus CD4+ T cells. UVB-inhibited DNMT1 activity was reversed by SRT1720 in si-control-transfected lupus CD4+ T cells, but not in si-SIRT1-transfected lupus CD4 + T cells. Furthermore, AhR activation by VAF347 reduced the mRNA and protein expression of SIRT1. ChIP using an antibody against AhR in normal CD4+ T cells revealed a 16-fold stronger signal at the site about 1.6kb upstream from the translation start site of the SIRT1 promoter. Finally, UVB could activate AhR and inhibit the mRNA and protein expression of SIRT1. AhR knockdown abrogated the inhibition of UVB-mediated SIRT1 mRNA and protein expression and DNMT1 activity in lupus CD4+ T cells. UVB suppressed SIRT1 expression via activating AhR, and subsequently inhibited DNMT1

  14. Tumor-Repopulating Cells Induce PD-1 Expression in CD8+ T Cells by Transferring Kynurenine and AhR Activation.

    PubMed

    Liu, Yuying; Liang, Xiaoyu; Dong, Wenqian; Fang, Yi; Lv, Jiadi; Zhang, Tianzhen; Fiskesund, Roland; Xie, Jing; Liu, Jinyan; Yin, Xiaonan; Jin, Xun; Chen, Degao; Tang, Ke; Ma, Jingwei; Zhang, Huafeng; Yu, Jing; Yan, Jun; Liang, Huaping; Mo, Siqi; Cheng, Feiran; Zhou, Yabo; Zhang, Haizeng; Wang, Jing; Li, Jingnan; Chen, Yang; Cui, Bing; Hu, Zhuo-Wei; Cao, Xuetao; Xiao-Feng Qin, F; Huang, Bo

    2018-03-12

    Despite the clinical successes fostered by immune checkpoint inhibitors, mechanisms underlying PD-1 upregulation in tumor-infiltrating T cells remain an enigma. Here, we show that tumor-repopulating cells (TRCs) drive PD-1 upregulation in CD8 + T cells through a transcellular kynurenine (Kyn)-aryl hydrocarbon receptor (AhR) pathway. Interferon-γ produced by CD8 + T cells stimulates release of high levels of Kyn produced by TRCs, which is transferred into adjacent CD8 + T cells via the transporters SLC7A8 and PAT4. Kyn induces and activates AhR and thereby upregulates PD-1 expression. This Kyn-AhR pathway is confirmed in both tumor-bearing mice and cancer patients and its blockade enhances antitumor adoptive T cell therapy efficacy. Thus, we uncovered a mechanism of PD-1 upregulation with potential tumor immunotherapeutic applications. Copyright © 2018 Elsevier Inc. All rights reserved.

  15. Human primordial germ cell formation is diminished by exposure to environmental toxicants acting through the AHR signaling pathway.

    PubMed

    Kee, Kehkooi; Flores, Martha; Cedars, Marcelle I; Reijo Pera, Renee A

    2010-09-01

    Historically, effects of environmental toxicants on human development have been deduced via epidemiological studies because direct experimental analysis has not been possible. However, in recent years, the derivation of human pluripotent stem cells has provided a potential experimental system to directly probe human development. Here, we used human embryonic stem cells (hESCs) to study the effect of environmental toxicants on human germ cell development, with a focus on differentiation of the founding population of primordial germ cells (PGCs), which will go on to form the oocytes of the adult. We demonstrate that human PGC numbers are specifically reduced by exposure to polycyclic aromatic hydrocarbons (PAHs), a group of toxicants common in air pollutants released from gasoline combustion or tobacco smoke. Further, we demonstrate that the adverse effects of PAH exposure are mediated through the aromatic hydrocarbon receptor (AHR) and BAX pathway. This study demonstrates the utility of hESCs as a model system for direct examination of the molecular and genetic pathways of environmental toxicants on human germ cell development.

  16. TCDD and a putative endogenous AhR ligand, ITE, elicit the same immediate changes in gene expression in mouse lung fibroblasts.

    PubMed

    Henry, Ellen C; Welle, Stephen L; Gasiewicz, Thomas A

    2010-03-01

    The aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor, mediates toxicity of several classes of xenobiotics and also has important physiological roles in differentiation, reproduction, and immunity, although the endogenous ligand(s) mediating these functions is/are as yet unidentified. One candidate endogenous ligand, 2-(1'H-indolo-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), is a potent AhR agonist in vitro, activates the murine AhR in vivo, but does not induce toxicity. We hypothesized that ITE and the toxic ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), may modify transcription of different sets of genes to account for their different toxicity. To test this hypothesis, primary mouse lung fibroblasts were exposed to 0.5muM ITE, 0.2nM TCDD, or vehicle for 4 h, and total gene expression was evaluated using microarrays. After this short-term and low-dose treatment, several hundred genes were changed significantly, and the response to ITE and TCDD was remarkably similar, both qualitatively and quantitatively. Induced gene sets included the expected battery of AhR-dependent xenobiotic-metabolizing enzymes, as well as several sets that reflect the inflammatory role of lung fibroblasts. Real time quantitative RT-qPCR assay of several selected genes confirmed these microarray data and further suggested that there may be kinetic differences in expression between ligands. These data suggest that ITE and TCDD elicit an analogous change in AhR conformation such that the initial transcription response is the same. Furthermore, if the difference in toxicity between TCDD and ITE is mediated by differences in gene expression, then it is likely that secondary changes enabled by the persistent TCDD, but not by the shorter lived ITE, are responsible.

  17. TCDD and a Putative Endogenous AhR Ligand, ITE, Elicit the Same Immediate Changes in Gene Expression in Mouse Lung Fibroblasts

    PubMed Central

    Henry, Ellen C.; Welle, Stephen L.; Gasiewicz, Thomas A.

    2010-01-01

    The aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor, mediates toxicity of several classes of xenobiotics and also has important physiological roles in differentiation, reproduction, and immunity, although the endogenous ligand(s) mediating these functions is/are as yet unidentified. One candidate endogenous ligand, 2-(1′H-indolo-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), is a potent AhR agonist in vitro, activates the murine AhR in vivo, but does not induce toxicity. We hypothesized that ITE and the toxic ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), may modify transcription of different sets of genes to account for their different toxicity. To test this hypothesis, primary mouse lung fibroblasts were exposed to 0.5μM ITE, 0.2nM TCDD, or vehicle for 4 h, and total gene expression was evaluated using microarrays. After this short-term and low-dose treatment, several hundred genes were changed significantly, and the response to ITE and TCDD was remarkably similar, both qualitatively and quantitatively. Induced gene sets included the expected battery of AhR-dependent xenobiotic-metabolizing enzymes, as well as several sets that reflect the inflammatory role of lung fibroblasts. Real time quantitative RT-qPCR assay of several selected genes confirmed these microarray data and further suggested that there may be kinetic differences in expression between ligands. These data suggest that ITE and TCDD elicit an analogous change in AhR conformation such that the initial transcription response is the same. Furthermore, if the difference in toxicity between TCDD and ITE is mediated by differences in gene expression, then it is likely that secondary changes enabled by the persistent TCDD, but not by the shorter lived ITE, are responsible. PMID:19933214

  18. Polycyclic Aromatic Hydrocarbons (PAHs) Mediate Transcriptional Activation of the ATP Binding Cassette Transporter ABCB6 Gene via the Aryl Hydrocarbon Receptor (AhR)*

    PubMed Central

    Chavan, Hemantkumar; Krishnamurthy, Partha

    2012-01-01

    Liver is endowed with a mechanism to induce hepatic cytochromes P450 (CYP450s) in response to therapeutic drugs and environmental contaminants, leading to increased detoxification and elimination of the xenobiotics. Each CYP450 is composed of an apoprotein moiety and a heme prosthetic group, which is required for CYP450 activity. Thus, under conditions of CYP450 induction, there is a coordinate increase in heme biosynthesis to compensate for the increased expression of CYP450s. ABCB6, a mitochondrial ATP binding cassette transporter, which regulates coproporphyrinogen transport from the cytoplasm into the mitochondria to complete heme biosynthesis, represents a previously unrecognized rate-limiting step in heme biosynthesis. However, it is not known if exposure to drugs and environmental contaminants induces ABCB6 expression, to assure an adequate and apparently coordinated supply of heme for the generation of functional cytochrome holoprotein. In the present study, we demonstrate that polycyclic aromatic hydrocarbons (PAHs), the widely distributed environmental toxicants shown to induce porphyrin accumulation causing hepatic porphyria, up-regulate ABCB6 expression in both mice and humans. Using siRNA technology and Abcb6 knock-out mice, we demonstrate that PAH-mediated increase in hepatic porphyrins is compromised in the absence of ABCB6. Moreover, in vivo studies in aryl hydrocarbon receptor (AhR) knock-out mice demonstrate that PAH induction of ABCB6 is mediated by AhR. Promoter activation studies combined with electrophoretic mobility shift assay and chromatin immunoprecipitation assay demonstrate direct interactions between the AhR binding sites in the ABCB6 promoter and the AhR receptor, implicating drug activation mechanisms for ABCB6 similar to those found in inducible cytochrome P450s. These studies are the first to describe direct transcriptional activation of both mouse and human ABCB6 by xenobiotics. PMID:22761424

  19. The tertiary structures of porcine AhR and ARNT proteins and molecular interactions within the TCDD/AhR/ARNT complex.

    PubMed

    Orlowska, Karina; Molcan, Tomasz; Swigonska, Sylwia; Sadowska, Agnieszka; Jablonska, Monika; Nynca, Anna; Jastrzebski, Jan P; Ciereszko, Renata E

    2016-06-01

    The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that can be activated by structurally diverse synthetic and natural chemicals, including toxic environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In the present study, homology models of the porcine AhR-ligand binding domain (LBD) and the porcine aryl hydrocarbon receptor nuclear translocator-ligand binding domain (ARNT-LBD) were created on the basis of structures of closely related respective proteins i.e., human Hif-2α and ARNT. Molecular docking of TCDD to the porcine AhR-LBD model revealed high binding affinity (-8.8kcal/mol) between TCDD and the receptor. Moreover, formation of the TCDD/AhR-LBD complex was confirmed experimentally with the use of electrophoretic mobility shift assay (EMSA). It was found that TCDD (10nM, 2h of incubation) not only bound to the AhR in the porcine granulosa cells but also activated the receptor. The current study provides a framework for examining the key events involved in the ligand-dependent activation of the AhR. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Phytomonitoring and phytoremediation of agrochemicals and related compounds based on recombinant cytochrome P450s and aryl hydrocarbon receptors (AhRs).

    PubMed

    Shimazu, Sayuri; Inui, Hideyuki; Ohkawa, Hideo

    2011-04-13

    Molecular mechanisms of metabolism and modes of actions of agrochemicals and related compounds are important for understanding selective toxicity, biodegradability, and monitoring of biological effects on nontarget organisms. It is well-known that in mammals, cytochrome P450 (P450 or CYP) monooxygenases metabolize lipophilic foreign compounds. These P450 species are inducible, and both CYP1A1 and CYP1A2 are induced by aryl hydrocarbon receptor (AhR) combined with a ligand. Gene engineering of P450 and NADPH cytochrome P450 oxidoreductase (P450 reductase) was established for bioconversion. Also, gene modification of AhRs was developed for recombinant AhR-mediated β-glucronidase (GUS) reporter assay of AhR ligands. Recombinant P450 genes were transformed into plants for phytoremediation, and recombinant AhR-mediated GUS reporter gene expression systems were each transformed into plants for phytomonitoring. Transgenic rice plants carrying CYP2B6 metabolized the herbicide metolachlor and remarkably reduced the residues in the plants and soils under paddy field conditions. Transgenic Arabidopsis plants carrying recombinant guinea pig (g) AhR-mediated GUS reporter genes detected PCB126 at the level of 10 ng/g soils in the presence of biosurfactants MEL-B. Both phytomonitoring and phytoremediation plants were each evaluated from the standpoint of practical uses.

  1. NMDA receptor antagonists inhibit catalepsy induced by either dopamine D1 or D2 receptor antagonists.

    PubMed

    Moore, N A; Blackman, A; Awere, S; Leander, J D

    1993-06-11

    In the present study, we investigated the ability of NMDA receptor antagonists to inhibit catalepsy induced by haloperidol, or SCH23390 and clebopride, selective dopamine D1 and D2 receptor antagonists respectively. Catalepsy was measured by recording the time the animal remained with its forepaws placed over a rod 6 cm above the bench. Pretreatment with either the non-competitive NMDA receptor antagonist, MK-801 (0.25-0.5 mg/kg i.p.) or the competitive antagonist, LY274614 (10-20 mg/kg i.p.) reduced the cataleptic response produced by haloperidol (10 mg/kg), SCH23390 (2.5-10 mg/kp i.p.) or clebopride (5-20 mg/kg i.p.). This demonstrates that NMDA receptor antagonists will reduce both dopamine D1 and D2 receptor antagonist-induced catalepsy. Muscle relaxant doses of chlordiazepoxide (10 mg/kg i.p.) failed to reduce the catalepsy induced by haloperidol, suggesting that the anticataleptic effect of the NMDA receptor antagonists was not due to a non-specific action. These results support the hypothesis that NMDA receptor antagonists may have beneficial effects in disorders involving reduced dopaminergic function, such as Parkinson's disease.

  2. Studies on the Role of The Ah Receptor (AhR) on the Etiology of Breast Cancer: A Novel Idea of Identifying this Receptor as a New Therapeutic Target

    DTIC Science & Technology

    2010-09-01

    found that the most potent phytochemical suppressors of cell proliferation of P20E cells were curcumin (10 µM approximately 80 to 90% suppression...effectiveness of a number of phytochemicals from edible plants known to block AhR in attenuating the expression of high rates of cell proliferation...selected number of those phytochemicals , by xenografting those AhR overexpressing human breast cancer cells into athymic nude mice, and by treating

  3. Tachykinin antagonists have potent local anaesthetic actions.

    PubMed

    Post, C; Butterworth, J F; Strichartz, G R; Karlsson, J A; Persson, C G

    1985-11-19

    Contrary to what would have been expected, an antagonist of substance P (SP) [Arg5,D-Trp7,9]SP-(5-11) inhibited the neurogenic contraction of isolated guinea-pig hilus bronchi more readily than a contraction produced by exogenous SP. Furthermore, it has previously been shown that a tachykinin antagonist given intrathecally produced motor blockade as do local anaesthetic drugs. We therefore examined whether tachykinin antagonists had a depressant action on axonal neurotransmission. The compound action potential (APc) of the frog isolated sciatic nerve was suppressed in a concentration-dependent manner by the tachykinin antagonists [D-Pro2,D-Trp7,9]SP and [Arg5,D-Trp7,9]Sp-(5-11), both being about 4 times more potent than lidocaine. SP itself was without effect. Similarly in the rat isolated sciatic nerve [D-Pro2,D-Trp7,9]SP suppressed the APc. It was more potent in the A alpha- than in the C-fibres. SP did not affect conduction in either fibre type. In conscious guinea-pigs [D-Pro2,D-Trp7,9]SP injected adjacent to the sciatic nerve was found to block motor but not sensory functions of the limb. Thus, commonly used tachykinin antagonists, but not SP itself, have potent local anaesthetic properties. This should be considered when these agents are employed as pharmacological tools.

  4. Role of zebrafish cytochrome P450 CYP1C genes in the reduced mesencephalic vein blood flow caused by activation of AHR2

    SciTech Connect

    Kubota, Akira, E-mail: akubota@whoi.edu; Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543; Stegeman, John J.

    2011-06-15

    2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) causes various signs of toxicity in early life stages of vertebrates through activation of the aryl hydrocarbon receptor (AHR). We previously reported a sensitive and useful endpoint of TCDD developmental toxicity in zebrafish, namely a decrease in blood flow in the dorsal midbrain, but downstream genes involved in the effect are not known. The present study addressed the role of zebrafish cytochrome P450 1C (CYP1C) genes in association with a decrease in mesencephalic vein (MsV) blood flow. The CYP1C subfamily was recently discovered in fish and includes the paralogues CYP1C1 and CYP1C2, both of which are induced viamore » AHR2 in zebrafish embryos. We used morpholino antisense oligonucleotides (MO or morpholino) to block initiation of translation of the target genes. TCDD-induced mRNA expression of CYP1Cs and a decrease in MsV blood flow were both blocked by gene knockdown of AHR2. Gene knockdown of CYP1C1 by two different morpholinos and CYP1C2 by two different morpholinos, but not by their 5 nucleotide-mismatch controls, was effective in blocking reduced MsV blood flow caused by TCDD. The same CYP1C-MOs prevented reduction of blood flow in the MsV caused by {beta}-naphthoflavone (BNF), representing another class of AHR agonists. Whole-mount in situ hybridization revealed that mRNA expression of CYP1C1 and CYP1C2 was induced by TCDD most strongly in branchiogenic primordia and pectoral fin buds. In situ hybridization using head transverse sections showed that TCDD increased the expression of both CYP1Cs in endothelial cells of blood vessels, including the MsV. These results indicate a potential role of CYP1C1 and CYP1C2 in the local circulation failure induced by AHR2 activation in the dorsal midbrain of the zebrafish embryo. - Research Highlights: > We examine the roles of zebrafish CYP1C1 and CYP1C2 in TCDD developmental toxicity. > TCDD induces mRNA expression of both CYP1Cs in the mesencephalic vein. > Knockdown

  5. Detecting sexually antagonistic coevolution with population crosses.

    PubMed

    Rowe, Locke; Cameron, Erin; Day, Troy

    2003-10-07

    The result of population crosses on traits such as mating rate, oviposition rate and survivorship are increasingly used to distinguish between modes of coevolution between the sexes. Two key hypotheses, erected from a verbal theory of sexually antagonistic coevolution, have been the subject of several recent tests. First, statistical interactions arising in population crosses are suggested to be indicative of a complex signal/receiver system. In the case of oviposition rates, an interaction between populations (x, y and z) would be indicated by the rank order of female oviposition rates achieved by x, y and z males changing depending upon the female (x, y or z) with which they mated. Second, under sexually antagonistic coevolution females will do 'best' when mated with their own males, where best is defined by the weakest response to the signal and the highest fitness. We test these hypotheses by crossing strains generated from a formal model of sexually antagonistic coevolution. Strains differ in the strength of natural selection acting on male and female traits. In our model, we assume sexually antagonistic coevolution of a single male signal and female receptor. The female receptor is treated as a preference function where both the slope and intercept of the function can evolve. Our results suggest that neither prediction is consistently supported. Interactions are not diagnostic of complex signal-receiver systems, and even under sexually antagonistic coevolution, females may do better mating with males of strains other than their own. These results suggest a reinterpretation of several recent experiments and have important implications for developing theories of speciation when sexually antagonistic coevolution is involved.

  6. Intravenous Narcotic Antagonists in Ambulatory Oral Surgery

    PubMed Central

    Greenfield, William; Granada, Margarito G.

    1975-01-01

    Results of a study indicate that significant respiratory depression can be produced by the intravenous administration of narcotics in the anesthetic management of oral surgery patients. Naloxone hydrochloride reversed this reaction in all instances. Naloxone is a unique narcotic antagonist in that it does not possess agonistic properties of its own, it is effective in reversing respiratory depression resulting from all commonly used narcotics and narcotic antagonists, it causes no undesirable side effects, and it acts as a placebo when administered to a patient who has not had a narcotic. The use of naloxone should be considered when a potent narcotic is administered to an ambulatory patient. PMID:19598479

  7. Sickle cell crisis and endothelin antagonists.

    PubMed

    Angerio, Allan D; Lee, Nicole D

    2003-01-01

    Sickle cell crisis may be more complex than a vaso-occlusive event in response to hypoxia. Endothelin-1 (ET-1) is a potent vasoconstrictor and mitogen secreted in response to hypoxia. ET-1 contributes to the vaso-occlusion and inflammation in sickle cell crisis. ET-1 antagonists may be useful in the prevention and treatment of crisis.

  8. Antagonistic and synergistic interactions among predators.

    PubMed

    Huxel, Gary R

    2007-08-01

    The structure and dynamics of food webs are largely dependent upon interactions among consumers and their resources. However, interspecific interactions such as intraguild predation and interference competition can also play a significant role in the stability of communities. The role of antagonistic/synergistic interactions among predators has been largely ignored in food web theory. These mechanisms influence predation rates, which is one of the key factors regulating food web structure and dynamics, thus ignoring them can potentially limit understanding of food webs. Using nonlinear models, it is shown that critical aspects of multiple predator food web dynamics are antagonistic/synergistic interactions among predators. The influence of antagonistic/synergistic interactions on coexistence of predators depended largely upon the parameter set used and the degree of feeding niche differentiation. In all cases when there was no effect of antagonism or synergism (a ( ij )=1.00), the predators coexisted. Using the stable parameter set, coexistence occurred across the range of antagonism/synergism used. However, using the chaotic parameter strong antagonism resulted in the extinction of one or both species, while strong synergism tended to coexistence. Whereas using the limit cycle parameter set, coexistence was strongly dependent on the degree of feeding niche overlap. Additionally increasing the degree of feeding specialization of the predators on the two prey species increased the amount of parameter space in which coexistence of the two predators occurred. Bifurcation analyses supported the general pattern of increased stability when the predator interaction was synergistic and decreased stability when it was antagonistic. Thus, synergistic interactions should be more common than antagonistic interactions in ecological systems.

  9. Assessment of energetic costs of AhR activation by β-naphthoflavone in rainbow trout (Oncorhynchus mykiss) hepatocytes using metabolic flux analysis

    SciTech Connect

    Nault, Rance, E-mail: naultran@msu.edu; Abdul-Fattah, Hiba; Mironov, Gleb G.

    2013-08-15

    Exposure to environmental contaminants such as activators of the aryl hydrocarbon receptor (AhR) leads to the induction of defense and detoxification mechanisms. While these mechanisms allow organisms to metabolize and excrete at least some of these environmental contaminants, it has been proposed that these mechanisms lead to significant energetic challenges. This study tests the hypothesis that activation of the AhR by the model agonist β-naphthoflavone (βNF) results in increased energetic costs in rainbow trout (Oncorhynchus mykiss) hepatocytes. To address this hypothesis, we employed traditional biochemical approaches to examine energy allocation and metabolism including the adenylate energy charge (AEC), protein synthesismore » rates, Na{sup +}/K{sup +}-ATPase activity, and enzyme activities. Moreover, we have used for the first time in a fish cell preparation, metabolic flux analysis (MFA) an in silico approach for the estimation of intracellular metabolic fluxes. Exposure of trout hepatocytes to 1 μM βNF for 48 h did not alter hepatocyte AEC, protein synthesis, or Na{sup +}/K{sup +}-ATPase activity but did lead to sparing of glycogen reserves and changes in activities of alanine aminotransferase and citrate synthase suggesting altered metabolism. Conversely, MFA did not identify altered metabolic fluxes, although we do show that the dynamic metabolism of isolated trout hepatocytes poses a significant challenge for this type of approach which should be considered in future studies. - Highlights: • Energetic costs of AhR activation by βNF was examined in rainbow trout hepatocytes. • Metabolic flux analysis was performed on a fish cell preparation for the first time. • Exposure to βNF led to sparing of glycogen reserves and altered enzyme activities. • Adenylate energy charge was maintained despite temporal changes in metabolism.« less

  10. A rapid and reagent-free bioassay for the detection of dioxin-like compounds and other aryl hydrocarbon receptor (AhR) agonists using autobioluminescent yeast.

    PubMed

    Xu, Tingting; Young, Anna; Marr, Enolia; Sayler, Gary; Ripp, Steven; Close, Dan

    2018-02-01

    An autonomously bioluminescent Saccharomyces cerevisiae BLYAhS bioreporter was developed in this study for the simple and rapid detection of dioxin-like compounds (DLCs) and aryl hydrocarbon receptor (AhR) agonists. This recombinant yeast reporter was based on a synthetic bacterial luciferase reporter gene cassette (lux) that can produce the luciferase as well as the enzymes capable of self-synthesizing the requisite substrates for bioluminescent production from endogenous cellular metabolites. As a result, bioluminescent signal production is generated continuously and autonomously without cell lysis or exogenous reagent addition. By linking the expression of the autobioluminescent lux reporter cassette to AhR activation via the use of a dioxin-responsive promoter, the S. cerevisiae BLYAhS bioreporter emitted a bioluminescent signal in response to DLC exposure in a dose-responsive manner. The model dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), could be detected within 4 h with a half maximal effective concentration (EC 50 ) of ~ 8.1 nM and a lower detection limit of 500 pM. The autobioluminescent response of BLYAhS to other AhR agonists, including 2,3,7,8-tetrachlorodibenzofuran (TCDF), polychlorinated bisphenyl congener 126 (PCB-126) and 169 (PCB-169), 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin (HxCDD), 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD), benzo[a]pyrene (BaP), and β-naphthoflavone (bNF), were also characterized in this study. The non-destructive and reagent-free nature of the BLYAhS reporter assay facilitated near-continuous, automated signal acquisition without additional hands-on effort and cost, providing a simple and cost-effective method for rapid DLC detection.

  11. Transcriptomic assessment of resistance to effects of an aryl hydrocarbon receptor (AHR) agonist in embryos of Atlantic killifish (Fundulus heteroclitus) from a marine Superfund site

    PubMed Central

    2011-01-01

    Background Populations of Atlantic killifish (Fundulus heteroclitus) have evolved resistance to the embryotoxic effects of polychlorinated biphenyls (PCBs) and other halogenated and nonhalogenated aromatic hydrocarbons that act through an aryl hydrocarbon receptor (AHR)-dependent signaling pathway. The resistance is accompanied by reduced sensitivity to induction of cytochrome P450 1A (CYP1A), a widely used biomarker of aromatic hydrocarbon exposure and effect, but whether the reduced sensitivity is specific to CYP1A or reflects a genome-wide reduction in responsiveness to all AHR-mediated changes in gene expression is unknown. We compared gene expression profiles and the response to 3,3',4,4',5-pentachlorobiphenyl (PCB-126) exposure in embryos (5 and 10 dpf) and larvae (15 dpf) from F. heteroclitus populations inhabiting the New Bedford Harbor, Massachusetts (NBH) Superfund site (PCB-resistant) and a reference site, Scorton Creek, Massachusetts (SC; PCB-sensitive). Results Analysis using a 7,000-gene cDNA array revealed striking differences in responsiveness to PCB-126 between the populations; the differences occur at all three stages examined. There was a sizeable set of PCB-responsive genes in the sensitive SC population, a much smaller set of PCB-responsive genes in NBH fish, and few similarities in PCB-responsive genes between the two populations. Most of the array results were confirmed, and additional PCB-regulated genes identified, by RNA-Seq (deep pyrosequencing). Conclusions The results suggest that NBH fish possess a gene regulatory defect that is not specific to one target gene such as CYP1A but rather lies in a regulatory pathway that controls the transcriptional response of multiple genes to PCB exposure. The results are consistent with genome-wide disruption of AHR-dependent signaling in NBH fish. PMID:21609454

  12. Transcriptomic assessment of resistance to effects of an aryl hydrocarbon receptor (AHR) agonist in embryos of Atlantic killifish (Fundulus heteroclitus) from a marine Superfund site.

    PubMed

    Oleksiak, Marjorie F; Karchner, Sibel I; Jenny, Matthew J; Franks, Diana G; Welch, David B Mark; Hahn, Mark E

    2011-05-24

    Populations of Atlantic killifish (Fundulus heteroclitus) have evolved resistance to the embryotoxic effects of polychlorinated biphenyls (PCBs) and other halogenated and nonhalogenated aromatic hydrocarbons that act through an aryl hydrocarbon receptor (AHR)-dependent signaling pathway. The resistance is accompanied by reduced sensitivity to induction of cytochrome P450 1A (CYP1A), a widely used biomarker of aromatic hydrocarbon exposure and effect, but whether the reduced sensitivity is specific to CYP1A or reflects a genome-wide reduction in responsiveness to all AHR-mediated changes in gene expression is unknown. We compared gene expression profiles and the response to 3,3',4,4',5-pentachlorobiphenyl (PCB-126) exposure in embryos (5 and 10 dpf) and larvae (15 dpf) from F. heteroclitus populations inhabiting the New Bedford Harbor, Massachusetts (NBH) Superfund site (PCB-resistant) and a reference site, Scorton Creek, Massachusetts (SC; PCB-sensitive). Analysis using a 7,000-gene cDNA array revealed striking differences in responsiveness to PCB-126 between the populations; the differences occur at all three stages examined. There was a sizeable set of PCB-responsive genes in the sensitive SC population, a much smaller set of PCB-responsive genes in NBH fish, and few similarities in PCB-responsive genes between the two populations. Most of the array results were confirmed, and additional PCB-regulated genes identified, by RNA-Seq (deep pyrosequencing). The results suggest that NBH fish possess a gene regulatory defect that is not specific to one target gene such as CYP1A but rather lies in a regulatory pathway that controls the transcriptional response of multiple genes to PCB exposure. The results are consistent with genome-wide disruption of AHR-dependent signaling in NBH fish.

  13. New CYP1 genes in the frog Xenopus (Silurana) tropicalis: Induction patterns and effects of AHR agonists during development

    SciTech Connect

    Joensson, Maria E., E-mail: maria.jonsson@ebc.uu.se; Biology Department, Redfield 3-42 MS 32, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543; Berg, Cecilia

    2011-01-15

    The Xenopus tropicalis genome shows a single gene in each of the four cytochrome P450 1 (CYP1) subfamilies that occur in vertebrates, designated as CYP1A, CYP1B1, CYP1C1, and CYP1D1. We cloned the cDNAs of these genes and examined their expression in untreated tadpoles and in tadpoles exposed to waterborne aryl hydrocarbon receptor agonists, 3,3',4,4',5-pentachlorobiphenyl (PCB126), {beta}-naphthoflavone ({beta}NF), or indigo. We also examined the effects of PCB126 on expression of genes involved in stress response, cell proliferation, thyroid homeostasis, and prostaglandin synthesis. PCB126 induced CYP1A, CYP1B1, and CYP1C1 but had little effect on CYP1D1 (77-, 1.7-, 4.6- and 1.4-fold induction versusmore » the control, respectively). {beta}NF induced CYP1A and CYP1C1 (26- and 2.5-fold), while, under conditions used, indigo tended to induce only CYP1A (1.9-fold). The extent of CYP1 induction by PCB126 and {beta}NF was positively correlated to the number of putative dioxin response elements 0-20 kb upstream of the start codons. No morphological effect was observed in tadpoles exposed to 1 nM-10 {mu}M PCB126 at two days post-fertilization (dpf) and screened 20 days later. However, in 14-dpf tadpoles a slight up-regulation of the genes for PCNA, transthyretin, HSC70, Cu-Zn SOD, and Cox-2 was observed two days after exposure to 1 {mu}M PCB126. This study of the full suite of CYP1 genes in an amphibian species reveals gene- and AHR agonist-specific differences in response, as well as a much lower sensitivity to CYP1 induction and short-term toxicity by PCB126 compared with in fish larvae. The single genes in each CYP1 subfamily may make X. tropicalis a useful model for mechanistic studies of CYP1 functions.« less

  14. ITE and TCDD differentially regulate the vascular remodeling of rat placenta via the activation of AhR.

    PubMed

    Wu, Yanming; Chen, Xiao; Zhou, Qian; He, Qizhi; Kang, Jiuhong; Zheng, Jing; Wang, Kai; Duan, Tao

    2014-01-01

    Vascular remodeling in the placenta is essential for normal fetal development. The previous studies have demonstrated that in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, an environmental toxicant) induces the intrauterine fetal death in many species via the activation of aryl hydrocarbon receptor (AhR). In the current study, we compared the effects of 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) and TCDD on the vascular remodeling of rat placentas. Pregnant rats on gestational day (GD) 15 were randomly assigned into 5 groups, and were exposed to a single dose of 1.6 and 8.0 mg/kg body weight (bw) ITE, 1.6 and 8.0 µg/kg bw TCDD, or an equivalent volume of the vehicle, respectively. The dams were sacrificed on GD20 and the placental tissues were gathered. The intrauterine fetal death was observed only in 8.0 µg/kg bw TCDD-exposed group and no significant difference was seen in either the placental weight or the fetal weight among all these groups. The immunohistochemical and histological analyses revealed that as compared with the vehicle-control, TCDD, but not ITE, suppressed the placental vascular remodeling, including reduced the ratio of the placental labyrinth zone to the basal zone thickness (at least 0.71 fold of control), inhibited the maternal sinusoids dilation and thickened the trophoblastic septa. However, no marked difference was observed in the density of fetal capillaries in the labyrinth zone among these groups, although significant differences were detected in the expression of angiogenic growth factors between ITE and TCDD-exposed groups, especially Angiopoietin-2 (Ang-2), Endoglin, Interferon-γ (IFN-γ) and placenta growth factor (PIGF). These results suggest ITE and TCDD differentially regulate the vascular remodeling of rat placentas, as well as the expression of angiogenic factors and their receptors, which in turn may alter the blood flow in the late gestation and partially resulted in

  15. ITE and TCDD Differentially Regulate the Vascular Remodeling of Rat Placenta via the Activation of AhR

    PubMed Central

    Zhou, Qian; He, Qizhi; Kang, Jiuhong; Zheng, Jing; Wang, Kai; Duan, Tao

    2014-01-01

    Vascular remodeling in the placenta is essential for normal fetal development. The previous studies have demonstrated that in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, an environmental toxicant) induces the intrauterine fetal death in many species via the activation of aryl hydrocarbon receptor (AhR). In the current study, we compared the effects of 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) and TCDD on the vascular remodeling of rat placentas. Pregnant rats on gestational day (GD) 15 were randomly assigned into 5 groups, and were exposed to a single dose of 1.6 and 8.0 mg/kg body weight (bw) ITE, 1.6 and 8.0 µg/kg bw TCDD, or an equivalent volume of the vehicle, respectively. The dams were sacrificed on GD20 and the placental tissues were gathered. The intrauterine fetal death was observed only in 8.0 µg/kg bw TCDD-exposed group and no significant difference was seen in either the placental weight or the fetal weight among all these groups. The immunohistochemical and histological analyses revealed that as compared with the vehicle-control, TCDD, but not ITE, suppressed the placental vascular remodeling, including reduced the ratio of the placental labyrinth zone to the basal zone thickness (at least 0.71 fold of control), inhibited the maternal sinusoids dilation and thickened the trophoblastic septa. However, no marked difference was observed in the density of fetal capillaries in the labyrinth zone among these groups, although significant differences were detected in the expression of angiogenic growth factors between ITE and TCDD-exposed groups, especially Angiopoietin-2 (Ang-2), Endoglin, Interferon-γ (IFN-γ) and placenta growth factor (PIGF). These results suggest ITE and TCDD differentially regulate the vascular remodeling of rat placentas, as well as the expression of angiogenic factors and their receptors, which in turn may alter the blood flow in the late gestation and partially resulted in

  16. Effect of a Hypocretin/Orexin Antagonist on Neurocognitive Performance

    DTIC Science & Technology

    2010-09-30

    a novel hypocretiniorexin antagonist, almorexant (ALM), to a standard hypnotic , zolpidem (ZOL), and placebo (PBO) on neurocognitive performance at...Placebo-Controlled, Randomized, Parallel- Group Study Comparing the Effect of a Novel HypocretiniOrexin Antagonist (Almorexant) Versus a Standard Hypnotic ...Group Study Comparing the Effect of a Novel HypocretiniOrexin Antagonist (Almorexant) Versus a Standard Hypnotic (Zolpidem) and Placebo on

  17. Aryl hydrocarbon receptor (AHR): "pioneer member" of the basic-helix/loop/helix per-Arnt-sim (bHLH/PAS) family of "sensors" of foreign and endogenous signals.

    PubMed

    Nebert, Daniel W

    2017-07-01

    The basic-helix/loop/helix per-Arnt-sim (bHLH/PAS) family comprises many transcription factors, found throughout all three kingdoms of life; bHLH/PAS members "sense" innumerable intracellular and extracellular "signals" - including endogenous compounds, foreign chemicals, gas molecules, redox potential, photons (light), gravity, heat, and osmotic pressure. These signals then initiate downstream signaling pathways involved in responding to that signal. The term "PAS", abbreviation for "per-Arnt-sim" was first coined in 1991. Although the mouse Arnt gene was not identified until 1991, evidence of its co-transcriptional binding partner, aryl hydrocarbon receptor (AHR), was first reported in 1974 as a "sensor" of foreign chemicals, up-regulating cytochrome P450 family 1 (CYP1) and other enzyme activities that usually metabolize the signaling chemical. Within a few years, AHR was proposed also to participate in inflammation. The mouse [Ah] locus was shown (1973-1989) to be relevant to chemical carcinogenesis, mutagenesis, toxicity and teratogenesis, the mouse Ahr gene was cloned in 1992, and the first Ahr(-/-) knockout mouse line was reported in 1995. After thousands of studies from the early 1970s to present day, we now realize that AHR participates in dozens of signaling pathways involved in critical-life processes, affecting virtually every organ and cell-type in the animal, including many invertebrates. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Protective effects of levamisole, acetylsalicylic acid, and α-tocopherol against dioxin toxicity measured as the expression of AhR and COX-2 in a chicken embryo model.

    PubMed

    Gostomska-Pampuch, Kinga; Ostrowska, Alicja; Kuropka, Piotr; Dobrzyński, Maciej; Ziółkowski, Piotr; Kowalczyk, Artur; Łukaszewicz, Ewa; Gamian, Andrzej; Całkosiński, Ireneusz

    2017-04-01

    Polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxins) are classed as persistent organic pollutants and have adverse effects on multiple functions within the body. Dioxins are known carcinogens, immunotoxins, and teratogens. Dioxins are transformed in vivo, and interactions between the products and the aryl hydrocarbon receptor (AhR) lead to the formation of proinflammatory and toxic metabolites. The aim of this study was to determine whether α-tocopherol (vitamin E), acetylsalicylic acid (ASA), and levamisole can decrease the amount of damage caused by dioxins. Fertile Hubbard Flex commercial line chicken eggs were injected with solutions containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or containing TCDD and the test compounds. The chicken embryos and organs were analyzed after 7 and 13 days. The levels at which AhR and cyclooxygenase-2 (COX-2) proteins (which are induced during inflammation) were expressed were evaluated by performing immunohistochemical analyses on embryos treated with TCDD alone or with TCDD and the test compounds. TCDD caused developmental disorders and increased AhR and COX-2 expression in the chicken embryo tissues. Vitamin E, levamisole, ASA, and ASA plus vitamin E inhibited AhR and COX-2 expression in embryos after 7 days and decreased AhR and COX-2 expression in embryos after 13 days. ASA, levamisole, and ASA plus vitamin E weakened the immune response and prevented multiple organ changes. Vitamin E was not fully protective against developmental changes in the embryos.

  19. Use of aldosterone antagonists in resistant hypertension.

    PubMed

    Calhoun, David A

    2006-01-01

    Resistant hypertension is defined as an elevated blood pressure in spite of treatment with 3 different antihypertensive agents. The prevalence of resistant hypertension is unknown, but recent cross-sectional analyses and hypertension outcome studies suggest it is a common clinical problem and will become even more so with an aging and increasingly heavy population. Secondary causes of hypertension are common in patients with resistant hypertension, in particular, obstructive sleep apnea and hyperaldosteronism. Treatment of resistant hypertension is predicated upon identification and reversal of secondary causes of hypertension, as possible, and effective use of multidrug regimens. Recent clinical studies indicate that aldosterone antagonists, spironolactone and amiloride, provide significant additional blood pressure reduction when added to treatment regimens of patients with resistant hypertension. Both agents are generally well tolerated. Hyperkalemia is an uncommon complication of aldosterone antagonists, but it can occur; therefore, biochemical monitoring is necessary, particularly in high-risk patients.

  20. Interactions of Freshwater Cyanobacteria with Bacterial Antagonists.

    PubMed

    Osman, Omneya Ahmed; Beier, Sara; Grabherr, Manfred; Bertilsson, Stefan

    2017-04-01

    Cyanobacterial and algal mass development, or blooms, have severe effects on freshwater and marine systems around the world. Many of these phototrophs produce a variety of potent toxins, contribute to oxygen depletion, and affect water quality in several ways. Coexisting antagonists, such as cyanolytic bacteria, hold the potential to suppress, or even terminate, such blooms, yet the nature of this interaction is not well studied. We isolated 31 cyanolytic bacteria affiliated with the genera Pseudomonas , Stenotrophomonas , Acinetobacter , and Delftia from three eutrophic freshwater lakes in Sweden and selected four phylogenetically diverse bacterial strains with strong-to-moderate lytic activity. To characterize their functional responses to the presence of cyanobacteria, we performed RNA sequencing (RNA-Seq) experiments on coculture incubations, with an initial predator-prey ratio of 1:1. Genes involved in central cellular pathways, stress-related heat or cold shock proteins, and antitoxin genes were highly expressed in both heterotrophs and cyanobacteria. Heterotrophs in coculture expressed genes involved in cell motility, signal transduction, and putative lytic activity. l,d-Transpeptidase was the only significantly upregulated lytic gene in Stenotrophomonas rhizophila EK20. Heterotrophs also shifted their central metabolism from the tricarboxylic acid cycle to the glyoxylate shunt. Concurrently, cyanobacteria clearly show contrasting antagonistic interactions with the four tested heterotrophic strains, which is also reflected in the physical attachment to their cells. In conclusion, antagonistic interactions with cyanobacteria were initiated within 24 h, and expression profiles suggest varied responses for the different cyanobacteria and studied cyanolytes. IMPORTANCE Here, we present how gene expression profiles can be used to reveal interactions between bloom-forming freshwater cyanobacteria and antagonistic heterotrophic bacteria. Species-specific responses

  1. Interactions of Freshwater Cyanobacteria with Bacterial Antagonists

    PubMed Central

    Beier, Sara; Grabherr, Manfred

    2017-01-01

    ABSTRACT Cyanobacterial and algal mass development, or blooms, have severe effects on freshwater and marine systems around the world. Many of these phototrophs produce a variety of potent toxins, contribute to oxygen depletion, and affect water quality in several ways. Coexisting antagonists, such as cyanolytic bacteria, hold the potential to suppress, or even terminate, such blooms, yet the nature of this interaction is not well studied. We isolated 31 cyanolytic bacteria affiliated with the genera Pseudomonas, Stenotrophomonas, Acinetobacter, and Delftia from three eutrophic freshwater lakes in Sweden and selected four phylogenetically diverse bacterial strains with strong-to-moderate lytic activity. To characterize their functional responses to the presence of cyanobacteria, we performed RNA sequencing (RNA-Seq) experiments on coculture incubations, with an initial predator-prey ratio of 1:1. Genes involved in central cellular pathways, stress-related heat or cold shock proteins, and antitoxin genes were highly expressed in both heterotrophs and cyanobacteria. Heterotrophs in coculture expressed genes involved in cell motility, signal transduction, and putative lytic activity. l,d-Transpeptidase was the only significantly upregulated lytic gene in Stenotrophomonas rhizophila EK20. Heterotrophs also shifted their central metabolism from the tricarboxylic acid cycle to the glyoxylate shunt. Concurrently, cyanobacteria clearly show contrasting antagonistic interactions with the four tested heterotrophic strains, which is also reflected in the physical attachment to their cells. In conclusion, antagonistic interactions with cyanobacteria were initiated within 24 h, and expression profiles suggest varied responses for the different cyanobacteria and studied cyanolytes. IMPORTANCE Here, we present how gene expression profiles can be used to reveal interactions between bloom-forming freshwater cyanobacteria and antagonistic heterotrophic bacteria. Species

  2. Nonsteroidal antagonists of the mineralocorticoid receptor.

    PubMed

    Kolkhof, Peter; Nowack, Christina; Eitner, Frank

    2015-09-01

    The broad clinical use of steroidal mineralocorticoid receptor antagonists (MRAs) is limited by the potential risk of inducing hyperkalemia when given on top of renin-angiotensin system blockade. Drug discovery campaigns have been launched aiming for the identification of nonsteroidal MRAs with an improved safety profile. This review analyses the evidence for the potential of improved safety profiles of nonsteroidal MRAs and the current landscape of clinical trials with nonsteroidal MRAs. At least three novel nonsteroidal MRAs have reportedly demonstrated an improved therapeutic index (i.e. less risk for hyperkalemia) in comparison to steroidal antagonists in preclinical models. Five pharmaceutical companies have nonsteroidal MRAs in clinical development with a clear focus on the treatment of chronic kidney diseases. No clinical data have been published so far for MT-3995 (Mitsubishi), SC-3150 (Daiichi-Sankyo), LY2623091 (Eli Lilly) and PF-03882845 (Pfizer). In contrast, data from two clinical phase II trials are available for finerenone (Bayer) which demonstrated safety and efficacy in patients with heart failure and additional chronic kidney diseases, and significantly reduced albuminuria in patients with diabetic nephropathy. Neither hyperkalemia nor reductions in kidney function were limiting factors to its use. Novel, nonsteroidal MRAs are currently tested in clinical trials. Based on preclinical and first clinical data, these nonsteroidal MRAs might overcome the limitations of today's steroidal antagonists.

  3. AhR ligands, malassezin, and indolo[3,2-b]carbazole are selectively produced by Malassezia furfur strains isolated from seborrheic dermatitis.

    PubMed

    Gaitanis, George; Magiatis, Prokopios; Stathopoulou, Konstantina; Bassukas, Ioannis D; Alexopoulos, Evangelos C; Velegraki, Aristea; Skaltsounis, Alexios-Leandros

    2008-07-01

    Malassezia yeasts are connected with seborrheic dermatitis (SD) whereas M. furfur pathogenicity is associated with the production of bioactive indoles. In this study, the production of indoles by M. furfur isolates from healthy and diseased skin was compared, the respective HPLC patterns were analyzed, and substances that are preferentially synthesized by strains isolated from SD lesions were isolated and characterized. Malassezin, pityriacitrin, indole-3-carbaldehyde, and indolo[3,2-b]carbazole (ICZ) were isolated by HPLC from extracts of M. furfur grown in L-tryptophan agar, and identified by nuclear magnetic resonance and mass spectroscopy. Of these, ICZ, a potent ligand of the aryl hydrocarbon receptor (AhR), is described for the first time to our knowledge as a M. furfur metabolite. HPLC-photodiode array detection analysis of strain extracts from 7 healthy subjects and 10 SD patients showed that M. furfur isolates from only SD patients consistently produce malassezin and ICZ. This discriminatory production of AhR agonists provides initial evidence for a previously unreported mechanism triggering development of SD and indicates that the variable pathogenicity patterns recorded for M. furfur-associated SD conditions may be attributed to selective production (P<0.001) of measurable bioactive indoles.

  4. Polychlorinated biphenyls (PCBs) contamination and aryl hydrocarbon receptor (AhR) agonist activity of Omega-3 polyunsaturated fatty acid supplements: implications for daily intake of dioxins and PCBs.

    PubMed

    Bourdon, J A; Bazinet, T M; Arnason, T T; Kimpe, L E; Blais, J M; White, P A

    2010-11-01

    Omega-3 polyunsaturated fatty acid (n-3 PUFA) rich oils derived primarily from fish are frequently consumed as supplements. Due to the tendency of persistent organic pollutants (POPs) to accumulate in exposed organisms, n-3 PUFA supplements can contain sufficient POPs to present a risk to consumers. Here we investigated PCB concentrations and aryl hydrocarbon receptor (AhR) agonist activity in 17 n-3 PUFA supplements available in Canada. PCBs ranged from <0.8 to 793 ng g(-1) oil, with salmon- and seal-derived products yielding the highest values. AhR agonist activity from a reporter gene assay ranged from 1.3 to 72.2 pg TEQ g(-1) oil, with salmon and tuna yielding the highest values. When consumed at the recommended doses and as a supplement to the average Canadian diet, seal-derived oil can contribute to exceedance of the tolerable daily intake of 20 ng PCBs kg-BW(-1)day(-1), and salmon-, tuna-, and sea herring-derived oils can contribute to exceedance of the tolerable daily intake limit of 2.3 pg TEQ kg-BW(-1)day(-1). The beneficial properties of fish and n-3 PUFA supplements, and the results of this study suggest that it is prudent to consume supplements derived from small, cold-water fatty fish. Further research will be necessary to draw firm conclusions. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

  5. Examination of Zolpidem effects on AhR- and PXR-dependent expression of drug-metabolizing cytochromes P450 in primary cultures of human hepatocytes.

    PubMed

    Bachleda, Petr; Vrzal, Radim; Pivnicka, Jakub; Cvek, Boris; Dvorak, Zdenek

    2009-12-01

    A hypnotic drug Zolpidem is used in clinical practice for more than 25 years. Surprisingly, the effects of Zolpidem on the expression of drug-metabolizing cytochromes P450 (CYPs) were not examined yet. Recently, the unexpected capacity of several "old drugs", such as valproic acid or azoles, to induce CYPs was reported. Therefore, we tested whether Zolpidem induces the expression of important CYPs in primary cultures of human hepatocytes. Cells were treated for 24h with Zolpidem in therapeutic (0.1mg/L) and toxic (1mg/L) concentrations. The levels of CYP1A1, CYP1A2, CY2C9 and CYP3A4 mRNAs were not altered by Zolpidem, whereas model inducers dioxin and rifampicin significantly induced CYP1A and CYP2/3 gene expression, respectively. Consistently, Zolpidem did not activate aryl hydrocarbon receptor (AhR) and pregnane X receptor (PXR), the key regulators of cytochromes P450s, as revealed by transient transfection gene reporter assays using HepG2 cells. We conclude Zolpidem be considered a safe drug with respect to the possible interactions through AhR- and PXR-dependent induction of drug-metabolizing CYPs.

  6. Kynurenine promotes the goblet cell differentiation of HT-29 colon carcinoma cells by modulating Wnt, Notch and AhR signals.

    PubMed

    Park, Joo-Hung; Lee, Jeong-Min; Lee, Eun-Jin; Kim, Da-Jeong; Hwang, Won-Bhin

    2018-04-01

    Various amino acids regulate cell growth and differentiation. In the present study, we examined the ability of HT-29 cells to differentiate into goblet cells in RPMI and DMEM which are largely different in the amounts of numerous amino acids. Most of the HT-29 cells differentiated into goblet cells downregulating the stem cell marker Lgr5 when cultured in DMEM, but remained undifferentiated in RPMI. The goblet cell differentiation in DMEM was inhibited by 1-methyl-tryptophan (1-MT), an inhibitor of indoleamine 2,3 dioxygenase-1 which is the initial enzyme in tryptophan metabolism along the kynurenine (KN) pathway, whereas tryptophan and KN induced goblet cell differentiation in RPMI. The levels of Notch1 and its activation product Notch intracytoplasmic domain in HT-29 cells were lower in DMEM than those in RPMI and were increased by 1-MT in both media. HT-29 cells grown in both media expressed β-catenin at the same level on day 2 when goblet cell differentiation was not observed. β-catenin expression, which was increased by 1-MT in both media, was decreased by KN. DMEM reduced Hes1 expression while enhancing Hath1 expression. Finally, aryl hydrocarbon receptor (AhR) activation moderately induced goblet cell differentiation. Our results suggest that KN promotes goblet cell differentiation by regulating Wnt, Notch, and AhR signals and expression of Hes1 and Hath1.

  7. Dihydromethysticin (DHM) Blocks Tobacco Carcinogen 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-Induced O6-Methylguanine in a Manner Independent of the Aryl Hydrocarbon Receptor (AhR) Pathway in C57BL/6 Female Mice.

    PubMed

    Narayanapillai, Sreekanth C; Lin, Shang-Hsuan; Leitzman, Pablo; Upadhyaya, Pramod; Baglole, Carolyn J; Xing, Chengguo

    2016-11-21

    4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a key carcinogen responsible for tobacco smoke-induced lung carcinogenesis. Among the types of DNA damage caused by NNK and its metabolite, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), O 6 -methylguanine (O 6 -mG) is likely the most carcinogen in A/J mice. Results of our previous studies showed that levels of O 6 -mG and other types of NNAL-derived DNA damage were preferentially reduced in the lung of female A/J mice upon dietary treatment with dihydromethysticin (DHM), a promising lung cancer chemopreventive agent from kava. Such a differential blockage may be mediated via an increased level of NNAL glucuronidation, thereby leading to its detoxification. The potential of the aryl hydrocarbon receptor (AhR) as an upstream target of DHM mediating these events was evaluated herein using Ahr +/- and Ahr -/- C57BL/6 female mice because DHM was reported as an AhR agonist. DHM (0.05, 0.2, and 1.0 mg/g of diet) and dihydrokavain (DHK, an inactive analogue, 1.0 mg/g of diet) were given to mice for 7 days, followed by a single intraperitoneal dose of NNK at 100 mg/kg of body weight. The effects of DHM on the amount of O 6 -mG in the lung, on the urinary ratio of glucuronidated NNAL (NNAL-Gluc) and free NNAL, and on CYP1A1/2 activity in the liver microsomes were analyzed. As observed in A/J mice, DHM treatment significantly and dose-dependently reduced the level of O 6 -mG in the target lung tissue, but there were no significant differences in O 6 -mG reduction between mice from Ahr +/- and Ahr -/- backgrounds. Similarly, in both strains, DHM at 1 mg/g of diet significantly increased the urinary ratio of NNAL-Gluc to free NNAL and CYP1A1/2 enzymatic activity in liver with no changes detected at lower DHM dosages. Because none of these effects of DHM were dependent on Ahr status, AhR clearly is not the upstream target for DHM.

  8. Effects of human blood levels of two PAH mixtures on the AHR signalling activation pathway and CYP1A1 and COMT target genes in granulosa non-tumor and granulosa tumor cell lines.

    PubMed

    Zajda, Karolina; Ptak, Anna; Rak, Agnieszka; Fiedor, Elżbieta; Grochowalski, Adam; Milewicz, Tomasz; Gregoraszczuk, Ewa L

    2017-08-15

    Epidemiological studies have shown a link between problems with offspring of couples living in a contaminated environment in comparison to those who live in an uncontaminated environment. We measured the concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) in maternal and cord blood. To explore the mechanism of the effects of PAH mixtures on nonluteinized granulosa cells (HGrC1) and granulosa tumor cells (COV434), as well as cell proliferation and apoptosis, we investigated the effect of PAH mixtures on the expression of the aryl hydrocarbon receptor (AHR), aryl hydrocarbon receptor nuclear translocator (ARNT) and aryl hydrocarbon receptor repressor (AHRR) genes, as well as the expression and activity of target genes cytochrome P450 1A1 (CYP1A1) and catechol-O-methyltransferase (COMT). The cells were exposed to mixture 1 (M1), composed of all 16 priority PAHs, and mixture 2 (M2), composed of five PAHs which are not classified as human carcinogens, and which are observed in the highest amounts both in maternal and cord blood. All 16 priority PAHs were bioavailable in maternal and cord plasma, suggesting that perinatal exposure should be considered. In HGrC1 cells, M1 increased AHR and ARNT, but decreased AHRR expression, in parallel with increased CYP1A1 and COMT expression and activity. M2 decreased AHR and AHRR, and increased ARNT, with no effect on CYP1A1 expression and activity; however, it did increase COMT expression and activity. In tumor cells, M1 lowered AHR and up-regulated AHRR and ARNT expression, consequently decreasing CYP1A1 expression and COMT activity. M2 up-regulated AHR and ARNT, down-regulated AHRR, and had no effect on CYP1A1 and COMT expression, but decreased COMT activity. We hypothesise that, dependent on composition, mixtures of PAHs activate the AHR differently through varying transcription responses: in HGrC1, a canonical AHR mechanism of M1, with activation of CYP1A1 important for detoxication, while in COV434, a

  9. Combination decongestion therapy in hospitalized heart failure: loop diuretics, mineralocorticoid receptor antagonists and vasopressin antagonists.

    PubMed

    Vaduganathan, Muthiah; Mentz, Robert J; Greene, Stephen J; Senni, Michele; Sato, Naoki; Nodari, Savina; Butler, Javed; Gheorghiade, Mihai

    2015-01-01

    Congestion is the most common reason for admissions and readmissions for heart failure (HF). The vast majority of hospitalized HF patients appear to respond readily to loop diuretics, but available data suggest that a significant proportion are being discharged with persistent evidence of congestion. Although novel therapies targeting congestion should continue to be developed, currently available agents may be utilized more optimally to facilitate complete decongestion. The combination of loop diuretics, natriuretic doses of mineralocorticoid receptor antagonists and vasopressin antagonists represents a regimen of currently available therapies that affects early and persistent decongestion, while limiting the associated risks of electrolyte disturbances, hemodynamic fluctuations, renal dysfunction and mortality.

  10. Mortality Benefit of Recombinant Human Interleukin-1 Receptor Antagonist for Sepsis Varies by Initial Interleukin-1 Receptor Antagonist Plasma Concentration.

    PubMed

    Meyer, Nuala J; Reilly, John P; Anderson, Brian J; Palakshappa, Jessica A; Jones, Tiffanie K; Dunn, Thomas G; Shashaty, Michael G S; Feng, Rui; Christie, Jason D; Opal, Steven M

    2018-01-01

    Plasma interleukin-1 beta may influence sepsis mortality, yet recombinant human interleukin-1 receptor antagonist did not reduce mortality in randomized trials. We tested for heterogeneity in the treatment effect of recombinant human interleukin-1 receptor antagonist by baseline plasma interleukin-1 beta or interleukin-1 receptor antagonist concentration. Retrospective subgroup analysis of randomized controlled trial. Multicenter North American and European clinical trial. Five hundred twenty-nine subjects with sepsis and hypotension or hypoperfusion, representing 59% of the original trial population. Random assignment of placebo or recombinant human interleukin-1 receptor antagonist × 72 hours. We measured prerandomization plasma interleukin-1 beta and interleukin-1 receptor antagonist and tested for statistical interaction between recombinant human interleukin-1 receptor antagonist treatment and baseline plasma interleukin-1 receptor antagonist or interleukin-1 beta concentration on 28-day mortality. There was significant heterogeneity in the effect of recombinant human interleukin-1 receptor antagonist treatment by plasma interleukin-1 receptor antagonist concentration whether plasma interleukin-1 receptor antagonist was divided into deciles (interaction p = 0.046) or dichotomized (interaction p = 0.028). Interaction remained present across different predicted mortality levels. Among subjects with baseline plasma interleukin-1 receptor antagonist above 2,071 pg/mL (n = 283), recombinant human interleukin-1 receptor antagonist therapy reduced adjusted mortality from 45.4% to 34.3% (adjusted risk difference, -0.12; 95% CI, -0.23 to -0.01), p = 0.044. Mortality in subjects with plasma interleukin-1 receptor antagonist below 2,071 pg/mL was not reduced by recombinant human interleukin-1 receptor antagonist (adjusted risk difference, +0.07; 95% CI, -0.04 to +0.17), p = 0.230. Interaction between plasma interleukin-1 beta concentration and recombinant human

  11. Update in TSH Receptor Agonists and Antagonists

    PubMed Central

    Neumann, Susanne

    2012-01-01

    The physiological role of the TSH receptor (TSHR) as a major regulator of thyroid function is well understood, but TSHRs are also expressed in multiple normal extrathyroidal tissues, and the physiological roles of TSHRs in these tissues are unclear. Moreover, TSHRs play a major role in several pathological conditions including hyperthyroidism, hypothyroidism, and thyroid tumors. Small molecule, “drug-like” TSHR agonists, neutral antagonists, and inverse agonists may be useful as probes of TSHR function in extrathyroidal tissues and as leads to develop drugs for several diseases of the thyroid. In this Update, we review the most recent findings regarding the development and use of these small molecule TSHR ligands. PMID:23019348

  12. Agonists and antagonists for P2 receptors

    PubMed Central

    Jacobson, Kenneth A.; Costanzi, Stefano; Joshi, Bhalchandra V.; Besada, Pedro; Shin, Dae Hong; Ko, Hyojin; Ivanov, Andrei A.; Mamedova, Liaman

    2015-01-01

    Recent work has identified nucleotide agonists selective for P2Y1, P2Y2 and P2Y6 receptors and nucleotide antagonists selective for P2Y1, P2Y12 and P2X1 receptors. Selective non-nucleotide antagonists have been reported for P2Y1, P2Y2, P2Y6, P2Y12, P2Y13, P2X2/3/P2X3 and P2X7 receptors. For example, the dinucleotide INS 37217 (Up4dC) potently activates the P2Y2 receptor, and the non-nucleotide antagonist A-317491 is selective for P2X2/3/P2X3 receptors. Nucleotide analogues in which the ribose moiety is substituted by a variety of novel ring systems, including conformation-ally locked moieties, have been synthesized as ligands for P2Y receptors. The focus on conformational factors of the ribose-like moiety allows the inclusion of general modifications that lead to enhanced potency and selectivity. At P2Y1,2,4,11 receptors, there is a preference for the North conformation as indicated with (N)-methanocarba analogues. The P2Y1 antagonist MRS2500 inhibited ADP-induced human platelet aggregation with an IC50 of 0.95 nM. MRS2365, an (N)-methanocarba analogue of 2-MeSADP, displayed potency (EC50) of 0.4 nM at the P2Y1 receptor, with >10 000-fold selectivity in comparison to P2Y12 and P2Y13 receptors. At P2Y6 receptors there is a dramatic preference for the South conformation. Three-dimensional structures of P2Y receptors have been deduced from structure activity relationships (SAR), mutagenesis and modelling studies. Detailed three-dimensional structures of P2X receptors have not yet been proposed. PMID:16805423

  13. MMP-12-mediated by SARM-TRIF signaling pathway contributes to IFN-γ-independent airway inflammation and AHR post RSV infection in nude mice.

    PubMed

    Long, Xiaoru; Li, Simin; Xie, Jun; Li, Wei; Zang, Na; Ren, Luo; Deng, Yu; Xie, Xiaohong; Wang, Lijia; Fu, Zhou; Liu, Enmei

    2015-02-05

    Respiratory syncytial virus (RSV) is one of the most frequently observed pathogens during infancy and childhood. However, the corresponding pathogenesis has not been determined to date. We previously demonstrated that IFN-γ plays an important role in RSV pathogenesis, and SARM-TRIF-signaling pathway could regulate the production of IFN-γ. This study is to investigate whether T cells or innate immune cells are the predominant producers of IFN-γ, and further to explore other culprits in addition to IFN-γ in the condition of RSV infection. Normal BALB/c mice and nude mice deficient in T cells were infected intranasally with RSV. Leukocytes in bronchoalveolar lavage fluid were counted, lung histopathology was examined, and airway hyperresponsiveness (AHR) was measured by whole-body plethysmography. IFN-γ and MMP-12 were detected by ELISA. MMP408, a selective MMP-12 inhibitor, was given intragastrically. Resveratrol, IFN-γ neutralizing antibody and recombinant murine IFN-γ were administered intraperitoneally. SARM and TRIF protein were semi-quantified by Western blot. siRNA was used to knock-down SARM expression. RSV induced significant airway inflammation and AHR in both mice; IFN-γ was significantly increased in BALB/c mice but not in nude mice. MMP-12 was dramatically increased in both mice but earlier in nude mice. When MMP-12 was inhibited by MMP408, RSV-induced respiratory symptoms were alleviated. SARM was significantly suppressed while TRIF was significantly enhanced in both mice strains. Following resveratrol administration in nude mice, 1) SARM inhibition was prevented, 2) TRIF and MMP-12 were correspondingly down-regulated and 3) airway disorders were subsequently alleviated. Moreover, when SARM was efficiently knocked down using siRNA, TRIF and MMP-12 were markedly enhanced, and the anti-RSV effects of resveratrol were remarkably abrogated. MMP-12 was significantly increased in the IFN-γ neutralizing antibody-treated BALB/c mice but reduced in the

  14. Cytochrome P4501A induction in avian hepatocyte cultures exposed to polychlorinated biphenyls: Comparisons with AHR1-mediated reporter gene activity and in ovo toxicity

    SciTech Connect

    Manning, Gillian E., E-mail: gmann017@uottawa.ca; Environment Canada, National Wildlife Research Centre, Ottawa, ON, Canada K1A 0H3; Mundy, Lukas J., E-mail: lukas.mundy@ec.gc.ca

    2013-01-01

    Avian-specific toxic equivalency factors (TEFs) were developed by the World Health Organization to simplify environmental risk assessments of dioxin-like compounds (DLCs), but TEFs do not account for differences in the toxic and biochemical potencies of DLCs among species of birds. Such variability may be due to differences in species sensitivity to individual DLCs. The sensitivity of avian species to DLCs was recently associated with the identity of amino acids 324 and 380 in the aryl hydrocarbon receptor 1 (AHR1) ligand binding domain. A luciferase reporter gene (LRG) assay, measuring AHR1-mediated induction of a cytochrome P450 1A5 (CYP1A5) reporter gene, inmore » combination with a species' AHR1 ligand binding domain sequence, were also shown to predict avian species sensitivity to polychlorinated biphenyls (PCBs) and PCB relative potency in a given species. The goals of the present study were to (1) characterize the concentration-dependent effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin and PCBs 126, 77, 105 and 118 on induction of ethoxyresorufin O-deethylase (EROD) activity and CYP1A4/5 mRNA in chicken, ring-necked pheasant and Japanese quail embryo hepatocytes and (2) compare these in vitro results to those previously generated by the LRG assay and in ovo toxicity studies. EROD activity and CYP1A4/5 mRNA expression data support and complement the findings of the LRG assay. CYP1A enzyme activity and mRNA expression were significantly correlated both with luciferase activity and in ovo toxicity induced by PCBs. Relative potency values were generally similar between the LRG and EROD assays and indicate that the relative potency of some PCBs may differ among species. -- Highlights: ► The chicken isn't the most sensitive species to CYP1A induction by PCB 105 and 118. ► The relative potency of PCBs differs between avian species. ► EROD activity was correlated with luciferase activity from the LRG assay. ► EROD activity was a better predictor of toxicity

  15. Use of the mouse jumping test for estimating antagonistic potencies of morphine antagonists.

    PubMed

    Cowan, A

    1976-03-01

    The potencies of 19 reference morphine antagonists have been compared in a modified version of the mouse jumping test. Mice were each implanted subcutaneously with one 75 mg pellet of morphine. Antagonist challenge took place 72 h later and the incidence of repetitive vertical-jumping was monitored over 1 h. A high Pearson correlation coefficient (r = 0.997) was found between quantitative assays based on the total number of jumps per mouse and quantal assays based on mice jumping at least 6 times. A comparison of relative potencies obtained with the mouse test and with non-withdrawn morphine-dependent monkeys gave a Spearman rank order coefficient of 0.91 while a similar comparison with values obtained with the guinea-pig isolated ileum preparation also gave a high correlation coefficient (r= 0.92). Whereas it is difficult to assess the antagonistic component of buprenorphine and cyclorphan with the ileum preparation, both compounds can be satisfactorily assayed in the mouse jumping test. The reported antagonistic properties of ketocyclazocine and profadol could not be confirmed in the mouse model.

  16. Screening of antagonistic bacteria isolated from Amorphophallus konjac rhizosphere soil

    NASA Astrophysics Data System (ADS)

    Lin, Tianxing; Gong, Mingfu; Guan, Qinlan; Huang, Ying; Qin, Fang

    2018-04-01

    Bacteria lived in Amorphaphallus konjac rhizosphere soil have the potential ability of antagonistic bacterial pathogen activity against to Erwinia carotovora subsp carotovora (Ecc). The paper was to study and analyze all strains of 18 bacteria isolated from A. konjac rhizosphere soil with strong antagonistic effect against to Ecc and to identify antagonistic bacteria with morphology, physiology and biochemistry characteristic. The antagonistic bacterial pathogen activity of different bacterial strains were significantly different. Five of 18 strains isolated from A. konjac rhizosphere soil, including AKSB03, AKSB05, AKSB08, AKSB13 and AKSB16 was screened with antagonistic wider more than 15 mm in first screening test. Strain AKSB08 and strain AKSB16 had a strong antagonism activity for Ecc with antagonistic wider more than 20 mm in second screening test. Strain AKSB08 and strain AKSB16 belonged to Bacillus with morphology, physiology and biochemistry characteristic.

  17. Sexually Antagonistic Selection in Human Male Homosexuality

    PubMed Central

    Camperio Ciani, Andrea; Cermelli, Paolo; Zanzotto, Giovanni

    2008-01-01

    Several lines of evidence indicate the existence of genetic factors influencing male homosexuality and bisexuality. In spite of its relatively low frequency, the stable permanence in all human populations of this apparently detrimental trait constitutes a puzzling ‘Darwinian paradox’. Furthermore, several studies have pointed out relevant asymmetries in the distribution of both male homosexuality and of female fecundity in the parental lines of homosexual vs. heterosexual males. A number of hypotheses have attempted to give an evolutionary explanation for the long-standing persistence of this trait, and for its asymmetric distribution in family lines; however a satisfactory understanding of the population genetics of male homosexuality is lacking at present. We perform a systematic mathematical analysis of the propagation and equilibrium of the putative genetic factors for male homosexuality in the population, based on the selection equation for one or two diallelic loci and Bayesian statistics for pedigree investigation. We show that only the two-locus genetic model with at least one locus on the X chromosome, and in which gene expression is sexually antagonistic (increasing female fitness but decreasing male fitness), accounts for all known empirical data. Our results help clarify the basic evolutionary dynamics of male homosexuality, establishing this as a clearly ascertained sexually antagonistic human trait. PMID:18560521

  18. Ploidally antagonistic selection maintains stable genetic polymorphism.

    PubMed

    Immler, Simone; Arnqvist, Göran; Otto, Sarah Perin

    2012-01-01

    Understanding the maintenance of genetic variation in the face of selection remains a key issue in evolutionary biology. One potential mechanism for the maintenance of genetic variation is opposing selection during the diploid and haploid stages of biphasic life cycles universal among eukaryotic sexual organisms. If haploid and diploid gene expression both occur, selection can act in each phase, potentially in opposing directions. In addition, sex-specific selection during haploid phases is likely simply because male and female gametophytes/gametes tend to have contrasting life histories. We explored the potential for the maintenance of a stable polymorphism under ploidally antagonistic as well as sex-specific selection. Furthermore, we examined the role of the chromosomal location of alleles (autosomal or sex-linked). Our analyses show that the most permissible conditions for the maintenance of polymorphism occur under negative ploidy-by-sex interactions, where stronger selection for an allele in female than male diploids is coupled with weaker selection against the allele in female than male haploids. Such ploidy-by-sex interactions also promote allele frequency differences between the sexes. With constant fitness, ploidally antagonistic selection can maintain stable polymorphisms for autosomal and X-linked genes but not for Y-linked genes. We discuss the implications of our results and outline a number of biological settings where the scenarios modeled may apply. © 2011 The Author(s). Evolution © 2011 The Society for the Study of Evolution.

  19. Therapeutic perspectives for melatonin agonists and antagonists.

    PubMed

    Delagrange, P; Atkinson, J; Boutin, J A; Casteilla, L; Lesieur, D; Misslin, R; Pellissier, S; Pénicaud, L; Renard, P

    2003-04-01

    Melatonin is a neurohormone synthesized in the pineal gland during the dark period in all species, including humans. The diversity and differences in melatonin receptor distribution in the brain and extracerebral organs suggest multiple functional roles for melatonin. Administration of melatonin agonists reduces neophobia and treatment with a melatonin antagonist during the dark period reverses the anxiolytic-like effect of endogenous melatonin. Chronic treatment with agonists prevents various perturbations induced by chronic mild stress. Melatonin in vivo directly constricts cerebral arterioles in rats and decreases the lower limit of cerebral blood flow autoregulation, suggesting that melatonin may diminish the risk of hypoperfusion-induced cerebral ischemia. At the extracerebral level, melatonin regulates intestinal motility in rats. The intestinal postprandial motor response is shorter in the dark phase than in the light phase and this reduction is reversed in animals pretreated with a melatonin antagonist. Moreover, melatonin reduces the duration of cholecystokinin excitomotor effect. Endogenous melatonin may modulate intestinal motility to coordinate intestinal functions such as digestion and transit and control the metabolism of the animal. An adipocyte melatonin binding site may also participate in this control. Melatonin is involved in a wide range of physiological functions. The question remains as to whether evolution, adaptation and diurnal life have modified the physiological role of melatonin in humans. Moreover, the functional role of each of the receptor subtypes has to be characterized to design selective ligands to treat specific diseases.

  20. Perturbation effect of reduced graphene oxide quantum dots (rGOQDs) on aryl hydrocarbon receptor (AhR) pathway in zebrafish.

    PubMed

    Zhang, Jing-Hui; Sun, Tai; Niu, Aping; Tang, Yu-Mei; Deng, Shun; Luo, Wei; Xu, Qun; Wei, Dapeng; Pei, De-Sheng

    2017-07-01

    Graphene quantum dots (GQDs) has been widely used in enormous fields, however, the inherent molecular mechanism of GQDs for potential risks in biological system is still elusive to date. In this study, the outstanding reduced graphene quantum dots (rGOQDs) with the QY as high as 24.62% were successfully synthesized by the improved Hummers method and DMF hydrothermal treatment approach. The rGOQDs were N-doped photoluminescent nanomaterials with functional groups on the surface. The fluorescent bio-imaging was performed by exposing zebrafish in different concentrations of the as-prepared rGOQDs, and the distribution of rGOQDs was successfully observed. Moreover, the developmental toxicity and genotoxicity were evaluated to further investigate the potential hazard of rGOQDs. The result indicated that rGOQDs were responsible for the dose-dependent abnormalities on the development of zebrafish. Since the real-time polymerase chain reaction (RT-PCR) results showed that the expression of cyp1a was the highest expression in the selected genes and significantly up-regulated 8.49 fold in zebrafish, the perturbation of rGOQDs on aryl hydrocarbon receptor (AhR) pathway was investigated by using the Tg(cyp1a:gfp) zebrafish for the first time. The results demonstrated that rGOQDs significantly increased the green fluorescent protein (GFP) expression promoted by cyp1a in a dose-dependent manner, which was also further confirmed by the western blotting. This study offered an opportunity to reveal the potential hazards of in vivo bio-probes, which provided a valuable reference for investigating the graphene-based materials on the disturbance of AhR pathway in biological organisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. AhR activation increases IL-2 production by alloreactive CD4+ T cells initiating the differentiation of mucosal-homing Tim3+ Lag3+ Tr1 cells.

    PubMed

    Ehrlich, Allison K; Pennington, Jamie M; Tilton, Susan; Wang, Xisheng; Marshall, Nikki B; Rohlman, Diana; Funatake, Castle; Punj, Sumit; O'Donnell, Edmond; Yu, Zhen; Kolluri, Siva K; Kerkvliet, Nancy I

    2017-11-01

    Activation of the aryl hydrocarbon receptor (AhR) by immunosuppressive ligands promotes the development of regulatory T (Treg) cells. Although AhR-induced Foxp3 + Treg cells have been well studied, much less is known about the development and fate of AhR-induced Type 1 Treg (AhR-Tr1) cells. In the current study, we identified the unique transcriptional and functional changes in murine CD4 + T cells that accompany the differentiation of AhR-Tr1 cells during the CD4 + T-cell-dependent phase of an allospecific cytotoxic T lymphocyte (allo-CTL) response. AhR activation increased the expression of genes involved in T-cell activation, immune regulation and chemotaxis, as well as a global downregulation of genes involved in cell cycling.  Increased IL-2 production was responsible for the early AhR-Tr1 activation phenotype previously characterized as CD25 + CTLA4 + GITR + on day 2. The AhR-Tr1 phenotype was further defined by the coexpression of the immunoregulatory receptors Lag3 and Tim3 and non-overlapping expression of CCR4 and CCR9. Consistent with the increased expression of CCR9, real-time imaging showed enhanced migration of AhR-Tr1 cells to the lamina propria of the small intestine and colon. The discovery of mucosal imprinting of AhR-Tr1 cells provides an additional mechanism by which therapeutic AhR ligands can control immunopathology. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Immuno-detection of dioxins using a recombinant protein of aryl hydrocarbon receptor (AhR) fused with sfGFP.

    PubMed

    Faiad, Walaa; Hanano, Abdulsamie; Kabakibi, Mohamed Maher; Abbady, Abdul Qader

    2016-06-21

    Dioxins are one of the most toxic groups of persistent organic pollutants. Their bioaccumulation through the food chain constitutes a potential risk for human health. Upon cell entry, dioxins bind specifically and firmly to the aryl hydrocarbon receptor (AhR), leading to the stimulation of several enzymes responsible for its detoxification. Dioxin/AhR interaction could be exploited as an affordable alternative to a variety of analytical methods for detecting dioxin contamination in the environment. In this work, the ligand binding domain (LBD) of the AhR was cloned downstream a superfolder form of the green fluorescent protein (sfGFP), resulting in the construct pRSET-sfGFP-AhR. High level of expressed sfGFP-AhR fusion protein (50 kDa) was recovered from the inclusion bodies of E. coli by simple solubilization with the Arginine, and purified by affinity chromatography via its N-terminal 6 × His tag. Its purity was confirmed by SDS-PAGE analysis and immunoblotting with anti-His or anti-GFP antibodies. Indirect ELISA revealed the ability of the sfGFP-AhR, but not the sfGFP, to bind to the immobilized dioxin with the possibility to detect such interaction by both its 6 × His and GFP tags,Competitive ELISA showed that anti-dioxin antibody was more sensitive to low dioxin concentrations than sfGFP-AhR. Nevertheless,the detection range of sfGFP-AhR fusion was much wider and the detection limit was of about 10 ppt (parts per trillion) of free dioxin in the tested artificial samples. this highly expressed and functional sfGFP-AhR fusion protein provides a promising molecular tool for detecting and quantifying different congeners of dioxins.

  3. Corticospinal control of antagonistic muscles in the cat.

    PubMed

    Ethier, Christian; Brizzi, Laurent; Giguère, Dominic; Capaday, Charles

    2007-09-01

    We recently suggested that movement-related inter-joint muscle synergies are recruited by selected excitation and selected release from inhibition of cortical points. Here we asked whether a similar cortical mechanism operates in the functional linking of antagonistic muscles. To this end experiments were done on ketamine-anesthetized cats. Intracortical microstimulation (ICMS) and intramuscular electromyographic recordings were used to find and characterize wrist, elbow and shoulder antagonistic motor cortical points. Simultaneous ICMS applied at two cortical points, each evoking activity in one of a pair of antagonistic muscles, produced co-contraction of antagonistic muscle pairs. However, we found an obvious asymmetry in the strength of reciprocal inhibition; it was always significantly stronger on physiological extensors than flexors. Following intravenous injection of a single bolus of strychnine, a cortical point at which only a physiological flexor was previously activated also elicited simultaneous activation of its antagonist. This demonstrates that antagonistic corticospinal neurons are closely grouped, or intermingled. To test whether releasing a cortical point from inhibition allows it to be functionally linked with an antagonistic cortical point, one of three GABA(A) receptor antagonists, bicuculline, gabazine or picrotoxin, was injected iontophoretically at one cortical point while stimulation was applied to an antagonistic cortical point. This coupling always resulted in co-contraction of the represented antagonistic muscles. Thus, antagonistic motor cortical points are linked by excitatory intracortical connections held in check by local GABAergic inhibition, with reciprocal inhibition occurring at the spinal level. Importantly, the asymmetry of cortically mediated reciprocal inhibition would appear significantly to bias muscle maps obtained by ICMS in favor of physiological flexors.

  4. Elucidating the Role of CD84 and AHR in Modulation of LPS-Induced Cytokines Production by Cruciferous Vegetable-Derived Compounds Indole-3-Carbinol and 3,3′-Diindolylmethane

    PubMed Central

    Wang, Thomas T. Y.; Pham, Quynhchi; Kim, Young S.

    2018-01-01

    Modulation of the immune system by cancer protective food bioactives has preventive and therapeutic importance in prostate cancer, but the mechanisms remain largely unclear. The current study tests the hypothesis that the diet-derived cancer protective compounds, indole-3-carbinol (I3C) and 3,3′-diindolylmethane (DIM), affect the tumor microenvironment by regulation of inflammatory responses in monocytes and macrophages. We also ask whether I3C and DIM act through the aryl hydrocarbon (AHR)-dependent pathway or the signaling lymphocyte activation molecule (SLAM) family protein CD84-mediated pathway. The effect of I3C and DIM was examined using the human THP-1 monocytic cell in its un-differentiated (monocyte) and differentiated (macrophage) state. We observed that I3C and DIM inhibited lipopolysaccharide (LPS) induction of IL-1β mRNA and protein in the monocyte form but not the macrophage form of THP-1. Interestingly, CD84 mRNA but not protein was inhibited by I3C and DIM. AHR siRNA knockdown experiments confirmed that the inhibitory effects of I3C and DIM on IL-1β as well as CD84 mRNA are regulated through AHR-mediated pathways. Additionally, the AHR ligand appeared to differentially regulate other LPS-induced cytokines expression. Hence, cross-talk between AHR and inflammation-mediated pathways, but not CD84-mediated pathways, in monocytes but not macrophages may contribute to the modulation of tumor environments by I3C and DIM in prostate cancer. PMID:29364159

  5. AHR-related activities in a creosote-adapted population of adult atlantic killifish, Fundulus heteroclitus, two decades post-EPA superfund status at the Atlantic Wood Site, Portsmouth, VA USA.

    PubMed

    Wojdylo, Josephine V; Vogelbein, Wolfgang; Bain, Lisa J; Rice, Charles D

    2016-08-01

    Atlantic killifish, Fundulus heteroclitus, are adapted to creosote-based PAHs at the US EPA Superfund site known as Atlantic Wood (AW) on the southern branch of the Elizabeth River, VA USA. Subsequent to the discovery of the AW population in the early 1990s, these fish were shown to be recalcitrant to CYP1A induction by PAHs under experimental conditions, and even to the time of this study, killifish embryos collected from the AW site are resistant to developmental deformities typically associated with exposure to PAHs in reference fish. Historically, however, 90 +% of the adult killifish at this site have proliferative hepatic lesions including cancer of varying severity. Several PAHs at this site are known to be ligands for the aryl hydrocarbon receptor (AHR). In this study, AHR-related activities in AW fish collected between 2011 and 2013 were re-examined nearly 2 decades after first discovery. This study shows that CYP1A mRNA expression is three-fold higher in intestines of AW killifish compared to a reference population. Using immunohistochemistry, CYP1A staining in intestines was uniformly positive compared to negative staining in reference fish. Livers of AW killifish were examined by IHC to show that CYP1A and AHR2 protein expression reflect lesions-specific patterns, probably representing differences in intrinsic cellular physiology of the spectrum of proliferative lesions comprising the hepatocarcinogenic process. We also found that COX2 mRNA expression levels were higher in AW fish livers compared to those in the reference population, suggesting a state of chronic inflammation. Overall, these findings suggest that adult AW fish are responsive to AHR signaling, and do express CYP1A and AHR2 proteins in intestines at a level above what was observed in the reference population. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. AHR-related Activities in a Creosote-Adapted Population of Adult Atlantic Killifish, Fundulus heteroclitus, Two Decades Post-EPA Superfund Status at the Atlantic Wood Site, Portsmouth, VA USA

    PubMed Central

    Wojdylo, Josephine V.; Vogelbein, Wolfgang; Bain, Lisa J.; Rice, Charles D.

    2016-01-01

    Atlantic killifish, Fundulus heteroclitus, are adapted to creosote-based PAHs at the US EPA Superfund site known as Atlantic Wood (AW) on the southern branch of the Elizabeth River, VA USA. Subsequent to the discovery of the AW population in the early 1990s, these fish were shown to be recalcitrant to CYP1A induction by PAHs under experimental conditions, and even to the time of this study, killifish embryos collected from the AW site are resistant to developmental deformities typically associated with exposure to PAHs in reference fish. Historically, however, 90+% of the adult killifish at this site have proliferative hepatic lesions including cancer of varying severity. Several PAHs at this site are known to be ligands for the aryl hydrocarbon receptor (AHR). In this study, AHR-related activities in AW fish collected between 2011–2013 were re-examined nearly 2 decades after first discovery. This study shows that CYP1A mRNA expression is three-fold higher in intestines of AW killifish compared to a reference population. Using immunohistochemistry, CYP1A staining in intestines was uniformly positive compared to negative staining in reference fish. Livers of AW killifish were examined by IHC to show that CYP1A and AHR2 protein expression reflect lesions-specific patterns, probably representing differences in intrinsic cellular physiology of the spectrum of proliferative lesions comprising the hepatocarcinogenic process. We also found that COX2 mRNA expression levels were higher in AW fish livers compared to those in the reference population, suggesting a state of chronic inflammation. Overall, these findings suggest that adult AW fish are responsive to AHR signaling, and do express CYP1A and AHR2 proteins in intestines at a level above what was observed in the reference population. PMID:27262937

  7. Pervasive antagonistic interactions among hybrid incompatibility loci

    PubMed Central

    Josway, Sarah

    2017-01-01

    Species barriers, expressed as hybrid inviability and sterility, are often due to epistatic interactions between divergent loci from two lineages. Theoretical models indicate that the strength, direction, and complexity of these genetic interactions can strongly affect the expression of interspecific reproductive isolation and the rates at which new species evolve. Nonetheless, empirical analyses have not quantified the frequency with which loci are involved in interactions affecting hybrid fitness, and whether these loci predominantly interact synergistically or antagonistically, or preferentially involve loci that have strong individual effects on hybrid fitness. We systematically examined the prevalence of interactions between pairs of short chromosomal regions from one species (Solanum habrochaites) co-introgressed into a heterospecific genetic background (Solanum lycopersicum), using lines containing pairwise combinations of 15 chromosomal segments from S. habrochaites in the background of S. lycopersicum (i.e., 95 double introgression lines). We compared the strength of hybrid incompatibility (either pollen sterility or seed sterility) expressed in each double introgression line to the expected additive effect of its two component single introgressions. We found that epistasis was common among co-introgressed regions. Interactions for hybrid dysfunction were substantially more prevalent in pollen fertility compared to seed fertility phenotypes, and were overwhelmingly antagonistic (i.e., double hybrids were less unfit than expected from additive single introgression effects). This pervasive antagonism is expected to attenuate the rate at which hybrid infertility accumulates among lineages over time (i.e., giving diminishing returns as more reproductive isolation loci accumulate), as well as decouple patterns of accumulation of sterility loci and hybrid incompatibility phenotypes. This decoupling effect might explain observed differences between pollen and

  8. Antagonistic and Bargaining Games in Optimal Marketing Decisions

    ERIC Educational Resources Information Center

    Lipovetsky, S.

    2007-01-01

    Game theory approaches to find optimal marketing decisions are considered. Antagonistic games with and without complete information, and non-antagonistic games techniques are applied to paired comparison, ranking, or rating data for a firm and its competitors in the market. Mix strategy, equilibrium in bi-matrix games, bargaining models with…

  9. Adverse cutaneous reactions induced by TNF-alpha antagonist therapy.

    PubMed

    Borrás-Blasco, Joaquín; Navarro-Ruiz, Andrés; Borrás, Consuelo; Casterá, Elvira

    2009-11-01

    To review adverse cutaneous drug reactions induced by tumor necrosis factor alpha (TNF-alpha) antagonist therapy. A literature search was performed using PubMed (1996-March 2009), EMBASE, and selected MEDLINE Ovid bibliography searches. All language clinical trial data, case reports, letters, and review articles identified from the data sources were used. Since the introduction of TNF-alpha antagonist, the incidence of adverse cutaneous drug reactions has increased significantly. A wide range of different skin lesions might occur during TNF-alpha antagonist treatment. New onset or exacerbation of psoriasis has been reported in patients treated with TNF-alpha antagonists for a variety of rheumatologic conditions. TNF-alpha antagonist therapy has been associated with a lupus-like syndrome; most of these case reports occurred in patients receiving either etanercept or infliximab. Serious skin reactions such as erythema multiforme, Stevens-Johnson syndrome, and toxic epidermal necrolysis have been reported rarely with the use of TNF-alpha antagonists. As the use of TNF-alpha antagonists continues to increase, the diagnosis and management of cutaneous side effects will become an increasingly important challenge. In patients receiving TNF-alpha antagonist treatment, skin disease should be considered, and clinicians need to be aware of the adverse reactions of these drugs.

  10. The kinetics of competitive antagonists on guinea-pig ileum.

    PubMed Central

    Roberts, F; Stephenson, R P

    1976-01-01

    1 The kinetics of action of some competitive muscarinic and histamine antagonists were examined on guinea-pig isolated ileum and their behaviour compared with the predictions of the interaction-limited model described by Paton (1961). 2 The kinetics of antagonism were not consistent with the predictions of this model: (1) The apparent dissociation rate constant calculated from the decrease in occupancy on washout was not independent of the concentration of antagonist. (2) The dissociation rate constant of a 'slow' antagonist calculated from the change in occupancy when a 'fast' antagonist was superimposed varied with the concentration of fast antagonist. (3) If the concentration of slow antagonist was increased when the fast antagonist was superimposed so that the equilibrium occupancy of the 'slow' was the same as before, a transitional phase was observed. 3 The kinetics of antagonism were observed in longitudinal muscle strips and intact pieces of ileum, bathed in Tyrode or Krebs solution, and with isometric and isotonic recording. No evidence was found that the discrepancies between the interaction-limited model and the observed kinetics could be accounted for by the experimental method used. 4 It is therefore concluded that either access is rate-limiting in these circumstances or, if interaction is rate-limiting, some alternative interaction-limited model is required to describe the kinetics of antagonism. In either case it would seem unwise at this time to calculate antagonist-receptor rate constants from the observed kinetics of antagonism. PMID:974378

  11. Interaction between Antagonist of Cannabinoid Receptor and Antagonist of Adrenergic Receptor on Anxiety in Male Rat.

    PubMed

    Komaki, Alireza; Abdollahzadeh, Fatemeh; Sarihi, Abdolrahman; Shahidi, Siamak; Salehi, Iraj

    2014-01-01

    Anxiety is among the most common and treatable mental disorders. Adrenergic and cannabinoid systems have an important role in the neurobiology of anxiety. The elevated plus-maze (EPM) has broadly been used to investigate anxiolytic and anxiogenic compounds. The present study investigated the effects of intraperitoneal (IP) injection of cannabinoid CB1 receptor antagonist (AM251) in the presence of alpha-1 adrenergic antagonist (Prazosin) on rat behavior in the EPM. In this study, the data were obtained from male Wistar rat, which weighing 200- 250 g. Animal behavior in EPM were videotaped and saved in computer for 10 min after IP injection of saline, AM251 (0.3 mg/kg), Prazosin (0.3 mg/kg) and AM251 + Prazosin, subsequently scored for conventional indices of anxiety. During the test period, the number of open and closed arms entries, the percentage of entries into the open arms of the EPM, and the spent time in open and closed arms were recorded. Diazepam was considered as a positive control drug with anxiolytic effect (0.3, 0.6, 1.2 mg/kg). Diazepam increased the number of open arm entries and the percentage of spent time on the open arms. IP injection of AM251 before EPM trial decreased open arms exploration and open arm entry. Whereas, Prazosin increased open arms exploration and open arm entry. This study showed that both substances in simultaneous injection have conflicting effects on the responses of each of these two compounds in a single injection. Injection of CB1 receptor antagonist may have an anxiogenic profile in rat, whereas adrenergic antagonist has an anxiolytic effect. Further investigations are essential for better understanding of anxiolytic and anxiogenic properties and neurobiological mechanisms of action and probable interactions of the two systems.

  12. Stimulant effects of adenosine antagonists on operant behavior: differential actions of selective A2A and A1 antagonists

    PubMed Central

    Randall, Patrick A.; Nunes, Eric J.; Janniere, Simone L.; Stopper, Colin M.; Farrar, Andrew M.; Sager, Thomas N.; Baqi, Younis; Hockemeyer, Jörg; Müller, Christa E.

    2012-01-01

    Rationale Adenosine A2A antagonists can reverse many of the behavioral effects of dopamine antagonists, including actions on instrumental behavior. However, little is known about the effects of selective adenosine antagonists on operant behavior when these drugs are administered alone. Objective The present studies were undertaken to investigate the potential for rate-dependent stimulant effects of both selective and nonselective adenosine antagonists. Methods Six drugs were tested: two nonselective adenosine antagonists (caffeine and theophylline), two adenosine A1 antagonists (DPCPX and CPT), and two adenosine A2A antagonists (istradefylline (KW6002) and MSX-3). Two schedules of reinforcement were employed; a fixed interval 240-s (FI-240 sec) schedule was used to generate low baseline rates of responding and a fixed ratio 20 (FR20) schedule generated high rates. Results Caffeine and theophylline produced rate-dependent effects on lever pressing, increasing responding on the FI-240 sec schedule but decreasing responding on the FR20 schedule. The A2A antagonists MSX-3 and istradefylline increased FI-240 sec lever pressing but did not suppress FR20 lever pressing in the dose range tested. In fact, there was a tendency for istradefylline to increase FR20 responding at a moderate dose. A1 antagonists failed to increase lever pressing rate, but DPCPX decreased FR20 responding at higher doses. Conclusions These results suggest that adenosine A2A antagonists enhance operant response rates, but A1 antagonists do not. The involvement of adenosine A2A receptors in regulating aspects of instrumental response output and behavioral activation may have implications for the treatment of effort-related psychiatric dysfunctions, such as psychomotor slowing and anergia in depression. PMID:21347642

  13. On the simultaneous action of two competitive antagonists

    PubMed Central

    Ginsborg, B.L.; Stephenson, R.P.

    1974-01-01

    1 A hypothesis is outlined predicting the conditions in which the addition of a second competitive antagonist will increase rather than reduce the response to an agonist. 2 Experiments were performed with the guinea-pig ileum as the test tissue, hexyltrimethyl ammonium as the agonist, benzilyltropine methiodide as the `slow' antagonist and pentyltriethyl ammonium as the `fast' antagonist. 3 The results are consistent with the hypothesis, if the affinity constant for hexyltrimethyl ammonium is between 2.7 and 3.7 × 104 M-1, if the dissociation time constant for the slow antagonist is greater than 10 min and if that for the fast antagonist is less than 10 seconds. PMID:4451745

  14. Prostanoid receptor antagonists: development strategies and therapeutic applications

    PubMed Central

    Jones, RL; Giembycz, MA; Woodward, DF

    2009-01-01

    Identification of the primary products of cyclo-oxygenase (COX)/prostaglandin synthase(s), which occurred between 1958 and 1976, was followed by a classification system for prostanoid receptors (DP, EP1, EP2 …) based mainly on the pharmacological actions of natural and synthetic agonists and a few antagonists. The design of potent selective antagonists was rapid for certain prostanoid receptors (EP1, TP), slow for others (FP, IP) and has yet to be achieved in certain cases (EP2). While some antagonists are structurally related to the natural agonist, most recent compounds are ‘non-prostanoid’ (often acyl-sulphonamides) and have emerged from high-throughput screening of compound libraries, made possible by the development of (functional) assays involving single recombinant prostanoid receptors. Selective antagonists have been crucial to defining the roles of PGD2 (acting on DP1 and DP2 receptors) and PGE2 (on EP1 and EP4 receptors) in various inflammatory conditions; there are clear opportunities for therapeutic intervention. The vast endeavour on TP (thromboxane) antagonists is considered in relation to their limited pharmaceutical success in the cardiovascular area. Correspondingly, the clinical utility of IP (prostacyclin) antagonists is assessed in relation to the cloud hanging over the long-term safety of selective COX-2 inhibitors. Aspirin apart, COX inhibitors broadly suppress all prostanoid pathways, while high selectivity has been a major goal in receptor antagonist development; more targeted therapy may require an intermediate position with defined antagonist selectivity profiles. This review is intended to provide overviews of each antagonist class (including prostamide antagonists), covering major development strategies and current and potential clinical usage. PMID:19624532

  15. Gonadotropin-releasing hormone antagonist in in vitro fertilization superovulation.

    PubMed

    Seng, Shay Way; Ong, Kee Jiet; Ledger, W L

    2006-11-01

    The use of gonadotropin-releasing hormone (GnRH) antagonists in in vitro fertilization superovulation remains controversial. The GnRH agonist 'long protocol' has been seen as the gold standard for many years. Comparisons and meta-analyses of the efficacy of GnRH antagonists and agonists have been largely inconclusive, with the dataset being contaminated with outdated reports of poorer efficacy with GnRH antagonists, which have stemmed from studies of their use as a second-line drug in older women and women who were poor responders. This work cannot reflect the actual clinical effectiveness of GnRH antagonist and must be interpreted with care. The major advantages of GnRH antagonists use in superovulation include a gentler and more patient-friendly stimulation cycle with less hypoestrogenic side effects, with the potential to lower the risk of ovarian hyperstimulation and enhanced embryo growth. Our current clinical experience with GnRH antagonists in in vitro fertilization is limited, although there are a growing number of in vitro fertilization centers embracing this new technology. There is a clear need for a modern, suitably powered clinical trial to demonstrate the place of GnRH antagonist-based superovulation protocols and in subgroups of patients, such as polycystic ovary syndrome or poor responders.

  16. EGCG protects endothelial cells against PCB 126-induced inflammation through inhibition of AhR and induction of Nrf2-regulated genes

    SciTech Connect

    Han, Sung Gu; Department of Animal and Food Sciences, College of Agriculture, University of Kentucky, Lexington, KY 40536; Han, Seong-Su

    Tea flavonoids such as epigallocatechin gallate (EGCG) protect against vascular diseases such as atherosclerosis via their antioxidant and anti-inflammatory functions. Persistent and widespread environmental pollutants, including polychlorinated biphenyls (PCB), can induce oxidative stress and inflammation in vascular endothelial cells. Even though PCBs are no longer produced, they are still detected in human blood and tissues and thus considered a risk for vascular dysfunction. We hypothesized that EGCG can protect endothelial cells against PCB-induced cell damage via its antioxidant and anti-inflammatory properties. To test this hypothesis, primary vascular endothelial cells were pretreated with EGCG, followed by exposure to the coplanar PCBmore » 126. Exposure to PCB 126 significantly increased cytochrome P450 1A1 (Cyp1A1) mRNA and protein expression and superoxide production, events which were significantly attenuated following pretreatment with EGCG. Similarly, EGCG also reduced DNA binding of NF-κB and downstream expression of inflammatory markers such as monocyte chemotactic protein-1 (MCP-1) and vascular cell adhesion protein-1 (VCAM-1) after PCB exposure. Furthermore, EGCG decreased endogenous or base-line levels of Cyp1A1, MCP-1 and VCAM-1 in endothelial cells. Most of all, treatment of EGCG upregulated expression of NF-E2-related factor 2 (Nrf2)-controlled antioxidant genes, including glutathione S transferase (GST) and NAD(P)H:quinone oxidoreductase 1 (NQO1), in a dose-dependent manner. In contrast, silencing of Nrf2 increased Cyp1A1, MCP-1 and VCAM-1 and decreased GST and NQO1 expression, respectively. These data suggest that EGCG can inhibit AhR regulated genes and induce Nrf2-regulated antioxidant enzymes, thus providing protection against PCB-induced inflammatory responses in endothelial cells. -- Highlights: ► PCBs cause endothelial inflammation and subsequent atherosclerosis. ► Nutrition can modulate toxicity by environmental pollutants.

  17. Lipophilic components of diesel exhaust particles induce pro-inflammatory responses in human endothelial cells through AhR dependent pathway(s).

    PubMed

    Brinchmann, Bendik C; Skuland, Tonje; Rambøl, Mia H; Szoke, Krisztina; Brinchmann, Jan E; Gutleb, Arno C; Moschini, Elisa; Kubátová, Alena; Kukowski, Klara; Le Ferrec, Eric; Lagadic-Gossmann, Dominique; Schwarze, Per E; Låg, Marit; Refsnes, Magne; Øvrevik, Johan; Holme, Jørn A

    2018-05-11

    Exposure to traffic-derived particulate matter (PM), such as diesel exhaust particles (DEP), is a leading environmental cause of cardiovascular disease (CVD), and may contribute to endothelial dysfunction and development of atherosclerosis. It is still debated how DEP and other inhaled PM can contribute to CVD. However, organic chemicals (OC) adhered to the particle surface, are considered central to many of the biological effects. In the present study, we have explored the ability of OC from DEP to reach the endothelium and trigger pro-inflammatory reactions, a central step on the path to atherosclerosis. Exposure-relevant concentrations of DEP (0.12 μg/cm 2 ) applied on the epithelial side of an alveolar 3D tri-culture, rapidly induced pro-inflammatory and aryl hydrocarbon receptor (AhR)-regulated genes in the basolateral endothelial cells. These effects seem to be due to soluble lipophilic constituents rather than particle translocation. Extractable organic material of DEP (DEP-EOM) was next fractionated with increasing polarity, chemically characterized, and examined for direct effects on pro-inflammatory and AhR-regulated genes in human microvascular endothelial (HMEC-1) cells and primary human endothelial cells (PHEC) from four healthy donors. Exposure-relevant concentrations of lipophilic DEP-EOM (0.15 μg/cm 2 ) induced low to moderate increases in IL-1α, IL-1β, COX2 and MMP-1 gene expression, and the MMP-1 secretion was increased. By contrast, the more polar EOM had negligible effects, even at higher concentrations. Use of pharmacological inhibitors indicated that AhR and protease-activated receptor-2 (PAR-2) were central in regulation of EOM-induced gene expression. Some effects also seemed to be attributed to redox-responses, at least at the highest exposure concentrations tested. Although the most lipophilic EOM, that contained the majority of PAHs and aliphatics, had the clearest low-concentration effects, there was no straight-forward link

  18. Sexually antagonistic polymorphism in simultaneous hermaphrodites

    PubMed Central

    Jordan, Crispin Y.; Connallon, Tim

    2015-01-01

    In hermaphrodites, pleiotropic genetic tradeoffs between female and male reproductive functions can lead to sexually antagonistic (SA) selection, where individual alleles have conflicting fitness effects on each sex function. While an extensive theory of SA selection exists for dioecious species, these results have not been generalized to hermaphrodites. We develop population genetic models of SA selection in simultaneous hermaphrodites, and evaluate effects of dominance, selection on each sex function, self-fertilization, and population size, on the maintenance of polymorphism. Under obligate outcrossing, hermaphrodite model predictions converge exactly with those of dioecious populations. Self-fertilization in hermaphrodites generates three points of divergence with dioecious theory. First, opportunities for stable polymorphism decline sharply and become less sensitive to dominance with increased selfing. Second, selfing introduces an asymmetry in the relative importance of selection through male versus female reproductive functions, expands the parameter space favorable for the evolutionary invasion of female-beneficial alleles, and restricts invasion criteria for male-beneficial alleles. Finally, contrary to models of unconditionally beneficial alleles, selfing decreases genetic hitchhiking effects of invading SA alleles, and should therefore decrease these population genetic signals of SA polymorphisms. We discuss implications of SA selection in hermaphrodites, including its potential role in the evolution of “selfing syndromes”. PMID:25311368

  19. Adrenergic antagonists restrict replication of Legionella.

    PubMed

    Harrison, Christopher F; Kicka, Sébastien; Kranjc, Agata; Finsel, Ivo; Chiriano, Gianpaolo; Ouertatani-Sakouhi, Hajer; Soldati, Thierry; Scapozza, Leonardo; Hilbi, Hubert

    2015-07-01

    Legionella pneumophila is a facultative intracellular bacterium, which upon inhalation can cause a potentially fatal pneumonia termed Legionnaires' disease. The opportunistic pathogen grows in environmental amoebae and mammalian macrophages within a unique membrane-bound compartment, the 'Legionella-containing vacuole'. Bacteria are exposed to many environmental cues including small signalling molecules from eukaryotic cells. A number of pathogenic bacteria sense and respond to catecholamine hormones, such as adrenalin and noradrenalin, a process mediated via the QseBC two-component system in some bacteria. In this study, we examined the effect of adrenergic compounds on L. pneumophila, and discovered that the adrenergic receptor antagonists benoxathian, naftopidil, propranolol and labetalol, as well as the QseC sensor kinase inhibitor LED209, reduced the growth of L. pneumophila in broth or amoebae, while replication in macrophages was enhanced. Growth restriction was common to members of the genus Legionella and Mycobacterium, and was observed for L. pneumophila in the replicative but not stationary phase of the biphasic life cycle. Deletion of the L. pneumophila qseBC genes indicated that growth inhibition by adrenergics or LED209 is mediated only to a minor extent by this two-component system, implying the presence of other adrenergic sensing systems. This study identifies adrenergic molecules as novel inhibitors of extra- and intracellular growth of Legionella and reveals LED209 as a potential lead compound to combat infections with Legionella or Mycobacterium spp.

  20. Antagonistic neural networks underlying differentiated leadership roles.

    PubMed

    Boyatzis, Richard E; Rochford, Kylie; Jack, Anthony I

    2014-01-01

    The emergence of two distinct leadership roles, the task leader and the socio-emotional leader, has been documented in the leadership literature since the 1950s. Recent research in neuroscience suggests that the division between task-oriented and socio-emotional-oriented roles derives from a fundamental feature of our neurobiology: an antagonistic relationship between two large-scale cortical networks - the task-positive network (TPN) and the default mode network (DMN). Neural activity in TPN tends to inhibit activity in the DMN, and vice versa. The TPN is important for problem solving, focusing of attention, making decisions, and control of action. The DMN plays a central role in emotional self-awareness, social cognition, and ethical decision making. It is also strongly linked to creativity and openness to new ideas. Because activation of the TPN tends to suppress activity in the DMN, an over-emphasis on task-oriented leadership may prove deleterious to social and emotional aspects of leadership. Similarly, an overemphasis on the DMN would result in difficulty focusing attention, making decisions, and solving known problems. In this paper, we will review major streams of theory and research on leadership roles in the context of recent findings from neuroscience and psychology. We conclude by suggesting that emerging research challenges the assumption that role differentiation is both natural and necessary, in particular when openness to new ideas, people, emotions, and ethical concerns are important to success.

  1. Nonsteroidal mineralocorticoid antagonists in diabetic kidney disease.

    PubMed

    Dojki, Farheen K; Bakris, George

    2017-09-01

    Current data highlight the pathological aspects of excess aldosterone in promoting glomerular hypertrophy, glomerulosclerosis, and proteinuria in diabetic kidney disease (DKD). The role of nonsteroidal mineralocorticoid receptor antagonists (MRAs) in DKD is being evaluated in ongoing clinical trials. Recent studies demonstrate beneficial effects of adding MRAs to the treatment regimen of patients with type 2 diabetes with nephropathy. The MRAs spironolactone and eplerenone can protect against organ damage caused by elevated levels of serum aldosterone in patients with heart failure and DKD but are limited by their side effects, for example, hyperkalemia. Finerenone is more selective for the mineralocorticoid receptor than spironolactone and has greater affinity for the mineralocorticoid receptor than eplerenone. It reduces the concentration of aldosterone without causing significant elevation in serum potassium. MRAs have a clear role in reducing albuminuria when used with other renin-angiotensin system blockers in DKD; however, hyperkalemia limits their use. This article provides an overview of clinical studies with a novel MRA, finerenone, and several nonsteroidal MRAs being studied for treatment in DKD.

  2. Antagonistic neural networks underlying differentiated leadership roles

    PubMed Central

    Boyatzis, Richard E.; Rochford, Kylie; Jack, Anthony I.

    2014-01-01

    The emergence of two distinct leadership roles, the task leader and the socio-emotional leader, has been documented in the leadership literature since the 1950s. Recent research in neuroscience suggests that the division between task-oriented and socio-emotional-oriented roles derives from a fundamental feature of our neurobiology: an antagonistic relationship between two large-scale cortical networks – the task-positive network (TPN) and the default mode network (DMN). Neural activity in TPN tends to inhibit activity in the DMN, and vice versa. The TPN is important for problem solving, focusing of attention, making decisions, and control of action. The DMN plays a central role in emotional self-awareness, social cognition, and ethical decision making. It is also strongly linked to creativity and openness to new ideas. Because activation of the TPN tends to suppress activity in the DMN, an over-emphasis on task-oriented leadership may prove deleterious to social and emotional aspects of leadership. Similarly, an overemphasis on the DMN would result in difficulty focusing attention, making decisions, and solving known problems. In this paper, we will review major streams of theory and research on leadership roles in the context of recent findings from neuroscience and psychology. We conclude by suggesting that emerging research challenges the assumption that role differentiation is both natural and necessary, in particular when openness to new ideas, people, emotions, and ethical concerns are important to success. PMID:24624074

  3. Calcium channel antagonists in the treatment of hypertension.

    PubMed

    Weber, Michael A

    2002-01-01

    Calcium channel antagonists are widely used antihypertensive agents. Their popularity among primary care physicians is not only due to their blood pressure-lowering effects, but also because they appear to be effective regardless of the age or ethnic background of the patients. The first available calcium channel antagonists utilized immediate-release formulations which, although effective in patients with angina pectoris, were not approved by the US FDA for use in hypertension. When long-acting once-daily formulations were approved in this indication, the short-acting preparations--which had by then become generic and inexpensive--retained some residual unapproved use for hypertension. An observational case-controlled trial, based on such usage, noted that these agents were associated with a greater risk of myocardial infarctions than conventional agents such as diuretics and beta-adrenoceptor antagonists. Further case-controlled trials showed, in fact, that the dangers of calcium channel antagonists were confined to the short-acting agents and that approved long-acting agents were at least as well tolerated and effective as other antihypertensive drugs. Cardiovascular outcomes during treatment with calcium channel antagonists have been examined in randomized, controlled trials. Compared with placebo, the calcium channel antagonists clearly prevented strokes and other cardiovascular events and reduced mortality. The effects of these agents on survival and clinical outcomes were similar to those with other antihypertensive drugs. There is a slight tendency for the calcium channel antagonists to be more effective than other drug types in preventing stroke, but slightly less effective in preventing coronary events. These observations extend to high-risk patients with hypertension including those with diabetes mellitus. Even so, patients with evidence of nephropathy should not receive monotherapy with calcium channel antagonists. Such patients are optimally treated

  4. The muscarinic antagonists scopolamine and atropine are competitive antagonists at 5-HT3 receptors.

    PubMed

    Lochner, Martin; Thompson, Andrew J

    2016-09-01

    Scopolamine is a high affinity muscarinic antagonist that is used for the prevention of post-operative nausea and vomiting. 5-HT3 receptor antagonists are used for the same purpose and are structurally related to scopolamine. To examine whether 5-HT3 receptors are affected by scopolamine we examined the effects of this drug on the electrophysiological and ligand binding properties of 5-HT3A receptors expressed in Xenopus oocytes and HEK293 cells, respectively. 5-HT3 receptor-responses were reversibly inhibited by scopolamine with an IC50 of 2.09 μM. Competitive antagonism was shown by Schild plot (pA2 = 5.02) and by competition with the 5-HT3 receptor antagonists [(3)H]granisetron (Ki = 6.76 μM) and G-FL (Ki = 4.90 μM). The related molecule, atropine, similarly inhibited 5-HT evoked responses in oocytes with an IC50 of 1.74 μM, and competed with G-FL with a Ki of 7.94 μM. The reverse experiment revealed that granisetron also competitively bound to muscarinic receptors (Ki = 6.5 μM). In behavioural studies scopolamine is used to block muscarinic receptors and induce a cognitive deficit, and centrally administered concentrations can exceed the IC50 values found here. It is therefore possible that 5-HT3 receptors are also inhibited. Studies that utilise higher concentrations of scopolamine should be mindful of these potential off-target effects. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  5. Human muscle fascicle behavior in agonist and antagonist isometric contractions.

    PubMed

    Simoneau, Emilie M; Longo, Stefano; Seynnes, Olivier R; Narici, Marco V

    2012-01-01

    The aim of this study was to compare, at a given level of electromyographic (EMG) activity, the behavior of dorsiflexor and plantarflexor muscles as assessed via their architecture (pennation angle and fiber length) during agonist or antagonist isometric contractions. Real-time ultrasonography and EMG activity of gastrocnemius medialis (GM) and tibialis anterior (TA) muscles were obtained while young males performed ramp isometric contractions in dorsi- and plantarflexion. For both muscles, at a similar level of EMG activity, fiber length was longer, and pennation angle was smaller, during antagonist than during agonist contractions. These results indicate that, at similar levels of EMG activity, GM and TA muscles elicit a higher mechanical output while acting as an antagonist. These findings have important implications for muscle function testing. They show that estimation of antagonistic force using the common method based on the EMG/net torque relationship yields underestimated values. Copyright © 2011 Wiley Periodicals, Inc.

  6. Complications of TNF-α antagonists and iron homeostasis

    EPA Science Inventory

    TNF-α is a central regulator of inflammation and its blockade downregulates other proinflammatory cytokines, chemokines, and growth factors. Subsequently, TNF-α antagonists are currently used in treatment regimens directed toward several inflammatory diseases. Despite a beneficia...

  7. Alpha-adrenoceptor antagonistic and calcium antagonistic effects of nicergoline in the rat isolated aorta.

    PubMed

    Heitz, C; Descombes, J J; Miller, R C; Stoclet, J C

    1986-04-16

    The activity of the alpha-adrenoceptor antagonist nicergoline, a molecule composed of two constituent parts, ergoline and bromonicotinic acid, was investigated in the rat isolated aorta. Nicergoline (10 nM-0.1 microM) displaced concentration-effect curves elicited by noradrenaline and phenylephrine to the right and inhibited maximal responses elicited by both alpha-adrenoceptor agonists without significantly affecting prostaglandin F2 alpha-induced contractions. Higher concentrations of nicergoline (1 microM-50 microM) displaced to the right the concentration-effect curves elicited by calcium in a depolarizing medium. This calcium antagonist activity was not shared by either of the constituent parts. Nicergoline 100 microM abolished the 45Ca influx induced into rat aorta by 100 mM K+-containing physiological solution. The selectivity of nicergoline for alpha 1-adrenoceptors seen in binding experiments also depends on the presence of the bromonicotinic moiety of the molecule. It is concluded that nicergoline, but not its substituent parts, displays both alpha 1-adrenoceptor and calcium antagonism. The latter property may account for some of the observed effects of this compound.

  8. 5-HT7 Receptor Antagonists with an Unprecedented Selectivity Profile.

    PubMed

    Ates, Ali; Burssens, Pierre; Lorthioir, Olivier; Lo Brutto, Patrick; Dehon, Gwenael; Keyaerts, Jean; Coloretti, Francis; Lallemand, Bénédicte; Verbois, Valérie; Gillard, Michel; Vermeiren, Céline

    2018-04-23

    Selective leads: In this study, we generated a new series of serotonin 5-HT 7 receptor antagonists. Their synthesis, structure-activity relationships, and selectivity profiles are reported. This series includes 5-HT 7 antagonists with unprecedented high selectivity for the 5-HT 7 receptor, setting the stage for lead optimization of drugs acting on a range of neurological targets. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Identification of M-CSF agonists and antagonists

    DOEpatents

    Pandit, Jayvardhan [Mystic, CT; Jancarik, Jarmila [Walnut Creek, CA; Kim, Sung-Hou [Moraga, CA; Koths, Kirston [El Cerrito, CA; Halenbeck, Robert [San Rafael, CA; Fear, Anna Lisa [Oakland, CA; Taylor, Eric [Oakland, CA; Yamamoto, Ralph [Martinez, CA; Bohm, Andrew [Armonk, NY

    2000-02-15

    The present invention is directed to methods for crystallizing macrophage colony stimulating factor. The present invention is also directed to methods for designing and producing M-CSF agonists and antagonists using information derived from the crystallographic structure of M-CSF. The invention is also directed to methods for screening M-CSF agonists and antagonists. In addition, the present invention is directed to an isolated, purified, soluble and functional M-CSF receptor.

  10. Gonadotrophin-releasing hormone antagonists for assisted conception.

    PubMed

    Al-Inany, H G; Abou-Setta, A M; Aboulghar, M

    2006-07-19

    Gonadotrophin-releasing hormone antagonists produce immediate suppression of gonadotrophin secretion, hence, they can be given after starting gonadotrophin administration. This has resulted in dramatic reduction in the duration of treatment cycle. Two different regimes have been described. The multiple-dose protocol involves the administration of 0.25 mg cetrorelix (or ganirelix) daily from day six to seven of stimulation, or when the leading follicle is 14 to15 mm, until human chorionic gonadotrophin (HCG) administration and the single-dose protocol involves the single administration of 3 mg cetrorelix on day seven to eight of stimulation. Assuming comparable clinical outcome, these benefits would justify a change from the standard long protocol of GnRH agonists to the new GnRH antagonist regimens. To evaluate the evidence regarding the efficacy of gonadotrophin-releasing hormone (GnRH) antagonists with the standard long protocol of GnRH agonists for controlled ovarian hyperstimulation in assisted conception. We searched Cochrane Menstrual Disorders and Subfertility Group's Specialised Register, MEDLINE and EMBASE databases from 1987 to February 2006, and handsearched bibliographies of relevant publications and reviews, and abstracts of scientific meetings. We also contacted manufacturers in the field. Randomized controlled studies comparing different protocols of GnRH antagonists with GnRH agonists in assisted conception cycles were included in this review. Two authors independently assessed trial quality and extracted data. If relevant data were missing or unclear, the authors have been consulted Twenty seven RCTs comparing the GnRH antagonist to the long protocol of GnRH agonist fulfilled the inclusion criteria. Clinical pregnancy rate was significantly lower in the antagonist group. (OR = 0.84, 95% CI = 0.72 - 0.97). The ongoing pregnancy/ live-birth rate showed the same significant lower pregnancy in the antagonist group (P = 0.03; OR 0.82, 95% CI 0.69 to 0

  11. Vitamin K antagonist use and mortality in dialysis patients.

    PubMed

    Voskamp, Pauline W M; Rookmaaker, Maarten B; Verhaar, Marianne C; Dekker, Friedo W; Ocak, Gurbey

    2018-01-01

    The risk-benefit ratio of vitamin K antagonists for different CHA2DS2-VASc scores in patients with end-stage renal disease treated with dialysis is unknown. The aim of this study was to investigate the association between vitamin K antagonist use and mortality for different CHA2DS2-VASc scores in a cohort of end-stage renal disease patients receiving dialysis treatment. We prospectively followed 1718 incident dialysis patients. Hazard ratios were calculated for all-cause and cause-specific (stroke, bleeding, cardiovascular and other) mortality associated with vitamin K antagonist use. Vitamin K antagonist use as compared with no vitamin K antagonist use was associated with a 1.2-fold [95% confidence interval (95% CI) 1.0-1.5] increased all-cause mortality risk, a 1.5-fold (95% CI 0.6-4.0) increased stroke mortality risk, a 1.3-fold (95% CI 0.4-4.2) increased bleeding mortality risk, a 1.2-fold (95% CI 0.9-1.8) increased cardiovascular mortality risk and a 1.2-fold (95% CI 0.8-1.6) increased other mortality risk after adjustment. Within patients with a CHA2DS2-VASc score ≤1, vitamin K antagonist use was associated with a 2.8-fold (95% CI 1.0-7.8) increased all-cause mortality risk as compared with no vitamin K antagonist use, while vitamin K antagonist use within patients with a CHA2DS2-VASc score ≥2 was not associated with an increased mortality risk after adjustment. Vitamin K antagonist use was not associated with a protective effect on mortality in the different CHA2DS2-VASc scores in dialysis patients. The lack of knowledge on the indication for vitamin K antagonist use could lead to confounding by indication. © The Author 2017. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

  12. Antagonistic versus non-antagonistic models of balancing selection: Characterizing the relative timescales and hitchhiking effects of partial selective sweeps

    PubMed Central

    Connallon, Tim; Clark, Andrew G.

    2012-01-01

    Antagonistically selected alleles -- those with opposing fitness effects between sexes, environments, or fitness components -- represent an important component of additive genetic variance in fitness-related traits, with stably balanced polymorphisms often hypothesized to contribute to observed quantitative genetic variation. Balancing selection hypotheses imply that intermediate-frequency alleles disproportionately contribute to genetic variance of life history traits and fitness. Such alleles may also associate with population genetic footprints of recent selection, including reduced genetic diversity and inflated linkage disequilibrium at linked, neutral sites. Here, we compare the evolutionary dynamics of different balancing selection models, and characterize the evolutionary timescale and hitchhiking effects of partial selective sweeps generated under antagonistic versus non-antagonistic (e.g., overdominant and frequency-dependent selection) processes. We show that that the evolutionary timescales of partial sweeps tend to be much longer, and hitchhiking effects are drastically weaker, under scenarios of antagonistic selection. These results predict an interesting mismatch between molecular population genetic and quantitative genetic patterns of variation. Balanced, antagonistically selected alleles are expected to contribute more to additive genetic variance for fitness than alleles maintained by classic, non-antagonistic mechanisms. Nevertheless, classical mechanisms of balancing selection are much more likely to generate strong population genetic signatures of recent balancing selection. PMID:23461340

  13. Early Illustrations of Geste Antagoniste in Cervical and Generalized Dystonia

    PubMed Central

    Broussolle, Emmanuel; Laurencin, Chloé; Bernard, Emilien; Thobois, Stéphane; Danaila, Teodor; Krack, Paul

    2015-01-01

    Background Geste antagoniste, or sensory trick, is a voluntary maneuver that temporarily reduces the severity of dystonic postures or movements. We present a historical review of early reports and illustrations of geste antagoniste. Results In 1894, Brissaud described this phenomenon in Paris in patients with torticollis. He noted that a violent muscular contraction could be reversed by a minor voluntary action. He considered the improvement obtained by what he called “simple mannerisms, childish behaviour or fake pathological movements” was proof of the psychogenic origin of what he named mental torticollis. This concept was supported by photographical illustrations of the patients. The term geste antagoniste was used by Brissaud’s pupils, Meige and Feindel, in their 1902 monograph on movement disorders. Other reports and illustrations of this sign were published in Europe between 1894 and 1906. Although not mentioned explicitly, geste antagoniste was also illustrated in a case report of generalized dystonia in Oppenheim’s 1911 seminal description of dystonia musculorum deformans in Berlin. Discussion Brissaud-Meige’s misinterpretation of the geste antagoniste unfortunately anchored the psychogenic origin of dystonia for decades. In New York, Herz brought dystonia back into the realm of organic neurology in 1944. Thereafter, it was given prominence by other authors, notably Fahn and Marsden in the 1970–1980s. Nowadays, neurologists routinely investigate for geste antagoniste when a dystonic syndrome is suspected, because it provides a further argument in favor of dystonia. The term alleviating maneuver was proposed in 2014 to replace sensory trick or geste antagoniste. This major sign is now part of the motor phenomenology of the 2013 Movement Disorder Society’s classification of dystonia. PMID:26417535

  14. Combining NMR spectral and structural data to form models of polychlorinated dibenzodioxins, dibenzofurans, and biphenyls binding to the AhR

    NASA Astrophysics Data System (ADS)

    Beger, Richard D.; Buzatu, Dan A.; Wilkes, Jon G.

    2002-10-01

    A three-dimensional quantitative spectrometric data-activity relationship (3D-QSDAR) modeling technique which uses NMR spectral and structural information that is combined in a 3D-connectivity matrix has been developed. A 3D-connectivity matrix was built by displaying all possible assigned carbon NMR chemical shifts, carbon-to-carbon connections, and distances between the carbons. Two-dimensional 13C-13C COSY and 2D slices from the distance dimension of the 3D-connectivity matrix were used to produce a relationship among the 2D spectral patterns for polychlorinated dibenzofurans, dibenzodioxins, and biphenyls (PCDFs, PCDDs, and PCBs respectively) binding to the aryl hydrocarbon receptor (AhR). We refer to this technique as comparative structural connectivity spectral analysis (CoSCoSA) modeling. All CoSCoSA models were developed using forward multiple linear regression analysis of the predicted 13C NMR structure-connectivity spectral bins. A CoSCoSA model for 26 PCDFs had an explained variance (r2) of 0.93 and an average leave-four-out cross-validated variance (q4 2) of 0.89. A CoSCoSA model for 14 PCDDs produced an r2 of 0.90 and an average leave-two-out cross-validated variance (q2 2) of 0.79. One CoSCoSA model for 12 PCBs gave an r2 of 0.91 and an average q2 2 of 0.80. Another CoSCoSA model for all 52 compounds had an r2 of 0.85 and an average q4 2 of 0.52. Major benefits of CoSCoSA modeling include ease of development since the technique does not use molecular docking routines.

  15. Effects of an orally active vasopressin V1 receptor antagonist.

    PubMed

    Burrell, L M; Phillips, P A; Stephenson, J; Risvanis, J; Hutchins, A M; Johnston, C I

    1993-05-01

    1. This paper reports on the in vitro and in vivo characteristics of a non-peptide vasopressin V1 receptor antagonist 1-(1-[4-(3-acetylaminopropoxy)benzoyl]-4-piperidyl)-3,4-dihydro-2( 1H)- quinolinone (OPC-21268). 2. OPC-21268 caused a concentration-dependent displacement of the selective V1 receptor antagonist radioligand, [125I]-[d(CH2)5, sarcosine7]AVP from vasopressin V1 receptors in rat liver and kidney membranes, inhibitory concentration of 50% (IC50) 4 x 10(-8), 0.3 mol/L liver and 1.5 x 10(-8), 0.2 mol/L kidney. OPC-21268 had little effect on the selective V2 antagonist radioligand [3H]desGly-NH2(9)-d(CH2)5[D-Ileu2, Ileu4]AVP binding to V2 receptors in renal membranes (IC50 > 10(-4) mol/L). 3. After oral administration to rats, OPC-21268 was an effective V1 antagonist to both liver and kidney V1 receptors, in a dose-dependent manner. 4. These studies confirm that OPC-21268 is a potent non-peptide, orally effective V1 vasopressin receptor antagonist.

  16. Characterization of field isolates of Trichoderma antagonistic against Rhizoctonia solani.

    PubMed

    Anees, Muhammad; Tronsmo, Arne; Edel-Hermann, Véronique; Hjeljord, Linda Gordon; Héraud, Cécile; Steinberg, Christian

    2010-09-01

    The aim of the present study was to characterize sixteen isolates of Trichoderma originating from a field of sugar beet where disease patches caused by Rhizoctonia solani were observed. Use of both molecular and morphological characteristics gave consistent identification of the isolates. Production of water-soluble and volatile inhibitors, mycoparasitism and induced systemic resistance in plant host were investigated using in vitro and in vivo tests in both sterilized and natural soils. This functional approach revealed the intra-specific diversity as well as biocontrol potential of the different isolates. Different antagonistic mechanisms were evident for different strains. The most antagonistic strain, T30 was identified as Trichoderma gamsii. This is the first report of an efficient antagonistic strain of T. gamsii being able to reduce the disease in different conditions. The ability to produce water-soluble inhibitors or coil around the hyphae of the pathogen in vitro was not related to the disease reduction in vivo. Additionally, the strains collected from the high disease areas in the field were better antagonists. The antagonistic activity was not characteristic of a species but that of a population. Copyright © 2010 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  17. Neutralization of Staphylococcal Enterotoxin B by an Aptamer Antagonist

    PubMed Central

    Wang, Kaiyu; Gan, Longjie; Jiang, Li; Zhang, Xianhui; Yang, Xiangyue; Chen, Min

    2015-01-01

    Staphylococcal enterotoxin B (SEB) is a major virulence factor for staphylococcal toxic shock syndrome (TSS). SEB activates a large subset of the T lymphocytic population, releasing proinflammatory cytokines. Blocking SEB-initiated toxicity may be an effective strategy for treating TSS. Using a process known as systematic evolution of ligands by exponential enrichment (SELEX), we identified an aptamer that can antagonize SEB with nanomolar binding affinity (Kd = 64 nM). The aptamer antagonist effectively inhibits SEB-mediated proliferation and cytokine secretion in human peripheral blood mononuclear cells. Moreover, a PEGylated aptamer antagonist significantly reduced mortality in a “double-hit” mouse model of SEB-induced TSS, established via sensitization with d-galactosamine followed by SEB challenge. Therefore, our novel aptamer antagonist may offer potential therapeutic efficacy against SEB-mediated TSS. PMID:25624325

  18. Neuroprotective Effects of Glutamate Antagonists and Extracellular Acidity

    NASA Astrophysics Data System (ADS)

    Kaku, David A.; Giffard, Rona G.; Choi, Dennis W.

    1993-06-01

    Glutamate antagonists protect neurons from hypoxic injury both in vivo and in vitro, but in vitro studies have not been done under the acidic conditions typical of hypoxia-ischemia in vivo. Consistent with glutamate receptor antagonism, extracellular acidity reduced neuronal death in murine cortical cultures that were deprived of oxygen and glucose. Under these acid conditions, N-methyl-D-aspartate and α-amino-3-hydroxy-5-methyl-4-isox-azolepropionate-kainate antagonists further reduced neuronal death, such that some neurons tolerated prolonged oxygen and glucose deprivation almost as well as did astrocytes. Neuroprotection induced by this combination exceeded that induced by glutamate antagonists alone, suggesting that extracellular acidity has beneficial effects beyond the attenuation of ionotropic glutamate receptor activation.

  19. Cancer in patients with rheumatic diseases exposed to TNF antagonists.

    PubMed

    Carmona, Loreto; Abasolo, Lydia; Descalzo, Miguel A; Pérez-Zafrilla, Beatriz; Sellas, Agustí; de Abajo, Francisco; Gomez-Reino, Juan J

    2011-08-01

    To describe the risk of cancer in patients exposed to tumor necrosis factor (TNF) antagonists. The following 2 clinical cohorts were studied: (1) BIOBADASER 2.0: a registry of patients suffering from rheumatic diseases exposed to TNF antagonists (2531 rheumatoid arthritis (RA), 1488 spondyloarthropathies, and 675 other rheumatic conditions); and (2) EMECAR: a cohort of 789 RA patients not exposed to TNF antagonists. Cancer incidence rates (IR) per 1000 patient-years and incidence rate ratios (IRR) were calculated for BIOBADASER 2.0 and EMECAR patients. The IR over time in BIOBADASER 2.0 patients was analyzed by joinpoint regression. The IRR was estimated to compare cancer rates in exposed versus nonexposed RA patients. Standardized incidence and mortality ratios (SIR, SMR) were also estimated. Risk factors for cancer in patients exposed to TNF antagonists were investigated by generalized linear models. The SMR for cancer in BIODASER 2.0 was 0.67 (95% CI: 0.51-0.86), and the SIR was 0.1 (95% CI 0.03-0.23). The IR in RA patients exposed to TNF antagonists was 5.8 (95% CI: 4.4-7.6), and the adjusted IRR was 0.48 (95% CI: 0.09-2.45). The IR in patients with previous cancer was 26.4 (95% CI: 4.1-171.5). Age, chronic obstructive pulmonary disease, and steroids were associated with a higher risk of developing cancer. The IR decreased after the first 4 months of exposure, without statistical significance. Overall cancer and mortality rates in patients with rheumatic diseases exposed to TNF antagonists are no higher than in the background Spanish population. However special attention should be paid to elderly patients, those with previous cancers, and patients treated with steroids. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Progesterone receptor isoforms, agonists and antagonists differentially reprogram estrogen signaling

    PubMed Central

    Singhal, Hari; Greene, Marianne E.; Zarnke, Allison L.; Laine, Muriel; Al Abosy, Rose; Chang, Ya-Fang; Dembo, Anna G.; Schoenfelt, Kelly; Vadhi, Raga; Qiu, Xintao; Rao, Prakash; Santhamma, Bindu; Nair, Hareesh B.; Nickisch, Klaus J.; Long, Henry W.; Becker, Lev; Brown, Myles; Greene, Geoffrey L.

    2018-01-01

    Major roadblocks to developing effective progesterone receptor (PR)-targeted therapies in breast cancer include the lack of highly-specific PR modulators, a poor understanding of the pro- or anti-tumorigenic networks for PR isoforms and ligands, and an incomplete understanding of the cross talk between PR and estrogen receptor (ER) signaling. Through genomic analyses of xenografts treated with various clinically-relevant ER and PR-targeting drugs, we describe how the activation or inhibition of PR differentially reprograms estrogen signaling, resulting in the segregation of transcriptomes into separate PR agonist and antagonist-mediated groups. These findings address an ongoing controversy regarding the clinical utility of PR agonists and antagonists, alone or in combination with tamoxifen, for breast cancer management. Additionally, the two PR isoforms PRA and PRB, bind distinct but overlapping genomic sites and interact with different sets of co-regulators to differentially modulate estrogen signaling to be either pro- or anti-tumorigenic. Of the two isoforms, PRA inhibited gene expression and ER chromatin binding significantly more than PRB. Differential gene expression was observed in PRA and PRB-rich patient tumors and PRA-rich gene signatures had poorer survival outcomes. In support of antiprogestin responsiveness of PRA-rich tumors, gene signatures associated with PR antagonists, but not PR agonists, predicted better survival outcomes. The better patient survival associated with PR antagonists versus PR agonists treatments was further reflected in the higher in vivo anti-tumor activity of therapies that combine tamoxifen with PR antagonists and modulators. This study suggests that distinguishing common effects observed due to concomitant interaction of another receptor with its ligand (agonist or antagonist), from unique isoform and ligand-specific effects will inform the development of biomarkers for patient selection and translation of PR

  1. Discovery of tertiary sulfonamides as potent liver X receptor antagonists.

    PubMed

    Zuercher, William J; Buckholz, Richard G; Campobasso, Nino; Collins, Jon L; Galardi, Cristin M; Gampe, Robert T; Hyatt, Stephen M; Merrihew, Susan L; Moore, John T; Oplinger, Jeffrey A; Reid, Paul R; Spearing, Paul K; Stanley, Thomas B; Stewart, Eugene L; Willson, Timothy M

    2010-04-22

    Tertiary sulfonamides were identified in a HTS as dual liver X receptor (LXR, NR1H2, and NR1H3) ligands, and the binding affinity of the series was increased through iterative analogue synthesis. A ligand-bound cocrystal structure was determined which elucidated key interactions for high binding affinity. Further characterization of the tertiary sulfonamide series led to the identification of high affinity LXR antagonists. GSK2033 (17) is the first potent cell-active LXR antagonist described to date. 17 may be a useful chemical probe to explore the cell biology of this orphan nuclear receptor.

  2. Hyperglycemia of Diabetic Rats Decreased by a Glucagon Receptor Antagonist

    NASA Astrophysics Data System (ADS)

    Johnson, David G.; Ulichny Goebel, Camy; Hruby, Victor J.; Bregman, Marvin D.; Trivedi, Dev

    1982-02-01

    The glucagon analog [l-Nα-trinitrophenylhistidine, 12-homoarginine]-glucagon (THG) was examined for its ability to lower blood glucose concentrations in rats made diabetic with streptozotocin. In vitro, THG is a potent antagonist of glucagon activation of the hepatic adenylate cyclase assay system. Intravenous bolus injections of THG caused rapid decreases (20 to 35 percent) of short duration in blood glucose. Continuous infusion of low concentrations of the inhibitor led to larger sustained decreases in blood glucose (30 to 65 percent). These studies demonstrate that a glucagon receptor antagonist can substantially reduce blood glucose levels in diabetic animals without addition of exogenous insulin.

  3. Discovery of Tertiary Sulfonamides as Potent Liver X Receptor Antagonists

    SciTech Connect

    Zuercher, William J.; Buckholz†, Richard G.; Campobasso, Nino

    2010-08-12

    Tertiary sulfonamides were identified in a HTS as dual liver X receptor (LXR, NR1H2, and NR1H3) ligands, and the binding affinity of the series was increased through iterative analogue synthesis. A ligand-bound cocrystal structure was determined which elucidated key interactions for high binding affinity. Further characterization of the tertiary sulfonamide series led to the identification of high affinity LXR antagonists. GSK2033 (17) is the first potent cell-active LXR antagonist described to date. 17 may be a useful chemical probe to explore the cell biology of this orphan nuclear receptor.

  4. Bone Morphogenetic Proteins, Antagonists and Receptors in Prostate Cancer

    DTIC Science & Technology

    2005-01-01

    expressed in prostate. This work investigates BMP receptors and BMP antagonists to understand the basic mechanisms to inhibit the BMP signaling in...during embryoge- nesis, and prostate cancer metastases to bone. BMP functions can be inhibited by antagonists such as Noggin or DAN. DAN is a protein...protein along with a constant 0-6 -1 10 100 1000 1O0ng/ml of BMP-6, we were able to show a ng/ml BMP-6 dose-dependent inhibition of BMP-6 activity in DU

  5. Attenuation in rats of impairments of memory by scopolamine, a muscarinic receptor antagonist, by mecamylamine, a nicotinic receptor antagonist.

    PubMed

    Newman, L A; Gold, P E

    2016-03-01

    Scopolamine, a muscarinic antagonist, impairs learning and memory for many tasks, supporting an important role for the cholinergic system in these cognitive functions. The findings are most often interpreted to indicate that a decrease in postsynaptic muscarinic receptor activation mediates the memory impairments. However, scopolamine also results in increased release of acetylcholine in the brain as a result of blocking presynaptic muscarinic receptors. The present experiments assess whether scopolamine-induced increases in acetylcholine release may impair memory by overstimulating postsynaptic cholinergic nicotinic receptors, i.e., by reaching the high end of a nicotinic receptor activation inverted-U dose-response function. Rats tested in a spontaneous alternation task showed dose-dependent working memory deficits with systemic injections of mecamylamine and scopolamine. When an amnestic dose of scopolamine (0.15 mg/kg) was co-administered with a subamnestic dose of mecamylamine (0.25 mg/kg), this dose of mecamylamine significantly attenuated the scopolamine-induced memory impairments. We next assessed the levels of acetylcholine release in the hippocampus in the presence of scopolamine and mecamylamine. Mecamylamine injections resulted in decreased release of acetylcholine, while scopolamine administration caused a large increase in acetylcholine release. These findings indicate that a nicotinic antagonist can attenuate impairments in memory produced by a muscarinic antagonist. The nicotinic antagonist may block excessive activation of nicotinic receptors postsynaptically or attenuate increases in acetylcholine release presynaptically. Either effect of a nicotinic antagonist-to decrease scopolamine-induced increases in acetylcholine output or to decrease postsynaptic acetylcholine receptor activation-may mediate the negative effects on memory of muscarinic antagonists.

  6. The chlorinated AHR ligand 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) promotes reactive oxygen species (ROS) production during embryonic development in the killifish (Fundulus heteroclitus)

    USGS Publications Warehouse

    Arzuaga, Xabier; Wassenberg, Deena; Giulio, Richard D.; Elskus, Adria

    2006-01-01

    Exposure to dioxin-like chemicals that activate the aryl hydrocarbon receptor (AHR) can result in increased cellular and tissue production of reactive oxygen species (ROS). Little is known of these effects during early fish development. We used the fish model, Fundulus heteroclitus, to determine if the AHR ligand and pro-oxidant 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) can increase ROS production during killifish development, and to test a novel method for measuring ROS non-invasively in a living organism. The superoxide-sensitive fluorescent dye, dihydroethidium (DHE), was used to detect in ovo ROS production microscopically in developing killifish exposed to PCB126 or vehicle. Both in ovo CYP1A activity (ethoxyresorufin-o-deethylase, EROD) and in ovo ROS were induced by PCB126. In ovo CYP1A activity was inducible by PCB126 concentrations as low as 0.003 nM, with maximal induction occurring at 0.3 nM PCB126. These PCB126 concentrations also significantly increased in ovo ROS production in embryonic liver, ROS being detectable as early as 5 days post-fertilization. These data demonstrate that the pro-oxidant and CYP1A inducer, PCB126, increases both CYP1A activity and ROS production in developing killifish embryos. The superoxide detection assay (SoDA) described in this paper provides a semi-quantitative, easily measured, early indicator of altered ROS production that can be used in conjunction with simultaneous in ovo measurements of CYP1A activity and embryo development to explore functional relationships among biochemical, physiological and developmental responses to AHR ligands.

  7. Enhanced Chronic Pain Management Utilizing Chemokine Receptor Antagonists

    DTIC Science & Technology

    2016-08-01

    approximately halfway into the solution. All animals were tested at 60, 15 and 0 min before drug injection. For each animal , the first reading was discarded...approval (December 31, 2015), hiring new personnel, conducting baseline testing for procedures not involving animals , testing equipment, developing...treatment; Analgesia; Nociception; Antinociception; Inflammation; Chemokines; Chemokine receptor antagonists; Opioid analgesics; Animal models of pain

  8. TRPV1 Antagonists and Chronic Pain: Beyond Thermal Perception

    PubMed Central

    Brandt, Michael R.; Beyer, Chad E.; Stahl, Stephen M.

    2012-01-01

    In the last decade, considerable evidence as accumulated to support the development of Transient Receptor Potential Vanilloid 1 (TRPV1) antagonists for the treatment of various chronic pain conditions. Whereas there is a widely accepted rationale for the development of TRPV1 antagonists for the treatment of various inflammatory pain conditions, their development for indications of chronic pain, where conditions of tactical, mechanical and spontaneous pain predominate, is less clear. Preclinical localization and expression studies provide a firm foundation for the use of molecules targeting TRPV1 for conditions of bone pain, osteoarthritis and neuropathic pain. Selective TRPV1 antagonists weakly attenuate tactile and mechanical hypersensivity and are partially effective for behavioral and electrophysiological endpoints that incorporate aspects of spontaneous pain. While initial studies with TRPV1 antagonist in normal human subjects indicate a loss of warm thermal perception, clinical studies assessing allelic variants suggests that TRPV1 may mediate other sensory modalities under certain conditions. The focus of this review is to summarize the current perspectives of TRPV1 for the treatment of conditions beyond those with a primary thermal sensitivity. PMID:24288084

  9. Ankle dynamic in stroke patients: agonist vs. antagonist muscle relations.

    PubMed

    Silva, Augusta; Sousa, Andreia S P; Tavares, João Manuel R S; Tinoco, Ana; Santos, Rubim; Sousa, Filipa

    2012-01-01

    Atypical ankle patterns of muscle activity during gait are commonly reported in patients with stroke. These findings can be due to changes between tibialis anterior (TA) and soleus (SOL) coactivation mechanisms. To compare the electromyographic activity (EMGa) of SOL and TA muscles and antagonist coactivation (C) level in the contralateral (CONTRA) and ipsilateral (IPSI) limbs to the side of the stroke lesion during the stance phase of the gait cycle. Twelve subjects with a stroke episode participated in this study. The electromyographic signal of TA and SOL and ground reaction forces were acquired while subjects walked at their self-selected speed. Values of ground reaction forces were used to divide the stance phase of gait into initial contact, midstance, and terminal stance. In each sub-phase, the magnitude of TA and SOL was calculated as well as the level of the antagonist C. Although no statistical differences were found, mean values of SOL EMGa were lower in the IPSI limb in all stance phases in relation to the CONTRA limb, and the opposite was observed in the TA EMGa. Moreover, higher mean levels of antagonist C were only found during the initial contact sub-phase in the CONTRA limb and in the other sub-phases in the IPSI limb. Besides, statistical differences were observed only during midstance. In stroke subjects, the antagonist C level during midstance of gait may reflect the dysfunction of the neuronal system over the IPSI limb.

  10. Non-NMDA receptor antagonist-induced drinking in rat

    NASA Technical Reports Server (NTRS)

    Xu, Z.; Johnson, A. K.

    1998-01-01

    Glutamate has been implicated in the central control of mechanisms that maintain body fluid homeostasis. The present studies demonstrate that intracerebroventricular (i.c.v.) injections of the non-N-methyl-d-aspartate (NMDA) receptor antagonists 6, 7-dinitroquinoxaline-2,3-dione (DNQX) and 6-cyano-7-nitroquinoxaline-2,3 dione (CNQX) induce drinking in rats. The dipsogenic effect of i.c.v. DNQX was antagonized by the non-NMDA receptor agonist alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA). The water intake induced by DNQX was also blocked by pretreatment with a NMDA receptor antagonist, MK-801, but not by angiotensin type 1 (AT1) or acetylcholine muscarinic receptor antagonists (losartan and atropine). The results indicate that non-NMDA receptors may exert a tonic inhibitory effect within brain circuits that control dipsogenic activity and that functional integrity of NMDA receptors may be required for the non-NMDA receptor antagonists to induce water intake. Copyright 1998 Published by Elsevier Science B.V.

  11. Antagonistic actuation and stiffness control in soft inflatable robots

    NASA Astrophysics Data System (ADS)

    Althoefer, Kaspar

    2018-06-01

    Soft robots promise solutions for a wide range of applications that cannot be achieved with traditional, rigid-component robots. A key challenge is the creation of robotic structures that can vary their stiffness at will, for example, by using antagonistic actuators, to optimize their interaction with the environment and be able to exert high forces.

  12. Medium-Induced Antagonistic Behavior in Staphylococcus Aureus.

    ERIC Educational Resources Information Center

    Benathen, Isaiah A.

    1992-01-01

    Antagonism is the production of substances by microorganisms that inhibit or prevent the growth of other bacteria. This paper demonstrates the antagonistic behavior of gram-positive coccus on the B. subtilis and Enterococcus faecalis gram-positive microorganisms, showing that the process of antagonism is sometimes dependent on the nutritional…

  13. An Antagonistic Dialogue about Chaordic Systems Thinking: Part I

    ERIC Educational Resources Information Center

    Wafler, Toni

    2004-01-01

    This paper explores the added value of chaordic systems Thinking for organizational renewal, which is defined as transformation instead of reformation. The exploration is presented in the form of an antagonistic dialogue between two "voices," which develop commentaries from distinct theoretical inspirations, namely chaordic systems thinking (CST)…

  14. Orexin OX2 Receptor Antagonists as Sleep Aids.

    PubMed

    Jacobson, Laura H; Chen, Sui; Mir, Sanjida; Hoyer, Daniel

    The discovery of the orexin system represents the single major progress in the sleep field of the last three to four decades. The two orexin peptides and their two receptors play a major role in arousal and sleep/wake cycles. Defects in the orexin system lead to narcolepsy with cataplexy in humans and dogs and can be experimentally reproduced in rodents. At least six orexin receptor antagonists have reached Phase II or Phase III clinical trials in insomnia, five of which are dual orexin receptor antagonists (DORAs) that target both OX 1 and OX 2 receptors (OX 2 Rs). All clinically tested DORAs induce and maintain sleep: suvorexant, recently registered in the USA and Japan for insomnia, represents the first hypnotic principle that acts in a completely different manner from the current standard medications. It is clear, however, that in the clinic, all DORAs promote sleep primarily by increasing rapid eye movement (REM) and are almost devoid of effects on slow-wave (SWS) sleep. At present, there is no consensus on whether the sole promotion of REM sleep has a negative impact in patients suffering from insomnia. However, sleep onset REM (SOREM), which has been documented with DORAs, is clearly an undesirable effect, especially for narcoleptic patients and also in fragile populations (e.g. elderly patients) where REM-associated loss of muscle tone may promote an elevated risk of falls. Debate thus remains as to the ideal orexin agent to achieve a balanced increase in REM and non-rapid eye movement (NREM) sleep. Here, we review the evidence that an OX 2 R antagonist should be at least equivalent, or perhaps superior, to a DORA for the treatment of insomnia. An OX 2 R antagonist may produce more balanced sleep than a DORA. Rodent sleep experiments show that the OX 2 R is the primary target of orexin receptor antagonists in sleep modulation. Furthermore, an OX 2 R antagonist should, in theory, have a lower narcoleptic/cataplexic potential. In the clinic, the situation

  15. Vasopressin and a nonpeptide antidiuretic hormone receptor antagonist (OPC-31260).

    PubMed

    Burrell, L M; Phillips, P A; Stephenson, J M; Risvanis, J; Johnston, C I

    1994-03-01

    The development of nonpeptide orally active AVP analogues has provided a new tool with which to assess the physiological and pathophysiological role of vasopressin (AVP). We have previously characterised the nonpeptide vasopressin V1 receptor antagonist OPC-21268, and now report the in vitro characterisation of the nonpeptide V2 receptor antagonist OPC-31260 in the rat. OPC-31260 caused a concentration-dependent displacement of the selective AVP V2 receptor antagonist radioligand, [3H]desGly-NH2(9)[d(CH2)5, D-Ile2,Ile4]AVP from V2 receptors in rat kidney medulla membranes. The concentration of OPC-31260 that displaced 50% of specific AVP binding (IC50) was 20 +/- 2 nmol/l for renal V2 receptors. OPC-31260 also caused a concentration-dependent displacement of the selective AVP V1 receptor antagonist radioligand, [125I]-[d(CH2)5,sarcosine7]AVP from V1 receptors in both rat liver and kidney medulla membranes. The IC50 was 500 +/- 30 nmol/l for both renal and liver V1 receptors. After oral administration to rats, OPC-31260 was an effective inhibitor of AVP at renal V2 and liver V1 receptors in a time-dependent manner. In vitro binding kinetic studies showed that OPC-31260 was a competitive antagonist at both the renal V2 receptor and the hepatic V1 receptor. OPC-31260 is a nonpeptide, orally effective competitive inhibitor of AVP with a V2:V1 receptor selectivity ratio of 25:1 indicating relative V2 receptor selectivity.

  16. Novel long‐acting antagonists of muscarinic ACh receptors

    PubMed Central

    Randáková, Alena; Rudajev, Vladimír; Doležal, Vladimír; Boulos, John

    2018-01-01

    Background and Purpose The aim of this study was to develop potent and long‐acting antagonists of muscarinic ACh receptors. The 4‐hexyloxy and 4‐butyloxy derivatives of 1‐[2‐(4‐oxidobenzoyloxy)ethyl]‐1,2,3,6‐tetrahydropyridin‐1‐ium were synthesized and tested for biological activity. Antagonists with long‐residence time at receptors are therapeutic targets for the treatment of several neurological and psychiatric human diseases. Their long‐acting effects allow for reduced daily doses and adverse effects. Experimental Approach The binding and antagonism of functional responses to the agonist carbachol mediated by 4‐hexyloxy compounds were investigated in CHO cells expressing individual subtypes of muscarinic receptors and compared with 4‐butyloxy analogues. Key Results The 4‐hexyloxy derivatives were found to bind muscarinic receptors with micromolar affinity and antagonized the functional response to carbachol with a potency ranging from 30 nM at M1 to 4 μM at M3 receptors. Under washing conditions to reverse antagonism, the half‐life of their antagonistic action ranged from 1.7 h at M2 to 5 h at M5 receptors. Conclusions and Implications The 4‐hexyloxy derivatives were found to be potent long‐acting M1‐preferring antagonists. In view of current literature, M1‐selective antagonists may have therapeutic potential for striatal cholinergic dystonia, delaying epileptic seizure after organophosphate intoxication or relieving depression. These compounds may also serve as a tool for research into cognitive deficits. PMID:29498041

  17. Antagonistic interactions between plant competition and insect herbivory.

    PubMed

    Schädler, Martin; Brandl, Roland; Haase, Josephine

    2007-06-01

    Interspecific competition between plants and herbivory by specialized insects can have synergistic effects on the growth and performance of the attacked host plant. We tested the hypothesis that competition between plants may also negatively affect the performance of herbivores as well as their top-down effect on the host plant. In such a case, the combined effects of competition and herbivory may be less than expected from a simple multiplicative response. In other words, competition and herbivory may interact antagonistically. In a greenhouse experiment, Poa annua was grown in the presence or absence of a competitor (either Plantago lanceolata or Trifolium repens), as well as with or without a Poa-specialist aphid herbivore. Both competition and herbivory negatively affected Poa growth. Competition also reduced aphid density on Poa. This effect could in part be explained by changes in the biomass and the nitrogen content of Poa shoots. In treatments with competitors, reduced aphid densities alleviated the negative effect of herbivory on above- and belowground Poa biomass. Hence, we were able to demonstrate an antagonistic interaction between plant-plant interspecific competition and herbivory. However, response indices suggested that antagonistic interactions between competition and herbivory were contingent on the identity of the competitor. We found the antagonistic effect only in treatments with T. repens as the competitor. We conclude that both competitor identity and the herbivore's ability to respond with changes in its density or activity to plant competition affect the magnitude and direction (synergistic vs. antagonistic) of the interaction between competition and herbivory on plant growth.

  18. Attenuation in rats of impairments of memory by scopolamine, a muscarinic receptor antagonist, by mecamylamine, a nicotinic receptor antagonist

    PubMed Central

    Newman, L. A.

    2015-01-01

    Rationale Scopolamine, a muscarinic antagonist, impairs learning and memory for many tasks, supporting an important role for the cholinergic system in these cognitive functions. The findings are most often interpreted to indicate that a decrease in postsynaptic muscarinic receptor activation mediates the memory impairments. However, scopolamine also results in increased release of acetylcholine in the brain as a result of blocking presynaptic muscarinic receptors. Objectives The present experiments assess whether scopolamine-induced increases in acetylcholine release may impair memory by overstimulating postsynaptic cholinergic nicotinic receptors, i.e., by reaching the high end of a nicotinic receptor activation inverted-U dose-response function. Results Rats tested in a spontaneous alternation task showed dose-dependent working memory deficits with systemic injections of mecamylamine and scopolamine. When an amnestic dose of scopolamine (0.15 mg/kg) was co-administered with a subamnestic dose of mecamylamine (0.25 mg/kg), this dose of mecamylamine significantly attenuated the scopolamine-induced memory impairments. We next assessed the levels of acetylcholine release in the hippocampus in the presence of scopolamine and mecamylamine. Mecamylamine injections resulted in decreased release of acetylcholine, while scopolamine administration caused a large increase in acetylcholine release. Conclusions These findings indicate that a nicotinic antagonist can attenuate impairments in memory produced by a muscarinic antagonist. The nicotinic antagonist may block excessive activation of nicotinic receptors postsynaptically or attenuate increases in acetylcholine release presynaptically. Either effect of a nicotinic antagonist—to decrease scopolamine-induced increases in acetylcholine output or to decrease post-synaptic acetylcholine receptor activation—may mediate the negative effects on memory of muscarinic antagonists. PMID:26660295

  19. Competitive antagonists discriminate between NK2 tachykinin receptor subtypes.

    PubMed

    Maggi, C A; Patacchini, R; Giuliani, S; Rovero, P; Dion, S; Regoli, D; Giachetti, A; Meli, A

    1990-07-01

    1. We have compared the ability of various tachykinins and selective tachykinin receptor agonists to induce contraction of the endothelium-denuded rabbit pulmonary artery (RPA) and hamster trachea (HT) and have estimated the affinity of some newly developed NK2 selective antagonists in the same tissues. 2. In confirmation of previous findings, experiments with the agonists indicated that NK2 receptors are the main if not the sole mediators of the response to tachykinins in both RPA and HT. No evidence for significant degradation of neurokinin A (NKA) was found in either tissue when experiments were repeated in the presence of a mixture of peptidase inhibitors (thiorphan, captopril and bestatin, 1 microM each). 3. The peptide antagonists tested were: Peptide I = [Tyr5, D-Trp6,8,9, Arg10]-NKA(4-10); Peptide II = [Tyr5, D-Trp6,8,9, Arg10]-NKA(3-10); Peptide III = Ac-Leu-Asp-Gln-Trp-Phe-Gly-NH2. The three peptides produced a concentration-dependent rightward shift of the concentration-response curve to NKA in both RPA and HT with no significant depression of the maximal response attainable. The slopes of the Schild plots were not significantly different from unity, indicating a competitive antagonism. Peptides I and II were about 100 times more potent in the RPA than in the HT, while Peptide III was about 100 times more potent in the HT than RPA. 4. The pA2 values obtained in these two tissues with the three antagonists were not significantly different when tested in the absence or presence of peptidase inhibitors, or when a selective NK2 receptor agonist, [beta Ala8]-NKA(4-10) was used instead of NKA. Similar pA2 values were obtained after 15 or 90min of incubation with the antagonists. Peptides I, II and III had no inhibitory effect on contractions produced by noradrenaline in the RPA or by carbachol in the HT. 5. Peptides I, II and III showed weak or no antagonistic activity toward the vasodilatator effect of substance P in the dog carotid artery (NK, receptor

  20. Kinin B1 receptor antagonists containing alpha-methyl-L-phenylalanine: in vitro and in vivo antagonistic activities.

    PubMed

    Gobeil, F; Charland, S; Filteau, C; Perron, S I; Neugebauer, W; Regoli, D

    1999-03-01

    -To protect from metabolism and to improve potency of the AcLys-[D-betaNal7,Ile8]desArg9-bradykinin (BK) (R 715), we prepared and tested 3 analogues containing alpha-methyl-L-Phe ([alphaMe]Phe) in position 5: these are the AcLys-[(alphaMe)Phe5,D-betaNal7, Ile8]desArg9BK (R 892), Lys-Lys-[(alphaMe)Phe5,D-betaNal7, Ile8]desArg9BK (R 913), and AcLys-Lys-[(alphaMe)Phe5,D-betaNal7, Ile8]desArg9BK (R 914). The new compounds were tested against the contractile effect induced by desArg9BK on 2 B1 receptor bioassays, the human umbilical vein, and the rabbit aorta. Their antagonistic activities were compared with those of the early prototypes (Lys-[Leu8]desArg9BK and [Leu8]desArg9BK) and with other recently described peptide antagonists. The 3 (alphaMe)Phe analogues showed high antagonistic potencies (pA2) at both the human (8.8, 7.7, and 8. 7, respectively) and rabbit (8.6, 7.8, and 8.6, respectively) B1 receptors. No antagonistic effects (pA2<5) were observed on the B2 receptors that mediate the contractile effects of BK on the human umbilical vein, the rabbit jugular vein, and the guinea pig ileum. Moreover, these new B1 antagonists were found to be resistant to in vitro degradation by purified angiotensin-converting enzyme from rabbit lung. The Nalpha-acetylated forms, R 892 and R 914, were resistant to aminopeptidases from human plasma. In vivo antagonistic potencies (ID50) of B1 receptor antagonists were evaluated in anesthetized lipopolysaccharide-treated (for B1 receptor) and nontreated (for B2 receptor) rabbits against the hypotensive effects of exogenous desArg9BK and BK. R 892 efficiently inhibited (ID50 2.8 nmol/kg IV) hypotension induced by desArg9BK without affecting that evoked by BK (ID50 >600 nmol/kg IV). Conversely, the peptide antagonists Lys-Lys-[Hyp3,Igl5,D-Igl7,Oic8]desArg9BK (B 9858) and DArg-[Hyp3,Thi5,D-Tic7,Oic8] desArg9BK (S 0765) showed dual B1/B2 receptor antagonism in vitro and in vivo. It is concluded that R 892 and congeners provide selective

  1. In-silico guided discovery of novel CCR9 antagonists

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Cross, Jason B.; Romero, Jan; Heifetz, Alexander; Humphries, Eric; Hall, Katie; Wu, Yuchuan; Stucka, Sabrina; Zhang, Jing; Chandonnet, Haoqun; Lippa, Blaise; Ryan, M. Dominic; Baber, J. Christian

    2018-03-01

    Antagonism of CCR9 is a promising mechanism for treatment of inflammatory bowel disease, including ulcerative colitis and Crohn's disease. There is limited experimental data on CCR9 and its ligands, complicating efforts to identify new small molecule antagonists. We present here results of a successful virtual screening and rational hit-to-lead campaign that led to the discovery and initial optimization of novel CCR9 antagonists. This work uses a novel data fusion strategy to integrate the output of multiple computational tools, such as 2D similarity search, shape similarity, pharmacophore searching, and molecular docking, as well as the identification and incorporation of privileged chemokine fragments. The application of various ranking strategies, which combined consensus and parallel selection methods to achieve a balance of enrichment and novelty, resulted in 198 virtual screening hits in total, with an overall hit rate of 18%. Several hits were developed into early leads through targeted synthesis and purchase of analogs.

  2. An overview of cytokines and cytokine antagonists as therapeutic agents.

    PubMed

    Donnelly, Raymond P; Young, Howard A; Rosenberg, Amy S

    2009-12-01

    Cytokine-based therapies have the potential to provide novel treatments for cancer, autoimmune diseases, and many types of infectious disease. However, to date, the full clinical potential of cytokines as drugs has been limited by a number of factors. To discuss these limitations and explore ways to overcome them, the FDA partnered with the New York Academy of Sciences in March 2009 to host a two-day forum to discuss more effective ways to harness the clinical potential of cytokines and cytokine antagonists as therapeutic agents. The first day was focused primarily on the use of recombinant cytokines as therapeutic agents for treatment of human diseases. The second day focused largely on the use of cytokine antagonists as therapeutic agents for treatment of human diseases. This issue of the Annals includes more than a dozen papers that summarize much of the information that was presented during this very informative two-day conference.

  3. Lead Optimization Studies of Cinnamic Amide EP2 Antagonists

    PubMed Central

    2015-01-01

    Prostanoid receptor EP2 can play a proinflammatory role, exacerbating disease pathology in a variety of central nervous system and peripheral diseases. A highly selective EP2 antagonist could be useful as a drug to mitigate the inflammatory consequences of EP2 activation. We recently identified a cinnamic amide class of EP2 antagonists. The lead compound in this class (5d) displays anti-inflammatory and neuroprotective actions. However, this compound exhibited moderate selectivity to EP2 over the DP1 prostanoid receptor (∼10-fold) and low aqueous solubility. We now report compounds that display up to 180-fold selectivity against DP1 and up to 9-fold higher aqueous solubility than our previous lead. The newly developed compounds also display higher selectivity against EP4 and IP receptors and a comparable plasma pharmacokinetics. Thus, these compounds are useful for proof of concept studies in a variety of models where EP2 activation is playing a deleterious role. PMID:24773616

  4. Aryl Hydrocarbon Receptor Antagonists Promote the Expansion of Human Hematopoietic Stem Cells

    PubMed Central

    Boitano, Anthony E.; Wang, Jian; Romeo, Russell; Bouchez, Laure C.; Parker, Albert E.; Sutton, Sue E.; Walker, John R.; Flaveny, Colin A.; Perdew, Gary H.; Denison, Michael S.; Schultz, Peter G.; Cooke, Michael P.

    2011-01-01

    Although practiced clinically for over 40 years, the use of hematopoietic stem cell (HSC) transplants remains limited by the ability to expand these cells ex vivo. An unbiased screen with primary human HSC identified a purine derivative, StemRegenin 1 (SR1), that promotes the ex vivo expansion of CD34+ cells. Culture of HSC with SR1 led to a fifty-fold increase in cells expressing CD34, and a 17-fold increase in cells that retain the ability to engraft immunodeficient mice. Mechanistic studies show that SR1 acts by antagonizing the aryl hydrocarbon receptor (AhR). The identification of SR1 and AhR modulation as a means to induce ex vivo HSC expansion should facilitate the clinical use of HSC therapy. PMID:20688981

  5. [Leukotriene antagonists: a new approach in the treatment of asthma].

    PubMed

    Devillier, P; Bessard, G; Advenier, C

    1997-06-01

    Inflammation plays an essential role in the genesis of airflow obstruction and bronchial hyper-reactivity in the early stages of clinical asthma. The treatment of bronchial inflammation has become an essential element in the therapeutic strategy and principally rests on inhaled glucocorticoids. Amongst a number of inflammatory mediators leukotrienes occupy a privileged place by the power of their inflammatory and constrictor effects on bronchial smooth muscles. These properties have justified the clinical development of inhibitors of their synthesis and of specific antagonists to their receptors. Leukotriene antagonists are specific for a sub type of leukotriene receptors C4, D4 and E4 which is implicated in the majority of the bronchial constrictor and inflammatory effects of leukotrienes. The antagonists of Cys-LT1 receptor but also the inhibitors of the leukotriene synthesis exert an additive bronchodilator effect to those of B2 stimulants confirming an efficacious protection vis a vis bronchial provocation tests and above all they improve the clinical scores, lung function and also enable a decrease in the consumption of beta 2 agonists. The marketing of these products represents a major event because it corresponds to the advent of a new therapeutic class. The ease of administration by the oral route, their demonstrated efficacy and their good tolerance profile (in particular for ICI 204.219, and antagonists to Cys-LT1 receptors) are elements which foresee a success for this new asthmatic treatment. However numerous studies, notably comparative studies vis a vis reference treatments will be necessary to define their place in the strategic approach to the treatment of asthma.

  6. Effect of a Hypocretin/Orexin Antagonist on Neurocognitive Performance

    DTIC Science & Technology

    2012-09-01

    cells are more strongly activated by ZOL (Task 4a). Lesions of the basal forebrain (BF), a wakefulness-promoting area, potentiated the hypnotic ...receptor antagonist with a novel mechanism of action that has shown promise as an effective hypnotic . Preclinical data demonstrate that animals...results are consistent with the hypothesis that, although both ALM and ZOL are effective hypnotic medications, rats would show less functional impairment

  7. Neuronal Degeneration in the Cingulated Gyrus: NMDC Antagonists and Anticholinesterases

    DTIC Science & Technology

    2002-10-01

    exposure of these compounds to pyridostigmine bromide induce detectable neurotoxicity. 3) The NMDA receptor antagonist, memantine induces a neurotoxic...these drug combinations, suggesting this is a toxic combination. 4) The resultant neuropathology in MK-801 and memantine exposed animals is in good...agreement with the behavioral deficits exhibited by animals exposed to these compounds. 5) Combined exposure of memantine and PB had a greater effect on IPSPs than did memantine or PB alone.

  8. VLA-4 antagonists: potent inhibitors of lymphocyte migration.

    PubMed

    Yang, Ginger X; Hagmann, William K

    2003-05-01

    Circulating lymphocytes normally migrate through extravascular spaces in relatively low numbers as important members of the immunosurveillance process. That is until signals are received by endothelial cells that there is an underlying infection or inflammatory condition. These vascular surface cells in turn overexpress and present ligands to circulating lymphocyte adhesion molecules. Upon encountering this higher density of ligands, lymphocytes, which had been leisurely rolling along the vascular surface, now become more firmly attached, change shape, and migrate through tight junctions to the sites of infection or inflammation. If the initiating events are not resolved and the condition becomes chronic, there can be a sustained extravasation of lymphocytes that can exacerbate the inflammatory condition, which in turn will continue to recruit more inflammatory cells resulting in unwanted tissue destruction. It is for the attenuation of this cycle of sustained inflammatory cell recruitment that very late activating antigen-4 (VLA-4) antagonists are being developed. Most lymphocytes, except neutrophils, express VLA-4 on their surface and they interact with endothelial vascular cell adhesion molecule-1 (VCAM-1). It is this interaction that VLA-4 antagonists are intended to disrupt, thus, putting an end to the cycle of chronic inflammation, which is the hallmark of many diseases. This review will provide an update of VLA-4 antagonists that have appeared since early 2001 and will discuss some of the issues, both positive and negative, that may be encountered in their development. Copyright 2003 Wiley Periodicals, Inc.

  9. Vasopressin antagonists as aquaretic agents for the treatment of hyponatremia.

    PubMed

    Palm, Catrin; Pistrosch, Frank; Herbrig, Kay; Gross, Peter

    2006-07-01

    Hyponatremia is the most frequent electrolyte disorder encountered in hospitalized patients. It is a state of relative water excess due to stimulated arginine vasopressin (AVP) and fluid intake greater than obligatory losses. This kind of hyponatremia occurs in the syndrome of inappropriate antidiuretic hormone secretion, congestive heart failure, and liver cirrhosis. Fluid restriction is the presently recommended treatment for hyponatremia. However, fluid restriction may be very difficult for patients to achieve, is slow to work, and does not allow a graded therapeutic approach. More efficient and specific treatments of hyponatremia are needed. In this respect, pharmacologic research has yielded a number of compounds exhibiting antagonistic qualities at the vasopressin V2 receptor. Among these agents, peptidic derivatives of AVP turned out to have intrinsic antidiuretic properties in vivo when given over days or weeks. The development of such agents for use in patients has not been pursued. However, several promising nonpeptide, vasopressin receptor antagonists have been described; these agents are VPA-985 (lixivaptan), YM-087 (conivaptan), OPC-41061 (tolvaptan), and SR-121463. Prospective, randomized, placebo-controlled trials performed with these agents found that they corrected hyponatremia efficiently and safely. Most of the studies were conducted over a 4- to 28-day period. Long-term studies will be needed in the future to address such issues as the eventual benefit to patients and the effects of vasopressin antagonists on morbidity and mortality of patients with hyponatremia.

  10. Toxicological Differences Between NMDA Receptor Antagonists and Cholinesterase Inhibitors.

    PubMed

    Shi, Xiaodong; Lin, Xiaotian; Hu, Rui; Sun, Nan; Hao, Jingru; Gao, Can

    2016-08-01

    Cholinesterase inhibitors (ChEIs), represented by donepezil, rivastigmine, and galantamine, used to be the only approved class of drugs for the treatment of Alzheimer's disease. After the approval of memantine by the Food and Drug Administration (FDA), N-methyl-d-aspartic acid (NMDA) receptor antagonists have been recognized by authorities and broadly used in the treatment of Alzheimer's disease. Along with complementary mechanisms of action, NMDA antagonists and ChEIs differ not only in therapeutic effects but also in adverse reactions, which is an important consideration in clinical drug use. And the number of patients using NMDA antagonists and ChEIs concomitantly has increased, making the matter more complicated. Here we used the FDA Adverse Event Reporting System for statistical analysis , in order to compare the adverse events of memantine and ChEIs. In general, the clinical evidence confirmed the safety advantages of memantine over ChEIs, reiterating the precautions of clinical drug use and the future direction of antidementia drug development. © The Author(s) 2016.

  11. μ Opioid receptor: novel antagonists and structural modeling

    NASA Astrophysics Data System (ADS)

    Kaserer, Teresa; Lantero, Aquilino; Schmidhammer, Helmut; Spetea, Mariana; Schuster, Daniela

    2016-02-01

    The μ opioid receptor (MOR) is a prominent member of the G protein-coupled receptor family and the molecular target of morphine and other opioid drugs. Despite the long tradition of MOR-targeting drugs, still little is known about the ligand-receptor interactions and structure-function relationships underlying the distinct biological effects upon receptor activation or inhibition. With the resolved crystal structure of the β-funaltrexamine-MOR complex, we aimed at the discovery of novel agonists and antagonists using virtual screening tools, i.e. docking, pharmacophore- and shape-based modeling. We suggest important molecular interactions, which active molecules share and distinguish agonists and antagonists. These results allowed for the generation of theoretically validated in silico workflows that were employed for prospective virtual screening. Out of 18 virtual hits evaluated in in vitro pharmacological assays, three displayed antagonist activity and the most active compound significantly inhibited morphine-induced antinociception. The new identified chemotypes hold promise for further development into neurochemical tools for studying the MOR or as potential therapeutic lead candidates.

  12. Substance P antagonists and mucociliary activity in rabbit.

    PubMed

    Lindberg, S; Mercke, U

    1985-06-01

    Substance P (SP) is known to accelerate mucociliary (m.c.) activity in the rabbit maxillary sinus in vivo. The physiological significance of this finding was investigated by testing three putative SP antagonists. [Arg5, D-Trp7,9, Nle11]SP5-11 could not be used as an antagonist because it stimulated m.c. activity. [D-Arg1, D-Trp7,9, Leu11]SP had no effect on the m.c. activity changes induced by SP. [D-Pro2, D-Trp7,9]SP was found to be an effective antagonist, 1 mg/kg of this drug reversibly inhibiting both the effects of 0.1 micrograms/kg SP and the stimulating effect of 1.0 micrograms/kg bradykinin and 30.0 micrograms/kg capsaicin; the stimulating effect of 0.5 micrograms/kg methacholine was not inhibited. It is suggested that bradykinin and capsaicin stimulate m.c. activity at least partly by releasing SP. The results of this investigation also support the view that the accelerating effect of SP on m.c. activity reflects physiological SP-mediated protective mechanisms in the airways. It is concluded that [D-Pro2,D-Trp7,9]SP is a useful pharmacological tool for studying the role of SP in the control of m.c. activity in rabbits.

  13. In vivo effects of a GPR30 antagonist.

    PubMed

    Dennis, Megan K; Burai, Ritwik; Ramesh, Chinnasamy; Petrie, Whitney K; Alcon, Sara N; Nayak, Tapan K; Bologa, Cristian G; Leitao, Andrei; Brailoiu, Eugen; Deliu, Elena; Dun, Nae J; Sklar, Larry A; Hathaway, Helen J; Arterburn, Jeffrey B; Oprea, Tudor I; Prossnitz, Eric R

    2009-06-01

    Estrogen is central to many physiological processes throughout the human body. We have previously shown that the G protein-coupled receptor GPR30 (also known as GPER), in addition to classical nuclear estrogen receptors (ER and ER), activates cellular signaling pathways in response to estrogen. In order to distinguish between the actions of classical estrogen receptors and GPR30, we have previously characterized G-1 (1), a selective agonist of GPR30. To complement the pharmacological properties of G-1, we sought to identify an antagonist of GPR30 that displays similar selectivity against the classical estrogen receptors. Here we describe the identification and characterization of G15 (2), a G-1 analog that binds to GPR30 with high affinity and acts as an antagonist of estrogen signaling through GPR30. In vivo administration of G15 revealed that GPR30 contributes to both uterine and neurological responses initiated by estrogen. The identification of this antagonist will accelerate the evaluation of the roles of GPR30 in human physiology.

  14. Role of muscarinic receptor antagonists in urgency and nocturia.

    PubMed

    Michel, Martin C; de la Rosette, Jean J M C H

    2005-09-01

    The overactive bladder (OAB) syndrome is defined as urgency, with or without urgency incontinence, usually accompanied by frequency and nocturia. Muscarinic receptor antagonists are the most established form of treatment for OAB, but until recently their effectiveness was only confirmed for symptoms of incontinence and frequency. In recent studies, selected muscarinic antagonists, including darifenacin, solifenacin, tolterodine and trospium, significantly reduced the number of urgency episodes per day relative to placebo. While some data raise the possibility that certain of these agents may be more effective than others in this regard, this variability in their effect on urgency needs to be confirmed in future studies. Moreover, it remains to be determined whether counting the number of urgency episodes or assessing the subjective intensity of the sensation of urgency more adequately reflects patient needs and therapeutic efficacy. For nocturia, muscarinic receptor antagonists have only inconsistently shown statistically greater effects than placebo. This inconsistency may relate to the multifactorial nature of nocturia, which even in patients with OAB can have many causes, not all of which may respond/be sensitive to muscarinic receptor antagonism.

  15. Models for H₃ receptor antagonist activity of sulfonylurea derivatives.

    PubMed

    Khatri, Naveen; Madan, A K

    2014-03-01

    The histamine H₃ receptor has been perceived as an auspicious target for the treatment of various central and peripheral nervous system diseases. In present study, a wide variety of 60 2D and 3D molecular descriptors (MDs) were successfully utilized for the development of models for the prediction of antagonist activity of sulfonylurea derivatives for histamine H₃ receptors. Models were developed through decision tree (DT), random forest (RF) and moving average analysis (MAA). Dragon software version 6.0.28 was employed for calculation of values of diverse MDs of each analogue involved in the data set. The DT classified and correctly predicted the input data with an impressive non-error rate of 94% in the training set and 82.5% during cross validation. RF correctly classified the analogues into active and inactive with a non-error rate of 79.3%. The MAA based models predicted the antagonist histamine H₃ receptor activity with non-error rate up to 90%. Active ranges of the proposed MAA based models not only exhibited high potency but also showed improved safety as indicated by relatively high values of selectivity index. The statistical significance of the models was assessed through sensitivity, specificity, non-error rate, Matthew's correlation coefficient and intercorrelation analysis. Proposed models offer vast potential for providing lead structures for development of potent but safe H₃ receptor antagonist sulfonylurea derivatives. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Microbial Herd Protection Mediated by Antagonistic Interaction in Polymicrobial Communities

    PubMed Central

    Wong, Megan J. Q.; Liang, Xiaoye; Smart, Matt; Tang, Le; Moore, Richard; Ingalls, Brian

    2016-01-01

    ABSTRACT In host and natural environments, microbes often exist in complex multispecies communities. The molecular mechanisms through which such communities develop and persist, despite significant antagonistic interactions between species, are not well understood. The type VI secretion system (T6SS) is a lethal weapon commonly employed by Gram-negative bacteria to inhibit neighboring species through the delivery of toxic effectors. It is well established that intraspecies protection is conferred by immunity proteins that neutralize effector toxicities. In contrast, the mechanisms for interspecies protection are not clear. Here we use two T6SS-active antagonistic bacterial species, Aeromonas hydrophila and Vibrio cholerae, to demonstrate that interspecies protection is dependent on effectors. A. hydrophila and V. cholerae do not share conserved immunity genes but could coexist equally in a mixture. However, mutants lacking the T6SS or effectors were effectively eliminated by the competing wild-type strain. Time-lapse microscopic analyses showed that mutually lethal interactions drive the segregation of mixed species into distinct single-species clusters by eliminating interspersed single cells. Cluster formation provides herd protection by abolishing lethal interactions inside each cluster and restricting the interactions to the boundary. Using an agent-based modeling approach, we simulated the antagonistic interactions of two hypothetical species. The resulting simulations recapitulated our experimental observations. These results provide mechanistic insights regarding the general role of microbial weapons in determining the structures of complex multispecies communities. IMPORTANCE Investigating the warfare of microbes allows us to better understand the ecological relationships in complex microbial communities such as the human microbiota. Here we use the T6SS, a deadly bacterial weapon, as a model to demonstrate the importance of lethal interactions in

  17. Microbial herd protection mediated by antagonistic interaction in polymicrobial communities.

    PubMed

    Wong, Megan; Liang, Xiaoye; Smart, Matt; Tang, Le; Moore, Richard; Ingalls, Brian; Dong, Tao G

    2016-09-16

    In the host and natural environments, microbes often exist in complex multispecies communities. The molecular mechanisms through which such communities develop and persist - despite significant antagonistic interactions between species - are not well understood. The type VI secretion system (T6SS) is a lethal weapon commonly employed by Gram-negative bacteria to inhibit neighboring species through delivery of toxic effectors. It is well established that intra-species protection is conferred by immunity proteins that neutralize effector toxicities. By contrast, the mechanisms for interspecies protection are not clear. Here we use two T6SS active antagonistic bacteria, Aeromonas hydrophila (AH) and Vibrio cholerae (VC), to demonstrate that interspecies protection is dependent on effectors. AH and VC do not share conserved immunity genes but could equally co-exist in a mixture. However, mutants lacking the T6SS or effectors were effectively eliminated by the other competing wild type. Time-lapse microscopy analyses show that mutually lethal interactions drive the segregation of mixed species into distinct single-species clusters by eliminating interspersed single cells. Cluster formation provides herd protection by abolishing lethal interaction inside each cluster and restricting it to the boundary. Using an agent-based modeling approach, we simulated the antagonistic interactions of two hypothetical species. The resulting simulations recapitulate our experimental observation. These results provide mechanistic insights for the general role of microbial weapons in determining the structures of complex multispecies communities. Investigating the warfare of microbes allows us to better understand the ecological relationships in complex microbial communities such as the human microbiota. Here we use the T6SS, a deadly bacterial weapon, as a model to demonstrate the importance of lethal interactions in determining community structures and exchange of genetic materials

  18. Arginine mimetic structures in biologically active antagonists and inhibitors.

    PubMed

    Masic, Lucija Peterlin

    2006-01-01

    Peptidomimetics have found wide application as bioavailable, biostable, and potent mimetics of naturally occurring biologically active peptides. L-Arginine is a guanidino group-containing basic amino acid, which is positively charged at neutral pH and is involved in many important physiological and pathophysiological processes. Many enzymes display a preference for the arginine residue that is found in many natural substrates and in synthetic inhibitors of many trypsin-like serine proteases, e.g. thrombin, factor Xa, factor VIIa, trypsin, and in integrin receptor antagonists, used to treat many blood-coagulation disorders. Nitric oxide (NO), which is produced by oxidation of L-arginine in an NADPH- and O(2)-dependent process catalyzed by isoforms of nitric oxide synthase (NOS), exhibits diverse roles in both normal and pathological physiologies and has been postulated to be a contributor to the etiology of various diseases. Development of NOS inhibitors as well as analogs and mimetics of the natural substrate L-arginine, is desirable for potential therapeutic use and for a better understanding of their conformation when bound in the arginine binding site. The guanidino residue of arginine in many substrates, inhibitors, and antagonists forms strong ionic interactions with the carboxylate of an aspartic acid moiety, which provides specificity for the basic amino acid residue in the active side. However, a highly basic guanidino moiety incorporated in enzyme inhibitors or receptor antagonists is often associated with low selectivity and poor bioavailability after peroral application. Thus, significant effort is focused on the design and preparation of arginine mimetics that can confer selective inhibition for specific trypsin-like serine proteases and NOS inhibitors as well as integrin receptor antagonists and possess reduced basicity for enhanced oral bioavailability. This review will describe the survey of arginine mimetics designed to mimic the function of the

  19. Antagonist-perturbation mechanism for activation function-2 fixed motifs: active conformation and docking mode of retinoid X receptor antagonists

    NASA Astrophysics Data System (ADS)

    Tsuji, Motonori

    2017-06-01

    HX531, which contains a dibenzodiazepine skeleton, is one of the first retinoid X receptor (RXR) antagonists. Functioning via RXR-PPARγ heterodimer, this compound is receiving a lot of attention as a therapeutic drug candidate for diabetic disease controlling differentiation of adipose tissue. However, the active conformation of HX531 for RXRs is not well established. In the present study, quantum mechanics calculations and molecular mechanical docking simulations were carried out to precisely study the docking mode of HX531 with the human RXRα ligand-binding domain, as well as to provide a new approach to drug design using a structure-based perspective. It was suggested that HX531, which has the R configuration for the bent dibenzodiazepine plane together with the equatorial configuration for the N-methyl group attached to the nitrogen atom in the seven-membered diazepine ring, is a typical activation function-2 (AF-2) fixed motif perturbation type antagonist, which destabilizes the formation of AF-2 fixed motifs. On the other hand, the docking simulations supported the experimental result that LG100754 is an RXR homodimer antagonist and an RXR heterodimer agonist.

  20. Plant polyphenols differentially modulate inflammatory responses of human keratinocytes by interfering with activation of transcription factors NF{kappa}B and AhR and EGFR-ERK pathway

    SciTech Connect

    Potapovich, Alla I.; Biology Department, Belarus State University, Skorina Prosp. 10, Minsk 220050; Lulli, Daniela

    Molecular mechanisms underlying modulation of inflammatory responses in primary human keratinocytes by plant polyphenols (PPs), namely the glycosylated phenylpropanoid verbascoside, the stilbenoid resveratrol and its glycoside polydatin, and the flavonoid quercetin and its glycoside rutin were evaluated. As non-lethal stimuli, the prototypic ligand for epidermal growth factor receptor (EGFR) transforming growth factor alpha (TGFalpha), the combination of tumor necrosis factor (TNFalpha) and interferon (IFNgamma) (T/I), UVA + UVB irradiation, and bacterial lipopolysaccharide (LPS) were used. We demonstrated differential modulation of inflammatory responses in keratinocytes at signal transduction, gene transcription, and protein synthesis levels as a function of PP chemical structure,more » the pro-inflammatory trigger used, and PP interaction with intracellular detoxifying systems. The PPs remarkably inhibited constitutive, LPS- and T/I-induced but not TGFalpha-induced ERK phosphorylation. They also suppressed NFkappaB activation by LPS and T/I. Verbascoside and quercetin invariably impaired EGFR phosphorylation and UV-associated aryl hydrocarbon receptor (AhR)-mediated signaling, while rutin, polydatin and resveratrol did not affect EGFR phosphorylation and further activated AhR machinery in UV-exposed keratinocytes. In general, PPs down-regulated gene expression of pro-inflammatory cytokines/enzymes, except significant up-regulation of IL-8 observed under stimulation with TGFalpha. Both spontaneous and T/I-induced release of IL-8 and IP-10 was suppressed, although 50 {mu}M resveratrol and polydatin up-regulated IL-8. At this concentration, resveratrol activated both gene expression and de novo synthesis of IL-8 and AhR-mediated mechanisms were involved. We conclude that PPs differentially modulate the inflammatory response of human keratinocytes through distinct signal transduction pathways, including AhR and EGFR. - Graphical abstract: Display Omitted

  1. Th2 cytokine antagonists: potential treatments for severe asthma.

    PubMed

    Hansbro, Philip M; Scott, Grace V; Essilfie, Ama-Tawiah; Kim, Richard Y; Starkey, Malcolm R; Nguyen, Duc H; Allen, Paul D; Kaiko, Gerard E; Yang, Ming; Horvat, Jay C; Foster, Paul S

    2013-01-01

    Asthma is a major disease burden worldwide. Treatment with steroids and long acting β-agonists effectively manage symptoms in many patients but do not treat the underlying cause of disease and have serious side effects when used long term and in children. Therapies targeting the underlying causes of asthma are urgently needed. T helper type 2 (Th2) cells and the cytokines they release are clinically linked to the presentation of all forms of asthma. They are the primary drivers of mild to moderate and allergic asthma. They also play a pathogenetic role in exacerbations and more severe asthma though other factors are also involved. Much effort using animal models and human studies has been dedicated to the identification of the pathogenetic roles of these cells and cytokines and whether inhibition of their activity has therapeutic benefit in asthma. We discuss the current status of Th2 cytokine antagonists for the treatment of asthma. We also discuss the potential for targeting Th2-inducing cytokines, Th2 cell receptors and signaling as well as the use of Th2 cell antagonists, small interfering oligonucleotides, microRNAs, and combination therapies. Th2 antagonists may be most effective in particular asthma subtypes/endotypes where specific cytokines are known to be active through the analysis of biomarkers. Targeting common receptors and pathways used by these cytokines may have additional benefit. Animal models have been valuable in identifying therapeutic targets in asthma, however the results from such studies need to be carefully interpreted and applied to appropriately stratified patient cohorts in well-designed clinical studies and trials.

  2. Classification and virtual screening of androgen receptor antagonists.

    PubMed

    Li, Jiazhong; Gramatica, Paola

    2010-05-24

    Computational tools, such as quantitative structure-activity relationship (QSAR), are highly useful as screening support for prioritization of substances of very high concern (SVHC). From the practical point of view, QSAR models should be effective to pick out more active rather than inactive compounds, expressed as sensitivity in classification works. This research investigates the classification of a big data set of endocrine-disrupting chemicals (EDCs)-androgen receptor (AR) antagonists, mainly aiming to improve the external sensitivity and to screen for potential AR binders. The kNN, lazy IB1, and ADTree methods and the consensus approach were used to build different models, which improve the sensitivity on external chemicals from 57.1% (literature) to 76.4%. Additionally, the models' predictive abilities were further validated on a blind collected data set (sensitivity: 85.7%). Then the proposed classifiers were used: (i) to distinguish a set of AR binders into antagonists and agonists; (ii) to screen a combined estrogen receptor binder database to find out possible chemicals that can bind to both AR and ER; and (iii) to virtually screen our in-house environmental chemical database. The in silico screening results suggest: (i) that some compounds can affect the normal endocrine system through a complex mechanism binding both to ER and AR; (ii) new EDCs, which are nonER binders, but can in silico bind to AR, are recognized; and (iii) about 20% of compounds in a big data set of environmental chemicals are predicted as new AR antagonists. The priority should be given to them to experimentally test the binding activities with AR.

  3. Virtual High-Throughput Screening To Identify Novel Activin Antagonists

    PubMed Central

    Zhu, Jie; Mishra, Rama K.; Schiltz, Gary E.; Makanji, Yogeshwar; Scheidt, Karl A.; Mazar, Andrew P.; Woodruff, Teresa K.

    2015-01-01

    Activin belongs to the TGFβ superfamily, which is associated with several disease conditions, including cancer-related cachexia, preterm labor with delivery, and osteoporosis. Targeting activin and its related signaling pathways holds promise as a therapeutic approach to these diseases. A small-molecule ligand-binding groove was identified in the interface between the two activin βA subunits and was used for a virtual high-throughput in silico screening of the ZINC database to identify hits. Thirty-nine compounds without significant toxicity were tested in two well-established activin assays: FSHβ transcription and HepG2 cell apoptosis. This screening workflow resulted in two lead compounds: NUCC-474 and NUCC-555. These potential activin antagonists were then shown to inhibit activin A-mediated cell proliferation in ex vivo ovary cultures. In vivo testing showed that our most potent compound (NUCC-555) caused a dose-dependent decrease in FSH levels in ovariectomized mice. The Blitz competition binding assay confirmed target binding of NUCC-555 to the activin A:ActRII that disrupts the activin A:ActRII complex’s binding with ALK4-ECD-Fc in a dose-dependent manner. The NUCC-555 also specifically binds to activin A compared with other TGFβ superfamily member myostatin (GDF8). These data demonstrate a new in silico-based strategy for identifying small-molecule activin antagonists. Our approach is the first to identify a first-in-class small-molecule antagonist of activin binding to ALK4, which opens a completely new approach to inhibiting the activity of TGFβ receptor superfamily members. in addition, the lead compound can serve as a starting point for lead optimization toward the goal of a compound that may be effective in activin-mediated diseases. PMID:26098096

  4. Behavioral approach to nondyskinetic dopamine antagonists: identification of seroquel.

    PubMed

    Warawa, E J; Migler, B M; Ohnmacht, C J; Needles, A L; Gatos, G C; McLaren, F M; Nelson, C L; Kirkland, K M

    2001-02-01

    A great need exists for antipsychotic drugs which will not induce extrapyramidal symptoms (EPS) and tardive dyskinesias (TDs). These side effects are deemed to be a consequence of nonselective blockade of nigrostriatal and mesolimbic dopamine D2 receptors. Nondyskinetic clozapine (1) is a low-potency D2 dopamine receptor antagonist which appears to act selectively in the mesolimbic area. In this work dopamine antagonism was assessed in two mouse behavioral assays: antagonism of apomorphine-induced climbing and antagonism of apomorphine-induced disruption of swimming. The potential for the liability of dyskinesias was determined in haloperidol-sensitized Cebus monkeys. Initial examination of a few close cogeners of 1 enhanced confidence in the Cebus model as a predictor of dyskinetic potential. Considering dibenzazepines, 2 was not dyskinetic whereas 2a was dyskinetic. Among dibenzodiazepines, 1 did not induce dyskinesias whereas its N-2-(2-hydroxyethoxy)ethyl analogue 3 was dyskinetic. The emergence of such distinctions presented an opportunity. Thus, aromatic and N-substituted analogues of 6-(piperazin-1-yl)-11H-dibenz[b,e]azepines and 11-(piperazin-1-yl)dibenzo[b,f][1,4]thiazepines and -oxazepines were prepared and evaluated. 11-(4-[2-(2-Hydroxyethoxy)ethyl]piperazin-1-yl)dibenzo[b,f][1,4]thiazepine (23) was found to be an apomorphine antagonist comparable to clozapine. It was essentially nondyskinetic in the Cebus model. With 23 as a platform, a number of N-substituted analogues were found to be good apomorphine antagonists but all were dyskinetic.

  5. Competitive antagonists discriminate between NK2 tachykinin receptor subtypes.

    PubMed Central

    Maggi, C. A.; Patacchini, R.; Giuliani, S.; Rovero, P.; Dion, S.; Regoli, D.; Giachetti, A.; Meli, A.

    1990-01-01

    1. We have compared the ability of various tachykinins and selective tachykinin receptor agonists to induce contraction of the endothelium-denuded rabbit pulmonary artery (RPA) and hamster trachea (HT) and have estimated the affinity of some newly developed NK2 selective antagonists in the same tissues. 2. In confirmation of previous findings, experiments with the agonists indicated that NK2 receptors are the main if not the sole mediators of the response to tachykinins in both RPA and HT. No evidence for significant degradation of neurokinin A (NKA) was found in either tissue when experiments were repeated in the presence of a mixture of peptidase inhibitors (thiorphan, captopril and bestatin, 1 microM each). 3. The peptide antagonists tested were: Peptide I = [Tyr5, D-Trp6,8,9, Arg10]-NKA(4-10); Peptide II = [Tyr5, D-Trp6,8,9, Arg10]-NKA(3-10); Peptide III = Ac-Leu-Asp-Gln-Trp-Phe-Gly-NH2. The three peptides produced a concentration-dependent rightward shift of the concentration-response curve to NKA in both RPA and HT with no significant depression of the maximal response attainable. The slopes of the Schild plots were not significantly different from unity, indicating a competitive antagonism. Peptides I and II were about 100 times more potent in the RPA than in the HT, while Peptide III was about 100 times more potent in the HT than RPA. 4. The pA2 values obtained in these two tissues with the three antagonists were not significantly different when tested in the absence or presence of peptidase inhibitors, or when a selective NK2 receptor agonist, [beta Ala8]-NKA(4-10) was used instead of NKA.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2167737

  6. Depressive-like effect of prenatal exposure to DDT involves global DNA hypomethylation and impairment of GPER1/ESR1 protein levels but not ESR2 and AHR/ARNT signaling.

    PubMed

    Kajta, Malgorzata; Wnuk, Agnieszka; Rzemieniec, Joanna; Litwa, Ewa; Lason, Wladyslaw; Zelek-Molik, Agnieszka; Nalepa, Irena; Rogóż, Zofia; Grochowalski, Adam; Wojtowicz, Anna K

    2017-07-01

    Several lines of evidence suggest that exposures to Endocrine Disrupting Chemicals (EDCs) such as pesticides increase the risks of neuropsychiatric disorders. Despite extended residual persistence of dichlorodiphenyltrichloroethane (DDT) in the environment, the mechanisms of perinatal actions of DDT that could account for adult-onset of depression are largely unknown. This study demonstrated the isomer-specific induction of depressive-like behavior and impairment of Htr1a/serotonin signaling in one-month-old mice that were prenatally exposed to DDT. The effects were reversed by the antidepressant citalopram as evidenced in the forced swimming (FST) and tail suspension (TST) tests in the male and female mice. Prenatally administered DDT accumulated in mouse brain as determined with gas chromatography and tandem mass spectrometry, led to global DNA hypomethylation, and altered the levels of methylated DNA in specific genes. The induction of depressive-like behavior and impairment of Htr1a/serotonin signaling were accompanied by p,p'-DDT-specific decrease in the levels of estrogen receptors i.e. ESR1 and/or GPER1 depending on sex. In contrast, o,p'-DDT did not induce depressive-like effects and exhibited quite distinct pattern of biochemical alterations that was related to aryl hydrocarbon receptor (AHR), its nuclear translocator ARNT, and ESR2. Exposure to o,p'-DDT increased AHR expression in male and female brains, and reduced expression levels of ARNT and ESR2 in the female brains. The evolution of p,p'-DDT-induced depressive-like behavior was preceded by attenuation of Htr1a and Gper1/GPER1 expression as observed in the 7-day-old mouse pups. Because p,p'-DDT caused sex- and age-independent attenuation of GPER1, we suggest that impairment of GPER1 signaling plays a key role in the propagation of DDT-induced depressive-like symptoms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Dose- and time-dependent expression of aryl hydrocarbon receptor (AhR) and aryl hydrocarbon receptor nuclear translocator (ARNT) in PCB-, B[a]P-, and TBT-exposed intertidal copepod Tigriopus japonicus.

    PubMed

    Kim, Bo-Mi; Rhee, Jae-Sung; Hwang, Un-Ki; Seo, Jung Soo; Shin, Kyung-Hoon; Lee, Jae-Seong

    2015-02-01

    The aryl hydrocarbon receptor (AhR) and aryl hydrocarbon nuclear translocator (ARNT) genes from the copepod Tigriopus japonicus (Tj) were cloned to examine their potential functions in the invertebrate putative AhR-CYP signaling pathway. The amino acid sequences encoded by the Tj-AhR and Tj-ARNT genes showed high similarity to homologs of Daphnia and Drosophila, ranging from 68% and 70% similarity for the AhR genes to 56% for the ARNT genes. To determine whether Tj-AhR and Tj-ARNT are modulated by environmental pollutants, transcriptional expression of Tj-AhR and Tj-ARNT was analyzed in response to exposure to five concentrations of polychlorinated biphenyl (PCB 126) (control, 10, 50, 100, 500 μg L(-1)), benzo[a]pyrene (B[a]P) (control, 5, 10, 50, 100 μg L(-1)), and tributyltin (TBT) (control, 1, 5, 10, 20 μg L(-1)) 24h after exposure. A time-course experiment (0, 3, 6, 12, 24h) was performed to analyze mRNA expression patterns after exposure to PCB, B[a]P, and TBT. T. japonicus exhibited dose-dependent and time-dependent upregulation of Tj-AhR and Tj-ARNT in response to pollutant exposure, and the degree of expression was dependent on the pollutant, suggesting that pollutants such as PCB, B[a]P, and TBT modulate expression of Tj-AhR and Tj-ARNT genes in the putative AhR-CYP signaling pathway. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Discovery of a Series of Indazole TRPA1 Antagonists

    PubMed Central

    2017-01-01

    A series of TRPA1 antagonists is described which has as its core structure an indazole moiety. The physical properties and in vitro DMPK profiles are discussed. Good in vivo exposure was obtained with several analogs, allowing efficacy to be assessed in rodent models of inflammatory pain. Two compounds showed significant activity in these models when administered either systemically or topically. Protein chimeras were constructed to indicate compounds from the series bound in the S5 region of the channel, and a computational docking model was used to propose a binding mode for example compounds. PMID:28626530

  9. Effect of a Hypocretin/Orexin Antagonist on Neurocogniive Performance

    DTIC Science & Technology

    2014-09-01

    time: Tuesday , Nov 12, 2013, 4:00 PM - 5:00 PM Topic: ++E.08.e Sleep: Systems and behavior Authors: W. LINCOLN1, J. PALMERSTON1, T. NEYLAN2, T...functional impairment results from HcrtR antagonist-induced sleep, we evaluated the performance of rats in the Morris Water Maze in the presence of ALM vs. ZOL... Morris Water Maze. Although the concentrations of ALM and ZOL adminis- tered prior to these tests were equipotent in hypnotic efficacy, the

  10. Potential Antagonist of Folic Acid Metabolism as Malarial Drugs,

    DTIC Science & Technology

    1982-09-01

    which sen.irited from the hydrocloric acid was filtered and then washed with water (25 ml). The reaction gave 2.3 g of the product which melted be...neutralized with cold dilute hydrocloric acid and evaporated to dryness. The residue was then extracted with methylene chloride filtered, and again...FhGh6/15hEE 1281 12.5 ~I1.50 IIA 132ii MJCRc)tll I’RE SOLU i UN ltIS CHiARI AD FINAL REPORT POTENTIAL ANTAGONIST OF FOLIC ACID METABOLISM AS MALARIAL

  11. Membrane formation in liquids by adding an antagonistic salt

    NASA Astrophysics Data System (ADS)

    Sadakane, Koichiro; Seto, Hideki

    2018-03-01

    Antagonistic salts are composed of hydrophilic and hydrophobic ions. In a binary mixture, such as water and organic solvent, these ion pairs preferentially dissolve to those phases, respectively, and there is a coupling between the charge density and the composition. The heterogeneous distribution of ions forms a large electric double layer at the interface between these solvents. This reduces the interfacial tension between water and organic solvent, and stabilizes an ordered structure, such as a membrane. These phenomena have been extensively studied from both theoretical and experimental point of view. In addition, the numerical simulations can reproduce such ordered structures.

  12. The discovery of tropane-derived CCR5 receptor antagonists.

    PubMed

    Armour, Duncan R; de Groot, Marcel J; Price, David A; Stammen, Blanda L C; Wood, Anthony; Perros, Manos; Burt, Catherine

    2006-04-01

    The development of compound 1, a piperidine-based CCR5 receptor antagonist with Type I CYP2D6 inhibition, into the tropane-derived analogue 5, is described. This compound, which is devoid of CYP2D6 liabilities, is a highly potent ligand for the CCR5 receptor and has broad-spectrum activity against a range of clinically relevant HIV isolates. The identification of human ether a-go-go-related gene channel inhibition within this series is described and the potential for QTc interval prolongation discussed. Furthermore, structure activity relationship (SAR) around the piperidine moiety is also described.

  13. Esthetic Prosthetic Restorations: Reliability and Effects on Antagonist Dentition

    PubMed Central

    Daou, Elie E.

    2015-01-01

    Recent advances in ceramics have greatly improved the functional and esthetic properties of restorative materials. New materials offer an esthetic and functional oral rehabilitation, however their impact on opposing teeth is not welldocumented. Peer-reviewed articles published till December 2014 were identified through Pubmed (Medline and Elsevier). Scientifically, there are several methods of measuring the wear process of natural dentition which enhances the comparison of the complicated results. This paper presents an overview of the newly used prosthetic materials and their implication on antagonist teeth or prostheses, especially emphasizing the behavior of zirconia restorations. PMID:26962376

  14. Cocontraction of pairs of antagonistic muscles: analytical solution for planar static nonlinear optimization approaches.

    PubMed

    Herzog, W; Binding, P

    1993-11-01

    It has been stated in the literature that static, nonlinear optimization approaches cannot predict coactivation of pairs of antagonistic muscles; however, numerical solutions of such approaches have predicted coactivation of pairs of one-joint and multijoint antagonists. Analytical support for either finding is not available in the literature for systems containing more than one degree of freedom. The purpose of this study was to investigate analytically the possibility of cocontraction of pairs of antagonistic muscles using a static nonlinear optimization approach for a multidegree-of-freedom, two-dimensional system. Analytical solutions were found using the Karush-Kuhn-Tucker conditions, which were necessary and sufficient for optimality in this problem. The results show that cocontraction of pairs of one-joint antagonistic muscles is not possible, whereas cocontraction of pairs of multijoint antagonists is. These findings suggest that cocontraction of pairs of antagonistic muscles may be an "efficient" way to accomplish many movement tasks.

  15. The role of ecology, neutral processes and antagonistic coevolution in an apparent sexual arms race.

    PubMed

    Perry, Jennifer C; Garroway, Colin J; Rowe, Locke

    2017-09-01

    Some of the strongest examples of a sexual 'arms race' come from observations of correlated evolution in sexually antagonistic traits among populations. However, it remains unclear whether these cases truly represent sexually antagonistic coevolution; alternatively, ecological or neutral processes might also drive correlated evolution. To investigate these alternatives, we evaluated the contributions of intersex genetic correlations, ecological context, neutral genetic divergence and sexual coevolution in the correlated evolution of antagonistic traits among populations of Gerris incognitus water striders. We could not detect intersex genetic correlations for these sexually antagonistic traits. Ecological variation was related to population variation in the key female antagonistic trait (spine length, a defence against males), as well as body size. Nevertheless, population covariation between sexually antagonistic traits remained substantial and significant even after accounting for all of these processes. Our results therefore provide strong evidence for a contemporary sexual arms race. © 2017 John Wiley & Sons Ltd/CNRS.

  16. Combination cancer chemotherapy with one compound: pluripotent bradykinin antagonists.

    PubMed

    Stewart, John M; Gera, Lajos; Chan, Daniel C; York, Eunice J; Simkeviciene, Vitalija; Bunn, Paul A; Taraseviciene-Stewart, Laimute

    2005-08-01

    Lung and prostate cancers are major health problems worldwide. Treatments with standard chemotherapy agents are relatively ineffective. Combination chemotherapy gives better treatment than a single agent because the drugs can inhibit the cancer in different pathways, but new therapeutic agents are needed for the treatment of both tumor types. Bradykinin (BK) antagonists offer advantages of combination therapy in one compound. These promising multitargeted anti-cancer compounds selectively stimulate apoptosis in cancers and also inhibit both angiogenesis and matrix metalloprotease (MMP) action in treated lung and prostate tumors in nude mice. The highly potent, metabolism-resistant bradykinin antagonist peptide dimer, B-9870 [SUIM-(DArg-Arg-Pro-Hyp-Gly-Igl-Ser-DIgl-Oic-Arg)2] (SUIM=suberimidyl; Hyp=4-hydroxyproline; Igl=alpha-(2-indanyl)glycine; Oic=octahydroindole-2-carboxylic acid) and its non-peptide mimetic, BKM-570 [2,3,4,5,6-pentafluorocinnamoyl-(o-2,6-dichlorobenzyl)-L-tyrosine-N-(4-amino-2,2,6,6-tetramethylpiperidyl)amide] are superior to the widely used but toxic chemotherapeutic drugs cisplatin and taxotere. In certain combinations, they act synergistically with standard anti-cancer drugs. Due to its structure and biological activity, BKM-570 is an attractive lead compound for derivatization and evaluation for lung and prostate cancer drugs.

  17. Modulation of alcohol preference by NMDA antagonists in male rats.

    PubMed

    Lamblin, F; Deuceuninck, D; De Witte, P

    1993-11-01

    Chronic alcoholization by alcohol inhalation was used to study the properties of magnesium, a non-competitive NMDA receptor antagonist, and CGP 39551, a competitive NMDA receptor antagonist, on behavioural dependence as estimated by the free-choice paradigm [alcohol 10% (v/v) vs. water], on the hypermotility after alcohol withdrawal, and finally on the cortical vascularization. The first experimental group received the drugs per os during the whole alcoholization period. Magnesium (20 mg/kg/day) decreased the alcohol dependence while CGP 39551 (5 and 10 mg/kg/day) increased, in a dose-dependent manner, the dependence to alcohol. A second group of animals received the same drugs at the same dosages, not simultaneously during chronic alcoholization, but immediately after alcoholization in one shot i.p. injection. In this case, rats receiving 5 mg/kg CGP 39551 never showed any dependence towards alcohol, while 10 mg/kg CGP 39551 or 20 mg/kg magnesium prolonged the number of days of alcohol dependence. These results thus indicate the close interaction between NMDA receptor function and dependence for alcohol. Magnesium had no effects on hypermotility, while CGP 39551-treated animals presented a decrease in the hypermotility observed after alcohol withdrawal. Neither drug affected the hypervascularization accompanying the chronic alcoholization.

  18. Evolution of coreceptor utilization to escape CCR5 antagonist therapy.

    PubMed

    Zhang, Jie; Gao, Xiang; Martin, John; Rosa, Bruce; Chen, Zheng; Mitreva, Makedonka; Henrich, Timothy; Kuritzkes, Daniel; Ratner, Lee

    2016-07-01

    The HIV-1 envelope interacts with coreceptors CCR5 and CXCR4 in a dynamic, multi-step process, its molecular details not clearly delineated. Use of CCR5 antagonists results in tropism shift and therapeutic failure. Here we describe a novel approach using full-length patient-derived gp160 quasispecies libraries cloned into HIV-1 molecular clones, their separation based on phenotypic tropism in vitro, and deep sequencing of the resultant variants for structure-function analyses. Analysis of functionally validated envelope sequences from patients who failed CCR5 antagonist therapy revealed determinants strongly associated with coreceptor specificity, especially at the gp120-gp41 and gp41-gp41 interaction surfaces that invite future research on the roles of subunit interaction and envelope trimer stability in coreceptor usage. This study identifies important structure-function relationships in HIV-1 envelope, and demonstrates proof of concept for a new integrated analysis method that facilitates laboratory discovery of resistant mutants to aid in development of other therapeutic agents. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  19. The evolution of histamine H₃ antagonists/inverse agonists.

    PubMed

    Lebois, Evan P; Jones, Carrie K; Lindsley, Craig W

    2011-01-01

    This article describes our efforts along with recent advances in the development, biological evaluation and clinical proof of concept of small molecule histamine H₃ antagonists/inverse agonists. The H3 receptor is a presynaptic autoreceptor within the Class A GPCR family, but also functions as a heteroreceptor modulating levels of neurotransmitters such as dopamine, acetylcholine, norepinephrine, serotonin, GABA and glutamate. Thus, H₃R has garnered a great deal of interest from the pharmaceutical industry for the possible treatment of obesity, epilepsy, sleep/wake, schizophrenia, Alzheimer's disease, neuropathic pain and ADHD. Within the two main classes of H₃ ligands, both imidazole and non-imidazole derived, have shown sufficient potency and specificity which culminated with efficacy in preclinical models for various CNS disorders. Importantly, conserved elements have been identified within the small molecule H₃ ligand scaffolds that resulted in a highly predictive pharmacophore model. Understanding of the pharmacophore model has allowed several groups to dial H₃R activity into scaffolds designed for other CNS targets, and engender directed polypharmacology. Moreover, Abbott, GSK, Pfizer and several others have reported positive Phase I and/or Phase II data with structurally diverse H₃R antagonists/inverse agonists.

  20. Human homosexuality: a paradigmatic arena for sexually antagonistic selection?

    PubMed

    Camperio Ciani, Andrea; Battaglia, Umberto; Zanzotto, Giovanni

    2015-01-29

    Sexual conflict likely plays a crucial role in the origin and maintenance of homosexuality in our species. Although environmental factors are known to affect human homosexual (HS) preference, sibling concordances and population patterns related to HS indicate that genetic components are also influencing this trait in humans. We argue that multilocus, partially X-linked genetic factors undergoing sexually antagonistic selection that promote maternal female fecundity at the cost of occasional male offspring homosexuality are the best candidates capable of explaining the frequency, familial clustering, and pedigree asymmetries observed in HS male proband families. This establishes male HS as a paradigmatic example of sexual conflict in human biology. HS in females, on the other hand, is currently a more elusive phenomenon from both the empirical and theoretical standpoints because of its fluidity and marked environmental influence. Genetic and epigenetic mechanisms, the latter involving sexually antagonistic components, have been hypothesized for the propagation and maintenance of female HS in the population. However, further data are needed to truly clarify the evolutionary dynamics of this trait. Copyright © 2015 Cold Spring Harbor Laboratory Press; all rights reserved.

  1. Human Homosexuality: A Paradigmatic Arena for Sexually Antagonistic Selection?

    PubMed Central

    Ciani, Andrea Camperio; Battaglia, Umberto; Zanzotto, Giovanni

    2015-01-01

    Sexual conflict likely plays a crucial role in the origin and maintenance of homosexuality in our species. Although environmental factors are known to affect human homosexual (HS) preference, sibling concordances and population patterns related to HS indicate that genetic components are also influencing this trait in humans. We argue that multilocus, partially X-linked genetic factors undergoing sexually antagonistic selection that promote maternal female fecundity at the cost of occasional male offspring homosexuality are the best candidates capable of explaining the frequency, familial clustering, and pedigree asymmetries observed in HS male proband families. This establishes male HS as a paradigmatic example of sexual conflict in human biology. HS in females, on the other hand, is currently a more elusive phenomenon from both the empirical and theoretical standpoints because of its fluidity and marked environmental influence. Genetic and epigenetic mechanisms, the latter involving sexually antagonistic components, have been hypothesized for the propagation and maintenance of female HS in the population. However, further data are needed to truly clarify the evolutionary dynamics of this trait. PMID:25635045

  2. NMDA receptor antagonists extend the sensitive period for imprinting.

    PubMed

    Parsons, C H; Rogers, L J

    2000-03-01

    Filial imprinting in the domestic chick occurs during a sensitive period of development. The exact timing of this period can vary according to the methods used to measure imprinting. Using our imprinting paradigm, we have shown that normal, dark-reared chicks lose the ability to imprint after the second day post-hatching. Further, we reported that chicks treated 10 h after hatching with a mixture of the noncompetitive NMDA receptor antagonist ketamine (55 mg/kg) and the alpha(2)-adrenergic receptor agonist xylazine (6 mg/kg) were able to imprint on day 8 after hatching, whereas controls treated with saline did not imprint. We now show that the effect of the ketamine-xylazine mixture can be mimicked by treating chicks with ketamine alone or with another noncompetitive NMDA receptor antagonist, MK-801 (5 mg/kg). Treating chicks with a single dose of ketamine (55 mg/kg) or with a single dose of xylazine (6 mg/kg) failed to produce the effect on the sensitive period. However, prolonging the action of ketamine by treating chicks with two doses of ketamine (at 10 and 12 h after hatching) did allow imprinting on day 8. In contrast, prolonging the action of xylazine had no effect on the sensitive period for imprinting. Chicks treated with MK-801 were also able to imprint on day 8. Thus, we have evidence that the NMDA receptor system is involved in the mechanisms that control the sensitive period for imprinting.

  3. Picrotoxin-induced seizures modified by morphine and opiate antagonists.

    PubMed

    Thomas, J; Nores, W L; Kenigs, V; Olson, G A; Olson, R D

    1993-07-01

    The effects of naloxone, Tyr-MIF-1, and MIF-1 on morphine-mediated changes in susceptibility to picrotoxin-induced seizures were studied. Rats were pretreated with naloxone, MIF-1, Tyr-MIF-1, or saline. At 15-min intervals, they received a second pretreatment of morphine or saline and then were tested for seizures following a convulsant dose of picrotoxin. Several parameters of specific categories of seizures were scored. Morphine increased the number of focal seizure episodes, duration of postseizure akinesis, and incidence of generalized clonic seizures. Naloxone tended to block the morphine-mediated changes in susceptibility. Tyr-MIF-1 had effects similar to naloxone on duration of postseizure immobility but tended to potentiate the effects of morphine on focal seizure episodes. The effects of morphine and the opiate antagonists on focal seizure episodes and postseizure duration suggest the general involvement of several types of opiate receptors in these picrotoxin-induced behaviors. However, the observation of antagonistic effects for Tyr-MIF-1 on immobility but agonistic effects for focal seizures suggests that the type of effect exerted by opiate agents may depend upon other neuronal variables.

  4. Modification of kindled amygdaloid seizures by opiate agonists and antagonists.

    PubMed

    Albertson, T E; Joy, R M; Stark, L G

    1984-03-01

    The effects of 19 opiate agonists and antagonists on kindled amygdaloid seizures in the rat were studied. The mu agonists tended to reduce the length of elicited afterdischarges and behavioral ranks, while markedly increasing postictal electroencephalogram spikes and behavioral arrest time. These effects were reversed by naloxone. The kappa agonists reduced behavioral rank and variably reduced afterdischarge length with a concomitant lengthening of postictal behavioral arrest time and number of electroencephalogram spikes. The putative sigma agonist, SKF 10,047, reduced afterdischarge durations only at the higher doses tested. The decreases found after the sigma agonists in postictal electroencephalogram spiking and time of behavioral arrest were not reversed by naloxone. Only the lower doses of normeperidine were found to decrease seizure thresholds. The mixed agonist/antagonists (MAA) cyclazocine and cyclorphan markedly increased seizure threshold and reduced afterdischarge duration and behavioral rank. Only the MAA pentazocine tended to increase threshold but not suprathreshold afterdischarge durations. The order of ability to modify the ictal events was MAA (selected) greater than kappa agonists greater than mu agonists greater than sigma agonists. The increase in postictal events (behavior arrest and spikes) was caused most effectively by pretreatment with mu agonist greater than kappa agonist greater than selected MAA greater than sigma agonists.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Contrasting effects of intralocus sexual conflict on sexually antagonistic coevolution

    PubMed Central

    Pennell, Tanya M.; de Haas, Freek J. H.; Morrow, Edward H.; van Doorn, G. Sander

    2016-01-01

    Evolutionary conflict between the sexes can induce arms races in which males evolve traits that are detrimental to the fitness of their female partners, and vice versa. This interlocus sexual conflict (IRSC) has been proposed as a cause of perpetual intersexual antagonistic coevolution with wide-ranging evolutionary consequences. However, theory suggests that the scope for perpetual coevolution is limited, if traits involved in IRSC are subject to pleiotropic constraints. Here, we consider a biologically plausible form of pleiotropy that has hitherto been ignored in treatments of IRSC and arrive at drastically different conclusions. Our analysis is based on a quantitative genetic model of sexual conflict, in which genes controlling IRSC traits have side effects in the other sex, due to incompletely sex-limited gene expression. As a result, the genes are exposed to intralocus sexual conflict (IASC), a tug-of-war between opposing male- and female-specific selection pressures. We find that the interaction between the two forms of sexual conflict has contrasting effects on antagonistic coevolution: Pleiotropic constraints stabilize the dynamics of arms races if the mating traits are close to evolutionary equilibrium but can prevent populations from ever reaching such a state. Instead, the sexes are drawn into a continuous cycle of arms races, causing the buildup of IASC, alternated by phases of IASC resolution that trigger the next arms race. These results encourage an integrative perspective on the biology of sexual conflict and generally caution against relying exclusively on equilibrium stability analysis. PMID:26755609

  6. Fires can benefit plants by disrupting antagonistic interactions.

    PubMed

    García, Y; Castellanos, M C; Pausas, J G

    2016-12-01

    Fire has a key role in the ecology and evolution of many ecosystems, yet its effects on plant-insect interactions are poorly understood. Because interacting species are likely to respond to fire differently, disruptions of the interactions are expected. We hypothesized that plants that regenerate after fire can benefit through the disruption of their antagonistic interactions. We expected stronger effects on interactions with specialist predators than with generalists. We studied two interactions between two Mediterranean plants (Ulex parviflorus, Asphodelus ramosus) and their specialist seed predators after large wildfires. In A. ramosus we also studied the generalist herbivores. We sampled the interactions in burned and adjacent unburned areas during 2 years by estimating seed predation, number of herbivores and fruit set. To assess the effect of the distance to unburned vegetation we sampled plots at two distance classes from the fire perimeter. Even 3 years after the fires, Ulex plants experienced lower seed damage by specialists in burned sites. The presence of herbivores on Asphodelus decreased in burned locations, and the variability in their presence was significantly related to fruit set. Generalist herbivores were unaffected. We show that plants can benefit from fire through the disruption of their antagonistic interactions with specialist seed predators for at least a few years. In environments with a long fire history, this effect might be one additional mechanism underlying the success of fire-adapted plants.

  7. Effects of the NMDA antagonist memantine on human methamphetamine discrimination.

    PubMed

    Hart, Carl L; Haney, Margaret; Foltin, Richard W; Fischman, Marian W

    2002-12-01

    The discriminative stimulus effects of N-methyl- D-aspartate (NMDA) antagonists have been assessed in laboratory animals. To date, no published study has assessed their ability to alter methamphetamine-related discriminative stimulus effects in humans. This study investigated the discriminative stimulus, subjective (e.g. "Good Drug Effect"), psychomotor performance, and cardiovascular effects (e.g. blood pressure) of oral methamphetamine following acute oral memantine (a non-competitive NMDA antagonist) in humans. Initially, participants were trained to discriminate 10 mg methamphetamine from placebo using a standard two-response procedure (drug versus placebo). Then, the effects of memantine (0, 40 mg) on methamphetamine discrimination were examined across several methamphetamine doses (0, 5, 10, 20 mg) using a novel-response procedure (drug versus placebo versus novel). Following placebo pretreatment, 10 mg methamphetamine produced 99% methamphetamine-appropriate responding and placebo produced 75% placebo-appropriate responding. Following memantine pretreatment, participants responded as if they had been given a novel compound, although memantine did not significantly alter most subjective-effects ratings following methamphetamine. Memantine alone produced "positive" subjective effects and novel drug-appropriate responding. These data indicate that the memantine-methamphetamine combination produced novel discriminative stimulus effects and that memantine produced some stimulant-like subjective effects.

  8. Potential antipsychotic properties of central cannabinoid (CB1) receptor antagonists.

    PubMed

    Roser, Patrik; Vollenweider, Franz X; Kawohl, Wolfram

    2010-03-01

    Delta(9)-Tetrahydrocannabinol (Delta(9)-THC), the principal psychoactive constituent of the Cannabis sativa plant, and other agonists at the central cannabinoid (CB(1)) receptor may induce characteristic psychomotor effects, psychotic reactions and cognitive impairment resembling schizophrenia. These effects of Delta(9)-THC can be reduced in animal and human models of psychopathology by two exogenous cannabinoids, cannabidiol (CBD) and SR141716. CBD is the second most abundant constituent of Cannabis sativa that has weak partial antagonistic properties at the CB(1) receptor. CBD inhibits the reuptake and hydrolysis of anandamide, the most important endogenous CB(1) receptor agonist, and exhibits neuroprotective antioxidant activity. SR141716 is a potent and selective CB(1) receptor antagonist. Since both CBD and SR141716 can reverse many of the biochemical, physiological and behavioural effects of CB(1) receptor agonists, it has been proposed that both CBD and SR141716 have antipsychotic properties. Various experimental studies in animals, healthy human volunteers, and schizophrenic patients support this notion. Moreover, recent studies suggest that cannabinoids such as CBD and SR141716 have a pharmacological profile similar to that of atypical antipsychotic drugs. In this review, both preclinical and clinical studies investigating the potential antipsychotic effects of both CBD and SR141716 are presented together with the possible underlying mechanisms of action.

  9. Novel quinolinone-phosphonic acid AMPA antagonists devoid of nephrotoxicity.

    PubMed

    Cordi, Alex A; Desos, Patrice; Ruano, Elisabeth; Al-Badri, Hashim; Fugier, Claude; Chapman, Astrid G; Meldrum, Brian S; Thomas, Jean-Yves; Roger, Anita; Lestage, Pierre

    2002-10-01

    We reported previously the synthesis and structure-activity relationships (SAR) in a series of 2-(1H)-oxoquinolines bearing different acidic functions in the 3-position. Exploiting these SAR, we were able to identify 6,7-dichloro-2-(1H)-oxoquinoline-3-phosphonic acid compound 3 (S 17625) as a potent, in vivo active AMPA antagonist. Unfortunately, during the course of the development, nephrotoxicity was manifest at therapeutically effective doses. Considering that some similitude exists between S 17625 and probenecid, a compound known to protect against the nephrotoxicity and/or slow the clearance of different drugs, we decided to synthesise some new analogues of S 17625 incorporating some of the salient features of probenecid. Replacement of the chlorine in position 6 by a sulfonylamine led to very potent AMPA antagonists endowed with good in vivo activity and lacking nephrotoxicity potential. Amongst the compounds evaluated, derivatives 7a and 7s appear to be the most promising and are currently evaluated in therapeutically relevant stroke models.

  10. The 5-HT2A receptor antagonist M100907 is more effective in counteracting NMDA antagonist- than dopamine agonist-induced hyperactivity in mice.

    PubMed

    Carlsson, M L; Martin, P; Nilsson, M; Sorensen, S M; Carlsson, A; Waters, S; Waters, N

    1999-01-01

    The purpose of the present study was to compare the effectiveness of the selective 5-HT2A antagonist M100907 in different psychosis models. The classical neuroleptic haloperidol was used as reference compound. Two hyperdopaminergia and two hypoglutamatergia mouse models were used. Hyperdopaminergia was produced by the DA releaser d-amphetamine or the DA uptake inhibitor GBR 12909. Hypoglutamatergia was produced by the un-competitive NMDA receptor antagonist MK-801 or the competitive NMDA receptor antagonist D-CPPene. M100907 was found to counteract the locomotor stimulant effects of the NMDA receptor antagonists MK-801 and D-CPPene, but spontaneous locomotion, d-amphetamine- and GBR-12909-induced hyperactivity were not significantly affected. Haloperidol, on the other hand, antagonized both NMDA antagonist- and DA agonist-induced hyperactivity, as well as spontaneous locomotion in the highest dose used. Based on the present and previous results we draw the conclusion that 5-HT2A receptor antagonists are particularly effective against behavioural anomalies resulting from hypoglutamatergia of various origins. The clinical implications of our results and conclusions would be that a 5-HT2A receptor antagonist, due to i a the low side effect liability, could be the preferable treatment strategy in various disorders associated with hypoglutamatergia; such conditions might include schizophrenia, childhood autism and dementia disorders.

  11. Functionalized Congeners of P2Y1 Receptor Antagonists:

    SciTech Connect

    de Castro, Sonia; Maruoka, Hiroshi; Hong, Kunlun

    2010-01-01

    The P2Y{sub 1} receptor is a prothrombotic G protein-coupled receptor (GPCR) activated by ADP. Preference for the North (N) ring conformation of the ribose moiety of adenine nucleotide 3',5'-bisphosphate antagonists of the P2Y{sub 1} receptor was established by using a ring-constrained methanocarba (a bicyclo[3.1.0]hexane) ring as a ribose substitute. A series of covalently linkable N{sup 6}-methyl-(N)-methanocarba-2'-deoxyadenosine-3',5'-bisphosphates containing extended 2-alkynyl chains was designed, and binding affinity at the human (h) P2Y{sub 1} receptor determined. The chain of these functionalized congeners contained hydrophilic moieties, a reactive substituent, or biotin, linked via an amide. Variation of the chain length and position of anmore » intermediate amide group revealed high affinity of carboxylic congener 8 (K{sub i} 23 nM) and extended amine congener 15 (K{sub i} 132 nM), both having a 2-(1-pentynoyl) group. A biotin conjugate 18 containing an extended {epsilon}-aminocaproyl spacer chain exhibited higher affinity than a shorter biotinylated analogue. Alternatively, click coupling of terminal alkynes of homologous 2-dialkynyl nucleotide derivatives to alkyl azido groups produced triazole derivatives that bound to the P2Y{sub 1} receptor following deprotection of the bisphosphate groups. The preservation of receptor affinity of the functionalized congeners was consistent with new P2Y{sub 1} receptor modeling and ligand docking. Attempted P2Y{sub 1} antagonist conjugation to PAMAM dendrimer carriers by amide formation or palladium-catalyzed reaction between an alkyne on the dendrimer and a 2-iodopurine-derivatized nucleotide was unsuccessful. A dialkynyl intermediate containing the chain length favored in receptor binding was conjugated to an azide-derivatized dendrimer, and the conjugate inhibited ADP-promoted human platelet aggregation. This is the first example of attaching a strategically functionalized P2Y receptor antagonist to a PAMAM

  12. MEN15596, a novel nonpeptide tachykinin NK2 receptor antagonist.

    PubMed

    Cialdai, Cecilia; Tramontana, Manuela; Patacchini, Riccardo; Lecci, Alessandro; Catalani, Claudio; Catalioto, Rose-Marie; Meini, Stefania; Valenti, Claudio; Altamura, Maria; Giuliani, Sandro; Maggi, Carlo Alberto

    2006-11-07

    The pharmacological profile of MEN15596 or (6-methyl-benzo[b]thiophene-2-carboxylic acid [1-(2-phenyl-1R-{[1-(tetrahydropyran-4-ylmethyl)-piperidin-4-ylmethyl]-carbamoyl}-ethylcarbamoyl)-cyclopentyl]-amide), a novel potent and selective tachykinin NK2 receptor antagonist endowed with oral activity, is described. At the human recombinant tachykinin NK2 receptor, MEN15596 showed subnanomolar affinity (pKi 10.1) and potently antagonized (pKB 9.1) the neurokinin A-induced intracellular calcium release. MEN15596 selectivity for the tachykinin NK2 receptor was assessed by binding studies at the recombinant tachykinin NK1 (pKi 6.1) and NK3 (pKi 6.4) receptors, and at a number of 34 molecular targets including receptors, transporters and ion channels. In isolated smooth muscle preparations MEN15596 showed a marked species selectivity at the tachykinin NK2 receptor with the highest antagonist potency in guinea-pig colon, human and pig bladder (pKB 9.3, 9.2 and 8.8, respectively) whereas it was three orders of magnitude less potent in the rat and mouse urinary bladder (pKB 6.3 and 5.8, respectively). In agreement with binding experiments, MEN15596 showed low potency in blocking selective NK1 or NK3 receptor agonist-induced contractions of guinea-pig ileum preparations (pA2

  13. Drug safety is a barrier to the discovery and development of new androgen receptor antagonists.

    PubMed

    Foster, William R; Car, Bruce D; Shi, Hong; Levesque, Paul C; Obermeier, Mary T; Gan, Jinping; Arezzo, Joseph C; Powlin, Stephanie S; Dinchuk, Joseph E; Balog, Aaron; Salvati, Mark E; Attar, Ricardo M; Gottardis, Marco M

    2011-04-01

    Androgen receptor (AR) antagonists are part of the standard of care for prostate cancer. Despite the almost inevitable development of resistance in prostate tumors to AR antagonists, no new AR antagonists have been approved for over a decade. Treatment failure is due in part to mutations that increase activity of AR in response to lower ligand concentrations as well as to mutations that result in AR response to a broader range of ligands. The failure to discover new AR antagonists has occurred in the face of continued research; to enable progress, a clear understanding of the reasons for failure is required. Non-clinical drug safety studies and safety pharmacology assays were performed on previously approved AR antagonists (bicalutamide, flutamide, nilutamide), next generation antagonists in clinical testing (MDV3100, BMS-641988), and a pre-clinical drug candidate (BMS-501949). In addition, non-clinical studies with AR mutant mice, and EEG recordings in rats were performed. Non-clinical findings are compared to disclosures of clinical trial results. As a drug class, AR antagonists cause seizure in animals by an off-target mechanism and are found in vitro to inhibit GABA-A currents. Clinical trials of candidate next generation AR antagonists identify seizure as a clinical safety risk. Non-clinical drug safety profiles of the AR antagonist drug class create a significant barrier to the identification of next generation AR antagonists. GABA-A inhibition is a common off-target activity of approved and next generation AR antagonists potentially explaining some side effects and safety hazards of this class of drugs. Copyright © 2010 Wiley-Liss, Inc.

  14. Antibacterial, antifungal, antispasmodic and Ca++ antagonist effects of Caesalpinia bonducella.

    PubMed

    Khan, Hidayat-Ullah; Ali, Irshad; Khan, Arif-Ullah; Naz, Rubina; Gilani, Anwarul Hassan

    2011-02-01

    Caesalpinia bonducella F. (Leguminosae) has been used as a folk medicine for a variety of ailments. The crude extract of C. bonducella and its fractions were studied for antibacterial, antifungal, antispasmodic and Ca++ antagonistic properties. The strongest antibacterial effect was displayed by the n-butanol (72%) and ethyl acetate (80%) fractions, followed by the crude extract (46% and 42%), against Escherichia coli and Bacillus subtilis, respectively. The plant extract and its fractions showed mild to excellent activity in antifungal bioassays, with maximum antifungal activity against Candida glaberata (80%) and Aspergillus flavus (70%) by the n-butanol and chloroform fractions, followed by the crude extract (70% and 65%). Caesalpinia bonducella extract caused concentration-dependent inhibition of spontaneous and high K+ (80 mM)-induced contractions of isolated rabbit jejunum preparations, similar to that caused by Verapamil. These results indicate that C. bonducella exhibits antibacterial, antifungal, spasmolytic and Ca++ channel blocking actions.

  15. Vitamin K antagonists and direct thrombin inhibitors: present and future.

    PubMed

    Pineo, Graham F; Hull, Russell D

    2005-02-01

    Warfarin and related compounds are efficacious and safe in a variety of clinical thrombotic disorders; however, these drugs have a narrow therapeutic window, whereby inadequate therapy is associated with an increased thrombotic risk and overanticoagulation is associated with bleeding. Therefore, attempts have been made to develop alternatives to warfarin. Ximelagatran, an oral direct thrombin inhibitor, has been shown to be as efficacious and safe as warfarin for the prevention and treatment of different thrombotic disorders. This article reviews the pharmacology of the coumarins, the most commonly used vitamin K antagonists, and the practical aspects regarding their use in the management of thrombotic disorders. The future role of the oral direct thrombin inhibitor ximelagatran also is reviewed.

  16. Managing resistant hypertension: focus on mineralocorticoid-receptor antagonists

    PubMed Central

    Yugar-Toledo, Juan Carlos; Modolo, Rodrigo; de Faria, Ana Paula; Moreno, Heitor

    2017-01-01

    Mineralocorticoid-receptor antagonists (MRAs) have proven to be effective in some types of hypertension, especially in resistant hypertension (RHTN). In this phenotype of hypertension, the renin–angiotensin–aldosterone pathway plays an important role, with MRAs being especially effective in reducing blood pressure. In this review, we show the relevance of aldosterone in RHTN, as well as some clinical characteristics of this condition and the main concepts involving its pathophysiology and cardiovascular damage. We analyzed the mechanisms of action and clinical effects of two current MRAs – spironolactone and eplerenone – both of which are useful in RHTN, with special attention to the former. RHTN represents a significant minority (10%–15%) of hypertension cases. However, primary-care physicians, cardiologists, nephrologists, neurologists, and geriatricians face this health problem on a daily basis. MRAs are likely one of the best pharmacological options in RHTN patients; however, they are still underused. PMID:29081661

  17. TNF-alpha antagonist induced lupus on three different agents.

    PubMed

    Mudduluru, Bindu Madhavi; Shah, Shalin; Shamah, Steven; Swaminath, Arun

    2017-03-01

    Tumor necrosis factor alpha (TNF alpha) antagonists are biologic agents used in the management of inflammatory conditions such as rheumatoid arthritis, seronegative spondyloarthropathies and inflammatory bowel disease. These agents have been recently shown to cause a syndrome called anti-TNF induced lupus (ATIL), a rare condition which has similar clinical manifestations to idiopathic systemic lupus erythematosus (SLE). Given that extra-intestinal manifestations of inflammatory bowel disease include arthritis, it can be difficult to separate arthritis due to underlying disease from drug-induced arthritis. We present a case of a 28-year-old female with Crohn's disease, who developed disabling arthritis as a clinical manifestation of ATIL following treatment with three anti-TNF agents, namely infliximab, adalimumab and certolizumab.

  18. Comparative trial of serotonin antagonists in the management of migraine.

    PubMed

    Lance, J W; Anthony, M; Somerville, B

    1970-05-09

    The effectiveness of five different serotonin antagonists in the prevention of migraine was compared in 290 patients followed for periods of up to three years. Methysergide 3-6 mg. daily was most effective, with 20% of treated patients becoming headache-free and a further 44% remaining more than "half improved." The corresponding figures for BC105 were 10% and 40%, respectively.The results with BC105 were significantly better than those with placebo (P<0.02). The total improvement rates with methdilazine (45%) and cyproheptadine (43%) were better than those with placebo (32%) but did not achieve statistical significance. A new preparation, methylergol carbamide maleate, which is chemically related to methysergide, did not give better results than placebo.

  19. Rational use of calcium-channel antagonists in Raynaud's phenomenon.

    PubMed

    Sturgill, M G; Seibold, J R

    1998-11-01

    Raynaud's phenomenon (RP) is a peripheral circulatory disorder characterized by sudden episodes of digital artery spasm, often precipitated by cold temperature or emotional stress. Although the cause of RP is not fully known, it appears to involve inappropriate adrenergic response to cold stimuli. Treatment of RP is conservative in most patients, but in patients with severe disease includes the use of agents that promote digital vasodilation. The calcium-channel antagonists, particularly the dihydropyridine derivative nifedipine, are the most thoroughly studied drug class for the treatment of RP. Approximately two thirds of patients respond favorably, with significant reductions in the frequency and severity of vasospastic attacks. Nifedipine use is often limited by the appearance of adverse vasodilatory effects such as headache or peripheral edema. The newer second-generation dihydropyridines such as amlodipine, isradipine, nicardipine, and felodipine also appear to be effective in patients with RP and may be associated with fewer adverse effects.

  20. Aptamer antagonists of myelin-derived inhibitors promote axon growth.

    PubMed

    Wang, Yuxuan; Khaing, Zin Z; Li, Na; Hall, Brad; Schmidt, Christine E; Ellington, Andrew D

    2010-03-16

    Myelin of the adult central nervous system (CNS) is one of the major sources of inhibitors of axon regeneration following injury. The three known myelin-derived inhibitors (Nogo, MAG, and OMgp) bind with high affinity to the Nogo-66 receptor (NgR) on axons and limit neurite outgrowth. Here we show that RNA aptamers can be generated that bind with high affinity to NgR, compete with myelin-derived inhibitors for binding to NgR, and promote axon elongation of neurons in vitro even in the presence of these inhibitors. Aptamers may have key advantages over protein antagonists, including low immunogenicity and the possibility of ready modification during chemical synthesis for stability, signaling, or immobilization. This first demonstration that aptamers can directly influence neuronal function suggests that aptamers may prove useful for not only healing spinal cord and other neuronal damage, but may be more generally useful as neuromodulators.

  1. Aptamer Antagonists of Myelin-Derived Inhibitors Promote Axon Growth

    PubMed Central

    Wang, Yuxuan; Khaing, Zin Z.; Li, Na; Hall, Brad; Schmidt, Christine E.; Ellington, Andrew D.

    2010-01-01

    Myelin of the adult central nervous system (CNS) is one of the major sources of inhibitors of axon regeneration following injury. The three known myelin-derived inhibitors (Nogo, MAG, and OMgp) bind with high affinity to the Nogo-66 receptor (NgR) on axons and limit neurite outgrowth. Here we show that RNA aptamers can be generated that bind with high affinity to NgR, compete with myelin-derived inhibitors for binding to NgR, and promote axon elongation of neurons in vitro even in the presence of these inhibitors. Aptamers may have key advantages over protein antagonists, including low immunogenicity and the possibility of ready modification during chemical synthesis for stability, signaling, or immobilization. This first demonstration that aptamers can directly influence neuronal function suggests that aptamers may prove useful for not only healing spinal cord and other neuronal damage, but may be more generally useful as neuromodulators. PMID:20300533

  2. Effect of diseases on response to vitamin K antagonists.

    PubMed

    Self, Timothy H; Owens, Ryan E; Sakaan, Sami A; Wallace, Jessica L; Sands, Christopher W; Howard-Thompson, Amanda

    2016-01-01

    The purpose of this review article is to summarize the literature on diseases that are documented to have an effect on response to warfarin and other VKAs. We searched the English literature from 1946 to September 2015 via PubMed, EMBASE, and Scopus for the effect of diseases on response vitamin K antagonists including warfarin, acenocoumarol, phenprocoumon, and fluindione. Among many factors modifying response to VKAs, several disease states are clinically relevant. Liver disease, hyperthyroidism, and CKD are well documented to increase response to VKAs. Decompensated heart failure, fever, and diarrhea may also elevate response to VKAs, but more study is needed. Hypothyroidism is associated with decreased effect of VKAs, and obese patients will likely require higher initial doses of VKAs. In order to minimize risks with VKAs while ensuring efficacy, clinicians must be aware of the effect of disease states when prescribing these oral anticoagulants.

  3. High-Throughput Screening of Small Molecules Identifies Hepcidin Antagonists

    PubMed Central

    Fung, Eileen; Sugianto, Priscilla; Hsu, Jason; Damoiseaux, Robert; Ganz, Tomas

    2013-01-01

    Anemia of inflammation (AI) is common in patients with infection, autoimmune diseases, cancer, and chronic kidney disease. Unless the underlying condition can be reversed, treatment options are limited to erythropoiesis-stimulating agents with or without intravenous iron therapy, modalities that are not always effective and can cause serious adverse effects. Hepcidin, the iron regulatory hormone, has been identified as a pathogenic factor in the development of AI. To explore new therapeutic options for AI and other iron-related disorders caused by hepcidin excess, we developed a cell-based screen to identify hepcidin antagonists. Of the 70,000 small molecules in the library, we identified 14 compounds that antagonized the hepcidin effect on ferroportin. One of these was fursultiamine, a Food and Drug Administration (FDA)–approved thiamine derivative. Fursultiamine directly interfered with hepcidin binding to its receptor, ferroportin, by blocking ferroportin C326 thiol residue essential for hepcidin binding. Consequently, fursultiamine prevented hepcidin-induced ferroportin ubiquitination, endocytosis, and degradation in vitro and allowed continuous cellular iron export despite the presence of hepcidin, with IC50 in the submicromolar range. Thiamine, the fursultiamine metabolite, and benfotiamine, another thiamine derivative, did not interfere with the effect of hepcidin on ferroportin. Other FDA-approved thiol-reactive compounds were at least 1000-fold less potent than fursultiamine in antagonizing hepcidin. In vivo, fursultiamine did not reproducibly antagonize the effect of hepcidin on serum iron, likely because of its rapid conversion to inactive metabolites. Fursultiamine is a unique antagonist of hepcidin in vitro that could serve as a template for the development of drug candidates that inhibit the hepcidin-ferroportin interaction. PMID:23292796

  4. Concentric agonist-antagonist robots for minimally invasive surgeries

    NASA Astrophysics Data System (ADS)

    Oliver-Butler, Kaitlin; Epps, Zane H.; Rucker, Daniel Caleb

    2017-03-01

    We present a novel continuum robot design concept, Concentric Agonist-Antagonist Robots (CAAR), that uses push-pull, agonist-antagonist action of a pair of concentric tubes. The CAAR tubes are designed to have noncentral, offset neutral axes, and they are fixed together at their distal ends. Axial base translations then induce bending in the device. A CAAR segment can be created by selectively cutting asymmetric notches into the profile of two stock tubes, which relocates the neutral bending plane away from the center of the inner lumen. Like conventional concentric-tube robots (CTRs) based on counter-rotating precurved tubes, a CAAR can be made at very small scales and contain a large, open lumen. In contrast with CTRs, the CAAR concept has no elastic stability issues, offers a larger range of motion, and has lower overall stiffness. Furthermore, by varying the position of the neutral axes along the length of each tube, arbitrary, variable curvature actuation modes can be achieved. Precurving the tubes can additionally increase the workspace of a single segment. A single two-tube assembly can be used to create 3 degree-of-freedom (DOF) robot segments, and multiple segments can be deployed concentrically. Both additive manufacturing and traditional machining of stock tubes can create and customize the geometry and performance of the CAAR. In this paper, we explore the CAAR concept, provide kinematic and static models, and experimentally evaluate the model with a both a straight and a precurved CAAR. We conclude with a discussion of the significance and our plans for future work.

  5. Comparison of GnRH agonist, GnRH antagonist, and GnRH antagonist mild protocol of controlled ovarian hyperstimulation in good prognosis patients.

    PubMed

    Stimpfel, Martin; Vrtacnik-Bokal, Eda; Pozlep, Barbara; Virant-Klun, Irma

    2015-01-01

    The reports on how to stimulate the ovaries for oocyte retrieval in good prognosis patients are contradictory and often favor one type of controlled ovarian hyperstimulation (COH). For this reason, we retrospectively analyzed data from IVF/ICSI cycles carried out at our IVF Unit in good prognosis patients (aged <38 years, first and second attempts of IVF/ICSI, more than 3 oocytes retrieved) to elucidate which type of COH is optimal at our condition. The included patients were undergoing COH using GnRH agonist, GnRH antagonist or GnRH antagonist mild protocol in combination with gonadotrophins. We found significant differences in the average number of retrieved oocytes, immature oocytes, fertilized oocytes, embryos, transferred embryos, embryos frozen per cycle, and cycles with embryo freezing between studied COH protocols. Although there were no differences in live birth rate (LBR), miscarriages, and ectopic pregnancies between compared protocols, pregnancy rate was significantly higher in GnRH antagonist mild protocol in comparison with both GnRH antagonist and GnRH agonist protocols and cumulative LBR per cycle was significantly higher in GnRH antagonist mild protocol in comparison to GnRH agonist protocol. Our data show that GnRH antagonist mild protocol of COH could be the best method of choice in good prognosis patients.

  6. Benzimidazoles as benzamide replacements within cyclohexane-based CC chemokine receptor 2 (CCR2) antagonists.

    PubMed

    Cherney, Robert J; Mo, Ruowei; Meyer, Dayton T; Pechulis, Anthony D; Guaciaro, Michael A; Lo, Yvonne C; Yang, Gengjie; Miller, Persymphonie B; Scherle, Peggy A; Zhao, Qihong; Cvijic, Mary Ellen; Barrish, Joel C; Decicco, Carl P; Carter, Percy H

    2012-10-01

    We describe the design, synthesis, and evaluation of benzimidazoles as benzamide replacements within a series of trisubstituted cyclohexane CCR2 antagonists. 7-Trifluoromethylbenzimidazoles displayed potent binding and functional antagonism of CCR2 while being selective over CCR3. These benzimidazoles were also incorporated into lactam-containing antagonists, thus completely eliminating the customary bis-amide. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Discovery of spiropiperidine-based potent and selective Orexin-2 receptor antagonists.

    PubMed

    Fujimoto, Tatsuhiko; Tomata, Yoshihide; Kunitomo, Jun; Hirozane, Mariko; Marui, Shogo

    2011-11-01

    To generate novel human Orexin-2 Receptor (OX2R) antagonists, a spiropiperidine based scaffold was designed and a SAR study was carried out. Compound 4f possessed the highest OX2R antagonistic activity with an IC(50) value of 3nM with 450-fold selectivity against Orexin-1 Receptor (OX1R). Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Controversial therapeutics: the β-adrenergic antagonist and cocaine-associated cardiovascular complications dilemma.

    PubMed

    Schurr, James W; Gitman, Brenda; Belchikov, Yuly

    2014-12-01

    Cocaine abuse is associated with cardiovascular complications that include chest pain and myocardial infarction. Traditional therapy for these conditions includes a β-adrenergic antagonist. However, guidelines released in 2008 recommended against this treatment option because of the prevailing theory that cocaine will potentiate vasospasm secondary to unopposed α-adrenergic effects. Subsequently, further evidence and updated guidelines have become available, debunking this claim. Current literature is limited but suggests that β-adrenergic antagonists are harmful. Although case reports support a detrimental effect of β-adrenergic antagonists, the anecdotal data are inconsistent, and the conclusions from case studies are overruled by larger studies. The pharmacology, pathophysiology, and literature on the use of β-adrenergic antagonists in association with cocaine are reviewed. Future studies that focus on outcomes and different pharmacologic profiles of β-adrenergic antagonists are needed. © 2014 Pharmacotherapy Publications, Inc.

  9. Permanent renal loss following tumor necrosis factor α antagonists for arthritis.

    PubMed

    Chen, Tzu-Jen; Yang, Ya-Fei; Huang, Po-Hao; Lin, Hsin-Hung; Huang, Chiu-Ching

    2010-06-01

    Tumor necrosis factor alpha (TNF-alpha) antagonists are now widely used in the treatment of aggressive rheumatoid arthritis and are generally well tolerated. Although rare, they could induce systemic lupus erythematosus, glomerulonephritis, and antineutrophil cytoplasmic antibody associated systemic vasculitis. Tumor necrosis factor alpha antagonists associated glomerulonephritis usually subsides after discontinuation of the therapy and subsequent initiation of corticosteroids and immunosuppressive agents. Here we describe crescentic glomerulonephritis progression to end-stage renal disease in a patient following two doses of TNF-alpha antagonists for the treatment of reactive arthritis. To our knowledge, dialysis dependent permanent renal loss after TNF-alpha antagonists has not yet been reported. We suggest the renal function should be closely monitored in patients treated with TNF-alpha antagonists by rheumatologists.

  10. Screening of antagonistic bacteria for biological control of nursery wilt of black pepper (Piper nigrum).

    PubMed

    Anith, K N; Radhakrishnan, N V; Manomohandas, T P

    2003-01-01

    Bacterial antagonists of Phytophthora capsici were isolated from underground shoot portions of rooted cuttings of black pepper. Initially isolates were screened by dual culture on potato dextrose agar and carrot agar. Further, a screening was done on black pepper shoots for supression of lesion caused by the pathogen. Most of the antagonists showed varying levels of antagonism in the dual culture and the shoot assay. Isolate PN-026, showing the highest suppression of lesion development in the shoot assay was found to be the most efficient antagonist in reducing Phytophthora capsici induced nursery wilt of black pepper. This screening involving the host, pathogen, and the antagonist, performed on black pepper shoot (the planting material for this vegetatively propagated crop), could be used as a rapid and reliable method for the isolation of efficient bacterial antagonists of P. capsici.

  11. σ Receptor antagonist attenuation of methamphetamine-induced neurotoxicity is correlated to body temperature modulation.

    PubMed

    Robson, Matthew J; Seminerio, Michael J; McCurdy, Christopher R; Coop, Andrew; Matsumoto, Rae R

    2013-01-01

    Methamphetamine (METH) causes hyperthermia and dopaminergic neurotoxicity in the rodent striatum. METH interacts with σ receptors and σ receptor antagonists normally mitigate METH-induced hyperthermia and dopaminergic neurotoxicity. The present study was undertaken because in two experiments, pretreatment with σ receptor antagonists failed to attenuate METH-induced hyperthermia in mice. This allowed us to determine whether the ability of σ receptor antagonists (AZ66 and AC927) to mitigate METH-induced neurotoxicity depends upon their ability to modulate METH-induced hyperthermia. Mice were treated using a repeated dosing paradigm and body temperatures recorded. Striatal dopamine was measured one week post-treatment. The data indicate that the ability of σ receptor antagonists to attenuate METH-induced dopaminergic neurotoxicity is linked to their ability to block METH-induced hyperthermia. The ability of σ receptor antagonists to mitigate METH-induced hyperthermia may contribute to its neuroprotective actions.

  12. Comparative Effectiveness of Renin-Angiotensin System Antagonists in Maintenance Dialysis Patients

    PubMed Central

    Shireman, Theresa I.; Mahnken, Jonathan D.; Phadnis, Milind A.; Ellerbeck, Edward F.; Wetmore, James B.

    2017-01-01

    Background/Aims Whether angiotensin converting enzyme inhibitors (ACE) and angiotensin receptor blockers (ARB) are differentially associated with reductions in cardiovascular events and mortality in patients receiving maintenance dialysis is uncertain. We compared outcomes between ACE and ARB users among hypertensive, maintenance dialysis patients. Methods National retrospective cohort study of hypertensive, Medicare-Medicaid eligible patients initiating chronic dialysis between 1/1/2000 to 12/31/2005. The exposure of interest was new use of either an ACEI or ARB. Outcomes were all-cause mortality (ACM) and combined cardiovascular hospitalization or death (CV-endpoint). Cox proportion hazards models were used to compare the effect of ACEI vs ARB use on ACM and, separately, CV-endpoint. Results ACM models were based on 3,555 ACEI and 1,442 ARB new users, while CV-endpoint models included 3,289 ACEI and 1,346 ARB new users. After statistical adjustments, ACEI users had higher hazard ratios for ACM (AHR = 1.22, 99% CI 1.05–1.42) and CV-endpoint (AHR = 1.12, 99% CI 0.99–1.27). Conclusions Patients initiating maintenance dialysis who received an ACEI faced an increased risk for mortality and a trend towards an increased risk for CV-endpoints when compared to patients who received an ARB. Validation of these results in a rigorous clinical trial is warranted. PMID:27871075

  13. Comparative Effectiveness of Renin-Angiotensin System Antagonists in Maintenance Dialysis Patients.

    PubMed

    Shireman, Theresa I; Mahnken, Jonathan D; Phadnis, Milind A; Ellerbeck, Edward F; Wetmore, James B

    2016-01-01

    Whether angiotensin converting enzyme inhibitors (ACE) and angiotensin receptor blockers (ARB) are differentially associated with reductions in cardiovascular events and mortality in patients receiving maintenance dialysis is uncertain. We compared outcomes between ACE and ARB users among hypertensive, maintenance dialysis patients. National retrospective cohort study of hypertensive, Medicare-Medicaid eligible patients initiating chronic dialysis between 1/1/2000 to 12/31/2005. The exposure of interest was new use of either an ACEI or ARB. Outcomes were all-cause mortality (ACM) and combined cardiovascular hospitalization or death (CV-endpoint). Cox proportion hazards models were used to compare the effect of ACEI vs ARB use on ACM and, separately, CV-endpoint. ACM models were based on 3,555 ACEI and 1,442 ARB new users, while CV-endpoint models included 3,289 ACEI and 1,346 ARB new users. After statistical adjustments, ACEI users had higher hazard ratios for ACM (AHR = 1.22, 99% CI 1.05-1.42) and CV-endpoint (AHR = 1.12, 99% CI 0.99-1.27). Patients initiating maintenance dialysis who received an ACEI faced an increased risk for mortality and a trend towards an increased risk for CV-endpoints when compared to patients who received an ARB. Validation of these results in a rigorous clinical trial is warranted. © 2016 The Author(s) Published by S. Karger AG, Basel.

  14. Comparative effectiveness of switching to alternative tumour necrosis factor (TNF) antagonists versus switching to rituximab in patients with rheumatoid arthritis who failed previous TNF antagonists: the MIRAR Study.

    PubMed

    Gomez-Reino, Juan J; Maneiro, Jose Ramon; Ruiz, Jorge; Roselló, Rosa; Sanmarti, Raimon; Romero, Ana Belen

    2012-11-01

    To compare the effectiveness of switching to rituximab (RTX) with switching to alternative tumour necrosis factor (TNF) antagonists in patients with rheumatoid arthritis (RA) failing on TNF antagonists. A multicentre prospective 3-year observational study was performed in patients with RA treated with RTX or an alternative TNF antagonist. The baseline 28-joint disease activity score (DAS28) and Health Assessment Questionnaire (HAQ) score were compared with 6, 9 and 12 month values, adjusting for propensity score quintiles. Propensity scores were estimated for each patient using logistic regression with treatment as the dependent variable and baseline prior number of TNFs >1, years from diagnosis >5, extra-articular manifestations, previous toxicity, use of ≥2 disease-modifying antirheumatic drugs, age and sex as independent variables. 1124 patients were treated with either RTX (n=591, 52.6%) or alternative TNF antagonists (n=533, 47.4%). RTX-treated patients had longer disease duration (p=0.0001), larger numbers of previous TNF antagonists (p<0.0001) and tender and swollen joints (p<0.0001). There was no significant difference in the reduction in DAS28 at 6, 9 and 12 months between RTX-treated patients and those treated with TNF antagonists. However, the reduction in DAS28 was significantly different between RTX-treated patients and adalimumab/infliximab-treated patients (p=0.001 and p=0.05, respectively). There was a marginally significant difference at any time period in the proportion of patients achieving an improvement in the HAQ score of >0.22 (p=0.06). Optimal treatment for patients with RA failing on treatment with TNF antagonists may include RTX. This study suggests that the improvement in DAS28 is larger in patients treated with RTX than in those treated with monoclonal anti-TNF agents.

  15. Antagonistic studies and hyphal interactions of the new antagonist Aspergillus piperis against some phytopathogenic fungi in vitro in comparison with Trichoderma harzianum.

    PubMed

    El-Debaiky, Samah A

    2017-12-01

    The present study represents, for the first time, the detailed studies about the hyphal interactions of Aspergillus piperis, as a new antagonist, against some isolated plant pathogenic fungi (Alternaria alternata, Alternaria solani, Botrytis cinerea, Sclerotium cepivorum and Sclerotinia sclerotiorum) in vitro. The bio-controlling capability of A. piperis against the tested phytopathogens was tested using the dual culture method. This experiment revealed that A. piperis had antagonistic activity and reduced the growth of the tested phytopathogens and grew over their mycelia in the paired plates. Also, several antagonistic mechanisms were recorded, in this study, between A. piperis and the tested phytopathogens using the microscopic examination. The bio-controlling activity and the antagonistic mechanisms exhibited by the new antagonist, A. piperis were compared with those obtained by the common antagonist, Trichoderma harzianum against the same phytopathogens. The obtained results showed that, A. piperis was more effective than T. harzianum in inhibiting all the tested species in the dual culture plates. The best result was 81.85% inhibition percentage against S. sclerotiorum by A. piperis while, T. harzianum exhibits only 45.18%. Moreover, several antagonistic mechanisms and hyphal interactions were investigated among the hyphae of both A.piperis and T. harzianum and the hyphae of the tested phytopathogens. These mechanisms were summarized as; mycoparasitism (coiling and penetration of the hyphae) and antibiosis in the form of lysis of the hyphal cells and spores, denaturation and breaking of the hyphae. The indirect interaction (antibiosis) and the direct mycoparasitism were observed by A. piperis against all the tested phytopathogens, but it attacked the hyphae and conidiophores of A. alternata by only the antibiosis interaction. The microscopic examination revealed also that T. harzianum attacked the tested phytopathogens by both antibiosis and mycoparasitism

  16. The NK1 Receptor Antagonist L822429 Reduces Heroin Reinforcement

    PubMed Central

    Barbier, Estelle; Vendruscolo, Leandro F; Schlosburg, Joel E; Edwards, Scott; Juergens, Nathan; Park, Paula E; Misra, Kaushik K; Cheng, Kejun; Rice, Kenner C; Schank, Jesse; Schulteis, Gery; Koob, George F; Heilig, Markus

    2013-01-01

    Genetic deletion of the neurokinin 1 receptor (NK1R) has been shown to decrease the reinforcing properties of opioids, but it is unknown whether pharmacological NK1R blockade has the same effect. Here, we examined the effect of L822429, a rat-specific NK1R antagonist, on the reinforcing properties of heroin in rats on short (1 h: ShA) or long (12 h: LgA) access to intravenous heroin self-administration. ShA produces heroin self-administration rates that are stable over time, whereas LgA leads to an escalation of heroin intake thought to model important dependence-related aspects of addiction. L822429 reduced heroin self-administration and the motivation to consume heroin, measured using a progressive-ratio schedule, in both ShA and LgA rats. L822429 also decreased anxiety-like behavior in both groups, measured on the elevated plus maze, but did not affect mechanical hypersensitivity observed in LgA rats. Expression of TacR1 (the gene encoding NK1R) was decreased in reward- and stress-related brain areas both in ShA and LgA rats compared with heroin-naïve rats, but did not differ between the two heroin-experienced groups. In contrast, passive exposure to heroin produced increases in TacR1 expression in the prefrontal cortex and nucleus accumbens. Taken together, these results show that pharmacological NK1R blockade attenuates heroin reinforcement. The observation that animals with ShA and LgA to heroin were similarly affected by L822429 indicates that the SP/NK1R system is not specifically involved in neuroadaptations that underlie escalation resulting from LgA self-administration. Instead, the NK1R antagonist appears to attenuate acute, positively reinforcing properties of heroin and may be useful as an adjunct to relapse prevention in detoxified opioid-dependent subjects. PMID:23303056

  17. Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists

    PubMed Central

    Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

    2016-01-01

    Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%–80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H3 receptors (H3Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H3Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the (S)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide (1). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R-enantiomer, namely, (R)-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide (2) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S-enantiomer (1), the results show that animals pretreated intraperitoneally (ip) with the R-enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier (R)-enantiomer (3), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its (S)-enantiomer (4) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the (R)-enantiomer (3) in MES model were significantly greater than those of the standard H3R inverse agonist/antagonist pitolisant, comparable with those observed for PHT, and

  18. Anticonvulsant effects of isomeric nonimidazole histamine H3 receptor antagonists.

    PubMed

    Sadek, Bassem; Saad, Ali; Schwed, Johannes Stephan; Weizel, Lilia; Walter, Miriam; Stark, Holger

    2016-01-01

    Phenytoin (PHT), valproic acid, and modern antiepileptic drugs (AEDs), eg, remacemide, loreclezole, and safinamide, are only effective within a maximum of 70%-80% of epileptic patients, and in many cases the clinical use of AEDs is restricted by their side effects. Therefore, a continuous need remains to discover innovative chemical entities for the development of active and safer AEDs. Ligands targeting central histamine H 3 receptors (H 3 Rs) for epilepsy might be a promising therapeutic approach. To determine the potential of H 3 Rs ligands as new AEDs, we recently reported that no anticonvulsant effects were observed for the ( S )-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propanamide ( 1 ). In continuation of our research, we asked whether anticonvulsant differences in activities will be observed for its R -enantiomer, namely, ( R )-2-(4-(3-(piperidin-1-yl)propoxy)benzylamino)propaneamide ( 2 ) and analogs thereof, in maximum electroshock (MES)-, pentylenetetrazole (PTZ)-, and strychnine (STR)-induced convulsion models in rats having PHT and valproic acid (VPA) as reference AEDs. Unlike the S -enantiomer ( 1 ), the results show that animals pretreated intraperitoneally (ip) with the R -enantiomer 2 (10 mg/kg) were moderately protected in MES and STR induced models, whereas proconvulsant effect was observed for the same ligand in PTZ-induced convulsion models. However, animals pretreated with intraperitoneal doses of 5, 10, or 15 mg/kg of structurally bulkier ( R )-enantiomer ( 3 ), in which 3-piperidinopropan-1-ol in ligand 2 was replaced by (4-(3-(piperidin-1-yl)propoxy)phenyl)methanol, and its ( S )-enantiomer ( 4 ) significantly and in a dose-dependent manner reduced convulsions or exhibited full protection in MES and PTZ convulsions model, respectively. Interestingly, the protective effects observed for the ( R )-enantiomer ( 3 ) in MES model were significantly greater than those of the standard H 3 R inverse agonist/antagonist pitolisant, comparable with

  19. Adenosine receptor antagonist and augmented vasodilation during hypoxic exercise

    PubMed Central

    Madery, Brandon D.; Pike, Tasha L.; Eisenach, John H.; Dietz, Niki M.; Joyner, Michael J.; Wilkins, Brad W.

    2009-01-01

    We tested the hypothesis that adenosine contributes to augmented skeletal muscle vasodilation during hypoxic exercise. In separate protocols, subjects performed incremental rhythmic forearm exercise (10% and 20% of maximum) during normoxia and normocapnic hypoxia (80% arterial O2 saturation). In protocol 1 (n = 8), subjects received an intra-arterial administration of saline (control) and aminophylline (adenosine receptor antagonist). In protocol 2 (n = 10), subjects received intra-arterial phentolamine (α-adrenoceptor antagonist) and combined phentolamine and aminophylline administration. Forearm vascular conductance (FVC; in ml·min−1·100 mmHg−1) was calculated from forearm blood flow (in ml/min) and blood pressure (in mmHg). In protocol 1, the change in FVC (ΔFVC; change from normoxic baseline) during hypoxic exercise with saline was 172 ± 29 and 314 ± 34 ml·min−1·100 mmHg−1 (10% and 20%, respectively). Aminophylline administration did not affect ΔFVC during hypoxic exercise at 10% (190 ± 29 ml·min−1·100 mmHg−1, P = 0.4) or 20% (287 ± 48 ml·min−1·100 mmHg−1, P = 0.3). In protocol 2, ΔFVC due to hypoxic exercise with phentolamine infusion was 313 ± 30 and 453 ± 41 ml·min−1·100 mmHg−1 (10% and 20% respectively). ΔFVC was similar at 10% (352 ± 39 ml·min−1·100 mmHg−1, P = 0.8) and 20% (528 ± 45 ml·min−1·100 mmHg−1, P = 0.2) hypoxic exercise with combined phentolamine and aminophylline. In contrast, ΔFVC to exogenous adenosine was reduced by aminophylline administration in both protocols (P < 0.05 for both). These observations suggest that adenosine receptor activation is not obligatory for the augmented hyperemia during hypoxic exercise in humans. PMID:19661449

  20. Treatment of pruritus with topically applied opiate receptor antagonist.

    PubMed

    Bigliardi, Paul L; Stammer, Holger; Jost, Gerhard; Rufli, Theo; Büchner, Stanislaw; Bigliardi-Qi, Mei

    2007-06-01

    Pruritus is the most common and distressing skin symptom, and treatment of itch is a problem for thousands of people. The currently available therapies are not very effective. Therefore there is an urgent need to find new effective topical drugs against itching. We conducted two separate studies to evaluate the efficacy of topically applied naltrexone, an opioid receptor antagonist, in the treatment of severe pruritus. The objective of the first open study was to correlate the clinical efficacy of topically applied naltrexone in different pruritic skin disorders to a change of epidermal mu-opiate receptor (MOR) expression. The second study was a double-blind, placebo-controlled, crossover study on pruritus in atopic dermatitis. Initially we performed an open pilot study on 18 patients with different chronic pruritic disorders using a topical formulation of 1% naltrexone for 2 weeks. A punch biopsy was performed in 11 patients before and after the application of the naltrexone cream and the staining of epidermal MOR was measured. Subsequently, a randomized, placebo-controlled, crossover trial was performed with the same formulation. We included in this trial 40 patients with localized and generalized atopic dermatitis with severe pruritus. In the open study more than 70% of the patients using the 1% naltrexone cream experienced a significant reduction of pruritus. More interestingly, the topical treatment with naltrexone caused an increase of epidermal MOR staining. The regulation of the epidermal opioid receptor correlated with the clinical assessment. The placebo-controlled, crossover trial demonstrated clearly that the cream containing naltrexone had an overall 29.4% better effect compared with placebo. The formulation containing naltrexone required a median of 46 minutes to reduce the itch symptoms to 50%; the placebo, 74 minutes. We could only take biopsy specimens in 11 patients, which means that a satisfactory statistical analysis of the changes of epidermal

  1. Nonpeptide vasopressin antagonists: a new group of hormone blockers entering the scene.

    PubMed

    Mayinger, B; Hensen, J

    1999-01-01

    After the story of success of hormone blockers for catecholamines, aldosterone and angiotensin II and their successful implementation into clinical practice another endocrine cardiovascular system has come into focus. It has long been known, that the hormone vasopressin plays an important role in peripheral vasoconstriction, hypertension and in several disease conditions with dilutional hyponatremia in edematous disorders, like congestive heart failure, liver cirrhosis, SIADH and nephrotic syndrome. A series of orally active nonpeptide antagonists against the vasopressin receptor subtypes has recently been synthesized and is now under intensive examination. Nonpeptide V1a-receptor specific antagonists, OPC 21268 and SR 49059, nonpeptide V2-receptor specific antagonists, SR 121463 A and VPA 985, and combined V1a-/V2-receptor antagonists, OPC 31260 and YM 087, have become available for clinical research. AVP-V2-receptor antagonists lead to a dose-dependent diabetes insipidus in animals and man. The term aquaretic drugs (aquaretics) has been coined for these drugs to highlight their different mechanism compared to the saluretic diuretic furosemide. V1a-receptor antagonists might offer new therapeutic advantages in the treatment of vasoconstriction and hypertension. Combined V1a-/V2-receptor antagonists might be beneficial in the treatment of congestive heart failure. Early results are promising and now need to be confirmed in large clinical studies.

  2. Isolation and characterization of antagonistic fungi against potato scab pathogens from potato field soils.

    PubMed

    Tagawa, Masahiro; Tamaki, Hideyuki; Manome, Akira; Koyama, Osamu; Kamagata, Yoichi

    2010-04-01

    Potato scab is a serious plant disease caused by several Streptomyces sp., and effective control methods remain unavailable. Although antagonistic bacteria and phages against potato scab pathogens have been reported, to the best of our knowledge, there is no information about fungi that are antagonistic to the pathogens. The aim of this study was to isolate fungal antagonists, characterize their phylogenetic positions, determine their antagonistic activities against potato scab pathogens, and highlight their potential use as control agents under lower pH conditions. Fifteen fungal stains isolated from potato field soils were found to have antagonistic activity against three well-known potato scab pathogens: Streptomyces scabiei, Streptomyces acidiscabiei, and Streptomyces turgidiscabiei. These 15 fungal strains were phylogenetically classified into at least six orders and nine genera based on 18S rRNA gene sequencing analysis. These fungal isolates were related to members of the genera Penicillium, Eupenicillium, Chaetomium, Fusarium, Cladosporium, Mortierella, Kionochaeta, Pseudogymnoascus, and Lecythophora. The antagonistic activities of most of the fungal isolates were highly strengthened under the lower pH conditions, suggesting the advantage of combining their use with a traditional method such as soil acidification. This is the first report to demonstrate that phylogenetically diverse fungi show antagonistic activity against major potato scab pathogens. These fungal strains could be used as potential agents to control potato scab disease.

  3. FGFR antagonist induces protective autophagy in FGFR1-amplified breast cancer cell

    SciTech Connect

    Chen, Yi; Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, Chengdu; Xie, Xiaoyan

    Breast cancer, representing approximately 30% of all gynecological cancer cases diagnosed yearly, is a leading cause of cancer-related mortality for women. Amplification of FGFR1 is frequently observed in breast cancers and is associated with poor prognosis. Though FGFRs have long been considered as anti-cancer drug targets, and a cluster of FGFR antagonists are currently under clinical trials, the precise cellular responses under the treatment of FGFR antagonists remains unclear. Here, we show that PD166866, an FGFR1-selective inhibitor, inhibits proliferation and triggers anoikis in FGFR1-amplified breast cancer cell lines. Notably, we demonstrate that PD166866 induces autophagy in FGFR1-amplified breast cancer cellmore » lines, while blockage of autophagy by Atg5 knockdown further enhances the anti-proliferative activities of PD166866. Moreover, mechanistic study reveals that PD166866 induces autophagy through repressing Akt/mTOR signaling pathway. Together, the present study provides new insights into the molecular mechanisms underlying the anti-tumor activities of FGFR antagonists, and may further assist the FGFRs-based drug discovery. -- Highlights: •FGFR1 antagonist inhibits cell viability in FGFR1-amplified breast cancer cells. •FGFR1 antagonist induces autophagy in FGFR1-amplified breast cancer cells. •FGFR1 antagonist-induced autophagy is protective. •FGFR1 antagonist induces autophagy by inhibiting Akt/mTOR pathway.« less

  4. Investigational opioid antagonists for treating opioid-induced bowel dysfunction.

    PubMed

    Mozaffari, Shilan; Nikfar, Shekoufeh; Abdollahi, Mohammad

    2018-03-01

    Opioids have been highlighted for their role in pain relief among cancer and non-cancer patients. Novel agents have been investigated to reduce opioid-induced constipation (OIC) as the main adverse effect that may lead to treatment discontinuation. Development of peripherally acting mu-opioid receptor antagonists (PAMORA) has resulted in a novel approach to preserve the efficacy of pain control along with less OIC. Areas covered: Clinical evidence for investigational PAMORAs was reviewed and clinical trials on investigational agents to reduce OIC were included. TD-1211 is currently being evaluated in Phase II clinical trial. Oxycodone-naltrexone and ADL-5945 went through Phase III clinical trials, but have been discontinued. Expert opinion: There is a substantial need to develop agents with specific pharmacokinetic properties to meet the needs of patients with underlying diseases. Holding the efficacy of a medicine with the highest selectivity on targeted receptors and the least adverse effects is the main approach in upcoming investigations to improve patients' quality of life (QoL). Novel agents to reduce opioid-induced bowel dysfunction (OIBD) that do not reverse peripherally mediated pain analgesia are of great interest. Direct comparison of available agents in this field is lacking in the literature.

  5. Calcium antagonists. A role in the management of cyanide poisoning

    SciTech Connect

    Maduh, E.U.; Porter, D.W.; Baskin, S.I.

    1993-12-31

    The physiological role of calcium was demonstrated by Ringer (1883) when he linked the omission of calcium (Ca++) from the bathing medium to the induction of cardiac arrest in the isolated frog heart. This observation established that Ca++ controlled muscle contraction but it was not until the autumn of 1963 that the specific pharmacological significance of this contribution was realised by Fleckenstein (1964), leading to the development of Ca++ antagonism as a concept in drug action (Fleckenstein 1977). Identifying the precise role of Ca++ ions in toxic cell injury and tissue death attributable to drug and chemical intoxication has laggedmore » behind developments in Ca++ physiology and pharmacology and to date, much remains to be learned, although studies aimed at characterising the role of Ca++ in cytotoxic cell injury are receiving intense attention (Bondy Komulainen 1988; Maduh et al. l988a, l99Oa,b; Orrenius et al. 1989; Trump et al. 1989). On the other hand, the importance of cyanide as a poison has been known from antiquity (for references to earlier literature see Baskin Fricke 1992; Solomonson 1981). In experimental cyanide poisoning, recent studies have examined alterations in cell Ca++ and the influence of Ca++ antagonists in the management of this chemical toxicological emergency. These efforts have principally focused on the cellular Ca++ homeostasis system, its interrelationship with cellular components, and its susceptibility to cyanide action.« less

  6. Locomotor adaptation to a soleus EMG-controlled antagonistic exoskeleton

    PubMed Central

    Kinnaird, Catherine R.; Ferris, Daniel P.

    2013-01-01

    Locomotor adaptation in humans is not well understood. To provide insight into the neural reorganization that occurs following a significant disruption to one's learned neuromuscular map relating a given motor command to its resulting muscular action, we tied the mechanical action of a robotic exoskeleton to the electromyography (EMG) profile of the soleus muscle during walking. The powered exoskeleton produced an ankle dorsiflexion torque proportional to soleus muscle recruitment thus limiting the soleus' plantar flexion torque capability. We hypothesized that neurologically intact subjects would alter muscle activation patterns in response to the antagonistic exoskeleton by decreasing soleus recruitment. Subjects practiced walking with the exoskeleton for two 30-min sessions. The initial response to the perturbation was to “fight” the resistive exoskeleton by increasing soleus activation. By the end of training, subjects had significantly reduced soleus recruitment resulting in a gait pattern with almost no ankle push-off. In addition, there was a trend for subjects to reduce gastrocnemius recruitment in proportion to the soleus even though only the soleus EMG was used to control the exoskeleton. The results from this study demonstrate the ability of the nervous system to recalibrate locomotor output in response to substantial changes in the mechanical output of the soleus muscle and associated sensory feedback. This study provides further evidence that the human locomotor system of intact individuals is highly flexible and able to adapt to achieve effective locomotion in response to a broad range of neuromuscular perturbations. PMID:23307949

  7. Side Effects of Leukotriene Receptor Antagonists in Asthmatic Children.

    PubMed

    Erdem, Semiha Bahceci; Nacaroglu, Hikmet Tekin; Unsal Karkiner, Canan Sule; Gunay, Ilker; Can, Demet

    2015-10-01

    Leukotriene receptor antagonists (LTRAs) are drugs which have been widely used more than ten years. As the use of LTRAs increases, our knowledge with respect to their side effects increases as well. The objective of our study was to evaluat the observed side effects of LTRAs used in patients with astma. 1024 patients treated only with LTRAs owing to asthma or early wheezing were included in the study for a five-year period. The observed side effects of LTRAs in these patients were retrospectively investigated. The side effects were divided into two parts as psychiatric and non-psychiatric. Among the 1024 cases included in the study, 67.5% of the patients out of 41 with side effects were male, 32.5% were female and the average age was 6.5 years. The rate of patients with asthma was 63.41% and 36.58% of the patients had early wheezing. It was determined that sex, age and diagnosis (early wheezing or asthma) of the patients were ineffective in the emergence of side effects. The average period for the emergence of side effects was the first month. It was observed that hyperactivity was the most frequently observed psychiatric side effect and that abdominal pain was the non-psychiatric side effect. The side effects of LTRAs were common in children. Therefore, patients must be informed at the beginning of the treatment and they must be evaluated at certain intervals.

  8. Signatures of Sex-Antagonistic Selection on Recombining Sex Chromosomes

    PubMed Central

    Kirkpatrick, Mark; Guerrero, Rafael F.

    2014-01-01

    Sex-antagonistic (SA) selection has major evolutionary consequences: it can drive genomic change, constrain adaptation, and maintain genetic variation for fitness. The recombining (or pseudoautosomal) regions of sex chromosomes are a promising setting in which to study SA selection because they tend to accumulate SA polymorphisms and because recombination allows us to deploy the tools of molecular evolution to locate targets of SA selection and quantify evolutionary forces. Here we use coalescent models to characterize the patterns of polymorphism expected within and divergence between recombining X and Y (or Z and W) sex chromosomes. SA selection generates peaks of divergence between X and Y that can extend substantial distances away from the targets of selection. Linkage disequilibrium between neutral sites is also inflated. We show how the pattern of divergence is altered when the SA polymorphism or the sex-determining region was recently established. We use data from the flowering plant Silene latifolia to illustrate how the strength of SA selection might be quantified using molecular data from recombining sex chromosomes. PMID:24578352

  9. Signatures of sex-antagonistic selection on recombining sex chromosomes.

    PubMed

    Kirkpatrick, Mark; Guerrero, Rafael F

    2014-06-01

    Sex-antagonistic (SA) selection has major evolutionary consequences: it can drive genomic change, constrain adaptation, and maintain genetic variation for fitness. The recombining (or pseudoautosomal) regions of sex chromosomes are a promising setting in which to study SA selection because they tend to accumulate SA polymorphisms and because recombination allows us to deploy the tools of molecular evolution to locate targets of SA selection and quantify evolutionary forces. Here we use coalescent models to characterize the patterns of polymorphism expected within and divergence between recombining X and Y (or Z and W) sex chromosomes. SA selection generates peaks of divergence between X and Y that can extend substantial distances away from the targets of selection. Linkage disequilibrium between neutral sites is also inflated. We show how the pattern of divergence is altered when the SA polymorphism or the sex-determining region was recently established. We use data from the flowering plant Silene latifolia to illustrate how the strength of SA selection might be quantified using molecular data from recombining sex chromosomes. Copyright © 2014 by the Genetics Society of America.

  10. Return of D4 Dopamine Receptor Antagonists in Drug Discovery.

    PubMed

    Lindsley, Craig W; Hopkins, Corey R

    2017-09-14

    The dopamine D 4 receptor garnered a great deal of interest in the early 1990s when studies showed the atypical antipsychotic clozapine possessed higher affinity for D 4 , relative to other dopamine receptor subtypes, and that this activity might underlie the unique clinical efficacy of clozapine. Unfortunately, D 4 antagonists that were developed for schizophrenia failed in the clinic. Thus, D 4 fell out of favor as a therapeutic target, and work in this area was silent for decades. Recently, D 4 ligands with improved selectivity for D 4 against not only D 1-3,5 but also other biogenic amine targets have emerged, and D 4 is once again in the spotlight as a novel target for both addiction and Parkinson's disease (PD), as well as other emerging diseases. This report will review the historical data for D 4 , review the known D 4 ligands, and then highlight new data supporting a role for D 4 inhibition in addiction, PD, and cancer.

  11. Locomotor adaptation to a soleus EMG-controlled antagonistic exoskeleton.

    PubMed

    Gordon, Keith E; Kinnaird, Catherine R; Ferris, Daniel P

    2013-04-01

    Locomotor adaptation in humans is not well understood. To provide insight into the neural reorganization that occurs following a significant disruption to one's learned neuromuscular map relating a given motor command to its resulting muscular action, we tied the mechanical action of a robotic exoskeleton to the electromyography (EMG) profile of the soleus muscle during walking. The powered exoskeleton produced an ankle dorsiflexion torque proportional to soleus muscle recruitment thus limiting the soleus' plantar flexion torque capability. We hypothesized that neurologically intact subjects would alter muscle activation patterns in response to the antagonistic exoskeleton by decreasing soleus recruitment. Subjects practiced walking with the exoskeleton for two 30-min sessions. The initial response to the perturbation was to "fight" the resistive exoskeleton by increasing soleus activation. By the end of training, subjects had significantly reduced soleus recruitment resulting in a gait pattern with almost no ankle push-off. In addition, there was a trend for subjects to reduce gastrocnemius recruitment in proportion to the soleus even though only the soleus EMG was used to control the exoskeleton. The results from this study demonstrate the ability of the nervous system to recalibrate locomotor output in response to substantial changes in the mechanical output of the soleus muscle and associated sensory feedback. This study provides further evidence that the human locomotor system of intact individuals is highly flexible and able to adapt to achieve effective locomotion in response to a broad range of neuromuscular perturbations.

  12. NMDA receptor antagonist ketamine impairs feature integration in visual perception.

    PubMed

    Meuwese, Julia D I; van Loon, Anouk M; Scholte, H Steven; Lirk, Philipp B; Vulink, Nienke C C; Hollmann, Markus W; Lamme, Victor A F

    2013-01-01

    Recurrent interactions between neurons in the visual cortex are crucial for the integration of image elements into coherent objects, such as in figure-ground segregation of textured images. Blocking N-methyl-D-aspartate (NMDA) receptors in monkeys can abolish neural signals related to figure-ground segregation and feature integration. However, it is unknown whether this also affects perceptual integration itself. Therefore, we tested whether ketamine, a non-competitive NMDA receptor antagonist, reduces feature integration in humans. We administered a subanesthetic dose of ketamine to healthy subjects who performed a texture discrimination task in a placebo-controlled double blind within-subject design. We found that ketamine significantly impaired performance on the texture discrimination task compared to the placebo condition, while performance on a control fixation task was much less impaired. This effect is not merely due to task difficulty or a difference in sedation levels. We are the first to show a behavioral effect on feature integration by manipulating the NMDA receptor in humans.

  13. Antagonistic Activity of Lactobacillus Isolates against Salmonella typhi In Vitro

    PubMed Central

    Abdel-Daim, Amira; Hassouna, Nadia; Hafez, Mohamed; Ashor, Mohamed Seif Aldeen; Aboulwafa, Mohammad M.

    2013-01-01

    Background. Enteric fever is a global health problem, and rapidly developing resistance to various drugs makes the situation more alarming. The potential use of Lactobacillus to control typhoid fever represents a promising approach, as it may exert protective actions through various mechanisms. Methods. In this study, the probiotic potential and antagonistic activities of 32 Lactobacillus isolates against Salmonella typhi were evaluated. The antimicrobial activity of cell free supernatants of Lactobacillus isolates, interference of Lactobacillus isolates with the Salmonella adherence and invasion, cytoprotective effect of Lactobacillus isolates, and possibility of concurrent use of tested Lactobacillus isolates and antibiotics were evaluated by testing their susceptibilities to antimicrobial agents, and their oxygen tolerance was also examined. Results. The results revealed that twelve Lactobacillus isolates could protect against Salmonella typhi infection through interference with both its growth and its virulence properties, such as adherence, invasion, and cytotoxicity. These Lactobacillus isolates exhibited MIC values for ciprofloxacin higher than those of Salmonella typhi and oxygen tolerance and were identified as Lactobacillus plantarum. Conclusion. The tested Lactobacillus plantarum isolates can be introduced as potential novel candidates that have to be subjected for in vivo and application studies for treatment and control of typhoid fever. PMID:24191248

  14. Novel Abscisic Acid Antagonists Identified with Chemical Array Screening.

    PubMed

    Ito, Takuya; Kondoh, Yasumitsu; Yoshida, Kazuko; Umezawa, Taishi; Shimizu, Takeshi; Shinozaki, Kazuo; Osada, Hiroyuki

    2015-11-01

    Abscisic acid (ABA) signaling is involved in multiple processes in plants, such as water stress control and seed dormancy. Major regulators of ABA signaling are the PYR/PYL/RCAR family receptor proteins, group A protein phosphatases 2C (PP2Cs), and subclass III of SNF1-related protein kinase 2 (SnRK2). Novel ABA agonists and antagonists to modulate the functions of these proteins would not only contribute to clarification of the signaling mechanisms but might also be used to improve crop yields. To obtain small molecules that interact with Arabidopsis ABA receptor PYR1, we screened 24 275 compounds from a chemical library at the RIKEN Natural Products Depository by using a chemical array platform. Subsequent SnRK2 and PP2C assays narrowed down the candidates to two molecules. One antagonized ABA in a competitive manner and inhibited the formation of the PYR1-ABA-PP2C ternary complex. These compounds might have potential as bioprobes to analyze ABA signaling. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. The effect of epistasis on sexually antagonistic genetic variation

    PubMed Central

    Arnqvist, Göran; Vellnow, Nikolas; Rowe, Locke

    2014-01-01

    There is increasing evidence of segregating sexually antagonistic (SA) genetic variation for fitness in laboratory and wild populations, yet the conditions for the maintenance of such variation can be restrictive. Epistatic interactions between genes can contribute to the maintenance of genetic variance in fitness and we suggest that epistasis between SA genes should be pervasive. Here, we explore its effect on SA genetic variation in fitness using a two locus model with negative epistasis. Our results demonstrate that epistasis often increases the parameter space showing polymorphism for SA loci. This is because selection in one locus is affected by allele frequencies at the other, which can act to balance net selection in males and females. Increased linkage between SA loci had more marginal effects. We also show that under some conditions, large portions of the parameter space evolve to a state where male benefit alleles are fixed at one locus and female benefit alleles at the other. This novel effect of epistasis on SA loci, which we term the ‘equity effect’, may have important effects on population differentiation and may contribute to speciation. More generally, these results support the suggestion that epistasis contributes to population divergence. PMID:24870040

  16. Rap1 and Rap2 Antagonistically Control Endothelial Barrier Resistance

    PubMed Central

    Pannekoek, Willem-Jan; Linnemann, Jelena R.; Brouwer, Patricia M.; Bos, Johannes L.; Rehmann, Holger

    2013-01-01

    Rap1 and Rap2 are closely related proteins of the Ras family of small G-proteins. Rap1 is well known to regulate cell-cell adhesion. Here, we have analysed the effect of Rap-mediated signalling on endothelial permeability using electrical impedance measurements of HUVEC monolayers and subsequent determination of the barrier resistance, which is a measure for the ease with which ions can pass cell junctions. In line with its well-established effect on cell-cell junctions, depletion of Rap1 decreases, whereas activation of Rap1 increases barrier resistance. Despite its high sequence homology with Rap1, depletion of Rap2 has an opposite, enhancing, effect on barrier resistance. This effect can be mimicked by depletion of the Rap2 specific activator RasGEF1C and the Rap2 effector MAP4K4, establishing Rap2 signalling as an independent pathway controlling barrier resistance. As simultaneous depletion or activation of both Rap1 and Rap2 results in a barrier resistance comparable to control cells, Rap1 and Rap2 control barrier resistance in a reciprocal manner. This Rap1-antagonizing effect of Rap2 is established independent of junctional actin formation. These data establish that endothelial barrier resistance is determined by the combined antagonistic actions of Rap1 and Rap2. PMID:23469100

  17. Macromolecular beta-adrenergic antagonists discriminating between receptor and antibody.

    PubMed Central

    Pitha, J; Zjawiony, J; Lefkowitz, R J; Caron, M G

    1980-01-01

    The beta-adrenergic antagonist, alprenolol, was attached in an irreversible manner to macromolecular dextran via side arms that differed in length. The ability of these macromolecules to bind to the beta-adrenergic receptor of frog erythrocytes and to catecholamine-binding antibodies raised against partially purified receptors was studied. Compared to the parent drug the potency of binding of macromolecular alprenolol to the receptor decreased about 1/10, 1/600, and 1/8000 when the length of the arm separating alprenolol from the dextran moiety was 13, 8, and 4 atoms, respectively. In contrast, the binding potencies of the parent drug and of all its macromolecular derivatives for the antibody were within the same order of magnitude. Thus, conversion of a drug to a macromolecular form may not only sustain its binding activity but may also lead in a higher selectivity. The macromolecular derivatives described here may be suitable probes for investigation of the location and of the molecular properties of the binding sites for beta-adrenergic drugs. PMID:6154947

  18. Management of hyperkalaemia consequent to mineralocorticoid-receptor antagonist therapy.

    PubMed

    Roscioni, Sara S; de Zeeuw, Dick; Bakker, Stephan J L; Lambers Heerspink, Hiddo J

    2012-12-01

    Mineralocorticoid-receptor antagonists (MRAs) reduce blood pressure and albuminuria in patients treated with angiotensin-converting-enzyme inhibitors or angiotensin-II-receptor blockers. The use of MRAs, however, is limited by the occurrence of hyperkalaemia, which frequently occurs in patients older than 65 years with impaired kidney function, and/or diabetes. Patients with these characteristics might still benefit from MRA therapy, however, and should not be excluded from this treatment option. This limitation raises the question of how to optimize the therapeutic use of MRAs in this population of patients. Understanding the individual variability in patients' responses to MRAs, in terms of albuminuria, blood pressure and serum potassium levels, might lead to targeted intervention. MRA use might be restricted to patients with high levels of mineralocorticoid activity, evaluated by circulating renin and aldosterone levels or renal excretion of potassium. In addition, reviewing the patient's diet and concomitant medications might prove useful in reducing the risk of developing subsequent hyperkalaemia. If hyperkalaemia does develop, treatment options exist to decrease potassium levels, including administration of calcium gluconate, insulin, β(2)-agonists, diuretics and cation-exchange resins. In combination with novel aldosterone blockers, these strategies might offer a rationale with which to optimize therapeutic intervention and extend the population of patients who can benefit from use of MRAs.

  19. [Mineralocorticoid receptor antagonists in chronic kidney disease - pros and cons].

    PubMed

    Jędras, Mirosław; Filipowicz, Ewa

    2017-01-01

    Aldosterone takes part in the regulation of body fluid volume, blood pressure and kalemia. In a number of pathological conditions, including chronic kidney disease (CKD), secondary hyperaldosteronism occurs, leading to development of edema, hypervolemia and hypertension. Aldosterone has also a proinflammatory action, leading to heart and blood vessels damage, and is an independent risk factor of death. Some of the research conducted to confirm the expected benefits of angiotensin converting enzyme inhibitors (ACEi) and angiotensin II receptor blockers (ARB) therapy in CKD patients did not yield positive results, probably due to "aldosterone escape". Mineralocorticoid receptor antagonists (MRA) are being introduced also in the treatment of CKD patients, although the risk of developing hyperkalemia exists. A number of papers suggest a positive influence of MRA on slowing down the progression of renal failure, reduction of cardiovascular risk, and decreasing mortality, with relative safety of treatment, however the data are based on small and heterogenous groups of patients, therefore conclusive information is expected from large trials which are currently being conducted (BARACK D, ALCHEMIST).

  20. ST 1535: a preferential A2A adenosine receptor antagonist.

    PubMed

    Stasi, Maria Antonietta; Borsini, Franco; Varani, Katia; Vincenzi, Fabrizio; Di Cesare, Maria Assunta; Minetti, Patrizia; Ghirardi, Orlando; Carminati, Paolo

    2006-10-01

    Antagonism of the A2A adenosine function has proved beneficial in the treatment of Parkinson's disease, in that it increases L-dopa therapeutical effects without concomitant worsening of its side-effects. In this paper we describe a preferential A2A adenosine antagonist, ST 1535, with long-lasting pharmacodynamic effects. It competitively antagonizes the effects of the A2A adenosine agonist NECA on cAMP in cells cloned with the human A2A adenosine receptor (IC50=353+/-30 nM), and the effects of the A1 adenosine agonist CHA on cAMP in cells cloned with the human A1 adenosine receptor (IC50=510+/-38 nM). ST 1535, at oral doses of 5 and 10 mg/kg, antagonizes catalepsy induced by intracerebroventricular administration of the A2A adenosine agonist CGS 21680 (10 microg/5 microl) in mice. At oral doses ranging between 5 and 20 mg/kg, ST 1535 induces hypermotility and antagonizes haloperidol-induced catalepsy in mice up to 7 h. Oral ST 1535, at 1.25 and 2.5 mg/kg, potentiates L-dopa effects in reducing haloperidol-induced catalepsy. ST 1535 represents a potential new compound, with long-lasting activity, for the treatment of Parkinson's disease.

  1. Antagonistic autoregulation speeds up a homogeneous response in Escherichia coli.

    PubMed

    Rodrigo, Guillermo; Bajic, Djordje; Elola, Ignacio; Poyatos, Juan F

    2016-10-31

    By integrating positive and negative feedback loops, biological systems establish intricate gene expression patterns linked to multistability, pulsing, and oscillations. This depends on the specific characteristics of each interlinked feedback, and thus one would expect additional expression programs to be found. Here, we investigate one such program associated with an antagonistic positive and negative transcriptional autoregulatory motif derived from the multiple antibiotic resistance (mar) system of Escherichia coli. We studied the dynamics of the system by combining a predictive mathematical model with high-resolution experimental measures of the response both at the population and single-cell level. We show that in this motif the weak positive autoregulation does not slow down but rather enhances response speedup in combination with a strong negative feedback loop. This balance of feedback strengths anticipates a homogeneous population phenotype, which we corroborate experimentally. Theoretical analysis also emphasized the specific molecular properties that determine the dynamics of the mar phenotype. More broadly, response acceleration could provide a rationale for the presence of weak positive feedbacks in other biological scenarios exhibiting these interlinked regulatory architectures.

  2. Endosperm and Nucellus Develop Antagonistically in Arabidopsis Seeds

    PubMed Central

    Xu, Wenjia; Coen, Olivier; Pechoux, Christine; Magnani, Enrico

    2016-01-01

    In angiosperms, seed architecture is shaped by the coordinated development of three genetically different components: embryo, endosperm, and maternal tissues. The relative contribution of these tissues to seed mass and nutrient storage varies considerably among species. The development of embryo, endosperm, or nucellus maternal tissue as primary storage compartments defines three main typologies of seed architecture. It is still debated whether the ancestral angiosperm seed accumulated nutrients in the endosperm or the nucellus. During evolution, plants shifted repeatedly between these two storage strategies through molecular mechanisms that are largely unknown. Here, we characterize the regulatory pathway underlying nucellus and endosperm tissue partitioning in Arabidopsis thaliana. We show that Polycomb-group proteins repress nucellus degeneration before fertilization. A signal initiated in the endosperm by the AGAMOUS-LIKE62 MADS box transcription factor relieves this Polycomb-mediated repression and therefore allows nucellus degeneration. Further downstream in the pathway, the TRANSPARENT TESTA16 (TT16) and GORDITA MADS box transcription factors promote nucellus degeneration. Moreover, we demonstrate that TT16 mediates the crosstalk between nucellus and seed coat maternal tissues. Finally, we characterize the nucellus cell death program and its feedback role in timing endosperm development. Altogether, our data reveal the antagonistic development of nucellus and endosperm, in coordination with seed coat differentiation. PMID:27233529

  3. Effects of Cannabinoid Agonists and Antagonists on Sleep and Breathing in Sprague-Dawley Rats.

    PubMed

    Calik, Michael W; Carley, David W

    2017-09-01

    There are no pharmacological treatments for obstructive sleep apnea syndrome, but dronabinol showed promise in a small pilot study. In anesthetized rats, dronabinol attenuates reflex apnea via activation of cannabinoid (CB) receptors located on vagal afferents; an effect blocked by cannabinoid type 1 (CB1) and/or type 2 (CB2) receptor antagonists. Here, using a natural model of central sleep apnea, we examine the effects of dronabinol, alone and in combination with selective antagonists in conscious rats chronically instrumented to stage sleep and measure cessation of breathing. Adult male Sprague-Dawley rats were anesthetized and implanted with bilateral stainless steel screws into the skull for electroencephalogram recording and bilateral wire electrodes into the nuchal muscles for electromyogram recording. Each animal was recorded by polysomnography on multiple occasions separated by at least 3 days. The study was a fully nested, repeated measures crossover design, such that each rat was recorded following each of 8 intraperitoneal injections: vehicle; vehicle and CB1 antagonist (AM 251); vehicle and CB2 antagonist (AM 630); vehicle and CB1/CB2 antagonist; dronabinol; dronabinol and CB1 antagonist; dronabinol and CB2 antagonist; and dronabinol and CB1/CB2 antagonist. Dronabinol decreased the percent time spent in rapid eye movement (REM) sleep. CB receptor antagonists did not reverse this effect. Dronabinol also decreased apneas during sleep, and this apnea suppression was reversed by CB1 or CB1/CB2 receptor antagonism. Dronabinol's effects on apneas were dependent on CB1 receptor activation, while dronabinol's effects on REM sleep were CB receptor-independent. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

  4. A General Population Genetic Framework for Antagonistic Selection That Accounts for Demography and Recurrent Mutation

    PubMed Central

    Connallon, Tim; Clark, Andrew G.

    2012-01-01

    Antagonistic selection—where alleles at a locus have opposing effects on male and female fitness (“sexual antagonism”) or between components of fitness (“antagonistic pleiotropy”)—might play an important role in maintaining population genetic variation and in driving phylogenetic and genomic patterns of sexual dimorphism and life-history evolution. While prior theory has thoroughly characterized the conditions necessary for antagonistic balancing selection to operate, we currently know little about the evolutionary interactions between antagonistic selection, recurrent mutation, and genetic drift, which should collectively shape empirical patterns of genetic variation. To fill this void, we developed and analyzed a series of population genetic models that simultaneously incorporate these processes. Our models identify two general properties of antagonistically selected loci. First, antagonistic selection inflates heterozygosity and fitness variance across a broad parameter range—a result that applies to alleles maintained by balancing selection and by recurrent mutation. Second, effective population size and genetic drift profoundly affect the statistical frequency distributions of antagonistically selected alleles. The “efficacy” of antagonistic selection (i.e., its tendency to dominate over genetic drift) is extremely weak relative to classical models, such as directional selection and overdominance. Alleles meeting traditional criteria for strong selection (Nes >> 1, where Ne is the effective population size, and s is a selection coefficient for a given sex or fitness component) may nevertheless evolve as if neutral. The effects of mutation and demography may generate population differences in overall levels of antagonistic fitness variation, as well as molecular population genetic signatures of balancing selection. PMID:22298707

  5. A general population genetic framework for antagonistic selection that accounts for demography and recurrent mutation.

    PubMed

    Connallon, Tim; Clark, Andrew G

    2012-04-01

    Antagonistic selection--where alleles at a locus have opposing effects on male and female fitness ("sexual antagonism") or between components of fitness ("antagonistic pleiotropy")--might play an important role in maintaining population genetic variation and in driving phylogenetic and genomic patterns of sexual dimorphism and life-history evolution. While prior theory has thoroughly characterized the conditions necessary for antagonistic balancing selection to operate, we currently know little about the evolutionary interactions between antagonistic selection, recurrent mutation, and genetic drift, which should collectively shape empirical patterns of genetic variation. To fill this void, we developed and analyzed a series of population genetic models that simultaneously incorporate these processes. Our models identify two general properties of antagonistically selected loci. First, antagonistic selection inflates heterozygosity and fitness variance across a broad parameter range--a result that applies to alleles maintained by balancing selection and by recurrent mutation. Second, effective population size and genetic drift profoundly affect the statistical frequency distributions of antagonistically selected alleles. The "efficacy" of antagonistic selection (i.e., its tendency to dominate over genetic drift) is extremely weak relative to classical models, such as directional selection and overdominance. Alleles meeting traditional criteria for strong selection (N(e)s > 1, where N(e) is the effective population size, and s is a selection coefficient for a given sex or fitness component) may nevertheless evolve as if neutral. The effects of mutation and demography may generate population differences in overall levels of antagonistic fitness variation, as well as molecular population genetic signatures of balancing selection.

  6. Chloroquine, quinine, procaine, quinidine, tricyclic antidepressants, and methylxanthines as prostaglandin agonists and antagonists.

    PubMed

    Manku, M S; Horrobin, D F

    1976-11-20

    Chloroquine, quanine, procaine, quinidine, clomipramine, theophylline, and caffeine have been shown to be strong prostaglandin antagonists and weak agonists. The antagonist effect is clearly demonstrable at concentrations reached in human plasma when the drugs are used therapeutically. This suggests that prostaglandins are important in several situations in which their role has hitherto been unsuspected. New approaches to the development of prostaglandin antagonists and new uses for established drugs are indicated. In a preliminary study chloroquine has been successfully used to close patent ductus arteriosus in three infants.

  7. AZD-4818, a chemokine CCR1 antagonist: WO2008103126 and WO2009011653.

    PubMed

    Norman, Peter

    2009-11-01

    The applications WO2008103126 and WO2009011653, respectively, claim: i) Combinations of a spirocyclic piperidine chemokine CCR1 antagonist with a corticosteroid, and their use for the treatment of asthma and chronic obstructive pulmonary disease. ii) Processes for the preparation of a spirocyclic piperidine derivative, a chemokine CCR1 antagonist. These applications point to the preferred compound being a development compound. The evidence for this compound being AZD-4818, a chemokine CCR1 antagonist that was in Phase II development for the treatment of chronic obstructive pulmonary disease, is reviewed in the light of these and earlier patents relating to it.

  8. Oral tremor induced by the muscarinic agonist pilocarpine is suppressed by the adenosine A2A antagonists MSX-3 and SCH58261, but not the adenosine A1 antagonist DPCPX.

    PubMed

    Collins, Lyndsey E; Galtieri, Daniel J; Brennum, Lise T; Sager, Thomas N; Hockemeyer, Jörg; Müller, Christa E; Hinman, James R; Chrobak, James J; Salamone, John D

    2010-02-01

    Tremulous jaw movements in rats, which can be induced by dopamine (DA) antagonists, DA depletion, and cholinomimetics, have served as a useful model for studies of tremor. Although adenosine A(2A) antagonists can reduce the tremulous jaw movements induced by DA antagonists and DA depletion, there are conflicting reports about the interaction between adenosine antagonists and cholinomimetic drugs. The present studies investigated the ability of adenosine antagonists to reverse the tremorogenic effect of the muscarinic agonist pilocarpine. While the adenosine A(2A) antagonist MSX-3 was incapable of reversing the tremulous jaw movements induced by the 4.0mg/kg dose of pilocarpine, both MSX-3 and the adenosine A(2A) antagonist SCH58261 reversed the tremulous jaw movements elicited by 0.5mg/kg pilocarpine. Systemic administration of the adenosine A(1) antagonist DPCPX failed to reverse the tremulous jaw movements induced by either an acute 0.5mg/kg dose of the cholinomimetic pilocarpine or the DA D2 antagonist pimozide, indicating that the tremorolytic effects of adenosine antagonists may be receptor subtype specific. Behaviorally active doses of MSX-3 and SCH 58261 showed substantial in vivo occupancy of A(2A) receptors, but DPCPX did not. The results of these studies support the use of adenosine A(2A) antagonists for the treatment of tremor. Copyright 2009 Elsevier Inc. All rights reserved.

  9. Statin use decreases coagulation in users of vitamin K antagonists.

    PubMed

    van Rein, Nienke; Biedermann, J S; Bonafacio, S M; Kruip, M J H A; van der Meer, F J M; Lijfering, W M

    2016-12-01

    The purpose of the study is to determine the immediate and long-term effect of statins on coagulation in patients treated with vitamin K antagonists (VKAs). We selected patients on VKAs of two Dutch anticoagulation clinics who initiated treatment with a statin between 2009 and 2013. Patients who initiated or stopped concomitant drugs that interact with VKAs or were hospitalised during follow-up were excluded. The VKA dosage (mg/day) after statin initiation was compared with the last VKA dosage before the statin was started. Immediate and long-term differences in VKA dosage (at 6 and 12 weeks) were calculated with a paired student t test. Four hundred thirty-five phenprocoumon users (mean age 70 years, 60 % men) and 303 acenocoumarol users (mean age 69 years, 58 % men) were included. After start of statin use, the immediate phenprocoumon dosage was 0.02 mg/day (95 % CI, 0.00 to 0.03) lower. At 6 and 12 weeks, these phenprocoumon dosages were 0.03 (95 % CI, 0.01 to 0.05) and 0.07 mg/day (95 % CI, 0.04 to 0.09) lower as compared with the dosage before first statin use. In acenocoumarol users, VKA dosage was 0.04 mg/day (95%CI, 0.01 to 0.07) (immediate effect), 0.10 (95 % CI, 0.03 to 0.16) (at 6 weeks), and 0.11 mg/day (95 % CI, 0.04 to 0.18) (after 12 weeks) lower. Initiation of statin treatment was associated with an immediate and long-term minor although statistically significant decrease in VKA dosage in both phenprocoumon and acenocoumarol users, which suggests that statins may have anticoagulant properties.

  10. Thrombin-receptor antagonist vorapaxar in acute coronary syndromes.

    PubMed

    Tricoci, Pierluigi; Huang, Zhen; Held, Claes; Moliterno, David J; Armstrong, Paul W; Van de Werf, Frans; White, Harvey D; Aylward, Philip E; Wallentin, Lars; Chen, Edmond; Lokhnygina, Yuliya; Pei, Jinglan; Leonardi, Sergio; Rorick, Tyrus L; Kilian, Ann M; Jennings, Lisa H K; Ambrosio, Giuseppe; Bode, Christoph; Cequier, Angel; Cornel, Jan H; Diaz, Rafael; Erkan, Aycan; Huber, Kurt; Hudson, Michael P; Jiang, Lixin; Jukema, J Wouter; Lewis, Basil S; Lincoff, A Michael; Montalescot, Gilles; Nicolau, José Carlos; Ogawa, Hisao; Pfisterer, Matthias; Prieto, Juan Carlos; Ruzyllo, Witold; Sinnaeve, Peter R; Storey, Robert F; Valgimigli, Marco; Whellan, David J; Widimsky, Petr; Strony, John; Harrington, Robert A; Mahaffey, Kenneth W

    2012-01-05

    Vorapaxar is a new oral protease-activated-receptor 1 (PAR-1) antagonist that inhibits thrombin-induced platelet activation. In this multinational, double-blind, randomized trial, we compared vorapaxar with placebo in 12,944 patients who had acute coronary syndromes without ST-segment elevation. The primary end point was a composite of death from cardiovascular causes, myocardial infarction, stroke, recurrent ischemia with rehospitalization, or urgent coronary revascularization. Follow-up in the trial was terminated early after a safety review. After a median follow-up of 502 days (interquartile range, 349 to 667), the primary end point occurred in 1031 of 6473 patients receiving vorapaxar versus 1102 of 6471 patients receiving placebo (Kaplan-Meier 2-year rate, 18.5% vs. 19.9%; hazard ratio, 0.92; 95% confidence interval [CI], 0.85 to 1.01; P=0.07). A composite of death from cardiovascular causes, myocardial infarction, or stroke occurred in 822 patients in the vorapaxar group versus 910 in the placebo group (14.7% and 16.4%, respectively; hazard ratio, 0.89; 95% CI, 0.81 to 0.98; P=0.02). Rates of moderate and severe bleeding were 7.2% in the vorapaxar group and 5.2% in the placebo group (hazard ratio, 1.35; 95% CI, 1.16 to 1.58; P<0.001). Intracranial hemorrhage rates were 1.1% and 0.2%, respectively (hazard ratio, 3.39; 95% CI, 1.78 to 6.45; P<0.001). Rates of nonhemorrhagic adverse events were similar in the two groups. In patients with acute coronary syndromes, the addition of vorapaxar to standard therapy did not significantly reduce the primary composite end point but significantly increased the risk of major bleeding, including intracranial hemorrhage. (Funded by Merck; TRACER ClinicalTrials.gov number, NCT00527943.).

  11. Cannabinoid type 1 receptor antagonists for smoking cessation.

    PubMed

    Cahill, Kate; Ussher, Michael H

    2011-03-16

    Selective type 1 cannabinoid (CB1) receptor antagonists may assist with smoking cessation by restoring the balance of the endocannabinoid system, which can be disrupted by prolonged use of nicotine. They also seeks to address many smokers' reluctance to persist with a quit attempt because of concerns about weight gain. To determine whether selective CB1 receptor antagonists (currently rimonabant and taranabant) increase the numbers of people stopping smoking To assess their effects on weight change in successful quitters and in those who try to quit but fail. We searched the Cochrane Tobacco Addiction Review Group specialized register for trials, using the terms ('rimonabant' or 'taranabant') and 'smoking' in the title or abstract, or as keywords. We also searched MEDLINE, EMBASE, CINAHL and PsycINFO, using major MESH terms. We acquired electronic or paper copies of posters of preliminary trial results presented at the American Thoracic Society Meeting in 2005, and at the Society for Research on Nicotine and Tobacco European Meeting 2006. We also attempted to contact the authors of ongoing studies of rimonabant, and Sanofi Aventis (manufacturers of rimonabant). The most recent search was in January 2011. Types of studies Randomized controlled trialsTypes of participants Adult smokersTypes of interventions Selective CB1 receptor antagonists, such as rimonabant and taranabant. Types of outcome measures The primary outcome is smoking status at a minimum of six months after the start of treatment. We preferred sustained cessation rates to point prevalence, and biochemically verified cessation to self-reported quitting. We regarded smokers who drop out or are lost to follow up as continuing smokers. We have noted any adverse effects of treatment.A secondary outcome is weight change associated with the cessation attempt. Two authors checked the abstracts for relevance, and attempted to acquire full trial reports. One author extracted the data, and a second author checked

  12. Antiviral activity of formyl peptide receptor 2 antagonists against influenza viruses.

    PubMed

    Courtin, Noémie; Fotso, Aurélien Fotso; Fautrad, Pierre; Mas, Floriane; Alessi, Marie-Christine; Riteau, Béatrice

    2017-07-01

    Influenza viruses are one of the most important respiratory pathogens worldwide, causing both epidemic and pandemic infections. The aim of the study was to evaluate the effect of FPR2 antagonists PBP10 and BOC2 on influenza virus replication. We determined that these molecules exhibit antiviral effects against influenza A (H1N1, H3N2, H6N2) and B viruses. FPR2 antagonists used in combination with oseltamivir showed additive antiviral effects. Mechanistically, the antiviral effect of PBP10 and BOC2 is mediated through early inhibition of virus-induced ERK activation. Finally, our preclinical studies showed that FPR2 antagonists protected mice from lethal infections induced by influenza, both in a prophylactic and therapeutic manner. Thus, FPR2 antagonists might be explored for novel treatments against influenza. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Crystal structure of human glycine receptor-α3 bound to antagonist strychnine.

    PubMed

    Huang, Xin; Chen, Hao; Michelsen, Klaus; Schneider, Stephen; Shaffer, Paul L

    2015-10-08

    Neurotransmitter-gated ion channels of the Cys-loop receptor family are essential mediators of fast neurotransmission throughout the nervous system and are implicated in many neurological disorders. Available X-ray structures of prokaryotic and eukaryotic Cys-loop receptors provide tremendous insights into the binding of agonists, the subsequent opening of the ion channel, and the mechanism of channel activation. Yet the mechanism of inactivation by antagonists remains unknown. Here we present a 3.0 Å X-ray structure of the human glycine receptor-α3 homopentamer in complex with a high affinity, high-specificity antagonist, strychnine. Our structure allows us to explore in detail the molecular recognition of antagonists. Comparisons with previous structures reveal a mechanism for antagonist-induced inactivation of Cys-loop receptors, involving an expansion of the orthosteric binding site in the extracellular domain that is coupled to closure of the ion pore in the transmembrane domain.

  14. Antagonist wear of monolithic zirconia crowns after 2 years.

    PubMed

    Lohbauer, Ulrich; Reich, Sven

    2017-05-01

    The aim of this study was to evaluate the amount of wear on the antagonist occlusal surfaces of clinically placed monolithic zirconia premolar and molar crowns (LAVA Plus, 3M ESPE). Fourteen in situ monolithic zirconia crowns and their opposing antagonists (n = 26) are the subject of an ongoing clinical trial and have been clinically examined at baseline and after 24 months. Silicone impressions were taken and epoxy replicas produced for qualitative SEM analysis and quantitative analysis using optical profilometry. Based on the baseline replicas, the follow-up situation has been scanned and digitally matched with the initial topography in order to calculate the mean volume loss (in mm 3 ) as well as the mean maximum vertical loss (in mm) after 2 years in service. The mean volume loss for enamel antagonist contacts (n = 7) was measured to 0.361 mm 3 and the mean of the maximum vertical loss to 0.204 mm. The mean volume loss for pure ceramic contacts (n = 10) was measured to 0.333 mm 3 and the mean of the maximum vertical loss to 0.145 mm. The wear rates on enamel contacts were not significantly different from those measured on ceramic antagonists. Based on the limitations of this study, it can be concluded for the monolithic zirconia material LAVA Plus that the measured wear rates are in consensus with other in vivo studies on ceramic restorations. Further, that no significant difference was found between natural enamel antagonists and ceramic restorations as antagonists. The monolithic zirconia restorations do not seem to be affected by wear within the first 2 years. The monolithic zirconia crowns (LAVA Plus) show acceptable antagonist wear rates after 2 years in situ, regardless of natural enamel or ceramics as antagonist materials.

  15. The Effect of Sympathetic Antagonists on the Antidepressant Action of Alprazolam

    PubMed Central

    Al-Tubuly, RA; Aburawi, SM; Alghzewi, EA; Gorash, ZM; Errwami, S

    2008-01-01

    Alprazolam is an anti-anxiety drug shown to be effective in the treatment of depression. In this study, the effect of sympathetic receptor antagonists on alprazolam–induced antidepressant action was studied using a mouse model of forced swimming behavioral despair. The interaction of three sympathetic receptor antagonists with benzodiazepines, which may impact the clinical use of alprazolam, was also studied. Behavioral despair was examined in six groups of albino mice. Drugs were administered intraperitoneally. The control group received only a single dose of 1% Tween 80. The second group received a single dose of alprazolam, and the third group received an antagonist followed by alprazolam. The fourth group was treated with imipramine, and the fifth group received an antagonist followed by imipramine. The sixth group was treated with a single dose of an antagonist alone (atenolol, a β1-selective adrenoceptor antagonist; propranolol, a non selective β-adrenoceptor antagonist; and prazocin, an α1-adrenoceptor antagonist). Results confirmed the antidepressant action of alprazolam and imipramine. Prazocin treatment alone produced depression, but it significantly potentiated the antidepressant actions of imipramine and alprazolam. Atenolol alone produced an antidepressant effect and potentiated the antidepressant action of alprazolam. Propranolol treatment alone produced depression, and antagonized the effects of alprazolam and imipramine, even producing depression in combined treatments.In conclusion, our results reveal that alprazolam may produce antidepressant effects through the release of noradrenaline, which stimulates β2 receptors to produce an antidepressant action. Imipramine may act by activating β2 receptors by blocking or down-regulating β1 receptors. PMID:21499463

  16. Characterization and bioactivity of novel calcium antagonists - N-methoxy-benzyl haloperidol quaternary ammonium salt

    PubMed Central

    Chen, Yi-Cun; Zhu, Wei; Zhong, Shu-Ping; Zheng, Fu-Chun; Gao, Fen-Fei; Zhang, Yan-Mei; Xu, Han; Zheng, Yan-Shan; Shi, Gang-Gang

    2015-01-01

    BACKGROUND AND PURPOSE Calcium antagonists play an important role in clinical practice. However, most of them have serious side effects. We have synthesized a series of novel calcium antagonists, quaternary ammonium salt derivatives of haloperidol with N-p-methoxybenzyl (X1), N-m-methoxybenzyl (X2) and N-o-methoxybenzyl (X3) groups. The objective of this study was to investigate the bioactivity of these novel calcium antagonists, especially the vasodilation activity and cardiac side-effects. The possible working mechanisms of these haloperidol derivatives were also explored. EXPERIMENTAL APPROACH Novel calcium antagonists were synthesized by amination. Compounds were screened for their activity of vasodilation on isolated thoracic aortic ring of rats. Their cardiac side effects were explored. The patch-clamp, confocal laser microscopy and the computer-fitting molecular docking experiments were employed to investigate the possible working mechanisms of these calcium antagonists. RESULTS The novel calcium antagonists, X1, X2 and X3 showed stronger vasodilation effect and less cardiac side effect than that of classical calcium antagonists. They blocked L-type calcium channels with an potent effect order of X1 > X2 > X3. Consistently, X1, X2 and X3 interacted with different regions of Ca2+-CaM-CaV1.2 with an affinity order of X1 > X2 > X3. CONCLUSIONS The new halopedidol derivatives X1, X2 and X3 are novel calcium antagonists with stronger vasodilation effect and less cardiac side effect. They could have wide clinical application. PMID:26544729

  17. CCR5 receptor antagonists: discovery and SAR study of guanylhydrazone derivatives.

    PubMed

    Wei, Robert G; Arnaiz, Damian O; Chou, Yuo-Ling; Davey, Dave; Dunning, Laura; Lee, Wheeseong; Lu, Shou-Fu; Onuffer, James; Ye, Bin; Phillips, Gary

    2007-01-01

    High throughput screening (HTS) led to the identification of the guanylhydrazone of 2-(4-chlorobenzyloxy)-5-bromobenzaldehyde as a CCR5 receptor antagonist. Initial modifications of the guanylhydrazone series indicated that substitution of the benzyl group at the para-position was well tolerated. Substitution at the 5-position of the central phenyl ring was critical for potency. Replacement of the guanylhydrazone group led to the discovery of a novel series of CCR5 antagonists.

  18. Melanocortin Antagonist Tetrapeptides with Minimal Agonist Activity at the Mouse Melanocortin-3 Receptor

    PubMed Central

    2014-01-01

    The melanocortin system regulates many important functions in the body. There are five melanocortin G protein-coupled receptor subtypes known to date. Herein, we report a structure–activity relationship (SAR) study of a tetrapeptide lead discovered through a double substitution strategy at the melanocortin core His-Phe-Arg-Trp sequence. Several compounds were identified with micromolar agonist activity at the mouse melanocortin-1 (mMC1R) and mouse melanocortin-5 receptor (mMC5R) subtypes, weak antagonist activity at the mouse melanocortin-3 receptor (mMC3R), and potent antagonist activity at the mouse melanocortin-4 receptor (mMC4R). Two compounds (2 and 3) were nanomolar mMC4R antagonists with no mMC3R antagonist activity observed. Additionally, we identified three tetrapeptide MC3R antagonists (1, 6, and 7) that possess minimal mMC3R agonist activity only at 100 μM, not commonly observed for mMC3R/mMC4R antagonists. These novel molecular templates have the potential as molecular probes to better differentiate the roles of the centrally expressed MC3 and MC4 receptors. PMID:25699138

  19. Meiotic drive influences the outcome of sexually antagonistic selection at a linked locus.

    PubMed

    Patten, M M

    2014-11-01

    Most meiotic drivers, such as the t-haplotype in Mus and the segregation distorter (SD) in Drosophila, act in a sex-specific manner, gaining a transmission advantage through one sex although suffering only the fitness costs associated with the driver in the other. Their inheritance is thus more likely through one of the two sexes, a property they share with sexually antagonistic alleles. Previous theory has shown that pairs of linked loci segregating for sexually antagonistic alleles are more likely to remain polymorphic and that linkage disequilibrium accrues between them. I probe this similarity between drive and sexual antagonism and examine the evolution of chromosomes experiencing these selection pressures simultaneously. Reminiscent of previous theory, I find that: the opportunity for polymorphism increases for a sexually antagonistic locus that is physically linked to a driving locus; the opportunity for polymorphism at a driving locus also increases when linked to a sexually antagonistic locus; and stable linkage disequilibrium accompanies any polymorphic equilibrium. Additionally, I find that drive at a linked locus favours the fixation of sexually antagonistic alleles that benefit the sex in which drive occurs. Further, I show that under certain conditions reduced recombination between these two loci is selectively favoured. These theoretical results provide clear, testable predictions about the nature of sexually antagonistic variation on driving chromosomes and have implications for the evolution of genomic architecture. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  20. Isolation and characterization of a novel analyte from Bacillus subtilis SC-8 antagonistic to Bacillus cereus.

    PubMed

    Lee, Nam Keun; Yeo, In-Cheol; Park, Joung Whan; Kang, Byung-Sun; Hahm, Young Tae

    2010-09-01

    In this study, an effective substance was isolated from Bacillus subtilis SC-8, which was obtained from traditionally fermented soybean paste, cheonggukjang. The substance was purified by HPLC, and its properties were analyzed. It had an adequate antagonistic effect on Bacilluscereus, and its spectrum of activity was narrow. When tested on several gram-negative and gram-positive foodborne pathogenic bacteria such as Salmonella enterica, Salmonella enteritidis, Staphylococcus aureus, and Listeria monocytogenes, no antagonistic effect was observed. Applying the derivative from B. subtilis SC-8 within the same genus did not inhibit the growth of major soybean-fermenting bacteria such as Bacillus subtilis, Bacillus licheniformis, and Bacillus amyloquefaciens. The range of pH stability of the purified antagonistic substance was wide (from 4.0 to >10.0), and the substance was thermally stable up to 60 degrees C. In the various enzyme treatments, the antagonistic activity of the purified substance was reduced with proteinase K, protease, and lipase; its activity was partially destroyed with esterase. Spores of B. cereus did not grow at all in the presence of 5mug/mL of the purified antagonistic substance. The isolated antagonistic substance was thought to be an antibiotic-like lipopeptidal compound and was tentatively named BSAP-254 because it absorbed to UV radiation at 254nm. Copyright 2010 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  1. Anti-idiotypic antibody: A new strategy for the development of a growth hormone receptor antagonist.

    PubMed

    Lan, Hainan; Zheng, Xin; Khan, Muhammad Akram; Li, Steven

    2015-11-01

    In general, traditional growth hormone receptor antagonist can be divided into two major classes: growth hormone (GH) analogues and anti-growth hormone receptor (GHR) antibodies. Herein, we tried to explore a new class of growth hormone receptor (GHR) antagonist that may have potential advantages over the traditional antagonists. For this, we developed a monoclonal anti-idiotypic antibody growth hormone, termed CG-86. A series of experiments were conducted to characterize and evaluate this antibody, and the results from a competitive receptor-binding assay, Enzyme Linked Immunosorbent Assays (ELISA) and epitope mapping demonstrate that CG-86 behaved as a typical Ab2β. Next, we examined its antagonistic activity using in vitro cell models, and the results showed that CG-86 could effectively inhibit growth hormone receptor-mediated signalling and effectively inhibit growth hormone-induced Ba/F3-GHR638 proliferation. In summary, these studies show that an anti-idiotypic antibody (CG-86) has promise as a novel growth hormone receptor antagonist. Furthermore, the current findings also suggest that anti-idiotypic antibody may represent a novel strategy to produce a new class of growth hormone receptor antagonist, and this strategy may be applied with other cytokines or growth factors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Molecular Gymnastics: Mechanisms of HIV-1 Resistance to CCR5 Antagonists and Impact on Virus Phenotypes.

    PubMed

    Roche, Michael; Borm, Katharina; Flynn, Jacqueline K; Lewin, Sharon R; Churchill, Melissa J; Gorry, Paul R

    2016-01-01

    Human immunodeficiency virus type 1 (HIV-1) enters host cells through the binding of its envelope glycoproteins (Env) to the host cell receptor CD4 and then subsequent binding to a chemokine coreceptor, either CCR5 or CXCR4. CCR5 antagonists are a relatively recent class addition to the armamentarium of anti-HIV-1 drugs. These compounds act by binding to a hydrophobic pocket formed by the transmembrane helices of CCR5 and altering the conformation of the extracellular domains, such that they are no longer recognized by Env. Maraviroc is the first drug within this class to be licenced for use in HIV-1 therapy regimens. HIV resistance to CCR5 antagonists occurs either through outgrowth of pre-existing CXCR4-using viruses, or through acquisition of the ability of CCR5-using HIV-1 to use the antagonist bound form of CCR5. In the latter scenario, the mechanism underlying resistance is through complex alterations in the way that resistant Envs engage CCR5. These significant changes are unlikely to occur without consequence to the viral entry phenotype and may also open up new avenues to target CCR5 antagonist resistant viruses. This review discusses the mechanism of action of CCR5 antagonists, how HIV resistance to CCR5 antagonists occurs, and the subsequent effects on Env function.

  3. Pseudomonas orientalis F9: A Potent Antagonist against Phytopathogens with Phytotoxic Effect in the Apple Flower

    PubMed Central

    Zengerer, Veronika; Schmid, Michael; Bieri, Marco; Müller, Denise C.; Remus-Emsermann, Mitja N. P.; Ahrens, Christian H.; Pelludat, Cosima

    2018-01-01

    In light of public concerns over the use of pesticides and antibiotics in plant protection and the subsequent selection for spread of resistant bacteria in the environment, it is inevitable to broaden our knowledge about viable alternatives, such as natural antagonists and their mode of action. The genus Pseudomonas is known for its metabolic versatility and genetic plasticity, encompassing pathogens as well as antagonists. We characterized strain Pseudomonas orientalis F9, an isolate from apple flowers in a Swiss orchard, and determined its antagonistic activity against several phytopathogenic bacteria, in particular Erwinia amylovora, the causal agent of fire blight. P. orientalis F9 displayed antagonistic activity against a broad suite of phytopathogenic bacteria in the in vitro tests. The promising results from this analysis led to an ex vivo assay with E. amylovora CFBP1430Rif and P. orientalis F9 infected detached apple flowers. F9 diminished the fire blight pathogen in the flowers but also revealed phytotoxic traits. The experimental results were discussed in light of the complete genome sequence of F9, which revealed the strain to carry phenazine genes. Phenazines are known to contribute to antagonistic activity of bacterial strains against soil pathogens. When tested in the cress assay with Pythium ultimum as pathogen, F9 showed results comparable to the known antagonist P. protegens CHA0. PMID:29479340

  4. [The antagonistic properties of microaerophilic bacteria isolated from the human and mink digestive tracts].

    PubMed

    Sudenko, V I; Groma, L I; Podgorskiĭ, V S

    1996-01-01

    Study of antagonistic properties of microaerophilic bacteria isolated from human and mink gastroenteric tract have helped to establish differences in species composition, quantity and level of antagonistic activity of the studied microorganisms in respect to pathogenic microflora. It is shown that lactic acid bacteria identified as Lactobacillus fermentum and L. reuteri prevail among the strains isolated from the stomach and thin intestine of minks kept in the 30-km zone of Chernobyl NPP. Species composition of microaerophilic bacteria isolated from the digestive tract of the control minks is more variable. Antagonistically active bifidobacteria prevail in large intestine of experimental and control animals. Strains of lactic acid bacteria with the expressed antagonistic activity belonging to L. bavaricus, L. reuteri, L. coryniformis and L. maltaromicus have been found parallel with such known producers of antibiotic-like substances as L. fermentum. L. acidophilum. Streptococcus faecalis and bifidobacteria. L. maltaromicus most frequently occurred among antagonistically active strains revealed in feces of people which stayed in the zone of liquidation of the Chernobyl accident. Microaerophilic strains of bacteria (lactic acid, bifidobacteria and enterococci) manifest the expressed antagonistic activity connected with the capacity to not only acid formation but also to accumulation of antibiotic products of unknown nature. A strain of lactic acid bacteria L. fermentum 91 has been isolated from the contents of human gastroenteric tract. These bacteria are distinguished by most expressed and stable antagonism and characterized by the lack of pathogenicity in respect of albino mice that may be used to raise the microorganism resistance to gastric diseases.

  5. Design of novel neurokinin 1 receptor antagonists based on conformationally constrained aromatic amino acids and discovery of a potent chimeric opioid agonist-neurokinin 1 receptor antagonist.

    PubMed

    Ballet, Steven; Feytens, Debby; Buysse, Koen; Chung, Nga N; Lemieux, Carole; Tumati, Suneeta; Keresztes, Attila; Van Duppen, Joost; Lai, Josephine; Varga, Eva; Porreca, Frank; Schiller, Peter W; Vanden Broeck, Jozef; Tourwé, Dirk

    2011-04-14

    A screening of conformationally constrained aromatic amino acids as base cores for the preparation of new NK1 receptor antagonists resulted in the discovery of three new NK1 receptor antagonists, 19 [Ac-Aba-Gly-NH-3',5'-(CF(3))(2)-Bn], 20 [Ac-Aba-Gly-NMe-3',5'-(CF(3))(2)-Bn], and 23 [Ac-Tic-NMe-3',5'-(CF(3))(2)-Bn], which were able to counteract the agonist effect of substance P, the endogenous ligand of NK1R. The most active NK1 antagonist of the series, 20 [Ac-Aba-Gly-NMe-3',5'-(CF(3))(2)-Bn], was then used in the design of a novel, potent chimeric opioid agonist-NK1 receptor antagonist, 35 [Dmt-D-Arg-Aba-Gly-NMe-3',5'-(CF(3))(2)-Bn], which combines the N terminus of the established Dmt(1)-DALDA agonist opioid pharmacophore (H-Dmt-D-Arg-Phe-Lys-NH(2)) and 20, the NK1R ligand. The opioid component of the chimeric compound 35, that is, Dmt-D-Arg-Aba-Gly-NH(2) (36), also proved to be an extremely potent and balanced μ and δ opioid receptor agonist with subnanomolar binding and in vitro functional activity.

  6. Design of novel neurokinin 1 receptor antagonists based on conformationally constrained aromatic amino acids and discovery of a potent chimeric opioid agonist-neurokinin 1 receptor antagonist

    PubMed Central

    Ballet, Steven; Feytens, Debby; Buysse, Koen; Chung, Nga N.; Lemieux, Carole; Tumati, Suneeta; Keresztes, Attila; Van Duppen, Joost; Lai, Josephine; Varga, Eva; Porreca, Frank; Schiller, Peter W.; Broeck, Jozef Vanden; Tourwé, Dirk

    2011-01-01

    A screening of conformationally constrained aromatic amino acids as base cores for the preparation of new NK1 receptor antagonists resulted in the discovery of three new NK1 receptor antagonists, 19 [Ac-Aba-Gly-NH-3′,5′-(CF3)2-Bn], 20 [Ac-Aba-Gly-NMe-3′,5′-(CF3)2-Bn] and 23 [Ac-Tic-NMe-3′,5′-(CF3)2-Bn], which were able to counteract the agonist effect of substance P, the endogenous ligand of NK1R. The most active NK1 antagonist of the series, 20 [Ac-Aba-Gly-NMe-3′,5′-(CF3)2-Bn], was then used in the design of a novel, potent chimeric opioid agonist-NK1 receptor antagonist, 35 [Dmt-D-Arg-Aba-Gly-NMe-3′,5′-(CF3)2-Bn], which combines the N-terminus of the established Dmt1-DALDA agonist opioid pharmacophore (H-Dmt-D-Arg-Phe-Lys-NH2) and 20, the NK1R ligand. The opioid component of the chimeric compound 35, i.e. Dmt-D-Arg-Aba-Gly-NH2 36, also proved to be an extremely potent and balanced μ- and δ opioid receptor agonist with subnanomolar binding and in vitro functional activity. PMID:21413804

  7. Targeting Renal Cell Carcinoma with a HIF-2 antagonist

    PubMed Central

    Chen, Wenfang; Hill, Haley; Christie, Alana; Kim, Min Soo; Holloman, Eboni; Pavia-Jimenez, Andrea; Homayoun, Farrah; Ma, Yuanqing; Patel, Nirav; Yell, Paul; Hao, Guiyang; Yousuf, Qurratulain; Joyce, Allison; Pedrosa, Ivan; Geiger, Heather; Zhang, He; Chang, Jenny; Gardner, Kevin H.; Bruick, Richard K.; Reeves, Catherine; Hwang, Tae Hyun; Courtney, Kevin; Frenkel, Eugene; Sun, Xiankai; Zojwalla, Naseem; Wong, Tai; Rizzi, James P.; Wallace, Eli M.; Josey, John A.; Xie, Yang; Xie, Xian-Jin; Kapur, Payal; McKay, Renée M.; Brugarolas, James

    2016-01-01

    Clear cell Renal Cell Carcinoma (ccRCC) is characterized by VHL inactivation1,2. Because no other gene is mutated as frequently, and VHL mutations are truncal3, VHL inactivation is regarded as the governing event4. VHL loss activates HIF-2, and constitutive HIF-2 restores tumorigenesis in VHL-reconstituted ccRCC cells5. HIF-2 is implicated in angiogenesis and multiple other processes6–9, but angiogenesis is the main target of drugs like sunitinib10. HIF-2, a transcription factor, has been regarded as undruggable11. A structure-based design approach identified a selective HIF-2 antagonist (PT2399) that we evaluate using a tumorgraft (TG)/PDX platform12,13. PT2399 dissociated HIF-2 (an obligatory heterodimer [HIF-2α/HIF-1β])14 in human ccRCC suppressing tumorigenesis in 56% (10/18) lines. PT2399 had greater activity than sunitinib, was active in sunitinib-progressing tumors, and was better tolerated. Unexpectedly, some VHL-mutant ccRCCs were resistant. Resistance occurred despite HIF-2 dissociation in tumors and evidence of Hif-2 inhibition in the mouse as determined by suppression of circulating erythropoietin, a HIF-2 target15 and possible pharmacodynamic marker. We identified a HIF-2-dependent gene signature in sensitive tumors. Illustrating drug specificity, gene expression was largely unaffected by PT2399 in resistant tumors. Sensitive tumors exhibited a distinguishing gene expression signature, and generally higher HIF-2α levels. Prolonged PT2399 treatment led to resistance. We identified a binding site and second site suppressor mutation in HIF-2α and HIF-1β respectively. Both mutations preserved HIF-2 dimers despite treatment with PT2399. Finally, an extensively pretreated patient with a sensitive TG had disease control for >11 months with the close analogue PT2385. We validate HIF-2 as a target in ccRCC, show that some ccRCC are, unexpectedly, HIF-2 independent, and set the stage for biomarker-driven clinical trials. PMID:27595394

  8. Targeting renal cell carcinoma with a HIF-2 antagonist.

    PubMed

    Chen, Wenfang; Hill, Haley; Christie, Alana; Kim, Min Soo; Holloman, Eboni; Pavia-Jimenez, Andrea; Homayoun, Farrah; Ma, Yuanqing; Patel, Nirav; Yell, Paul; Hao, Guiyang; Yousuf, Qurratulain; Joyce, Allison; Pedrosa, Ivan; Geiger, Heather; Zhang, He; Chang, Jenny; Gardner, Kevin H; Bruick, Richard K; Reeves, Catherine; Hwang, Tae Hyun; Courtney, Kevin; Frenkel, Eugene; Sun, Xiankai; Zojwalla, Naseem; Wong, Tai; Rizzi, James P; Wallace, Eli M; Josey, John A; Xie, Yang; Xie, Xian-Jin; Kapur, Payal; McKay, Renée M; Brugarolas, James

    2016-11-03

    Clear cell renal cell carcinoma (ccRCC) is characterized by inactivation of the von Hippel-Lindau tumour suppressor gene (VHL). Because no other gene is mutated as frequently in ccRCC and VHL mutations are truncal, VHL inactivation is regarded as the governing event. VHL loss activates the HIF-2 transcription factor, and constitutive HIF-2 activity restores tumorigenesis in VHL-reconstituted ccRCC cells. HIF-2 has been implicated in angiogenesis and multiple other processes, but angiogenesis is the main target of drugs such as the tyrosine kinase inhibitor sunitinib. HIF-2 has been regarded as undruggable. Here we use a tumourgraft/patient-derived xenograft platform to evaluate PT2399, a selective HIF-2 antagonist that was identified using a structure-based design approach. PT2399 dissociated HIF-2 (an obligatory heterodimer of HIF-2α-HIF-1β) in human ccRCC cells and suppressed tumorigenesis in 56% (10 out of 18) of such lines. PT2399 had greater activity than sunitinib, was active in sunitinib-progressing tumours, and was better tolerated. Unexpectedly, some VHL-mutant ccRCCs were resistant to PT2399. Resistance occurred despite HIF-2 dissociation in tumours and evidence of Hif-2 inhibition in the mouse, as determined by suppression of circulating erythropoietin, a HIF-2 target and possible pharmacodynamic marker. We identified a HIF-2-dependent gene signature in sensitive tumours. Gene expression was largely unaffected by PT2399 in resistant tumours, illustrating the specificity of the drug. Sensitive tumours exhibited a distinguishing gene expression signature and generally higher levels of HIF-2α. Prolonged PT2399 treatment led to resistance. We identified binding site and second site suppressor mutations in HIF-2α and HIF-1β, respectively. Both mutations preserved HIF-2 dimers despite treatment with PT2399. Finally, an extensively pretreated patient whose tumour had given rise to a sensitive tumourgraft showed disease control for more than 11 months when

  9. Mineralocorticoid receptor antagonists in kidney transplantation: time to consider?

    PubMed

    Girerd, Sophie; Jaisser, Frédéric

    2018-04-17

    Although patient survival is significantly improved by kidney transplantation (KT) in comparison with dialysis, it remains significantly lower than that observed in the general population. Graft function is one of the major determinants of patient survival after KT. Mineralocorticoid receptor antagonists (MRAs) could be of particular interest in this population to improve graft function and treat or prevent cardiovascular (CV) complications. In KT, ischaemia/reperfusion injury is a major factor involved in delayed graft function, which is often associated with inferior long-term graft survival. Preclinical studies suggest that MRAs may prevent ischaemia/reperfusion-related lesions in addition to having a protective effect in preventing calcineurin inhibitor-induced nephrotoxicity. Clinical data also support the anti-proteinuric effect of MRAs in chronic kidney disease (CKD). Taken together, MRAs may hence be of particular benefit in improving short- and long-term graft function. Numerous randomized controlled trials (RCTs) have shown the efficacy of MRAs in both heart failure and resistant hypertension. As these comorbidities are frequent in kidney transplant recipients before transplantation or during follow-up, MRAs could represent a useful therapeutic option in those with mild renal function impairment. However, CKD patients are under-represented in RCTs and the CV effects of MRAs in kidney transplant recipients have yet to be specifically assessed in large-scale trials. Available evidence indicates a good safety profile for MRAs in patients with a glomerular filtration rate (GFR) >30 mL/min/1.73 m2. However, as for all patients prescribed an MRA, creatinine and potassium should also be closely monitored following MRA initiation in kidney transplant patients. Given the current evidence suggesting that MRAs prevent ischaemia/reperfusion-related lesions and calcineurin inhibitor-induced nephrotoxicity in kidney transplant recipients as well as CV events in

  10. Implementation of a Fluorescence-Based Screening Assay Identifies Histamine H3 Receptor Antagonists Clobenpropit and Iodophenpropit as Subunit-Selective N-Methyl-d-Aspartate Receptor Antagonists

    PubMed Central

    Hansen, Kasper B.; Mullasseril, Praseeda; Dawit, Sara; Kurtkaya, Natalie L.; Yuan, Hongjie; Vance, Katie M.; Orr, Anna G.; Kvist, Trine; Ogden, Kevin K.; Le, Phuong; Vellano, Kimberly M.; Lewis, Iestyn; Kurtkaya, Serdar; Du, Yuhong; Qui, Min; Murphy, T. J.; Snyder, James P.; Bräuner-Osborne, Hans

    2010-01-01

    N-Methyl-d-aspartate (NMDA) receptors are ligand-gated ion channels that mediate a slow, Ca2+-permeable component of excitatory synaptic transmission in the central nervous system and play a pivotal role in synaptic plasticity, neuronal development, and several neurological diseases. We describe a fluorescence-based assay that measures NMDA receptor-mediated changes in intracellular calcium in a BHK-21 cell line stably expressing NMDA receptor NR2D with NR1 under the control of a tetracycline-inducible promoter (Tet-On). The assay selectively identifies allosteric modulators by using supramaximal concentrations of glutamate and glycine to minimize detection of competitive antagonists. The assay is validated by successfully identifying known noncompetitive, but not competitive NMDA receptor antagonists among 1800 screened compounds from two small focused libraries, including the commercially available library of pharmacologically active compounds. Hits from the primary screen are validated through a secondary screen that used two-electrode voltage-clamp recordings on recombinant NMDA receptors expressed in Xenopus laevis oocytes. This strategy identified several novel modulators of NMDA receptor function, including the histamine H3 receptor antagonists clobenpropit and iodophenpropit, as well as the vanilloid receptor transient receptor potential cation channel, subfamily V, member 1 (TRPV1) antagonist capsazepine. These compounds are noncompetitive antagonists and the histamine H3 receptor ligand showed submicromolar potency at NR1/NR2B NMDA receptors, which raises the possibility that compounds can be developed that act with high potency on both glutamate and histamine receptor systems simultaneously. Furthermore, it is possible that some actions attributed to histamine H3 receptor inhibition in vivo may also involve NMDA receptor antagonism. PMID:20197375

  11. Wear of ceramic and antagonist--a systematic evaluation of influencing factors in vitro.

    PubMed

    Heintze, S D; Cavalleri, A; Forjanic, M; Zellweger, G; Rousson, V

    2008-04-01

    (1) To systematically review the existing literature on in vitro assessments of antagonist wear of ceramic materials; (2) To systematically evaluate possible influencing factors on material and antagonist wear of ceramic specimens. The database MEDLINE was searched with the terms "enamel," "wear" and "antagonist." The selected studies were analyzed with regard to wear parameters, type of antagonist and outcome. In the laboratory study, three ceramic materials were selected with different compositions and physical properties: IPS d.SIGN low-fusing metal ceramic, IPS Empress leucite ceramic, e.max Press lithium disilicate ceramic. These materials were subjected to the Ivoclar wear method (Willytec chewing simulator, 120,000cycles, 5kg weight) by systematically modifying the following variables which resulted in 36 tests with 8 specimens in each group: (1) configuration (flat, crown specimen), (2) surface treatment (polish, glaze), (3) type of antagonist (ceramic, two types of enamel stylus). Furthermore, the enamel styluses were cut to measure the enamel thickness and cusp width. Wear of both the material and the antagonist was quantified by scanning plaster replicas of the specimens with a laser scanner (etkon es1) and matching baseline and follow-up data with the Match 3D software (Willytec). The data were log-transformed to stabilize the variance and achieve near normality. To test the influence of specific test parameters, a four-way ANOVA with post hoc tests and Bonferroni correction was applied. The systematic review revealed 20 in vitro studies in which a material and the antagonist wear of the same material was examined. However, the results were inconsistent mainly due to the fact that the test parameters differed widely. Most studies used prepared enamel from extracted molars as the antagonist and flat polished ceramic specimens. The test chamber was filled with water and some sort of sliding movement was integrated in the wear generating process. However

  12. Inhibition of rabbit platelet activation in vitro by antagonists of platelet-activating factor (PAF)

    SciTech Connect

    Cox, C.P.; Wood, K.L.

    1986-03-05

    The authors used washed, (/sup 3/H)serotonin-labeled rabbit platelets to study the in vitro aggregation and secretion responses induced by graded doses of PAF in the presence or absence of specific antagonists of PAF. These antagonists included CV-3988, L-652,731, triazolam and alprazolam. Platelets were pretreated with either an antagonist or the appropriate diluent for 60 sec prior to the addition of PAF (2 x 10/sup -10/ to 2 x 10/sup -7/ M). Aggregation was monitored continuously and recorded as the height of the aggregation tracing at 60 sec post-PAF. Secretion of (/sup 3/H)-serotonin was measured in a sample of the plateletsmore » removed at 60 sec post-PAF. When 2 x 10/sup -10/ M PAF was used as the stimulus, the concentration of antagonist needed for 50% inhibition (IC/sub 50/) of secretion was obtained at 0.05 ..mu..M, 0.15 ..mu..M, 0.6 ..mu..M and 2.5 ..mu..M, respectively, for L-652,731, CV-3988, triazolam and alprazolam. The corresponding IC/sub 50/ for aggregation was obtained at 0.2 ..mu..M, 0.1 ..mu..M, 1.5 ..mu..M and 6.5 ..mu..M, respectively. The inhibitory effects of these antagonists could be overcome by increasing the dose of PAF used. Although all of the antagonists were capable of completely inhibiting platelet aggregation and secretion, L-652,731 was the most potent PAF antagonist on a molar basis.« less

  13. From Chemotherapy-Induced Emesis to Neuroprotection: Therapeutic Opportunities for 5-HT3 Receptor Antagonists.

    PubMed

    Fakhfouri, Gohar; Mousavizadeh, Kazem; Mehr, Sharam Ejtemaei; Dehpour, Ahmad Reza; Zirak, Mohammad Reza; Ghia, Jean-Eric; Rahimian, Reza

    2015-12-01

    5-HT3 receptor antagonists are extensively used as efficacious agents in counteracting chemotherapy-induced emesis. Recent investigations have shed light on other potential effects (analgesic, anxiolytic, and anti-psychotic). Some studies have reported neuroprotective properties for the 5-HT3 receptor antagonists in vitro and in vivo. When administered to Aβ-challenged rat cortical neurons, 5-HT3 receptor antagonists substantially abated apoptosis, elevation of cytosolic Ca(2), glutamate release, reactive oxygen species (ROS) generation, and caspase-3 activity. In addition, in vivo studies show that 5-HT3 receptor antagonists possess, alongside their anti-emetic effects, notable immunomodulatory properties in CNS. We found that pretreatment with tropisetron significantly improved neurological deficits and diminished leukocyte transmigration into the brain, TNF-α level, and brain infarction in a murine model of embolic stroke. Our recent investigation revealed that tropisetron protects against Aβ-induced neurotoxicity in vivo through both 5-HT3 receptor-dependent and -independent pathways. Tropisetron, in vitro, was found to be an efficacious inhibitor of the signaling pathway leading to the activation of pro-inflammatory NF-κB, a transcription factor pivotal to the upregulation of several neuroinflammatory mediators in brain. This mini review summarizes novel evidence concerning effects of 5-HT3 antagonists and their possible mechanisms of action in ameliorating neurodegenerative diseases including Alzheimer, multiple sclerosis, and stroke. Further, we discuss some newly synthesized 5-HT3 receptor antagonists with dual properties of 5-HT3 receptor blockade/alpha-7 nicotinic receptor activator and their potential in management of memory impairment. Since 5-HT3 receptor antagonists possess a large therapeutic window, they can constitute a scaffold for design and synthesis of new neuroprotective medications.

  14. Oxytocin and Vasopressin Agonists and Antagonists as Research Tools and Potential Therapeutics

    PubMed Central

    Manning, M; Misicka, A; Olma, A; Bankowski, K; Stoev, S; Chini, B; Durroux, T; Mouillac, B; Corbani, M; Guillon, G

    2012-01-01

    We recently reviewed the status of peptide and nonpeptide agonists and antagonists for the V1a, V1b and V2 receptors for arginine vasopressin (AVP) and the oxytocin receptor for oxytocin (OT). In the present review, we update the status of peptides and nonpeptides as: (i) research tools and (ii) therapeutic agents. We also present our recent findings on the design of fluorescent ligands for V1b receptor localisation and for OT receptor dimerisation. We note the exciting discoveries regarding two novel naturally occurring analogues of OT. Recent reports of a selective VP V1a agonist and a selective OT agonist point to the continued therapeutic potential of peptides in this field. To date, only two nonpeptides, the V2/V1a antagonist, conivaptan and the V2 antagonist tolvaptan have received Food and Drug Administration approval for clinical use. The development of nonpeptide AVP V1a, V1b and V2 antagonists and OT agonists and antagonists has recently been abandoned by Merck, Sanofi and Pfizer. A promising OT antagonist, Retosiban, developed at Glaxo SmithKline is currently in a Phase II clinical trial for the prevention of premature labour. A number of the nonpeptide ligands that were not successful in clinical trials are proving to be valuable as research tools. Peptide agonists and antagonists continue to be very widely used as research tools in this field. In this regard, we present receptor data on some of the most widely used peptide and nonpeptide ligands, as a guide for their use, especially with regard to receptor selectivity and species differences. PMID:22375852

  15. SSTR-Mediated Imaging in Breast Cancer: Is There a Role for Radiolabeled Somatostatin Receptor Antagonists?

    PubMed

    Dalm, Simone U; Haeck, Joost; Doeswijk, Gabriela N; de Blois, Erik; de Jong, Marion; van Deurzen, Carolien H M

    2017-10-01

    Recent studies have shown enhanced tumor targeting by novel somatostatin receptor (SSTR) antagonists compared with clinically widely used agonists. However, these results have been obtained mostly in neuroendocrine tumors, and only limited data are available for cancer types with lower SSTR expression, including breast cancer (BC). To date, two studies have reported higher binding of the antagonist than the agonist in BC, but in both studies only a limited number of cases were evaluated. In this preclinical study, we further investigated whether the application of an SSTR antagonist can improve SSTR-mediated BC imaging in a large panel of BC specimens. We also generated an in vivo BC mouse model and performed SPECT/MRI and biodistribution studies. Methods: Binding of 111 In-DOTA-Tyr 3 -octreotate (SSTR agonist) and 111 In-DOTA-JR11 (SSTR antagonist) to 40 human BC specimens was compared using in vitro autoradiography. SSTR2 immunostaining was performed to confirm SSTR2 expression of the tumor cells. Furthermore, binding of the radiolabeled SSTR agonist and antagonist was analyzed in tissue material from 6 patient-derived xenografts. One patient-derived xenograft, the estrogen receptor-positive model T126, was chosen to generate in vivo mouse models containing orthotopic breast tumors for in vivo SPECT/MRI and biodistribution studies after injection with 177 Lu-DOTA-Tyr 3 -octreotate or 177 Lu-DOTA-JR11. Results: 111 In-DOTA-JR11 binding to human BC tissue was significantly higher than 111 In-DOTA-Tyr 3 -octreotate binding ( P < 0.001). The median ratio of antagonist binding versus agonist binding was 3.39 (interquartile range, 2-5). SSTR2 immunostaining confirmed SSTR2 expression on the tumor cells. SPECT/MRI of the mouse model found better tumor visualization with the antagonist. This result was in line with the significantly higher tumor uptake of the radiolabeled antagonist than of the agonist as measured in biodistribution studies 285 min after radiotracer

  16. Design and Synthesis of Benzimidazoles As Novel Corticotropin-Releasing Factor 1 Receptor Antagonists.

    PubMed

    Mochizuki, Michiyo; Kori, Masakuni; Kobayashi, Katsumi; Yano, Takahiko; Sako, Yuu; Tanaka, Maiko; Kanzaki, Naoyuki; Gyorkos, Albert C; Corrette, Christopher P; Cho, Suk Young; Pratt, Scott A; Aso, Kazuyoshi

    2016-03-24

    Benzazole derivatives with a flexible aryl group bonded through a one-atom linker as a new scaffold for a corticotropin-releasing factor 1 (CRF1) receptor antagonist were designed, synthesized, and evaluated. We expected that structural diversity could be expanded beyond that of reported CRF1 receptor antagonists. In a structure-activity relationship study, 4-chloro-N(2)-(4-chloro-2-methoxy-6-methylphenyl)-1-methyl-N(7),N(7)-dipropyl-1H-benzimidazole-2,7-diamine 29g had the most potent binding activity against a human CRF1 receptor and the antagonistic activity (IC50 = 9.5 and 88 nM, respectively) without concerns regarding cytotoxicity at 30 μM. Potent CRF1 receptor-binding activity in brain in an ex vivo test and suppression of stress-induced activation of the hypothalamus-pituitary-adrenocortical (HPA) axis were also observed at 138 μmol/kg of compound 29g after oral administration in mice. Thus, the newly designed benzimidazole 29g showed in vivo CRF1 receptor antagonistic activity and good brain penetration, indicating that it is a promising lead for CRF1 receptor antagonist drug discovery research.

  17. Hypertension study in anaesthetized rabbits: protocol proposal for AT1 antagonists screening.

    PubMed

    Politi, Aggeliki P; Zervou, Maria V; Triantafyllidi, Helen; Zoumpoulakis, Panagiotis G; Mavromoustakos, Thomas M; Zoga, Anastasia A; Moutevelis-Minakakis, Panagiota; Kokotos, George; Iliodromitis, Efstathios K; Kremastinos, Dimitris Th

    2010-06-01

    The aim of this study was to establish an optimized fast and safe protocol for the pharmacological screening of AT(1) antagonists. The pharmaceutical prototype AT(1) antagonist losartan, its active metabolite EXP3174 and the synthetic compound MMK1 were analysed in order to validate the protocol. Ang II was continuously infused while the animals received the drugs in two procedures. In the post-treatment procedure drugs were administered either in a single bolus dose or in a sequential manner. When losartan was administered in a single bolus dose, efficacy was evident until the 7th min (p=0.012) whilst EXP3174 infusion extended the efficiency up to the end of the study (p=0.006). In addition, the sequential injections of losartan prolonged the inhibitory time interval until the end of the study (p=0.045). In the pre-treatment procedure, results suggested a dose-dependent inhibitory effect for both antagonists. The pressor response to Ang II was unchanged after MMK1 administration either in the post- or in the pre-treatment mode. The proposed protocol appears to be safe, simple and fast for the pharmacological screening of AT(1) antagonists and enables the evaluation of new antagonists using lower doses than any other reported in the literature.

  18. Pegylated Leptin Antagonist Is a Potent Orexigenic Agent: Preparation and Mechanism of Activity

    PubMed Central

    Elinav, Eran; Niv-Spector, Leonora; Katz, Meirav; Price, Tulin O.; Ali, Mohammed; Yacobovitz, Michal; Solomon, Gili; Reicher, Shay; Lynch, Jessica L.; Halpern, Zamir; Banks, William A.; Gertler, Arieh

    2009-01-01

    Leptin, a pleiotropic adipokine, is a central regulator of appetite and weight and a key immunomodulatory protein. Although inborn leptin deficiency causes weight gain, it is unclear whether induced leptin deficiency in adult wild-type animals would be orexigenic. Previous work with a potent competitive leptin antagonist did not induce a true metabolic state of leptin deficiency in mice because of a short circulating half-life. In this study, we increased the half-life of the leptin antagonist by pegylation, which resulted in significantly increased bioavailability and retaining of antagonistic activity. Mice administered the pegylated antagonist showed a rapid and dramatic increase in food intake with weight gain. Resulting fat was confined to the mesenteric region with no accumulation in the liver. Serum cholesterol, triglyceride, a