Sample records for acid receptor rar

  1. Adenovirus E1A functions as a cofactor for retinoic acid receptor beta (RAR beta) through direct interaction with RAR beta.

    PubMed

    Folkers, G E; van der Saag, P T

    1995-11-01

    Transcription regulation by DNA-bound activators is thought to be mediated by a direct interaction between these proteins and TATA-binding protein (TBP), TFIIB, or TBP-associated factors, although occasionally cofactors or adapters are required. For ligand-induced activation by the retinoic acid receptor-retinoid X receptor (RAR-RXR) heterodimer, the RAR beta 2 promoter is dependent on the presence of E1A or E1A-like activity, since this promoter is activated by retinoic acid only in cells expressing such proteins. The mechanism underlying this E1A requirement is largely unknown. We now show that direct interaction between RAR and E1A is a requirement for retinoic acid-induced RAR beta 2 activation. The activity of the hormone-dependent activation function 2 (AF-2) of RAR beta is upregulated by E1A, and an interaction between this region and E1A was observed, but not with AF-1 or AF-2 of RXR alpha. This interaction is dependent on conserved region III (CRIII), the 13S mRNA-specific region of E1A. Deletion analysis within this region indicated that the complete CRIII is needed for activation. The putative zinc finger region is crucial, probably as a consequence of interaction with TBP. Furthermore, the region surrounding amino acid 178, partially overlapping with the TBP binding region, is involved in both binding to and activation by AF-2. We propose that E1A functions as a cofactor by interacting with both TBP and RAR, thereby stabilizing the preinitiation complex.

  2. Retinoids induce integrin-independent lymphocyte adhesion through RAR-α nuclear receptor activity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Whelan, Jarrett T.; Wang, Lei; Chen, Jianming

    2014-11-28

    Highlights: • Transcription and translation are required for retinoid-induced lymphocyte adhesion. • RAR activation is sufficient to induced lymphocyte cell adhesion. • Vitamin D derivatives inhibit RAR-prompted lymphocyte adhesion. • Adhesion occurs through a novel binding site within ADAM disintegrin domains. • RARα is a key nuclear receptor for retinoid-dependent lymphocyte cell adhesion. - Abstract: Oxidative metabolites of vitamin A, in particular all-trans-retinoic acid (atRA), have emerged as key factors in immunity by specifying the localization of immune cells to the gut. Although it is appreciated that isomers of retinoic acid activate the retinoic acid receptor (RAR) and retinoid Xmore » receptor (RXR) family of nuclear receptors to elicit cellular changes, the molecular details of retinoic acid action remain poorly defined in immune processes. Here we employ a battery of agonists and antagonists to delineate the specific nuclear receptors utilized by retinoids to evoke lymphocyte cell adhesion to ADAM (adisintegrin and metalloprotease) protein family members. We report that RAR agonism is sufficient to promote immune cell adhesion in both immortal and primary immune cells. Interestingly, adhesion occurs independent of integrin function, and mutant studies demonstrate that atRA-induced adhesion to ADAM members required a distinct binding interface(s) as compared to integrin recognition. Anti-inflammatory corticosteroids as well as 1,25-(OH){sub 2}D{sub 3}, a vitamin D metabolite that prompts immune cell trafficking to the skin, potently inhibited the observed adhesion. Finally, our data establish that induced adhesion was specifically attributable to the RARreceptor isotype. The current study provides novel molecular resolution as to which nuclear receptors transduce retinoid exposure into immune cell adhesion.« less

  3. Design of selective nuclear receptor modulators: RAR and RXR as a case study.

    PubMed

    de Lera, Angel R; Bourguet, William; Altucci, Lucia; Gronemeyer, Hinrich

    2007-10-01

    Retinoic acid receptors (RARs) and retinoid X receptors (RXRs) are members of the nuclear receptor superfamily whose effects on cell growth and survival can be modulated therapeutically by small-molecule ligands. Although compounds that target these receptors are powerful anticancer drugs, their use is limited by toxicity. An improved understanding of the structural biology of RXRs and RARs and recent advances in the chemical synthesis of modified retinoid and rexinoid ligands should enable the rational design of more selective agents that might overcome such problems. Here, we review structural data for RXRs and RARs, discuss strategies in the design of selective RXR and RAR modulators, and consider lessons that can be learned for the design of selective nuclear-receptor modulators in general.

  4. RAR/RXR and PPAR/RXR Signaling in Spinal Cord Injury

    PubMed Central

    van Neerven, Sabien; Mey, Jörg

    2007-01-01

    The retinoid acid receptors (RAR) and peroxisome proliferator-activated receptors (PPAR) have been implicated in the regulation of inflammatory reactions. Both receptor families contain ligand-activated transcription factors which form heterodimers with retinoid X receptors (RXR). We review data that imply RAR/RXR and PPAR/RXR pathways in physiological reactions after spinal cord injury. Experiments show how RAR signaling may improve axonal regeneration and modulate reactions of glia cells. While anti-inflammatory properties of PPAR are well documented in the periphery, their possible roles in the central nervous system have only recently become evident. Due to its anti-inflammatory function this transcription factor family promises to be a useful target after spinal cord or brain lesions. PMID:18060014

  5. Identification of a Novel Non-retinoid Pan Inverse Agonist of the Retinoic Acid Receptors

    PubMed Central

    Busby, Scott A.; Kumar, Naresh; Kuruvilla, Dana S.; Istrate, Monica A.; Conkright, Juliana J.; Wang, Yongjun; Kamenecka, Theodore M.; Cameron, Michael D.; Roush, William R.; Burris, Thomas P.; Griffin, Patrick R.

    2011-01-01

    Retinoids are potent forms of vitamin A and are involved in a broad range of physiological processes and the pharmacological effects of retinoids are primarily mediated by the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). Several natural and synthetic RAR modulators have proven to be clinically useful for a number of therapeutic indications including cancer, psoriasis, and diabetes. Unfortunately, these agents lead to a number of significant side effects. Most synthetic retinoid ligands are based on the retinoid scaffold and thus have similarities to the natural ligand with all previously disclosed RAR ligands having a carboxylic acid that makes a critical ionic bridge within the ligand binding domain of the receptors. The potential therapeutic value offered from RAR modulation provides the impetus to identify novel ligands based on unique scaffolds that may offer improved toxicity and pharmacokinetic profiles. Here we describe the identification of an atypical RAR inverse agonist that represents the first non-acid, non-retinoid direct modulator of RAR receptor subfamily. SR-0065 functions as a pan-RAR inverse agonist suppressing the basal activity of RARα, RARβ, and RARγ as well as inhibiting agonist induced RAR activity. SR-0065 treatment enhanced receptor interaction with a peptide representative of the corepressor SMRT and in cells SR-0065 enhances recruitment of SMRT to RARγ. The acid form of SR-0065, SR-1758, was inactive in all assays. Thus, SR-0065 represents a new class of non-acid, non-retinoid RAR modulator that may be used as a point to initiate development of improved RAR-targeted drugs. PMID:21381756

  6. Characterization of cDNAs encoding the chick retinoic acid receptor gamma 2 and preferential distribution of retinoic acid receptor gamma transcripts during chick skin development.

    PubMed

    Michaille, J J; Blanchet, S; Kanzler, B; Garnier, J M; Dhouailly, D

    1994-12-01

    Retinoic acid receptors alpha, beta and gamma (RAR alpha, beta and gamma) are ligand-inductible transcriptional activators which belong to the steroid/thyroid hormone receptor superfamily. At least two major isoforms (1 and 2) of each RAR arise by differential use of two promoters and alternative splicing. In mouse, the three RAR genes are expressed in stage- and tissue-specific patterns during embryonic development. In order to understand the role of the different RARs in chick, RAR gamma 2 cDNAs were isolated from an 8.5-day (stage 35 of Hamburger and Hamilton) chick embryo skin library. The deduced chick RAR gamma 2 amino acid sequence displays uncommon features such as 21 specific amino acid replacements, 12 of them being clustered in the amino-terminal region (domains A2 and B), and a truncated acidic carboxy-terminal region (F domain). However, the pattern of RAR gamma expression in chick embryo resembles that reported in mouse, particularly in skin where RAR gamma expression occurs in both the dermal and epidermal layers at the beginning of feather formation, and is subsequently restricted to the differentiating epidermal cells. Northern blot analysis suggests that different RAR gamma isoforms could be successively required during chick development.

  7. Radiolabeling and initial biological evaluation of [18F]KBM-1 for imaging RARreceptors in neuroblastoma.

    PubMed

    Solingapuram Sai, Kiran Kumar; Das, Bhaskar C; Sattiraju, Anirudh; Almaguel, Frankis G; Craft, Suzanne; Mintz, Akiva

    2017-03-15

    Retinoic acid receptor alpha (RAR-α) plays a significant role in a number of diseases, including neuroblastoma. Children diagnosed with high-risk neuroblastoma are treated13-cis-retinoic acid, which reduces risk of cancer recurrence. Neuroblastoma cell death is mediated via RAR-α, and expression of RAR-α is upregulated after treatment. A molecular imaging probe that binds RAR-α will help clinicians to diagnose and stratify risk for patients with neuroblastoma, who could benefit from retinoid-based therapy. In this study, we report the radiolabeling, and initial in vivo evaluation of [ 18 F]KBM-1, a novel RAR-α agonist. The radiochemical synthesis of [ 18 F]KBM-1 was carried out through KHF 2 assisted substitution of [ 18 F] - from aryl-substituted pinacolatoesters-based retinoid precursor. In vitro cell uptake assay in human neuroblastoma cell line showed that the uptake of [ 18 F]KBM-1 was significantly inhibited by all three blocking agents (KBM-1, ATRA, BD4) at all the selected incubation times. Standard biodistribution in mice bearing neuroblastoma tumors demonstrated increased tumor uptake from 5min to 60min post radiotracer injection and the uptake ratios for target to non-target (tumor: muscle) increased 2.2-fold to 3.7-fold from 30min to 60min post injection. Tumor uptake in subset of 30min blocking group was 1.7-fold lower than unblocked. These results demonstrate the potential utility of [ 18 F]KBM-1 as a RAR-α imaging agent. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Heterodimers of Retinoic Acid Receptors and Thyroid Hormone Receptors Display Unique Combinatorial Regulatory Properties

    PubMed Central

    Lee, Sangho; Privalsky, Martin L.

    2009-01-01

    Nuclear receptors are ligand-regulated transcription factors that regulate key aspects of metazoan development, differentiation, and homeostasis. Nuclear receptors recognize target genes by binding to specific DNA recognition sequences, denoted hormone response elements (HREs). Many nuclear receptors can recognize HREs as either homodimers or heterodimers. Retinoid X receptors (RXRs), in particular, serve as important heterodimer partners for many other nuclear receptors, including thyroid hormone receptors (TRs), and RXR/TR heterodimers have been proposed to be the primary mediators of target gene regulation by T3 hormone. Here, we report that the retinoic acid receptors (RARs), a distinct class of nuclear receptors, are also efficient heterodimer partners for TRs. These RAR/TR heterodimers form with similar affinities as RXR/TR heterodimers on an assortment of consensus and natural HREs, and preferentially assemble with the RAR partner 5′ of the TR moiety. The corepressor and coactivator recruitment properties of these RAR/TR heterodimers and their transcriptional activities in vivo are distinct from those observed with the corresponding RXR heterodimers. Our studies indicate that RXRs are not unique in their ability to partner with TRs, and that RARs can also serve as robust heterodimer partners and combinatorial regulators of T3-modulated gene expression. PMID:15650024

  9. REACTIVITY PROFILE OF LIGANDS OF MAMMALIAN RETINOIC ACID RECEPTORS: A PRELIMINARY COREPA ANALYSIS

    EPA Science Inventory

    Retinoic acid and associated derivatives comprise a class of endogenous hormones that bind to and activate different families of retinoic acid receptors (RARs, RXRs), and control many aspects of vertebrate development. Identification of potential RAR and RXR ligands is of interes...

  10. Activation of the CRABPII/RAR pathway by curcumin induces retinoic acid mediated apoptosis in retinoic acid resistant breast cancer cells

    PubMed Central

    Thulasiraman, Padmamalini; Garriga, Galen; Danthuluri, Veena; McAndrews, Daniel J.; Mohiuddin, Imran Q.

    2017-01-01

    Due to the anti-proliferative and anti-apoptotic effects of retinoic acid (RA), this hormone has emerged as a target for several diseases, including cancer. However, development of retinoid resistance is a critical issue and efforts to understand the retinoid signaling pathway may identify useful biomarkers for future clinical trials. Apoptotic responses of RA are exhibited through the cellular RA-binding protein II (CRABPII)/retinoic acid receptor (RAR) signaling cascade. Delivery of RA to RAR by CRABPII enhances the transcriptional activity of genes involved in cell death and cell cycle arrest. The purpose of this study was to investigate the role of curcumin in sensitizing RA-resistant triple-negative breast cancer (TNBC) cells to RA-mediated apoptosis. We provide evidence that curcumin upregulates the expression of CRABPII, RARβ and RARγ in two different TNBC cell lines. Co-treatment of the cells with curcumin and RA results in increased apoptosis as demonstrated by elevated cleavage of poly(ADP-ribose) polymerase and cleaved caspase-9. Additionally, silencing CRABPII reverses curcumin sensitization of TNBC cells to the apoptotic inducing effects of RA. These findings provide mechanistic insights into sensitizing TNBC cells to RA-mediated cell death by curcumin-induced upregulation of the CRABPII/RAR pathway. PMID:28350049

  11. Transcriptional regulation of human retinoic acid receptor-alpha (RAR-{alpha}) by Wilms` tumour gene product

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Goodyer, P.R.; Torban, E.; Dehbi, M.

    1994-09-01

    The Wilms` tumor gene encodes a 47-49 kDa transcription factor expressed in kidney, gonads and mesothelium during embryogenesis. Inherited mutations of WT1 lead to aberrant urogenital development and Wilms` tumor, but the role of WT1 in development is not fully understood. Since the human RAR-{alpha} gene contains a potential WT1 binding site at its 5{prime} end, we studied the effect of WT1 co-transfection on expression of an RAR-{alpha} promoter/CAT reporter construct in COS cells. COS cells were plated at 5X10{sup 5} cells/dish in DMEM with 10% FBS and transfected by the Ca/PO4 method with an expression plasmid containing the full-lengthmore » WT1 (-/-) cDNA under the control of the CMV promoter, plasmid containing the RAR-{alpha} promoter (-519 to +36)/CAT reporter and TK/growth hormone plasmid to control for efficiency of transfection. CAT/GH activity at 48 hours was inhibited by co-transfection with increasing amounts of WT1 (-/-); maximum inhibition = 5% of control. WT1 co-transfection did not affect expression of TKGH, nor of a CMV-CAT vector. Expression of WT1 protein in tranfected COS cells was demonstrated by Western blotting. Minimal inhibiton of RAR-{alpha}/CAT activity was seen when cells were co-transfected with vectors containing WT1 deletion mutants, alternate WT1 splicing variants, or WT1 (-/-) cDNA bearing a mutation identified in a patient with Drash syndrome. Gel shift assays indicated binding of WT1 to RAR-{alpha} cDNA but not to an RAR-{alpha} deletion mutant lacking the GCGGGGGGCG site. These observations suggest that WT1 may function to regulate RAR-{alpha} expression during normal development.« less

  12. Cell-type-specific regulation of the retinoic acid receptor mediated by the orphan nuclear receptor TLX.

    PubMed

    Kobayashi, M; Yu, R T; Yasuda, K; Umesono, K

    2000-12-01

    Malformations in the eye can be caused by either an excess or deficiency of retinoids. An early target gene of the retinoid metabolite, retinoic acid (RA), is that encoding one of its own receptors, the retinoic acid receptor beta (RARbeta). To better understand the mechanisms underlying this autologous regulation, we characterized the chick RARbeta2 promoter. The region surrounding the transcription start site of the avian RARbeta2 promoter is over 90% conserved with the corresponding region in mammals and confers strong RA-dependent transactivation in primary cultured embryonic retina cells. This response is selective for RAR but not retinoid X receptor-specific agonists, demonstrating a principal role for RAR(s) in retina cells. Retina cells exhibit a far higher sensitivity to RA than do fibroblasts or osteoblasts, a property we found likely due to expression of the orphan nuclear receptor TLX. Ectopic expression of TLX in fibroblasts resulted in increased sensitivity to RA induction, an effect that is conserved between chick and mammals. We have identified a cis element, the silencing element relieved by TLX (SET), within the RARbeta2 promoter region which confers TLX- and RA-dependent transactivation. These results indicate an important role for TLX in autologous regulation of the RARbeta gene in the eye.

  13. Cell-Type-Specific Regulation of the Retinoic Acid Receptor Mediated by the Orphan Nuclear Receptor TLX†

    PubMed Central

    Kobayashi, Mime; Yu, Ruth T.; Yasuda, Kunio; Umesono, Kazuhiko

    2000-01-01

    Malformations in the eye can be caused by either an excess or deficiency of retinoids. An early target gene of the retinoid metabolite, retinoic acid (RA), is that encoding one of its own receptors, the retinoic acid receptor β (RARβ). To better understand the mechanisms underlying this autologous regulation, we characterized the chick RARβ2 promoter. The region surrounding the transcription start site of the avian RARβ2 promoter is over 90% conserved with the corresponding region in mammals and confers strong RA-dependent transactivation in primary cultured embryonic retina cells. This response is selective for RAR but not retinoid X receptor-specific agonists, demonstrating a principal role for RAR(s) in retina cells. Retina cells exhibit a far higher sensitivity to RA than do fibroblasts or osteoblasts, a property we found likely due to expression of the orphan nuclear receptor TLX. Ectopic expression of TLX in fibroblasts resulted in increased sensitivity to RA induction, an effect that is conserved between chick and mammals. We have identified a cis element, the silencing element relieved by TLX (SET), within the RARβ2 promoter region which confers TLX- and RA-dependent transactivation. These results indicate an important role for TLX in autologous regulation of the RARβ gene in the eye. PMID:11073974

  14. De-repression of RaRF-mediated RAR repression by adenovirus E1A in the nucleolus.

    PubMed

    Um, Soo-Jong; Youn, Hye Sook; Kim, Eun-Joo

    2014-02-21

    Transcriptional activity of the retinoic acid receptor (RAR) is regulated by diverse binding partners, including classical corepressors and coactivators, in response to its ligand retinoic acid (RA). Recently, we identified a novel corepressor of RAR called the retinoic acid resistance factor (RaRF) (manuscript submitted). Here, we report how adenovirus E1A stimulates RAR activity by associating with RaRF. Based on immunoprecipitation (IP) assays, E1A interacts with RaRF through the conserved region 2 (CR2), which is also responsible for pRb binding. The first coiled-coil domain of RaRF was sufficient for this interaction. An in vitro glutathione-S-transferase (GST) pull-down assay was used to confirm the direct interaction between E1A and RaRF. Further fluorescence microscopy indicated that E1A and RaRF were located in the nucleoplasm and nucleolus, respectively. However, RaRF overexpression promoted nucleolar translocation of E1A from the nucleoplasm. Both the RA-dependent interaction of RAR with RaRF and RAR translocation to the nucleolus were disrupted by E1A. RaRF-mediated RAR repression was impaired by wild-type E1A, but not by the RaRF binding-defective E1A mutant. Taken together, our data suggest that E1A is sequestered to the nucleolus by RaRF through a specific interaction, thereby leaving RAR in the nucleoplasm for transcriptional activation. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Docking simulations suggest that all-trans retinoic acid could bind to retinoid X receptors.

    PubMed

    Tsuji, Motonori; Shudo, Koichi; Kagechika, Hiroyuki

    2015-10-01

    Retinoid X receptors (RXRs) are ligand-controlled transcription factors which heterodimerize with other nuclear receptors to regulate gene transcriptions associated with crucial biological events. 9-cis retinoic acid (9cRA), which transactivates RXRs, is believed to be an endogenous RXR ligand. All-trans retinoic acid (ATRA) is a natural ligand for retinoic acid receptors (RARs), which heterodimerize with RXRs. Although the concentration of 9cRA in tissues is very low, ATRA is relatively abundant and some reports show that ATRA activates RXRs. We computationally studied the possibility of ATRA binding to RXRs using two different docking methods with our developed programs to assess the binding affinities of naturally occurring retinoids. The simulations showed good correlations to the reported binding affinities of these molecules for RXRs and RARs.

  16. Human skin levels of retinoic acid and cytochrome P-450-derived 4-hydroxyretinoic acid after topical application of retinoic acid in vivo compared to concentrations required to stimulate retinoic acid receptor-mediated transcription in vitro.

    PubMed Central

    Duell, E A; Aström, A; Griffiths, C E; Chambon, P; Voorhees, J J

    1992-01-01

    Metabolism of retinoic acid to a less active metabolite, 4-hydroxyretinoic acid, occurs via cytochrome P-450 isozyme(s). Effect of a pharmacological dose of retinoic acid on the level of retinoic acid in skin and on cytochrome P-450 activity was investigated. A cream containing 0.1% retinoic acid or cream alone was applied topically to adult human skin for four days under occlusion. Treated areas were removed by a keratome and a microsomal fraction was isolated from each biopsy. In vitro incubation of 3H-retinoic acid with microsomes from in vivo retinoic acid treated sites resulted in a 4.5-fold increase (P = 0.0001, n = 13) in its transformation to 4-hydroxyretinoic acid in comparison to in vitro incubations with microsomes from in vivo cream alone treated sites. This cytochrome P-450 mediated activity was oxygen- and NADPH-dependent and was inhibited 68% by 5 microM ketoconazole (P = 0.0035, n = 8) and 51% by carbon monoxide (P = 0.02, n = 6). Cotransfection of individual retinoic acid receptors (RARs) or retinoid X receptor-alpha (RXR-alpha) and a chloramphenicol acetyl transferase (CAT) reporter plasmid containing a retinoic acid responsive element into CV-1 cells was used to determine the ED50 values for stimulation of CAT activity by retinoic acid and its metabolites. Levels of all trans and 13-cis RA in RA-treated tissues were greater than the ED50 values determined for all three RARs with these compounds. Furthermore, the level of all trans RA was greater than the ED50 for RXR-alpha whereas the 4-OH RA level was greater than the ED50 for RAR-beta and RAR-gamma but less than for RAR-alpha and RXR-alpha. These data suggest that there are sufficient amounts of retinoic acid in treated skin to activate gene transcription over both RARs and RXR-alpha. PMID:1328295

  17. GSK3 is a regulator of RAR-mediated differentiation

    PubMed Central

    Gupta, K; Gulen, F; Sun, L; Aguilera, R; Chakrabarti, A; Kiselar, J; Agarwal, MK; Wald, DN

    2015-01-01

    Acute myeloid leukemia (AML) is the most common form of leukemia in adults. Unfortunately, the standard therapeutic agents used for this disease have high toxicities and poor efficacy. The one exception to these poor outcomes is the use of the retinoid, all-trans retinoic acid (ATRA), for a rare subtype of AML (APL). The use of the differentiation agent, ATRA, in combination with low-dose chemotherapy leads to the long-term survival and presumed cure of 75–85% of patients. Unfortunately ATRA has not been clinically useful for other subtypes of AML. Though many non-APL leukemic cells respond to ATRA, they require significantly higher concentrations of ATRA for effective differentiation. Here we show that the combination of ATRA with glycogen synthase kinase 3 (GSK3) inhibition significantly enhances ATRA-mediated AML differentiation and growth inhibition. These studies have revealed that ATRA's receptor, the retinoic acid receptor (RAR), is a novel target of GSK3 phosphorylation and that GSK3 can impact the expression and transcriptional activity of the RAR. Overall, our studies suggest the clinical potential of ATRA and GSK3 inhibition for AML and provide a mechanistic framework to explain the promising activity of this combination regimen. PMID:22222598

  18. Running increases neurogenesis without retinoic acid receptor activation in the adult mouse dentate gyrus.

    PubMed

    Aberg, Elin; Perlmann, Thomas; Olson, Lars; Brené, Stefan

    2008-01-01

    Both vitamin A deficiency and high doses of retinoids can result in learning and memory impairments, depression as well as decreases in cell proliferation, neurogenesis and cell survival. Physical activity enhances hippocampal neurogenesis and can also exert an antidepressant effect. Here we elucidate a putative link between running, retinoid signaling, and neurogenesis in hippocampus. Adult transgenic reporter mice designed to detect ligand-activated retinoic acid receptors (RAR) or retinoid X receptors (RXR) were used to localize the distribution of activated RAR or RXR at the single-cell level in the brain. Two months of voluntary wheel-running induced an increase in hippocampal neurogenesis as indicated by an almost two-fold increase in doublecortin-immunoreactive cells. Running activity was correlated with neurogenesis. Under basal conditions a distinct pattern of RAR-activated cells was detected in the granule cell layer of the dentate gyrus (DG), thalamus, and cerebral cortex layers 3-4 and to a lesser extent in hippocampal pyramidal cell layers CA1-CA3. Running did not change the number of RAR-activated cells in the DG. There was no correlation between running and RAR activation or between RAR activation and neurogenesis in the DG of hippocampus. Only a few scattered activated retinoid X receptors were found in the DG under basal conditions and after wheel-running, but RXR was detected in other areas such as in the hilus region of hippocampus and in layer VI of cortex cerebri. RAR agonists affect mood in humans and reduce neurogenesis, learning and memory in animal models. In our study, long-term running increased neurogenesis but did not alter RAR ligand activation in the DG in individually housed mice. Thus, our data suggest that the effects of exercise on neurogenesis and other plasticity changes in the hippocampal formation are mediated by mechanisms that do not involve retinoid receptor activation. (c) 2008 Wiley-Liss, Inc.

  19. Both retinoic-acid-receptor- and retinoid-X-receptor-dependent signalling pathways mediate the induction of the brown-adipose-tissue-uncoupling-protein-1 gene by retinoids.

    PubMed Central

    Alvarez, R; Checa, M; Brun, S; Viñas, O; Mampel, T; Iglesias, R; Giralt, M; Villarroya, F

    2000-01-01

    The intracellular pathways and receptors mediating the effects of retinoic acid (RA) on the brown-fat-uncoupling-protein-1 gene (ucp-1) have been analysed. RA activates transcription of ucp-1 and the RA receptor (RAR) is known to be involved in this effect. However, co-transfection of an expression vector for retinoid-X receptor (RXR) increases the action of 9-cis RA but not the effects of all-trans RA on the ucp-1 promoter in brown adipocytes. Either RAR-specific ¿p-[(E)-2-(5,6,7,8,-tetrahydro-5,5,8, 8-tetramethyl-2-naphthalenyl)-1-propenyl]benzoic acid¿ or RXR-specific [isopropyl-(E,E)-(R,S)-11-methoxy-3,7, 11-trimethyldodeca-2,4-dienoate, or methoprene] synthetic compounds increase the expression of UCP-1 mRNA and the activity of chloramphenicol acetyltransferase expression vectors driven by the ucp-1 promoter. The RXR-mediated action of 9-cis RA requires the upstream enhancer region at -2469/-2318 in ucp-1. During brown-adipocyte differentiation RXRalpha and RXRgamma mRNA expression is induced in parallel with UCP-1 mRNA, whereas the mRNA for the three RAR subtypes, alpha, beta and gamma, decreases. Co-transfection of murine expression vectors for the different RAR and RXR subtypes indicates that RARalpha and RARbeta as well as RXRalpha are the major retinoid-receptor subtypes capable of mediating the responsiveness of ucp-1 to retinoids. It is concluded that the effects of retinoids on ucp-1 transcription involve both RAR- and RXR-dependent signalling pathways. The responsiveness of brown adipose tissue to retinoids in vivo relies on a complex combination of the capacity of RAR and RXR subtypes to mediate ucp-1 induction and their distinct expression in the differentiated brown adipocyte. PMID:10600643

  20. ISOLATION AND CHARACTERIZATION OF AXOLOTL NPDC-1 AND ITS EFFECTS ON RETINOIC ACID RECEPTOR SIGNALING

    PubMed Central

    Theodosiou, Maria; Monaghan, James R; Spencer, Michael L; Voss, S Randal; Noonan, Daniel J

    2009-01-01

    Retinoic acid, a key morphogen in early vertebrate development and tissue regeneration, mediates its effects through the binding of receptors that act as ligand-induced transcription factors. These binding events function to recruit an array of transcription co-regulatory proteins to specific gene promoters. One such co-regulatory protein, neuronal proliferation and differentiation control-1 (NPDC-1), is broadly expressed during mammalian development and functions as an in vitro repressor of retinoic acid receptor (RAR)-mediated transcription. To obtain comparative and developmental insights about NPDC-1 function, we cloned the axolotl (Ambystoma mexicanum) orthologue and measured transcript abundances among tissues sampled during the embryonic and juvenile phases of development, and also during spinal cord regeneration. Structurally, the axolotl orthologue of NPDC-1 retained sequence identity to mammalian sequences in all functional domains. Functionally, we observed that axolotl NPDC-1 mRNA expression peaked late in embryogenesis, with highest levels of expression occurring during the time of limb development, a process regulated by retinoic acid signaling. Also similar to what has been observed in mammals, axolotl NPDC-1 directly interacts with axolotl RAR, modulates axolotl RAR DNA binding, and represses cell proliferation and axolotl RAR-mediated gene transcription. These data justify axolotl as a model to further investigate NPDC-1 and its role in regulating retinoic acid signaling. PMID:17331771

  1. Clinical Significance of Retinoic Acid Receptor Beta Promoter Methylation in Prostate Cancer: A Meta-Analysis.

    PubMed

    Dou, MengMeng; Zhou, XueLiang; Fan, ZhiRui; Ding, XianFei; Li, LiFeng; Wang, ShuLing; Xue, Wenhua; Wang, Hui; Suo, Zhenhe; Deng, XiaoMing

    2018-01-01

    Retinoic acid receptor beta (RAR beta) is a retinoic acid receptor gene that has been shown to play key roles during multiple cancer processes, including cell proliferation, apoptosis, migration and invasion. Numerous studies have found that methylation of the RAR beta promoter contributed to the occurrence and development of malignant tumors. However, the connection between RAR beta promoter methylation and prostate cancer (PCa) remains unknown. This meta-analysis evaluated the clinical significance of RAR beta promoter methylation in PCa. We searched all published records relevant to RAR beta and PCa in a series of databases, including PubMed, Embase, Cochrane Library, ISI Web of Science and CNKI. The rates of RAR beta promoter methylation in the PCa and control groups (including benign prostatic hyperplasia and normal prostate tissues) were summarized. In addition, we evaluated the source region of available samples and the methods used to detect methylation. To compare the incidence and variation in RAR beta promoter methylation in PCa and non-PCa tissues, the odds ratio (OR) and 95% confidence interval (CI) were calculated accordingly. All the data were analyzed with the statistical software STATA 12.0. Based on the inclusion and exclusion criteria, 15 articles assessing 1,339 samples were further analyzed. These data showed that the RAR beta promoter methylation rates in PCa tissues were significantly higher than the rates in the non-PCa group (OR=21.65, 95% CI: 9.27-50.57). Subgroup analysis according to the source region of samples showed that heterogeneity in Asia was small (I2=0.0%, P=0.430). Additional subgroup analysis based on the method used to detect RAR beta promoter methylation showed that the heterogeneity detected by MSP (methylation-specific PCR) was relatively small (I2=11.3%, P=0.343). Although studies reported different rates for RAR beta promoter methylation in PCa tissues, the total analysis demonstrated that RAR beta promoter methylation

  2. Identifying the receptor subtype selectivity of retinoid X and retinoic acid receptors via quantum mechanics.

    PubMed

    Tsuji, Motonori; Shudo, Koichi; Kagechika, Hiroyuki

    2017-03-01

    Understanding and identifying the receptor subtype selectivity of a ligand is an important issue in the field of drug discovery. Using a combination of classical molecular mechanics and quantum mechanical calculations, this report assesses the receptor subtype selectivity for the human retinoid X receptor (hRXR) and retinoic acid receptor (hRAR) ligand-binding domains (LBDs) complexed with retinoid ligands. The calculated energies show good correlation with the experimentally reported binding affinities. The technique proposed here is a promising method as it reveals the origin of the receptor subtype selectivity of selective ligands.

  3. Ligand recognition by RAR and RXR receptors: binding and selectivity.

    PubMed

    Sussman, Fredy; de Lera, Angel R

    2005-10-06

    Fundamental biological functions, most notably embriogenesis, cell growth, cell differentiation, and cell apoptosis, are in part regulated by a complex genomic network that starts with the binding (and activation) of retinoids to their cognate receptors, members of the superfamily of nuclear receptors. We have studied ligand recognition of retinoic receptors (RXRalpha and RARgamma) using a molecular-mechanics-based docking method. The protocol used in this work is able to rank the affinity of pairs of ligands for a single retinoid receptor, the highest values corresponding to those that adapt better to the shape of the binding site and generate the optimal set of electrostatic and apolar interactions with the receptor. Moreover, our studies shed light onto some of the energetic contributions to retinoid receptor ligand selectivity. In this regard we show that there is a difference in polarity between the binding site regions that anchor the carboxylate in RAR and RXR, which translates itself into large differences in the energy of interaction of both receptors with the same ligand. We observe that the latter energy change is canceled off by the solvation energy penalty upon binding. This energy compensation is borne out as well by experiments that address the effect of site-directed mutagenesis on ligand binding to RARgamma. The hypothesis that the difference in binding site polarity might be exploited to build RXR-selective ligands is tested with some compounds having a thiazolidinedione anchoring group.

  4. Retinoic acid receptor signalling directly regulates osteoblast and adipocyte differentiation from mesenchymal progenitor cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Green, A.C.; Department of Medicine at St. Vincent's Hospital, The University of Melbourne, Victoria 3065; Kocovski, P.

    Low and high serum retinol levels are associated with increased fracture risk and poor bone health. We recently showed retinoic acid receptors (RARs) are negative regulators of osteoclastogenesis. Here we show RARs are also negative regulators of osteoblast and adipocyte differentiation. The pan-RAR agonist, all-trans retinoic acid (ATRA), directly inhibited differentiation and mineralisation of early osteoprogenitors and impaired the differentiation of more mature osteoblast populations. In contrast, the pan-RAR antagonist, IRX4310, accelerated differentiation of early osteoprogenitors. These effects predominantly occurred via RARγ and were further enhanced by an RARα agonist or antagonist, respectively. RAR agonists similarly impaired adipogenesis in osteogenicmore » cultures. RAR agonist treatment resulted in significant upregulation of the Wnt antagonist, Sfrp4. This accompanied reduced nuclear and cytosolic β-catenin protein and reduced expression of the Wnt target gene Axin2, suggesting impaired Wnt/β-catenin signalling. To determine the effect of RAR inhibition in post-natal mice, IRX4310 was administered to male mice for 10 days and bones were assessed by µCT. No change to trabecular bone volume was observed, however, radial bone growth was impaired. These studies show RARs directly influence osteoblast and adipocyte formation from mesenchymal cells, and inhibition of RAR signalling in vivo impairs radial bone growth in post-natal mice. - Graphical abstract: Schematic shows RAR ligand regulation of osteoblast differentiation in vitro. RARγ antagonists±RARα antagonists promote osteoblast differentiation. RARγ and RARα agonists alone or in combination block osteoblast differentiation, which correlates with upregulation of Sfrp4, and downregulation of nuclear and cytosolic β-catenin and reduced expression of the Wnt target gene Axin2. Red arrows indicate effects of RAR agonists on mediators of Wnt signalling.« less

  5. History of retinoic acid receptors.

    PubMed

    Benbrook, Doris M; Chambon, Pierre; Rochette-Egly, Cécile; Asson-Batres, Mary Ann

    2014-01-01

    The discovery of retinoic acid receptors arose from research into how vitamins are essential for life. Early studies indicated that Vitamin A was metabolized into an active factor, retinoic acid (RA), which regulates RNA and protein expression in cells. Each step forward in our understanding of retinoic acid in human health was accomplished by the development and application of new technologies. Development cDNA cloning techniques and discovery of nuclear receptors for steroid hormones provided the basis for identification of two classes of retinoic acid receptors, RARs and RXRs, each of which has three isoforms, α, β and ɣ. DNA manipulation and crystallographic studies revealed that the receptors contain discrete functional domains responsible for binding to DNA, ligands and cofactors. Ligand binding was shown to induce conformational changes in the receptors that cause release of corepressors and recruitment of coactivators to create functional complexes that are bound to consensus promoter DNA sequences called retinoic acid response elements (RAREs) and that cause opening of chromatin and transcription of adjacent genes. Homologous recombination technology allowed the development of mice lacking expression of retinoic acid receptors, individually or in various combinations, which demonstrated that the receptors exhibit vital, but redundant, functions in fetal development and in vision, reproduction, and other functions required for maintenance of adult life. More recent advancements in sequencing and proteomic technologies reveal the complexity of retinoic acid receptor involvement in cellular function through regulation of gene expression and kinase activity. Future directions will require systems biology approaches to decipher how these integrated networks affect human stem cells, health, and disease.

  6. A Dominant Mutation in Nuclear Receptor Interacting Protein 1 Causes Urinary Tract Malformations via Dysregulation of Retinoic Acid Signaling.

    PubMed

    Vivante, Asaf; Mann, Nina; Yonath, Hagith; Weiss, Anna-Carina; Getwan, Maike; Kaminski, Michael M; Bohnenpoll, Tobias; Teyssier, Catherine; Chen, Jing; Shril, Shirlee; van der Ven, Amelie T; Ityel, Hadas; Schmidt, Johanna Magdalena; Widmeier, Eugen; Bauer, Stuart B; Sanna-Cherchi, Simone; Gharavi, Ali G; Lu, Weining; Magen, Daniella; Shukrun, Rachel; Lifton, Richard P; Tasic, Velibor; Stanescu, Horia C; Cavaillès, Vincent; Kleta, Robert; Anikster, Yair; Dekel, Benjamin; Kispert, Andreas; Lienkamp, Soeren S; Hildebrandt, Friedhelm

    2017-08-01

    Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of CKD in the first three decades of life. However, for most patients with CAKUT, the causative mutation remains unknown. We identified a kindred with an autosomal dominant form of CAKUT. By whole-exome sequencing, we identified a heterozygous truncating mutation (c.279delG, p.Trp93fs*) of the nuclear receptor interacting protein 1 gene ( NRIP1 ) in all seven affected members. NRIP1 encodes a nuclear receptor transcriptional cofactor that directly interacts with the retinoic acid receptors (RARs) to modulate retinoic acid transcriptional activity. Unlike wild-type NRIP1, the altered NRIP1 protein did not translocate to the nucleus, did not interact with RAR α , and failed to inhibit retinoic acid-dependent transcriptional activity upon expression in HEK293 cells. Notably, we also showed that treatment with retinoic acid enhanced NRIP1 binding to RAR α RNA in situ hybridization confirmed Nrip1 expression in the developing urogenital system of the mouse. In explant cultures of embryonic kidney rudiments, retinoic acid stimulated Nrip1 expression, whereas a pan-RAR antagonist strongly reduced it. Furthermore, mice heterozygous for a null allele of Nrip1 showed a CAKUT-spectrum phenotype. Finally, expression and knockdown experiments in Xenopus laevis confirmed an evolutionarily conserved role for NRIP1 in renal development. These data indicate that dominant NRIP1 mutations can cause CAKUT by interference with retinoic acid transcriptional signaling, shedding light on the well documented association between abnormal vitamin A levels and renal malformations in humans, and suggest a possible gene-environment pathomechanism in this disease. Copyright © 2017 by the American Society of Nephrology.

  7. Selective Cooperation between Fatty Acid Binding Proteins and Peroxisome Proliferator-Activated Receptors in Regulating Transcription

    PubMed Central

    Tan, Nguan-Soon; Shaw, Natacha S.; Vinckenbosch, Nicolas; Liu, Peng; Yasmin, Rubina; Desvergne, Béatrice; Wahli, Walter; Noy, Noa

    2002-01-01

    Lipophilic compounds such as retinoic acid and long-chain fatty acids regulate gene transcription by activating nuclear receptors such as retinoic acid receptors (RARs) and peroxisome proliferator-activated receptors (PPARs). These compounds also bind in cells to members of the family of intracellular lipid binding proteins, which includes cellular retinoic acid-binding proteins (CRABPs) and fatty acid binding proteins (FABPs). We previously reported that CRABP-II enhances the transcriptional activity of RAR by directly targeting retinoic acid to the receptor. Here, potential functional cooperation between FABPs and PPARs in regulating the transcriptional activities of their common ligands was investigated. We show that adipocyte FABP and keratinocyte FABP (A-FABP and K-FABP, respectively) selectively enhance the activities of PPARγ and PPARβ, respectively, and that these FABPs massively relocate to the nucleus in response to selective ligands for the PPAR isotype which they activate. We show further that A-FABP and K-FABP interact directly with PPARγ and PPARβ and that they do so in a receptor- and ligand-selective manner. Finally, the data demonstrate that the presence of high levels of K-FABP in keratinocytes is essential for PPARβ-mediated induction of differentiation of these cells. Taken together, the data establish that A-FABP and K-FABP govern the transcriptional activities of their ligands by targeting them to cognate PPARs in the nucleus, thereby enabling PPARs to exert their biological functions. PMID:12077340

  8. Receptor-selective retinoids implicate retinoic acid receptor alpha and gamma in the regulation of bmp-2 and bmp-4 in F9 embryonal carcinoma cells.

    PubMed

    Rogers, M B

    1996-01-01

    The effect of retinoids on malignant cells and embryos indicates that retinoids influence the expression of growth factors or alter the response of cells to growth factors. The bone morphogenetic proteins, Bmp-2 and Bmp-4, are candidates for such growth factors because retinoic acid (RA) treatment of F9 embryonal carcinoma cells induced Bmp-2 mRNA, while simultaneously repressing Bmp-4 levels. Also, recombinant Bmp-2 affected the growth and differentiation of these cells. Regulation of each gene was concentration dependent and required continuous RA treatment. The short half-lives of the Bmp-2 (75 +/- 11 min) and Bmp-4 (70 +/- 4 min) mRNAs suggest that their abundance is primarily controlled at the transcriptional level. To determine which RA receptor (RAR) controls bmp-2 and bmp-4 expression, F9 cells were exposed to various receptor-selective retinoids. RAR alpha- and gamma-selective retinoids induced Bmp-2 and repressed Bmp-4 equally as well as all-trans RA. In contrast, a RAR beta-selective retinoid had little effect on Bmp-2 induction but repressed Bmp-4. A RAR alpha-selective antagonist inhibited all-trans RA stimulation of Bmp-2, although not as dramatically as a RAR beta gamma-selective antagonist. No differences were observed between Bmp levels in all-trans RA and 9-cis RA-treated cells, indicating that the RXRs play little part in controlling these genes. The results are consistent with RAR alpha and gamma-controlled Bmp-2 and Bmp-4 regulation.

  9. Arsenic as an endocrine disruptor: arsenic disrupts retinoic acid receptor-and thyroid hormone receptor-mediated gene regulation and thyroid hormone-mediated amphibian tail metamorphosis.

    PubMed

    Davey, Jennifer C; Nomikos, Athena P; Wungjiranirun, Manida; Sherman, Jenna R; Ingram, Liam; Batki, Cavus; Lariviere, Jean P; Hamilton, Joshua W

    2008-02-01

    Chronic exposure to excess arsenic in drinking water has been strongly associated with increased risks of multiple cancers, diabetes, heart disease, and reproductive and developmental problems in humans. We previously demonstrated that As, a potent endocrine disruptor at low, environmentally relevant levels, alters steroid signaling at the level of receptor-mediated gene regulation for all five steroid receptors. The goal of this study was to determine whether As can also disrupt gene regulation via the retinoic acid (RA) receptor (RAR) and/or the thyroid hormone (TH) receptor (TR) and whether these effects are similar to previously observed effects on steroid regulation. Human embryonic NT2 or rat pituitary GH3 cells were treated with 0.01-5 microM sodium arsenite for 24 hr, with or without RA or TH, respectively, to examine effects of As on receptor-mediated gene transcription. At low, noncytotoxic doses, As significantly altered RAR-dependent gene transcription of a transfected RAR response element-luciferase construct and the native RA-inducible cytochrome P450 CYP26A gene in NT2 cells. Likewise, low-dose As significantly altered expression of a transfected TR response element-luciferase construct and the endogenous TR-regulated type I deiodinase (DIO1) gene in a similar manner in GH3 cells. An amphibian ex vivo tail metamorphosis assay was used to examine whether endocrine disruption by low-dose As could have specific pathophysiologic consequences, because tail metamorphosis is tightly controlled by TH through TR. TH-dependent tail shrinkage was inhibited in a dose-dependent manner by 0.1- 4.0 microM As. As had similar effects on RAR- and TR-mediated gene regulation as those previously observed for the steroid receptors, suggesting a common mechanism or action. Arsenic also profoundly affected a TR-dependent developmental process in a model animal system at very low concentrations. Because RAR and TH are critical for both normal human development and adult

  10. REACTIVITY PROFILE OF CONFORMATIONALLY-FLEXIBLE RETINOID RECEPTOR LIGANDS

    EPA Science Inventory

    Retinoids and associated derivatives represent a class of endogenousr hormones that bind to and activate different families of retinoic acid receptors (RARs, RXRs), and control many aspects of normal vertebrate development. Identification of potential RAR and RXRs ligands is of i...

  11. SIGNALLING THROUGH RETINOIC ACID RECEPTORS IN CARDIAC DEVELOPMENT: DOING THE RIGHT THINGS AT THE RIGHT TIMES

    PubMed Central

    Xavier-Neto, José; Costa, Ângela M. Sousa; Figueira, Ana Carolina M.; Caiaffa, Carlo Donato; do Amaral, Fabio Neves; Peres, Lara Maldanis Cerqueira; da Silva, Bárbara Santos Pires; Santos, Luana Nunes; Moise, Alexander R.; Castillo, Hozana Andrade

    2015-01-01

    Retinoic acid (RA) is a terpenoid that is synthesized from Vitamin A/retinol (ROL) and binds to the nuclear receptors retinoic acid receptor (RAR)/retinoid X receptor (RXR) to control multiple developmental processes in vertebrates. The available clinic and experimental data provide uncontested evidence for the pleiotropic roles of RA signalling in development of multiple embryonic structures and organs such eyes, central nervous system, gonads, lungs and heart. The development of any of these above-mentioned embryonic organ systems can be effectively utilized to showcase the many strategies utilized by RA signalling. However, it is very likely that the strategies employed to transfer RA signals during cardiac development comprise the majority of the relevant and sophisticated ways through which retinoid signals can be conveyed in a complex biological system. Here, we provide the reader with arguments indicating that RA signalling is exquisitely regulated according to specific phases of cardiac development and that RA signalling itself is one of the major regulators of the timing of cardiac morphogenesis and differentiation. We will focus on the role of signalling by RA receptors (RARs) in early phases of heart development. PMID:25134739

  12. Molecular characterization and gene expression patterns of retinoid receptors, in normal and regenerating tissues of the sea cucumber, Holothuria glaberrima.

    PubMed

    Viera-Vera, Jorge; García-Arrarás, José E

    2018-05-15

    Retinoic acid receptors (RAR) and retinoid X receptors (RXR) are ligand-mediated transcription factors that synchronize intricate signaling networks in metazoans. Dimer formation between these two nuclear receptors mediates the recruitment of co-regulatory complexes coordinating the progression of signaling cascades during developmental and regenerative events. In the present study we identified and characterized the receptors for retinoic acid in the sea cucumber Holothuria glaberrima; a model system capable of regenerative organogenesis during adulthood. Molecular characterizations revealed the presence of three isoforms of RAR and two of RXR as a consequence of alternative splicing events. Various analyses including: primary structure sequencing, phylogenetic analysis, protein domain prediction, and multiple sequence alignment further confirmed their identity. Semiquantitative reverse transcription PCR analysis of each receptor isoform herein identified showed that the retinoid receptors are expressed in all tissues sampled: the mesenteries, respiratory trees, muscles, gonads, and the digestive tract. During regenerative organogenesis two of the receptors (RAR-L and RXR-T) showed differential expression in the posterior segment while RAR-S is differentially expressed in the anterior segment of the intestine. This work presents the first description of the components relaying the signaling for retinoic acid within this model system. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Dominant negative retinoic acid receptor initiates tumor formation in mice.

    PubMed

    Kupumbati, Tara S; Cattoretti, Giorgio; Marzan, Christine; Farias, Eduardo F; Taneja, Reshma; Mira-y-Lopez, Rafael

    2006-03-24

    Retinoic acid suppresses cell growth and promotes cell differentiation, and pharmacological retinoic acid receptor (RAR) activation is anti-tumorigenic. This begs the question of whether chronic physiological RAR activation by endogenous retinoids is likewise anti-tumorigenic. To address this question, we generated transgenic mice in which expression of a ligand binding defective dominant negative RARalpha (RARalphaG303E) was under the control of the mouse mammary tumor virus (MMTV) promoter. The transgene was expressed in the lymphoid compartment and in the mammary epithelium. Observation of aging mice revealed that transgenic mice, unlike their wild type littermates, developed B cell lymphomas at high penetrance, with a median latency of 40 weeks. MMTV-RARalphaG303E lymphomas were high grade Pax-5+, surface H+L Ig negative, CD69+ and BCL6- and cytologically and phenotypically resembled human adult high grade (Burkitt's or lymphoblastic) lymphomas. We postulated that mammary tumors might arise after a long latency period as seen in other transgenic models of breast cancer. We tested this idea by transplanting transgenic epithelium into the cleared fat pads of wild type hosts, thus bypassing lymphomagenesis. At 17 months post-transplantation, a metastatic mammary adenocarcinoma developed in one of four transplanted glands whereas no tumors developed in sixteen of sixteen endogenous glands with wild type epithelium. These findings suggest that physiological RAR activity may normally suppress B lymphocyte and mammary epithelial cell growth and that global RAR inactivation is sufficient to initiate a stochastic process of tumor development requiring multiple transforming events. Our work makes available to the research community a new animal resource that should prove useful as an experimental model of aggressive sporadic lymphoma in immunologically uncompromised hosts. We anticipate that it may also prove useful as a model of breast cancer.

  14. Reduced adiponectin expression after high-fat diet is associated with selective up-regulation of ALDH1A1 and further retinoic acid receptor signaling in adipose tissue

    PubMed Central

    Landrier, Jean-Francois; Kasiri, Elnaz; Karkeni, Esma; Mihály, Johanna; Béke, Gabriella; Weiss, Kathrin; Lucas, Renata; Aydemir, Gamze; Salles, Jérome; Walrand, Stéphane; de Lera, Angel R.; Rühl, Ralph

    2017-01-01

    Adiponectin is an adipocyte-derived adipokine with potent antidiabetic, anti-inflammatory, and antiatherogenic activity. Long-term, high-fat diet results in gain of body weight, adiposity, further inflammatory-based cardiovascular diseases, and reduced adiponectin secretion. Vitamin A derivatives/retinoids are involved in several of these processes, which mainly take place in white adipose tissue (WAT). In this study, we examined adiponectin expression as a function of dietary high-fat and high–vitamin A conditions in mice. A decrease of adiponectin expression in addition to an up-regulation of aldehyde dehydrogenase A1 (ALDH1A1), retinoid signaling, and retinoic acid response element signaling was selectively observed in WAT of mice fed a normal–vitamin A, high-fat diet. Reduced adiponectin expression in WAT was also observed in mice fed a high–vitamin A diet. Adipocyte cell culture revealed that endogenous and synthetic retinoic acid receptor (RAR)α- and RARγ-selective agonists, as well as a synthetic retinoid X receptor agonist, efficiently reduced adiponectin expression, whereas ALDH1A1 expression only increased with RAR agonists. We conclude that reduced adiponectin expression under high-fat dietary conditions is dependent on 1) increased ALDH1A1 expression in adipocytes, which does not increase all-trans-retinoic acid levels; 2) further RAR ligand–induced, WAT-selective, increased retinoic acid response element–mediated signaling; and 3) RAR ligand–dependent reduction of adiponectin expression.—Landrier, J.-F., Kasiri, E., Karkeni, E., Mihály, J., Béke, G., Weiss, K., Lucas, R., Aydemir, G., Salles, J., Walrand, S., de Lera, A. R., Rühl, R. Reduced adiponectin expression after high-fat diet is associated with selective up-regulation of ALDH1A1 and further retinoic acid receptor signaling in adipose tissue. PMID:27729412

  15. Urinary retinoic acid receptor-β2 gene promoter methylation and hyaluronidase activity as noninvasive tests for diagnosis of bladder cancer.

    PubMed

    Eissa, Sanaa; Zohny, Samir F; Shehata, Hanan Hussien; Hegazy, Marwa G A; Salem, Ahmed M; Esmat, Mohamed

    2012-04-01

    We evaluated the significance of urinary retinoic acid receptor-β2 (RAR-β2) gene promoter methylation and hyaluronidase activity in comparison with voided urine cytology (VUC) in diagnosis of bladder cancer. This study included 100 patients diagnosed with bladder cancer, 65 patients with benign urological disorders and 51 healthy volunteers. Urine supernatant was used for determining hyaluronidase activity by zymography while urine sediment was used for cytology and detection of methylated RAR-β2 gene promoter by methylation specific nested PCR. The sensitivity and specificity were 53% and 90.5% for VUC, 65% and 89.7% for percent methylation fraction of RAR-β2 gene promoter, and 89% and 90.5% for hyaluronidase activity; combination of the three parameters increased sensitivity to 95%. A significant association was observed between investigated markers and advanced grade tumor. Combined use of RAR-β2 gene promoter methylation, hyaluronidase activity and VUC is promising non-invasive tool for bladder cancer detection. Copyright © 2012. Published by Elsevier Inc.

  16. Dysregulation of retinoic acid receptor diminishes hepatocyte permissiveness to hepatitis B virus infection through modulation of sodium taurocholate cotransporting polypeptide (NTCP) expression.

    PubMed

    Tsukuda, Senko; Watashi, Koichi; Iwamoto, Masashi; Suzuki, Ryosuke; Aizaki, Hideki; Okada, Maiko; Sugiyama, Masaya; Kojima, Soichi; Tanaka, Yasuhito; Mizokami, Masashi; Li, Jisu; Tong, Shuping; Wakita, Takaji

    2015-02-27

    Sodium taurocholate cotransporting polypeptide (NTCP) is an entry receptor for hepatitis B virus (HBV) and is regarded as one of the determinants that confer HBV permissiveness to host cells. However, how host factors regulate the ability of NTCP to support HBV infection is largely unknown. We aimed to identify the host signaling that regulated NTCP expression and thereby permissiveness to HBV. Here, a cell-based chemical screening method identified that Ro41-5253 decreased host susceptibility to HBV infection. Pretreatment with Ro41-5253 inhibited the viral entry process without affecting HBV replication. Intriguingly, Ro41-5253 reduced expression of both NTCP mRNA and protein. We found that retinoic acid receptor (RAR) regulated the promoter activity of the human NTCP (hNTCP) gene and that Ro41-5253 repressed the hNTCP promoter by antagonizing RAR. RAR recruited to the hNTCP promoter region, and nucleotides -112 to -96 of the hNTCP was suggested to be critical for RAR-mediated transcriptional activation. HBV susceptibility was decreased in pharmacologically RAR-inactivated cells. CD2665 showed a stronger anti-HBV potential and disrupted the spread of HBV infection that was achieved by continuous reproduction of the whole HBV life cycle. In addition, this mechanism was significant for drug development, as antagonization of RAR blocked infection of multiple HBV genotypes and also a clinically relevant HBV mutant that was resistant to nucleoside analogs. Thus, RAR is crucial for regulating NTCP expression that determines permissiveness to HBV infection. This is the first demonstration showing host regulation of NTCP to support HBV infection. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  17. Dysregulation of Retinoic Acid Receptor Diminishes Hepatocyte Permissiveness to Hepatitis B Virus Infection through Modulation of Sodium Taurocholate Cotransporting Polypeptide (NTCP) Expression*

    PubMed Central

    Tsukuda, Senko; Watashi, Koichi; Iwamoto, Masashi; Suzuki, Ryosuke; Aizaki, Hideki; Okada, Maiko; Sugiyama, Masaya; Kojima, Soichi; Tanaka, Yasuhito; Mizokami, Masashi; Li, Jisu; Tong, Shuping; Wakita, Takaji

    2015-01-01

    Sodium taurocholate cotransporting polypeptide (NTCP) is an entry receptor for hepatitis B virus (HBV) and is regarded as one of the determinants that confer HBV permissiveness to host cells. However, how host factors regulate the ability of NTCP to support HBV infection is largely unknown. We aimed to identify the host signaling that regulated NTCP expression and thereby permissiveness to HBV. Here, a cell-based chemical screening method identified that Ro41-5253 decreased host susceptibility to HBV infection. Pretreatment with Ro41-5253 inhibited the viral entry process without affecting HBV replication. Intriguingly, Ro41-5253 reduced expression of both NTCP mRNA and protein. We found that retinoic acid receptor (RAR) regulated the promoter activity of the human NTCP (hNTCP) gene and that Ro41-5253 repressed the hNTCP promoter by antagonizing RAR. RAR recruited to the hNTCP promoter region, and nucleotides −112 to −96 of the hNTCP was suggested to be critical for RAR-mediated transcriptional activation. HBV susceptibility was decreased in pharmacologically RAR-inactivated cells. CD2665 showed a stronger anti-HBV potential and disrupted the spread of HBV infection that was achieved by continuous reproduction of the whole HBV life cycle. In addition, this mechanism was significant for drug development, as antagonization of RAR blocked infection of multiple HBV genotypes and also a clinically relevant HBV mutant that was resistant to nucleoside analogs. Thus, RAR is crucial for regulating NTCP expression that determines permissiveness to HBV infection. This is the first demonstration showing host regulation of NTCP to support HBV infection. PMID:25550158

  18. Reduced RAR-β gene expression in Benzo(a)Pyrene induced lung cancer mice is upregulated by DOTAP lipo-ATRA treatment.

    PubMed

    Viswanathan, S; Berlin Grace, V M

    2018-08-20

    Molecular targeted therapy for specific genes is an emerging research. Retinoic Acid Receptor (RAR-β) is a key tumor suppressor which is found to be lost drastically during much cancer progression. We hence, analyzed the expression level of RAR-β gene during B(a)P induced lung cancer development in mice and studied the lung cancer targeted action of All Trans Retinoic Acid (ATRA) in DOTAP liposomal formulation. The effect of its treatment on lung cancer was determined by histopathological analysis. RAR-β gene expression was assessed by RT-PCR and qPCR. A distinct band for RAR-β gene (density - 0.5123 for lung and 0.5160 for liver) was observed in normal mice, whereas no visible band was observed in cancer induced group, indicating loss of RAR-β gene expression. Both ATRA and lipo-ATRA treated groups showed detectable RAR-β expression with relatively lesser density than the normal group. The expression was more intense in lipo-ATRA treatment (density-0.2973) compared with free ATRA treatment (density-0.1549) in lung tissues. The qPCR results also have highlighted a highly significant (p ≤ 0.01) variation RQ values between lipo-ATRA group (15.46 ± 1.54) and free ATRA group (7.58 ± 1.30) in lung tissue sample on 30th day. The mean RQ value for normal lung on 30th day was 20.86 ± 2.58 against the cancer control. The 120th day mice also showed the similar RAR-β expression pattern with further declined expression levels as there was no treatment given after 30 days. Interestingly, the lipo-ATRA treatment could show a highly significant (p ≤ 0.001) expression (12.00 ± 2.31) when compared with free ATRA treatment (3.31 ± 0.58) which implies that the lipo-ATRA formulation could result in sustained delivery of ATRA in target site. Histopathology of lung and liver on 120th day also revealed an effective therapeutic indication in lipo-ATRA treatment compared to free ATRA treatment due to lipo-ATRA's stealth property and it

  19. Utilization of DR1 as true RARE in regulating the Ssm, a novel retinoic acid-target gene in the mouse testis.

    PubMed

    Han, Kyuyong; Song, Haengseok; Moon, Irene; Augustin, Robert; Moley, Kelle; Rogers, Melissa; Lim, Hyunjung

    2007-03-01

    Various nuclear receptors form dimers to activate target genes via specific response elements located within promoters or enhancers. Retinoid X receptor (RXR) serves as a dimerization partner for many nuclear receptors including retinoic acid receptor (RAR) and peroxisome proliferator-activated receptor (PPAR). Dimers show differential preference towards directly repeated response elements with 1-5 nucleotide spacing, and direct repeat 1 (DR1) is a promiscuous element which recruits RAR/RXR, RXR/RXR, and PPAR/RXR in vitro. In the present investigation, we report identification of a novel RAR/RXR target gene which is regulated by DR1s in the promoter region. This gene, namely spermatocyte-specific marker (Ssm), recruits all the three combinations of nuclear receptors in vitro, but in vivo regulation is observed by trans-retinoic acid-activated RAR/RXR dimer. Indeed, chromatin immunoprecipitation experiment demonstrates binding of RARbeta and RXRalpha in the promoter region of the Ssm. Interestingly, expression of Ssm is almost exclusively observed in spermatocytes in the adult mouse testis, where RA signaling is known to regulate developmental program of male germ cells. The results show that Ssm is a RAR/RXR target gene uniquely using DR1 and exhibits stage-specific expression in the mouse testis with potential function in later stages of spermatogenesis. This finding exemplifies usage of DR1s as retinoic acid response element (RARE) under a specific in vivo context.

  20. Combinational treatment with retinoic acid derivatives in non-small cell lung carcinoma in vitro.

    PubMed

    Choi, Eun Jung; Whang, Young Mi; Kim, Seok Jin; Kim, Hyun Jin; Kim, Yeul Hong

    2007-09-01

    The growth inhibitory effects of four retinoic acid (RA) derivatives, 9-cis RA, 13-cis RA, N-(4-hydroxyphenyl) retinamide (4-HPR), and all-trans retinoic acid (ATRA) were compared. In addition, the effects of various combinations of these four agents were examined on non-small cell lung carcinoma (NSCLC) cell-lines, and on the expressions of retinoic acid receptors (RARs) and retinoid X receptors (RXRs) on these cells. At the clinically achievable concentration of 1 microM, only 4-HPR inhibited the growths of H1299 and H460 cells-lines. However, retinoic acid receptor beta(RAR beta) expression was up-regulated on H460 and H1299 cells treated with 1 microM of ATRA, 13-cis RA, or 9-cis RA. All NSCLC cell lines showed growth inhibition when exposed sequentially to 1 microM ATRA and 0.1 microM 4-HPR. In particular, sequential treatment with 1 microM ATRA or 13-cis RA and 4-HPR markedly inhibited H1703 cell growth; these cells exhibited no basal RAR beta expression and were refractory to 4-HPR. However, in NSCLC cell lines that expressed RAR beta, the expressional levels of RAR beta were up-regulated by ATRA alone and by sequential treatment with ATRA and 4-HPR. 4-HPR was found to be the most active of the four agents in terms of NSCLC growth-inhibition. Moreover, sequential treatments with ATRA or 13-cis RA followed by 4-HPR were found to have synergistic growth-inhibitory effects and to regulate RAR expression.

  1. PREDICTING RETINOID RECEPTOR BINDING AFFINITY: COREPA-M APPLICATION

    EPA Science Inventory

    Retinoic acid and associated vitamin A derivatives comprise a class of endogenous hormones that activate different retinoic acid receptors RARs). Transcriptional events subsequent to this activation are key to controlling several aspects of vertebrate development. As such, identi...

  2. Cardiac compartment-specific overexpression of a modified retinoic acid receptor produces dilated cardiomyopathy and congestive heart failure in transgenic mice.

    PubMed

    Colbert, M C; Hall, D G; Kimball, T R; Witt, S A; Lorenz, J N; Kirby, M L; Hewett, T E; Klevitsky, R; Robbins, J

    1997-10-15

    Retinoids play a critical role in cardiac morphogenesis. To examine the effects of excessive retinoid signaling on myocardial development, transgenic mice that overexpress a constitutively active retinoic acid receptor (RAR) controlled by either the alpha- or beta-myosin heavy chain (MyHC) promoter were generated. Animals carrying the alpha-MyHC-RAR transgene expressed RARs in embryonic atria and in adult atria and ventricles, but developed no signs of either malformations or disease. In contrast, beta-MyHC-RAR animals, where expression was activated in fetal ventricles, developed a dilated cardiomyopathy that varied in severity with transgene copy number. Characteristic postmortem lesions included biventricular chamber dilation and left atrial thrombosis; the incidence and severity of these lesions increased with increasing copy number. Transcript analyses showed that molecular markers of hypertrophy, alpha-skeletal actin, atrial natriuretic factor and beta-MyHC, were upregulated. Cardiac performance of transgenic hearts was evaluated using the isolated perfused working heart model as well as in vivo, by transthoracic M-mode echocardiography. Both analyses showed moderate to severe impairment of left ventricular function and reduced cardiac contractility. Thus, expression of a constitutively active RAR in developing atria and/ or in postnatal ventricles is relatively benign, while ventricular expression during gestation can lead to significant cardiac dysfunction.

  3. Cardiac compartment-specific overexpression of a modified retinoic acid receptor produces dilated cardiomyopathy and congestive heart failure in transgenic mice.

    PubMed Central

    Colbert, M C; Hall, D G; Kimball, T R; Witt, S A; Lorenz, J N; Kirby, M L; Hewett, T E; Klevitsky, R; Robbins, J

    1997-01-01

    Retinoids play a critical role in cardiac morphogenesis. To examine the effects of excessive retinoid signaling on myocardial development, transgenic mice that overexpress a constitutively active retinoic acid receptor (RAR) controlled by either the alpha- or beta-myosin heavy chain (MyHC) promoter were generated. Animals carrying the alpha-MyHC-RAR transgene expressed RARs in embryonic atria and in adult atria and ventricles, but developed no signs of either malformations or disease. In contrast, beta-MyHC-RAR animals, where expression was activated in fetal ventricles, developed a dilated cardiomyopathy that varied in severity with transgene copy number. Characteristic postmortem lesions included biventricular chamber dilation and left atrial thrombosis; the incidence and severity of these lesions increased with increasing copy number. Transcript analyses showed that molecular markers of hypertrophy, alpha-skeletal actin, atrial natriuretic factor and beta-MyHC, were upregulated. Cardiac performance of transgenic hearts was evaluated using the isolated perfused working heart model as well as in vivo, by transthoracic M-mode echocardiography. Both analyses showed moderate to severe impairment of left ventricular function and reduced cardiac contractility. Thus, expression of a constitutively active RAR in developing atria and/ or in postnatal ventricles is relatively benign, while ventricular expression during gestation can lead to significant cardiac dysfunction. PMID:9329959

  4. Retinoic acid has different effects on UCP1 expression in mouse and human adipocytes

    PubMed Central

    2013-01-01

    Background Increased adipose thermogenesis is being considered as a strategy aimed at preventing or reversing obesity. Thus, regulation of the uncoupling protein 1 (UCP1) gene in human adipocytes is of significant interest. Retinoic acid (RA), the carboxylic acid form of vitamin A, displays agonist activity toward several nuclear hormone receptors, including RA receptors (RARs) and peroxisome proliferator-activated receptor δ (PPARδ). Moreover, RA is a potent positive regulator of UCP1 expression in mouse adipocytes. Results The effects of all-trans RA (ATRA) on UCP1 gene expression in models of mouse and human adipocyte differentiation were investigated. ATRA induced UCP1 expression in all mouse white and brown adipocytes, but inhibited or had no effect on UCP1 expression in human adipocyte cell lines and primary human white adipocytes. Experiments with various RAR agonists and a RAR antagonist in mouse cells demonstrated that the stimulatory effect of ATRA on UCP1 gene expression was indeed mediated by RARs. Consistently, a PPARδ agonist was without effect. Moreover, the ATRA-mediated induction of UCP1 expression in mouse adipocytes was independent of PPARγ coactivator-1α. Conclusions UCP1 expression is differently affected by ATRA in mouse and human adipocytes. ATRA induces UCP1 expression in mouse adipocytes through activation of RARs, whereas expression of UCP1 in human adipocytes is not increased by exposure to ATRA. PMID:24059847

  5. Induction of intermediate mesoderm by retinoic acid receptor signaling from differentiating mouse embryonic stem cells.

    PubMed

    Oeda, Shiho; Hayashi, Yohei; Chan, Techuan; Takasato, Minoru; Aihara, Yuko; Okabayashi, Koji; Ohnuma, Kiyoshi; Asashima, Makoto

    2013-01-01

    Renal lineages including kidney are derived from intermediate mesoderm, which are differentiated from a subset of caudal undifferentiated mesoderm. The inductive mechanisms of mammalian intermediate mesoderm and renal lineages are still poorly understood. Mouse embryonic stem cells (mESCs) can be a good in vitro model to reconstitute the developmental pathway of renal lineages and to analyze the mechanisms of the sequential differentiation. We examined the effects of Activin A and retinoic acid (RA) on the induction of intermediate mesoderm from mESCs under defined, serum-free, adherent, monolayer culture conditions. We measured the expression level of intermediate mesodermal marker genes and examined the developmental potential of the differentiated cells into kidney using an ex vivo transplantation assay. Adding Activin A followed by RA to mESC cultures induced the expression of marker genes and proteins for intermediate mesoderm, odd-skipped related 1 (Osr1) and Wilm’s Tumor 1 (Wt1). These differentiated cells integrated into laminin-positive tubular cells and Pax2-positive renal cells in cultured embryonic kidney explants. We demonstrated that intermediate mesodermal marker expression was also induced by RA receptor (RAR) agonist, but not by retinoid X receptor (RXR) agonists. Furthermore, the expression of these markers was decreased by RAR antagonists. We directed the differentiation of mESCs into intermediate mesoderm using Activin A and RA and revealed the role of RAR signaling in this differentiation. These methods and findings will improve our understanding of renal lineage development and could contribute to the regenerative medicine of kidney.

  6. Age-related change in the retinoid X receptor beta gene expression in peripheral blood mononuclear cells of healthy volunteers: effect of 13-cis retinoic acid supplementation.

    PubMed

    Brtko, J; Rock, E; Nezbedova, P; Krizanova, O; Dvorcakova, M; Minet-Quinard, R; Farges, M-C; Ribalta, J; Winklhofer-Roob, B M; Vasson, M-P; Macejova, D

    2007-01-01

    The regulation of cell growth and differentiation and also expression of a number of genes by retinoids are mediated by nuclear retinoid receptors (RARs and/or RXRs). In this study we investigated age-related alteration in both RAR and RXR receptor subtypes gene expression and tissue transglutaminase (tTG) activity before and after supplementation with 13-cis retinoic acid (13cRA) in human peripheral blood mononuclear cells (PBMCs). Healthy men (40) were divided in two groups according to their age (young group: 26.1+/-4.1 years and old group: 65.4+/-3.8 years). Each volunteer received 13cRA (Curacné), 0.5mg/(kgday)) during a period of 4 weeks. We have shown that RXRbeta expression was decreased significantly (p=0.0108) in PBMCs of elderly men when compared to that of young volunteers. Distribution of retinoic acid receptor subtype expression in PBMCs was found in the order: RXRbeta>RARgamma>RXRalpha>RARalpha. The tTG activity in PBMCs reflected a trend to be enhanced after 13-cis retinoic acid supplementation. In conclusion, we demonstrate a significant decrease in the expression of RXRbeta subtype of rexinoid receptors in PBMCs of healthy elderly men. Our data suggest that in healthy elderly men reduction of RXRbeta expression in PBMCs might be a common feature of physiological senescence.

  7. Effects of retinoic acids on the dendritic morphology of cultured hippocampal neurons.

    PubMed

    Liu, Ying; Kagechika, Hiroyuki; Ishikawa, Junko; Hirano, Hitoshi; Matsukuma, Satoshi; Tanaka, Kazuko; Nakamura, Shoji

    2008-08-01

    Vitamin A-derived retinoic acids (RAs) are known to exert a variety of biological actions, including modulatory effects on cell differentiation and apoptosis. A recent study has demonstrated that 13-cis-RA and all-trans-RA suppressed neurogenesis in the dentate gyrus of the hippocampus in adult mice. The present experiments were performed to see whether 13-cis-RA and all-trans-RA could alter the dendritic morphology of cultured hippocampal neurons via RA receptors: retinoic acid receptor (RAR) and retinoid X receptor (RXR). High doses of 13-cis-RA and all-trans-RA exerted a negative effect on the cultured hippocampal neurons, while a low dose of 13-cis-RA but not all-trans-RA caused a positive effect. The negative changes induced by 13-cis-RA and all-trans-RA were antagonized by RXR antagonists and RAR antagonists, respectively. The positive changes induced by a low dose of 13-cis-RA were blocked by both RXR antagonists and RAR antagonists. These results suggest that RAs at high concentrations cause a negative effect on the dendritic morphology of cultured hippocampal neurons through RA receptors, while RAs at low concentrations exert a positive influence on cultured hippocampal neurons.

  8. Cloning retinoid and peroxisome proliferator-activated nuclear receptors of the Pacific oyster and in silico binding to environmental chemicals

    PubMed Central

    Vogeler, Susanne; Galloway, Tamara S.; Isupov, Michail

    2017-01-01

    Disruption of nuclear receptors, a transcription factor superfamily regulating gene expression in animals, is one proposed mechanism through which pollution causes effects in aquatic invertebrates. Environmental pollutants have the ability to interfere with the receptor’s functions through direct binding and inducing incorrect signals. Limited knowledge of invertebrate endocrinology and molecular regulatory mechanisms, however, impede the understanding of endocrine disruptive effects in many aquatic invertebrate species. Here, we isolated three nuclear receptors of the Pacific oyster, Crassostrea gigas: two isoforms of the retinoid X receptor, CgRXR-1 and CgRXR-2, a retinoic acid receptor ortholog CgRAR, and a peroxisome proliferator-activated receptor ortholog CgPPAR. Computer modelling of the receptors based on 3D crystal structures of human proteins was used to predict each receptor’s ability to bind to different ligands in silico. CgRXR showed high potential to bind and be activated by 9-cis retinoic acid and the organotin tributyltin (TBT). Computer modelling of CgRAR revealed six residues in the ligand binding domain, which prevent the successful interaction with natural and synthetic retinoid ligands. This supports an existing theory of loss of retinoid binding in molluscan RARs. Modelling of CgPPAR was less reliable due to high discrepancies in sequence to its human ortholog. Yet, there are suggestions of binding to TBT, but not to rosiglitazone. The effect of potential receptor ligands on early oyster development was assessed after 24h of chemical exposure. TBT oxide (0.2μg/l), all-trans retinoic acid (ATRA) (0.06 mg/L) and perfluorooctanoic acid (20 mg/L) showed high effects on development (>74% abnormal developed D-shelled larvae), while rosiglitazone (40 mg/L) showed no effect. The results are discussed in relation to a putative direct (TBT) disruption effect on nuclear receptors. The inability of direct binding of ATRA to CgRAR suggests either a

  9. Ethanol impairs activation of retinoic acid receptors in cerebellar granule cells in a rodent model of fetal alcohol spectrum disorders.

    PubMed

    Kumar, Ambrish; Singh, Chandra K; DiPette, Donald D; Singh, Ugra S

    2010-05-01

    Ethanol is the main addictive and neurotoxic constituent of alcohol. Ethanol exposure during embryonic development causes dysfunction of the central nervous system (CNS) and leads to fetal alcohol spectrum disorders. The cerebellum is one of the CNS regions that are particularly vulnerable to ethanol toxic effects. Retinoic acid (RA) is a physiologically active metabolite of vitamin A that is locally synthesized in the cerebellum. Studies have shown that RA is required for neuronal development, but it remains unknown if ethanol impairs RA signaling and thus induces neuronal malformations. In this study, we tested the hypothesis that ethanol impairs the expression and activation of RA receptors in cerebellum and in cerebellar granule cells. The cerebellum of ethanol unexposed and exposed pups was used to study the expression of retinoic acid receptors (RARs or RXRs) by immunohistochemistry and by Western blot analysis. We also studied the effect of ethanol on expression of RA receptors in the cerebellar granule cells. Activation of RA receptors (DNA-binding activities) in response to high-dose ethanol was determined by electrophoretic mobility shift and supershift assays. Findings from these studies demonstrated that ethanol exposure reduced the expression of RARalpha/gamma while it increased the expression of RXRalpha/gamma in the cerebellum and in cerebellar granule neurons. Immuno-histological studies further strengthened the expression pattern of RA receptors in response to ethanol. The DNA-binding activity of RARs was reduced, while DNA-binding activity of RXRs was increased in response to ethanol exposure. For the first time, our studies have demonstrated that high-dose ethanol affects the expression and activation of RA receptors, which could impair the signaling events and induce harmful effects on the survival and differentiation of cerebellar granule cells. Taken together, these findings could provide insight into the treatment options for brain defects

  10. HDAC2 phosphorylation-dependent Klf5 deacetylation and RARα acetylation induced by RAR agonist switch the transcription regulatory programs of p21 in VSMCs

    PubMed Central

    Zheng, Bin; Han, Mei; Shu, Ya-nan; Li, Ying-jie; Miao, Sui-bing; Zhang, Xin-hua; Shi, Hui-jing; Zhang, Tian; Wen, Jin-kun

    2011-01-01

    Abnormal proliferation of vascular smooth muscle cells (VSMCs) occurs in hypertension, atherosclerosis and restenosis after angioplasty, leading to pathophysiological vascular remodeling. As an important growth arrest gene, p21 plays critical roles in vascular remodeling. Regulation of p21 expression by retinoic acid receptor (RAR) and its ligand has important implications for control of pathological vascular remodeling. Nevertheless, the mechanism of RAR-mediated p21 expression in VSMCs remains poorly understood. Here, we show that, under basal conditions, RARα forms a complex with histone deacetylase 2 (HDAC2) and Krüppel-like factor 5 (Klf5) at the p21 promoter to inhibit its expression. Upon RARα agonist stimulation, HDAC2 is phosphorylated by CK2α. Phosphorylation of HDAC2, on the one hand, promotes its dissociation from RARα, thus allowing the liganded-RARα to interact with co-activators; on the other hand, it increases its interaction with Klf5, thus leading to deacetylation of Klf5. Deacetylation of Klf5 facilitates its dissociation from the p21 promoter, relieving its repressive effect on the p21 promoter. Interference with HDAC2 phosphorylation by either CK2α knockdown or the use of phosphorylation-deficient mutant of HDAC2 prevents the dissociation of Klf5 from the p21 promoter and impairs RAR agonist-induced p21 activation. Our results reveal a novel mechanism involving a phosphorylation-deacetylation cascade that functions to remove the basal repression complex from the p21 promoter upon RAR agonist treatment, allowing for optimum agonist-induced p21 expression. PMID:21383775

  11. The retinoic acid receptor agonist Am80 increases mucosal inflammation in an IL-6 dependent manner during Trichuris muris infection.

    PubMed

    Hurst, Rebecca J M; De Caul, Adam; Little, Matthew C; Kagechika, Hiroyuki; Else, Kathryn J

    2013-11-01

    Vitamin A metabolites, such as all-trans-retinoic acid (RA) that act through the nuclear receptor; retinoic acid receptor (RAR), have been shown to polarise T cells towards Th2, and to be important in resistance to helminth infections. Co-incidentally, people harbouring intestinal parasites are often supplemented with vitamin A, as both vitamin A deficiency and parasite infections often occur in the same regions of the globe. However, the impact of vitamin A supplementation on gut inflammation caused by intestinal parasites is not yet completely understood. Here, we use Trichuris muris, a helminth parasite that buries into the large intestine of mice causing mucosal inflammation, as a model of both human trichuriasis and IBD, treat with an RARα/β agonist (Am80) and quantify the ensuing pathological changes in the gut. Critically, we show, for the first time, that rather than playing an anti-inflammatory role, Am80 actually exacerbates helminth-driven inflammation, demonstrated by an increased colonic crypt length and a significant CD4(+) T cell infiltrate. Further, we established that the Am80-driven crypt hyperplasia and CD4(+) T cell infiltrate were dependent on IL-6, as both were absent in Am80-treated IL-6 knock-out mice. This study presents novel data showing a pro-inflammatory role of RAR ligands in T. muris infection, and implies an undesirable effect for the administration of vitamin A during chronic helminth infection.

  12. Deflation-activated receptors, not classical inflation-activated receptors, mediate the Hering-Breuer deflation reflex.

    PubMed

    Yu, Jerry

    2016-11-01

    Many airway sensory units respond to both lung inflation and deflation. Whether those responses to opposite stimuli come from one sensor (one-sensor theory) or more than one sensor (multiple-sensor theory) is debatable. One-sensor theory is commonly presumed in the literature. This article proposes a multiple-sensor theory in which a sensory unit contains different sensors for sensing different forces. Two major types of mechanical sensors operate in the lung: inflation- and deflation-activated receptors (DARs). Inflation-activated sensors can be further divided into slowly adapting receptors (SARs) and rapidly adapting receptors (RARs). Many SAR and RAR units also respond to lung deflation because they contain DARs. Pure DARs, which respond to lung deflation only, are rare in large animals but are easily identified in small animals. Lung deflation-induced reflex effects previously attributed to RARs should be assigned to DARs (including pure DARs and DARs associated with SARs and RARs) if the multiple-sensor theory is accepted. Thus, based on the information, it is proposed that activation of DARs can attenuate lung deflation, shorten expiratory time, increase respiratory rate, evoke inspiration, and cause airway secretion and dyspnea.

  13. Refractory Anemia with Ring Sideroblasts (RARS) and RARS with Thrombocytosis (RARS-T) – “2017 Update on Diagnosis, Risk-stratification, and Management”

    PubMed Central

    Patnaik, Mrinal M.; Tefferi, Ayalew

    2017-01-01

    Disease Overview Ring sideroblasts (RS) are erythroid precursors with abnormal perinuclear mitochondrial iron accumulation. Two myeloid neoplasms defined by the presence of RS, include refractory anemia with ring sideroblasts (RARS), now classified under myelodysplastic syndromes with RS (MDS-RS) and RARS with thrombocytosis (RARS-T); now called myelodysplastic/myeloproliferative neoplasm with RS and thrombocytosis (MDS/MPN-RS-T). Diagnosis MDS-RS is a lower risk MDS, with single or multilineage dysplasia (SLD/MLD), <5% bone marrow (BM) blasts and ≥15% BM RS (≥5% in the presence of SF3B1 mutations). MDS/MPN-RS-T, now a formal entity in the MDS/MPN overlap syndromes, has diagnostic features of MDS-RS-SLD, along with a platelet count ≥ 450 × 10(9)/L and large atypical megakaryocytes (similar to BCR-ABL1 negative MPN). Mutations and Karyotype Mutations in SF3B1 are seen in ≥80% of patients with MDS-RS-SLD and MDS/MPN-RS-T, and strongly correlate with the presence of BM RS; MDS/MPN-RS-T patients also demonstrate JAK2V617F, ASXL1, DNMT3A, SETBP1, and TET2 mutations; with ASXL1/SETBP1 mutations adversely impacting survival. Cytogenetic abnormalities are uncommon in both diseases. Risk stratification Most patients with MDS-RS-SLD are stratified into lower risk groups by the revised-International Prognostic Scoring System (R-IPSS). Disease outcome in MDS/MPN-RS-T is better than that of MDS-RS-SLD, but worse than that of essential thrombocythemia. Both diseases have a low risk of leukemic transformation. Treatment Anemia and iron overload are complications seen in both and are managed similar to lower risk MDS and MPN. Aspirin therapy is reasonable in MDS/MPN-RS-T, especially in the presence of JAK2V617F, but the value of platelet-lowering drugs is uncertain. PMID:28188970

  14. The efficacy of 9-cis retinoic acid in experimental models of cancer.

    PubMed

    Gottardis, M M; Lamph, W W; Shalinsky, D R; Wellstein, A; Heyman, R A

    1996-01-01

    9-cis retinoic acid (9-cis RA) is a retinoid receptor pan-agonist that binds with high affinity to both retinoic acid receptors (RARs) and retinoid X receptors (RXRs). Using a variety of in vivo and in vitro cancer models, we present experimental data that 9-cis RA has activity as a potential chemotherapeutic agent. Treatment of the human promyelocytic leukemia cell line HL-60 with 9-cis RA decreases cell proliferation, increases cell differentiation, and increases apoptosis. Induction of apoptosis correlates with an increase in tissue transglutaminase (type II) activity. In vivo, 9-cis RA induces complete tumor regression of an early passage human lip squamous cell carcinoma xenograft. Finally, 9-cis RA inhibits the anchorage-independent growth of the human breast cancer cell lines MCF-7 and LY2 (an antiestrogen-resistant MCF-7 variant). Transient co-transfection assays indicate that 9-cis RA inhibits estrogen receptor transcription of an ERE-tk-LUC reporter through RAR or RXR receptors. These data suggest that retinoid receptors can antagonize estrogen-dependent transcription and provides one possible mechanism for the inhibition of cell growth by 9-cis RA in breast cancer cell lines. In summary, these findings present evidence that 9-cis RA has a wide range of activities in human cancer models.

  15. Tissue specific expression of the retinoic acid receptor-beta 2: regulation by short open reading frames in the 5'-noncoding region

    PubMed Central

    1994-01-01

    The 40-S subunit of eukaryotic ribosomes binds to the capped 5'-end of mRNA and scans for the first AUG in a favorable sequence context to initiate translation. Most eukaryotic mRNAs therefore have a short 5'- untranslated region (5'-UTR) and no AUGs upstream of the translational start site; features that seem to assure efficient translation. However, approximately 5-10% of all eukaryotic mRNAs, particularly those encoding for regulatory proteins, have complex leader sequences that seem to compromise translational initiation. The retinoic-acid- receptor-beta 2 (RAR beta 2) mRNA is such a transcript with a long (461 nucleotides) 5'-UTR that contains five, partially overlapping, upstream open reading frames (uORFs) that precede the major ORF. We have begun to investigate the function of this complex 5'-UTR in transgenic mice, by introducing mutations in the start/stop codons of the uORFs in RAR beta 2-lacZ reporter constructs. When we compared the expression patterns of mutant and wild-type constructs we found that these mutations affected expression of the downstream RAR beta 2-ORF, resulting in an altered regulation of RAR beta 2-lacZ expression in heart and brain. Other tissues were unaffected. RNA analysis of adult tissues demonstrated that the uORFs act at the level of translation; adult brains and hearts of transgenic mice carrying a construct with either the wild-type or a mutant UTR, had the same levels of mRNA, but only the mutant produced protein. Our study outlines an unexpected role for uORFs: control of tissue-specific and developmentally regulated gene expression. PMID:7962071

  16. The retinoic acid signaling pathway regulates anterior/posterior patterning in the nerve cord and pharynx of amphioxus, a chordate lacking neural crest.

    PubMed

    Escriva, Hector; Holland, Nicholas D; Gronemeyer, Hinrich; Laudet, Vincent; Holland, Linda Z

    2002-06-01

    Amphioxus, the closest living invertebrate relative of the vertebrates, has a notochord, segmental axial musculature, pharyngeal gill slits and dorsal hollow nerve cord, but lacks neural crest. In amphioxus, as in vertebrates, exogenous retinoic acid (RA) posteriorizes the embryo. The mouth and gill slits never form, AmphiPax1, which is normally downregulated where gill slits form, remains upregulated and AmphiHox1 expression shifts anteriorly in the nerve cord. To dissect the role of RA signaling in patterning chordate embryos, we have cloned the single retinoic acid receptor (AmphiRAR), retinoid X receptor (AmphiRXR) and an orphan receptor (AmphiTR2/4) from amphioxus. AmphiTR2/4 inhibits AmphiRAR-AmphiRXR-mediated transactivation in the presence of RA by competing for DR5 or IR7 retinoic acid response elements (RAREs). The 5' untranslated region of AmphiTR2/4 contains an IR7 element, suggesting possible auto- and RA-regulation. The patterns of AmphiTR2/4 and AmphiRAR expression during embryogenesis are largely complementary: AmphiTR2/4 is strongly expressed in the cerebral vesicle (homologous to the diencephalon plus anterior midbrain), while AmphiRAR expression is high in the equivalent of the hindbrain and spinal cord. Similarly, while AmphiTR2/4 is expressed most strongly in the anterior and posterior thirds of the endoderm, the highest AmphiRAR expression is in the middle third. Expression of AmphiRAR is upregulated by exogenous RA and completely downregulated by the RA antagonist BMS009. Moreover, BMS009 expands the pharynx posteriorly; the first three gill slit primordia are elongated and shifted posteriorly, but do not penetrate, and additional, non-penetrating gill slit primordia are induced. Thus, in an organism without neural crest, initiation and penetration of gill slits appear to be separate events mediated by distinct levels of RA signaling in the pharyngeal endoderm. Although these compounds have little effect on levels of AmphiTR2/4 expression, RA

  17. The retinoic acid signaling pathway regulates anterior/posterior patterning in the nerve cord and pharynx of amphioxus, a chordate lacking neural crest

    NASA Technical Reports Server (NTRS)

    Escriva, Hector; Holland, Nicholas D.; Gronemeyer, Hinrich; Laudet, Vincent; Holland, Linda Z.

    2002-01-01

    Amphioxus, the closest living invertebrate relative of the vertebrates, has a notochord, segmental axial musculature, pharyngeal gill slits and dorsal hollow nerve cord, but lacks neural crest. In amphioxus, as in vertebrates, exogenous retinoic acid (RA) posteriorizes the embryo. The mouth and gill slits never form, AmphiPax1, which is normally downregulated where gill slits form, remains upregulated and AmphiHox1 expression shifts anteriorly in the nerve cord. To dissect the role of RA signaling in patterning chordate embryos, we have cloned the single retinoic acid receptor (AmphiRAR), retinoid X receptor (AmphiRXR) and an orphan receptor (AmphiTR2/4) from amphioxus. AmphiTR2/4 inhibits AmphiRAR-AmphiRXR-mediated transactivation in the presence of RA by competing for DR5 or IR7 retinoic acid response elements (RAREs). The 5' untranslated region of AmphiTR2/4 contains an IR7 element, suggesting possible auto- and RA-regulation. The patterns of AmphiTR2/4 and AmphiRAR expression during embryogenesis are largely complementary: AmphiTR2/4 is strongly expressed in the cerebral vesicle (homologous to the diencephalon plus anterior midbrain), while AmphiRAR expression is high in the equivalent of the hindbrain and spinal cord. Similarly, while AmphiTR2/4 is expressed most strongly in the anterior and posterior thirds of the endoderm, the highest AmphiRAR expression is in the middle third. Expression of AmphiRAR is upregulated by exogenous RA and completely downregulated by the RA antagonist BMS009. Moreover, BMS009 expands the pharynx posteriorly; the first three gill slit primordia are elongated and shifted posteriorly, but do not penetrate, and additional, non-penetrating gill slit primordia are induced. Thus, in an organism without neural crest, initiation and penetration of gill slits appear to be separate events mediated by distinct levels of RA signaling in the pharyngeal endoderm. Although these compounds have little effect on levels of AmphiTR2/4 expression, RA

  18. A forward chemical screen in zebrafish identifies a retinoic acid derivative with receptor specificity.

    PubMed

    Das, Bhaskar C; McCartin, Kellie; Liu, Ting-Chun; Peterson, Randall T; Evans, Todd

    2010-04-02

    Retinoids regulate key developmental pathways throughout life, and have potential uses for differentiation therapy. It should be possible to identify novel retinoids by coupling new chemical reactions with screens using the zebrafish embryonic model. We synthesized novel retinoid analogues and derivatives by amide coupling, obtaining 80-92% yields. A small library of these compounds was screened for bioactivity in living zebrafish embryos. We found that several structurally related compounds significantly affect development. Distinct phenotypes are generated depending on time of exposure, and we characterize one compound (BT10) that produces specific cardiovascular defects when added 1 day post fertilization. When compared to retinoic acid (ATRA), BT10 shows similar but not identical changes in the expression pattern of embryonic genes that are known targets of the retinoid pathway. Reporter assays determined that BT10 interacts with all three RAR receptor sub-types, but has no activity for RXR receptors, at all concentrations tested. Our screen has identified a novel retinoid with specificity for retinoid receptors. This lead compound may be useful for manipulating components of retinoid signaling networks, and may be further derivatized for enhanced activity.

  19. Nutrigenomic regulation of adipose tissue development --- role of retinoic acid: A review

    PubMed Central

    Wang, Bo; Yang, Qiyuan; Harris, Corrine L.; Nelson, Mark L.; Busboom, Jan R.; Zhu, Mei-Jun; Du, Min

    2016-01-01

    To improve the efficiency of animal production, livestock have been extensively selected or managed to reduce fat accumulation and increase lean growth, which reduces intramuscular or marbling fat content. To enhance marbling, a better understanding of the mechanisms regulating adipogenesis is needed. Vitamin A has recently been shown to have a profound impact on all stages of adipogenesis. Retinoic acid, an active metabolite of vitamin A, activates both retinoic acid receptors (RAR) and retinoid X receptors (RXR), inducing epigenetic changes in key regulatory genes governing adipogenesis. Additionally, Vitamin D and folates interact with the retinoic acid receptors to regulate adipogenesis. In this review, we discuss nutritional regulation of adipogenesis, focusing on retinoic acid and its impact on epigenetic modifications of key adipogenic genes. PMID:27086067

  20. LE135, a retinoid acid receptor antagonist, produces pain through direct activation of TRP channels.

    PubMed

    Yin, Shijin; Luo, Jialie; Qian, Aihua; Yu, Weihua; Hu, Hongzhen

    2014-03-01

    Retinoids, through their activation of retinoic acid receptors (RARs) and retinoid X receptors, regulate diverse cellular processes, and pharmacological intervention in their actions has been successful in the treatment of skin disorders and cancers. Despite the many beneficial effects, administration of retinoids causes irritating side effects with unknown mechanisms. Here, we demonstrate that LE135 [4-(7,8,9,10-tetrahydro-5,7,7,10,10-pentamethyl-5H-benzo[e]naphtho[2,3-b][1,4]diazepin-13-yl)benzoic acid], a selective antagonist of RARβ , is a potent activator of the capsaicin (TRPV1) and wasabi (TRPA1) receptors, two critical pain-initiating cation channels. We performed to investigate the excitatory effects of LE135 on TRPV1 and TRPA1 channels expressed in HEK293T cells and in dorsal root ganglia neurons with calcium imaging and patch-clamp recordings. We also used site-directed mutagenesis of the channels to determine the structural basis of LE135-induced activation of TRPV1 and TRPA1 channels and behavioural testing to examine if pharmacological inhibition and genetic deletion of the channels affected LE135-evoked pain-related behaviours. LE135 activated both the capsaicin receptor (TRPV1) and the allyl isothiocyanate receptor (TRPA1) heterologously expressed in HEK293T cells and endogenously expressed by sensory nociceptors. Mutations disrupting the capsaicin-binding site attenuated LE135 activation of TRPV1 channels and a single mutation (K170R) eliminated TRPA1 activity evoked by LE135. Intraplantar injection of LE135 evoked pain-related behaviours. Both TRPV1 and TRPA1 channels were involved in LE135-elicited pain-related responses, as shown by pharmacological and genetic ablation studies. This blocker of retinoid acid signalling also exerted non-genomic effects through activating the pain-initiating TRPV1 and TRPA1 channels. © 2013 The British Pharmacological Society.

  1. CW laser damage testing of RAR nano-textured fused silica and YAG

    NASA Astrophysics Data System (ADS)

    MacLeod, Bruce D.; Hobbs, Douglas S.; Manni, Anthony D.; Sabatino, Ernest; Bernot, David M.; DeFrances, Sage; Randi, Joseph A.; Thomas, Jeffrey

    2017-11-01

    A study of the continuous wave (CW) laser induced damage threshold (LiDT) of fused silica and yttrium aluminum garnet (YAG) optics was conducted to further illustrate the enhanced survivability within high power laser systems of an anti-reflection (AR) treatment consisting of randomly distributed surface relief nanostructures (RAR). A series of three CW LiDT tests using the 1070nm wavelength, 16 KW fiber laser test bed at Penn State Electro-Optic Center (PSEOC) were designed and completed, with improvements in the testing protocol, areal coverage, and maximum exposure intensities implemented between test cycles. Initial results for accumulated power, stationary site exposures of RAR nano-textured optics showed no damage and low surface temperatures similar to the control optics with no AR treatment. In contrast, optics with thin-film AR coatings showed high surface temperatures consistent with absorption by the film layers. Surface discriminating absorption measurements made using the Photothermal Common-path Interferometry (PCI) method, showed zero added surface absorption for the RAR nanotextured optics, and absorption levels in the 2-5 part per million range for thin-film AR coated optics. In addition, the surface absorption of thin-film AR coatings was also found to have localized absorption spikes that are likely pre-cursors for damage. Subsequent CW LiDT testing protocol included raster scanning an increased intensity focused beam over the test optic surface where it was found that thin-film AR coated optics damaged at intensities in the 2 to 5 MW/cm2 range with surface temperatures over 250C during the long-duration exposures. Significantly, none of the 10 RAR nano-textured fused silica optics tested could be damaged up to the maximum system intensity of 15.5 MW/cm2, and surface temperatures remained low. YAG optics tested during the final cycle exhibited a similar result with RAR nano-textured surfaces surviving intensities over 3 times higher than thin

  2. Ischemic preconditioning inhibits over-expression of arginyl-tRNA synthetase gene Rars in ischemia-injured neurons.

    PubMed

    Shen, Yin; Zhao, Hong-Yang; Wang, Hai-Jun; Wang, Wen-Liang; Zhang, Li-Zhi; Fu, Rong

    2016-08-01

    The expression changes of Rars gene in ischemia-injured neurons were investigated by detecting its translational product arginyl-tRNA synthetase (ArgRS), and the inhibitory effects of ischemic preconditioning (IPC) on Rars gene were explored. Both IPC model and prolonged ischemia (PI) model were established by using the classic oxygen glucose deprivation (OGD) method. The primary cultured neurons were assigned into the following groups: the experimental group (IPC+PI group), undergoing PI after a short period of IPC; the conditional control group (PI control group), subjected to PI without IPC; blank control group, the normally cultured neurons. The Rars transcriptional activities and ArgRS expression levels were measured at different time points after re-oxygenation (3 h/6 h/12 h/24 h). Data were collected and statistically analyzed. Compared to the blank control group, the Rars activities and ArgRS levels were significantly increased in PI control group, peaking at the time point of 6 h after re-oxygenation. Rars activities and ArgRS levels were significantly lower in the experimental group than in the PI control group at different time points after re-oxygenation. PI insult can induce an escalating activity of Rars and lead to ArgRS over-expression in primary cultured neurons. IPC can inhibit the increased Rars activity and down-regulate ArgRS expression of ischemia-insulted neurons. This mechanism may confer ischemic tolerance on neurons.

  3. Substance P contributes to rapidly adapting receptor responses to pulmonary venous congestion in rabbits.

    PubMed

    Bonham, A C; Kott, K S; Ravi, K; Kappagoda, C T; Joad, J P

    1996-05-15

    1. This study tested the hypothesis that substance P stimulates rapidly adapting receptors (RARs), contributes to the increase in RAR activity produced by mild pulmonary congestion, and evokes an augmented response from RARs when combined with near-threshold levels of pulmonary congestion. 2. RAR activity, peak tracheal pressure, arterial blood pressure and left atrial pressure were measured in paralysed, anaesthetized and ventilated rabbits. Substance P was given i.v. in one-half log incremental doses to a maximum of 3 micrograms kg-1. Mild pulmonary congestion was produced by inflating a balloon in the left atrium to increase left atrial pressure by 5 mmHg. Near-threshold levels of pulmonary congestion were produced by increasing left atrial pressure by 2 mmHg. 3. Substance P produced dose-dependent increases in RAR activity. The highest dose given increased the activity from 1.3 +/- 0.5 to 11.0 +/- 3.1 impulses bin-1. Increases in left atrial pressure of 5 mmHg increased RAR activity from 3.8 +/- 1.4 to 14.7 +/- 3.9 impulses bin-1. Blockade of NK1 receptors with CP 96345 significantly attenuated RAR responses to substance P and to mild pulmonary congestion. 4. Doses of substance P, which alone had no effect, stimulated the RARs when delivered during near-threshold levels of pulmonary congestion. 5. The findings suggest that substance P augments the stimulatory effect of mild pulmonary congestion on RAR activity, most probably by enhancing hydraulically induced microvascular leak.

  4. The role of retinoic acid receptors and their cognate ligands in reproduction in a context of triorganotin based endocrine disrupting chemicals.

    PubMed

    Macejova, Dana; Toporova, L; Brtko, J

    2016-07-01

    Retinoic acid (RA), an active form of vitamin A, regulates the embryonic development, male and female reproduction and induces important effects on the cell development, proliferation, and differentiation. These effects are mediated by the retinoid (RAR) and rexinoid nuclear receptors (RXR), which are considered to be a ligand-activated, DNA-binding, trans-acting, and transcription-modulating proteins, involved in a general molecular mechanism responsible for the transcriptional responses in target genes. Organotin compounds are typical environmental contaminants and suspected endocrine disrupting substances. They may affect processes of reproductive system in mammals, predominantly via nuclear receptor signaling pathways. Triorganotins, such as tributyltin chloride (TBTCl) and triphenyltin chloride (TPTCl), are capable to bind to RXR molecules, and thus represent potent agonists of RXR subtypes of nuclear receptors not sharing any structural characteristics with endogenous ligands of nuclear receptors. Th is article summarizes selected effects of biologically active retinoids and rexinoids on both male and female reproduction and also deals with the effects of organotin compounds evoking endocrine disrupting actions in reproduction.

  5. Substance P contributes to rapidly adapting receptor responses to pulmonary venous congestion in rabbits.

    PubMed Central

    Bonham, A C; Kott, K S; Ravi, K; Kappagoda, C T; Joad, J P

    1996-01-01

    1. This study tested the hypothesis that substance P stimulates rapidly adapting receptors (RARs), contributes to the increase in RAR activity produced by mild pulmonary congestion, and evokes an augmented response from RARs when combined with near-threshold levels of pulmonary congestion. 2. RAR activity, peak tracheal pressure, arterial blood pressure and left atrial pressure were measured in paralysed, anaesthetized and ventilated rabbits. Substance P was given i.v. in one-half log incremental doses to a maximum of 3 micrograms kg-1. Mild pulmonary congestion was produced by inflating a balloon in the left atrium to increase left atrial pressure by 5 mmHg. Near-threshold levels of pulmonary congestion were produced by increasing left atrial pressure by 2 mmHg. 3. Substance P produced dose-dependent increases in RAR activity. The highest dose given increased the activity from 1.3 +/- 0.5 to 11.0 +/- 3.1 impulses bin-1. Increases in left atrial pressure of 5 mmHg increased RAR activity from 3.8 +/- 1.4 to 14.7 +/- 3.9 impulses bin-1. Blockade of NK1 receptors with CP 96345 significantly attenuated RAR responses to substance P and to mild pulmonary congestion. 4. Doses of substance P, which alone had no effect, stimulated the RARs when delivered during near-threshold levels of pulmonary congestion. 5. The findings suggest that substance P augments the stimulatory effect of mild pulmonary congestion on RAR activity, most probably by enhancing hydraulically induced microvascular leak. Images Figure 6 PMID:8735708

  6. [Efficiency of combined methods of hemorroid treatment using hal-rar and laser destruction].

    PubMed

    Rodoman, G V; Kornev, L V; Shalaeva, T I; Malushenko, R N

    2017-01-01

    To develop the combined method of treatment of hemorrhoids with arterial ligation under Doppler control and laser destruction of internal and external hemorrhoids. The study included 100 patients with chronic hemorrhoids stage II and III. Combined method of HAL-laser was used in study group, HAL RAR-technique in control group 1 and closed hemorrhoidectomy with linear stapler in control group 2. Сomparative evaluation of results in both groups was performed. Combined method overcomes the drawbacks of traditional surgical treatment and limitations in external components elimination which are inherent for HAL-RAR. Moreover, it has a higher efficiency in treating of hemorrhoids stage II-III compared with HAL-RAR and is equally safe and well tolerable for patients. This method does not increase the risk of recurrence, reduces incidence of complications and time of disability.

  7. LE135, a retinoid acid receptor antagonist, produces pain through direct activation of TRP channels

    PubMed Central

    Yin, Shijin; Luo, Jialie; Qian, Aihua; Yu, Weihua; Hu, Hongzhen

    2014-01-01

    Background and PurposeRetinoids, through their activation of retinoic acid receptors (RARs) and retinoid X receptors, regulate diverse cellular processes, and pharmacological intervention in their actions has been successful in the treatment of skin disorders and cancers. Despite the many beneficial effects, administration of retinoids causes irritating side effects with unknown mechanisms. Here, we demonstrate that LE135 [4-(7,8,9,10-tetrahydro-5,7,7,10,10-pentamethyl-5H-benzo[e]naphtho[2,3-b][1,4]diazepin-13-yl)benzoic acid], a selective antagonist of RARβ, is a potent activator of the capsaicin (TRPV1) and wasabi (TRPA1) receptors, two critical pain-initiating cation channels. Experimental ApproachWe performed to investigate the excitatory effects of LE135 on TRPV1 and TRPA1 channels expressed in HEK293T cells and in dorsal root ganglia neurons with calcium imaging and patch-clamp recordings. We also used site-directed mutagenesis of the channels to determine the structural basis of LE135-induced activation of TRPV1 and TRPA1 channels and behavioural testing to examine if pharmacological inhibition and genetic deletion of the channels affected LE135-evoked pain-related behaviours. Key ResultsLE135 activated both the capsaicin receptor (TRPV1) and the allyl isothiocyanate receptor (TRPA1) heterologously expressed in HEK293T cells and endogenously expressed by sensory nociceptors. Mutations disrupting the capsaicin-binding site attenuated LE135 activation of TRPV1 channels and a single mutation (K170R) eliminated TRPA1 activity evoked by LE135. Intraplantar injection of LE135 evoked pain-related behaviours. Both TRPV1 and TRPA1 channels were involved in LE135-elicited pain-related responses, as shown by pharmacological and genetic ablation studies. Conclusions and ImplicationsThis blocker of retinoid acid signalling also exerted non-genomic effects through activating the pain-initiating TRPV1 and TRPA1 channels. PMID:24308840

  8. Abscisic-acid-induced cellular apoptosis and differentiation in glioma via the retinoid acid signaling pathway.

    PubMed

    Zhou, Nan; Yao, Yu; Ye, Hongxing; Zhu, Wei; Chen, Liang; Mao, Ying

    2016-04-15

    Retinoid acid (RA) plays critical roles in regulating differentiation and apoptosis in a variety of cancer cells. Abscisic acid (ABA) and RA are direct derivatives of carotenoids and share structural similarities. Here we proposed that ABA may also play a role in cellular differentiation and apoptosis by sharing a similar signaling pathway with RA that may be involved in glioma pathogenesis. We reported for the first time that the ABA levels were twofold higher in low-grade gliomas compared with high-grade gliomas. In glioma tissues, there was a positive correlation between the ABA levels and the transcription of cellular retinoic acid-binding protein 2 (CRABP2) and a negative correlation between the ABA levels and transcription of fatty acid-binding protein 5 (FABP5). ABA treatment induced a significant increase in the expression of CRABP2 and a decrease in the expression of peroxisome proliferator-activated receptor (PPAR) in glioblastoma cells. Remarkably, both cellular apoptosis and differentiation were increased in the glioblastoma cells after ABA treatment. ABA-induced cellular apoptosis and differentiation were significantly reduced by selectively silencing RAR-α, while RAR-α overexpression exaggerated the ABA-induced effects. These results suggest that ABA may play a role in the pathogenesis of glioma by promoting cellular apoptosis and differentiation through the RA signaling pathway. © 2015 UICC.

  9. Genome-wide Analysis of RARβ Transcriptional Targets in Mouse Striatum Links Retinoic Acid Signaling with Huntington's Disease and Other Neurodegenerative Disorders.

    PubMed

    Niewiadomska-Cimicka, Anna; Krzyżosiak, Agnieszka; Ye, Tao; Podleśny-Drabiniok, Anna; Dembélé, Doulaye; Dollé, Pascal; Krężel, Wojciech

    2017-07-01

    Retinoic acid (RA) signaling through retinoic acid receptors (RARs), known for its multiple developmental functions, emerged more recently as an important regulator of adult brain physiology. How RAR-mediated regulation is achieved is poorly known, partly due to the paucity of information on critical target genes in the brain. Also, it is not clear how reduced RA signaling may contribute to pathophysiology of diverse neuropsychiatric disorders. We report the first genome-wide analysis of RAR transcriptional targets in the brain. Using chromatin immunoprecipitation followed by high-throughput sequencing and transcriptomic analysis of RARβ-null mutant mice, we identified genomic targets of RARβ in the striatum. Characterization of RARβ transcriptional targets in the mouse striatum points to mechanisms through which RAR may control brain functions and display neuroprotective activity. Namely, our data indicate with statistical significance (FDR 0.1) a strong contribution of RARβ in controlling neurotransmission, energy metabolism, and transcription, with a particular involvement of G-protein coupled receptor (p = 5.0e -5 ), cAMP (p = 4.5e -4 ), and calcium signaling (p = 3.4e -3 ). Many identified RARβ target genes related to these pathways have been implicated in Alzheimer's, Parkinson's, and Huntington's disease (HD), raising the possibility that compromised RA signaling in the striatum may be a mechanistic link explaining the similar affective and cognitive symptoms in these diseases. The RARβ transcriptional targets were particularly enriched for transcripts affected in HD. Using the R6/2 transgenic mouse model of HD, we show that partial sequestration of RARβ in huntingtin protein aggregates may account for reduced RA signaling reported in HD.

  10. A retinoic acid receptor β2 agonist reduces hepatic stellate cell activation in nonalcoholic fatty liver disease.

    PubMed

    Trasino, Steven E; Tang, Xiao-Han; Jessurun, Jose; Gudas, Lorraine J

    2016-10-01

    Hepatic stellate cells (HSCs) are an important cellular target for the development of novel pharmacological therapies to prevent and treat nonalcoholic fatty liver diseases (NAFLD). Using a high fat diet (HFD) model of NAFLD, we sought to determine if synthetic selective agonists for retinoic acid receptor β2 (RARβ2) and RARγ can mitigate HSC activation and HSC relevant signaling pathways during early stages of NAFLD, before the onset of liver injury. We demonstrate that the highly selective RARβ2 agonist, AC261066, can reduce the activation of HSCs, marked by decreased HSC expression of α-smooth muscle actin (α-SMA), in mice with HFD-induced NAFLD. Livers of HFD-fed mice treated with AC261066 exhibited reduced steatosis, oxidative stress, and expression of pro-inflammatory mediators, such as tumor necrosis factor-alpha (TNFα), interleukin 1β (IL-1β), and monocyte chemotactic protein-1 (MCP-1). Kupffer cell (macrophage) expression of transforming growth factor-β1 (TGF-β1), which plays a critical role in early HSC activation, was markedly reduced in AC261066-treated, HFD-fed mice. In contrast, HFD-fed mice treated with an RARγ agonist (CD1530) showed no decreases in steatosis, HSC activation, or Kupffer cell TGF-β1 levels. In conclusion, our data demonstrate that RARβ2 is an attractive target for development of NAFLD therapies. • Hepatic stellate cells (HSCs) are an important pharmacological target for the prevention of nonalcoholic fatty liver diseases (NAFLD). • Retinoids and retinoic acid receptors (RARs) possess favorable metabolic modulating properties. • We show that an agonist for retinoic acid receptor-β2 (RARβ2), but not RARγ, mitigates HSC activation and NAFLD.

  11. Arsenic as an Endocrine Disruptor: Arsenic Disrupts Retinoic Acid Receptor–and Thyroid Hormone Receptor–Mediated Gene Regulation and Thyroid Hormone–Mediated Amphibian Tail Metamorphosis

    PubMed Central

    Davey, Jennifer C.; Nomikos, Athena P.; Wungjiranirun, Manida; Sherman, Jenna R.; Ingram, Liam; Batki, Cavus; Lariviere, Jean P.; Hamilton, Joshua W.

    2008-01-01

    Background Chronic exposure to excess arsenic in drinking water has been strongly associated with increased risks of multiple cancers, diabetes, heart disease, and reproductive and developmental problems in humans. We previously demonstrated that As, a potent endocrine disruptor at low, environmentally relevant levels, alters steroid signaling at the level of receptor-mediated gene regulation for all five steroid receptors. Objectives The goal of this study was to determine whether As can also disrupt gene regulation via the retinoic acid (RA) receptor (RAR) and/or the thyroid hormone (TH) receptor (TR) and whether these effects are similar to previously observed effects on steroid regulation. Methods and results Human embryonic NT2 or rat pituitary GH3 cells were treated with 0.01–5 μM sodium arsenite for 24 hr, with or without RA or TH, respectively, to examine effects of As on receptor-mediated gene transcription. At low, noncytotoxic doses, As significantly altered RAR-dependent gene transcription of a transfected RAR response element–luciferase construct and the native RA-inducible cytochrome P450 CYP26A gene in NT2 cells. Likewise, low-dose As significantly altered expression of a transfected TR response element–luciferase construct and the endogenous TR-regulated type I deiodinase (DIO1) gene in a similar manner in GH3 cells. An amphibian ex vivo tail metamorphosis assay was used to examine whether endocrine disruption by low-dose As could have specific pathophysiologic consequences, because tail metamorphosis is tightly controlled by TH through TR. TH-dependent tail shrinkage was inhibited in a dose-dependent manner by 0.1– 4.0 μM As. Conclusions As had similar effects on RAR- and TR-mediated gene regulation as those previously observed for the steroid receptors, suggesting a common mechanism or action. Arsenic also profoundly affected a TR-dependent developmental process in a model animal system at very low concentrations. Because RAR and TH are

  12. Embryonic subcellular distribution of 13-cis- and all-trans-retinoic acid indicates differential cytosolic/nuclear localization.

    PubMed

    Rühl, R; Plum, C; Elmazar, M M; Nau, H

    2001-09-01

    Isotretinoin (13-cis-retinoic acid [13CRA], Accutane) is used for the treatment of dermatological diseases. Isotretinoin is, however, teratogenic in animals and humans. The mechanism of action of its teratogenicity is still not clearly identified. It has little or no binding properties to cytosolic retinoid-binding proteins or nuclear retinoid receptors (RAR, RXR). One hypothesis is that the teratogenicity of 2 approximately equipotent teratogenic doses of 13CRA and all-trans-retinoic acids (ATRA) could mainly be correlated to ATRA in the nuclei, where the retinoic acid receptors (RARs) are located. To test this hypothesis, female mice at gestational day 11 were treated with approximately equipotent teratogenic doses of 13-cis-retinoic acid (100 mg/kg orally) or all-trans-retinoic acid (10 mg/kg orally) and sacrificed 1 h and 4 h after administration. Embryos were homogenized and centrifuged into 4 fractions, and the purity of the fractions was tested by quantification of marker constituents for various cell compartments. We analyzed, by RP-HPLC, nuclear, mitochondrial, microsomal, and cytosolic fractions, as well as embryo homogenate and maternal plasma. After treatment with 13-cis-retinoic acid, this substance was mainly located in the nuclear fraction of the embryo (approximately 82%), whereas all-trans-retinoic acid, after ATRA treatment, was mainly located in the cytosolic supernatant (approximately 64%). The binding to cellular retinoid-binding protein (CRABP) may limit the access of ATRA to the nucleus, in contrast to 13CRA, which does not bind to CRABP. The concentration of ATRA in the nuclear fraction was similar after administration of either 13CRA or ATRA. The teratogenic activity of 13-cis-retinoic acid could therefore be explained by its access to the nucleus and its possible conversion to all-trans-retinoic acids, which will interact with the nuclear retinoid receptors.

  13. Retinoic Acid Receptor β: A Potential Therapeutic Target in Retinoic Acid Treatment of Endometrial Cancer.

    PubMed

    Tsuji, Keita; Utsunomiya, Hiroki; Miki, Yasuhiro; Hanihara, Mayu; Fue, Misaki; Takagi, Kiyoshi; Nishimoto, Mitsuo; Suzuki, Fumihiko; Yaegashi, Nobuo; Suzuki, Takashi; Ito, Kiyoshi

    2017-05-01

    Several studies have reported that retinoic acid (RA) might be used to treat malignancies. The effects of RA are mediated by the RA receptor (RAR), and RARα/RARβ especially acts as a tumor suppressor. However, little is known about its role in human endometrial cancer. In this study, we examined the effects of all-trans RA (ATRA) on progression of human endometrial cancer cell line, RL95-2 and Hec1A. We then examined the expression of RARα and RARβ in 50 endometrial cancer tissues by using immunohistochemistry. We found inhibitory effects of ATRA on cell proliferation, apoptosis, and migration in RL95-2 cells, but not in Hec1A cells. RARα or RARβ knockdown individually could not cancel out the inhibition of cell proliferation by ATRA in RL95-2 cells, but simultaneous knockdown of RARα and RARβ could block its effect on proliferation. RARα and RARβ knockdown dose dependently reduced the inhibition of migration by ATRA, but the effect was more pronounced with RARβ knockdown than with RARα knockdown. We confirmed that RARβ gene was directly regulated by ATRA in microarray and real-time reverse transcription polymerase chain reaction. Furthermore, the RARβ agonist (BMS453) significantly suppressed proliferation of RL95-2 cells. In immunohistochemical analysis, RARα expression was positively correlated with tumor grade, and RARβ showed the opposite tendency in endometrial cancer. Retinoic acid might have multiple antitumor effects, and RARβ may be a potent therapeutic target in RA treatment for endometrial cancers.

  14. Stimulation of pulmonary rapidly adapting receptors by inhaled wood smoke in rats

    PubMed Central

    Lai, C J; Kou, Y R

    1998-01-01

    The stimulation of pulmonary rapidly adapting receptors (RARs) by wood smoke was investigated. Impulses from seventy RARs were recorded in fifty-nine anaesthetized, open-chest and artificially ventilated rats; responses to delivery of 6 ml of wood smoke into the lungs were studied in sixty-one receptors whereas responses to histamine (10 or 100 μg kg−1, i.v.) were studied in the other nine. Delivery of wood smoke stimulated fifty-two of the sixty-one RARs studied. When stimulated, an intense burst of discharge was evoked within 1 or 2 s of smoke delivery. This increased activity quickly peaked in 1-3 s (Δ= 15.8 ± 1.6 impulses s−1; n = 61; mean ± s.e.m.), then declined and yet remained at a level higher than the baseline activity. The mean duration of the stimulation was 25.1 ± 2.7 s. In contrast, smoke delivery did not affect tracheal pressure. Peak responses of RARs to wood smoke were partially reduced by removal of smoke particulates and were largely attenuated by pretreatment with dimethylthiourea (DMTU, a hydroxyl radical scavenger), indomethacin (Indo, a cyclo-oxygenase inhibitor), or both DMTU and Indo (DMTU + Indo). Conversely, the peak responses of RARs were not significantly affected by pretreatment with isoprenaline (a bronchodilator) or vehicle for these chemicals. Additionally, pretreatment with DMTU, Indo, or DMTU + Indo did not significantly alter the RAR sensitivity to mechanical stimulation (constant-pressure lung inflation; 20 cmH2O). Of the nine RARs tested, six were stimulated by histamine and their sensitivity to this chemical irritant was not altered by pretreatment with DMTU + Indo. The results suggest that both the particulates and gas phases are responsible for, and both the hydroxyl radical and cyclo-oxygenase products are involved in, the stimulation of RARs by wood smoke. Furthermore, changes in lung mechanics following smoke delivery are not the cause of this afferent stimulation. PMID:9508820

  15. High altitude simulation, substance P and airway rapidly adapting receptor activity in rabbits.

    PubMed

    Bhagat, R; Yasir, A; Vashisht, A; Kulshreshtha, R; Singh, S B; Ravi, K

    2011-09-15

    To investigate whether there is a change in airway rapidly adapting receptor (RAR) activity during high altitude exposure, rabbits were placed in a high altitude simulation chamber (barometric pressure, 429 mm Hg). With 12 h exposure, when there was pulmonary congestion, an increase in basal RAR activity was observed. With 36 h exposure, when there was alveolar edema, there was a further increase in basal RAR activity. In these backgrounds, there was an increase in the sensitivity of the RARs to substance P (SP). To assess whether there was an increase in lung SP level, neutral endopeptidase activity was determined which showed a decrease in low barometric pressure exposed groups. It is concluded that along with the SP released, pulmonary congestion and edema produced, respectively by different durations of low barometric pressure exposure cause a progressive increase in RAR activity which may account for the respiratory symptoms reported in climbers who are unacclimatized. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Choguita Rarámuri (Tarahumara) Language Description and Documentation: A Guide to the Deposited Collection and Associated Materials

    ERIC Educational Resources Information Center

    Caballero, Gabriela

    2017-01-01

    Choguita Rarámuri (Tarahumara) is a Uto-Aztecan language spoken in Northern Mexico of great typological, theoretical, and historical significance. This paper presents an overview and background of the Choguita Rarámuri language description and documentation project and provides a guide to the documentary collection emerging from this project. This…

  17. Regeneration of the gut requires retinoic acid in the budding ascidian Polyandrocarpa misakiensis.

    PubMed

    Kaneko, Nagamoto; Katsuyama, You; Kawamura, Kazuo; Fujiwara, Shigeki

    2010-06-01

    The protochordate ascidian Polyandrocarpa misakiensis has a striking ability to regenerate. When the posterior half of the adult body is amputated, the anterior half completely loses the esophagus, stomach and intestine. These organs are reconstituted in a week. Histological observation revealed that the regeneration involves transdifferentiation of the atrial epithelium near the cut surface. The morphological features of the gut primordium were similar to those observed in the developing bud of this species. Inhibitors of the synthesis of retinoic acid (RA) suppressed the formation of the gut. 13-cis RA rescued the regenerates from the inhibitor-induced hypoplasia. These results suggest that RA is required for the regeneration of the gut. A gene encoding the RA receptor (Pm-RAR) and its target gene, TRAMP, were expressed in and around the regenerating gut. Pm-RAR-specific and TRAMP-specific double-stranded RNA molecules inhibited the regeneration of the gut, indicating that the RA signal is mediated at least in part by Pm-RAR and TRAMP. These results suggested that RA triggers the transdifferentiation of the atrial epithelium into the gut in regenerating animals, as it does during asexual reproduction.

  18. TaRAR1 and TaSGT1 associate with TaHsp90 to function in bread wheat (Triticum aestivum L.) seedling growth and stripe rust resistance.

    PubMed

    Wang, Guan-Feng; Fan, Renchun; Wang, Xianping; Wang, Daowen; Zhang, Xiangqi

    2015-04-01

    RAR1 and SGT1 are important co-chaperones of Hsp90. We previously showed that TaHsp90.1 is required for wheat seedling growth, and that TaHsp90.2 and TaHsp90.3 are essential for resistance (R) gene mediated resistance to stripe rust fungus. Here, we report the characterization of TaRAR1 and TaSGT1 genes in bread wheat. TaRAR1 and TaSGT1 each had three homoeologs, which were located on wheat groups 2 and 3 chromosomes, respectively. Strong inhibition of seedling growth was observed after silencing TaSGT1 but not TaRAR1. In contrast, decreasing the expression of TaRAR1 or TaSGT1 could all compromise R gene mediated resistance to stripe rust fungus infection. Protein-protein interactions were found among TaRAR1, TaSGT1 and TaHsp90. The N-terminus of TaHsp90, the CHORD-I and CHORD-II domains of TaRAR1 and the CS domain of TaSGT1 may be instrumental for the interactions among the three proteins. Based on this work and our previous study on TaHsp90, we speculate that the TaSGT1-TaHsp90.1 interaction is important for maintaining bread wheat seedling growth. The TaRAR1-TaSGT1-TaHsp90.2 and TaRAR1-TaSGT1-TaHsp90.3 interactions are involved in controlling the resistance to stripe rust disease. The new information obtained here should aid further functional investigations of TaRAR1-TaSGT1-TaHsp90 complexes in regulating bread wheat growth and disease resistance.

  19. Identification of heparin-binding EGF-like growth factor as a target in intercellular regulation of epidermal basal cell growth by suprabasal retinoic acid receptors.

    PubMed Central

    Xiao, J H; Feng, X; Di, W; Peng, Z H; Li, L A; Chambon, P; Voorhees, J J

    1999-01-01

    The role of retinoic acid receptors (RARs) in intercellular regulation of cell growth was assessed by targeting a dominant-negative RARalpha mutant (dnRARalpha) to differentiated suprabasal cells of mouse epidermis. dnRARalpha lacks transcriptional activation but not DNA-binding and receptor dimerization functions. Analysis of transgenic mice revealed that dnRARalpha dose-dependently impaired induction of basal cell proliferation and epidermal hyperplasia by all-trans RA (tRA). dnRARalpha formed heterodimers with endogenous retinoid X receptor-alpha (RXRalpha) over RA response elements in competition with remaining endogenous RARgamma-RXRalpha heterodimers, and dose-dependently impaired retinoid-dependent gene transcription. To identify genes regulated by retinoid receptors and involved in cell growth control, we analyzed the retinoid effects on expression of the epidermal growth factor (EGF) receptor, EGF, transforming growth factor-alpha, heparin-binding EGF-like growth factor (HB-EGF) and amphiregulin genes. In normal epidermis, tRA rapidly and selectively induced expression of HB-EGF but not the others. This induction occurred exclusively in suprabasal cells. In transgenic epidermis, dnRARalpha dose-dependently inhibited tRA induction of suprabasal HB-EGF and subsequent basal cell hyperproliferation. Together, our observations suggest that retinoid receptor heterodimers located in differentiated suprabasal cells mediate retinoid induction of HB-EGF, which in turn stimulates basal cell growth via intercellular signaling. These events may underlie retinoid action in epidermal regeneration during wound healing. PMID:10075925

  20. Retinoic acid signaling and mouse embryonic stem cell differentiation: Cross talk between genomic and non-genomic effects of RA.

    PubMed

    Rochette-Egly, Cécile

    2015-01-01

    Retinoic acid (RA), the active derivative of vitamin A, a fat-soluble vitamin, plays key roles in cell growth and differentiation by activating nuclear receptors, RARs (α, β and γ), which are ligand dependent regulators of transcription. The past years highlighted several novelties in the field that increased the complexity of RA effects. Indeed, in addition to its classical genomic effects, RA also has extranuclear and non-transcriptional effects. RA induces the rapid and transient activation of kinase cascades, which are integrated in the nucleus via the phosphorylation of RARs at a conserved serine residue located in the N-terminal domain and their coregulators. In order to investigate the relevance of RARs' phosphorylation in cell differentiation, mouse embryonic stem (mES) cells were used as a model. When treated with RA, these pluripotent cells give rise to neuronal cells. Cells invalidated for each RAR were generated as well as stable rescue lines expressing RARs mutated in phosphor acceptor sites. Such a strategy revealed that RA-induced neuronal differentiation involves the RARγ2 subtype and requires RARγ2 phosphorylation. Moreover, in gene expression profiling experiments, the phosphorylated form of RARγ2 was found to regulate a small subset of genes through binding a novel RA response element consisting of two direct repeats with a 7 base pair spacer. These new findings suggest an important role for RAR phosphorylation during cell differentiation, and pave the way for further investigations with other cell types and during embryonic development. This article is part of a Special Issue entitled Linking transcription to physiology in lipodomics. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Promoter methylation of APC and RAR-β genes as prognostic markers in non-small cell lung cancer (NSCLC).

    PubMed

    Feng, Hongxiang; Zhang, Zhenrong; Qing, Xin; Wang, Xiaowei; Liang, Chaoyang; Liu, Deruo

    2016-02-01

    Aberrant promoter hypermethylations of tumor suppressor genes are promising markers for lung cancer diagnosis and prognosis. The purpose of this study was to determine methylation status at APC and RAR-β promoters in primary NSCLC, and whether they have any relationship with survival. APC and RAR-β promoter methylation status were determined in 41 NSCLC patients using methylation specific PCR. APC promoter methylation was detectable in 9 (22.0%) tumor samples and 6 (14.6%) corresponding non-tumor samples (P=0.391). RAR-β promoter methylation was detectable in 13 (31.7%) tumor samples and 4 (9.8%) corresponding non-tumor samples (P=0.049) in the NSCLC patients. APC promoter methylation was found to be associated with T stage (P=0.046) and nodal status (P=0.019) in non-tumor samples, and with smoking (P=0.004) in tumor samples. RAR-β promoter methylation was found associated with age (P=0.031) in non-tumor samples and with primary tumor site in tumor samples. Patients with APC promoter methylation in tumor samples showed significantly longer survival than patients without it (Log-rank P=0.014). In a multivariate analysis of prognostic factors, APC methylation in tumor samples was an independent prognostic factor (P=0.012), as were N1 positive lymph node number (P=0.025) and N2 positive lymph node number (P=0.06). Our study shows that RAR-β methylation detected in lung tissue may be used as a predictive marker for NSCLC diagnosis and that APC methylation in tumor sample may be a useful marker for superior survival in NSCLC patients. Copyright © 2015. Published by Elsevier Inc.

  2. Nuclear receptors in bile acid metabolism

    PubMed Central

    Li, Tiangang; Chiang, John Y. L.

    2013-01-01

    Bile acids are signaling molecules that activate nuclear receptors, such as farnesoid X receptor, pregnane X receptor, constitutive androstane receptor, and vitamin D receptor, and play a critical role in the regulation of lipid, glucose, energy, and drug metabolism. These xenobiotic/endobiotic-sensing nuclear receptors regulate phase I oxidation, phase II conjugation, and phase III transport in bile acid and drug metabolism in the digestive system. Integration of bile acid metabolism with drug metabolism controls absorption, transport, and metabolism of nutrients and drugs to maintain metabolic homeostasis and also protects against liver injury, inflammation, and related metabolic diseases, such as nonalcoholic fatty liver disease, diabetes, and obesity. Bile-acid–based drugs targeting nuclear receptors are in clinical trials for treating cholestatic liver diseases and fatty liver disease. PMID:23330546

  3. Retinoic acid signaling pathways in development and diseases.

    PubMed

    Das, Bhaskar C; Thapa, Pritam; Karki, Radha; Das, Sasmita; Mahapatra, Sweta; Liu, Ting-Chun; Torregroza, Ingrid; Wallace, Darren P; Kambhampati, Suman; Van Veldhuizen, Peter; Verma, Amit; Ray, Swapan K; Evans, Todd

    2014-01-15

    Retinoids comprise a group of compounds each composed of three basic parts: a trimethylated cyclohexene ring that is a bulky hydrophobic group, a conjugated tetraene side chain that functions as a linker unit, and a polar carbon-oxygen functional group. Biochemical conversion of carotenoid or other retinoids to retinoic acid (RA) is essential for normal regulation of a wide range of biological processes including development, differentiation, proliferation, and apoptosis. Retinoids regulate various physiological outputs by binding to nuclear receptors called retinoic acid receptors (RARs) and retinoid X receptors (RXRs), which themselves are DNA-binding transcriptional regulators. The functional response of RA and their receptors are modulated by a host of coactivators and corepressors. Retinoids are essential in the development and function of several organ systems; however, deregulated retinoid signaling can contribute to serious diseases. Several natural and synthetic retinoids are in clinical use or undergoing trials for treating specific diseases including cancer. In this review, we provide a broad overview on the importance of retinoids in development and various diseases, highlighting various retinoids in the drug discovery process, ranging all the way from retinoid chemistry to clinical uses and imaging. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Structure of CC Chemokine Receptor 2 with Orthosteric and Allosteric Antagonists

    PubMed Central

    Zheng, Yi; Qin, Ling; Ortiz Zacarías, Natalia V.; de Vries, Henk; Han, Gye Won; Gustavsson, Martin; Dabros, Marta; Zhao, Chunxia; Cherney, Robert J.; Carter, Percy; Stamos, Dean; Abagyan, Ruben; Cherezov, Vadim; Stevens, Raymond C.; IJzerman, Adriaan P.; Heitman, Laura H.; Tebben, Andrew; Kufareva, Irina; Handel, Tracy M.

    2016-01-01

    Summary CC chemokine receptor 2 (CCR2) is one of 19 members of the chemokine receptor subfamily of human Class A G protein-coupled receptors (GPCRs). CCR2 is expressed on monocytes, immature dendritic cells and T cell subpopulations, and mediates their migration towards endogenous CC chemokine ligands such as CCL21. CCR2 and its ligands are implicated in numerous inflammatory and neurodegenerative diseases2 including atherosclerosis, multiple sclerosis, asthma, neuropathic pain, and diabetic nephropathy, as well as cancer3. These disease associations have motivated numerous preclinical studies and clinical trials4 (see ClinicalTrials.gov) in search of therapies that target the CCR2:chemokine axis. To aid drug discovery efforts5, we solved a structure of CCR2 in a ternary complex with an orthosteric (BMS-6816) and allosteric (CCR2-RA-[R]7) antagonist. BMS-681 inhibits chemokine binding by occupying the orthosteric pocket of the receptor in a previously unseen binding mode. CCR2-RA-[R] binds in a novel, highly druggable pocket that is the most intracellular allosteric site observed in Class A GPCRs to date; this site spatially overlaps the G protein-binding site in homologous receptors. CCR2-RA-[R] inhibits CCR2 non-competitively by blocking activation-associated conformational changes and formation of the G protein-binding interface. The conformational signature of the conserved microswitch residues observed in double-antagonist-bound CCR2 resembles the most inactive GPCR structures solved to date. Like other protein:protein interactions, receptor:chemokine complexes are considered challenging therapeutic targets for small molecules, and the present structure suggests diverse pocket epitopes that can be exploited to overcome drug design obstacles. PMID:27926736

  5. Retinoic acid signaling determines the fate of uterine stroma in the mouse Müllerian duct

    PubMed Central

    Nakajima, Tadaaki; Iguchi, Taisen; Sato, Tomomi

    2016-01-01

    The Müllerian duct develops into the oviduct, uterus, and vagina, all of which are quite distinct in their morphology and function. The epithelial fate of these female reproductive organs in developing mice is determined by factors secreted from the stroma; however, how stromal differentiation occurs in the female reproductive organs derived from the Müllerian duct is still unclear. In the present study, roles of retinoic acid (RA) signaling in developing female reproductive tracts were investigated. Retinol dehydrogenase 10 (RDH10) and aldehyde dehydrogenase family 1 subfamily A2 (ALDH1A2) mRNAs and proteins and transactivation activity of endogenous RA were found in the stroma of proximal Müllerian ducts and gradually decreased from the proximal to caudal regions in fetal mice. In organ-cultured Müllerian ducts, retinaldehyde or RA treatment induced uterine epithelial differentiation, defined as a layer of columnar epithelial cells negative for oviductal and vaginal epithelial markers. In contrast, inhibition of RA receptor (RAR) signaling induced vaginal epithelial differentiation, characterized as vaginal epithelial marker genes–positive stratified epithelium. Grafting experiments of the organ-cultured Müllerian duct revealed irreversible epithelial fate determination. Although RAR did not directly bind to the homeobox A10 (Hoxa10) promoter region, RA–RAR signaling stimulated Hoxa10 expression. Thus, RA–RAR signaling in the Müllerian duct determines the fate of stroma to form the future uterus and vagina. PMID:27911779

  6. Retinoic acid reduces chemotherapy-induced neuropathy in an animal model and patients with lung cancer

    PubMed Central

    Hernández-Pedro, N.; Fernández-González- Aragón, M.C.; Saavedra-Pérez, D.; Campos-Parra, A.D.; Ríos-Trejo, M.Á.; Cerón-Lizárraga, T.; Martínez-Barrera, L.; Pineda, B.; Ordóñez, G.; Ortiz-Plata, A.; Granados-Soto, V.; Sotelo, J.

    2011-01-01

    Objective: To evaluate the effect of all-trans retinoic acid (ATRA) as treatment for chemotherapy-induced peripheral neuropathy in an experimental animal model and in a randomized, double-blinded, controlled trial in patients with non-small-cell lung cancer (NSCLC). Methods: Forty male Wistar rats were randomized in 5 groups: group A, control; groups B and C, treated with cisplatin; and groups D and E, treated with paclitaxel. ATRA (20 mg/kg PO) was administered for 15 days in groups C and E. We evaluated neuropathy and nerve regeneration–related morphologic changes in sciatic nerve, the concentration of nerve growth factor (NGF), and retinoic acid receptor (RAR)–α and RAR-β expression. In addition, 95 patients with NSCLC under chemotherapy treatment were randomized to either ATRA (20 mg/m2/d) or placebo. Serum NGF, neurophysiologic tests, and clinical neurotoxicity were assessed. Results: The experimental animals developed neuropathy and axonal degeneration, associated with decreased NGF levels in peripheral nerves. Treatment with ATRA reversed sensorial changes and nerve morphology; this was associated with increased NGF levels and RAR-β expression. Patients treated with chemotherapy had clinical neuropathy and axonal loss assessed by neurophysiology, which was related to decreased NGF levels. ATRA reduced axonal degeneration demonstrated by nerve conduction velocity and clinical manifestations of neuropathy grades ≥2. Conclusions: ATRA reduced chemotherapy-induced experimental neuropathy, increased NGF levels, and induced RAR-β expression in nerve. In patients, reduction of NGF in serum was associated with the severity of neuropathy; ATRA treatment reduced the electrophysiologic alterations. Classification of evidence: This study provides Class II evidence that ATRA improves nerve conduction in patients with chemotherapy-induced peripheral neuropathy. Neurology® 2011;77:987–995 PMID:21865574

  7. Epigenetic alteration of p16 and retinoic acid receptor beta genes in the development of epithelial ovarian carcinoma.

    PubMed

    Bhagat, Rahul; Kumar, Sandeep Sriram; Vaderhobli, Shilpa; Premalata, Chennagiri S; Pallavi, Venkateshaiah Reddihalli; Ramesh, Gawari; Krishnamoorthy, Lakshmi

    2014-09-01

    Silencing of tumor suppressor and tumor-related genes by promoter hypermethylation is one of the major events in ovarian carcinogenesis. In this study, we analyzed aberrant promoter methylation of p16 and RAR-β genes in 134 epithelial ovarian carcinomas (EOCs), 23 low malignant potential (LMP) tumors, 26 benign cystadenomas, and 15 normal ovarian tissues. Methylation was investigated by methylation-specific PCR (MSP), and the results were confirmed by bisulfite DNA sequencing. Relative gene expression of p16 and RAR-β was done using quantitative reverse transcriptase PCR (qRT-PCR) on 51 EOC cases, 9 LMP tumors, and 7 benign cystadenomas with 5 normal ovarian tissues. Aberrant methylation for p16 and RAR-β was present in 43 % (58/134) and 31 % (41/134) in carcinoma cases, 22 % (05/23) and 52 % (12/23) in LMP tumors, and 42 % (11/26) and 69 % (18/26) in benign cystadenomas. No methylation was observed in any of the normal ovarian tissues. The mRNA expression level of p16 and RAR-β was significantly downregulated in EOC and LMP tumors than the corresponding normal tissues whereas the expression level was normal in benign cystadenomas for p16 and slightly reduced for RAR-β. A significant correlation of p16 promoter methylation was observed with reduced gene expression in EOC. For RAR-β, no significant correlation was observed between promoter methylation and gene expression. Our results suggest that epigenetic alterations of p16 and RAR-β have an important role in ovarian carcinogenesis and that mechanism along with methylation plays a significant role in downregulation of RAR-β gene in ovarian cancer.

  8. Plasmapheresis affects responses of slowly and rapidly adapting airway receptors to pulmonary venous congestion in dogs.

    PubMed Central

    Kappagoda, C T; Ravi, K

    1989-01-01

    1. The effects of plasmapheresis on the responses of rapidly adapting receptors (RARs) and slowly adapting receptors (SARs) of the airways to pulmonary venous congestion were examined in dogs anaesthetized with alpha-chloralose. Pulmonary venous congestion was produced in a graded manner by partial obstruction of the mitral valve sufficient to raise the mean left atrial pressure by 5, 10 and 15 mmHg. Plasmapheresis was performed by withdrawing 10% of blood volume twice. 2. Both RARs (n = 11) and SARs (n = 5) responded to pulmonary venous congestion by increasing their activities. The responses of the former were proportionately greater. 3. After plasmapheresis which reduced the concentration of plasma proteins by 12.3 +/- 1.0%, the responses of the RARs to pulmonary venous congestion were enhanced significantly. There was no significant change in the responses of SARs. 4. In another set of six RARs, the effects of graded pulmonary venous congestion were investigated twice with an interval of 45 min between the two observations. No significant differences were noted between the two responses. 5. Collection of lymph from the tracheobronchial lymph duct (n = 6) showed that after plasmapheresis, there was an increase in the control lymph flow. In addition, the lymph flow was enhanced during pulmonary venous congestion (mean left atrial pressure increased by 10 mmHg). 6. It is suggested that a natural stimulus for the excitation of the RAR is a function of the fluid fluxes in the pulmonary extravascular space. PMID:2607464

  9. Structure of CC chemokine receptor 2 with orthosteric and allosteric antagonists

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zheng, Yi; Qin, Ling; Zacarías, Natalia V. Ortiz

    CC chemokine receptor 2 (CCR2) is one of 19 members of the chemokine receptor subfamily of human class A G-protein-coupled receptors. CCR2 is expressed on monocytes, immature dendritic cells, and T-cell subpopulations, and mediates their migration towards endogenous CC chemokine ligands such as CCL2 (ref. 1). CCR2 and its ligands are implicated in numerous inflammatory and neurodegenerative diseases2 including atherosclerosis, multiple sclerosis, asthma, neuropathic pain, and diabetic nephropathy, as well as cancer3. These disease associations have motivated numerous preclinical studies and clinical trials4 (see http://www.clinicaltrials.gov) in search of therapies that target the CCR2–chemokine axis. To aid drug discovery efforts5, heremore » we solve a structure of CCR2 in a ternary complex with an orthosteric (BMS-681 (ref. 6)) and allosteric (CCR2-RA-[R]7) antagonist. BMS-681 inhibits chemokine binding by occupying the orthosteric pocket of the receptor in a previously unseen binding mode. CCR2-RA-[R] binds in a novel, highly druggable pocket that is the most intracellular allosteric site observed in class A G-protein-coupled receptors so far; this site spatially overlaps the G-protein-binding site in homologous receptors. CCR2-RA-[R] inhibits CCR2 non-competitively by blocking activation-associated conformational changes and formation of the G-protein-binding interface. The conformational signature of the conserved microswitch residues observed in double-antagonist-bound CCR2 resembles the most inactive G-protein-coupled receptor structures solved so far. Like other protein–protein interactions, receptor–chemokine complexes are considered challenging therapeutic targets for small molecules, and the present structure suggests diverse pocket epitopes that can be exploited to overcome obstacles in drug design.« less

  10. Fatty acids activate a chimera of the clofibric acid-activated receptor and the glucocorticoid receptor.

    PubMed Central

    Göttlicher, M; Widmark, E; Li, Q; Gustafsson, J A

    1992-01-01

    Peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643 have been shown to activate PPAR (peroxisome proliferator-activated receptor), a member of the steroid nuclear receptor superfamily. We have cloned the cDNA from the rat that is homologous to that from the mouse [Issemann, I. & Green, S. (1990) Nature (London) 347, 645-650], which encodes a 97% similar protein with a particularly well-conserved putative ligand-binding domain. To search for physiologically occurring activators, we established a transcriptional transactivation assay by stably expressing in CHO cells a chimera of rat PPAR and the human glucocorticoid receptor that activates expression of the placental alkaline phosphatase reporter gene under the control of the mouse mammary tumor virus promoter. Testing of compounds related to lipid metabolism or peroxisomal proliferation revealed that 150 microM concentrations of arachidonic or linoleic acid but not of dehydroepiandrosterone, cholesterol, or 25-hydroxy-cholesterol, activate the receptor chimera. In addition, saturated fatty acids induce the reporter gene. Shortening the chain length to n = 6 or introduction of an omega-terminal carboxylic group abolished the activation potential of the fatty acid. In conclusion, the present results indicate that fatty acids can regulate gene expression mediated by a member of the steroid nuclear receptor superfamily. Images PMID:1316614

  11. High-Mobility Group Chromatin Proteins 1 and 2 Functionally Interact with Steroid Hormone Receptors To Enhance Their DNA Binding In Vitro and Transcriptional Activity in Mammalian Cells

    PubMed Central

    Boonyaratanakornkit, Viroj; Melvin, Vida; Prendergast, Paul; Altmann, Magda; Ronfani, Lorenza; Bianchi, Marco E.; Taraseviciene, Laima; Nordeen, Steven K.; Allegretto, Elizabeth A.; Edwards, Dean P.

    1998-01-01

    We previously reported that the chromatin high-mobility group protein 1 (HMG-1) enhances the sequence-specific DNA binding activity of progesterone receptor (PR) in vitro, thus providing the first evidence that HMG-1 may have a coregulatory role in steroid receptor-mediated gene transcription. Here we show that HMG-1 and the highly related HMG-2 stimulate DNA binding by other steroid receptors, including estrogen, androgen, and glucocorticoid receptors, but have no effect on DNA binding by several nonsteroid nuclear receptors, including retinoid acid receptor (RAR), retinoic X receptor (RXR), and vitamin D receptor (VDR). As highly purified recombinant full-length proteins, all steroid receptors tested exhibited weak binding affinity for their optimal palindromic hormone response elements (HREs), and the addition of purified HMG-1 or -2 substantially increased their affinity for HREs. Purified RAR, RXR, and VDR also exhibited little to no detectable binding to their cognate direct repeat HREs but, in contrast to results with steroid receptors, the addition of HMG-1 or HMG-2 had no stimulatory effect. Instead, the addition of purified RXR enhanced RAR and VDR DNA binding through a heterodimerization mechanism and HMG-1 or HMG-2 had no further effect on DNA binding by RXR-RAR or RXR-VDR heterodimers. HMG-1 and HMG-2 (HMG-1/-2) themselves do not bind to progesterone response elements, but in the presence of PR they were detected as part of an HMG-PR-DNA ternary complex. HMG-1/-2 can also interact transiently in vitro with PR in the absence of DNA; however, no direct protein interaction was detected with VDR. These results, taken together with the fact that PR can bend its target DNA and that HMG-1/-2 are non-sequence-specific DNA binding proteins that recognize DNA structure, suggest that HMG-1/-2 are recruited to the PR-DNA complex by the combined effect of transient protein interaction and DNA bending. In transient-transfection assays, coexpression of HMG-1 or HMG-2

  12. MiRAR-miRNA Activity Reporter for Living Cells.

    PubMed

    Turk, Matthew A; Chung, Christina Z; Manni, Emad; Zukowski, Stephanie A; Engineer, Anish; Badakhshi, Yasaman; Bi, Yumin; Heinemann, Ilka U

    2018-06-19

    microRNA (miRNA) activity and regulation are of increasing interest as new therapeutic targets. Traditional approaches to assess miRNA levels in cells rely on RNA sequencing or quantitative PCR. While useful, these approaches are based on RNA extraction and cannot be applied in real-time to observe miRNA activity with single-cell resolution. We developed a green fluorescence protein (GFP)-based reporter system that allows for a direct, real-time readout of changes in miRNA activity in live cells. The miRNA activity reporter (MiRAR) consists of GFP fused to a 3′ untranslated region containing specific miRNA binding sites, resulting in miRNA activity-dependent GFP expression. Using qPCR, we verified the inverse relationship of GFP fluorescence and miRNA levels. We demonstrated that this novel optogenetic reporter system quantifies cellular levels of the tumor suppressor miRNA let-7 in real-time in single Human embryonic kidney 293 (HEK 293) cells. Our data shows that the MiRAR can be applied to detect changes in miRNA levels upon disruption of miRNA degradation pathways. We further show that the reporter could be adapted to monitor another disease-relevant miRNA, miR-122. With trivial modifications, this approach could be applied across the miRNome for quantification of many specific miRNA in cell cultures, tissues, or transgenic animal models.

  13. Control of Innate and Adaptive Lymphocytes by the RAR-Retinoic Acid Axis.

    PubMed

    Kim, Chang H

    2018-02-01

    Lymphocytes, such as T cells, B cells, and innate lymphoid cells (ILCs), play central roles in regulating immune responses. Retinoic acids (RAs) are vitamin A metabolites, produced and metabolized by certain tissue cells and myeloid cells in a tissue-specific manner. It has been established that RAs induce gut-homing receptors on T cells, B cells, and ILCs. A mounting body of evidence indicates that RAs exert far-reaching effects on functional differentiation and fate of these lymphocytes. For example, RAs promote effector T cell maintenance, generation of induced gut-homing regulatory and effector T cell subsets, antibody production by B cells, and functional maturation of ILCs. Key functions of RAs in regulating major groups of innate and adaptive lymphocytes are highlighted in this article.

  14. High Concentrations of Tranexamic Acid Inhibit Ionotropic Glutamate Receptors.

    PubMed

    Lecker, Irene; Wang, Dian-Shi; Kaneshwaran, Kirusanthy; Mazer, C David; Orser, Beverley A

    2017-07-01

    The antifibrinolytic drug tranexamic acid is structurally similar to the amino acid glycine and may cause seizures and myoclonus by acting as a competitive antagonist of glycine receptors. Glycine is an obligatory co-agonist of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. Thus, it is plausible that tranexamic acid inhibits NMDA receptors by acting as a competitive antagonist at the glycine binding site. The aim of this study was to determine whether tranexamic acid inhibits NMDA receptors, as well as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate subtypes of ionotropic glutamate receptors. Tranexamic acid modulation of NMDA, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainate receptors was studied using whole cell voltage-clamp recordings of current from cultured mouse hippocampal neurons. Tranexamic acid rapidly and reversibly inhibited NMDA receptors (half maximal inhibitory concentration = 241 ± 45 mM, mean ± SD; 95% CI, 200 to 281; n = 5) and shifted the glycine concentration-response curve for NMDA-evoked current to the right. Tranexamic acid also inhibited α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (half maximal inhibitory concentration = 231 ± 91 mM; 95% CI, 148 to 314; n = 5 to 6) and kainate receptors (half maximal inhibitory concentration = 90 ± 24 mM; 95% CI, 68 to 112; n = 5). Tranexamic acid inhibits NMDA receptors likely by reducing the binding of the co-agonist glycine and also inhibits α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate receptors. Receptor blockade occurs at high millimolar concentrations of tranexamic acid, similar to the concentrations that occur after topical application to peripheral tissues. Glutamate receptors in tissues including bone, heart, and nerves play various physiologic roles, and tranexamic acid inhibition of these receptors may contribute to adverse drug effects.

  15. Effect of chronic mitral valve damage on activity of pulmonary rapidly adapting receptors in the rabbit

    PubMed Central

    Gunawardena, S; Bravo, E; Kappagoda, C T

    1998-01-01

    The effects of acute pulmonary venous congestion on the activity of rapidly adapting receptors (RARs) were determined in intact (control and sham-operated) rabbits and in rabbits 6 and 12 weeks after surgical destruction of the mitral valve.Destruction of the mitral valve increased the mean left atrial pressure (LAP) by approximately 2·6 and 3·8 mmHg, 6 and 12 weeks after surgery, respectively. These changes were accompanied by significant increases in left ventricular weight. The effect of acute increments in LAP on RAR activity was examined against this background of chronic pulmonary venous congestion.In intact control and sham-operated animals RAR activity increased from 48·8 ± 0·9 to 83·5 ± 3·6 and 121·1 ± 4·7 action potentials min−1 when the LAP was raised by 5 and 10 mmHg, respectively, above control values. Six weeks after surgery only 40 % of RARs were activated in this way.In animals maintained for 12 weeks after surgery, RAR activity at LAPs of 6·6 ± 1·2 (control), 11·6 ± 1·2 and 16·6 ± 1·2 (mmHg) were 35·5 ± 2·3, 33·8 ± 14·4 and 34·0 ± 3·4 action potentials min−1, respectively. These changes were statistically not significant.Slowly adapting receptors (SARs) in the lung showed a small but statistically significant increase in activity when the left atrial pressure was acutely elevated in both intact and mitral valve damaged animals.It is concluded that chronic pulmonary venous congestion resulting from destruction of the mitral valve attenuates the ability of RARs to respond to acute moderate elevations of LAP. PMID:9679165

  16. Hemorrhoidal artery ligation (HAL) and rectoanal repair (RAR): retrospective analysis of 408 patients in a single center.

    PubMed

    Scheyer, M; Antonietti, E; Rollinger, G; Lancee, S; Pokorny, H

    2015-01-01

    Rectoanal repair (RAR), which combines doppler-guided hemorrhoidal artery ligation (HAL) and mucopexy via lifting of the hemorrhoidal prolapse, offers a minimally invasive alternative to conventional hemorrhoidectomy. Patients with grade II hemorrhoids were treated with HAL, and patients with grade III and IV hemorrhoids were treated with the RAR procedure by two surgeons. Postoperative follow-up was performed clinically and by proctoscopy after 8 weeks routinely, and long-term follow-up was performed using a standardized postal questionnaire. The overall complication rate was 29% (n = 118). After short-term follow-up, 26% (n = 106) of patients reported recurrent or persistent prolapsing piles, while 21% (n = 86) of patients had recurrent bleeding. After long-term follow-up, 24% (n = 98) of patients reported prolapsing piles, 3% (n = 12) bleeding, 3% (n = 12) pruritus, and 2% (n = 8) anal pain, while 20% (n = 82) complained of persistent mixed symptoms. HAL and RAR provide prolonged relief for patients with hemorrhoidal disease whose main symptoms are bleeding, pruritus and pain but not for patients with prolapse as an initial indication.

  17. Differentiated all-trans retinoic acid response of naive CD4+CD25– cells isolated from rats with collagen-induced arthritis and healthy ones under in vitro conditions

    PubMed Central

    Żyromska, Edyta; Piasecki, Tomasz; Rossowska, Joanna; Kędzierska, Anna; Nowak, Marcin; Żyromski, Marcin; Chełmońska-Soyta, Anna

    2017-01-01

    Aim o the study To compare the potential of CD4+CD25– cells, isolated from both healthy rats and rats with CIA (Collagen-Induced Arthritis), for differentiation into regulatory T cells in the presence of all-trans retinoic acid in order to learn more about the activation mechanisms and therapeutic potential of regulatory T cells. Material and methods Sorted CD4+CD25– cells were cultured in vitro with/without ATRA, and then the frequency of regulatory T cells and their ability to secrete IL-10 by CD4+ FOXP3+ cells was examined. Gene expression of the foxp3, rarα, rarβ, rxrβ, and ppar β/δ and protein expression of the Rarα, Rarβ, and Rxrβ in cells after stimulation with ATRA were also investigated. Results CD4+CD25– cells isolated from healthy animals or from animals with CIA are characterised by different potential of the differentiation into CD4+CD25+ FOXP3+ cells. Retinoic acid receptor Rxrβ is present in the CD4+CD25– cells isolated from rats with CIA. Conclusions We showed that although ATRA did not increase the frequency of Treg in culture, it significantly increased expression of rarβ and rxrβ only in lymphocytes taken from diseased animals and foxp3 expression only in healthy animals. Moreover, after ATRA stimulation, the frequency of Treg-produced IL-10 tended to be lower in diseased animals than in the healthy group. The results imply that the potential of naïve cell CD4 lymphocytes to differentiate into Tregs and their putative suppressive function is dependent on the donor’s health status. PMID:28680330

  18. 13-cis Retinoic acid induces apoptosis and cell cycle arrest in human SEB-1 sebocytes.

    PubMed

    Nelson, Amanda M; Gilliland, Kathryn L; Cong, Zhaoyuan; Thiboutot, Diane M

    2006-10-01

    Isotretinoin (13-cis retinoic acid (13-cis RA)) is the most potent inhibitor of sebum production, a key component in the pathophysiology of acne, yet its mechanism of action remains largely unknown. The effects of 13-cis RA, 9-cis retinoic acid (9-cis RA), and all-trans retinoic acid (ATRA) on cell proliferation, apoptosis, and cell cycle proteins were examined in SEB-1 sebocytes and keratinocytes. 13-cis RA causes significant dose-dependent and time-dependent decreases in viable SEB-1 sebocytes. A portion of this decrease can be attributed to cell cycle arrest as evidenced by decreased DNA synthesis, increased p21 protein expression, and decreased cyclin D1. Although not previously demonstrated in sebocytes, we report that 13-cis RA induces apoptosis in SEB-1 sebocytes as shown by increased Annexin V-FITC staining, increased TUNEL staining, and increased cleaved caspase 3 protein. Furthermore, the ability of 13-cis RA to induce apoptosis cannot be recapitulated by 9-cis RA or ATRA, and it is not inhibited by the presence of a retinoid acid receptor (RAR) pan-antagonist AGN 193109. Taken together these data indicate that 13-cis RA causes cell cycle arrest and induces apoptosis in SEB-1 sebocytes by a RAR-independent mechanism, which contributes to its sebosuppressive effect and the resolution of acne.

  19. Spectrum of mutations in RARS-T patients includes TET2 and ASXL1 mutations.

    PubMed

    Szpurka, Hadrian; Jankowska, Anna M; Makishima, Hideki; Bodo, Juraj; Bejanyan, Nelli; Hsi, Eric D; Sekeres, Mikkael A; Maciejewski, Jaroslaw P

    2010-08-01

    While a majority of patients with refractory anemia with ring sideroblasts and thrombocytosis harbor JAK2V617F and rarely MPLW515L, JAK2/MPL-negative cases constitute a diagnostic problem. 23 RARS-T cases were investigated applying immunohistochemical phospho-STAT5, sequencing and SNP-A-based karyotyping. Based on the association of TET2/ASXL1 mutations with MDS/MPN we studied molecular pattern of these genes. Two patients harbored ASXL1 and another 2 TET2 mutations. Phospho-STAT5 activation was present in one mutated TET2 and ASXL1 case. JAK2V617F/MPLW515L mutations were absent in TET2/ASXL1 mutants, indicating that similar clinical phenotype can be produced by various MPN-associated mutations and that additional unifying lesions may be present in RARS-T. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  20. Retinoic Acid Is Involved in the Metamorphosis of the Anal Fin into an Intromittent Organ, the Gonopodium, in the Green Swordtail (Xiphophorus hellerii)

    PubMed Central

    Meyer, Axel; Begemann, Gerrit

    2013-01-01

    In poeciliid fish the male anal fin has been transformed into a gonopodium, an intromittent organ required for internal fertilization. Elevated testosterone levels induce metamorphosis of a subset of anal fin rays to grow and form the specialized terminal structures of the gonopodium. The molecular mechanisms underlying these processes are largely unknown. Here, we investigated whether retinoic acid (RA) signaling is involved in gonopodium development in the swordtail Xiphophorus hellerii. We showed that aldh1a2, a RA synthesizing enzyme, and the RA receptors, rar-ga and rar-gb, are expressed in anal fins during metamorphosis. aldh1a2 expression is regulated by testosterone in a concentration-dependent manner and is up-regulated in both hormone-induced and naturally developing gonopodia. Androgen receptor (ar), a putative regulator of gonopodial development, is co-expressed with aldh1a2 and the RA receptors in gonopodial rays. Importantly, experimental increase of RA signaling promoted growth of the gonopodium and increased the number of new segments. Based on gene expression analyses and pharmacological manipulation of gonopodium development, we show that the RA signaling pathway is activated in response to androgen signaling and promotes fin ray growth and development during the metamorphosis of the anal fin into the gonopodium. PMID:24204880

  1. Neuropathologic Characterization of Pontocerebellar Hypoplasia Type 6 Associated With Cardiomyopathy and Hydrops Fetalis and Severe Multisystem Respiratory Chain Deficiency due to Novel RARS2 Mutations.

    PubMed

    Lax, Nichola Z; Alston, Charlotte L; Schon, Katherine; Park, Soo-Mi; Krishnakumar, Deepa; He, Langping; Falkous, Gavin; Ogilvy-Stuart, Amanda; Lees, Christoph; King, Rosalind H; Hargreaves, Iain P; Brown, Garry K; McFarland, Robert; Dean, Andrew F; Taylor, Robert W

    2015-07-01

    Autosomal recessive mutations in the RARS2 gene encoding the mitochondrial arginyl-transfer RNA synthetase cause infantile-onset myoencephalopathy pontocerebellar hypoplasia type 6 (PCH6). We describe 2 sisters with novel compound heterozygous RARS2 mutations who presented perinatally with neurologic features typical of PCH6 but with additional features including cardiomyopathy, hydrops, and pulmonary hypoplasia and who died at 1 day and 14 days of age. Magnetic resonance imaging findings included marked cerebellar hypoplasia, gyral immaturity, punctate lesions in cerebral white matter, and unfused deep cerebral grey matter. Enzyme histochemistry of postmortem tissues revealed a near-global cytochrome c oxidase-deficiency; assessment of respiratory chain enzyme activities confirmed severe deficiencies involving complexes I, III, and IV. Molecular genetic studies revealed 2 RARS2 gene mutations: a c.1A>G, p.? variant predicted to abolish the initiator methionine, and a deep intronic c.613-3927C>T variant causing skipping of exons 6-8 in the mature RARS2 transcript. Neuropathologic investigation included low brain weights, small brainstem and cerebellum, deep cerebral white matter pathology, pontine nucleus neuron loss (in 1 sibling), and peripheral nerve pathology. Mitochondrial respiratory chain immunohistochemistry in brain tissues confirmed an absence of complexes I and IV immunoreactivity with sparing of mitochondrial numbers. These cases expand the clinical spectrum of RARS2 mutations, including antenatal features and widespread mitochondrial respiratory chain deficiencies in postmortem brain tissues.

  2. Hyodeoxycholic acid derivatives as liver X receptor α and G-protein-coupled bile acid receptor agonists

    NASA Astrophysics Data System (ADS)

    de Marino, Simona; Carino, Adriana; Masullo, Dario; Finamore, Claudia; Marchianò, Silvia; Cipriani, Sabrina; di Leva, Francesco Saverio; Catalanotti, Bruno; Novellino, Ettore; Limongelli, Vittorio; Fiorucci, Stefano; Zampella, Angela

    2017-02-01

    Bile acids are extensively investigated for their potential in the treatment of human disorders. The liver X receptors (LXRs), activated by oxysterols and by a secondary bile acid named hyodeoxycholic acid (HDCA), have been found essential in the regulation of lipid homeostasis in mammals. Unfortunately, LXRα activates lipogenic enzymes causing accumulation of lipid in the liver. In addition to LXRs, HDCA has been also shown to function as ligand for GPBAR1, a G protein coupled receptor for secondary bile acids whose activation represents a promising approach to liver steatosis. In the present study, we report a library of HDCA derivatives endowed with modulatory activity on the two receptors. The lead optimization of HDCA moiety was rationally driven by the structural information on the binding site of the two targets and results from pharmacological characterization allowed the identification of hyodeoxycholane derivatives with selective agonistic activity toward LXRα and GPBAR1 and notably to the identification of the first example of potent dual LXRα/GPBAR1 agonists. The new chemical entities might hold utility in the treatment of dyslipidemic disorders.

  3. Is retinoic acid genetic machinery a chordate innovation?

    PubMed

    Cañestro, Cristian; Postlethwait, John H; Gonzàlez-Duarte, Roser; Albalat, Ricard

    2006-01-01

    Development of many chordate features depends on retinoic acid (RA). Because the action of RA during development seems to be restricted to chordates, it had been previously proposed that the "invention" of RA genetic machinery, including RA-binding nuclear hormone receptors (Rars), and the RA-synthesizing and RA-degrading enzymes Aldh1a (Raldh) and Cyp26, respectively, was an important step for the origin of developmental mechanisms leading to the chordate body plan. We tested this hypothesis by conducting an exhaustive survey of the RA machinery in genomic databases for twelve deuterostomes. We reconstructed the evolution of these genes in deuterostomes and showed for the first time that RA genetic machinery--that is Aldh1a, Cyp26, and Rar orthologs--is present in nonchordate deuterostomes. This finding implies that RA genetic machinery was already present during early deuterostome evolution, and therefore, is not a chordate innovation. This new evolutionary viewpoint argues against the hypothesis that the acquisition of gene families underlying RA metabolism and signaling was a key event for the origin of chordates. We propose a new hypothesis in which lineage-specific duplication and loss of RA machinery genes could be related to the morphological radiation of deuterostomes.

  4. Retinoic acid signaling is dispensable for somatic development and function in the mammalian ovary.

    PubMed

    Minkina, Anna; Lindeman, Robin E; Gearhart, Micah D; Chassot, Anne-Amandine; Chaboissier, Marie-Christine; Ghyselinck, Norbert B; Bardwell, Vivian J; Zarkower, David

    2017-04-15

    Retinoic acid (RA) is a potent inducer of cell differentiation and plays an essential role in sex-specific germ cell development in the mammalian gonad. RA is essential for male gametogenesis and hence fertility. However, RA can also disrupt sexual cell fate in somatic cells of the testis, promoting transdifferentiation of male Sertoli cells to female granulosa-like cells when the male sexual regulator Dmrt1 is absent. The feminizing ability of RA in the Dmrt1 mutant somatic testis suggests that RA might normally play a role in somatic cell differentiation or cell fate maintenance in the ovary. To test for this possibility we disrupted RA signaling in somatic cells of the early fetal ovary using three genetic strategies and one pharmaceutical approach. We found that deleting all three RA receptors (RARs) in the XX somatic gonad at the time of sex determination did not significantly affect ovarian differentiation, follicle development, or female fertility. Transcriptome analysis of adult triple mutant ovaries revealed remarkably little effect on gene expression in the absence of somatic RAR function. Likewise, deletion of three RA synthesis enzymes (Aldh1a1-3) at the time of sex determination did not masculinize the ovary. A dominant-negative RAR transgene altered granulosa cell proliferation, likely due to interference with a non-RA signaling pathway, but did not prevent granulosa cell specification and oogenesis or abolish fertility. Finally, culture of fetal XX gonads with an RAR antagonist blocked germ cell meiotic initiation but did not disrupt sex-biased gene expression. We conclude that RA signaling, although crucial in the ovary for meiotic initiation, is not required for granulosa cell specification, differentiation, or reproductive function. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. A rare single cytogenetic finding of isochromosome 14q in a female with refractory anemia with ring sideroblasts (RARS)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Haag, M.M.; Sutcliffe, M.J.; Nelson, R.P.

    1994-09-01

    Clonal cytogenetic abnormalities occur in 79% of patients with myelodysplastic syndrome (MDS) and can be used to diagnose malignancy. Some of these clonal chromosomal changes have been useful in evaluation of the pathobiological similarity between MDS and acute nonlymphocytic leukemia (ANLL) and can be used to monitor the disease progression. A 44-year-old woman, presenting with normochromic, normocytic anemia was clinically asymptomatic and physical examination revealed no lymphadenopathy or hepatosplenomegaly. Stains for iron demonstrated adequate stores but with numerours ring sideroblasts which constituted approximately 15% of the total erythoblastic population. No increased reticulum or fibrosis was noted. These findings supported amore » diagnosis of MDS, classification refractory anemia with ring sideroblasts (RARS). Bone marrow cytogentic analysis showed an isochromosome 14q as the sole chromosome abnormality and this was confirmed by molecular cytogenetics using a whole chromosome Coatasome probe for No. 14. A population of 46,XX cells (20%) was also observed. Numerous interphase cells had three isolated fluorescent signals for No. 14. Structural and numerical abnormalities of chromosome No. 14 are reported in many hematological disorders, but few structural abnormalities have been reported for RARS and no extra copies, including i(14q), have been reported for MD or RARS. However, examples of extra copies of No. 14, including the isochromosome form, have been reported for ANLL. Since 15% of RARS patients progress to ANLL, there may be prognostic significance to this chromosome abnormality for his patient. The patient is awaiting a suitable donor for bone marrow transplantation. The presence of isochromosome No. 14 in the malignant cells offers an opportunity to monitor disease progression pre-transplantation and minimal residual disease post-transplantation.« less

  6. Allergen-Induced Dermatitis Causes Alterations in Cutaneous Retinoid-Mediated Signaling in Mice

    PubMed Central

    Gericke, Janine; Ittensohn, Jan; Mihály, Johanna; Dubrac, Sandrine; Rühl, Ralph

    2013-01-01

    Nuclear receptor-mediated signaling via RARs and PPARδ is involved in the regulation of skin homeostasis. Moreover, activation of both RAR and PPARδ was shown to alter skin inflammation. Endogenous all-trans retinoic acid (ATRA) can activate both receptors depending on specific transport proteins: Fabp5 initiates PPARδ signaling whereas Crabp2 promotes RAR signaling. Repetitive topical applications of ovalbumin (OVA) in combination with intraperitoneal injections of OVA or only intraperitoneal OVA applications were used to induce allergic dermatitis. In our mouse model, expression of IL-4, and Hbegf increased whereas expression of involucrin, Abca12 and Spink5 decreased in inflamed skin, demonstrating altered immune response and epidermal barrier homeostasis. Comprehensive gene expression analysis showed alterations of the cutaneous retinoid metabolism and retinoid-mediated signaling in allergic skin immune response. Notably, ATRA synthesis was increased as indicated by the elevated expression of retinaldehyde dehydrogenases and increased levels of ATRA. Consequently, the expression pattern of genes downstream to RAR was altered. Furthermore, the increased ratio of Fabp5 vs. Crabp2 may indicate an up-regulation of the PPARδ pathway in allergen-induced dermatitis in addition to the altered RAR signaling. Thus, our findings suggest that ATRA levels, RAR-mediated signaling and signaling involved in PPARδ pathways are mainly increased in allergen-induced dermatitis and may contribute to the development and/or maintenance of allergic skin diseases. PMID:23977003

  7. Allergen-induced dermatitis causes alterations in cutaneous retinoid-mediated signaling in mice.

    PubMed

    Gericke, Janine; Ittensohn, Jan; Mihály, Johanna; Dubrac, Sandrine; Rühl, Ralph

    2013-01-01

    Nuclear receptor-mediated signaling via RARs and PPARδ is involved in the regulation of skin homeostasis. Moreover, activation of both RAR and PPARδ was shown to alter skin inflammation. Endogenous all-trans retinoic acid (ATRA) can activate both receptors depending on specific transport proteins: Fabp5 initiates PPARδ signaling whereas Crabp2 promotes RAR signaling. Repetitive topical applications of ovalbumin (OVA) in combination with intraperitoneal injections of OVA or only intraperitoneal OVA applications were used to induce allergic dermatitis. In our mouse model, expression of IL-4, and Hbegf increased whereas expression of involucrin, Abca12 and Spink5 decreased in inflamed skin, demonstrating altered immune response and epidermal barrier homeostasis. Comprehensive gene expression analysis showed alterations of the cutaneous retinoid metabolism and retinoid-mediated signaling in allergic skin immune response. Notably, ATRA synthesis was increased as indicated by the elevated expression of retinaldehyde dehydrogenases and increased levels of ATRA. Consequently, the expression pattern of genes downstream to RAR was altered. Furthermore, the increased ratio of Fabp5 vs. Crabp2 may indicate an up-regulation of the PPARδ pathway in allergen-induced dermatitis in addition to the altered RAR signaling. Thus, our findings suggest that ATRA levels, RAR-mediated signaling and signaling involved in PPARδ pathways are mainly increased in allergen-induced dermatitis and may contribute to the development and/or maintenance of allergic skin diseases.

  8. Neuropathologic Characterization of Pontocerebellar Hypoplasia Type 6 Associated With Cardiomyopathy and Hydrops Fetalis and Severe Multisystem Respiratory Chain Deficiency due to Novel RARS2 Mutations

    PubMed Central

    Lax, Nichola Z.; Alston, Charlotte L.; Schon, Katherine; Park, Soo-Mi; Krishnakumar, Deepa; He, Langping; Falkous, Gavin; Ogilvy-Stuart, Amanda; Lees, Christoph; King, Rosalind H.; Hargreaves, Iain P.; Brown, Garry K.; McFarland, Robert; Dean, Andrew F.; Taylor, Robert W.

    2015-01-01

    Abstract Autosomal recessive mutations in the RARS2 gene encoding the mitochondrial arginyl-transfer RNA synthetase cause infantile-onset myoencephalopathy pontocerebellar hypoplasia type 6 (PCH6). We describe 2 sisters with novel compound heterozygous RARS2 mutations who presented perinatally with neurologic features typical of PCH6 but with additional features including cardiomyopathy, hydrops, and pulmonary hypoplasia and who died at 1 day and 14 days of age. Magnetic resonance imaging findings included marked cerebellar hypoplasia, gyral immaturity, punctate lesions in cerebral white matter, and unfused deep cerebral grey matter. Enzyme histochemistry of postmortem tissues revealed a near-global cytochrome c oxidase-deficiency; assessment of respiratory chain enzyme activities confirmed severe deficiencies involving complexes I, III, and IV. Molecular genetic studies revealed 2 RARS2 gene mutations: a c.1A>G, p.? variant predicted to abolish the initiator methionine, and a deep intronic c.613-3927C>T variant causing skipping of exons 6–8 in the mature RARS2 transcript. Neuropathologic investigation included low brain weights, small brainstem and cerebellum, deep cerebral white matter pathology, pontine nucleus neuron loss (in 1 sibling), and peripheral nerve pathology. Mitochondrial respiratory chain immunohistochemistry in brain tissues confirmed an absence of complexes I and IV immunoreactivity with sparing of mitochondrial numbers. These cases expand the clinical spectrum of RARS2 mutations, including antenatal features and widespread mitochondrial respiratory chain deficiencies in postmortem brain tissues. PMID:26083569

  9. Free fatty acid (FFA) and hydroxy carboxylic acid (HCA) receptors.

    PubMed

    Offermanns, Stefan

    2014-01-01

    Saturated and unsaturated free fatty acids (FFAs), as well as hydroxy carboxylic acids (HCAs) such as lactate and ketone bodies, are carriers of metabolic energy, precursors of biological mediators, and components of biological structures. However, they are also able to exert cellular effects through G protein-coupled receptors named FFA1-FFA4 and HCA1-HCA3. Work during the past decade has shown that these receptors are widely expressed in the human body and regulate the metabolic, endocrine, immune and other systems to maintain homeostasis under changing dietary conditions. The development of genetic mouse models and the generation of synthetic ligands of individual FFA and HCA receptors have been instrumental in identifying cellular and biological functions of these receptors. These studies have produced strong evidence that several FFA and HCA receptors can be targets for the prevention and treatment of various diseases, including type 2 diabetes mellitus, obesity, and inflammation.

  10. Retinoid Receptors in Bone and Their Role in Bone Remodeling

    PubMed Central

    Henning, Petra; Conaway, H. Herschel; Lerner, Ulf H.

    2015-01-01

    Vitamin A (retinol) is a necessary and important constituent of the body which is provided by food intake of retinyl esters and carotenoids. Vitamin A is known best for being important for vision, but in addition to the eye, vitamin A is necessary in numerous other organs in the body, including the skeleton. Vitamin A is converted to an active compound, all-trans-retinoic acid (ATRA), which is responsible for most of its biological actions. ATRA binds to intracellular nuclear receptors called retinoic acid receptors (RARα, RARβ, RARγ). RARs and closely related retinoid X receptors (RXRα, RXRβ, RXRγ) form heterodimers which bind to DNA and function as ligand-activated transcription factors. It has been known for many years that hypervitaminosis A promotes skeleton fragility by increasing osteoclast formation and decreasing cortical bone mass. Some epidemiological studies have suggested that increased intake of vitamin A and increased serum levels of retinoids may decrease bone mineral density and increase fracture rate, but the literature on this is not conclusive. The current review summarizes how vitamin A is taken up by the intestine, metabolized, stored in the liver, and processed to ATRA. ATRA’s effects on formation and activity of osteoclasts and osteoblasts are outlined, and a summary of clinical data pertaining to vitamin A and bone is presented. PMID:25814978

  11. Amino acid sequence of the human fibronectin receptor

    PubMed Central

    1987-01-01

    The amino acid sequence deduced from cDNA of the human placental fibronectin receptor is reported. The receptor is composed of two subunits: an alpha subunit of 1,008 amino acids which is processed into two polypeptides disulfide bonded to one another, and a beta subunit of 778 amino acids. Each subunit has near its COOH terminus a hydrophobic segment. This and other sequence features suggest a structure for the receptor in which the hydrophobic segments serve as transmembrane domains anchoring each subunit to the membrane and dividing each into a large ectodomain and a short cytoplasmic domain. The alpha subunit ectodomain has five sequence elements homologous to consensus Ca2+- binding sites of several calcium-binding proteins, and the beta subunit contains a fourfold repeat strikingly rich in cysteine. The alpha subunit sequence is 46% homologous to the alpha subunit of the vitronectin receptor. The beta subunit is 44% homologous to the human platelet adhesion receptor subunit IIIa and 47% homologous to a leukocyte adhesion receptor beta subunit. The high degree of homology (85%) of the beta subunit with one of the polypeptides of a chicken adhesion receptor complex referred to as integrin complex strongly suggests that the latter polypeptide is the chicken homologue of the fibronectin receptor beta subunit. These receptor subunit homologies define a superfamily of adhesion receptors. The availability of the entire protein sequence for the fibronectin receptor will facilitate studies on the functions of these receptors. PMID:2958481

  12. Nitric oxide contributes to substance P-induced increases in lung rapidly adapting receptor activity in guinea-pigs.

    PubMed Central

    Joad, J P; Kott, K S; Bonham, A C

    1997-01-01

    1. Substance P induces fluid flux via nitric oxide, and fluid flux stimulates lung rapidly adapting receptors (RARs). We therefore proposed that nitric oxide contributes to substance P-evoked increases in RAR activity. Since substance P decreases dynamic compliance (Cdyn), which can stimulate RARs, we also determined whether nitric oxide contributed to substance P-induced effects on pulmonary function. 2. In anaesthetized guinea-pigs, the effects of substance P on RAR activity, Cdyn, pulmonary resistance (RL), and arterial blood pressure were measured before and after i.v. infusion of NG-methyl-L-arginine (L-NMMA; a nitric oxide synthase inhibitor), or L-NMMA followed by L-arginine (a nitric oxide precursor which reverses the effects of L-NMMA). 3. Substance P-evoked increases in RAR activity were blunted by L-NMMA (P = 0.006) but not by L-NMMA-L-arginine (P = 0.42). 4. Substance P-evoked decreases in Cdyn were slightly inhibited by L-NMMA (P = 0.02) and slightly enhanced by L-NMMA-L-arginine (P = 0.004). However, at the time at which L-NMMA maximally reduced substance P-induced RAR stimulation (the first 30 s), it did not change substance P-induced decreases in Cdyn. 5. Substance P-evoked increases in RL were not changed by L-NMMA (P = 0.10) and were enhanced by L-NMMA-L-arginine (P = 0.03). 6. L-NMMA-evoked increases in mean arterial blood pressure were reversed by L-arginine. Substance P-evoked decreases in mean arterial blood pressure were not changed by L-NMMA or by L-NMMA-L-arginine. 7. We conclude that nitric oxide contributes to substance P-evoked increases in RAR activity and that the increases are most probably independent of decreases in Cdyn. PMID:9379417

  13. A Review About Lycopene-Induced Nuclear Hormone Receptor Signalling in Inflammation and Lipid Metabolism via still Unknown Endogenous Apo-10´-Lycopenoids.

    PubMed

    Caris-Veyrat, Catherine; Garcia, Ada L; Reynaud, Eric; Lucas, Renata; Aydemir, Gamze; Rühl, Ralph

    2017-10-20

    Lycopene is the red pigment in tomatoes and tomato products and is an important dietary carotenoid found in the human organism. Lycopene-isomers, oxidative lycopene metabolites and apo-lycopenoids are found in the food matrix. Lycopene intake derived from tomato consumption is associated with alteration of lipid metabolism and a lower incidence of cardiovascular diseases (CVD). Lycopene is mainly described as a potent antioxidant but novel studies are shifting towards its metabolites and their capacity to mediate nuclear receptor signalling. Di-/tetra-hydro-derivatives of apo-10´-lycopenoic acid and apo-15´-lycopenoic acids are potential novel endogenous mammalian lycopene metabolites which may act as ligands for nuclear hormone mediated activation and signalling. In this review, we postulate that complex lycopene metabolism results in various lycopene metabolites which have the ability to mediate transactivation of various nuclear hormone receptors like RARs, RXRs and PPARs. A new mechanistic explanation of how tomato consumption could positively modulate inflammation and lipid metabolism is discussed.

  14. Evolution of the nuclear receptor superfamily: early diversification from an ancestral orphan receptor.

    PubMed

    Laudet, V

    1997-12-01

    From a database containing the published nuclear hormone receptor (NR) sequences I constructed an alignment of the C, D and E domains of these molecules. Using this alignment, I have performed tree reconstruction using both distance matrix and parsimony analysis. The robustness of each branch was estimated using bootstrap resampling methods. The trees constructed by these two methods gave congruent topologies. From these analyses I defined six NR subfamilies: (i) a large one clustering thyroid hormone receptors (TRs), retinoic acid receptors (RARs), peroxisome proliferator-activated receptors (PPARs), vitamin D receptors (VDRs) and ecdysone receptors (EcRs) as well as numerous orphan receptors such as RORs or Rev-erbs; (ii) one containing retinoid X receptors (RXRs) together with COUP, HNF4, tailless, TR2 and TR4 orphan receptors; (iii) one containing steroid receptors; (iv) one containing the NGFIB orphan receptors; (v) one containing FTZ-F1 orphan receptors; and finally (vi) one containing to date only one gene, the GCNF1 orphan receptor. The relationships between the six subfamilies are not known except for subfamilies I and IV which appear to be related. Interestingly, most of the liganded receptors appear to be derived when compared with orphan receptors. This suggests that the ligand-binding ability of NRs has been gained by orphan receptors during the course of evolution to give rise to the presently known receptors. The distribution into six subfamilies correlates with the known abilities of the various NRs to bind to DNA as homo- or heterodimers. For example, receptors heterodimerizing efficiently with RXR belong to the first or the fourth subfamilies. I suggest that the ability to heterodimerize evolved once, just before the separation of subfamilies I and IV and that the first NR was able to bind to DNA as a homodimer. From the study of NR sequences existing in vertebrates, arthropods and nematodes, I define two major steps of NR diversification: one

  15. Cloning and characterization of the hamster and guinea pig nicotinic acid receptors.

    PubMed

    Torhan, April Smith; Cheewatrakoolpong, Boonlert; Kwee, Lia; Greenfeder, Scott

    2007-09-01

    In this study, we present the identification and characterization of hamster and guinea pig nicotinic acid receptors. The hamster receptor shares approximately 80-90% identity with the nucleotide and amino acid sequences of human, mouse, and rat receptors. The guinea pig receptor shares 76-80% identity with the nucleotide and amino acid sequences of these other species. [(3)H]nicotinic acid binding affinity at guinea pig and hamster receptors is similar to that in human (dissociation constant = 121 nM for guinea pig, 72 nM for hamster, and 74 nM for human), as are potencies of nicotinic acid analogs in competition binding studies. Inhibition of forskolin-stimulated cAMP production by nicotinic acid and related analogs is also similar to the activity in the human receptor. Analysis of mRNA tissue distribution for the hamster and guinea pig nicotinic acid receptors shows expression across a number of tissues, with higher expression in adipose, lung, skeletal muscle, spleen, testis, and ovary.

  16. Towards Building an AOP-based Prenatal Developmental Toxicity Ontology (SOT)

    EPA Science Inventory

    Retinoid signaling plays an important role in embryo-fetal development and its disruption is broadly teratogenic. The retinoic acid (RA) pathway includes elements in retinoid metabolism and nuclear receptor (RAR, RXR) activation and thus serves as an excellent prototype for adver...

  17. Excitatory amino acid receptors and disease.

    PubMed

    Meldrum, B S

    1992-08-01

    Recent advances in the molecular biology of excitatory amino acid receptors are reviewed. Evidence that drugs blocking the excitatory action of glutamate at the N-methyl-D-aspartate (NMDA) and non-NMDA receptors may be of clinical use in epilepsy, Parkinson's disease, cerebral ischaemia and trauma, acquired immune deficiency syndrome (AIDS) encephalopathy and neuropathic pain is summarized.

  18. Accretion disks around neutron and strange stars in R+aR2 gravity

    NASA Astrophysics Data System (ADS)

    Staykov, Kalin V.; Doneva, Daniela D.; Yazadjiev, Stoytcho S.

    2016-08-01

    We study the electromagnetic spectrum of accretion disks around neutron and strange stars in R+aR2 gravity. Both static and rapidly rotating models are investigated. The results are compared with the General Relativistic results. We found difference between the results in both theories of about 50% for the electromagnetic flux and about 20% in the luminosity for models with equal mass and angular velocity in both theories. The observed differences are much lower for models rotating with Keplerian velocity and with equal masses.

  19. Tripartite Motif 24 (Trim24/Tif1α) Tumor Suppressor Protein Is a Novel Negative Regulator of Interferon (IFN)/Signal Transducers and Activators of Transcription (STAT) Signaling Pathway Acting through Retinoic Acid Receptor α (Rarα) Inhibition*

    PubMed Central

    Tisserand, Johan; Khetchoumian, Konstantin; Thibault, Christelle; Dembélé, Doulaye; Chambon, Pierre; Losson, Régine

    2011-01-01

    Recent genetic studies in mice have established that the nuclear receptor coregulator Trim24/Tif1α suppresses hepatocarcinogenesis by inhibiting retinoic acid receptor α (Rara)-dependent transcription and cell proliferation. However, Rara targets regulated by Trim24 remain unknown. We report that the loss of Trim24 resulted in interferon (IFN)/STAT pathway overactivation soon after birth (week 5). Despite a transient attenuation of this pathway by the induction of several IFN/STAT pathway repressors later in the disease, this phenomenon became more pronounced in tumors. Remarkably, Rara haplodeficiency, which suppresses tumorigenesis in Trim24−/− mice, prevented IFN/STAT overactivation. Moreover, together with Rara, Trim24 bound to the retinoic acid-responsive element of the Stat1 promoter and repressed its retinoic acid-induced transcription. Altogether, these results identify Trim24 as a novel negative regulator of the IFN/STAT pathway and suggest that this repression through Rara inhibition may prevent liver cancer. PMID:21768647

  20. Mechanisms for the activation of Toll-like receptor 2/4 by saturated fatty acids and inhibition by docosahexaenoic acid.

    PubMed

    Hwang, Daniel H; Kim, Jeong-A; Lee, Joo Young

    2016-08-15

    Saturated fatty acids can activate Toll-like receptor 2 (TLR2) and TLR4 but polyunsaturated fatty acids, particularly docosahexaenoic acid (DHA) inhibit the activation. Lipopolysaccharides (LPS) and lipopetides, ligands for TLR4 and TLR2, respectively, are acylated by saturated fatty acids. Removal of these fatty acids results in loss of their ligand activity suggesting that the saturated fatty acyl moieties are required for the receptor activation. X-ray crystallographic studies revealed that these saturated fatty acyl groups of the ligands directly occupy hydrophobic lipid binding domains of the receptors (or co-receptor) and induce the dimerization which is prerequisite for the receptor activation. Saturated fatty acids also induce the dimerization and translocation of TLR4 and TLR2 into lipid rafts in plasma membrane and this process is inhibited by DHA. Whether saturated fatty acids induce the dimerization of the receptors by interacting with these lipid binding domains is not known. Many experimental results suggest that saturated fatty acids promote the formation of lipid rafts and recruitment of TLRs into lipid rafts leading to ligand independent dimerization of the receptors. Such a mode of ligand independent receptor activation defies the conventional concept of ligand induced receptor activation; however, this may enable diverse non-microbial molecules with endogenous and dietary origins to modulate TLR-mediated immune responses. Emerging experimental evidence reveals that TLRs play a key role in bridging diet-induced endocrine and metabolic changes to immune responses. Published by Elsevier B.V.

  1. Role of the histone deacetylase complex in acute promyelocytic leukaemia.

    PubMed

    Lin, R J; Nagy, L; Inoue, S; Shao, W; Miller, W H; Evans, R M

    1998-02-19

    Non-liganded retinoic acid receptors (RARs) repress transcription of target genes by recruiting the histone deacetylase complex through a class of silencing mediators termed SMRT or N-CoR. Mutant forms of RARalpha, created by chromosomal translocations with either the PML (for promyelocytic leukaemia) or the PLZF (for promyelocytic leukaemia zinc finger) locus, are oncogenic and result in human acute promyelocytic leukaemia (APL). PML-RARalpha APL patients achieve complete remission following treatments with pharmacological doses of retinoic acids (RA); in contrast, PLZF-RARalpha patients respond very poorly, if at all. Here we report that the association of these two chimaeric receptors with the histone deacetylase (HDAC) complex helps to determine both the development of APL and the ability of patients to respond to retinoids. Consistent with these observations, inhibitors of histone deacetylase dramatically potentiate retinoid-induced differentiation of RA-sensitive, and restore retinoid responses of RA-resistant, APL cell lines. Our findings suggest that oncogenic RARs mediate leukaemogenesis through aberrant chromatin acetylation, and that pharmacological manipulation of nuclear receptor co-factors may be a useful approach in the treatment of human disease.

  2. Differential effects of phthalates on the testis and the liver.

    PubMed

    Bhattacharya, Nandini; Dufour, Jannette M; Vo, My-Nuong; Okita, Janice; Okita, Richard; Kim, Kwan Hee

    2005-03-01

    Phthalates have been shown to elicit contrasting effects on the testis and the liver, causing testicular degeneration and promoting abnormal hepatocyte proliferation and carcinogenesis. In the present study, we compared the effects of phthalates on testicular and liver cells to better understand the mechanisms by which phthalates cause testicular degeneration. In vivo treatment of rats with di-(2-ethylhexyl) phthalate (DEHP) caused a threefold increase of germ cell apoptosis in the testis, whereas apoptosis was not changed significantly in livers from the same animals. Western blot analyses revealed that peroxisome proliferator-activated receptor (PPAR) alpha is equally abundant in the liver and the testis, whereas PPAR gamma and retinoic acid receptor (RAR) alpha are expressed more in the testis. To determine whether the principal metabolite of DEHP, mono-(2-ethylhexyl) phthalate (MEHP), or a strong peroxisome proliferator, 4-chloro-6(2,3-xylindino)-2-pyrimidinylthioacetic acid (Wy-14,643), have a differential effect in Sertoli and liver cells by altering the function of RAR alpha and PPARs, their nuclear trafficking patterns were compared in Sertoli and liver cells after treatment. Both MEHP and Wy-14,643 increased the nuclear localization of PPAR alpha and PPAR gamma in Sertoli cells, but they decreased the nuclear localization of RAR alpha, as previously shown. Both PPAR alpha and PPAR gamma were in the nucleus and cytoplasm of liver cells, but RAR alpha was predominant in the cytoplasm, regardless of the treatment. At the molecular level, MEHP and Wy-14,643 reduced the amount of phosphorylated mitogen-activated protein kinase (activated MAPK) in Sertoli cells. In comparison, both MEHP and Wy-14,643 increased phosphorylated MAPK in liver cells. These results suggest that phthalates may cause contrasting effects on the testis and the liver by differential activation of the MAPK pathway, RAR alpha, PPAR alpha, and PPAR gamma in these organs.

  3. Lung congestion augments the responses of cells in the rapidly adapting receptor pathway to cigarette smoke in rabbit.

    PubMed Central

    Zhang, Z; Bonham, A C

    1995-01-01

    1. We examined the effects of cigarette smoke, inhaled alone and during mild pulmonary venous congestion, on the activity of fifty-three neurones in the nucleus tractus solitarii (NTS) that were excited by input from pulmonary rapidly adapting receptors (RAR). Ten neurones excited by slowly adapting stretch receptors (SAR) were also studied. 2. Extracellular recordings of RAR-activated neurones were recorded in alpha-chloralose anaesthetized rabbits. Smoke from low- and high-nicotine cigarettes was delivered through a ventilator. Mild pulmonary venous congestion was produced by inflating a balloon in the left atrium. 3. Inhalation of three breaths of smoke from low-nicotine cigarettes increased the activity of fifty-one out of fifty-three RAR-activated neurones from 5.9 +/- 1.0 to 14.4 +/- 2.1 spikes breath-1 (P < 0.05). 4. The responses of fifteen neurones were compared with smoke inhaled alone or during mild pulmonary venous congestion. Smoke alone increased unit activity from 6.8 +/- 2.3 to 12.6 +/- 3.7 spikes breath-1 (P < 0.05). Small increases in left atrial pressure (2.0 +/- 0.5 mmHg) had no effect on baseline unit activity (7.6 +/- 2.11 vs. 7.7 +/- 2.3 spikes breath-1; P > 0.05), but enhanced the responses to smoke, increasing the activity from 7.6 +/- 2.1 to 17.1 +/- 4.8 spikes breath-1 (P < 0.05). The response was greater than to smoke alone (P < 0.05). 5. Of ten SAR-activated neurones, seven failed to respond to inhaled cigarette smoke, two were excited and one was inhibited. Pulmonary venous congestion had no effect on the unit activity before and after smoke (n = 4 neurones). 6. We conclude that smoke-evoked excitation of RAR lower-order neurones is augmented by pulmonary venous congestion. Images Figure 3 PMID:7602520

  4. Retinoic acid induces nuclear accumulation of Raf1 during differentiation of HL-60 cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Smith, James; Bunaciu, Rodica P.; Reiterer, Gudrun

    All trans-retinoic acid (RA) is a standard therapeutic agent used in differentiation induction therapy treatment of acute promyelocytic leukemia (APL). RA and its metabolites use a diverse set of signal transduction pathways during the differentiation program. In addition to the direct transcriptional targets of the nuclear RAR and RXR receptors, signals derived from membrane receptors and the Raf-MEK-ERK pathway are required. Raf1 phosphorylation and the prolonged activation of Raf1 persisting during the entire differentiation process are required for RA-dependent differentiation of HL-60 cells. Here we identify a nuclear redistribution of Raf1 during the RA-induced differentiation of HL-60 cells. In addition,more » the nuclear accumulation of Raf1 correlates with an increase in Raf1 phosphorylated at serine 621. The serine 621 phosphorylated Raf1 is predominantly localized in the nucleus. The RA-dependent nuclear accumulation of Raf1 suggests a novel nuclear role for Raf1 during the differentiation process.« less

  5. Application of GPCR Structures for Modelling of Free Fatty Acid Receptors.

    PubMed

    Tikhonova, Irina G

    2017-01-01

    Five G protein-coupled receptors (GPCRs) have been identified to be activated by free fatty acids (FFA). Among them, FFA1 (GPR40) and FFA4 (GPR120) bind long-chain fatty acids, FFA2 (GPR43) and FFA3 (GPR41) bind short-chain fatty acids and GPR84 binds medium-chain fatty acids. Free fatty acid receptors have now emerged as potential targets for the treatment of diabetes, obesity and immune diseases. The recent progress in crystallography of GPCRs has now enabled the elucidation of the structure of FFA1 and provided reliable templates for homology modelling of other FFA receptors. Analysis of the crystal structure and improved homology models, along with mutagenesis data and structure activity, highlighted an unusual arginine charge-pairing interaction in FFA1-3 for receptor modulation, distinct structural features for ligand binding to FFA1 and FFA4 and an arginine of the second extracellular loop as a possible anchoring point for FFA at GPR84. Structural data will be helpful for searching novel small-molecule modulators at the FFA receptors.

  6. Pontocerebellar hypoplasia type 6 caused by mutations in RARS2: definition of the clinical spectrum and molecular findings in five patients.

    PubMed

    Cassandrini, Denise; Cilio, Maria Roberta; Bianchi, Marzia; Doimo, Mara; Balestri, Martina; Tessa, Alessandra; Rizza, Teresa; Sartori, Geppo; Meschini, Maria Chiara; Nesti, Claudia; Tozzi, Giulia; Petruzzella, Vittoria; Piemonte, Fiorella; Bisceglia, Luigi; Bruno, Claudio; Dionisi-Vici, Carlo; D'Amico, Adele; Fattori, Fabiana; Carrozzo, Rosalba; Salviati, Leonardo; Santorelli, Filippo M; Bertini, Enrico

    2013-01-01

    Recessive mutations in the mitochondrial arginyl-transfer RNA synthetase (RARS2) gene have been associated with early onset encephalopathy with signs of oxidative phosphorylation defects classified as pontocerebellar hypoplasia 6. We describe clinical, neuroimaging and molecular features on five patients from three unrelated families who displayed mutations in RARS2. All patients rapidly developed a neonatal or early-infantile epileptic encephalopathy with intractable seizures. The long-term follow-up revealed a virtual absence of psychomotor development, progressive microcephaly, and feeding difficulties. Mitochondrial respiratory chain enzymes in muscle and fibroblasts were normal in two. Blood and CSF lactate was abnormally elevated in all five patients at early stages while appearing only occasionally abnormal with the progression of the disease. Cerebellar vermis hypoplasia with normal aspect of the cerebral and cerebellar hemispheres appeared within the first months of life at brain MRI. In three patients follow-up neuroimaging revealed a progressive pontocerebellar and cerebral cortical atrophy. Molecular investigations of RARS2 disclosed the c.25A>G/p.I9V and the c.1586+3A>T in family A, the c.734G>A/p.R245Q and the c.1406G>A/p.R469H in family B, and the c.721T>A/p.W241R and c.35A>G/p.Q12R in family C. Functional complementation studies in Saccharomyces cerevisiae showed that mutation MSR1-R531H (equivalent to human p.R469H) abolished respiration whereas the MSR1-R306Q strain (corresponding to p.R245Q) displayed a reduced growth on non-fermentable YPG medium. Although mutations functionally disrupted yeast we found a relatively well preserved arginine aminoacylation of mitochondrial tRNA. Clinical and neuroimaging findings are important clues to raise suspicion and to reach diagnostic accuracy for RARS2 mutations considering that biochemical abnormalities may be absent in muscle biopsy.

  7. Bile acid receptors link nutrient sensing to metabolic regulation

    PubMed Central

    Li, Jibiao; Li, Tiangang

    2017-01-01

    Non-alcoholic fatty liver disease (NAFLD) is a common liver disease in Western populations. Non-alcoholic steatohepatitis (NASH) is a more debilitating form of NAFLD characterized by hepatocellular injury and inflammation, which significantly increase the risk of end-stage liver and cardiovascular diseases. Unfortunately, there are no available drug therapies for NASH. Bile acids are physiological detergent molecules that are synthesized from cholesterol exclusively in the hepatocytes. Bile acids circulate between the liver and intestine, where they are required for cholesterol solubilization in the bile and dietary fat emulsification in the gut. Bile acids also act as signaling molecules that regulate metabolic homeostasis and inflammatory processes. Many of these effects are mediated by the bile acid-activated nuclear receptor farnesoid X receptor (FXR) and the G protein-coupled receptor TGR5. Nutrient signaling regulates hepatic bile acid synthesis and circulating plasma bile acid concentrations, which in turn control metabolic homeostasis. The FXR agonist obeticholic acid has had beneficial effects on NASH in recent clinical trials. Preclinical studies have suggested that the TGR5 agonist and the FXR/TGR5 dual agonist are also potential therapies for metabolic liver diseases. Extensive studies in the past few decades have significantly improved our understanding of the metabolic regulatory function of bile acids, which has provided the molecular basis for developing promising bile acid-based therapeutic agents for NASH treatment. PMID:29098111

  8. Annotation of the Nuclear Receptors in an Estuarine Fish species, Fundulus heteroclitus

    PubMed Central

    Baldwin, William S.; Boswell, W. Tyler; Ginjupalli, Gautam; Litoff, Elizabeth J.

    2017-01-01

    The nuclear receptors (NRs) are ligand-dependent transcription factors that respond to various internal as well as external cues such as nutrients, pheromones, and steroid hormones that play crucial roles in regulation and maintenance of homeostasis and orchestrating the physiological and stress responses of an organism. We annotated the Fundulus heteroclitus (mummichog; Atlantic killifish) nuclear receptors. Mummichog are a non-migratory, estuarine fish with a limited home range often used in environmental research as a field model for studying ecological and evolutionary responses to variable environmental conditions such as salinity, oxygen, temperature, pH, and toxic compounds because of their hardiness. F. heteroclitus have at least 74 NRs spanning all seven gene subfamilies. F. heteroclitus is unique in that no RXRα member was found within the genome. Interestingly, some of the NRs are highly conserved between species, while others show a higher degree of divergence such as PXR, SF1, and ARα. Fundulus like other fish species show expansion of the RAR (NR1B), Rev-erb (NR1D), ROR (NR1F), COUPTF (NR2F), ERR (NR3B), RXR (NR2B), and to a lesser extent the NGF (NR4A), and NR3C steroid receptors (GR/AR). Of particular interest is the co-expansion of opposing NRs, Reverb-ROR, and RAR/RXR-COUPTF. PMID:28804711

  9. Comparative effects of overproducing the AraC-type transcriptional regulators MarA, SoxS, RarA and RamA on antimicrobial drug susceptibility in Klebsiella pneumoniae.

    PubMed

    Jiménez-Castellanos, Juan-Carlos; Wan Ahmad Kamil, Wan Nur Ismah; Cheung, Ching Hei Phoebe; Tobin, Maryann S; Brown, James; Isaac, Sophie G; Heesom, Kate J; Schneiders, Thamarai; Avison, Matthew B

    2016-07-01

    In Klebsiella pneumoniae, overproduction of RamA and RarA leads to increased MICs of various antibiotics; MarA and SoxS are predicted to perform a similar function. We have compared the relative effects of overproducing these four AraC-type regulators on envelope permeability (a combination of outer membrane permeability and efflux), efflux pump and porin production, and antibiotic susceptibility in K. pneumoniae. Regulators were overproduced using a pBAD expression vector. Antibiotic susceptibility was measured using disc testing. Envelope permeability was estimated using a fluorescent dye accumulation assay. Porin and efflux pump production was quantified using proteomics and validated using real-time quantitative RT-PCR. Envelope permeability and antibiotic disc inhibition zone diameters both reduced during overproduction of RamA and to a lesser extent RarA or SoxS, but did not change following overproduction of MarA. These effects were associated with overproduction of the efflux pumps AcrAB (for RamA and SoxS) and OqxAB (for RamA and RarA) and the outer membrane protein TolC (for all regulators). Effects on porin production were strain specific. RamA is the most potent regulator of antibiotic permeability in K. pneumoniae, followed by RarA then SoxS, with MarA having very little effect. This observed relative potency correlates well with the frequency at which these regulators are reportedly overproduced in clinical isolates. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  10. Azadirachtin Interacts with Retinoic Acid Receptors and Inhibits Retinoic Acid-mediated Biological Responses*

    PubMed Central

    Thoh, Maikho; Babajan, Banaganapalli; Raghavendra, Pongali B.; Sureshkumar, Chitta; Manna, Sunil K.

    2011-01-01

    Considering the role of retinoids in regulation of more than 500 genes involved in cell cycle and growth arrest, a detailed understanding of the mechanism and its regulation is useful for therapy. The extract of the medicinal plant Neem (Azadirachta indica) is used against several ailments especially for anti-inflammatory, anti-itching, spermicidal, anticancer, and insecticidal activities. In this report we prove the detailed mechanism on the regulation of retinoic acid-mediated cell signaling by azadirachtin, active components of neem extract. Azadirachtin repressed all trans-retinoic acid (ATRA)-mediated nuclear transcription factor κB (NF-κB) activation, not the DNA binding but the NF-κB-dependent gene expression. It did not inhibit IκBα degradation, IκBα kinase activity, or p65 phosphorylation and its nuclear translocation but inhibited NF-κB-dependent reporter gene expression. Azadirachtin inhibited TRAF6-mediated, but not TRAF2-mediated NF-κB activation. It inhibited ATRA-induced Sp1 and CREB (cAMP-response element-binding protein) DNA binding. Azadirachtin inhibited ATRA binding with retinoid receptors, which is supported by biochemical and in silico evidences. Azadirachtin showed strong interaction with retinoid receptors. It suppressed ATRA-mediated removal of retinoid receptors, bound with DNA by inhibiting ATRA binding to its receptors. Overall, our data suggest that azadirachtin interacts with retinoic acid receptors and suppresses ATRA binding, inhibits falling off the receptors, and activates transcription factors like CREB, Sp1, NF-κB, etc. Thus, azadirachtin exerts anti-inflammatory and anti-metastatic responses by a novel pathway that would be beneficial for further anti-inflammatory and anti-cancer therapies. PMID:21127062

  11. Azadirachtin interacts with retinoic acid receptors and inhibits retinoic acid-mediated biological responses.

    PubMed

    Thoh, Maikho; Babajan, Banaganapalli; Raghavendra, Pongali B; Sureshkumar, Chitta; Manna, Sunil K

    2011-02-11

    Considering the role of retinoids in regulation of more than 500 genes involved in cell cycle and growth arrest, a detailed understanding of the mechanism and its regulation is useful for therapy. The extract of the medicinal plant Neem (Azadirachta indica) is used against several ailments especially for anti-inflammatory, anti-itching, spermicidal, anticancer, and insecticidal activities. In this report we prove the detailed mechanism on the regulation of retinoic acid-mediated cell signaling by azadirachtin, active components of neem extract. Azadirachtin repressed all trans-retinoic acid (ATRA)-mediated nuclear transcription factor κB (NF-κB) activation, not the DNA binding but the NF-κB-dependent gene expression. It did not inhibit IκBα degradation, IκBα kinase activity, or p65 phosphorylation and its nuclear translocation but inhibited NF-κB-dependent reporter gene expression. Azadirachtin inhibited TRAF6-mediated, but not TRAF2-mediated NF-κB activation. It inhibited ATRA-induced Sp1 and CREB (cAMP-response element-binding protein) DNA binding. Azadirachtin inhibited ATRA binding with retinoid receptors, which is supported by biochemical and in silico evidences. Azadirachtin showed strong interaction with retinoid receptors. It suppressed ATRA-mediated removal of retinoid receptors, bound with DNA by inhibiting ATRA binding to its receptors. Overall, our data suggest that azadirachtin interacts with retinoic acid receptors and suppresses ATRA binding, inhibits falling off the receptors, and activates transcription factors like CREB, Sp1, NF-κB, etc. Thus, azadirachtin exerts anti-inflammatory and anti-metastatic responses by a novel pathway that would be beneficial for further anti-inflammatory and anti-cancer therapies.

  12. Unsaturated free fatty acids increase benzodiazepine receptor agonist binding depending on the subunit composition of the GABAA receptor complex.

    PubMed

    Witt, M R; Westh-Hansen, S E; Rasmussen, P B; Hastrup, S; Nielsen, M

    1996-11-01

    It has been shown previously that unsaturated free fatty acids (FFAs) strongly enhance the binding of agonist benzodiazepine receptor ligands and GABAA receptor ligands in the CNS in vitro. To investigate the selectivity of this effect, recombinant human GABAA/benzodiazepine receptor complexes formed by different subunit compositions (alpha x beta y gamma 2, x = 1, 2, 3, and 5; y = 1, 2, and 3) were expressed using the baculovirus-transfected Sf9 insect cell system. At 10(-4) M, unsaturated FFAs, particularly arachidonic (20:4) and docosahexaenoic (22:6) acids, strongly stimulated (> 200% of control values) the binding of [3H]flunitrazepam ([3H]FNM) to the alpha 3 beta 2 gamma 2 receptor combination in whole cell preparations. No effect or small increases in levels of unsaturated FFAs on [3H]FNM binding to alpha 1 beta x gamma 2 and alpha 2 beta x gamma 2 receptor combinations were observed, and weak effects (130% of control values) were detected using the alpha 5 beta 2 gamma 2 receptor combination. The saturated FFAs, stearic and palmitic acids, were without effect on [3H]FNM binding to any combination of receptor complexes. The hydroxylated unsaturated FFAs, ricinoleic and ricinelaidic acids, were shown to decrease the binding of [3H]FNM only if an alpha 1 beta 2 gamma 2 receptor combination was used. Given the heterogeneity of the GABAA/ benzodiazepine receptor subunit distribution in the CNS, the effects of FFAs on the benzodiazepine receptor can be assumed to vary at both cellular and regional levels.

  13. The quaternary architecture of RARβ–RXRα heterodimer facilitates domain–domain signal transmission

    DOE PAGES

    Chandra, Vikas; Wu, Dalei; Li, Sheng; ...

    2017-10-11

    Assessing the physical connections and allosteric communications in multi-domain nuclear receptor (NR) polypeptides has remained challenging, with few crystal structures available to show their overall structural organizations. Here we report the quaternary architecture of multi-domain retinoic acid receptor beta-retinoic X receptor alpha (RAR beta-RXR alpha) heterodimer bound to DNA, ligands and coactivator peptides, examined through crystallographic, hydrogen-deuterium exchange mass spectrometry, mutagenesis and functional studies. The RAR beta ligand-binding domain (LBD) and DNA-binding domain (DBD) are physically connected to foster allosteric signal transmission between them. Direct comparisons among all the multi-domain NRs studied crystallographically to date show significant variations within theirmore » quaternary architectures, rather than a common architecture adhering to strict rules. RXR remains flexible and adaptive by maintaining loosely organized domains, while its hetero-dimerization partners use a surface patch on their LBDs to form domain-domain interactions with DBDs.« less

  14. The quaternary architecture of RARβ–RXRα heterodimer facilitates domain–domain signal transmission

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chandra, Vikas; Wu, Dalei; Li, Sheng

    Assessing the physical connections and allosteric communications in multi-domain nuclear receptor (NR) polypeptides has remained challenging, with few crystal structures available to show their overall structural organizations. Here we report the quaternary architecture of multi-domain retinoic acid receptor beta-retinoic X receptor alpha (RAR beta-RXR alpha) heterodimer bound to DNA, ligands and coactivator peptides, examined through crystallographic, hydrogen-deuterium exchange mass spectrometry, mutagenesis and functional studies. The RAR beta ligand-binding domain (LBD) and DNA-binding domain (DBD) are physically connected to foster allosteric signal transmission between them. Direct comparisons among all the multi-domain NRs studied crystallographically to date show significant variations within theirmore » quaternary architectures, rather than a common architecture adhering to strict rules. RXR remains flexible and adaptive by maintaining loosely organized domains, while its hetero-dimerization partners use a surface patch on their LBDs to form domain-domain interactions with DBDs.« less

  15. Amino acid sensing in hypothalamic tanycytes via umami taste receptors.

    PubMed

    Lazutkaite, Greta; Soldà, Alice; Lossow, Kristina; Meyerhof, Wolfgang; Dale, Nicholas

    2017-11-01

    Hypothalamic tanycytes are glial cells that line the wall of the third ventricle and contact the cerebrospinal fluid (CSF). While they are known to detect glucose in the CSF we now show that tanycytes also detect amino acids, important nutrients that signal satiety. Ca 2+ imaging and ATP biosensing were used to detect tanycyte responses to l-amino acids. The downstream pathway of the responses was determined using ATP receptor antagonists and channel blockers. The receptors were characterized using mice lacking the Tas1r1 gene, as well as an mGluR4 receptor antagonist. Amino acids such as Arg, Lys, and Ala evoke Ca 2+ signals in tanycytes and evoke the release of ATP via pannexin 1 and CalHM1, which amplifies the signal via a P2 receptor dependent mechanism. Tanycytes from mice lacking the Tas1r1 gene had diminished responses to lysine and arginine but not alanine. Antagonists of mGluR4 greatly reduced the responses to alanine and lysine. Two receptors previously implicated in taste cells, the Tas1r1/Tas1r3 heterodimer and mGluR4, contribute to the detection of a range of amino acids by tanycytes in CSF. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

  16. Dexmedetomidine Prevents Excessive γ-Aminobutyric Acid Type A Receptor Function after Anesthesia.

    PubMed

    Wang, Dian-Shi; Kaneshwaran, Kirusanthy; Lei, Gang; Mostafa, Fariya; Wang, Junhui; Lecker, Irene; Avramescu, Sinziana; Xie, Yu-Feng; Chan, Nathan K; Fernandez-Escobar, Alejandro; Woo, Junsung; Chan, Darren; Ramsey, Amy J; Sivak, Jeremy M; Lee, C Justin; Bonin, Robert P; Orser, Beverley A

    2018-06-08

    Postoperative delirium is associated with poor long-term outcomes and increased mortality. General anesthetic drugs may contribute to delirium because they increase cell-surface expression and function of α5 subunit-containing γ-aminobutyric acid type A receptors, an effect that persists long after the drugs have been eliminated. Dexmedetomidine, an α2 adrenergic receptor agonist, prevents delirium in patients and reduces cognitive deficits in animals. Thus, it was postulated that dexmedetomidine prevents excessive function of α5 γ-aminobutyric acid type A receptors. Injectable (etomidate) and inhaled (sevoflurane) anesthetic drugs were studied using cultured murine hippocampal neurons, cultured murine and human cortical astrocytes, and ex vivo murine hippocampal slices. γ-Aminobutyric acid type A receptor function and cell-signaling pathways were studied using electrophysiologic and biochemical methods. Memory and problem-solving behaviors were also studied. The etomidate-induced sustained increase in α5 γ-aminobutyric acid type A receptor cell-surface expression was reduced by dexmedetomidine (mean ± SD, etomidate: 146.4 ± 51.6% vs. etomidate + dexmedetomidine: 118.4 ± 39.1% of control, n = 8 each). Dexmedetomidine also reduced the persistent increase in tonic inhibitory current in hippocampal neurons (etomidate: 1.44 ± 0.33 pA/pF, n = 10; etomidate + dexmedetomidine: 1.01 ± 0.45 pA/pF, n = 9). Similarly, dexmedetomidine prevented a sevoflurane-induced increase in the tonic current. Dexmedetomidine stimulated astrocytes to release brain-derived neurotrophic factor, which acted as a paracrine factor to reduce excessive α5 γ-aminobutyric acid type A receptor function in neurons. Finally, dexmedetomidine attenuated memory and problem-solving deficits after anesthesia. Dexmedetomidine prevented excessive α5 γ-aminobutyric acid type A receptor function after anesthesia. This novel α2 adrenergic receptor- and brain-derived neurotrophic factor

  17. Helminthosporic acid functions as an agonist for gibberellin receptor.

    PubMed

    Miyazaki, Sho; Jiang, Kai; Kobayashi, Masatomo; Asami, Tadao; Nakajima, Masatoshi

    2017-11-01

    Helminthosporol was isolated from a fungus, Helminthosporium sativum, as a natural plant growth regulator in 1963. It showed gibberellin-like bioactivity that stimulated the growth of the second leaf sheath of rice. After studying the structure-activity relationship between the compound and some synthesized analogs, it was found that helminthosporic acid (H-acid) has higher gibberellin-like activity and chemical stability than helminthosporol. In this study, we showed that (1) H-acid displays gibberellin-like activities not only in rice but also in Arabidopsis, (2) it regulates the expression of gibberellin-related genes, (3) it induces DELLA degradation through binding with a gibberellin receptor (GID1), and (4) it forms the GID1-(H-acid)-DELLA complex to transduce the gibberellin signal in the same manner as gibberellin. This work shows that the H-acid mode of action acts as an agonist for gibberellin receptor.

  18. Transcriptional regulation of genes involved in retinoic acid metabolism in Senegalese sole larvae.

    PubMed

    Boglino, Anaïs; Ponce, Marian; Cousin, Xavier; Gisbert, Enric; Manchado, Manuel

    2017-01-01

    The aim of this study was the characterization of transcriptional regulatory pathways mediated by retinoic acid (RA) in Senegalese sole larvae. For this purpose, pre-metamorphic larvae were treated with a low concentration of DEAB, an inhibitor of RALDH enzyme, until the end of metamorphosis. No differences in growth, eye migration or survival were observed. Nevertheless, gene expression analysis revealed a total of 20 transcripts differentially expressed during larval development and only six related with DEAB treatments directly involved in RA metabolism and actions (rdh10a, aldh1a2, crbp1, igf2r, rarg and cyp26a1) to adapt to a low-RA environment. In a second experiment, post-metamorphic larvae were exposed to the all-trans RA (atRA) observing an opposite regulation for those genes involved in RA synthesis and degradation (rdh10a, aldh1a2, crbp1 and cyp26a1) as well as other related with thyroid- (dio2) and IGF-axes (igfbp1, igf2r and igfbp5) to balance RA levels. In a third experiment, DEAB-pretreated post-metamorphic larvae were exposed to atRA and TTNPB (a specific RAR agonist). Both drugs down-regulated rdh10a and aldh1a2 and up-regulated cyp26a1 expression demonstrating their important role in RA homeostasis. Moreover, five retinoic receptors that mediate RA actions, the thyroid receptor thrb, and five IGF binding proteins changed differentially their expression. Overall, this study demonstrates that exogenous RA modulates the expression of some genes involved in the RA synthesis, degradation and cellular transport through RAR-mediated regulatory pathways establishing a negative feedback regulatory mechanism necessary to balance endogenous RA levels and gradients. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Identification of COUP-TFII Orphan Nuclear Receptor as a Retinoic Acid-Activated Receptor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kruse, Schoen W; Suino-Powell, Kelly; Zhou, X Edward

    2010-01-12

    The chicken ovalbumin upstream promoter-transcription factors (COUP-TFI and II) make up the most conserved subfamily of nuclear receptors that play key roles in angiogenesis, neuronal development, organogenesis, cell fate determination, and metabolic homeostasis. Although the biological functions of COUP-TFs have been studied extensively, little is known of their structural features or aspects of ligand regulation. Here we report the ligand-free 1.48 {angstrom} crystal structure of the human COUP-TFII ligand-binding domain. The structure reveals an autorepressed conformation of the receptor, where helix {alpha}10 is bent into the ligand-binding pocket and the activation function-2 helix is folded into the cofactor binding site,more » thus preventing the recruitment of coactivators. In contrast, in multiple cell lines, COUP-TFII exhibits constitutive transcriptional activity, which can be further potentiated by nuclear receptor coactivators. Mutations designed to disrupt cofactor binding, dimerization, and ligand binding, substantially reduce the COUP-TFII transcriptional activity. Importantly, retinoid acids are able to promote COUP-TFII to recruit coactivators and activate a COUP-TF reporter construct. Although the concentration needed is higher than the physiological levels of retinoic acids, these findings demonstrate that COUP-TFII is a ligand-regulated nuclear receptor, in which ligands activate the receptor by releasing it from the autorepressed conformation.« less

  20. A prospective study of common variants in the RAR-related orphan receptor alpha (RORalpha) gene and risk of neovascular age-related macular degeneration

    PubMed Central

    Schaumberg, Debra A.; Chasman, Daniel; Morrison, Margaux A.; Adams, Scott M.; Guo, Qun; Hunter, David J.; Hankinson, Susan E.; DeAngelis, Margaret M.

    2010-01-01

    Objectives The RAR-related orphan receptor alpha (RORalpha) gene is implicated as a candidate for age-related macular degeneration (AMD) through a previous microarray expression study, linkage data, biological plausibility, and two clinic-based cross sectional studies. We aimed to determine if common variants in RORalpha predict future risk of neovascular AMD. Methods We measured genotypes for 18 variants in intron 1 of the RORalpha gene among 164 cases who developed neovascular AMD and 485 age- and sex-matched controls in a prospective nested case-control study within the Nurses’ Health Study and the Health Professionals Follow-up Study. We determined the incidence rate ratios (IRR) and 95% confidence intervals (CI) for neovascular AMD for each variant, and examined interactions with other AMD-associated variants and modifiable risk factors. Results We identified a single SNP (rs12900948) that was significantly associated with increased incidence of neovascular AMD. Participants with one and two copies of the “G” allele were 1.73 (CI= 1.32–2.27) and 2.99 (CI=1.74–5.14) times more likely to develop neovascular AMD. Individuals homozygous for both the “G” allele of rs12900948 and ARMS2 A69S had a 40.8-fold increased risk of neovascular AMD (CI=10.1–164; P for interaction=0.017). Cigarette smokers who carried two copies of the “G” allele had a 9.89-fold risk of neovascular AMD, but the interaction was not significant (P=0.08). We identified a significant AMD-associated haplotype block containing SNPs rs730754, rs8034864, and rs12900948, with P-values for ACA=1.16 × 10−9, ACG=5.85 × 10−12, and GAA=0.0001 when compared to all other haplotypes. Conclusion Common variants and haplotypes within the RORalpha gene appear to act synergistically with the ARMS2 A69S polymorphism to increase risk of neovascular AMD. These data add further evidence of a high level of complexity linking genetic and modifiable risk factors to AMD development and should

  1. Oral administration of oleanolic acid, isolated from Swertia mussotii Franch, attenuates liver injury, inflammation, and cholestasis in bile duct-ligated rats

    PubMed Central

    Chai, Jin; Du, Xiaohuang; Chen, Sheng; Feng, XinChan; Cheng, Ying; Zhang, Liangjun; Gao, Yu; Li, Shaoxue; He, Xiaochong; Wang, Rongquan; Zhou, Xiangdong; Yang, Yong; Luo, Weizao; Chen, Wensheng

    2015-01-01

    Background & aims: Oleanolic acid is abundantly distributed in Swertia mussotii Franch, a Chinese traditional herb for the treatment of jaundice. However, the hepatoprotective role of oleanolic acid in obstructive cholestasis and its underlying molecular mechanism are unclear. Methods: Normal rats and bile duct-ligated (BDL) rats were given oleanolic acid and serum biochemistry, bile salts, and pro-inflammatory factors were measured, as well as the expression levels of liver bile acid synthesis and detoxification enzymes, membrane transporters, nuclear receptors, and transcriptional factors. Results: Oral administration of oleanolic acid at 100 mg/kg did not cause rat liver injury. However, it significantly reduced the serum levels of alanine aminotransferase (ALT) on days 7 and 14, aspartate aminotransferase (AST) and TNF-α on day 14, and alkaline phosphatase (ALP) and IL-1β on days 3, 7, and 14 in the BDL rats. Furthermore, the serum levels of total bile acid (TBA) and bile acids, including CDCA, CA, DCA, and Tα/βMCA were significantly reduced by oleanolic acid on day 3 in the BDL rats. In addition, the expression levels of detoxification enzymes Cyp3a, Ugt2b, Sult2a1, Gsta1-2, and Gstm1-3, membrane transporters Mrp3, Mrp4, Ostβ, Mdr1, Mdr2, and Bsep, nuclear receptors Pxr, Vdr, Hnf4α, Rxrα, Rarα, Lxr, and Lrh-1, and transcriptional factors Nrf2, Hnf3β, and Ahr were significantly increased in oleanolic acid-treated rats. Conclusion: We demonstrated that the oral administration of oleanolic acid attenuates liver injury, inflammation, and cholestasis in BDL rats. The anti-cholestatic effect may be associated with the induction of hepatic detoxification enzymes and efflux transporters mediated by nuclear receptors and transcriptional factors. PMID:25932098

  2. Retinoid Pathway and Cancer Therapeutics

    PubMed Central

    Bushue, Nathan; Wan, Yu-Jui Yvonne

    2010-01-01

    The retinoids are a class of compounds that are structurally related to vitamin A. Retinoic acid, which is the active metabolite of retinol, regulates a wide range of biological processes including development, differentiation, proliferation, and apoptosis. Retinoids exert their effects through a variety of binding proteins including cellular retinol binding protein (CRBP), retinol-binding proteins (RBP), cellular retinoic acid-binding protein (CRABP), and nuclear receptors i.e. retinoic acid receptor (RAR) and retinoid × receptor (RXR). Because of the pleiotropic effects of retinoids, understanding the function of these binding proteins and nuclear receptors assists us in developing compounds that have specific effects. This review summarizes our current understanding of how retinoids are processed and act with the emphasis on the application of retinoids in cancer treatment and prevention. PMID:20654663

  3. Modulation of GABAA receptors by valerian extracts is related to the content of valerenic acid.

    PubMed

    Trauner, Gabriele; Khom, Sophia; Baburin, Igor; Benedek, Birgit; Hering, Steffen; Kopp, Brigitte

    2008-01-01

    Valeriana Officinalis L . is a traditionally used sleep remedy, however, the mechanism of action and the substances responsible for its sedative and sleep-enhancing properties are not fully understood. As we previously identified valerenic acid as a subunit-specific allosteric modulator of GABAA receptors, we now investigated the relation between modulation of GABAA receptors by Valerian extracts of different polarity and the content of sesquiterpenic acids (valerenic acid, acetoxyvalerenic acid). All extracts were analysed by HPLC concerning the content of sesquiterpenic acids. GABAA receptors composed of alpha 1, beta 2 and gamma 2S subunits were expressed in Xenopus laevis oocytes and the modulation of chloride currents through GABAA receptors (IGABA) by Valerian extracts was investigated using the two-microelectrode voltage clamp technique. Apolar extracts induced a significant enhancement of IGABA, whereas polar extracts showed no effect. These results were confirmed by fractionating a highly active ethyl acetate extract: again fractions with high contents of valerenic acid exhibited strong receptor activation. In addition, removal of sesquiterpenic acids from the ethyl acetate extract led to a loss of I (GABA) enhancement. In conclusion, our data show that the extent of GABAA receptor modulation by Valerian extracts is related to the content of valerenic acid.

  4. Liver X receptor alpha regulates fatty acid synthase expression in chicken.

    PubMed

    Demeure, O; Duby, C; Desert, C; Assaf, S; Hazard, D; Guillou, H; Lagarrigue, S

    2009-12-01

    Liver X receptor alpha (LXRalpha), also referred to as nuclear receptor subfamily 1, group H, member 3 is a member of the nuclear hormone receptor superfamily, and has recently been shown to act as a master transcription factor governing hepatic lipogenesis in mammals. Liver X receptor alpha directly regulates both the expression of other lipogenic transcription factors and the expression of lipogenic enzymes, thereby enhancing hepatic fatty acid synthesis (FASN). In birds, like in humans, fatty acid synthesis primarily occurs in the liver. Whether LXRalpha is involved in hepatic regulation of lipogenic genes remained to be investigated in this species. Here we show that fatty acid synthase and the expression of other lipogenic genes (sterol regulatory element binding protein 1 and steroyl coenzyme A desaturase 1) are induced in chicken hepatoma cells in response to a pharmacological liver X receptor agonist, T0901317. A detailed analysis of the chicken FASN promoter revealed a functional liver X response element. These data define the chicken FASN gene as a direct target of LXRalpha and further expand the role of LXRalpha as a regulator of lipid metabolism in this species.

  5. Enhancement of caffeic acid phenethyl ester on all-trans retinoic acid-induced differentiation in human leukemia HL-60 cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kuo, H.-C.; Kuo, W.-H.; Lee, Y.-J.

    2006-10-01

    All-trans retinoic acid (ATRA) induces complete remission in a high proportion of patients with acute promyelocytic leukemia (APL); however, the response is sometimes very slow. Furthermore, relapse and resistance to treatment often occur despite continued treatment with ATRA. Thereafter, combination treatment strategies have been suggested to circumvent these problems. The present study demonstrates that caffeic acid phenethyl ester (CAPE), a major component of honeybee propolis, enhanced ATRA-induced granulocytic differentiation in HL-60, a human promyelocytic cell line. The differentiation was assessed by Wright-Giemsa stain, nitroblue tetrazolium reduction, and membrane differentiation marker CD11b. In addition, CAPE enhanced ATRA-induced cell cycle arrest atmore » the G1 phase by decreasing the association of cdk2-cyclin E complex. Finally, it was demonstrated that CAPE promoted the ATRA-mediated nuclear transcription activation of RAR{alpha} assessed by EMSA assay and enhanced the expression of target genes including RAR{alpha}, C/EBP{epsilon}, and p21 protein resulting in the differentiation development of leukemia. It is suggested that CAPE possesses the potential to enhance the efficiency of ATRA in the differentiation therapy of APL.« less

  6. Sertoli cell specific knockdown of RAR-related orphan receptor (ROR) alpha at puberty reduces sperm count in rats.

    PubMed

    Mandal, Kamal; Sarkar, Rajesh K; Sen Sharma, Souvik; Jain, Ayushi; Majumdar, Subeer S

    2018-01-30

    Globally, there is an alarming decline in sperm count. Very often hormonal supplementation fails to restore normal sperm count. Sertoli cells (Sc) present within seminiferous tubules provide appropriate niche and factors required for the differentiation of germ cells (Gc) into mature sperm (spermatogenesis). Functionally compromised Sc may be one of the reasons for failure of hormones to facilitate normal spermatogenesis. Although role of secretory proteins and signaling molecules of Sc has been studied well, role of transcription factors regulating sperm count has not been addressed appropriately. Retinoic acid receptor-related orphan receptor (ROR)-alpha is one of such transcription factors reported in testis but its role in testicular function is not yet known. In a separate study, we found abundant ROR-alpha binding sites on promoter regions of several genes upregulated in pubertal rat Sc as compared to infant Sc. Immunostaining studies also revealed presence of ROR alpha in nucleus of pubertal Sc. We generated a transgenic knockdown rat model expressing shRNA targeted to ROR-alpha under Sc specific promoter, which is transcriptionally active only at and after puberty. ROR-alpha knockdown animals were found to have abnormal association of Sc and Gc, including Gc sloughing and restricted release of sperm. The knockdown animals displayed compromised spermatogenesis leading to significant reduction in sperm count. This is the first report describing the Sc specific role of ROR-alpha in maintaining quantitatively normal sperm output. Identification of various such molecules can generate avenues to limit or reverse an alarmingly declining sperm count witnessed globally in men. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Nuclear retinoid receptors and pregnancy: placental transfer, functions, and pharmacological aspects.

    PubMed

    Comptour, Aurélie; Rouzaire, Marion; Belville, Corinne; Bouvier, Damien; Gallot, Denis; Blanchon, Loïc; Sapin, Vincent

    2016-10-01

    Animal models of vitamin A (retinol) deficiency have highlighted its crucial role in reproduction and placentation, whereas an excess of retinoids (structurally or functionally related entities) can cause toxic and teratogenic effects in the embryo and foetus, especially in the first trimester of human pregnancy. Knock-out experimental strategies-targeting retinoid nuclear receptors RARs and RXRs have confirmed that the effects of vitamin A are mediated by retinoic acid (especially all-trans retinoic acid) and that this vitamin is essential for the developmental process. All these data show that the vitamin A pathway and metabolism are as important for the well-being of the foetus, as they are for that of the adult. Accordingly, during this last decade, extensive research on retinoid metabolism has yielded detailed knowledge on all the actors in this pathway, spurring the development of antagonists and agonists for therapeutic and research applications. Natural and synthetic retinoids are currently used in clinical practice, most often on the skin for the treatment of acne, and as anti-oncogenic agents in acute promyelocytic leukaemia. However, because of the toxicity and teratogenicity of retinoids during pregnancy, their pharmacological use needs a sound knowledge of their metabolism, molecular aspects, placental transfer, and action.

  8. Autonomous rexinoid death signaling is suppressed by converging signaling pathways in immature leukemia cells.

    PubMed

    Benoit, G R; Flexor, M; Besançon, F; Altucci, L; Rossin, A; Hillion, J; Balajthy, Z; Legres, L; Ségal-Bendirdjian, E; Gronemeyer, H; Lanotte, M

    2001-07-01

    On their own, retinoid X receptor (RXR)-selective ligands (rexinoids) are silent in retinoic acid receptor (RAR)-RXR heterodimers, and no selective rexinoid program has been described as yet in cellular systems. We report here on the rexinoid signaling capacity that triggers apoptosis of immature promyelocytic NB4 cells as a default pathway in the absence of survival factors. Rexinoid-induced apoptosis displays all features of bona fide programmed cell death and is inhibited by RXR, but not RAR antagonists. Several types of survival signals block rexinoid-induced apoptosis. RARalpha agonists switch the cellular response toward differentiation and induce the expression of antiapoptosis factors. Activation of the protein kinase A pathway in the presence of rexinoid agonists induces maturation and blocks immature cell apoptosis. Addition of nonretinoid serum factors also blocks cell death but does not induce cell differentiation. Rexinoid-induced apoptosis is linked to neither the presence nor stability of the promyelocytic leukemia-RARalpha fusion protein and operates also in non-acute promyelocytic leukemia cells. Together our results support a model according to which rexinoids activate in certain leukemia cells a default death pathway onto which several other signaling paradigms converge. This pathway is entirely distinct from that triggered by RAR agonists, which control cell maturation and postmaturation apoptosis.

  9. Retinoids, retinoid analogs, and lactoferrin interact and differentially affect cell viability of 2 bovine mammary cell types in vitro.

    PubMed

    Wang, Y; Baumrucker, C R

    2010-07-01

    Two bovine mammary cell types (BME-UV1 and MeBo cells) were used to evaluate the effect of natural retinoids, retinoid analogs, and bovine lactoferrin (bLf) on cell viability in vitro. Experiments with Alamar Blue showed a linear relationship between fluorescence and cell viability index. The BME-UV1 cells exhibited twice the metabolic activity but required half the doubling time of the MeBo cells. The BME-UV1 cells were very sensitive to all-trans retinoic acid (atRA) inhibition of cell viability (P<0.05) and exhibited a dose-dependent inhibition with 9-cisRA (9cRA; P<0.05). The MeBo cells exhibited some inhibition with these natural ligands (P<0.05), but they were not as sensitive. The addition of bLf had similar inhibitory effects (P<0.05) on cell viability of the 2 mammary cell types. Applications of RA receptor (RAR) agonist indicated that the stimulation of the RAR in both mammary cell types was highly effective in inhibition of cell viability (P<0.05), whereas the application of an RAR antagonist stimulated MeBo cell viability (P<0.05) and inhibited BME-UV1 cell viability (P<0.05). Finally, the use of the RAR antagonist in conjunction with bLf indicated a rescue of the bLf effect in the MeBo cells, suggesting that bLf is acting through the RAR receptor. Conversely, bLf reverted inhibition of cell viability by 9cRA in the BME-UV1 cell type (P<0.05). We conclude that RAR interaction in bovine mammary cell types regulates cell viability in vitro; we hypothesize that the natural ligands mediate regulation of bovine mammary cell viability in vivo and that bLf can either enhance or reverse the retinoid-induced inhibition of cell viability, depending on the type of bovine mammary cell studied.

  10. Water-Soluble Nanoparticle Receptors Supramolecularly Coded for Acidic Peptides.

    PubMed

    Fa, Shixin; Zhao, Yan

    2018-01-02

    Sequence-specific recognition of peptides is of enormous importance to many chemical and biological applications, but has been difficult to achieve due to the minute differences in the side chains of amino acids. Acidic peptides are known to play important roles in cell growth and gene expression. In this work, we report molecularly imprinted micelles coded with molecular recognition information for the acidic and hydrophobic side chains of acidic peptides. The imprinted receptors could distinguish acidic amino acids from other polar and nonpolar amino acids, with dissociation constants of tens of nanomolar for biologically active peptides containing up to 18 amino acids. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Kinetic properties of the human liver cytosolic aldehyde dehydrogenase for retinal isomers.

    PubMed

    Bhat, P V; Samaha, H

    1999-01-15

    Retinoic acid exerts pleiotropic effects by acting through two families of nuclear receptors, RAR and RXR. All-trans and 9-cis retinoic acid bind RARs, whereas 9-cis retinoic acid binds and activates only the RXRs. To understand the role of human liver cytosolic aldehyde dehydrogenase (ALDH1) in retinoic acid synthesis, we examined the ability of ALDH 1 to catalyze the oxidation of the naturally occurring retinal isomers. ALDH1 catalyzed the oxidation of all-trans, 9-cis, and 13-cis retinal with equal efficiency. However, the affinity to all-trans retinal (Km = 2.2 microM) was twofold higher than to 9-cis (Km = 5.5 microM) and 13-cis (Km = 4.6 microM) retinal. All-trans retinol was a potent inhibitor of ALDH1 activity, and inhibited all-trans retinal oxidation uncompetitively. Comparison of the kinetic properties of ALDH1 for retinal isomers with those of previously reported rat kidney retinal dehydrogenase showed distinct differences, suggesting that ALDH1 may play a different role in retinal metabolism in liver.

  12. Pulmonary stretch receptor afferents activate excitatory amino acid receptors in the nucleus tractus solitarii in rats.

    PubMed

    Bonham, A C; Coles, S K; McCrimmon, D R

    1993-05-01

    1. The goal of the present study was to identify potential neurotransmitter candidates in the Breuer-Hering (BH) reflex pathway, specifically at synapses between the primary afferents and probable second-order neurones (pump cells) within the nucleus tractus solitarii (NTS). We hypothesized that if activation of specific receptors in the NTS is required for production of the BH reflex, then (1) injection of the receptor agonist(s) would mimic the reflex response (apnoea), (2) injection of appropriate antagonists would impair the apnoea produced by either lung inflation or agonist injection, and (3) second-order neurones in the pathway would be excited by either lung inflation or agonists while antagonists would prevent the response to either. 2. Studies were carried out either in spontaneously breathing or in paralysed, thoracotomized and ventilated rats in which either diaphragm EMG or phrenic nerve activity, expired CO2 concentration and arterial pressure were continuously monitored. The BH reflex was physiologically activated by inflating the lungs. 3. Pressure injections (0.03-15 pmol) of selective excitatory amino acid (EAA) receptor agonists, quisqualic acid (Quis) and N-methyl-D-aspartic acid (NMDA) into an area of the NTS shown previously to contain neurones required for production of the BH reflex produced dose-dependent apnoeas that mimicked the response to lung inflation. Injection of substance P (0.03-4 pmol) did not alter baseline respiratory pattern. 4. Injections of the EAA antagonists, kynurenic acid (Kyn; 0.6-240 pmol), 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX) or 6,7-dinitroquinoxaline-2,3-dione (DNQX) into the BH region of the NTS reversibly impaired the apnoea produced by lung inflation. All three antagonists reduced or abolished the apnoeas resulting from injection of Quis or NMDA, and slowed baseline respiratory frequency. In contrast, injections of the highly selective NMDA receptor antagonist, D-2-amino-5-phosphonovaleric acids (AP5), in

  13. 9-Cis-Retinoic Acid Induces Growth Inhibition in Retinoid-Sensitive Breast Cancer and Sea Urchin Embryonic Cells via Retinoid X Receptor α and Replication Factor C3

    PubMed Central

    Maeng, Sejung; Kim, Gil Jung; Choi, Eun Ju; Yang, Hyun Ok; Lee, Dong-Sup

    2012-01-01

    There is widespread interest in defining factors and mechanisms that suppress the proliferation of cancer cells. Retinoic acid (RA) is a potent suppressor of mammary cancer and developmental embryonic cell proliferation. However, the molecular mechanisms by which 9-cis-RA signaling induces growth inhibition in RA-sensitive breast cancer and embryonic cells are not apparent. Here, we provide evidence that the inhibitory effect of 9-cis-RA on cell proliferation depends on 9-cis-RA-dependent interaction of retinoid X receptor α (RXRα) with replication factor C3 (RFC3), which is a subunit of the RFC heteropentamer that opens and closes the circular proliferating cell nuclear antigen (PCNA) clamp on DNA. An RFC3 ortholog in a sea urchin cDNA library was isolated by using the ligand-binding domain of RXRα as bait in a yeast two-hybrid screening. The interaction of RFC3 with RXRα depends on 9-cis-RA and bexarotene, but not on all-trans-RA or an RA receptor (RAR)-selective ligand. Truncation and mutagenesis experiments demonstrated that the C-terminal LXXLL motifs in both human and sea urchin RFC3 are critical for the interaction with RXRα. The transient interaction between 9-cis-RA-activated RXRα and RFC3 resulted in reconfiguration of the PCNA-RFC complex. Furthermore, we found that knockdown of RXRα or overexpression of RFC3 impairs the ability of 9-cis-RA to inhibit proliferation of MCF-7 breast cancer cells and sea urchin embryogenesis. Our results indicate that 9-cis-RA-activated RXRα suppresses the growth of RA-sensitive breast cancer and embryonic cells through RFC3. PMID:22949521

  14. Synthesis and biological evaluation of 2-heteroarylthioalkanoic acid analogues of clofibric acid as peroxisome proliferator-activated receptor alpha agonists.

    PubMed

    Giampietro, Letizia; Ammazzalorso, Alessandra; Giancristofaro, Antonella; Lannutti, Fabio; Bettoni, Giancarlo; De Filippis, Barbara; Fantacuzzi, Marialuigia; Maccallini, Cristina; Petruzzelli, Michele; Morgano, Annalisa; Moschetta, Antonio; Amoroso, Rosa

    2009-10-22

    A series of 2-heteroarylthioalkanoic acids were synthesized through systematic structural modifications of clofibric acid and evaluated for human peroxisome proliferator-activated receptor alpha (PPARalpha) transactivation activity, with the aim of obtaining new hypolipidemic compounds. Some thiophene and benzothiazole derivatives showing a good activation of the receptor alpha were screened for activity against the PPARgamma isoform. The gene induction of selected compounds was also investigated in the human hepatoma cell line.

  15. Nicotinic Acid Receptor Abnormalities in Human Skin Cancer: Implications for a Role in Epidermal Differentiation

    PubMed Central

    Bermudez, Yira; Benavente, Claudia A.; Meyer, Ralph G.; Coyle, W. Russell; Jacobson, Myron K.; Jacobson, Elaine L.

    2011-01-01

    Background Chronic UV skin exposure leads to epidermal differentiation defects in humans that can be largely restored by pharmacological doses of nicotinic acid. Nicotinic acid has been identified as a ligand for the human G-protein-coupled receptors GPR109A and GPR109B that signal through Gi-mediated inhibition of adenylyl cyclase. We have examined the expression, cellular distribution, and functionality of GPR109A/B in human skin and skin derived epidermal cells. Results Nicotinic acid increases epidermal differentiation in photodamaged human skin as judged by the terminal differentiation markers caspase 14 and filaggrin. Both GPR109A and GPR109B genes are transcribed in human skin and in epidermal keratinocytes, but expression in dermal fibroblasts is below limits of detection. Receptor transcripts are greatly over-expressed in squamous cell cancers. Receptor protein in normal skin is prominent from the basal through granular layers of the epidermis, with cellular localization more dispersive in the basal layer but predominantly localized at the plasma membrane in more differentiated epidermal layers. In normal human primary and immortalized keratinocytes, nicotinic acid receptors show plasma membrane localization and functional Gi-mediated signaling. In contrast, in a squamous cell carcinoma derived cell line, receptor protein shows a more diffuse cellular localization and the receptors are nearly non-functional. Conclusions The results of these studies justify future genetic and pharmacological intervention studies to define possible specific role(s) of nicotinic acid receptors in human skin homeostasis. PMID:21655214

  16. Inhibition of proliferation and induction of apoptosis in soft tissue sarcoma cells by interferon-α and retinoids

    PubMed Central

    Brodowicz, T; Wiltschke, C; Kandioler-Eckersberger, D; Grunt, T W; Rudas, M; Schneider, S M; Hejna, M; Budinsky, A; Zielinski, C C

    1999-01-01

    Uncontrolled proliferation and a defect of apoptosis constitute crucial elements in the development and progression of tumours. Among many other biological response modifiers known to influence these mechanisms, the efficacy of retinoids and interferons in the treatment of various malignant entities is currently matter of discussion. In the present study, we have investigated the effects of 9-cis-retinoic acid (9cRA), 13-cis-retinoic acid (13cRA), all-trans-retinoic acid (tRA) and interferon-α on proliferation and apoptosis of human soft tissue sarcoma (STS) cell lines HTB-82 (rhabdomyosarcoma), HTB-91 (fibrosarcoma), HTB-92 (liposarcoma), HTB-93 (synovial sarcoma) and HTB-94 (chondrosarcoma) in relation to p53 genotype as well as p53 expression. HTB-91, HTB-92 and HTB-94 STS cells exhibited mutant p53, whereas wild-type p53 was found in HTB-93 STS cells, and a normal p53 status in HTB-82 STS cells, carrying a silent point mutation only. Interferon-α, irrespective of p53 status, inhibited the proliferation of all five cell lines dose- and time-dependently. Similarly, 9cRA, 13cRA and tRA decreased the proliferation of HTB-82 and HTB-93 STS cells, whereas the proliferation of p53-mutated HTB-91, HTB-92 and HTB-94 STS cells remained unchanged. Furthermore, only 9cRA and tRA were capable of inducing apoptosis in HTB-82 and HTB-93 STS cells, whereas HTB-91, HTB-92 and HTB-94 STS cells did not undergo apoptosis under the influence of 9cRA or tRA. Retinoic acid receptor (RAR)-α and RAR-β mRNA were not detectable by Northern blot analysis in the five STS cell lines, whereas mRNA for the universal retinoic acid receptor, RAR-γ, was expressed in all STS cell lines indicating that retinoid resistance was not associated with a lack of RAR expression. Apoptosis was not induced by interferon-α or 13cRA in any of the five STS cell lines tested. Our results indicate that within the panel of tested STS cell lines, inhibition of proliferation and induction of apoptosis result

  17. Endocytosis of lysosomal acid phosphatase; involvement of mannose receptor and effect of lectins.

    PubMed

    Imai, K; Yoshimura, T

    1994-08-01

    Acid phosphatase and beta-glucosidase are unique among lysosomal enzymes in that they have both high mannose and complex type sugasr chains, whereas oligosaccharide chains of lysosomal enzymes in matrix are of high mannose type. We have previously shown that beta-glucosidase was endocytosed into macrophages via an unidentified receptor different from a mannose/fucose receptor (K. Imai, Cell Struct. Funct. 13, 325-332, 1988). Here, we show that uptake of acid phosphatase purified from rat liver lysosomes into rat macrophages was inhibited by ligands for a mannose/fucose receptor and was mediated via an apparently single binding site with Kuptake of 24.7 nM. These results indicate that acid phosphatase and beta-glucosidase recognize different types of receptors even if they have similar sugar chains. Polyvalent concanavalin A which binds both to the enzyme and to macrophages specifically stimulated the uptake in a dose dependent manner, whereas wheat germ agglutinin and phytohaemagglutinin did not.

  18. Retinoid Expression in Onchocercal Skin Disease: Pilot Study

    PubMed Central

    Mawson, Anthony R; Makunde, Williams H; Penman, Alan D; Hernandez Morales, Veronica de Los Angeles; Kalinga, Akili K; Francis, Filbert; Rubinchik, Semyon; Kibweja, Addow

    2017-01-01

    Based on the observation that the parasite Onchocerca volvulus selectively absorbs vitamin A from the host, and the known toxicity of vitamin A in higher concentration, it was hypothesized that dying microfilariae (mf) release their stores of vitamin A (retinoids) into the host circulation in toxic concentrations, inducing the signs and symptoms of onchocerciasis. We conducted a pilot study to test the hypothesis in Songea communities in Southern Tanzania, where mass drug administration with ivermectin had not been implemented by the time of the survey. The specific aim was to evaluate the correlation between the diagnosis of onchocerciasis and increased levels of retinoic acid at infection sites. The analysis was performed by determining copy numbers of a genome of O volvulus present in skin snip samples of persons with onchocerciacis, and correlating these numbers with expression levels of retinoic acid receptor-α (RAR-α), which is inducible by retinoic acid. Total DNA and RNA were extracted from each of 25 mf-positive and 25 mf-negative skin samples and evaluated using quantitative polymerase chain reaction with appropriate negative controls. Analysis of the samples, adjusted with glyceraldehyde 3-phosphate dehydrogenase gene levels, revealed that most samples with detectable RAR-α transcripts had higher levels of RAR-α expression than the assay control. However, the quality and number of samples were insufficient for statistical analysis. Fold data on the expression levels of both O volvulus DNA and RAR RNA suggested a possible trend toward higher relative RAR-α expression in samples with higher levels of O volvulus DNA (r2 = 0.25, P = .079). Evidence of a contribution of vitamin A to the pathology of onchocerciasis thus remains elusive. Future studies on the role of retinoids in onchocerciasis will require larger groups of participants as well as careful monitoring of the cold chain and tissue storage procedures in view of the sensitivity of

  19. Retinoid Expression in Onchocercal Skin Disease: Pilot Study.

    PubMed

    Mawson, Anthony R; Makunde, Williams H; Penman, Alan D; Hernandez Morales, Veronica de Los Angeles; Kalinga, Akili K; Francis, Filbert; Rubinchik, Semyon; Kibweja, Addow

    2017-01-01

    Based on the observation that the parasite Onchocerca volvulus selectively absorbs vitamin A from the host, and the known toxicity of vitamin A in higher concentration, it was hypothesized that dying microfilariae (mf) release their stores of vitamin A (retinoids) into the host circulation in toxic concentrations, inducing the signs and symptoms of onchocerciasis. We conducted a pilot study to test the hypothesis in Songea communities in Southern Tanzania, where mass drug administration with ivermectin had not been implemented by the time of the survey. The specific aim was to evaluate the correlation between the diagnosis of onchocerciasis and increased levels of retinoic acid at infection sites. The analysis was performed by determining copy numbers of a genome of O volvulus present in skin snip samples of persons with onchocerciacis, and correlating these numbers with expression levels of retinoic acid receptor-α (RAR-α), which is inducible by retinoic acid. Total DNA and RNA were extracted from each of 25 mf-positive and 25 mf-negative skin samples and evaluated using quantitative polymerase chain reaction with appropriate negative controls. Analysis of the samples, adjusted with glyceraldehyde 3-phosphate dehydrogenase gene levels, revealed that most samples with detectable RAR-α transcripts had higher levels of RAR-α expression than the assay control. However, the quality and number of samples were insufficient for statistical analysis. Fold data on the expression levels of both O volvulus DNA and RAR RNA suggested a possible trend toward higher relative RAR-α expression in samples with higher levels of O volvulus DNA ( r 2  = 0.25, P  = .079). Evidence of a contribution of vitamin A to the pathology of onchocerciasis thus remains elusive. Future studies on the role of retinoids in onchocerciasis will require larger groups of participants as well as careful monitoring of the cold chain and tissue storage procedures in view of the sensitivity of

  20. A retinoic acid response element that overlaps an estrogen response element mediates multihormonal sensitivity in transcriptional activation of the lactoferrin gene.

    PubMed

    Lee, M O; Liu, Y; Zhang, X K

    1995-08-01

    The lactoferrin gene is highly expressed in many different tissues, and its expression is controlled by different regulators. In this report, we have defined a retinoic acid response element (RARE) in the 5'-flanking region of the lactoferrin gene promoter. The lactoferrin-RARE is composed of two AGGTCA-like motifs arranged as a direct repeat with 1-bp spacing (DR-1). A gel retardation assay demonstrated that it bound strongly with retinoid X receptor (RXR) homodimers and RXR-retinoic acid receptor (RAR) heterodimers as well as chicken ovalbumin upstream promoter transcription factor (COUP-TF) orphan receptor. In CV-1 cells, the lactoferrin-RARE linked with a heterologous thymidine kinase promoter was strongly activated by RXR homodimers in response to 9-cis-retinoic acid (9-cis-RA) but not to all-trans-RA. When the COUP-TF orphan receptor was cotransfected, the 9-cis-RA-induced RXR homodimer activity was strongly repressed. A unique feature of the lactoferrin-RARE is that it has an AGGTCA-like motif in common with an estrogen-responsive element (ERE). The composite RARE/ERE contributes to the functional interaction between retinoid receptors and the estrogen receptor (ER) and their ligands. In CV-1 cells, cotransfection of the retinoid and estrogen receptors led to mutual inhibition of the other's activity, while an RA-dependent inhibition of ER activity was observed in breast cancer cells. Furthermore, the lactoferrin-RARE/ERE showed differential transactivation activity in different cell types. RAs could activate the lactoferrin-RARE/ERE in human leukemia HL-60 cells and U937 cells but not in human breast cancer cells. By gel retardation analyses, we demonstrated that strong binding of the endogenous COUP-TF in breast cancer cells to the composite element contributed to diminished RA response in these cells. Thus, the lactoferrin-RARE/ERE functions as a signaling switch module that mediates multihormonal responsiveness in the regulation of lactoferrin gene

  1. Cross-correlation between vagal afferent impulses from pulmonary mechanoreceptors and high-frequency inflation (HFI) and deflation (HFD) in rabbits.

    PubMed

    Homma, I; Isobe, A; Iwase, M; Onimaru, H; Sibuya, M

    1987-04-10

    The effects of high-frequency airway inflation (HFI) and high-frequency airway deflation (HFD) generated by a triangular pressure pulse generator on pulmonary mechanoreceptors were examined. The cross-correlograms between vagal afferent impulses from the slowly adapting (SAR) and the rapidly adapting receptors (RAR) and the HFI or the HFD pulses were analysed. HFI stimulated SAR and RAR and HFD stimulated RAR, but inhibited SAR. The time lag of the mode in the correlogram between SAR and HFI was shorter than that of the mode in the correlogram between RAR and HFI. The span of the mode and the trough of SAR was shorter than the span of the mode of RAR. This may indicate that the time to peak of the generator potential of RAR is longer than that of SAR.

  2. Farnesoid X receptor induces Takeda G-protein receptor 5 cross-talk to regulate bile acid synthesis and hepatic metabolism.

    PubMed

    Pathak, Preeti; Liu, Hailiang; Boehme, Shannon; Xie, Cen; Krausz, Kristopher W; Gonzalez, Frank; Chiang, John Y L

    2017-06-30

    The bile acid-activated receptors, nuclear farnesoid X receptor (FXR) and the membrane Takeda G-protein receptor 5 (TGR5), are known to improve glucose and insulin sensitivity in obese and diabetic mice. However, the metabolic roles of these two receptors and the underlying mechanisms are incompletely understood. Here, we studied the effects of the dual FXR and TGR5 agonist INT-767 on hepatic bile acid synthesis and intestinal secretion of glucagon-like peptide-1 (GLP-1) in wild-type, Fxr -/- , and Tgr5 -/- mice. INT-767 efficaciously stimulated intracellular Ca 2+ levels, cAMP activity, and GLP-1 secretion and improved glucose and lipid metabolism more than did the FXR-selective obeticholic acid and TGR5-selective INT-777 agonists. Interestingly, INT-767 reduced expression of the genes in the classic bile acid synthesis pathway but induced those in the alternative pathway, which is consistent with decreased taurocholic acid and increased tauromuricholic acids in bile. Furthermore, FXR activation induced expression of FXR target genes, including fibroblast growth factor 15, and unexpectedly Tgr5 and prohormone convertase 1/3 gene expression in the ileum. We identified an FXR-responsive element on the Tgr5 gene promoter. Fxr -/- and Tgr5 -/- mice exhibited reduced GLP-1 secretion, which was stimulated by INT-767 in the Tgr5 -/- mice but not in the Fxr -/- mice. Our findings uncovered a novel mechanism in which INT-767 activation of FXR induces Tgr5 gene expression and increases Ca 2+ levels and cAMP activity to stimulate GLP-1 secretion and improve hepatic glucose and lipid metabolism in high-fat diet-induced obese mice. Activation of both FXR and TGR5 may therefore represent an effective therapy for managing hepatic steatosis, obesity, and diabetes. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Liver X Receptors Balance Lipid Stores in Hepatic Stellate Cells via Rab18, a Retinoid Responsive Lipid Droplet Protein

    PubMed Central

    O’Mahony, Fiona; Wroblewski, Kevin; O’Byrne, Sheila M.; Jiang, Hongfeng; Clerkin, Kara; Benhammou, Jihane; Blaner, William S.; Beaven, Simon W.

    2014-01-01

    Liver X receptors (LXRs) are determinants of hepatic stellate cell (HSC) activation and liver fibrosis. Freshly isolated HSCs from Lxrαβ−/− mice have increased lipid droplet (LD) size but the functional consequences of this are unknown. Our aim was to determine whether LXRs link cholesterol to retinoid storage in HSCs and how this impacts activation. Primary HSCs from Lxrαβ−/− and wild-type (WT) mice were profiled by gene array during in vitro activation. Lipid content was quantified by HPLC and mass spectroscopy. Primary HSCs were treated with nuclear receptor ligands, transfected with siRNA and plasmid constructs, and analyzed by immunocytochemistry. Lxrαβ−/− HSCs have increased cholesterol and retinyl esters (CEs & REs). The retinoid increase drives intrinsic retinoic acid receptor (RAR) signaling and activation occurs more rapidly in Lxrαβ−/− HSCs. We identify Rab18 as a novel retinoic acid responsive, lipid droplet associated protein that helps mediate stellate cell activation. Rab18 mRNA, protein, and membrane insertion increase during activation. Both Rab18 GTPase activity and isoprenylation are required for stellate cell lipid droplet loss and induction of activation markers. These phenomena are accelerated in the Lxrαβ−/− HSCs, where there is greater retinoic acid flux. Conversely, Rab18 knockdown retards lipid droplet loss in culture and blocks activation, just like the functional mutants. Rab18 is also induced with acute liver injury in vivo. Conclusion Retinoid and cholesterol metabolism are linked in stellate cells by the LD associated protein, Rab18. Retinoid overload helps explain the pro-fibrotic phenotype of Lxrαβ−/− mice and we establish a pivotal role for Rab18 GTPase activity and membrane insertion in wild-type stellate cell activation. Interference with Rab18 may have significant therapeutic benefit in ameliorating liver fibrosis. PMID:25482505

  4. Retinoic acid induces proteasome-dependent degradation of retinoic acid receptor α (RARα) and oncogenic RARα fusion proteins

    PubMed Central

    Zhu, Jun; Gianni, Maurizio; Kopf, Eliezer; Honoré, Nicole; Chelbi-Alix, Mounira; Koken, Marcel; Quignon, Frédérique; Rochette-Egly, Cécile; de Thé, Hugues

    1999-01-01

    Analyzing the pathways by which retinoic acid (RA) induces promyelocytic leukemia/retinoic acid receptor α (PML/RARα) catabolism in acute promyelocytic leukemia (APL), we found that, in addition to caspase-mediated PML/RARα cleavage, RA triggers degradation of both PML/RARα and RARα. Similarly, in non-APL cells, RA directly targeted RARα and RARα fusions to the proteasome degradation pathway. Activation of either RARα or RXRα by specific agonists induced degradation of both proteins. Conversely, a mutation in RARα that abolishes heterodimer formation and DNA binding, blocked both RARα and RXRα degradation. Mutations in the RARα DNA-binding domain or AF-2 transcriptional activation region also impaired RARα catabolism. Hence, our results link transcriptional activation to receptor catabolism and suggest that transcriptional up-regulation of nuclear receptors by their ligands may be a feedback mechanism allowing sustained target-gene activation. PMID:10611294

  5. Concomitant Action of Structural Elements and Receptor Phosphorylation Determines Arrestin-3 Interaction with the Free Fatty Acid Receptor FFA4*

    PubMed Central

    Butcher, Adrian J.; Hudson, Brian D.; Shimpukade, Bharat; Alvarez-Curto, Elisa; Prihandoko, Rudi; Ulven, Trond; Milligan, Graeme; Tobin, Andrew B.

    2014-01-01

    In addition to being nutrients, free fatty acids act as signaling molecules by activating a family of G protein-coupled receptors. Among these is FFA4, previously called GPR120, which responds to medium and long chain fatty acids, including health-promoting ω-3 fatty acids, which have been implicated in the regulation of metabolic and inflammatory responses. Here we show, using mass spectrometry, mutagenesis, and phosphospecific antibodies, that agonist-regulated phosphorylation of the human FFA4 receptor occurred primarily at five residues (Thr347, Thr349, Ser350, Ser357, and Ser360) in the C-terminal tail. Mutation of these residues reduced both the efficacy and potency of ligand-mediated arrestin-3 recruitment as well as affecting recruitment kinetics. Combined mutagenesis of all five of these residues was insufficient to fully abrogate interaction with arrestin-3, but further mutagenesis of negatively charged residues revealed additional structural components for the interaction with arrestin-3 within the C-terminal tail of the receptor. These elements consist of the acidic residues Glu341, Asp348, and Asp355 located close to the phosphorylation sites. Receptor phosphorylation thus operates in concert with structural elements within the C-terminal tail of FFA4 to allow for the recruitment of arrestin-3. Importantly, these mechanisms of arrestin-3 recruitment operate independently from Gq/11 coupling, thereby offering the possibility that ligands showing stimulus bias could be developed that exploit these differential coupling mechanisms. Furthermore, this provides a strategy for the design of biased receptors to probe physiologically relevant signaling. PMID:24817122

  6. Amino acid substitutions in the hormone-binding domain of the human androgen receptor alter the stability of the hormone receptor complex.

    PubMed Central

    Marcelli, M; Zoppi, S; Wilson, C M; Griffin, J E; McPhaul, M J

    1994-01-01

    We have investigated the basis of androgen resistance in seven unrelated individuals with complete testicular feminization or Reifenstein syndrome caused by single amino acid substitutions in the hormone-binding domain of the androgen receptor. Monolayer-binding assays of cultured genital skin fibroblasts demonstrated absent ligand binding, qualitative abnormalities of androgen binding, or a decreased amount of qualitatively normal receptor. The consequences of these mutations were examined by introducing the mutations by site-directed mutagenesis into the androgen receptor cDNA sequence and expressing the mutant cDNAs in mammalian cells. The effects of the amino acid substitutions on the binding of different androgens and on the capacity of the ligand-bound receptors to activate a reporter gene were investigated. Substantial differences were found in the responses of the mutant androgen receptors to incubation with testosterone, 5 alpha-dihydrotestosterone, and mibolerone. In several instances, increased doses of hormone or increased frequency of hormone addition to the incubation medium resulted in normal or near normal activation of a reporter gene by cells expressing the mutant androgen receptors. These studies suggest that the stability of the hormone receptor complex is a major determinant of receptor function in vivo. Images PMID:7929841

  7. Modulation of Fc gamma receptors on I cells and monocytes by 15 hydroperoxyeicosatetranoic acid.

    PubMed

    Goodwin, J S; Gualde, N; Aldigier, J; Rigaud, M; Vanderhoek, J Y

    1984-01-01

    We investigated the effects of the 15-lipoxygenase products, 15 hydroperoxyeicosatetranoic acid (15 HPETE) and 15 hydroxyeicosatetranoic acid (15 HETE) on Fc gamma receptor expression on human T cells and monocytes. Incubation of these cells with 15 HPETE but not 15 HETE results in a shift to decreased density of Fc gamma receptors on the cell surface.

  8. [Basic and clinical studies of the gene product-targeting therapy based on leukemogenesis--editorial].

    PubMed

    Chen, Sai-Juan; Chen, Li-Juan; Zhou, Guang-Biao

    2005-02-01

    In the last twenty years, using all-trans retinoic acid (ATRA) as a differentiation inducer, Shanghai Institute of Hematology has achieved an important breakthrough in the treatment of acute promyelocytic leukemia (APL), which realized the theory of reversing phenotype of cells and provided a successful model of differentiation therapy in cancers. Our group first discovered in the world the variant chromosome translocation t(11;17)(q23;q21) of APL, and cloned the PML-RAR alpha, PLZF-RAR alpha and NPM-RAR alpha fusion genes corresponding to the characterized chromosome translocations t(15;17); t(11;17) and t(5;17) in APL. Moreover, establishment of transgenic mice model of APL proved their effects on leukemogenesis. The ability of ATRA to modify the recruitment of nuclear receptor co-repressor with PML-RAR alpha but not PLZF-RAR alpha caused by the variant chromosome translocation elucidated the therapeutic mechanism of ATRA from the molecular level and provides new insight into transcription-modulating therapy. Since 1994, our group has successfully applied arsenic trioxide (As(2)O(3)) in treating relapsed APL patients, with the complete remission rate of 70% - 80%. The molecular mechanism study revealed that As(2)O(3) exerts a dose-dependent dual effect on APL. Low-dose As(2)O(3) induced partial differentiation of APL cells, while the higher dose induced apoptosis. As(2)O(3) binds ubiquitin like SUMO-1 through the lysine 160 of PML, resulting in the degradation of PML-RAR alpha. Taken together, ATRA and As(2)O(3) target the transcription factor PML-RAR alpha, the former by retinoic acid receptor and the latter by PML sumolization, both induce PML-RAR alpha degradation and APL cells differentiation and apoptosis. Because of the different acting pathways, ATRA and As(2)O(3) have no cross-resistance and can be used as combination therapy. Clinical trial in newly diagnosed APL patients showed that ATRA/As(2)O(3) in combination yields a longer disease-free survival

  9. Modulation of GABA receptors expressed in Xenopus oocytes by 13-L-hydroxylinoleic acid and food additives.

    PubMed

    Aoshima, H; Tenpaku, Y

    1997-12-01

    To study the effects of 13-L-hydroxylinoleic acid (LOH) and food additives on gamma-aminobutyric acid (GABA) receptors, ionotropic GABA receptors were expressed in Xenopus oocytes by injecting mRNAs prepared from rat whole brain. LOH, which was prepared by reduction of 13-L-hydroperoxylinoleic acid (LOOH), inhibited the response of GABA receptors in the presence of high concentrations of GABA. LOH also inhibited nicotinic acetylcholine, glycine, and kainate receptors, while it had little effect on NMDA receptors expressed in Xenopus oocytes. However, LOH potentiated the response of GABA receptors as well as LOOH in the presence of low concentrations of GABA, possibly increasing the affinity of GABA for the receptors, while linoleic acid did not. Since some modification of the compounds seemed to change their effects on GABA receptors, the responses of GABA receptors elicited by 10 microM GABA were measured in the presence of compounds with various kinds of functional groups or the structural isomers of pentanol. Potentiation of GABA receptors depended strongly on the species of functional groups and also depended on the structure of the isomers. Then effects of various kinds of food additives on GABA receptors were also examined; perfumes such as alcohols or esters potentiated the responses strongly, while hexylamine, nicotinamide, or caffeine inhibited the responses, mainly in a competitive manner, and vanillin inhibited the responses noncompetitively. These results suggest the possibility that production of LOOH and LOH, or intake of much of some food additives, modulates the neural transmission in the brain, especially through ionotropic GABA receptors and changes the frame of the human mind, as alcohol or tobacco does.

  10. Morphology of presumptive rapidly adapting receptors in the rat bronchus.

    PubMed Central

    Kappagoda, C T; Skepper, J N; McNaughton, L; Siew, E E; Navaratnam, V

    1990-01-01

    The present investigation was undertaken in rats to determine whether sensory nerves exist in apposition to the bronchial microvessels which may function as rapidly adapting receptors (RAR). The primary and secondary bronchi on both sides were removed and processed for light and electron microscopy. Nerves were frequently found in relation to venules external to the muscle coat of bronchi. They comprised myelinated axons which ended individually as non-myelinated convoluted terminals enclosed within a loose capsule of attenuated cells. Serial sections showed that these terminals were not related to ganglion cells. Cervical vagal section and injection of HRP-WGA into the nodose ganglion provided corroborative evidence of the sensory nature of these terminals. Vagal section caused degenerative changes in the encapsulated nerve terminals in the bronchial walls and horseradish peroxidase labelling was demonstrable in such terminals. Moreover, immunocytochemical studies demonstrated the presence of calcitonin gene regulated peptide and substance P in these structures. It is suggested that they comprise the RAR. Encapsulated nerve terminals were not found in the epithelial layer, in the submucous coat or in the muscularis of bronchi. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 PMID:1691164

  11. Invited review: nutrient-sensing receptors for free fatty acids and hydroxycarboxylic acids in farm animals.

    PubMed

    Mielenz, M

    2017-06-01

    Data on nutrient sensing by free fatty acid receptors (FFAR1, FFAR2, FFAR3, FFAR4) and hydroxycarboxylic acid receptors (HCAR1, HCAR2) are increasing for human or rodent models. Both receptor families link intestinal fermentation by the microbiota and energy metabolism with cellular responses. Therefore, this finding provides a link that is independent of the only function of the fermentation products as energy substrates. For example, these reactions are associated with insulin secretion, regulation of lipolysis, adipose tissue differentiation and innate immune responses. In farm animals, the available data on both receptor families from the intestine and other tissues increase. However, currently, the data are primarily linked with the distribution of receptor messenger RNAs (mRNAs) and more rarely with proteins. Functional data on the importance of these receptors in farm animal species is not abundant and is often associated with the immune system. In certain farm animal species, the receptors were cloned and ligand binding was characterised. In chicken, only one FFAR2 was recently identified using genome analysis, which is contradictory to a study using an FFAR1 small interfering RNA. The chicken FFAR2 is composed of more than 20 paralogs. No data on HCAR1 or HCAR2 exist in this species. Currently, in pigs, most available data are on the mRNA distribution within intestine. However, no FFAR1 expression has been shown in this organ to date. In addition to FFAR2, an orthologue (FFAR2-like) with the highest abundance in intestine has been reported. The data on HCAR1 and HCAR2 in pigs is scarce. In ruminants, most of the currently available information on receptor distribution is linked to mRNA data and shows the expression, for example, in mammary gland and adipose tissue. However, some protein data on FFAR2 and FFAR1 protein has been reported and functional data availability is slowly increasing. The receptor mRNAs of HCAR1 and HCAR2 are expressed in bovine. The

  12. Nutritional Signaling via Free Fatty Acid Receptors

    PubMed Central

    Miyamoto, Junki; Hasegawa, Sae; Kasubuchi, Mayu; Ichimura, Atsuhiko; Nakajima, Akira; Kimura, Ikuo

    2016-01-01

    Excess energy is stored primarily as triglycerides, which are mobilized when demand for energy arises. Dysfunction of energy balance by excess food intake leads to metabolic diseases, such as obesity and diabetes. Free fatty acids (FFAs) provided by dietary fat are not only important nutrients, but also contribute key physiological functions via FFA receptor (FFAR)-mediated signaling molecules, which depend on FFAs’ carbon chain length and the ligand specificity of the receptors. Functional analyses have revealed that FFARs are critical for metabolic functions, such as peptide hormone secretion and inflammation, and contribute to energy homeostasis. In particular, recent studies have shown that the administration of selective agonists of G protein-coupled receptor (GPR) 40 and GPR120 improved glucose metabolism and systemic metabolic disorders. Furthermore, the anti-inflammation and energy metabolism effects of short chain FAs have been linked to the activation of GPR41 and GPR43. In this review, we summarize recent progress in research on FFAs and their physiological roles in the regulation of energy metabolism. PMID:27023530

  13. Effects of retinoids and thiazolidinediones on proliferation, insulin release, insulin mRNA, GLUT 2 transporter protein and mRNA of INS-1 cells.

    PubMed

    Blumentrath, J; Neye, H; Verspohl, E J

    2001-09-01

    Both 9-cis-retinoic acid (9cRA) and all-trans-retinoic acid (ATRA) are active metabolites of vitamin A (retinol). There exists an interaction between retinoid receptors and peroxisome proliferator-activated receptors (PPARgamma). To define their functions in an insulin secreting system the effects of ATRA, 9cRA and the PPARgamma agonist rosiglitazone on cell proliferation, insulin release and glucose transporter (GLUT) 2 of INS-1 cells were tested. Retinoic acid receptor (RAR-alpha and -gamma) and retinoid X receptor (RXR-alpha and -beta) proteins are present (immunoblots). Both 9cRA and ATRA inhibit INS-1 cell proliferation ([3H]-thymidine assay) in a concentration dependent manner. Both 9cRA and ATRA increased insulin release, but only ATRA ralsed the GLUT 2 mRNA in a bell-shaped concentration response curve after 48 h. The insulinotropic effect of one compound is not significantly superimposed by the other indicating that the same binding sites are used by 9cRA and ATRA. The acute and chronic effects of the PPARgamma agonist rosiglitazone on insulin release were additionally determined since glitazones act as transcription factors together with RXR agonists. At high concentrations (100 microM) rosiglitazone inhibited glucose (8.3 mM) stimulated insulin secretion (acute experiment over 60 min). Insulin secretion, however, was increased during a 24 h treatment at a concentration of 10 microM and again inhibited at 100 microM. Changes in preproinsulin mRNA expression were not observed. Rosiglitazone (100 microM) increased GLUT 2 mRNA paralleled by an increase of GLUT 2 protein, but only after 24 h of treatment. This data indicate that RAR and RXR mediate insulin release. The changes in GLUT 2 have no direct impact on insulin release; the inhibition seen at high concentrations of either compound is possibly the result of the observed inhibition of cell proliferation. Effects of rosiglitazone on preproinsulin mRNA and GLUT 2 (mRNA and protein) do not play a role in

  14. Concomitant action of structural elements and receptor phosphorylation determines arrestin-3 interaction with the free fatty acid receptor FFA4.

    PubMed

    Butcher, Adrian J; Hudson, Brian D; Shimpukade, Bharat; Alvarez-Curto, Elisa; Prihandoko, Rudi; Ulven, Trond; Milligan, Graeme; Tobin, Andrew B

    2014-06-27

    In addition to being nutrients, free fatty acids act as signaling molecules by activating a family of G protein-coupled receptors. Among these is FFA4, previously called GPR120, which responds to medium and long chain fatty acids, including health-promoting ω-3 fatty acids, which have been implicated in the regulation of metabolic and inflammatory responses. Here we show, using mass spectrometry, mutagenesis, and phosphospecific antibodies, that agonist-regulated phosphorylation of the human FFA4 receptor occurred primarily at five residues (Thr(347), Thr(349), Ser(350), Ser(357), and Ser(360)) in the C-terminal tail. Mutation of these residues reduced both the efficacy and potency of ligand-mediated arrestin-3 recruitment as well as affecting recruitment kinetics. Combined mutagenesis of all five of these residues was insufficient to fully abrogate interaction with arrestin-3, but further mutagenesis of negatively charged residues revealed additional structural components for the interaction with arrestin-3 within the C-terminal tail of the receptor. These elements consist of the acidic residues Glu(341), Asp(348), and Asp(355) located close to the phosphorylation sites. Receptor phosphorylation thus operates in concert with structural elements within the C-terminal tail of FFA4 to allow for the recruitment of arrestin-3. Importantly, these mechanisms of arrestin-3 recruitment operate independently from Gq/11 coupling, thereby offering the possibility that ligands showing stimulus bias could be developed that exploit these differential coupling mechanisms. Furthermore, this provides a strategy for the design of biased receptors to probe physiologically relevant signaling. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Short-chain fatty acid receptors inhibit invasive phenotypes in breast cancer cells

    PubMed Central

    Thirunavukkarasan, Madhumathi; Wang, Chao; Rao, Angad; Hind, Tatsuma; Teo, Yuan Ru; Siddiquee, Abrar Al-Mahmood; Goghari, Mohamed Ally Ibrahim; Kumar, Alan Prem

    2017-01-01

    Short chain fatty acids (2 to 6 carbons in length) are ubiquitous lipids that are present in human plasma at micromolar concentrations. In addition to serving as metabolic precursors for lipid and carbohydrate synthesis, they also act as cognate ligands for two known G protein-coupled receptors (GPCRs), FFAR2 and FFAR3. While there is evidence that these receptors may inhibit the progression of colorectal cancer, their roles in breast cancer cells are largely unknown. We evaluated the effects of enforced overexpression of these receptors in two phenotypically distinct breast cancer cell lines: MCF7 and MDA-MD-231. Our results demonstrate that both receptors inhibit cell invasiveness, but through different signaling processes. In invasive, mesenchymal-like MDA-MB-231 cells, FFAR2 inhibits the Hippo-Yap pathway and increases expression of adhesion protein E-cadherin, while FFAR3 inhibits MAPK signaling. Both receptors have the net effect of reducing actin polymerization and invasion of cells through a Matrigel matrix. These effects were absent in the less invasive, epithelial-like MCF7 cells. Correspondingly, there is reduced expression of both receptors in invasive breast carcinoma and in aggressive triple-negative breast tumors, relative to normal breast tissue. Cumulatively, our data suggest that the activation of cognate receptors by short chain fatty acids drives breast cancer cells toward a non-invasive phenotype and therefore may inhibit metastasis. PMID:29049318

  16. Distinct nuclear body components, PML and SMRT, regulate the trans-acting function of HTLV-1 Tax oncoprotein.

    PubMed

    Ariumi, Yasuo; Ego, Takeshi; Kaida, Atsushi; Matsumoto, Mikiko; Pandolfi, Pier Paolo; Shimotohno, Kunitada

    2003-03-20

    Several viruses target cellular promyelocytic leukemia (PML)-nuclear bodies (PML-NBs) to induce their disruption, marked morphological changes in these structures or the relocation to PML-NB components to the cytoplasm of infected cells. PML conversely interferes with viral replication. We demonstrate that PML acts as a coactivator for the human T-cell leukemia virus type 1 (HTLV-1) Tax oncoprotein without direct binding. Tax was identified within interchromatin granule clusters (IGCs)/RNA splicing bodies (SBs), not PML-NBs; Tax expression did not affect PML-NB formation. Moreover, PML and CBP/p300 cooperatively activated Tax-mediated HTLV-1-LTR-dependent gene expression. Interestingly, two PML mutants, PML-RAR and PMLDelta216-331, which fail to form PML-NBs, could also coactivate Tax-mediated trans-acting function but had no effect on retinoic acid receptor (RAR)- or p53-dependent gene expression. In contrast, SMRT (silencing mediator for retinoic acid and thyroid hormone receptors), a nuclear corepressor found within the matrix-associated deacetylase (MAD) nuclear body, relocalized into Tax-associated nuclear bodies upon coexpression with Tax. SMRT coactivated the trans-acting function of Tax through direct binding. Coexpression of SMRT and PML resulted in an additive activation of Tax trans-acting function. Thus, crosstalk between distinct nuclear bodies may control Tax function.

  17. Ursodeoxycholic Acid Suppresses Lipogenesis in Mouse Liver: Possible Role of the Decrease in β-Muricholic Acid, a Farnesoid X Receptor Antagonist.

    PubMed

    Fujita, Kyosuke; Iguchi, Yusuke; Une, Mizuho; Watanabe, Shiro

    2017-04-01

    The farnesoid X receptor (FXR) is a major nuclear receptor of bile acids; its activation suppresses sterol regulatory element-binding protein 1c (SREBP1c)-mediated lipogenesis and decreases the lipid contents in the liver. There are many reports showing that the administration of ursodeoxycholic acid (UDCA) suppresses lipogenesis and reduces the lipid contents in the liver of experimental animals. Since UDCA is not recognized as an FXR agonist, these effects of UDCA cannot be readily explained by its direct activation of FXR. We observed that the dietary administration of UDCA in mice decreased the expression levels of SREBP1c and its target lipogenic genes. Alpha- and β-muricholic acids (MCA) and cholic acid (CA) were the major bile acids in the mouse liver but their contents decreased upon UDCA administration. The hepatic contents of chenodeoxycholic acid and deoxycholic acid (DCA) were relatively low but were not changed by UDCA. UDCA did not show FXR agonistic or antagonistic potency in in vitro FXR transactivation assay. Taking these together, we deduced that the above-mentioned change in hepatic bile acid composition induced upon UDCA administration might cause the relative increase in the FXR activity in the liver, mainly by the reduction in the content of β-MCA, a farnesoid X receptor antagonist, which suggests a mechanism by which UDCA suppresses lipogenesis and decreases the lipid contents in the mouse liver.

  18. Cyclic mu-opioid receptor ligands containing multiple N-methylated amino acid residues.

    PubMed

    Adamska-Bartłomiejczyk, Anna; Janecka, Anna; Szabó, Márton Richárd; Cerlesi, Maria Camilla; Calo, Girolamo; Kluczyk, Alicja; Tömböly, Csaba; Borics, Attila

    2017-04-15

    In this study we report the in vitro activities of four cyclic opioid peptides with various sequence length/macrocycle size and N-methylamino acid residue content. N-Methylated amino acids were incorporated and cyclization was employed to enhance conformational rigidity to various extent. The effect of such modifications on ligand structure and binding properties were studied. The pentapeptide containing one endocyclic and one exocyclic N-methylated amino acid displayed the highest affinity to the mu-opioid receptor. This peptide was also shown to be a full agonist, while the other analogs failed to activate the mu opioid receptor. Results of molecular docking studies provided rationale for the explanation of binding properties on a structural basis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Organoboron compounds as Lewis acid receptors of fluoride ions in polymeric membranes.

    PubMed

    Jańczyk, Martyna; Adamczyk-Woźniak, Agnieszka; Sporzyński, Andrzej; Wróblewski, Wojciech

    2012-07-06

    Newly synthesized organoboron compounds - 4-octyloxyphenylboronic acid (OPBA) and pinacol ester of 2,4,6-trifluorophenylboronic acid (PE-PBA) - were applied as Lewis acid receptors of fluoride anions. Despite enhanced selectivity, the polymer membrane electrodes containing the lipophilic receptor OPBA exhibited non-Nernstian slopes of the responses toward fluoride ions in acidic conditions. Such behavior was explained by the lability of the B-O bond in the boronic acids, and the OH(-)/F(-) exchange at higher fluoride content in the sample solution. In consequence, the stoichiometry of the OPBA-fluoride complexes in the membrane could vary during the calibration, changing the equilibrium concentration of the primary anion in membrane and providing super-Nernstian responses. The proposed mechanism was supported by (19)F NMR studies, which indicated that the fluoride complexation proceeds more effectively in acidic solution leading mainly to PhBF(3)(-) species. Finally, the performances of the membranes based on the phenylboronic acid pinacol ester, with a more stable B-O bond, were tested. As it was expected, Nernstian fluoride responses were recorded for such membranes with worsened fluoride selectivity. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Enhancement of arachidonic acid signaling pathway by nicotinic acid receptor HM74A

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tang, Yuting; Zhou, Lubing; Gunnet, Joseph W.

    2006-06-23

    HM74A is a G protein-coupled receptor for nicotinic acid (niacin), which has been used clinically to treat dyslipidemia for decades. The molecular mechanisms whereby niacin exerts its pleiotropic effects on lipid metabolism remain largely unknown. In addition, the most common side effect in niacin therapy is skin flushing that is caused by prostaglandin release, suggesting that the phospholipase A{sub 2} (PLA{sub 2})/arachidonic acid (AA) pathway is involved. Various eicosanoids have been shown to activate peroxisome-proliferator activated receptors (PPAR) that play a diverse array of roles in lipid metabolism. To further elucidate the potential roles of HM74A in mediating the therapeuticmore » effects and/or side effects of niacin, we sought to explore the signaling events upon HM74A activation. Here we demonstrated that HM74A synergistically enhanced UTP- and bradykinin-mediated AA release in a pertussis toxin-sensitive manner in A431 cells. Activation of HM74A also led to Ca{sup 2+}-mobilization and enhanced bradykinin-promoted Ca{sup 2+}-mobilization through Gi protein. While HM74A increased ERK1/2 activation by the bradykinin receptor, it had no effects on UTP-promoted ERK1/2 activation.Furthermore, UTP- and bradykinin-mediated AA release was significantly decreased in the presence of both MAPK kinase inhibitor PD 098059 and PKC inhibitor GF 109203X. However, the synergistic effects of HM74A were not dramatically affected by co-treatment with both inhibitors, indicating the cross-talk occurred at the receptor level. Finally, stimulation of A431 cells transiently transfected with PPRE-luciferase with AA significantly induced luciferase activity, mimicking the effects of PPAR{gamma} agonist rosiglitazone, suggesting that alteration of AA signaling pathway can regulate gene expression via endogenous PPARs.« less

  1. Decreased glucagon responsiveness by bile acids: a role for protein kinase Calpha and glucagon receptor phosphorylation.

    PubMed

    Ikegami, Tadashi; Krilov, Lada; Meng, Jianping; Patel, Bhumika; Chapin-Kennedy, Kelli; Bouscarel, Bernard

    2006-11-01

    Dihydroxy bile acids like chenodeoxycholic acid (CDCA) induce heterologous glucagon receptor desensitization. We previously demonstrated that protein kinase C (PKC) was activated by certain bile acids and mediated the CDCA-induced decrease in glucagon responsiveness. The aim of the present study was to explore the role of PKC in the phosphorylation and desensitization of the glucagon receptor by CDCA. Desensitization was evaluated by measuring adenylyl cyclase activity. Receptor phosphorylation was assayed by metabolic labeling with [gamma-(32)P] ATP. Protein kinase C (PKC) translocation and activation was visualized by fluorescence microscopy. CDCA decreased cAMP production induced by glucagon in a dose-dependent manner without affecting cAMP synthesis through stimulation of either stimulatory GTP-binding protein (Gs) by NaF or adenylyl cyclase by forskolin. The CDCA-induced inhibition of adenylyl cyclase activity was potentiated by the phosphatase inhibitor, okadaic acid. The desensitizing effect of CDCA was bile acid-specific and was significantly reduced in the presence of PKC inhibitors and after PKC down-regulation by phorbol 12-myristate 13-acetate. CDCA increased glucagon receptor phosphorylation more than 3-fold at concentrations as low as 25 mum. Furthermore, CDCA significantly stimulated human recombinant PKCalpha autophosphorylation in vitro, as well as PKCalpha translocation to the plasma membrane and phosphorylation in vivo at concentrations as low as 25 mum. CDCA also stimulated PKCdelta translocation to the perinuclear region. Activated PKCalpha, PKCzeta, and to a lesser extent, PKCdelta, phosphorylated the glucagon receptor in vitro. This study demonstrates that certain bile acids, such as CDCA, stimulate phosphorylation and heterologous desensitization of the glucagon receptor, involving at least PKCalpha activation.

  2. Medium-chain fatty acid-sensing receptor, GPR84, is a proinflammatory receptor.

    PubMed

    Suzuki, Masakatsu; Takaishi, Sachiko; Nagasaki, Miyuki; Onozawa, Yoshiko; Iino, Ikue; Maeda, Hiroaki; Komai, Tomoaki; Oda, Tomiichiro

    2013-04-12

    G protein-coupled receptor 84 (GPR84) is a putative receptor for medium-chain fatty acids (MCFAs), whose pathophysiological roles have not yet been clarified. Here, we show that GPR84 was activated by MCFAs with the hydroxyl group at the 2- or 3-position more effectively than nonhydroxylated MCFAs. We also identified a surrogate agonist, 6-n-octylaminouracil (6-OAU), for GPR84. These potential ligands and the surrogate agonist, 6-OAU, stimulated [(35)S]GTP binding and accumulated phosphoinositides in a GPR84-dependent manner. The surrogate agonist, 6-OAU, internalized GPR84-EGFP from the cell surface. Both the potential ligands and 6-OAU elicited chemotaxis of human polymorphonuclear leukocytes (PMNs) and macrophages and amplified LPS-stimulated production of the proinflammatory cytokine IL-8 from PMNs and TNFα from macrophages. Furthermore, the intravenous injection of 6-OAU raised the blood CXCL1 level in rats, and the inoculation of 6-OAU into the rat air pouch accumulated PMNs and macrophages in the site. Our results indicate a proinflammatory role of GPR84, suggesting that the receptor may be a novel target to treat chronic low grade inflammation associated-disease.

  3. Medium-chain Fatty Acid-sensing Receptor, GPR84, Is a Proinflammatory Receptor

    PubMed Central

    Suzuki, Masakatsu; Takaishi, Sachiko; Nagasaki, Miyuki; Onozawa, Yoshiko; Iino, Ikue; Maeda, Hiroaki; Komai, Tomoaki; Oda, Tomiichiro

    2013-01-01

    G protein-coupled receptor 84 (GPR84) is a putative receptor for medium-chain fatty acids (MCFAs), whose pathophysiological roles have not yet been clarified. Here, we show that GPR84 was activated by MCFAs with the hydroxyl group at the 2- or 3-position more effectively than nonhydroxylated MCFAs. We also identified a surrogate agonist, 6-n-octylaminouracil (6-OAU), for GPR84. These potential ligands and the surrogate agonist, 6-OAU, stimulated [35S]GTP binding and accumulated phosphoinositides in a GPR84-dependent manner. The surrogate agonist, 6-OAU, internalized GPR84-EGFP from the cell surface. Both the potential ligands and 6-OAU elicited chemotaxis of human polymorphonuclear leukocytes (PMNs) and macrophages and amplified LPS-stimulated production of the proinflammatory cytokine IL-8 from PMNs and TNFα from macrophages. Furthermore, the intravenous injection of 6-OAU raised the blood CXCL1 level in rats, and the inoculation of 6-OAU into the rat air pouch accumulated PMNs and macrophages in the site. Our results indicate a proinflammatory role of GPR84, suggesting that the receptor may be a novel target to treat chronic low grade inflammation associated-disease. PMID:23449982

  4. Retinoic Acid Receptor-Related Orphan Receptors: Critical Roles in Tumorigenesis

    PubMed Central

    Fan, Jinshuo; Lv, Zhilei; Yang, Guanghai; Liao, Ting ting; Xu, Juanjuan; Wu, Feng; Huang, Qi; Guo, Mengfei; Hu, Guorong; Zhou, Mei; Duan, Limin; Liu, Shuqing; Jin, Yang

    2018-01-01

    Retinoic acid receptor-related orphan receptors (RORs) include RORα (NR1F1), RORβ (NR1F2), and RORγ (NR1F3). These receptors are reported to activate transcription through ligand-dependent interactions with co-regulators and are involved in the development of secondary lymphoid tissues, autoimmune diseases, inflammatory diseases, the circadian rhythm, and metabolism homeostasis. Researches on RORs contributing to cancer-related processes have been growing, and they provide evidence that RORs are likely to be considered as potential therapeutic targets in many cancers. RORα has been identified as a potential therapeutic target for breast cancer and has been investigated in melanoma, colorectal colon cancer, and gastric cancer. RORβ is mainly expressed in the central nervous system, but it has also been studied in pharyngeal cancer, uterine leiomyosarcoma, and colorectal cancer, in addition to neuroblastoma, and recent studies suggest that RORγ is involved in various cancers, including lymphoma, melanoma, and lung cancer. Some studies found RORγ to be upregulated in cancer tissues compared with normal tissues, while others indicated the opposite results. With respect to the mechanisms of RORs in cancer, previous studies on the regulatory mechanisms of RORs in cancer were mostly focused on immune cells and cytokines, but lately there have been investigations concentrating on RORs themselves. Thus, this review summarizes reports on the regulation of RORs in cancer and highlights potential therapeutic targets in cancer. PMID:29904382

  5. Mapping General Anesthetic Sites in Heteromeric γ-Aminobutyric Acid Type A Receptors Reveals a Potential For Targeting Receptor Subtypes.

    PubMed

    Forman, Stuart A; Miller, Keith W

    2016-11-01

    IV general anesthetics, including propofol, etomidate, alphaxalone, and barbiturates, produce important actions by enhancing γ-aminobutyric acid type A (GABAA) receptor activation. In this article, we review scientific studies that have located and mapped IV anesthetic sites using photoaffinity labeling and substituted cysteine modification protection. These anesthetics bind in transmembrane pockets between subunits of typical synaptic GABAA receptors, and drugs that display stereoselectivity also show remarkably selective interactions with distinct interfacial sites. These results suggest strategies for developing new drugs that selectively modulate distinct GABAA receptor subtypes.

  6. The nuclear receptor PPARγ individually responds to serotonin- and fatty acid-metabolites

    PubMed Central

    Waku, Tsuyoshi; Shiraki, Takuma; Oyama, Takuji; Maebara, Kanako; Nakamori, Rinna; Morikawa, Kosuke

    2010-01-01

    The nuclear receptor, peroxisome proliferator-activated receptor γ (PPARγ), recognizes various synthetic and endogenous ligands by the ligand-binding domain. Fatty-acid metabolites reportedly activate PPARγ through conformational changes of the Ω loop. Here, we report that serotonin metabolites act as endogenous agonists for PPARγ to regulate macrophage function and adipogenesis by directly binding to helix H12. A cyclooxygenase inhibitor, indomethacin, is a mimetic agonist of these metabolites. Crystallographic analyses revealed that an indole acetate functions as a common moiety for the recognition by the sub-pocket near helix H12. Intriguingly, a serotonin metabolite and a fatty-acid metabolite each bind to distinct sub-pockets, and the PPARγ antagonist, T0070907, blocked the fatty-acid agonism, but not that of the serotonin metabolites. Mutational analyses on receptor-mediated transcription and coactivator binding revealed that each metabolite individually uses coregulator and/or heterodimer interfaces in a ligand-type-specific manner. Furthermore, the inhibition of the serotonin metabolism reduced the expression of the endogenous PPARγ-target gene. Collectively, these results suggest a novel agonism, in which PPARγ functions as a multiple sensor in response to distinct metabolites. PMID:20717101

  7. Influence of sialic acids on the galactose-recognizing receptor of rat peritoneal macrophages.

    PubMed

    Lee, H Y; Kelm, S; Michalski, J C; Schauer, R

    1990-04-01

    The interaction of the galactose-recognizing receptor from rat peritoneal macrophages with ligands containing terminal galactose residues, such as asialoorosomucoid, desialylated erythrocytes or lymphocytes, can be inhibited by free N-acetylneuraminic acid (Neu5Ac) and oligosaccharides or glycoproteins containing this sugar in terminal position. This effect of Neu5Ac on the receptor is specific. The other naturally occurring or most of synthetic neuraminic acid derivatives tested do not exhibit an equivalent inhibitory potency as Neu5Ac. Although free Neu5Ac inhibits 5-fold stronger (K50 = 0.2mM) than free galactose, clustering of Neu5Ac in oligosaccharides and glycoproteins does not lead to stronger inhibition, which is in contrast to galactose-containing ligands. A more branched (triantennary) sialooligosaccharide inhibits less than biantennary and unbranched sialooligosaccharides. This may be the reason, why complex sialic acid-containing ligands like native orosomucoid or blood cells are not bound and internalized by the macrophages. The dissociation of asialoorosomucoid from the receptor is slow under the influence of Neu5Ac and requires relatively high concentrations of this sugar, whereas the dissociation mediated by galactose is rapid and requires lower concentrations. An allosteric influence of Neu5Ac on the binding of galactose by the receptor is discussed.

  8. Developmental toxicity of perfluorononanoic acid is dependent on peroxisome proliferator activated receptor-alpha.

    EPA Science Inventory

    Perfluorononanoic acid (PFNA) is one of the predominant perfluoroalkyl acids in the environment and in tissues of humans and wildlife. PFNA strongly activates the mouse and human peroxisome proliferator-activated receptor-alpha (PPARα) in vitro and negatively impacts development ...

  9. Molecular receptive range variation among mouse odorant receptors for aliphatic carboxylic acids

    PubMed Central

    Repicky, Sarah E.; Luetje, Charles W.

    2009-01-01

    The ability of mammals to identify and distinguish among many thousands of different odorants suggests a combinatorial use of odorant receptors, with each receptor detecting multiple odorants and each odorant interacting with multiple receptors. Numerous receptors may be devoted to the sampling of particularly important regions of odor space. Here we explore the similarities and differences in the molecular receptive ranges of four mouse odorant receptors (MOR23-1, MOR31-4, MOR32-11 and MOR40-4), which have previously been identified as receptors for aliphatic carboxylic acids. Each receptor was expressed in Xenopus oocytes, along with Gαolf and the cystic fibrosis transmembrane regulator to allow electrophysiological assay of receptor responses. We find that even though these receptors are relatively unrelated, there is extensive overlap among their receptive ranges. That is, these receptors sample a similar region of odor space. However, the receptive range of each receptor is unique. Thus, these receptors contribute to the depth of coverage of this small region of odor space. Such a group of receptors with overlapping, but distinct receptive ranges, may participate in making fine distinctions among complex mixtures of closely related odorant compounds. PMID:19166503

  10. L-Amino Acids Elicit Diverse Response Patterns in Taste Sensory Cells: A Role for Multiple Receptors

    PubMed Central

    Pal Choudhuri, Shreoshi; Delay, Rona J.; Delay, Eugene R.

    2015-01-01

    Umami, the fifth basic taste, is elicited by the L-amino acid, glutamate. A unique characteristic of umami taste is the response potentiation by 5’ ribonucleotide monophosphates, which are also capable of eliciting an umami taste. Initial reports using human embryonic kidney (HEK) cells suggested that there is one broadly tuned receptor heterodimer, T1r1+T1r3, which detects L-glutamate and all other L-amino acids. However, there is growing evidence that multiple receptors detect glutamate in the oral cavity. While much is understood about glutamate transduction, the mechanisms for detecting the tastes of other L-amino acids are less well understood. We used calcium imaging of isolated taste sensory cells and taste cell clusters from the circumvallate and foliate papillae of C57BL/6J and T1r3 knockout mice to determine if other receptors might also be involved in detection of L-amino acids. Ratiometric imaging with Fura-2 was used to study calcium responses to monopotassium L-glutamate, L-serine, L-arginine, and L-glutamine, with and without inosine 5’ monophosphate (IMP). The results of these experiments showed that the response patterns elicited by L-amino acids varied significantly across taste sensory cells. L-amino acids other than glutamate also elicited synergistic responses in a subset of taste sensory cells. Along with its role in synergism, IMP alone elicited a response in a large number of taste sensory cells. Our data indicate that synergistic and non-synergistic responses to L-amino acids and IMP are mediated by multiple receptors or possibly a receptor complex. PMID:26110622

  11. Free fatty acid receptors: emerging targets for treatment of diabetes and its complications

    PubMed Central

    Vangaveti, Venkat; Shashidhar, Venkatesh; Jarrod, Ghassan; Baune, Bernhard T.; Kennedy, R. Lee

    2010-01-01

    Fatty acids (FAs) are important as metabolic substrates and as structural components of biological membranes. However, they also function as signalling molecules. Recently, a series of G protein-coupled receptors (GPRs) for FAs has been described and characterized. These receptors have differing specificities for FAs of differing chain length and degree of saturation, for FA derivatives such as oleoylethanolamide, and for oxidized FAs. They are a critical component of the body's nutrient sensing apparatus, and small molecule agonists and antagonists of these receptors show considerable promise in the management of diabetes and its complications. Agonists of the long-chain free fatty acid receptors FFAR1 and GPR119 act as insulin secretagogues, both directly and by increasing incretins. Although, drugs acting at short-chain FFA receptors (FFAR2 and FFAR3) have not yet been developed, they are attractive targets as they regulate nutrient balance through effects in the intestine and adipose tissue. These include regulation of the secretion of cholecystokinin, peptide YY and leptin. Finally, GPR132 is a receptor for oxidized FAs, which may be a sensor of lipid overload and oxidative stress, and which is involved in atherosclerosis. Regulation of its signalling pathways with drugs may decrease the macrovascular risk experienced by diabetic patients. In summary, FA receptors are emerging drug targets that are involved in the regulation of nutrient status and carbohydrate tolerance, and modulators of these receptors may well figure prominently in the next generation of antidiabetic drugs. PMID:23148161

  12. The role of G-protein-coupled receptors in mediating the effect of fatty acids on inflammation and insulin sensitivity.

    PubMed

    Oh, Da Young; Lagakos, William S

    2011-07-01

    Chronic activation of inflammatory pathways mediates the pathogenesis of insulin resistance, and the macrophage/adipocyte nexus provides a key mechanism underlying decreased insulin sensitivity. Free fatty acids are important in the pathogenesis of insulin resistance, although their precise mechanisms of action have yet to be fully elucidated. Recently, a family of G-protein-coupled receptors has been identified that exhibits high affinity for fatty acids. This review summarizes recent findings on six of these receptors, their ligands, and their potential physiological functions in vivo. Upon activation, the free fatty acid receptors affect inflammation, glucose metabolism, and insulin sensitivity. Genetic deletion of GPR40 and GPR41, receptors for long-chain and short-chain fatty acids, respectively, results in resistance to diet-induced obesity. Deletion of GPR43 and GPR84 exacerbates inflammation, and deletion of the long-chain fatty acid receptors GPR119 and GPR120 reduces or is predicted to reduce glucose tolerance. These studies provide a new understanding of the general biology of gastric motility and also shed valuable insight into some potentially beneficial therapeutic targets. Furthermore, highly selective agonists or antagonists for the free fatty acid receptors have been developed and look promising for treating various metabolic diseases.

  13. Free fatty acid receptors act as nutrient sensors to regulate energy homeostasis.

    PubMed

    Ichimura, Atsuhiko; Hirasawa, Akira; Hara, Takafumi; Tsujimoto, Gozoh

    2009-09-01

    Free fatty acids (FFAs) have been demonstrated to act as ligands of several G-protein-coupled receptors (GPCRs) (FFAR1, FFAR2, FFAR3, GPR84, and GPR120). These fatty acid receptors are proposed to play critical roles in a variety of types of physiological homeostasis. FFAR1 and GPR120 are activated by medium- and long-chain FFAs. GPR84 is activated by medium-chain, but not long-chain, FFAs. In contrast, FFAR2 and FFAR3 are activated by short-chain FFAs. FFAR1 is expressed mainly in pancreatic beta-cells and mediates insulin secretion, whereas GPR120 is expressed abundantly in the intestine and promotes the secretion of glucagon-like peptide-1 (GLP-1). FFAR3 is expressed in enteroendocrine cells and regulates host energy balance through effects that are dependent upon the gut microbiota. In this review, we summarize the identification, structure, and pharmacology of these receptors and present an essential overview of the current understanding of their physiological roles.

  14. Analysis of ileal sodium/bile acid cotransporter and related nuclear receptor genes in a family with multiple cases of idiopathic bile acid malabsorption

    PubMed Central

    Montagnani, Marco; Abrahamsson, Anna; Gälman, Cecilia; Eggertsen, Gösta; Marschall, Hanns-Ulrich; Ravaioli, Elisa; Einarsson, Curt; Dawson, Paul A

    2006-01-01

    The etiology of most cases of idiopathic bile acid malabsorption (IBAM) is unknown. In this study, a Swedish family with bile acid malabsorption in three consecutive generations was screened for mutations in the ileal apical sodium-bile acid cotransporter gene (ASBT; gene symbol, SLC10A2) and in the genes for several of the nuclear receptors known to be important for ASBT expression: the farnesoid X receptor (FXR) and peroxisome proliferator activated receptor alpha (PPARα). The patients presented with a clinical history of idiopathic chronic watery diarrhea, which was responsive to cholestyramine treatment and consistent with IBAM. Bile acid absorption was determined using 75Se-homocholic acid taurine (SeHCAT); bile acid synthesis was estimated by measuring the plasma levels of 7α-hydroxy-4-cholesten-3-one (C4). The ASBT, FXR, and PPARα genes in the affected and unaffected family members were analyzed using single stranded conformation polymorphism (SSCP), denaturing HPLC, and direct sequencing. No ASBT mutations were identified and the ASBT gene did not segregate with the bile acid malabsorption phenotype. Similarly, no mutations or polymorphisms were identified in the FXR or PPARα genes associated with the bile acid malabsorption phenotype. These studies indicate that the intestinal bile acid malabsorption in these patients cannot be attributed to defects in ASBT. In the absence of apparent ileal disease, alternative explanations such as accelerated transit through the small intestine may be responsible for the IBAM. PMID:17171805

  15. Enhancement of gamma-aminobutyric acid receptor binding by protopine-type alkaloids.

    PubMed

    Kardos, J; Blaskó, G; Simonyi, M

    1986-06-01

    Protopine, cryptopine and allocryptopine were demonstrated to enhance 3H-gamma-aminobutyric acid (3H-GABA) binding to rat brain synaptic membrane receptors. The above finding might be indicative of benzodiazepine-like activity of these alkaloids.

  16. Prefrontal gamma-aminobutyric acid type A receptor insertion controls cue-induced relapse to nicotine seeking.

    PubMed

    Lubbers, Bart R; van Mourik, Yvar; Schetters, Dustin; Smit, August B; De Vries, Taco J; Spijker, Sabine

    2014-11-01

    Current smoking cessation therapies offer limited success, as relapse rates remain high. Nicotine, which is the major component of tobacco smoke, is thought to be primarily responsible for the addictive properties of tobacco. However, little is known about the molecular mechanisms underlying nicotine relapse, hampering development of more effective therapies. The objective of this study was to elucidate the role of medial prefrontal cortex (mPFC) glutamatergic and gamma-aminobutyric acid (GABA)ergic receptors in controlling relapse to nicotine seeking. Using an intravenous self-administration model, we studied glutamate and gamma-aminobutyric acid receptor regulation in the synaptic membrane fraction of the rat mPFC following extinction and cue-induced relapse to nicotine seeking. Subsequently, we locally intervened at the level of GABAergic signaling by using a mimetic peptide of the GABA receptor associated protein-interacting domain of GABA type A (GABAA) receptor subunit γ2 (TAT-GABAγ2) and muscimol, a GABAA receptor agonist. Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid and N-methyl-D-aspartate receptors were not regulated after the 30-min relapse test. However, GABAA receptor subunits α1 and γ2 were upregulated, and interference with GABAA receptor insertion in the cell membrane using the TAT-GABAγ2 peptide in the dorsal mPFC, but not the ventral mPFC, significantly increased responding during relapse. Increasing GABAA transmission with muscimol in the dorsal and ventral mPFC attenuated relapse. These data indicate that cue-induced relapse entails a GABAergic plasticity mechanism that limits nicotine seeking by restoring inhibitory control in the dorsal mPFC. GABAA receptor-mediated neurotransmission in the dorsal mPFC constitutes a possible future therapeutic target for maintaining smoking abstinence. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  17. Bacterial D-Amino Acids Suppress Sinonasal Innate Immunity Through Sweet Taste Receptors in Solitary Chemosensory Cells

    PubMed Central

    Lee, Robert J.; Hariri, Benjamin M.; McMahon, Derek B.; Chen, Bei; Doghramjii, Laurel; Adappa, Nithin D.; Palmer, James N.; Kennedy, David W.; Jiang, Peihua; Margolskee, Robert F.; Cohen, Noam A.

    2017-01-01

    In the upper respiratory epithelium, bitter and sweet taste receptors present in solitary chemosensory cells influence antimicrobial innate immune defense responses. Whereas activation of the bitter taste receptor (T2R) stimulates surrounding epithelial cells to release antimicrobial peptides, activation of the sweet taste receptor (T1R) in the same cells inhibits this response. It is thought that this mechanism exists to control the magnitude of antimicrobial peptide release based upon the sugar content of airway surface liquid. We hypothesized that D-amino acids, which are produced by various bacteria and activate T1R in taste receptor cells in the mouth, may also activate T1R in the airway. Here, we show that both the T1R2 and T1R3 subunits of the sweet taste receptor (T1R2/3) are present in the same chemosensory cells of primary human sinonasal epithelial cultures. Respiratory isolates of Staphylococcus species, but not Pseudomonas aeruginosa, produced at least two D-amino acids that activate the sweet taste receptor. In addition to inhibiting P. aeruginosa biofilm formation, D-amino acids derived from Staphylococcus inhibited T2R-mediated signaling and defensin secretion in sinonasal cells by activating T1R2/3. D-amino acid–mediated activation of T1R2/3 also enhanced epithelial cell death during challenge with Staphylococcus aureus in the presence of the bitter-receptor–activating compound denatonium benzoate. These data establish a potential mechanism for interkingdom signaling in the airway mediated by bacterial D-amino acids and the mammalian sweet taste receptor in airway chemosensory cells. PMID:28874606

  18. mRNA levels of enzymes and receptors implicated in arachidonic acid metabolism in gliomas.

    PubMed

    De Armas, Rafael; Durand, Karine; Guillaudeau, Angélique; Weinbreck, Nicolas; Robert, Sandrine; Moreau, Jean-Jacques; Caire, François; Acosta, Gisela; Pebet, Matias; Chaunavel, Alain; Marin, Benoît; Labrousse, François; Denizot, Yves

    2010-07-01

    Gliomas are tumors of the central nervous system derived from glial cells. They show cellular heterogeneity and lack specific diagnostic markers. Although a possible role for the eicosanoid cascade has been suggested in glioma tumorigenesis, the relationship between enzymes and receptors implicated in arachidonic acid metabolism, with histological tumor type has not yet been determined. Quantitative real-time reverse transcription-polymerase chain reaction was performed to measure and compare transcript levels of enzymes and receptors implicated in both lipoxygenase and cyclooxygenase pathways between oligodendrogliomas, astrocytomas, glioblastomas and mixed oligoastrocytomas. Arachidonic acid metabolism-related enzymes and receptor transcripts (i) were underexpressed in classical oligodendrogliomas compared to astrocytomas and/or glioblastomas, (ii) differed between astrocytomas and glioblastomas and (iii) had an intermediate expression in mixed oligoastrocytomas. mRNA levels of enzymes and receptors implicated both in lipoxygenase and cyclooxygenase pathways differed significantly in gliomas according to the histological type. Copyright 2010 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  19. Metabolism meets immunity: The role of free fatty acid receptors in the immune system.

    PubMed

    Alvarez-Curto, Elisa; Milligan, Graeme

    2016-08-15

    There are significant numbers of nutrient sensing G protein-coupled receptors (GPCRs) that can be found in cells of the immune system and in tissues that are involved in metabolic function, such as the pancreas or the intestinal epithelium. The family of free fatty acid receptors (FFAR1-4, GPR84), plus a few other metabolite sensing receptors (GPR109A, GPR91, GPR35) have been for this reason the focus of studies linking the effects of nutrients with immunological responses. A number of the beneficial anti-inflammatory effects credited to dietary fats such as omega-3 fatty acids are attributed to their actions on FFAR4.This might play an important protective role in the development of obesity, insulin resistance or asthma. The role of the short-chain fatty acids resulting from fermentation of fibre by the intestinal microbiota in regulating acute inflammatory responses is also discussed. Finally we assess the therapeutic potential of this family of receptors to treat pathologies where inflammation is a major factor such as type 2 diabetes, whether by the use of novel synthetic molecules or by the modulation of the individual's diet. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  20. Human sweet taste receptor mediates acid-induced sweetness of miraculin

    PubMed Central

    Koizumi, Ayako; Tsuchiya, Asami; Nakajima, Ken-ichiro; Ito, Keisuke; Terada, Tohru; Shimizu-Ibuka, Akiko; Briand, Loïc; Asakura, Tomiko; Misaka, Takumi; Abe, Keiko

    2011-01-01

    Miraculin (MCL) is a homodimeric protein isolated from the red berries of Richadella dulcifica. MCL, although flat in taste at neutral pH, has taste-modifying activity to convert sour stimuli to sweetness. Once MCL is held on the tongue, strong sweetness is sensed over 1 h each time we taste a sour solution. Nevertheless, no molecular mechanism underlying the taste-modifying activity has been clarified. In this study, we succeeded in quantitatively evaluating the acid-induced sweetness of MCL using a cell-based assay system and found that MCL activated hT1R2-hT1R3 pH-dependently as the pH decreased from 6.5 to 4.8, and that the receptor activation occurred every time an acid solution was applied. Although MCL per se is sensory-inactive at pH 6.7 or higher, it suppressed the response of hT1R2-hT1R3 to other sweeteners at neutral pH and enhanced the response at weakly acidic pH. Using human/mouse chimeric receptors and molecular modeling, we revealed that the amino-terminal domain of hT1R2 is required for the response to MCL. Our data suggest that MCL binds hT1R2-hT1R3 as an antagonist at neutral pH and functionally changes into an agonist at acidic pH, and we conclude this may cause its taste-modifying activity. PMID:21949380

  1. Antiageing Mechanisms of a Standardized Supercritical CO2 Preparation of Black Jack (Bidens pilosa L.) in Human Fibroblasts and Skin Fragments

    PubMed Central

    Dieamant, Gustavo; Pereda, Maria Del Carmen V.; Nogueira, Cecília; Eberlin, Samara; Facchini, Gustavo; Checon, Juliana Tibério; Cesar, Camila Kappke; Mussi, Lilian; Polezel, Márcio Antonio; Martins-Oliveira, Divino; Di Stasi, Luiz Claudio

    2015-01-01

    The use of topical retinoids to treat skin disorders and ageing can induce local reactions, while oral retinoids are potent teratogens and produce several unwanted effects. This way, efforts to explore complementary care resources should be supported. Based on this, we evaluate the antiageing effects of a supercritical CO2 extract from Bidens pilosa L. (BPE-CO2A) containing a standardized multicomponent mixture of phytol, linolenic, palmitic, linoleic, and oleic acids. BPE-CO2A was assessed for its effects on human dermal fibroblasts (TGF-β1 and FGF levels using ELISA; collagen, elastin, and glycosaminoglycan by colorimetric assays, and mRNA expression of RXR, RAR, and EGFr by qRT-PCR) and human skin fragments (RAR, RXR, collagen, elastin, and glycosaminoglycan by immunohistochemical analysis). Levels of extracellular matrix elements, TGF-β1 and FGF, and EGFr gene expression were significantly increased by BPE-CO2A. The modulation of RXR and RAR was positively demonstrated after the treatment with BPE-CO2A or phytol, a component of BPE-CO2A. The effects produced by BPE-CO2A were similar to or better than those produced by retinol and retinoic acid. The ability to stimulate extracellular matrix elements, increase growth factors, and modulate retinoid and rexinoid receptors provides a basis for the development of preparation containing BPE-CO2A as an antiageing/skin-repair agent. PMID:25883669

  2. Computational Analysis of the Interaction Energies between Amino Acid Residues of the Measles Virus Hemagglutinin and Its Receptors.

    PubMed

    Xu, Fengqi; Tanaka, Shigenori; Watanabe, Hirofumi; Shimane, Yasuhiro; Iwasawa, Misako; Ohishi, Kazue; Maruyama, Tadashi

    2018-05-03

    Measles virus (MV) causes an acute and highly devastating contagious disease in humans. Employing the crystal structures of three human receptors, signaling lymphocyte-activation molecule (SLAM), CD46, and Nectin-4, in complex with the measles virus hemagglutinin (MVH), we elucidated computationally the details of binding energies between the amino acid residues of MVH and those of the receptors with an ab initio fragment molecular orbital (FMO) method. The calculated inter-fragment interaction energies (IFIEs) revealed a number of significantly interacting amino acid residues of MVH that played essential roles in binding to the receptors. As predicted from previously reported experiments, some important amino-acid residues of MVH were shown to be common but others were specific to interactions with the three receptors. Particularly, some of the (non-polar) hydrophobic residues of MVH were found to be attractively interacting with multiple receptors, thus indicating the importance of the hydrophobic pocket for intermolecular interactions (especially in the case of Nectin-4). In contrast, the electrostatic interactions tended to be used for specific molecular recognition. Furthermore, we carried out FMO calculations for in silico experiments of amino acid mutations, finding reasonable agreements with virological experiments concerning the substitution effect of residues. Thus, the present study demonstrates that the electron-correlated FMO method is a powerful tool to search exhaustively for amino acid residues that contribute to interactions with receptor molecules. It is also applicable for designing inhibitors of MVH and engineered MVs for cancer therapy.

  3. [Studies on the structure-activity relationship of retinoids--Hansch analysis and 3D-OSAR studies on specific ligands of retinoid x receptor].

    PubMed

    Huang, N; Chu, F; Guo, Z

    1998-06-01

    Retinoids (Vitamin A, its metabolites and synthetic analogues) play important roles in a variety of biological processes, including cellular differentiation, proliferation and apoptosis. The many diverse actions of retinoids attribute to the ability of regulating transcription of different target genes through activation of multiple retinoid nuclear receptors (RAR of RXR). So, retinoids with selective binding ability to specific receptor may not only have improved therapeutic indices, but may also be invaluable for elucidating the molecular mechanism of retinoidal transcriptional activation. Based on the two dimensional and three dimensional quantitative structure-activity relationships of specific ligands of RXR, we carried out mimesis of environment of ligands interacting with their receptor and, to some extent, mapping the topological and physico-chemical characteristics of receptor. The knowledge of the QSAR study will offer detailed molecular information for design, synthesis and biological evaluation in drug research and development.

  4. Effects of Alpha-Lipoic Acid on Oxidative Stress and Kinin Receptor Expression in Obese Zucker Diabetic Fatty Rats.

    PubMed

    Midaoui, Adil El; Talbot, Sébastien; Lahjouji, Karim; Dias, Jenny Pena; Fantus, I George; Couture, Réjean

    2015-06-01

    To investigate the impact of alpha-lipoic acid on superoxide anion production and NADPH oxidase activity as well as on the expression of kinin B1 and B2 receptors in key organs of obese Zucker Diabetic Fatty rats. Superoxide anion production was measured by lucigenin chemiluminescence. Kinin B1 and B2 receptors expression was measured at protein and mRNA levels by western blot and qRT-PCR in key organs of Zucker Diabetic Fatty and Zucker lean control rats treated for a period of 6 weeks with a standard diet or a diet containing the antioxidant α-lipoic acid (1 g/kg). Superoxide anion production and NADPH oxidase activity were significantly enhanced in aorta and adipose tissue of Zucker Diabetic Fatty rats. Kinin B1 and B2 receptors expression levels were also significantly increased in the liver and the gastrocnemius muscle of Zucker Diabetic Fatty rats. Expression of both receptors was not altered in the pancreas of Zucker Diabetic Fatty rats and was undetectable in white retroperitoneal adipose tissue. Alpha-lipoic acid prevented the rise in NADPH oxidase activity in aorta and epididymal adipose tissue of Zucker Diabetic Fatty rats and the upregulation of kinin B1 receptor in liver and gastrocnemius muscle and that of kinin B2 receptor in the liver. Alpha-lipoic acid treatment was found to prevent the final body weight increase without affecting significantly hyperglycemia, hyperinsulinemia and insulin resistance index in Zucker Diabetic Fatty rats. Findings support the hypothesis that oxidative stress is implicated in the induction of kinin B1 receptor in Zucker Diabetic Fatty rats. The ability of α-lipoic acid to blunt the body weight gain appears to be mediated in part by preventing NADPH oxidase activity rise in adipose tissue and reversing the hepatic upregulation of kinin B1 receptor in Zucker Diabetic Fatty rats.

  5. Dietary fatty acids regulate hepatic low density lipoprotein (LDL) transport by altering LDL receptor protein and mRNA levels.

    PubMed Central

    Horton, J D; Cuthbert, J A; Spady, D K

    1993-01-01

    The concentration of LDL in plasma is strongly influenced by the amount and the type of lipid in the diet. Recent studies in the hamster have shown that dietary fatty acids differentially affect circulating LDL levels primarily by altering receptor-dependent LDL uptake in the liver. To investigate the mechanistic basis of this effect, rates of receptor-dependent LDL transport in the liver were correlated with LDL receptor protein and mRNA levels in hamsters fed safflower oil or coconut oil and varying amounts of cholesterol. Hepatic LDL receptor activity was significantly lower in animals fed coconut oil than in animals fed safflower oil at all levels of cholesterol intake (26, 53, and 61% lower at cholesterol intakes of 0, 0.06, and 0.12%, respectively). These fatty acid-induced changes in hepatic LDL receptor activity were accompanied by parallel changes in hepatic LDL receptor protein and mRNA levels, suggesting that dietary fatty acids regulate the LDL receptor pathway largely at the mRNA level. Images PMID:8349814

  6. Receptor for protons: First observations on Acid Sensing Ion Channels.

    PubMed

    Krishtal, Oleg

    2015-07-01

    The history of ASICs began in 1980 with unexpected observation. The concept of highly selective Na(+) current gated by specific receptors for protons was not easily accepted. It took 16 years to get these receptor/channels cloned and start a new stage in their investigation. "The receptor for protons" became ASIC comprising under this name a family of receptor/channels ubiquitous for mammalian nervous system, both peripheral and central. The role of ASICs as putative nociceptors was suggested almost immediately after their discovery. This role subsequently was proven in many forms of pain-related phenomena. Many other functions of ASICs have been also found or primed for speculations both in physiology and in disease. Despite the width of field and strength of efforts, numerous basic questions are to be answered before we understand how the local changes in pH in the nervous tissue transform into electric and messenger signaling via ASICs as transducers. This article is part of the Special Issue entitled 'Acid-Sensing Ion Channels in the Nervous System'. Copyright © 2015. Published by Elsevier Ltd.

  7. Cross-calibration of Fuji TR image plate and RAR 2492 x-ray film to determine the response of a DITABIS Super Micron image plate scanner

    NASA Astrophysics Data System (ADS)

    Dunham, G.; Harding, E. C.; Loisel, G. P.; Lake, P. W.; Nielsen-Weber, L. B.

    2016-11-01

    Fuji TR image plate is frequently used as a replacement detector medium for x-ray imaging and spectroscopy diagnostics at NIF, Omega, and Z facilities. However, the familiar Fuji BAS line of image plate scanners is no longer supported by the industry, and so a replacement scanning system is needed. While the General Electric Typhoon line of scanners could replace the Fuji systems, the shift away from photo stimulated luminescence units to 16-bit grayscale Tag Image File Format (TIFF) leaves a discontinuity when comparing data collected from both systems. For the purposes of quantitative spectroscopy, a known unit of intensity applied to the grayscale values of the TIFF is needed. The DITABIS Super Micron image plate scanning system was tested and shown to potentially rival the resolution and dynamic range of Kodak RAR 2492 x-ray film. However, the absolute sensitivity of the scanner is unknown. In this work, a methodology to cross calibrate Fuji TR image plate and the absolutely calibrated Kodak RAR 2492 x-ray film is presented. Details of the experimental configurations used are included. An energy dependent scale factor to convert Fuji TR IP scanned on a DITABIS Super Micron scanner from 16-bit grayscale TIFF to intensity units (i.e., photons per square micron) is discussed.

  8. The Gamma-Aminobutyric Acid B Receptor in Depression and Reward.

    PubMed

    Jacobson, Laura H; Vlachou, Styliani; Slattery, David A; Li, Xia; Cryan, John F

    2018-06-01

    The metabotropic gamma-aminobutyric acid B (GABA B ) receptor was the first described obligate G protein-coupled receptor heterodimer and continues to set the stage for discoveries in G protein-coupled receptor signaling complexity. In this review, dedicated to the life and work of Athina Markou, we explore the role of GABA B receptors in depression, reward, and the convergence of these domains in anhedonia, a shared symptom of major depressive disorder and withdrawal from drugs of abuse. GABA B receptor expression and function are enhanced by antidepressants and reduced in animal models of depression. Generally, GABA B receptor antagonists are antidepressant-like and agonists are pro-depressive. Exceptions to this rule likely reflect the differential influence of GABA B1 isoforms in depression-related behavior and neurobiology, including the anhedonic effects of social stress. A wealth of data implicate GABA B receptors in the rewarding effects of drugs of abuse. We focus on nicotine as an example. GABA B receptor activation attenuates, and deactivation enhances, nicotine reward and associated neurobiological changes. In nicotine withdrawal, however, GABA B receptor agonists, antagonists, and positive allosteric modulators enhance anhedonia, perhaps owing to differential effects of GABA B1 isoforms on the dopaminergic system. Nicotine cue-induced reinstatement is more reliably attenuated by GABA B receptor activation. Separation of desirable and undesirable side effects of agonists is achievable with positive allosteric modulators, which are poised to enter clinical studies for drug abuse. GABA B1 isoforms are key to understanding the neurobiology of anhedonia, whereas allosteric modulators may offer a mechanism for targeting specific brain regions and processes associated with reward and depression. Copyright © 2018 Society of Biological Psychiatry. All rights reserved.

  9. Nicotinic Acid Adenine Dinucleotide Phosphate Analogs Substituted on the Nicotinic Acid and Adenine Ribosides. Effects on Receptor-Mediated Ca2+ release

    PubMed Central

    Trabbic, Christopher J.; Zhang, Fan; Walseth, Timothy F.; Slama, James T.

    2015-01-01

    Nicotinic acid adenine dinucleotide phosphate (NAADP) is a Ca2+ releasing intracellular second messenger in both mammals and echinoderms. We report that large functionalized substituents introduced at the nicotinic acid 5-position are recognized by the sea urchin receptor, albeit with a 20–500 fold loss in agonist potency. 5-(3-Azidopropyl)-NAADP was shown to release Ca2+ with an EC50 of 31 µM and to compete with NAADP for receptor binding with an IC50 of 56 nM. Attachment of charged groups to the nicotinic acid of NAADP is associated with loss of activity, suggesting that the nicotinate riboside moiety is recognized as a neutral zwitterion. Substituents (Br- and N3-) can be introduced at the 8-adenosyl position of NAADP while preserving high potency and agonist efficacy and an NAADP derivative substituted at both the 5-position of the nicotinic acid and at the 8-adenosyl position was also recognized although the agonist potency was significantly reduced. PMID:25826221

  10. HAL-RAR (Doppler guided haemorrhoid artery ligation with recto-anal repair) is a safe and effective procedure for haemorrhoids. Results of a prospective study after two-years follow-up.

    PubMed

    Hoyuela, Carlos; Carvajal, Fernando; Juvany, Montserrat; Troyano, Daniel; Trias, Miquel; Martrat, Antoni; Ardid, Jordi; Obiols, Joan

    2016-04-01

    To analyse prospectively results of HAL-RAR technique by evaluating pain, perioperative complications and clinical outcome after two years followup. A prospective study design including 30 consecutive patients with haemorrhoids grade III-IV treated from June 2012. After discharge, patients received a specific questionnaire to record postoperative pain, delayed complications, evolution/disappearance of the symptoms that led to the surgical intervention (bleeding, prolapse, itching, pain and soiling). A visual analog scale (VAS) was used to measure pain. Outpatient follow-up was carried out at 7 days, and 1, 6 and 12 months and annually thereafter. Pre, intra and postoperative data (including physical examination) had been recorded prospectively. The median operating time (range) was 40 (26-60) minutes. Average hospital stay (range) was 11 (3-25) hours. No postoperative complications were observed in 29 cases (96.6%). Median follow-up was 26 (12-36) months. All the patients attended the follow-up. Mean postoperative pain was VAS = 1.7 on the seventh day and it was practically non-existent (VAS = 0.7) 1 month after the procedure. 87.5% of patients confirmed complete relief of symptoms after 30 days and 93% of patients feel free of symptoms 6 months after the procedure. No patient has experienced late complications as dyschezia, urgency, soiling or faecal incontinence. After 24 months follow-up, recurrence of bleeding and prolapse was observed in only 1 patient; 93% of patients have considered results of HAL-RAR as very good or excellent. HAL-RAR is safe and almost painless technique and it has very good results in the control of haemorrhoidal symptoms. This procedure should be considered as an effective first treatment option for haemorrhoids. Copyright © 2016 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

  11. Phosphorylation and Internalization of Lysophosphatidic Acid Receptors LPA1, LPA2, and LPA3

    PubMed Central

    Alcántara-Hernández, Rocío; Hernández-Méndez, Aurelio; Campos-Martínez, Gisselle A.; Meizoso-Huesca, Aldo; García-Sáinz, J. Adolfo

    2015-01-01

    Results The lysophosphatidic acid receptors LPA1, LPA2, and LPA3 were individually expressed in C9 cells and their signaling and regulation were studied. Agonist-activation increases intracellular calcium concentration in a concentration-dependent fashion. Phorbol myristate acetate markedly inhibited LPA1- and LPA3-mediated effect, whereas that mediated by LPA2 was only partially diminished; the actions of the phorbol ester were inhibited by bisindolylmaleimide I and by overnight incubation with the protein kinase C activator, which leads to down regulation of this protein kinase. Homologous desensitization was also observed for the three LPA receptors studied, with that of LPA2 receptors being consistently of lesser magnitude; neither inhibition nor down-regulation of protein kinase C exerted any effect on homologous desensitization. Activation of LPA1–3 receptors induced ERK 1/2 phosphorylation; this effect was markedly attenuated by inhibition of epidermal growth factor receptor tyrosine kinase activity, suggesting growth factor receptor transactivation in this effect. Lysophosphatidic acid and phorbol myristate acetate were able to induce LPA1–3 phosphorylation, in time- and concentration-dependent fashions. It was also clearly observed that agonists and protein kinase C activation induced internalization of these receptors. Phosphorylation of the LPA2 subtype required larger concentrations of these agents and its internalization was less intense than that of the other subtypes. Conclusion Our data show that these three LPA receptors are phosphoproteins whose phosphorylation state is modulated by agonist-stimulation and protein kinase C-activation and that differences in regulation and cellular localization exist, among the subtypes. PMID:26473723

  12. A New Pain Regulatory System via the Brain Long Chain Fatty Acid Receptor GPR40/FFA1 Signal.

    PubMed

    Nakamoto, Kazuo

    2017-01-01

    An increasingly large number of pharmacological and physiological works on fatty acids have shown that the functional properties of fatty acids are regulated by the amount of individual fatty acid intake and the distribution of fatty acids among organs. Recently, it has been determined that G-protein-coupled receptor 40/free fatty acid receptor 1 (GPR40/FFA1) is activated by long-chain fatty acids, such as docosahexaenoic acid (DHA). GPR40/FFA1 is mainly expressed in the β cell of the pancreas, spinal cord and brain. It is reported that this receptor has a functional role in controlling blood glucose levels via the modulation of insulin secretion. However, its physiological function in the brain remains unknown. Our previous studies have shown that GPR40/FFA1 is expressed in pro-opiomelanocortin (POMC)-positive neurons of the arcuate nucleus, serotonergic neurons in the nucleus raphe magnus, and in noradrenergic neurons in the locus coeruleus. Furthermore, the intracerebroventricular injection of DHA or GW9508, which is a selective GPR40/FFA1 agonist, attenuates formalin-induced inflammatory pain behavior through increasing β-endorphin release in the hypothalamus. It also suppresses complete Freund's adjuvant-induced mechanical allodynia and thermal hyperalgesia. Our findings suggest that brain free long-chain fatty acids-GPR40/FFA1 signaling might have an important role in the modulation of endogenous pain control systems. In this review, I discuss the current status and our recent study regarding a new pain regulatory system via the brain long chain fatty acid receptor GPR40/FFA1 signal.

  13. Modification on ursodeoxycholic acid (UDCA) scaffold. discovery of bile acid derivatives as selective agonists of cell-surface G-protein coupled bile acid receptor 1 (GP-BAR1).

    PubMed

    Sepe, Valentina; Renga, Barbara; Festa, Carmen; D'Amore, Claudio; Masullo, Dario; Cipriani, Sabrina; Di Leva, Francesco Saverio; Monti, Maria Chiara; Novellino, Ettore; Limongelli, Vittorio; Zampella, Angela; Fiorucci, Stefano

    2014-09-25

    Bile acids are signaling molecules interacting with the nuclear receptor FXR and the G-protein coupled receptor 1 (GP-BAR1/TGR5). GP-BAR1 is a promising pharmacological target for the treatment of steatohepatitis, type 2 diabetes, and obesity. Endogenous bile acids and currently available semisynthetic bile acids are poorly selective toward GP-BAR1 and FXR. Thus, in the present study we have investigated around the structure of UDCA, a clinically used bile acid devoid of FXR agonist activity, to develop a large family of side chain modified 3α,7β-dihydroxyl cholanoids that selectively activate GP-BAR1. In vivo and in vitro pharmacological evaluation demonstrated that administration of compound 16 selectively increases the expression of pro-glucagon 1, a GP-BAR1 target, in the small intestine, while it had no effect on FXR target genes in the liver. Further, compound 16 results in a significant reshaping of bile acid pool in a rodent model of cholestasis. These data demonstrate that UDCA is a useful scaffold to generate novel and selective steroidal ligands for GP-BAR1.

  14. Allspice and Clove As Source of Triterpene Acids Activating the G Protein-Coupled Bile Acid Receptor TGR5

    PubMed Central

    Ladurner, Angela; Zehl, Martin; Grienke, Ulrike; Hofstadler, Christoph; Faur, Nadina; Pereira, Fátima C.; Berry, David; Dirsch, Verena M.; Rollinger, Judith M.

    2017-01-01

    Worldwide, metabolic diseases such as obesity and type 2 diabetes have reached epidemic proportions. A major regulator of metabolic processes that gained interest in recent years is the bile acid receptor TGR5 (Takeda G protein-coupled receptor 5). This G protein-coupled membrane receptor can be found predominantly in the intestine, where it is mainly responsible for the secretion of the incretins glucagon-like peptide 1 (GLP-1) and peptide YY (PYY). The aim of this study was (i) to identify plant extracts with TGR5-activating potential, (ii) to narrow down their activity to the responsible constituents, and (iii) to assess whether the intestinal microbiota produces transformed metabolites with a different activity profile. Chenodeoxycholic acid (CDCA) served as positive control for both, the applied cell-based luciferase reporter gene assay for TGR5 activity and the biotransformation assay using mouse fecal slurry. The suitability of the workflow was demonstrated by the biotransformation of CDCA to lithocholic acid resulting in a distinct increase in TGR5 activity. Based on a traditional Tibetan formula, 19 plant extracts were selected and investigated for TGR5 activation. Extracts from the commonly used spices Syzygium aromaticum (SaroE, clove), Pimenta dioica (PdioE, allspice), and Kaempferia galanga (KgalE, aromatic ginger) significantly increased TGR5 activity. After biotransformation, only KgalE showed significant differences in its metabolite profile, which, however, did not alter its TGR5 activity compared to non-transformed KgalE. UHPLC-HRMS (high-resolution mass spectrometry) analysis revealed triterpene acids (TTAs) as the main constituents of the extracts SaroE and PdioE. Identification and quantification of TTAs in these two extracts as well as comparison of their TGR5 activity with reconstituted TTA mixtures allowed the attribution of the TGR5 activity to TTAs. EC50s were determined for the main TTAs, i.e., oleanolic acid (2.2 ± 1.6 μM), ursolic

  15. Role of Vitamin A/Retinoic Acid in Regulation of Embryonic and Adult Hematopoiesis.

    PubMed

    Cañete, Ana; Cano, Elena; Muñoz-Chápuli, Ramón; Carmona, Rita

    2017-02-20

    Vitamin A is an essential micronutrient throughout life. Its physiologically active metabolite retinoic acid (RA), acting through nuclear retinoic acid receptors (RARs), is a potent regulator of patterning during embryonic development, as well as being necessary for adult tissue homeostasis. Vitamin A deficiency during pregnancy increases risk of maternal night blindness and anemia and may be a cause of congenital malformations. Childhood Vitamin A deficiency can cause xerophthalmia, lower resistance to infection and increased risk of mortality. RA signaling appears to be essential for expression of genes involved in developmental hematopoiesis, regulating the endothelial/blood cells balance in the yolk sac, promoting the hemogenic program in the aorta-gonad-mesonephros area and stimulating eryrthropoiesis in fetal liver by activating the expression of erythropoietin. In adults, RA signaling regulates differentiation of granulocytes and enhances erythropoiesis. Vitamin A may facilitate iron absorption and metabolism to prevent anemia and plays a key role in mucosal immune responses, modulating the function of regulatory T cells. Furthermore, defective RA/RARα signaling is involved in the pathogenesis of acute promyelocytic leukemia due to a failure in differentiation of promyelocytes. This review focuses on the different roles played by vitamin A/RA signaling in physiological and pathological mouse hematopoiesis duddurring both, embryonic and adult life, and the consequences of vitamin A deficiency for the blood system.

  16. Pharmacologically relevant receptor binding characteristics and 5alpha-reductase inhibitory activity of free Fatty acids contained in saw palmetto extract.

    PubMed

    Abe, Masayuki; Ito, Yoshihiko; Oyunzul, Luvsandorj; Oki-Fujino, Tomomi; Yamada, Shizuo

    2009-04-01

    Saw palmetto extract (SPE), used widely for the treatment of benign prostatic hyperplasia (BPH) has been shown to bind alpha(1)-adrenergic, muscarinic and 1,4-dihydropyridine (1,4-DHP) calcium channel antagonist receptors. Major constituents of SPE are lauric acid, oleic acid, myristic acid, palmitic acid and linoleic acid. The aim of this study was to investigate binding affinities of these fatty acids for pharmacologically relevant (alpha(1)-adrenergic, muscarinic and 1,4-DHP) receptors. The fatty acids inhibited specific [(3)H]prazosin binding in rat brain in a concentration-dependent manner with IC(50) values of 23.8 to 136 microg/ml, and specific (+)-[(3)H]PN 200-110 binding with IC(50) values of 24.5 to 79.5 microg/ml. Also, lauric acid, oleic acid, myristic acid and linoleic acid inhibited specific [(3)H]N-methylscopolamine ([(3)H]NMS) binding in rat brain with IC(50) values of 56.4 to 169 microg/ml. Palmitic acid had no effect on specific [(3)H]NMS binding. The affinity of oleic acid, myristic acid and linoleic acid for each receptor was greater than the affinity of SPE. Scatchard analysis revealed that oleic acid and lauric acid caused a significant decrease in the maximal number of binding sites (B(max)) for [(3)H]prazosin, [(3)H]NMS and (+)-[(3)H]PN 200-110. The results suggest that lauric acid and oleic acid bind noncompetitively to alpha(1)-adrenergic, muscarinic and 1,4-DHP calcium channel antagonist receptors. We developed a novel and convenient method of determining 5alpha-reductase activity using LC/MS. With this method, SPE was shown to inhibit 5alpha-reductase activity in rat liver with an IC(50) of 101 microg/ml. Similarly, all the fatty acids except palmitic acid inhibited 5alpha-reductase activity, with IC(50) values of 42.1 to 67.6 microg/ml. In conclusion, lauric acid, oleic acid, myristic acid, and linoleic acid, major constituents of SPE, exerted binding activities of alpha(1)-adrenergic, muscarinic and 1,4-DHP receptors and inhibited 5

  17. Bile Acid Receptor Agonist GW4064 Regulates PPARγ Coactivator-1α Expression Through Estrogen Receptor-Related Receptor α

    PubMed Central

    Dwivedi, Shailendra Kumar Dhar; Singh, Nidhi; Kumari, Rashmi; Mishra, Jay Sharan; Tripathi, Sarita; Banerjee, Priyam; Shah, Priyanka; Kukshal, Vandana; Tyagi, Abdul Malik; Gaikwad, Anil Nilkanth; Chaturvedi, Rajnish Kumar; Mishra, Durga Prasad; Trivedi, Arun Kumar; Sanyal, Somali; Chattopadhyay, Naibedya; Ramachandran, Ravishankar; Siddiqi, Mohammad Imran; Bandyopadhyay, Arun; Arora, Ashish; Lundåsen, Thomas; Anakk, Sayee Priyadarshini; Moore, David D.

    2011-01-01

    Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) is induced in energy-starved conditions and is a key regulator of energy homeostasis. This makes PGC-1α an attractive therapeutic target for metabolic syndrome and diabetes. In our effort to identify new regulators of PGC-1α expression, we found that GW4064, a widely used synthetic agonist for the nuclear bile acid receptor [farnesoid X receptor (FXR)] strongly enhances PGC-1α promoter reporter activity, mRNA, and protein expression. This induction in PGC-1α concomitantly enhances mitochondrial mass and expression of several PGC-1α target genes involved in mitochondrial function. Using FXR-rich or FXR-nonexpressing cell lines and tissues, we found that this effect of GW4064 is not mediated directly by FXR but occurs via activation of estrogen receptor-related receptor α (ERRα). Cell-based, biochemical and biophysical assays indicate GW4064 as an agonist of ERR proteins. Interestingly, FXR disruption alters GW4064 induction of PGC-1α mRNA in a tissue-dependent manner. Using FXR-null [FXR knockout (FXRKO)] mice, we determined that GW4064 induction of PGC-1α expression is not affected in oxidative soleus muscles of FXRKO mice but is compromised in the FXRKO liver. Mechanistic studies to explain these differences revealed that FXR physically interacts with ERR and protects them from repression by the atypical corepressor, small heterodimer partner in liver. Together, this interplay between ERRα-FXR-PGC-1α and small heterodimer partner offers new insights into the biological functions of ERRα and FXR, thus providing a knowledge base for therapeutics in energy balance-related pathophysiology. PMID:21493670

  18. p-Coumaric acid activates the GABA-A receptor in vitro and is orally anxiolytic in vivo.

    PubMed

    Scheepens, Arjan; Bisson, Jean-Francois; Skinner, Margot

    2014-02-01

    The increasing prevalence and social burden of subclinical anxiety in the western world represents a significant psychosocial and financial cost. Consumers are favouring a more natural and nonpharmacological approach for alleviating the effects of everyday stress and anxiety. The gamma-aminobutyric acid (GABA) receptor is the primary mediator of central inhibitory neurotransmission, and GABA-receptor agonists are well known to convey anxiolytic effects. Using an in vitro screening approach to identify naturally occurring phytochemical GABA agonists, we discovered the plant secondary metabolite p-coumaric acid to have significant GABAergic activity, an effect that could be blocked by co-administration of the specific GABA-receptor antagonist, picrotoxin. Oral administration of p-coumaric acid to rodents induced a significant anxiolytic effect in vivo as measured using the elevated plus paradigm, in line with the effects of oral diazepam. Given that p-coumaric acid is reasonably well absorbed following oral consumption in man and is relatively nontoxic, it may be suitable for the formulation of a safe and effective anxiolytic functional food. Copyright © 2013 John Wiley & Sons, Ltd.

  19. Stimulation of acid secretion and phosphoinositol production by rat parietal cell muscarinic M sub 2 receptors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pfeiffer, A.; Rochlitz, H.; Herz, A.

    The muscarinic receptor system involved in hydrogen production by enriched rat gastric parietal cells was investigated. Muscarinic receptor density determined by (N-methyl-{sup 3}H)scopolamine binding was 8,100/cell. The receptor appeared to be of the M{sub 2} muscarinic receptor subtype, since it had a low affinity (K{sub d} 189 nM) for the M{sub 1} receptor antagonist pirenzepine compared with atropine. Receptor activation by carbachol rapidly augmented levels of polyphosphoinositides, indicating an activation of phospholipase C. The dose-response relations for the increase in inositol phosphates closely paralleled the binding of carbachol to muscarinic receptors. The inositol phosphate response was antagonized by pirenzepine withmore » a K{sub i} of 177 nM. the stimulation of inositol phosphate levels by carbachol correlated well with the stimulation of ({sup 14}C)aminopyrine uptake, determine as an index of acid secretion. The muscarinic agonists oxotremorine, pilocarpine, and bethanechol elicited partial increases in inositol phosphates at maximal drug concentrations, and these partial increases correlated with their ability to stimulate ({sup 14}C)aminopyrine uptake. These data indicate that inositolpolyphosphates may be a second messenger of M{sub 2} receptors stimulating acid secretion.« less

  20. The Barley Magnesium Chelatase 150-kD Subunit Is Not an Abscisic Acid Receptor1[OA

    PubMed Central

    Müller, André H.; Hansson, Mats

    2009-01-01

    Magnesium chelatase is the first unique enzyme of the chlorophyll biosynthetic pathway. It is composed of three gene products of which the largest is 150 kD. This protein was recently identified as an abscisic acid receptor in Arabidopsis (Arabidopsis thaliana). We have evaluated whether the barley (Hordeum vulgare) magnesium chelatase large subunit, XanF, could be a receptor for the phytohormone. The study involved analysis of recombinant magnesium chelatase protein as well as several induced chlorophyll-deficient magnesium chelatase mutants with defects identified at the gene and protein levels. Abscisic acid had no effect on magnesium chelatase activity and binding to the barley 150-kD protein could not be shown. Magnesium chelatase mutants showed a wild-type response in respect to postgermination growth and stomatal aperture. Our results question the function of the large magnesium chelatase subunit as an abscisic acid receptor. PMID:19176716

  1. Lack of Correlation between Aberrant p16, RAR-β2, TIMP3, ERCC1, and BRCA1 Protein Expression and Promoter Methylation in Squamous Cell Carcinoma Accompanying Candida albicans-Induced Inflammation

    PubMed Central

    Terayama, Yui; Matsuura, Tetsuro; Ozaki, Kiyokazu

    2016-01-01

    Hyperplastic candidiasis is characterized by thickening of the mucosal epithelia with Candida albicans infection with occasional progression to squamous cell carcinoma (SCC). C. albicans is a critical factor in tumor development; however, the oncogenic mechanism is unclear. We have previously produced an animal model for hyperplastic candidiasis in the rat forestomach. In the present study, we investigate whether impaired DNA methylation and associated protein expression of tumor suppressor and DNA repair genes are involved in the SCC carcinogenesis process using this hyperplastic candidiasis model. Promoter methylation and protein expression were analyzed by methylation specific PCR and immunohistochemical staining, respectively, of 5 areas in the forestomachs of alloxan-induced diabetic rats with hyperplastic candidiasis: normal squamous epithelia, squamous hyperplasia, squamous hyperplasia adjacent to SCC, squamous hyperplasia transitioning to SCC, and SCC. We observed nuclear p16 overexpression despite increases in p16 gene promoter methylation during the carcinogenic process. TIMP3 and RAR-β2 promoter methylation progressed until the precancerous stage but disappeared upon malignant transformation. In comparison, TIMP3 protein expression was suppressed during carcinogenesis and RAR-β2 expression was attenuated in the cytoplasm but enhanced in nuclei. ERCC1 and BRCA1 promoters were not methylated at any stage; however, their protein expression disappeared beginning at hyperplasia and nuclear protein re-expression in SCC was observed only for ERCC1. These results suggest that aberrant p16, RAR-β2, TIMP3, ERCC1, and BRCA1 expression might occur that is inconsistent with the respective gene promoter methylation status, and that this overexpression might serve to promote the inflammatory carcinogenesis caused by C. albicans infection. PMID:27410681

  2. Pharmacological activation of lysophosphatidic acid receptors regulates erythropoiesis

    PubMed Central

    Lin, Kuan-Hung; Ho, Ya-Hsuan; Chiang, Jui-Chung; Li, Meng-Wei; Lin, Shi-Hung; Chen, Wei-Min; Chiang, Chi-Ling; Lin, Yu-Nung; Yang, Ya-Jan; Chen, Chiung-Nien; Lu, Jenher; Huang, Chang-Jen; Tigyi, Gabor; Yao, Chao-Ling; Lee, Hsinyu

    2016-01-01

    Lysophosphatidic acid (LPA), a growth factor-like phospholipid, regulates numerous physiological functions, including cell proliferation and differentiation. In a previous study, we have demonstrated that LPA activates erythropoiesis by activating the LPA 3 receptor subtype (LPA3) under erythropoietin (EPO) induction. In the present study, we applied a pharmacological approach to further elucidate the functions of LPA receptors during red blood cell (RBC) differentiation. In K562 human erythroleukemia cells, knockdown of LPA2 enhanced erythropoiesis, whereas knockdown of LPA3 inhibited RBC differentiation. In CD34+ human hematopoietic stem cells (hHSC) and K526 cells, the LPA3 agonist 1-oleoyl-2-methyl-sn-glycero-3-phosphothionate (2S-OMPT) promoted erythropoiesis, whereas the LPA2 agonist dodecyl monophosphate (DMP) and the nonlipid specific agonist GRI977143 (GRI) suppressed this process. In zebrafish embryos, hemoglobin expression was significantly increased by 2S-OMPT treatment but was inhibited by GRI. Furthermore, GRI treatment decreased, whereas 2S-OMPT treatment increased RBC counts and amount of hemoglobin level in adult BALB/c mice. These results indicate that LPA2 and LPA3 play opposing roles during RBC differentiation. The pharmacological activation of LPA receptor subtypes represent a novel strategies for augmenting or inhibiting erythropoiesis. PMID:27244685

  3. Pharmacological activation of lysophosphatidic acid receptors regulates erythropoiesis.

    PubMed

    Lin, Kuan-Hung; Ho, Ya-Hsuan; Chiang, Jui-Chung; Li, Meng-Wei; Lin, Shi-Hung; Chen, Wei-Min; Chiang, Chi-Ling; Lin, Yu-Nung; Yang, Ya-Jan; Chen, Chiung-Nien; Lu, Jenher; Huang, Chang-Jen; Tigyi, Gabor; Yao, Chao-Ling; Lee, Hsinyu

    2016-05-31

    Lysophosphatidic acid (LPA), a growth factor-like phospholipid, regulates numerous physiological functions, including cell proliferation and differentiation. In a previous study, we have demonstrated that LPA activates erythropoiesis by activating the LPA 3 receptor subtype (LPA3) under erythropoietin (EPO) induction. In the present study, we applied a pharmacological approach to further elucidate the functions of LPA receptors during red blood cell (RBC) differentiation. In K562 human erythroleukemia cells, knockdown of LPA2 enhanced erythropoiesis, whereas knockdown of LPA3 inhibited RBC differentiation. In CD34(+) human hematopoietic stem cells (hHSC) and K526 cells, the LPA3 agonist 1-oleoyl-2-methyl-sn-glycero-3-phosphothionate (2S-OMPT) promoted erythropoiesis, whereas the LPA2 agonist dodecyl monophosphate (DMP) and the nonlipid specific agonist GRI977143 (GRI) suppressed this process. In zebrafish embryos, hemoglobin expression was significantly increased by 2S-OMPT treatment but was inhibited by GRI. Furthermore, GRI treatment decreased, whereas 2S-OMPT treatment increased RBC counts and amount of hemoglobin level in adult BALB/c mice. These results indicate that LPA2 and LPA3 play opposing roles during RBC differentiation. The pharmacological activation of LPA receptor subtypes represent a novel strategies for augmenting or inhibiting erythropoiesis.

  4. Gamma-hydroxybutyric acid (GHB) and the mesoaccumbens reward circuit: evidence for GABA(B) receptor-mediated effects.

    PubMed

    Pistis, M; Muntoni, A L; Pillolla, G; Perra, S; Cignarella, G; Melis, M; Gessa, G L

    2005-01-01

    Gamma-hydroxybutyric acid (GHB) is a short-chain fatty acid naturally occurring in the mammalian brain, which recently emerged as a major recreational drug of abuse. GHB has multiple neuronal mechanisms including activation of both the GABA(B) receptor, and a distinct GHB-specific receptor. This complex GHB-GABA(B) receptor interaction is probably responsible for the multifaceted pharmacological, behavioral and toxicological profile of GHB. Drugs of abuse exert remarkably similar effects upon reward-related circuits, in particular the mesolimbic dopaminergic system and the nucleus accumbens (NAc). We used single unit recordings in vivo from urethane-anesthetized rats to characterize the effects of GHB on evoked firing in NAc "shell" neurons and on spontaneous activity of antidromically identified dopamine (DA) cells located in the ventral tegmental area. GHB was studied in comparison with the GABA(B) receptor agonist baclofen and antagonist (2S)(+)-5,5-dimethyl-2-morpholineacetic acid (SCH50911). Additionally, we utilized a GHB analog, gamma-(p-methoxybenzil)-gamma-hydroxybutyric acid (NCS-435), devoid of GABA(B) binding properties, but with high affinity for specific GHB binding sites. In common with other drugs of abuse, GHB depressed firing in NAc neurons evoked by the stimulation of the basolateral amygdala. On DA neurons, GHB exerted heterogeneous effects, which were correlated to the baseline firing rate of the cells but led to a moderate stimulation of the DA system. All GHB actions were mediated by GABA(B) receptors, since they were blocked by SCH50911 and were not mimicked by NCS-435. Our study indicates that the electrophysiological profile of GHB is close to typical drugs of abuse: both inhibition of NAc neurons and moderate to strong stimulation of DA transmission are distinctive features of diverse classes of abused drugs. Moreover, it is concluded that addictive and rewarding properties of GHB do not necessarily involve a putative high affinity GHB

  5. Peroxisome proliferator-activated receptor-β/δ inhibits human neuroblastoma cell tumorigenesis by inducing p53- and SOX2-mediated cell differentiation.

    PubMed

    Yao, Pei-Li; Chen, Liping; Dobrzański, Tomasz P; Zhu, Bokai; Kang, Boo-Hyon; Müller, Rolf; Gonzalez, Frank J; Peters, Jeffrey M

    2017-05-01

    Neuroblastoma is a common childhood cancer typically treated by inducing differentiation with retinoic acid (RA). Peroxisome proliferator-activated receptor-β/δ, (PPARβ/δ) is known to promote terminal differentiation of many cell types. In the present study, PPARβ/δ was over-expressed in three human neuroblastoma cell lines, NGP, SK-N-BE(2), and IMR-32, that exhibit high, medium, and low sensitivity, respectively, to retinoic acid-induced differentiation to determine if PPARβ/δ and retinoic acid receptors (RARs) could be jointly targeted to increase the efficacy of treatment. All-trans-RA (atRA) decreased expression of SRY (sex determining region Y)-box 2 (SOX2), a stem cell regulator and marker of de-differentiation, in NGP and SK-N-BE(2) cells with inactive or mutant tumor suppressor p53, respectively. However, atRA did not suppress SOX2 expression in IMR-32 cells carrying wild-type p53. Over-expression and/or ligand activation of PPARβ/δ reduced the average volume and weight of ectopic tumor xenografts from NGP, SK-N-BE(2), or IMR-32 cells compared to controls. Compared with that found with atRA, PPARβ/δ suppressed SOX2 expression in NGP and SK-N-BE(2) cells and ectopic xenografts, and was also effective in suppressing SOX2 expression in IMR-32 cells that exhibit higher p53 expression compared to the former cell lines. Combined, these observations demonstrate that activating or over-expressing PPARβ/δ induces cell differentiation through p53- and SOX2-dependent signaling pathways in neuroblastoma cells and tumors. This suggests that combinatorial activation of both RARα and PPARβ/δ may be suitable as an alternative therapeutic approach for RA-resistant neuroblastoma patients. Published [2016]. This article is a U.S. Government work and is in the public domain in the USA.

  6. Retinoic acid regulates cell-shape and -death of E-FABP (FABP5)-immunoreactive septoclasts in the growth plate cartilage of mice.

    PubMed

    Bando, Yasuhiko; Yamamoto, Miyuki; Sakiyama, Koji; Sakashita, Hide; Taira, Fuyoko; Miyake, Genki; Iseki, Shoichi; Owada, Yuji; Amano, Osamu

    2017-09-01

    Septoclasts, which are mononuclear and spindle-shaped cells with many processes, have been considered to resorb the transverse septa of the growth plate (GP) cartilage at the chondro-osseous junction (COJ). We previously reported the expression of epidermal-type fatty acid-binding protein (E-FABP, FABP5) and localization of peroxisome proliferator-activated receptor (PPAR)β/δ, which mediates the cell survival or proliferation, in septoclasts. On the other hand, retinoic acid (RA) can bind to E-FABP and is stored abundantly in the GP cartilage. From these information, it is possible to hypothesize that RA in the GP is incorporated into septoclasts during the cartilage resorption and regulates the growth and/or death of septoclasts. To clarify the mechanism of the cartilage resorption induced by RA, we administered an overdose of RA or its precursor vitamin A (VA)-deficient diet to young mice. In mice of both RA excess and VA deficiency, septoclasts decreased in the number and cell size in association with shorter and lesser processes than those in normal mice, suggesting a substantial suppression of resorption by septoclasts in the GP cartilage. Lack of PPARβ/δ-expression, TUNEL reaction, RA receptor (RAR)β, and cellular retinoic acid-binding protein (CRABP)-II were induced in E-FABP-positive septoclasts under RA excess, suggesting the growth arrest/cell-death of septoclasts, whereas cartilage-derived retinoic acid-sensitive protein (CD-RAP) inducing the cell growth arrest or morphological changes was induced in septoclasts under VA deficiency. These results support and do not conflict with our hypothesis, suggesting that endogenous RA in the GP is possibly incorporated in septoclasts and utilized to regulate the activity of septoclasts resorbing the GP cartilage.

  7. Structure-based drug design targeting the cell membrane receptor GPBAR1: exploiting the bile acid scaffold towards selective agonism

    NASA Astrophysics Data System (ADS)

    di Leva, Francesco Saverio; Festa, Carmen; Renga, Barbara; Sepe, Valentina; Novellino, Ettore; Fiorucci, Stefano; Zampella, Angela; Limongelli, Vittorio

    2015-11-01

    Bile acids can regulate nutrient metabolism through the activation of the cell membrane receptor GPBAR1 and the nuclear receptor FXR. Developing an exogenous control over these receptors represents an attractive strategy for the treatment of enterohepatic and metabolic disorders. A number of dual GPBAR1/FXR agonists are known, however their therapeutic use is limited by multiple unwanted effects due to activation of the diverse downstream signals controlled by the two receptors. On the other hand, designing selective GPBAR1 and FXR agonists is challenging since the two proteins share similar structural requisites for ligand binding. Here, taking advantage of our knowledge of the two targets, we have identified through a rational drug design study a series of amine lithocholic acid derivatives as selective GPBAR1 agonists. The presence of the 3α-NH2 group on the steroidal scaffold is responsible for the selectivity over FXR unveiling unprecedented structural insights into bile acid receptors activity modulation.

  8. Discovery and Characterization of a Novel Small-Molecule Agonist for Medium-Chain Free Fatty Acid Receptor G Protein-Coupled Receptor 84.

    PubMed

    Zhang, Qing; Yang, Hui; Li, Jing; Xie, Xin

    2016-05-01

    G protein-coupled receptor 84 (GPR84) is a free fatty acid receptor activated by medium-chain free fatty acids with 9-14 carbons. It is expressed mainly in the immune-related tissues, such as spleen, bone marrow, and peripheral blood leukocytes. GPR84 plays significant roles in inflammatory processes and may represent a novel drug target for the treatment of immune-mediated diseases. However, the lack of potent and specific ligands for GPR84 hindered the study of its functions and the development of potential clinical applications. Here, we report the screen of 160,000 small-molecule compounds with a calcium mobilization assay using a human embryonic kidney 293 cell line stably expressing GPR84 and Gα16, and the identification of 2-(hexylthio)pyrimidine-4,6-diol (ZQ-16) as a potent and selective agonist of GPR84 with a novel structure. ZQ-16 activates several GPR84-mediated signaling pathways, including calcium mobilization, inhibition of cAMP accumulation, phosphorylation of extracellular signal-regulated protein kinase 1/2, receptor desensitization and internalization, and receptor-β-arrestin interaction. This compound may be a useful tool to study the functions of GPR84 and a potential candidate for further structural optimization. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  9. Agrochemical control of plant water use using engineered abscisic acid receptors.

    PubMed

    Park, Sang-Youl; Peterson, Francis C; Mosquna, Assaf; Yao, Jin; Volkman, Brian F; Cutler, Sean R

    2015-04-23

    Rising temperatures and lessening fresh water supplies are threatening agricultural productivity and have motivated efforts to improve plant water use and drought tolerance. During water deficit, plants produce elevated levels of abscisic acid (ABA), which improves water consumption and stress tolerance by controlling guard cell aperture and other protective responses. One attractive strategy for controlling water use is to develop compounds that activate ABA receptors, but agonists approved for use have yet to be developed. In principle, an engineered ABA receptor that can be activated by an existing agrochemical could achieve this goal. Here we describe a variant of the ABA receptor PYRABACTIN RESISTANCE 1 (PYR1) that possesses nanomolar sensitivity to the agrochemical mandipropamid and demonstrate its efficacy for controlling ABA responses and drought tolerance in transgenic plants. Furthermore, crystallographic studies provide a mechanistic basis for its activity and demonstrate the relative ease with which the PYR1 ligand-binding pocket can be altered to accommodate new ligands. Thus, we have successfully repurposed an agrochemical for a new application using receptor engineering. We anticipate that this strategy will be applied to other plant receptors and represents a new avenue for crop improvement.

  10. Lipoic acid stimulates cAMP production via G protein coupled receptor dependent and independent mechanisms

    PubMed Central

    Salinthone, Sonemany; Schillace, Robynn V.; Tsang, Catherine; Regan, John W.; Bourdette, Dennis N.; Carr, Daniel W.

    2010-01-01

    Lipoic acid (LA) is a naturally occurring fatty acid that exhibits anti-oxidant and anti-inflammatory properties and is being pursued as a therapeutic for many diseases including multiple sclerosis, diabetic polyneuropathy and Alzheimer’s disease. We previously reported on the novel finding that racemic LA (50:50 mixture of R and S LA) stimulates cAMP production, activates prostanoid EP2 and EP4 receptors and adenylyl cyclases (AC), and suppresses activation and cytotoxicity in NK cells. In this study we present evidence that furthers our understanding of the mechanisms of action of LA. Using various LA derivatives, dihydrolipoic acid (DHLA), S,S-dimethyl lipoic acid (DMLA) and lipoamide (LPM), we discovered that only LA is capable of stimulating cAMP production in NK cells. Furthermore, there is no difference in cAMP production after stimulation with either R-LA, S-LA or racemic LA. Competition and synergistic studies indicate that LA may also activate AC independent of the EP2 and EP4 receptors. Pretreatment of PBMCc with KH7 (a specific peptide inhibitor of soluble AC) and the calcium inhibitor (Bapta) prior to LA treatment resulted in reduced cAMP levels, suggesting that soluble AC and calcium signaling mediate LA stimulation of cAMP production. In addition, pharmacological inhibitor studies demonstrate that LA also activates other G- protein coupled receptors, including histamine and adenosine, but not the beta adrenergic receptors. These novel findings provide information to better understand the mechanisms of action of LA, which can help facilitate the use of LA as a therapeutic for various diseases. PMID:21036588

  11. Cross-calibration of Fuji TR image plate and RAR 2492 x-ray film to determine the response of a DITABIS Super Micron image plate scanner

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dunham, G., E-mail: gsdunha@sandia.gov; Harding, E. C.; Loisel, G. P.

    Fuji TR image plate is frequently used as a replacement detector medium for x-ray imaging and spectroscopy diagnostics at NIF, Omega, and Z facilities. However, the familiar Fuji BAS line of image plate scanners is no longer supported by the industry, and so a replacement scanning system is needed. While the General Electric Typhoon line of scanners could replace the Fuji systems, the shift away from photo stimulated luminescence units to 16-bit grayscale Tag Image File Format (TIFF) leaves a discontinuity when comparing data collected from both systems. For the purposes of quantitative spectroscopy, a known unit of intensity appliedmore » to the grayscale values of the TIFF is needed. The DITABIS Super Micron image plate scanning system was tested and shown to potentially rival the resolution and dynamic range of Kodak RAR 2492 x-ray film. However, the absolute sensitivity of the scanner is unknown. In this work, a methodology to cross calibrate Fuji TR image plate and the absolutely calibrated Kodak RAR 2492 x-ray film is presented. Details of the experimental configurations used are included. An energy dependent scale factor to convert Fuji TR IP scanned on a DITABIS Super Micron scanner from 16-bit grayscale TIFF to intensity units (i.e., photons per square micron) is discussed.« less

  12. Ursodeoxycholic Acid Induces Death Receptor-mediated Apoptosis in Prostate Cancer Cells

    PubMed Central

    Lee, Won Sup; Jung, Ji Hyun; Panchanathan, Radha; Yun, Jeong Won; Kim, Dong Hoon; Kim, Hye Jung; Kim, Gon Sup; Ryu, Chung Ho; Shin, Sung Chul; Hong, Soon Chan; Choi, Yung Hyun; Jung, Jin-Myung

    2017-01-01

    Background Bile acids have anti-cancer properties in a certain types of cancers. We determined anticancer activity and its underlying molecular mechanism of ursodeoxycholic acid (UDCA) in human DU145 prostate cancer cells. Methods Cell viability was measured with an MTT assay. UDCA-induced apoptosis was determined with flow cytometric analysis. The expression levels of apoptosis-related signaling proteins were examined with Western blotting. Results UDCA treatment significantly inhibited cell growth of DU145 in a dose-dependent manner. It induced cellular shrinkage and cytoplasmic blebs and accumulated the cells with sub-G1 DNA contents. Moreover, UDCA activated caspase 8, suggesting that UDCA-induced apoptosis is associated with extrinsic pathway. Consistent to this finding, UDCA increased the expressions of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor, death receptor 4 (DR4) and death receptor 5 (DR5), and TRAIL augmented the UDCA-induced cell death in DU145 cells. In addition, UDCA also increased the expressions of Bax and cytochrome c and decreased the expression of Bcl-xL in DU145 cells. This finding suggests that UDCA-induced apoptosis may be involved in intrinsic pathway. Conclusions UDCA induces apoptosis via extrinsic pathway as well as intrinsic pathway in DU145 prostate cancer cells. UDCA may be a promising anti-cancer agent against prostate cancer. PMID:28382282

  13. Molecular determinants of the olfactory receptor Olfr544 activation by azelaic acid.

    PubMed

    Thach, Trung Thanh; Hong, Yu-Jung; Lee, Sangho; Lee, Sung-Joon

    2017-04-01

    The mouse olfactory receptor Olfr544 is expressed in several non-olfactory tissues and has been suggested as a functional receptor regulating different signaling pathways. However, the molecular interaction between Olfr544 and its natural ligand, azelaic acid (AzA), remains poorly characterized, primarily due to difficulties in the heterologous expression of the receptor protein on the cell membrane and lack of entire protein structure. In this report, we describe the molecular determinants of Olfr544 activation by AzA. N-terminal lucy-flag-rho tag ensured the heterologous expression of Olfr544 on the Hana3A cell surface. Molecular modeling and docking combined with mutational analysis identified amino acid residues in the Olfr544 for the interaction with AzA. Our data demonstrated that the Y109 residue in transmembrane helix 3 forms a hydrogen bond with AzA, which is crucial for the receptor-ligand interaction and activation. Y109 is required for the Olfr544 activation by AzA which, in turn, stimulates the Olfr544-dependent CREB-PGC-1α signaling axis and is followed by the induction of mitochondrial biogenesis in Olfr544 wild-type transfected Hana3A cells, but not in mock or Y109A mutant transfected cells. Collectively, these data indicated that a hydrogen bond between Y109 residue and AzA is a major determinant of the Olfr544-AzA interaction and activation. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Unsurmountable antagonism of brain 5-hydroxytryptamine2 receptors by (+)-lysergic acid diethylamide and bromo-lysergic acid diethylamide.

    PubMed

    Burris, K D; Sanders-Bush, E

    1992-11-01

    Lysergic acid diethylamide (LSD) and its structural analogue 2-bromo-lysergic acid diethylamide (BOL) act as unsurmountable antagonists of serotonin-elicited contractions in smooth muscle preparations. Two different models, allosteric and kinetic, have been invoked to explain these findings. The present studies investigate the mechanism of antagonism of brain 5-hydroxytryptamine (5HT)2 receptors, utilizing cells transfected with 5HT2 receptor cDNA cloned from rat brain. A proximal cellular response, phosphoinositide hydrolysis, was examined in order to minimize possible postreceptor effects. Even though LSD behaved as a partial agonist and BOL as a pure antagonist, both drugs blocked the effect of serotonin in an unsurmountable manner, i.e., increasing concentrations of serotonin could not overcome the blocking effect of LSD or BOL. Radioligand binding studies showed that preincubation of membranes with either LSD or BOL reduced the density of [3H]ketanserin binding sites, suggesting that the drugs bind tightly to the 5HT2 receptor and are not displaced during the binding assay. Two additional experiments supported this hypothesis. First, the off-rate of [3H] LSD was slow (20 min), relative to that of [3H]ketanserin (approximately 4 min). Second, when the length of incubation with [3H]ketanserin was increased to 60 min, the LSD-induced decrease in Bmax was essentially eliminated. The possibility that LSD and BOL decrease [3H]ketanserin binding by interacting with an allosteric site was rejected, because neither drug altered the rate of dissociation of [3H]ketanserin. The most parsimonious interpretation of these results is that unsurmountable antagonism reflects prolonged occupancy of the receptor by slowly reversible antagonists.

  15. Insulin receptor-related receptor as an extracellular pH sensor involved in the regulation of acid-base balance.

    PubMed

    Petrenko, Alexander G; Zozulya, Sergey A; Deyev, Igor E; Eladari, Dominique

    2013-10-01

    Recent studies of insulin receptor-related receptor (IRR) revealed its unusual property to activate upon extracellular application of mildly alkaline media, pH>7.9. The activation of IRR with hydroxyl anion has typical features of ligand-receptor interaction; it is specific, dose-dependent, involves the IRR extracellular domain and is accompanied by a major conformational change. IRR is a member of the insulin receptor minifamily and has been long viewed as an orphan receptor tyrosine kinase since no peptide or protein agonist of IRR was found. In the evolution, IRR is highly conserved since its divergence from the insulin and insulin-like growth factor receptors in amphibia. The latter two cannot be activated by alkali. Another major difference between them is that unlike ubiquitously expressed insulin and insulin-like growth factor receptors, IRR is found in specific sets of cells of only some tissues, most of them being exposed to extracorporeal liquids of extreme pH. In particular, largest concentrations of IRR are in beta-intercalated cells of the kidneys. The primary physiological function of these cells is to excrete excessive alkali as bicarbonate into urine. When IRR is removed genetically, animals loose the property to excrete bicarbonate upon experimentally induced alkalosis. In this review, we will discuss the available in vitro and in vivo data that support the hypothesis of IRR role as a physiological alkali sensor that regulates acid-base balance. This article is part of a Special Issue entitled: Emerging recognition and activation mechanisms of receptor tyrosine kinases. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Inhibition of the NAD-Dependent Protein Deacetylase SIRT2 Induces Granulocytic Differentiation in Human Leukemia Cells

    PubMed Central

    Sunami, Yoshitaka; Araki, Marito; Hironaka, Yumi; Morishita, Soji; Kobayashi, Masaki; Liew, Ei Leen; Edahiro, Yoko; Tsutsui, Miyuki; Ohsaka, Akimichi; Komatsu, Norio

    2013-01-01

    Sirtuins, NAD-dependent protein deacetylases, play important roles in cellular functions such as metabolism and differentiation. Whether sirtuins function in tumorigenesis is still controversial, but sirtuins are aberrantly expressed in tumors, which may keep cancerous cells undifferentiated. Therefore, we investigated whether the inhibition of sirtuin family proteins induces cellular differentiation in leukemic cells. The sirtuin inhibitors tenovin-6 and BML-266 induce granulocytic differentiation in the acute promyelocytic leukemia (APL) cell line NB4. This differentiation is likely caused by an inhibition of SIRT2 deacetylase activity, judging from the accumulation of acetylated α-tubulin, a major SIRT2 substrate. Unlike the clinically used differentiation inducer all-trans retinoic acid, tenovin-6 shows limited effects on promyelocytic leukemia–retinoic acid receptor α (PML-RAR-α) stability and promyelocytic leukemia nuclear body formation in NB4 cells, suggesting that tenovin-6 does not directly target PML-RAR-α activity. In agreement with this, tenovin-6 induces cellular differentiation in the non-APL cell line HL-60, where PML-RAR-α does not exist. Knocking down SIRT2 by shRNA induces granulocytic differentiation in NB4 cells, which demonstrates that the inhibition of SIRT2 activity is sufficient to induce cell differentiation in NB4 cells. The overexpression of SIRT2 in NB4 cells decreases the level of granulocytic differentiation induced by tenovin-6, which indicates that tenovin-6 induces granulocytic differentiation by inhibiting SIRT2 activity. Taken together, our data suggest that targeting SIRT2 is a viable strategy to induce leukemic cell differentiation. PMID:23460888

  17. Role of amino acids in salivation and the localization of their receptors in the rat salivary gland.

    PubMed

    Shida, T; Kondo, E; Ueda, Y; Takai, N; Yoshida, Y; Araki, T; Kiyama, H; Tohyama, M

    1995-11-01

    The distribution of gamma-aminobutyric acid (GABA) receptor subunits such as GABAAR-gamma 1 and GABAAR-gamma 2, and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) type receptor subunits such as GluR-1, GluR-2/3 and GluR-4, and N-methyl-D-aspartic acid (NMDA) type subunits such as NR1 were investigated by immunocytochemistry. Furthermore, the roles of these amino acids, GABA and glutamate, on salivation were analyzed in the rat submandibular and sublingual glands. Some similarities were observed in the distribution patterns of GABAA type receptors and AMPA receptors. In the submandibular ganglion cells, collecting ducts and striated ducts, these subunits were expressed strongly; however, there were some differences in their expression patterns between the submandibular and sublingual gland acinar cells. Since these receptor subunits were expressed in the acinar cell bodies of the submandibular gland, they were not expressed in the acinar cells but were expressed in the myoepithelial cells in the sublingual gland. On the other hand, no NR1 expression was observed. To examine the roles of GABA and glutamate in salivation, the submandibular and sublingual glands were perfused partially with Ringer's solution via a facial artery to avoid systemic influence, and substrates were infused into the perfusion solution. No salivary secretion was evoked by GABA or glutamate infusion in the absence of electrical stimulation (2-3 V, 5 ms, 20 Hz). Salivary flow evoked by electrical stimulation of the chorda-lingual nerve caused significant inhibition by GABA (10(-6), 10(-5), 10(-4) and 10(-3) M) and the GABAAR agonist muscimol 10(-3) and 10(-6) M) (n = 6, P < 0.05). Such GABA-induced inhibition was antagonized by the GABAAR antagonists bicuculline (BCC; 10(-6) and 10(-3) M) and picrotoxin (PTX; 10(-6) and 10(-3) M). On the other hand, salivary flow evoked by electrical stimulation (8-10 V, 5 ms, 20 Hz) of the superior cervical ganglion (SCG) was not affected by

  18. Structure-activity relationships and mechanism of action of Eph-ephrin antagonists: interaction of cholanic acid with the EphA2 receptor

    PubMed Central

    Tognolini, Massimiliano; Incerti, Matteo; Mohamed, Iftiin Hassan; Giorgio, Carmine; Russo, Simonetta; Bruni, Renato; Lelli, Barbara; Bracci, Luisa; Noberini, Roberta; Pasquale, Elena B.; Barocelli, Elisabetta; Vicini, Paola; Mor, Marco

    2012-01-01

    The Eph–ephrin system, including the EphA2 receptor and the ephrin-A1 ligand, plays a critical role in tumor and vascular functions during carcinogenesis. We previously identified (3α,5β)-3-hydroxycholan-24-oic acid (lithocholic acid) as an Eph-ephrin antagonist able to inhibit EphA2 receptor activation and therefore potentially useful as a novel EphA2 receptor targeting agent. Here, we explore the structure-activity relationships of a focused set of lithocholic acid derivatives, based on molecular modelling investigation and displacement binding assays. Our exploration shows that while the 3-α-hydroxyl group of lithocholic acid has a negligible role in the recognition of the EphA2 receptor, its carboxylate group is critical for disrupting the binding of ephrin-A1 to the EphA2. As a result of our investigation, we identified (5β)-cholan-24-oic acid (cholanic acid) as a novel compound that competitively inhibits EphA2-ephrin-A1 interaction with higher potency than lithocholic acid. Surface plasmon resonance analysis indicates that cholanic acid binds specifically and reversibly to the ligand-binding domain of EphA2, with a steady-state dissociation constant (KD) in the low micromolar range. Furthermore, cholanic acid blocks the phosphorylation of EphA2 and cell retraction and rounding in PC3 prostate cancer cells, two effects that depend on EphA2 activation by the ephrin-A1 ligand. These findings suggest that cholanic acid can be used as a template structure to design effective EphA2 antagonists, with potential impact in the elucidation of the role played by this receptor in pathological conditions. PMID:22529030

  19. Salicylic acid receptors activate jasmonic acid signalling through a non-canonical pathway to promote effector-triggered immunity.

    PubMed

    Liu, Lijing; Sonbol, Fathi-Mohamed; Huot, Bethany; Gu, Yangnan; Withers, John; Mwimba, Musoki; Yao, Jian; He, Sheng Yang; Dong, Xinnian

    2016-10-11

    It is an apparent conundrum how plants evolved effector-triggered immunity (ETI), involving programmed cell death (PCD), as a major defence mechanism against biotrophic pathogens, because ETI-associated PCD could leave them vulnerable to necrotrophic pathogens that thrive on dead host cells. Interestingly, during ETI, the normally antagonistic defence hormones, salicylic acid (SA) and jasmonic acid (JA) associated with defence against biotrophs and necrotrophs respectively, both accumulate to high levels. In this study, we made the surprising finding that JA is a positive regulator of RPS2-mediated ETI. Early induction of JA-responsive genes and de novo JA synthesis following SA accumulation is activated through the SA receptors NPR3 and NPR4, instead of the JA receptor COI1. We provide evidence that NPR3 and NPR4 may mediate this effect by promoting degradation of the JA transcriptional repressor JAZs. This unique interplay between SA and JA offers a possible explanation of how plants can mount defence against a biotrophic pathogen without becoming vulnerable to necrotrophic pathogens.

  20. Channel opening of gamma-aminobutyric acid receptor from rat brain: molecular mechanisms of the receptor responses.

    PubMed

    Cash, D J; Subbarao, K

    1987-12-01

    The function of gamma-aminobutyric acid (GABA) receptors, which mediate transmembrane chloride flux, can be studied by use of 36Cl- isotope tracer with membrane from mammalian brain by quench-flow technique, with reaction times that allow resolution of the receptor desensitization rates from the ion flux rates. The rates of chloride exchange into the vesicles in the absence and presence of GABA were characterized with membrane from rat cerebral cortex. Unspecific 36Cl- influx was completed in three phases of ca. 3% (t 1/2 = 0.6 s), 56% (t 1/2 = 82 s), and 41% (t 1/2 = 23 min). GABA-mediated, specific chloride exchange occurred with 6.5% of the total vesicular internal volume. The GABA-dependent 36Cl- influx proceeded in two phases, each progressively slowed by desensitization. The measurements supported the presence of two distinguishable active GABA receptors on the same membrane mediating chloride exchange into the vesicles with initial first-order rate constants of 9.5 s-1 and 2.3 s-1 and desensitizing with first-order rate constants of 21 s-1 and 1.4 s-1, respectively, at saturation. The half-response concentrations were similar for both receptors, 150 microM and 114 microM GABA for desensitization and 105 microM and 82 microM for chloride exchange, for the faster and slower desensitizing receptors, respectively. The two receptors were present in the activity ratio of ca. 4/1, similar to the ratio of "low-affinity" to "high-affinity" GABA sites found in ligand binding experiments. The desensitization rates have a different dependence on GABA concentration than the channel-opening equilibria.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Postprandial fatty acid uptake and adipocyte remodeling in angiotensin type 2 receptor-deficient mice fed a high-fat/high-fructose diet

    PubMed Central

    Noll, Christophe; Labbé, Sébastien M.; Pinard, Sandra; Shum, Michael; Bilodeau, Lyne; Chouinard, Lucie; Phoenix, Serge; Lecomte, Roger; Carpentier, André C.; Gallo-Payet, Nicole

    2016-01-01

    ABSTRACT The role of the angiotensin type-2 receptor in adipose physiology remains controversial. The aim of the present study was to demonstrate whether genetic angiotensin type-2 receptor-deficiency prevents or worsens metabolic and adipose tissue morphometric changes observed following a 6-week high-fat/high-fructose diet with injection of a small dose of streptozotocin. We compared tissue uptake of nonesterified fatty acid and dietary fatty acid in wild-type and angiotensin type-2 receptor-deficient mice by using the radiotracer 14(R,S)-[18F]-fluoro-6-thia-heptadecanoic acid in mice fed a standard or high-fat diet. Postprandial fatty acid uptake in the heart, liver, skeletal muscle, kidney and adipose tissue was increased in wild-type mice after a high-fat diet and in angiotensin type-2 receptor-deficient mice on both standard and high-fat diets. Compared to the wild-type mice, angiotensin type-2 receptor-deficient mice had a lower body weight, an increase in fasting blood glucose and a decrease in plasma insulin and leptin levels. Mice fed a high-fat diet exhibited increased adipocyte size that was prevented by angiotensin type-2 receptor-deficiency. Angiotensin type-2 receptor-deficiency abolished the early hypertrophic adipocyte remodeling induced by a high-fat diet. The small size of adipocytes in the angiotensin type-2 receptor-deficient mice reflects their inability to store lipids and explains the increase in fatty acid uptake in non-adipose tissues. In conclusion, a genetic deletion of the angiotensin type-2 receptor is associated with metabolic dysfunction of white adipose depots, and indicates that adipocyte remodeling occurs before the onset of insulin resistance in the high-fat fed mouse model. PMID:27144096

  2. Mercaptoacetate and fatty acids exert direct and antagonistic effects on nodose neurons via GPR40 fatty acid receptors.

    PubMed

    Darling, Rebecca A; Zhao, Huan; Kinch, Dallas; Li, Ai-Jun; Simasko, Steven M; Ritter, Sue

    2014-07-01

    β-mercaptoacetate (MA) is a drug known to block mitochondrial oxidation of medium- and long-chain fatty acids (FAs) and to stimulate feeding. Because MA-induced feeding is vagally dependent, it has been assumed that the feeding response is mediated by MA's antimetabolic action at a peripheral, vagally innervated site. However, MA's site of action has not yet been identified. Therefore, we used fluorescent calcium measurements in isolated neurons from rat nodose ganglia to determine whether MA has direct effects on vagal sensory neurons. We found that MA alone did not alter cytosolic calcium concentrations in nodose neurons. However, MA (60 μM to 6 mM) significantly decreased calcium responses to both linoleic acid (LA; 10 μM) and caprylic acid (C8; 10 μM) in all neurons responsive to LA and C8. GW9508 (40 μM), an agonist of the FA receptor, G protein-coupled receptor 40 (GPR40), also increased calcium levels almost exclusively in FA-responsive neurons. MA significantly inhibited this response to GW9508. MA did not inhibit calcium responses to serotonin, high K(+), or capsaicin, which do not utilize GPRs, or to CCK, which acts on a different GPR. GPR40 was detected in nodose ganglia by RT-PCR. Results suggest that FAs directly activate vagal sensory neurons via GPR40 and that MA antagonizes this effect. Thus, we propose that MA's nonmetabolic actions on GPR40 membrane receptors, expressed by multiple peripheral tissues in addition to the vagus nerve, may contribute to or mediate MA-induced stimulation of feeding. Copyright © 2014 the American Physiological Society.

  3. Fatty Acid Amide Hydrolase (FAAH) Inhibition Enhances Memory Acquisition through Activation of PPAR-alpha Nuclear Receptors

    ERIC Educational Resources Information Center

    Mazzola, Carmen; Medalie, Julie; Scherma, Maria; Panlilio, Leigh V.; Solinas, Marcello; Tanda, Gianluigi; Drago, Filippo; Cadet, Jean Lud; Goldberg, Steven R.; Yasar, Sevil

    2009-01-01

    Inhibitors of fatty acid amide hydrolase (FAAH) increase endogenous levels of anandamide (a cannabinoid CB[subscript 1]-receptor ligand) and oleoylethanolamide and palmitoylethanolamide (OEA and PEA, ligands for alpha-type peroxisome proliferator-activated nuclear receptors, PPAR-alpha) when and where they are naturally released in the brain.…

  4. Identification of insulin as a novel retinoic acid receptor-related orphan receptor α target gene.

    PubMed

    Kuang, Jiangying; Hou, Xiaoming; Zhang, Jinlong; Chen, Yulong; Su, Zhiguang

    2014-03-18

    Insulin plays an important role in regulation of lipid and glucose metabolism. Retinoic acid receptor-related orphan receptor α (RORα) modulates physiopathological processes such as dyslipidemia and diabetes. In this study, we found overexpression of RORα in INS1 cells resulted in increased expression and secretion of insulin. Suppression of endogenous RORα caused a decrease of insulin expression. Luciferase and electrophoretic mobility shift assay (EMSA) assays demonstrated that RORα activated insulin transcription via direct binding to its promoter. RORα was also observed to regulate BETA2 expression, which is one of the insulin active transfactors. In vivo analyses showed that the insulin transcription is increased by the synthetic RORα agonist SR1078. These findings identify RORα as a transcriptional activator of insulin and suggest novel therapeutic opportunities for management of the disease. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  5. Expression of fatty acid sensing G-protein coupled receptors in peripartal Holstein cows.

    PubMed

    Agrawal, Alea; Alharthi, Abdulrahman; Vailati-Riboni, Mario; Zhou, Zheng; Loor, Juan J

    2017-01-01

    G-protein coupled receptors (GPCR), also referred as Free Fatty Acid Receptors (FFAR), are widely studied within human medicine as drug targets for metabolic disorders. To combat metabolic disorders prevalent in dairy cows during the transition period, which co-occur with negative energy balance and changes to lipid and glucose metabolism, it may be helpful to identify locations and roles of FFAR and other members of the GPCR family in bovine tissues. Quantitative RT-PCR (qPCR) of subcutaneous adipose, liver, and PMNL samples during the transition period (-10, +7, and +20 or +30 d) were used for expression profiling of medium- (MCFA) and long-chain fatty acid (LCFA) receptors GPR120 and GPR40 , MCFA receptor GPR84 , and niacin receptor HCAR2/3 . Adipose samples were obtained from cows with either high (HI; BCS ≥ 3.75) or low (LO; BCS ≤ 3.25) body condition score (BCS) to examine whether FFAR expression is correlated with this indicator of health and body reserves. Supplementation of rumen-protected methionine (MET), which may improve immune function and production postpartum, was also compared with unsupplemented control (CON) cows for liver and blood polymorphonuclear leukocytes (PMNL) samples. In adipose tissue, GPR84 and GPR120 were differentially expressed over time, while GPR40 was not expressed; in PMNL, GPR40 was differentially expressed over time and between MET vs. CON, GPR84 expression differed only between dietary groups, and GPR120 was not expressed; in liver, GPCR were either not expressed or barely detectable. The data indicate that there is likely not a direct role in liver for the selected GPCR during the transition period, but they do play variable roles in adipose and PMN. In future, these receptors may prove useful targets and/or markers for peripartal metabolism and immunity.

  6. Regulation of antibacterial defense in the small intestine by the nuclear bile acid receptor.

    PubMed

    Inagaki, Takeshi; Moschetta, Antonio; Lee, Youn-Kyoung; Peng, Li; Zhao, Guixiang; Downes, Michael; Yu, Ruth T; Shelton, John M; Richardson, James A; Repa, Joyce J; Mangelsdorf, David J; Kliewer, Steven A

    2006-03-07

    Obstruction of bile flow results in bacterial proliferation and mucosal injury in the small intestine that can lead to the translocation of bacteria across the epithelial barrier and systemic infection. These adverse effects of biliary obstruction can be inhibited by administration of bile acids. Here we show that the farnesoid X receptor (FXR), a nuclear receptor for bile acids, induces genes involved in enteroprotection and inhibits bacterial overgrowth and mucosal injury in ileum caused by bile duct ligation. Mice lacking FXR have increased ileal levels of bacteria and a compromised epithelial barrier. These findings reveal a central role for FXR in protecting the distal small intestine from bacterial invasion and suggest that FXR agonists may prevent epithelial deterioration and bacterial translocation in patients with impaired bile flow.

  7. Periodic variation in bile acids controls circadian changes in uric acid via regulation of xanthine oxidase by the orphan nuclear receptor PPARα.

    PubMed

    Kanemitsu, Takumi; Tsurudome, Yuya; Kusunose, Naoki; Oda, Masayuki; Matsunaga, Naoya; Koyanagi, Satoru; Ohdo, Shigehiro

    2017-12-29

    Xanthine oxidase (XOD), also known as xanthine dehydrogenase, is a rate-limiting enzyme in purine nucleotide degradation, which produces uric acid. Uric acid concentrations in the blood and liver exhibit circadian oscillations in both humans and rodents; however, the underlying mechanisms remain unclear. Here, we demonstrate that XOD expression and enzymatic activity exhibit circadian oscillations in the mouse liver. We found that the orphan nuclear receptor peroxisome proliferator-activated receptor-α (PPARα) transcriptionally activated the mouse XOD gene and that bile acids suppressed XOD transactivation. The synthesis of bile acids is known to be under the control of the circadian clock, and we observed that the time-dependent accumulation of bile acids in hepatic cells interfered with the recruitment of the co-transcriptional activator p300 to PPARα, thereby repressing XOD expression. This time-dependent suppression of PPARα-mediated transactivation by bile acids caused an oscillation in the hepatic expression of XOD, which, in turn, led to circadian alterations in uric acid production. Finally, we also demonstrated that the anti-hyperuricemic effect of the XOD inhibitor febuxostat was enhanced by administering it at the time of day before hepatic XOD activity increased. These results suggest an underlying mechanism for the circadian alterations in uric acid production and also underscore the importance of selecting an appropriate time of day for administering XOD inhibitors. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. The distribution of excitatory amino acid receptors on acutely dissociated dorsal horn neurons from postnatal rats.

    PubMed

    Arancio, O; Yoshimura, M; Murase, K; MacDermott, A B

    1993-01-01

    Excitatory amino acid receptor distribution was mapped on acutely dissociated neurons from postnatal rat spinal cord dorsal horn. N-methyl D-aspartate, quisqualate and kainate were applied to multiple locations along the somal and dendritic surfaces of voltage-clamped neurons by means of a pressure application system. To partially compensate for the decrement of response amplitude due to current loss between the site of activation on the dendrite and the recording electrode at the soma, a solution containing 0.15 M KCl was applied on the cell bodies and dendrites of some cells to estimate an empirical length constant. In the majority of the cells tested, the dendritic membrane had regions of higher sensitivity to excitatory amino acid agonists than the somatic membrane, with dendritic response amplitudes reaching more than seven times those at the cell body. A comparison of the relative changes in sensitivity between each combination of two of the three excitatory amino acid agonists along the same dendrite showed different patterns of agonist sensitivity along the dendrite in the majority of the cells. These data were obtained from dorsal horn neurons that had developed and formed synaptic connections in vivo. They demonstrate that in contrast to observations made on ventral horn neurons, receptor density for all the excitatory amino acid receptors on dorsal horn neurons, including the N-methyl-D-aspartate receptor, are generally higher on the dendrites than on the soma. Further, these results are similar to those obtained from dorsal horn neurons grown in culture.

  9. Nuclear hormone receptor NHR-49 controls fat consumption and fatty acid composition in C. elegans.

    PubMed

    Van Gilst, Marc R; Hadjivassiliou, Haralambos; Jolly, Amber; Yamamoto, Keith R

    2005-02-01

    Mammalian nuclear hormone receptors (NHRs), such as liver X receptor, farnesoid X receptor, and peroxisome proliferator-activated receptors (PPARs), precisely control energy metabolism. Consequently, these receptors are important targets for the treatment of metabolic diseases, including diabetes and obesity. A thorough understanding of NHR fat regulatory networks has been limited, however, by a lack of genetically tractable experimental systems. Here we show that deletion of the Caenorhabditis elegans NHR gene nhr-49 yielded worms with elevated fat content and shortened life span. Employing a quantitative RT-PCR screen, we found that nhr-49 influenced the expression of 13 genes involved in energy metabolism. Indeed, nhr-49 served as a key regulator of fat usage, modulating pathways that control the consumption of fat and maintain a normal balance of fatty acid saturation. We found that the two phenotypes of the nhr-49 knockout were linked to distinct pathways and were separable: The high-fat phenotype was due to reduced expression of enzymes in fatty acid beta-oxidation, and the shortened adult life span resulted from impaired expression of a stearoyl-CoA desaturase. Despite its sequence relationship with the mammalian hepatocyte nuclear factor 4 receptor, the biological activities of nhr-49 were most similar to those of the mammalian PPARs, implying an evolutionarily conserved role for NHRs in modulating fat consumption and composition. Our findings in C. elegans provide novel insights into how NHR regulatory networks are coordinated to govern fat metabolism.

  10. Role of free fatty acid receptors in the regulation of energy metabolism.

    PubMed

    Hara, Takafumi; Kashihara, Daiji; Ichimura, Atsuhiko; Kimura, Ikuo; Tsujimoto, Gozoh; Hirasawa, Akira

    2014-09-01

    Free fatty acids (FFAs) are energy-generating nutrients that act as signaling molecules in various cellular processes. Several orphan G protein-coupled receptors (GPCRs) that act as FFA receptors (FFARs) have been identified and play important physiological roles in various diseases. FFA ligands are obtained from food sources and metabolites produced during digestion and lipase degradation of triglyceride stores. FFARs can be grouped according to ligand profiles, depending on the length of carbon chains of the FFAs. Medium- and long-chain FFAs activate FFA1/GPR40 and FFA4/GPR120. Short-chain FFAs activate FFA2/GPR43 and FFA3/GPR41. However, only medium-chain FFAs, and not long-chain FFAs, activate GPR84 receptor. A number of pharmacological and physiological studies have shown that these receptors are expressed in various tissues and are primarily involved in energy metabolism. Because an impairment of these processes is a part of the pathology of obesity and type 2 diabetes, FFARs are considered as key therapeutic targets. Here, we reviewed recently published studies on the physiological functions of these receptors, primarily focusing on energy homeostasis. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. A gate-latch-lock mechanism for hormone signalling by abscisic acid receptors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Melcher, Karsten; Ng, Ley-Moy; Zhou, X Edward

    2010-01-12

    Abscisic acid (ABA) is a ubiquitous hormone that regulates plant growth, development and responses to environmental stresses. Its action is mediated by the PYR/PYL/RCAR family of START proteins, but it remains unclear how these receptors bind ABA and, in turn, how hormone binding leads to inhibition of the downstream type 2C protein phosphatase (PP2C) effectors. Here we report crystal structures of apo and ABA-bound receptors as well as a ternary PYL2-ABA-PP2C complex. The apo receptors contain an open ligand-binding pocket flanked by a gate that closes in response to ABA by way of conformational changes in two highly conserved β-loopsmore » that serve as a gate and latch. Moreover, ABA-induced closure of the gate creates a surface that enables the receptor to dock into and competitively inhibit the PP2C active site. A conserved tryptophan in the PP2C inserts directly between the gate and latch, which functions to further lock the receptor in a closed conformation. Together, our results identify a conserved gate-latch-lock mechanism underlying ABA signalling.« less

  12. Efficient Receptor Mediated siRNA Delivery in Vitro by Folic Acid Targeted Pentablock Copolymer-Based Micelleplexes.

    PubMed

    Lehner, Roman; Liu, Kegang; Wang, Xueya; Hunziker, Patrick

    2017-08-14

    Novel, biocompatible polyplexes, based on the combination of cationic pentablock copolymers with folic acid functionalized copolymers, were designed and developed for target-specific siRNA delivery. The resulting micelleplexes spontaneously formed polymeric micelles with a hydrophobic core surrounded directly by a cationic poly-2-(4-aminobutyl)-oxazole (PABOXA) and subsequently shielded by hydrophilic poly-2-methyl-oxazole (PMOXA) layer. The described micelleplexes form highly stable particles even in complete serum after 24 h compared with the highly cationic polymer PEI, which show aggregate formation in serum containing buffer solution. Targeted siRNA delivery and gene knockdown could be shown using green fluorescent protein (GFP) expressing HeLa cells, resulting in ∼31% and ∼8% suppression of the expression of GFP for targeted and nontargeted micelleplexes, respectively. Comparison studies of folic-receptor positive HeLa cells with normal folic-receptor-negative HEK293 cells revealed involvement of receptor mediated cellular uptake of fluorescently labeled siRNA. The new designed nanocarrier showed no cytotoxicity, having a potential application. The presented concept of shielding a nucleic-acid complexing cationic chains with a stealth layer and combining it with receptor ligand overcomes typical problems with undesired protein and cell interactions in delivery of nucleic acids using polymeric systems, opening new doors for application if RNA inhibition in the organism.

  13. Valerian extract and valerenic acid are partial agonists of the 5-HT5a receptor in vitro.

    PubMed

    Dietz, Birgit M; Mahady, Gail B; Pauli, Guido F; Farnsworth, Norman R

    2005-08-18

    Insomnia is the most frequently encountered sleep complaint worldwide. While many prescription drugs are used to treat insomnia, extracts of valerian (Valeriana officinalis L., Valerianaceae) are also used for the treatment of insomnia and restlessness. To determine novel mechanisms of action, radioligand binding studies were performed with valerian extracts (100% methanol, 50% methanol, dichloromethane [DCM], and petroleum ether [PE]) at the melatonin, glutamate, and GABA(A) receptors, and 8 serotonin receptor subtypes. Both DCM and PE extracts had strong binding affinity to the 5-HT(5a) receptor, but only weak binding affinity to the 5-HT(2b) and the serotonin transporter. Subsequent binding studies focused on the 5-HT(5a) receptor due to the distribution of this receptor in the suprachiasmatic nucleus of the brain, which is implicated in the sleep-wake cycle. The PE extract inhibited [(3)H]lysergic acid diethylamide (LSD) binding to the human 5-HT(5a) receptor (86% at 50 microg/ml) and the DCM extract inhibited LSD binding by 51%. Generation of an IC(50) curve for the PE extract produced a biphasic curve, thus GTP shift experiments were also performed. In the absence of GTP, the competition curve was biphasic (two affinity sites) with an IC(50) of 15.7 ng/ml for the high-affinity state and 27.7 microg/ml for the low-affinity state. The addition of GTP (100 microM) resulted in a right-hand shift of the binding curve with an IC(50) of 11.4 microg/ml. Valerenic acid, the active constituent of both extracts, had an IC(50) of 17.2 microM. These results indicate that valerian and valerenic acid are new partial agonists of the 5-HT(5a) receptor.

  14. Valerian extract and valerenic acid are partial agonists of the 5-HT5a receptor in vitro

    PubMed Central

    Dietz, Birgit M.; Mahady, Gail B.; Pauli, Guido F.; Farnsworth, Norman R.

    2018-01-01

    Insomnia is the most frequently encountered sleep complaint worldwide. While many prescription drugs are used to treat insomnia, extracts of valerian (Valeriana officinalis L., Valerianaceae) are also used for the treatment of insomnia and restlessness. To determine novel mechanisms of action, radioligand binding studies were performed with valerian extracts (100% methanol, 50% methanol, dichloromethane [DCM], and petroleum ether [PE]) at the melatonin, glutamate, and GABAA receptors, and 8 serotonin receptor subtypes. Both DCM and PE extracts had strong binding affinity to the 5-HT5a receptor, but only weak binding affinity to the 5-HT2b and the serotonin transporter. Subsequent binding studies focused on the 5-HT5a receptor due to the distribution of this receptor in the suprachiasmatic nucleus of the brain, which is implicated in the sleep–wake cycle. The PE extract inhibited [3H]lysergic acid diethylamide (LSD) binding to the human 5-HT5a receptor (86% at 50 μg/ml) and the DCM extract inhibited LSD binding by 51%. Generation of an IC50 curve for the PE extract produced a biphasic curve, thus GTP shift experiments were also performed. In the absence of GTP, the competition curve was biphasic (two affinity sites) with an IC50 of 15.7 ng/ml for the high-affinity state and 27.7 μg/ml for the low-affinity state. The addition of GTP (100 AM) resulted in a right-hand shift of the binding curve with an IC50 of 11.4 μg/ml. Valerenic acid, the active constituent of both extracts, had an IC50 of 17.2 AM. These results indicate that valerian and valerenic acid are new partial agonists of the 5-HT5a receptor. PMID:15921820

  15. Discovery of a Novel Series of CRTH2 (DP2) Receptor Antagonists Devoid of Carboxylic Acids

    PubMed Central

    2011-01-01

    Antagonism of the CRTH2 receptor represents a very attractive target for a variety of allergic diseases. Most CRTH2 antagonists known to date possess a carboxylic acid moiety, which is essential for binding. However, potential acid metabolites O-acyl glucuronides might be linked to idiosynchratic toxicity in humans. In this communication, we describe a new series of compounds that lack the carboxylic acid moiety. Compounds with high affinity (Ki < 10 nM) for the receptor have been identified. Subsequent optimization succeeded in reducing the high metabolic clearance of the first compounds in human and rat liver microsomes. At the same time, inhibition of the CYP isoforms was optimized, giving rise to stable compounds with an acceptable CYP inhibition profile (IC50 CYP2C9 and 2C19 > 1 μM). Taken together, these data show that compounds devoid of carboxylic acid groups could represent an interesting alternative to current CRTH2 antagonists in development. PMID:24900284

  16. Expression of functional receptors by the human γ-aminobutyric acid A γ2 subunit

    PubMed Central

    Martínez-Torres, Ataúlfo; Miledi, Ricardo

    2004-01-01

    γ-Aminobutyric acid A (GABAA) receptors are heteromeric membrane proteins formed mainly by various combinations of α, β, and γ subunits; and it is commonly thought that the γ2 subunit alone does not form functional receptors. In contrast, we found that cDNA encoding the γ2L subunit of the human GABAA receptor, injected alone into Xenopus oocytes, expressed functional GABA receptors whose properties were investigated by using the two-microelectrode voltage-clamp technique. GABA elicited desensitizing membrane currents that recovered after a few minutes' wash. Repetitive applications of GABA induced a “run-up” of GABA currents that nearly doubled the amplitude of the first response. The GABA currents inverted direction at about -30 mV, indicating that they are carried mainly by Cl- ions. The homomeric γ2L receptors were also activated by β-alanine > taurine > glycine, and, like some types of heteromeric GABAA receptors, the γ2L receptors were blocked by bicuculline and were potentiated by pentobarbital and flunitrazepam. These results indicate that the human γ2L subunit is capable of forming fully functional GABA receptors by itself in Xenopus oocytes and suggest that the roles proposed for the various subunits that make up the heteromeric GABAA receptors in situ require further clarification. PMID:14981251

  17. The short-chain fatty acid receptor, FFA2, contributes to gestational glucose homeostasis.

    PubMed

    Fuller, Miles; Priyadarshini, Medha; Gibbons, Sean M; Angueira, Anthony R; Brodsky, Michael; Hayes, M Geoffrey; Kovatcheva-Datchary, Petia; Bäckhed, Fredrik; Gilbert, Jack A; Lowe, William L; Layden, Brian T

    2015-11-15

    The structure of the human gastrointestinal microbiota can change during pregnancy, which may influence gestational metabolism; however, a mechanism of action remains unclear. Here we observed that in wild-type (WT) mice the relative abundance of Actinobacteria and Bacteroidetes increased during pregnancy. Along with these changes, short-chain fatty acids (SCFAs), which are mainly produced through gut microbiota fermentation, significantly changed in both the cecum and peripheral blood throughout gestation in these mice. SCFAs are recognized by G protein-coupled receptors (GPCRs) such as free fatty acid receptor-2 (FFA2), and we have previously demonstrated that the fatty acid receptor-2 gene (Ffar2) expression is higher in pancreatic islets during pregnancy. Using female Ffar2-/- mice, we explored the physiological relevance of signaling through this GPCR and found that Ffar2-deficient female mice developed fasting hyperglycemia and impaired glucose tolerance in the setting of impaired insulin secretion compared with WT mice during, but not before, pregnancy. Insulin tolerance tests were similar in Ffar2-/- and WT mice before and during pregnancy. Next, we examined the role of FFA2 in gestational β-cell mass, observing that Ffar2-/- mice had diminished gestational expansion of β-cells during pregnancy. Interestingly, mouse genotype had no significant impact on the composition of the gut microbiome, but did affect the observed SCFA profiles, suggesting a functional difference in the microbiota. Together, these results suggest a potential link between increased Ffar2 expression in islets and the alteration of circulating SCFA levels, possibly explaining how changes in the gut microbiome contribute to gestational glucose homeostasis.

  18. Effects of rumenic acid rich conjugated linoleic acid supplementation on cognitive function and handgrip performance in older men and women.

    PubMed

    Jenkins, Nathaniel D M; Housh, Terry J; Miramonti, Amelia A; McKay, Brianna D; Yeo, Noelle M; Smith, Cory M; Hill, Ethan C; Cochrane, Kristen C; Cramer, Joel T

    2016-11-01

    The purpose of this study was to investigate the effects of 8weeks at 6g per day of RAR CLA versus placebo on cognitive function and handgrip performance in older men and women. Sixty-five (43 women, 22 men) participants (mean±SD; age=72.4±5.9yrs; BMI=26.6±4.2kg·m -2 ) were randomly assigned to a RAR CLA (n=30: 10 men, 20 women) or placebo (PLA; high oleic sunflower oil; n=35: 12 men, 23 women) group in double-blind fashion and consumed 6g·d -1 of their allocated supplement for 8weeks. Before (Visit 1) and after supplementation (Visit 2), subjects completed the Serial Sevens Subtraction Test (S 7 ), Trail Making Test Part A (TM A ) and Part B (TM B ), and Rey's Auditory Verbal Learning Test (RAVLT) to measure cognitive function. The RAVLT included 5, 15-item auditory word recalls (R 1-5 ), an interference word recall (R B ), a 6th word recall (R 6 ), and a 15-item visual word recognition trial (R R ). For handgrip performance, subjects completed maximal voluntary isometric handgrip strength (MVIC) testing before (MVIC PRE ) and after (MVIC POST ) a handgrip fatigue test at 50% MVIC PRE . Hand joint discomfort was measured during MVIC PRE , MVIC POST , and the handgrip fatigue test. There were no treatment differences (p>0.05) for handgrip strength, handgrip fatigue, or cognitive function as measured by the Trail Making Test and Serial Seven's Subtraction Test in men or women. However, RAR CLA supplementation improved cognitive function as indicated by the RAVLT R 5 in men. A qualitative examination of the mean change scores suggested that, compared to PLA, RAR CLA supplementation was associated with a small improvement in joint discomfort in both men and women. Longer-term studies are needed to more fully understand the potential impact of RAR CLA on cognitive function and hand joint discomfort in older adults, particularly in those with lower cognitive function. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Optical control of trimeric P2X receptors and acid-sensing ion channels.

    PubMed

    Browne, Liam E; Nunes, João P M; Sim, Joan A; Chudasama, Vijay; Bragg, Laricia; Caddick, Stephen; North, R Alan

    2014-01-07

    P2X receptors are trimeric membrane proteins that function as ion channels gated by extracellular ATP. We have engineered a P2X2 receptor that opens within milliseconds by irradiation at 440 nm, and rapidly closes at 360 nm. This requires bridging receptor subunits via covalent attachment of 4,4'-bis(maleimido)azobenzene to a cysteine residue (P329C) introduced into each second transmembrane domain. The cis-trans isomerization of the azobenzene pushes apart the outer ends of the transmembrane helices and opens the channel in a light-dependent manner. Light-activated channels exhibited similar unitary currents, rectification, calcium permeability, and dye uptake as P2X2 receptors activated by ATP. P2X3 receptors with an equivalent mutation (P320C) were also light sensitive after chemical modification. They showed typical rapid desensitization, and they could coassemble with native P2X2 subunits in pheochromocytoma cells to form light-activated heteromeric P2X2/3 receptors. A similar approach was used to open and close human acid-sensing ion channels (ASICs), which are also trimers but are unrelated in sequence to P2X receptors. The experiments indicate that the opening of the permeation pathway requires similar and substantial movements of the transmembrane helices in both P2X receptors and ASICs, and the method will allow precise optical control of P2X receptors or ASICs in intact tissues.

  20. Optical control of trimeric P2X receptors and acid-sensing ion channels

    PubMed Central

    Browne, Liam E.; Nunes, João P. M.; Sim, Joan A.; Chudasama, Vijay; Bragg, Laricia; Caddick, Stephen; Alan North, R.

    2014-01-01

    P2X receptors are trimeric membrane proteins that function as ion channels gated by extracellular ATP. We have engineered a P2X2 receptor that opens within milliseconds by irradiation at 440 nm, and rapidly closes at 360 nm. This requires bridging receptor subunits via covalent attachment of 4,4'-bis(maleimido)azobenzene to a cysteine residue (P329C) introduced into each second transmembrane domain. The cis–trans isomerization of the azobenzene pushes apart the outer ends of the transmembrane helices and opens the channel in a light-dependent manner. Light-activated channels exhibited similar unitary currents, rectification, calcium permeability, and dye uptake as P2X2 receptors activated by ATP. P2X3 receptors with an equivalent mutation (P320C) were also light sensitive after chemical modification. They showed typical rapid desensitization, and they could coassemble with native P2X2 subunits in pheochromocytoma cells to form light-activated heteromeric P2X2/3 receptors. A similar approach was used to open and close human acid-sensing ion channels (ASICs), which are also trimers but are unrelated in sequence to P2X receptors. The experiments indicate that the opening of the permeation pathway requires similar and substantial movements of the transmembrane helices in both P2X receptors and ASICs, and the method will allow precise optical control of P2X receptors or ASICs in intact tissues. PMID:24367083

  1. Free fatty acids-sensing G protein-coupled receptors in drug targeting and therapeutics.

    PubMed

    Yonezawa, Tomo; Kurata, Riho; Yoshida, Kaori; Murayama, Masanori A; Cui, Xiaofeng; Hasegawa, Akihiko

    2013-01-01

    G protein-coupled receptor (GPCR) (also known as seven-transmembrane domain receptor) superfamily represents the largest protein family in the human genome. These receptors respond to various physiological ligands such as photons, odors, pheromones, hormones, ions, and small molecules including amines, amino acids to large peptides and steroids. Thus, GPCRs are involved in many diseases and the target of around half of all conventional drugs. The physiological roles of free fatty acids (FFAs), in particular, long-chain FFAs, are important for the development of many metabolic disease including obesity, diabetes, and atherosclerosis. In the past half decade, deorphanization of several GPCRs has revealed that GPR40, GPR41, GPR43, GPR84 and GPR120 sense concentration of extracellular FFAs with various carbon chain lengths. GPR40 and GPR120 are activated by medium- and long-chain FFAs. GPR84 is activated by medium- chain, but not long-chain, FFAs. GPR41 and GPR43 are activated by short-chain FFAs. GPR40 is highly expressed in pancreatic beta cells and plays a crucial role in FFAs-induced insulin secretion. GPR120 is mainly expressed in enteroendocrine cells and plays an important role for FFAs-induced glucagon-like peptide-1. GPR43 is abundant in leukocytes and adipose tissue, whilst GPR41 is highly expressed in adipose tissue, the pancreas and leukocytes. GPR84 is expressed in leukocytes and monocyte/macrophage. This review aims to shed light on the physiological roles and development of drugs targeting these receptors.

  2. A single amino acid residue controls Ca2+ signaling by an octopamine receptor from Drosophila melanogaster

    PubMed Central

    Hoff, Max; Balfanz, Sabine; Ehling, Petra; Gensch, Thomas; Baumann, Arnd

    2011-01-01

    Rhythmic activity of cells and cellular networks plays an important role in physiology. In the nervous system oscillations of electrical activity and/or second messenger concentrations are important to synchronize neuronal activity. At the molecular level, rhythmic activity can be initiated by different routes. We have recently shown that an octopamine-activated G-protein-coupled receptor (GPCR; DmOctα1Rb, CG3856) from Drosophila initiates Ca2+ oscillations. Here, we have unraveled the molecular basis of cellular Ca2+ signaling controlled by the DmOctα1Rb receptor using a combination of pharmacological intervention, site-directed mutagenesis, and functional cellular Ca2+ imaging on heterologously expressed receptors. Phosphorylation of a single amino acid residue in the third intracellular loop of the GPCR by PKC is necessary and sufficient to desensitize the receptor. From its desensitized state, DmOctα1Rb is resensitized by dephosphorylation, and a new Ca2+ signal occurs on octopamine stimulation. Our findings show that transient changes of the receptor's surface profile have a strong effect on its physiological signaling properties. We expect that the detailed knowledge of DmOctα1Rb-dependent signal transduction fosters the identification of specific drugs that can be used for GPCR-mediated pest control, since octopamine serves important physiological and behavioral functions in arthropods.—Hoff M., Balfanz, S., Ehling, P., Gensch, T., Baumann, A. A single amino acid residue controls Ca2+ signaling by an octopamine receptor from Drosophila melanogaster. PMID:21478261

  3. Glucocorticoid-dependent induction of interleukin-6 receptor expression in human hepatocytes facilitates interleukin-6 stimulation of amino acid transport.

    PubMed

    Fischer, C P; Bode, B P; Takahashi, K; Tanabe, K K; Souba, W W

    1996-05-01

    The authors studied the effects of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) on glutamine and alanine transport in isolated human hepatocytes. They also evaluated the role of dexamethasone in modulating this response and its effects on the expression of the plasma membrane high-affinity IL-6 receptor. Animal studies indicate that cytokines are important mediators of the increased hepatic amino acid uptake that occurs during cancer and sepsis, but studies in human tissues are lacking. The control of transport by cytokines and cytokine receptor expression in the liver may provide a mechanism by which hepatocytes can modulate amino acid availability during catabolic disease states. Human hepatocytes were isolated from wedge biopsy specimens and plated in 24-well trays. Interleukin-6 and TNF-alpha, in combination with the synthetic glucocorticoid dexamethasone, were added to hepatocytes in culture, and the transport of radiolabeled glutamine and alanine was measured. Fluorescent-activated cell sorter (FACS) analysis was used to study the effects of dexamethasone on IL-6 receptor number in the well-differentiated human hepatoma HepG2. Both IL-6 and TNF-alpha exerted a small stimulatory effect on alanine and glutamine transport. Dexamethasone alone did not alter transport rates, but pretreatment of cells augmented the effects of both cytokines on carrier-mediated amino acid uptake. Dexamethasone pretreatment and a combination of IL-6 and TNF-alpha resulted in a greater than twofold increase in transport activity. Fluorescent-activated cell sorter analysis demonstrated that dexamethasone induced a threefold increase in the expression of high-affinity IL-6 receptors. Interleukin-6 and TNF-alpha work coordinately with glucocorticoids to stimulate amino acid uptake in human hepatocytes. Dexamethasone exerts a permissive effect on cytokine-mediated increases in transport by increasing IL-6 receptor expression on the cell surface. It is likely that this

  4. The short chain fatty acid receptor, FFA2, contributes to gestational glucose homeostasis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fuller, Miles; Priyadarshini, Medha; Gibbons, Sean M.

    The structure of the human gastrointestinal microbiota can change during pregnancy, which may influence gestational metabolism; however, a mechanism of action remains unclear. Here we observed that in wild-type (WT) mice the relative abundance of Actinobacteria and Bacteroidetes increased during pregnancy. Along with these changes, short-chain fatty acids (SCFAs), which are mainly produced through gut microbiota fermentation, significantly changed in both the cecum and peripheral blood throughout gestation in these mice. SCFAs are recognized by G protein-coupled receptors (GPCRs) such as free fatty acid receptor-2 (FFA2), and we have previously demonstrated that the fatty acid receptor-2 gene ( Ffar2) expressionmore » is higher in pancreatic islets during pregnancy. Using female Ffar2-/- mice, we explored the physiological relevance of signaling through this GPCR and found that Ffar2-deficient female mice developed fasting hyperglycemia and impaired glucose tolerance in the setting of impaired insulin secretion compared with WT mice during, but not before, pregnancy. Insulin tolerance tests were similar in Ffar2-/- and WT mice before and during pregnancy. Next, we examined the role of FFA2 in gestational β-cell mass, observing that Ffar2-/- mice had diminished gestational expansion of β-cells during pregnancy. Interestingly, mouse genotype had no significant impact on the composition of the gut microbiome, but did affect the observed SCFA profiles, suggesting a functional difference in the microbiota. Altogether, these results suggest a potential link between increased Ffar2 expression in islets and the alteration of circulating SCFA levels, possibly explaining how changes in the gut microbiome contribute to gestational glucose homeostasis.« less

  5. The short chain fatty acid receptor, FFA2, contributes to gestational glucose homeostasis

    DOE PAGES

    Fuller, Miles; Priyadarshini, Medha; Gibbons, Sean M.; ...

    2015-09-22

    The structure of the human gastrointestinal microbiota can change during pregnancy, which may influence gestational metabolism; however, a mechanism of action remains unclear. Here we observed that in wild-type (WT) mice the relative abundance of Actinobacteria and Bacteroidetes increased during pregnancy. Along with these changes, short-chain fatty acids (SCFAs), which are mainly produced through gut microbiota fermentation, significantly changed in both the cecum and peripheral blood throughout gestation in these mice. SCFAs are recognized by G protein-coupled receptors (GPCRs) such as free fatty acid receptor-2 (FFA2), and we have previously demonstrated that the fatty acid receptor-2 gene ( Ffar2) expressionmore » is higher in pancreatic islets during pregnancy. Using female Ffar2-/- mice, we explored the physiological relevance of signaling through this GPCR and found that Ffar2-deficient female mice developed fasting hyperglycemia and impaired glucose tolerance in the setting of impaired insulin secretion compared with WT mice during, but not before, pregnancy. Insulin tolerance tests were similar in Ffar2-/- and WT mice before and during pregnancy. Next, we examined the role of FFA2 in gestational β-cell mass, observing that Ffar2-/- mice had diminished gestational expansion of β-cells during pregnancy. Interestingly, mouse genotype had no significant impact on the composition of the gut microbiome, but did affect the observed SCFA profiles, suggesting a functional difference in the microbiota. Altogether, these results suggest a potential link between increased Ffar2 expression in islets and the alteration of circulating SCFA levels, possibly explaining how changes in the gut microbiome contribute to gestational glucose homeostasis.« less

  6. Short-chain free fatty acid receptors FFA2/GPR43 and FFA3/GPR41 as new potential therapeutic targets

    PubMed Central

    Ulven, Trond

    2012-01-01

    The deorphanization of the free fatty acid (FFA) receptors FFA1 (GPR40), FFA2 (GPR43), FFA3 (GPR41), GPR84, and GPR120 has made clear that the body is capable of recognizing and responding directly to nonesterified fatty acid of virtually any chain length. Colonic fermentation of dietary fiber produces high concentrations of the short-chain fatty acids (SCFAs) acetate, propionate and butyrate, a process which is important to health. The phylogenetically related 7-transmembrane (7TM) receptors free fatty acid receptor 2 (FFA2) and FFA3 are activated by these SCFAs, and several lines of evidence indicate that FFA2 and FFA3 mediate beneficial effects associated with a fiber-rich diet, and that they may be of interest as targets for treatment of inflammatory and metabolic diseases. FFA2 is highly expressed on immune cells, in particular neutrophils, and several studies suggest that the receptor plays a role in diseases involving a dysfunctional neutrophil response, such as inflammatory bowel disease (IBD). Both FFA2 and FFA3 have been implicated in metabolic diseases such as type 2 diabetes and in regulation of appetite. More research is however required to clarify the potential of the receptors as drug targets and establish if activation or inhibition would be the preferred mode of action. The availability of potent and selective receptor modulators is a prerequisite for these studies. The few modulators of FFA2 or FFA3 that have been published hitherto in the peer-reviewed literature in general have properties that make them less than ideal as such tools, but published patent applications indicate that better tool compounds might soon become available which should enable studies critical to validate the receptors as new drug targets. PMID:23060857

  7. Short-chain free fatty acid receptors FFA2/GPR43 and FFA3/GPR41 as new potential therapeutic targets.

    PubMed

    Ulven, Trond

    2012-01-01

    The deorphanization of the free fatty acid (FFA) receptors FFA1 (GPR40), FFA2 (GPR43), FFA3 (GPR41), GPR84, and GPR120 has made clear that the body is capable of recognizing and responding directly to nonesterified fatty acid of virtually any chain length. Colonic fermentation of dietary fiber produces high concentrations of the short-chain fatty acids (SCFAs) acetate, propionate and butyrate, a process which is important to health. The phylogenetically related 7-transmembrane (7TM) receptors free fatty acid receptor 2 (FFA2) and FFA3 are activated by these SCFAs, and several lines of evidence indicate that FFA2 and FFA3 mediate beneficial effects associated with a fiber-rich diet, and that they may be of interest as targets for treatment of inflammatory and metabolic diseases. FFA2 is highly expressed on immune cells, in particular neutrophils, and several studies suggest that the receptor plays a role in diseases involving a dysfunctional neutrophil response, such as inflammatory bowel disease (IBD). Both FFA2 and FFA3 have been implicated in metabolic diseases such as type 2 diabetes and in regulation of appetite. More research is however required to clarify the potential of the receptors as drug targets and establish if activation or inhibition would be the preferred mode of action. The availability of potent and selective receptor modulators is a prerequisite for these studies. The few modulators of FFA2 or FFA3 that have been published hitherto in the peer-reviewed literature in general have properties that make them less than ideal as such tools, but published patent applications indicate that better tool compounds might soon become available which should enable studies critical to validate the receptors as new drug targets.

  8. MEK blockade converts AML differentiating response to retinoids into extensive apoptosis.

    PubMed

    Milella, Michele; Konopleva, Marina; Precupanu, Cristina M; Tabe, Yoko; Ricciardi, Maria Rosaria; Gregorj, Chiara; Collins, Steven J; Carter, Bing Z; D'Angelo, Carmen; Petrucci, Maria Teresa; Foà, Robin; Cognetti, Francesco; Tafuri, Agostino; Andreeff, Michael

    2007-03-01

    The aberrant function of transcription factors and/or kinase-based signaling pathways that regulate the ability of hematopoietic cells to proliferate, differentiate, and escape apoptosis accounts for the leukemic transformation of myeloid progenitors. Here, we demonstrate that simultaneous retinoid receptor ligation and blockade of the MEK/ERK signaling module, using the small-molecule inhibitor CI-1040, result in a strikingly synergistic induction of apoptosis in both acute myeloid leukemia (AML) and acute promyelocytic leukemia (APL) cells with constitutive ERK activation. This proapoptotic synergism requires functional RAR and RXR retinoid receptors, as demonstrated using RAR- and RXR-selective ligands and RAR-defective cells. In the presence of MEK inhibitors, however, retinoid-induced chromatin remodeling, target-gene transcription, and granulocytic differentiation are strikingly inhibited and apoptosis induction becomes independent of death-inducing ligand/receptor pairs; this suggests that apoptosis induction by combined retinoids and MEK inhibitors is entirely distinct from the classical "postmaturation" apoptosis induced by retinoids alone. Finally, we identify disruption of Bcl-2-dependent mitochondrial homeostasis as a possible point of convergence for the proapoptotic synergism observed with retinoids and MEK inhibitors. Taken together, these results indicate that combined retinoid treatment and MEK blockade exert powerful antileukemic effects and could be developed into a novel therapeutic strategy for both AML and APL.

  9. Cholestenoic acids regulate motor neuron survival via liver X receptors

    PubMed Central

    Theofilopoulos, Spyridon; Griffiths, William J.; Crick, Peter J.; Yang, Shanzheng; Meljon, Anna; Ogundare, Michael; Kitambi, Satish Srinivas; Lockhart, Andrew; Tuschl, Karin; Clayton, Peter T.; Morris, Andrew A.; Martinez, Adelaida; Reddy, M. Ashwin; Martinuzzi, Andrea; Bassi, Maria T.; Honda, Akira; Mizuochi, Tatsuki; Kimura, Akihiko; Nittono, Hiroshi; De Michele, Giuseppe; Carbone, Rosa; Criscuolo, Chiara; Yau, Joyce L.; Seckl, Jonathan R.; Schüle, Rebecca; Schöls, Ludger; Sailer, Andreas W.; Kuhle, Jens; Fraidakis, Matthew J.; Gustafsson, Jan-Åke; Steffensen, Knut R.; Björkhem, Ingemar; Ernfors, Patrik; Sjövall, Jan; Arenas, Ernest; Wang, Yuqin

    2014-01-01

    Cholestenoic acids are formed as intermediates in metabolism of cholesterol to bile acids, and the biosynthetic enzymes that generate cholestenoic acids are expressed in the mammalian CNS. Here, we evaluated the cholestenoic acid profile of mammalian cerebrospinal fluid (CSF) and determined that specific cholestenoic acids activate the liver X receptors (LXRs), enhance islet-1 expression in zebrafish, and increase the number of oculomotor neurons in the developing mouse in vitro and in vivo. While 3β,7α-dihydroxycholest-5-en-26-oic acid (3β,7α-diHCA) promoted motor neuron survival in an LXR-dependent manner, 3β-hydroxy-7-oxocholest-5-en-26-oic acid (3βH,7O-CA) promoted maturation of precursors into islet-1+ cells. Unlike 3β,7α-diHCA and 3βH,7O-CA, 3β-hydroxycholest-5-en-26-oic acid (3β-HCA) caused motor neuron cell loss in mice. Mutations in CYP7B1 or CYP27A1, which encode enzymes involved in cholestenoic acid metabolism, result in different neurological diseases, hereditary spastic paresis type 5 (SPG5) and cerebrotendinous xanthomatosis (CTX), respectively. SPG5 is characterized by spastic paresis, and similar symptoms may occur in CTX. Analysis of CSF and plasma from patients with SPG5 revealed an excess of the toxic LXR ligand, 3β-HCA, while patients with CTX and SPG5 exhibited low levels of the survival-promoting LXR ligand 3β,7α-diHCA. Moreover, 3β,7α-diHCA prevented the loss of motor neurons induced by 3β-HCA in the developing mouse midbrain in vivo.Our results indicate that specific cholestenoic acids selectively work on motor neurons, via LXR, to regulate the balance between survival and death. PMID:25271621

  10. Specificity of the Antibody Receptor Site to D-Lysergamide: Model of a Physiological Receptor for Lysergic Acid Diethylamide

    PubMed Central

    Vunakis, Helen Van; Farrow, John T.; Gjika, Hilda B.; Levine, Lawrence

    1971-01-01

    Antibodies to D-lysergic acid have been produced in rabbits and guinea pigs and a radioimmunoassay for the hapten was developed. The specificity of this lysergamide-antilysergamide reaction was determined by competitive binding with unlabeled lysergic acid diethylamide (LSD), psychotomimetic drugs, neurotransmitters, and other compounds with diverse structures. LSD and several related ergot alkaloids were potent competitors, three to seven times more potent than lysergic acid itself. The N,N-dimethyl derivatives of several compounds, including tryptamine, 5-hydroxytryptamine, 4-hydroxytryptamine, 5-methoxytryptamine, tyramine, and mescaline, were only about ten times less effective than lysergic acid, even though these compounds lack some of the ring systems of lysergic acid. The pattern of inhibition by related compounds with various substituents suggests that the antibody receptor site recognizes structural features resembling the LSD molecule. In particular, the aromatic nucleus and the dimethylated ethylamine side chain in phenylethylamine and tryptamine derivatives may assume in solution a conformation resembling ring A and the methylated nitrogen in ring C of LSD. Among the tryptamine derivatives, a large percentage of the most potent competitors are also psychotomimetic compounds. PMID:5283939

  11. Functional screening for G protein-coupled receptor targets of 14,15-epoxyeicosatrienoic acid.

    PubMed

    Liu, Xuehong; Qian, Zu-Yuan; Xie, Fuchun; Fan, Wei; Nelson, Jonathan W; Xiao, Xiangshu; Kaul, Sanjiv; Barnes, Anthony P; Alkayed, Nabil J

    2017-09-01

    Epoxyeicosatrienoic acids (EETs) are potent vasodilators that play important roles in cardiovascular physiology and disease, yet the molecular mechanisms underlying the biological actions of EETs are not fully understood. Multiple lines of evidence suggest that the actions of EETs are in part mediated via G protein-coupled receptor (GPCR) signaling, but the identity of such a receptor has remained elusive. We sought to identify 14,15-EET-responsive GPCRs. A set of 105 clones were expressed in Xenopus oocyte and screened for their ability to activate cAMP-dependent chloride current. Several receptors responded to micromolar concentrations of 14,15-EET, with the top five being prostaglandin receptor subtypes (PTGER 2 , PTGER 4 , PTGFR, PTGDR, PTGER 3 IV). Overall, our results indicate that multiple low-affinity 14,15-EET GPCRs are capable of increasing cAMP levels following 14,15-EET stimulation, highlighting the potential for cross-talk between prostanoid and other ecosanoid GPCRs. Our data also indicate that none of the 105 GPCRs screened met our criteria for a high-affinity receptor for 14,15-EET. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Retinoic acid receptor-related orphan receptor α-induced activation of adenosine monophosphate-activated protein kinase results in attenuation of hepatic steatosis.

    PubMed

    Kim, Eun-Jin; Yoon, Young-Sil; Hong, Suckchang; Son, Ho-Young; Na, Tae-Young; Lee, Min-Ho; Kang, Hyun-Jin; Park, Jinyoung; Cho, Won-Jea; Kim, Sang-Gun; Koo, Seung-Hoi; Park, Hyeung-geun; Lee, Mi-Ock

    2012-05-01

    There is increasing evidence that the retinoic acid receptor-related orphan receptor α (RORα) plays an important role in the regulation of metabolic pathways, particularly of fatty acid and cholesterol metabolism; however, the role of RORα in the regulation of hepatic lipogenesis has not been studied. Here, we report that RORα attenuates hepatic steatosis, probably via activation of the adenosine monophosphate (AMP)-activated protein kinase (AMPK) and repression of the liver X receptor α (LXRα). First, RORα and its activator, cholesterol sulfate (CS), induced phosphorylation of AMPK, which was accompanied by the activation of serine-threonine kinase liver kinase B1 (LKB1). Second, the activation of RORα, either by transient transfection or CS treatment, decreased the TO901317-induced transcriptional expression of LXRα and its downstream target genes, such as the sterol regulatory element binding protein-1 (SREBP-1) and fatty acid synthase. RORα interacted physically with LXRα and inhibited the LXRα response element in the promoter of LXRα, indicating that RORα interrupts the autoregulatory activation loop of LXRα. Third, infection with adenovirus encoding RORα suppressed the lipid accumulation that had been induced by a free-fatty-acid mixture in cultured cells. Furthermore, we observed that the level of expression of the RORα protein was decreased in the liver of mice that were fed a high-fat diet. Restoration of RORα via tail-vein injection of adenovirus (Ad)-RORα decreased the high-fat-diet-induced hepatic steatosis. Finally, we synthesized thiourea derivatives that activated RORα, thereby inducing activation of AMPK and repression of LXRα. These compounds decreased hepatic triglyceride levels and lipid droplets in the high-fat-diet-fed mice. We found that RORα induced activation of AMPK and inhibition of the lipogenic function of LXRα, which may be key phenomena that provide the beneficial effects of RORα against hepatic steatosis

  13. Phosphatase inhibitors remove the run-down of γ-aminobutyric acid type A receptors in the human epileptic brain

    PubMed Central

    Palma, E.; Ragozzino, D. A.; Di Angelantonio, S.; Spinelli, G.; Trettel, F.; Martinez-Torres, A.; Torchia, G.; Arcella, A.; Di Gennaro, G.; Quarato, P. P.; Esposito, V.; Cantore, G.; Miledi, R.; Eusebi, F.

    2004-01-01

    The properties of γ-aminobutyric acid (GABA) type A receptors (GABAA receptors) microtransplanted from the human epileptic brain to the plasma membrane of Xenopus oocytes were compared with those recorded directly from neurons, or glial cells, in human brains slices. Cell membranes isolated from brain specimens, surgically obtained from six patients afflicted with drug-resistant temporal lobe epilepsy (TLE) were injected into frog oocytes. Within a few hours, these oocytes acquired GABAA receptors that generated GABA currents with an unusual run-down, which was inhibited by orthovanadate and okadaic acid. In contrast, receptors derived from membranes of a nonepileptic hippocampal uncus, membranes from mouse brain, or recombinant rat α1β2γ2-GABA receptors exhibited a much less pronounced GABA-current run-down. Moreover, the GABAA receptors of pyramidal neurons in temporal neocortex slices from the same six epileptic patients exhibited a stronger run-down than the receptors of rat pyramidal neurons. Interestingly, the GABAA receptors of neighboring glial cells remained substantially stable after repetitive activation. Therefore, the excessive GABA-current run-down observed in the membrane-injected oocytes recapitulates essentially what occurs in neurons, rather than in glial cells. Quantitative RT-PCR analyses from the same TLE neocortex specimens revealed that GABAA-receptor β1, β2, β3, and γ2 subunit mRNAs were significantly overexpressed (8- to 33-fold) compared with control autopsy tissues. Our results suggest that an abnormal GABA-receptor subunit transcription in the TLE brain leads to the expression of run-down-enhanced GABAA receptors. Blockage of phosphatases stabilizes the TLE GABAA receptors and strengthens GABAergic inhibition. It may be that this process can be targeted to develop new treatments for intractable epilepsy. PMID:15218107

  14. Okadaic acid induces epileptic seizures and hyperphosphorylation of the NR2B subunit of the NMDA receptor in rat hippocampus in vivo.

    PubMed

    Arias, Clorinda; Montiel, Teresa; Peña, Fernando; Ferrera, Patricia; Tapia, Ricardo

    2002-09-01

    Overactivation of N-methyl-D-aspartate (NMDA) glutamate receptors is closely related to epilepsy and excitotoxicity, and the phosphorylation of these receptors may facilitate glutamate-mediated synaptic transmission. Here we show that in awake rats the microinjection into the hippocampus of okadaic acid, a potent inhibitor of protein phosphatases 1 and 2A, induces in about 20 min intense electroencephalographic and behavioral limbic-type seizures, which are suppressed by the systemic administration of the NMDA receptor antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]cyclohepten-5,10-imine hydrogen maleate and by the intrahippocampal administration of 1-(5-isoquinolinesulfonyl)-2-methylpiperazine, an inhibitor of protein kinases. Two hours after okadaic acid, when the EEG seizures were intense, an increased serine phosphorylation of some hippocampal proteins, including an enhancement of the serine phosphorylation of the NMDA receptor subunit NR2B, was detected by immunoblotting. Twenty-four hours after okadaic acid a marked destruction of hippocampal CA1 region was observed, which was not prevented by the receptor antagonists. These findings suggest that hyperphosphorylation of glutamate receptors in vivo may result in an increased sensitivity to the endogenous transmitter and therefore induce neuronal hyperexcitability and epilepsy.

  15. A novel polymorphism in the oxytocin receptor encoding gene (OXTR) affects milk fatty acid composition in Italian Mediterranean river buffalo.

    PubMed

    Cosenza, Gianfranco; Macciotta, Nicolò P P; Nudda, Anna; Coletta, Angelo; Ramunno, Luigi; Pauciullo, Alfredo

    2017-05-01

    The oxytocin receptor, also known as OXTR, is a protein which functions as receptor for the hormone and neurotransmitter oxytocin and the complex oxytocin-oxytocin receptor plays an important role in the uterus during calving. A characterisation of the river buffalo OXTR gene, amino acid sequences and phylogenetic analysis is presented. The DNA regions of the OXTR gene spanning exons 1, 2 and 3 of ten Mediterranean river buffalo DNA samples were analysed and 7 single nucleotide polymorphisms were found. We focused on the g.129C > T SNP detected in exon 3 and responsible for the amino acid replacement CGCArg > TGCCys in position 353. The relative frequency of T allele was of 0·257. An association study between this detected polymorphism and milk fatty acids composition in Italian Mediterranean river buffalo was carried out. The fatty acid composition traits, fatty acid classes and fat percentage of 306 individual milk samples were determined. Associations between OXTR g.129C > T genotype and milk fatty acids composition were tested using a mixed linear model. The OXTR CC genotype was found significantly associated with higher contents of odd branched-chain fatty acids (OBCFA) (P < 0·0006), polyunsaturated FA (PUFA n 3 and n 6) (P < 0·0032 and P < 0·0006, respectively), stearic acid (C18) (P < 0·02) and lower level of palmitic acid (C16) (P < 0·02). The results of this study suggest that the OXTR CC animals might be useful in selection toward the improvement of milk fatty acid composition.

  16. Retinoic Acid Isomers Facilitate Apolipoprotein E Production and Lipidation in Astrocytes through the Retinoid X Receptor/Retinoic Acid Receptor Pathway*

    PubMed Central

    Zhao, Jing; Fu, Yuan; Liu, Chia-Chen; Shinohara, Mitsuru; Nielsen, Henrietta M.; Dong, Qiang; Kanekiyo, Takahisa; Bu, Guojun

    2014-01-01

    Apolipoprotein E (apoE) is the major cholesterol transport protein in the brain. Among the three human APOE alleles (APOE2, APOE3, and APOE4), APOE4 is the strongest genetic risk factor for late-onset Alzheimer disease (AD). The accumulation of amyloid-β (Aβ) is a central event in AD pathogenesis. Increasing evidence demonstrates that apoE isoforms differentially regulate AD-related pathways through both Aβ-dependent and -independent mechanisms; therefore, modulating apoE secretion, lipidation, and function might be an attractive approach for AD therapy. We performed a drug screen for compounds that modulate apoE production in immortalized astrocytes derived from apoE3-targeted replacement mice. Here, we report that retinoic acid (RA) isomers, including all-trans-RA, 9-cis-RA, and 13-cis-RA, significantly increase apoE secretion to ∼4-fold of control through retinoid X receptor (RXR) and RA receptor. These effects on modulating apoE are comparable with the effects recently reported for the RXR agonist bexarotene. Furthermore, all of these compounds increased the expression of the cholesterol transporter ABCA1 and ABCG1 levels and decreased cellular uptake of Aβ in an apoE-dependent manner. Both bexarotene and 9-cis-RA promote the lipidation status of apoE, in which 9-cis-RA promotes a stronger effect and exhibits less cytotoxicity compared with bexarotene. Importantly, we showed that oral administration of bexarotene and 9-cis-RA significantly increases apoE, ABCA1, and ABCG1 levels in mouse brains. Taken together, our results demonstrate that RXR/RA receptor agonists, including several RA isomers, are effective modulators of apoE secretion and lipidation and may be explored as potential drugs for AD therapy. PMID:24599963

  17. Avian and human influenza virus compatible sialic acid receptors in little brown bats.

    PubMed

    Chothe, Shubhada K; Bhushan, Gitanjali; Nissly, Ruth H; Yeh, Yin-Ting; Brown, Justin; Turner, Gregory; Fisher, Jenny; Sewall, Brent J; Reeder, DeeAnn M; Terrones, Mauricio; Jayarao, Bhushan M; Kuchipudi, Suresh V

    2017-04-06

    Influenza A viruses (IAVs) continue to threaten animal and human health globally. Bats are asymptomatic reservoirs for many zoonotic viruses. Recent reports of two novel IAVs in fruit bats and serological evidence of avian influenza virus (AIV) H9 infection in frugivorous bats raise questions about the role of bats in IAV epidemiology. IAVs bind to sialic acid (SA) receptors on host cells, and it is widely believed that hosts expressing both SA α2,3-Gal and SA α2,6-Gal receptors could facilitate genetic reassortment of avian and human IAVs. We found abundant co-expression of both avian (SA α2,3-Gal) and human (SA α2,6-Gal) type SA receptors in little brown bats (LBBs) that were compatible with avian and human IAV binding. This first ever study of IAV receptors in a bat species suggest that LBBs, a widely-distributed bat species in North America, could potentially be co-infected with avian and human IAVs, facilitating the emergence of zoonotic strains.

  18. Leveraging abscisic acid receptors for efficient water use in Arabidopsis

    PubMed Central

    Yang, Zhenyu; Liu, Jinghui; Tischer, Stefanie V.; Christmann, Alexander; Windisch, Wilhelm; Schnyder, Hans; Grill, Erwin

    2016-01-01

    Plant growth requires the influx of atmospheric CO2 through stomatal pores, and this carbon uptake for photosynthesis is inherently associated with a large efflux of water vapor. Under water deficit, plants reduce transpiration and are able to improve carbon for water exchange leading to higher water use efficiency (WUE). Whether increased WUE can be achieved without trade-offs in plant growth is debated. The signals mediating the WUE response under water deficit are not fully elucidated but involve the phytohormone abscisic acid (ABA). ABA is perceived by a family of related receptors known to mediate acclimation responses and to reduce transpiration. We now show that enhanced stimulation of ABA signaling via distinct ABA receptors can result in plants constitutively growing at high WUE in the model species Arabidopsis. WUE was assessed by three independent approaches involving gravimetric analyses, 13C discrimination studies of shoots and derived cellulose fractions, and by gas exchange measurements of whole plants and individual leaves. Plants expressing the ABA receptors RCAR6/PYL12 combined up to 40% increased WUE with high growth rates, i.e., are water productive. Water productivity was associated with maintenance of net carbon assimilation by compensatory increases of leaf CO2 gradients, thereby sustaining biomass acquisition. Leaf surface temperatures and growth potentials of plants growing under well-watered conditions were found to be reliable indicators for water productivity. The study shows that ABA receptors can be explored to generate more plant biomass per water transpired, which is a prime goal for a more sustainable water use in agriculture. PMID:27247417

  19. Electro-olfactogram and multiunit olfactory receptor responses to binary and trinary mixtures of amino acids in the channel catfish, Ictalurus punctatus

    PubMed Central

    1989-01-01

    In vivo electrophysiological recordings from populations of olfactory receptor neurons in the channel catfish, Ictalurus punctatus, clearly showed that responses to binary and trinary mixtures of amino acids were predictable with knowledge obtained from previous cross-adaptation studies of the relative independence of the respective binding sites of the component stimuli. All component stimuli, from which equal aliquots were drawn to form the mixtures, were adjusted in concentration to provide for approximately equal response magnitudes. The magnitude of the response to a mixture whose component amino acids showed significant cross-reactivity was equivalent to the response to any single component used to form that mixture. A mixture whose component amino acids showed minimal cross-adaptation produced a significantly larger relative response than a mixture whose components exhibited considerable cross-reactivity. This larger response approached the sum of the responses to the individual component amino acids tested at the resulting concentrations in the mixture, even though olfactory receptor dose-response functions for amino acids in this species are characterized by extreme sensory compression (i.e., successive concentration increments produce progressively smaller physiological responses). Thus, the present study indicates that the response to sensory stimulation of olfactory receptor sites is more enhanced by the activation of different receptor site types than by stimulus interaction at a single site type. PMID:2703818

  20. Novel protective role of the circadian nuclear receptor retinoic acid-related orphan receptor-α in diabetic cardiomyopathy.

    PubMed

    Zhao, Yichao; Xu, Longwei; Ding, Song; Lin, Nan; Ji, Qingqi; Gao, Lingchen; Su, Yuanyuan; He, Ben; Pu, Jun

    2017-04-01

    Diabetic cardiomyopathy is a major complication that significantly contributes to morbidity and mortality in diabetics with few therapies. Moreover, antidiabetic drugs reported inconsistent or even adverse cardiovascular effects, suggesting that it is important to exploit novel therapeutic targets against diabetic cardiomyopathy. Here, we observed that the nuclear melatonin receptor, the retinoic acid-related orphan receptor-α (RORα), was downregulated in diabetic hearts. By utilizing a mouse line with RORα disruption, we demonstrated that RORα deficiency led to significantly augmented diastolic dysfunction and cardiac remodeling induced by diabetes. Microscopic and molecular analyses further indicated that the detrimental effects of RORα deficiency were associated with aggravated myocardial apoptosis, autophagy dysfunction, and oxidative stress by disrupting antioxidant gene expression. By contrast, restoration of cardiac RORα levels in transgenic mice significantly improved cardiac functional and structural parameters at 8 weeks after diabetes induction. Consistent with genetic manipulation, pharmacological activation of RORα by melatonin and SR1078 (a synthetic agonist) showed beneficial effects against diabetic cardiomyopathy, while the RORα inhibitor SR3335 significantly exacerbated cardiac impairments in diabetic mice. Collectively, these findings suggest that cardiac-targeted manipulation of nuclear melatonin receptor RORα may hold promise for delaying diabetic cardiomyopathy development. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Coordinated gene expression during gilthead sea bream skeletogenesis and its disruption by nutritional hypervitaminosis A

    PubMed Central

    2011-01-01

    Background Vitamin A (VA) has a key role in vertebrate morphogenesis, determining body patterning and growth through the control of cell proliferation and differentiation processes. VA regulates primary molecular pathways of those processes by the binding of its active metabolite (retinoic acid) to two types of specific nuclear receptors: retinoic acid receptors (RARs) and retinoid X receptors (RXRs), which promote transcription of downstream target genes. This process is well known in most of higher vertebrates; however, scarce information is available regarding fishes. Therefore, in order to gain further knowledge of fish larval development and its disruption by nutritional VA imbalance, the relative expression of some RARs and RXRs, as well as several genes involved in morpho- and skeletogenesis such as peroxisome proliferator-activated receptors (PPARA, PPARB and PPARG); retinol-binding protein (RBP); insulin-like growth factors I and II (IGF1 and IGF2, respectively); bone morphogenetic protein 2 (Bmp2); transforming growth factor β-1 (TGFB1); and genes encoding different extracellular matrix (ECM) proteins such as matrix Gla protein (mgp), osteocalcin (bglap), osteopontin (SPP1), secreted protein acidic and rich in cysteine (SPARC) and type I collagen α1 chain (COL1A1) have been studied in gilthead sea bream. Results During gilthead sea bream larval development, specific expression profiles for each gene were tightly regulated during fish morphogenesis and correlated with specific morphogenetic events and tissue development. Dietary hypervitaminosis A during early larval development disrupted the normal gene expression profile for genes involved in RA signalling (RARA), VA homeostasis (RBP) and several genes encoding ECM proteins that are linked to skeletogenesis, such as bglap and mgp. Conclusions Present data reflects the specific gene expression patterns of several genes involved in larval fish RA signalling and skeletogenesis; and how specific gene

  2. Activated AMPK inhibits PPAR-{alpha} and PPAR-{gamma} transcriptional activity in hepatoma cells.

    PubMed

    Sozio, Margaret S; Lu, Changyue; Zeng, Yan; Liangpunsakul, Suthat; Crabb, David W

    2011-10-01

    AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor-α (PPAR-α) are critical regulators of short-term and long-term fatty acid oxidation, respectively. We examined whether the activities of these molecules were coordinately regulated. H4IIEC3 cells were transfected with PPAR-α and PPAR-γ expression plasmids and a peroxisome-proliferator-response element (PPRE) luciferase reporter plasmid. The cells were treated with PPAR agonists (WY-14,643 and rosiglitazone), AMPK activators 5-aminoimidazole-4-carboxamide riboside (AICAR) and metformin, and the AMPK inhibitor compound C. Both AICAR and metformin decreased basal and WY-14,643-stimulated PPAR-α activity; compound C increased agonist-stimulated reporter activity and partially reversed the effect of the AMPK activators. Similar effects on PPAR-γ were seen, with both AICAR and metformin inhibiting PPRE reporter activity. Compound C increased basal PPAR-γ activity and rosiglitazone-stimulated activity. In contrast, retinoic acid receptor-α (RAR-α), another nuclear receptor that dimerizes with retinoid X receptor (RXR), was largely unaffected by the AMPK activators. Compound C modestly increased AM580 (an RAR agonist)-stimulated activity. The AMPK activators did not affect PPAR-α binding to DNA, and there was no consistent correlation between effects of the AMPK activators and inhibitor on PPAR and the nuclear localization of AMPK-α subunits. Expression of either a constitutively active or dominant negative AMPK-α inhibited basal and WY-14,643-stimulated PPAR-α activity and basal and rosiglitazone-stimulated PPAR-γ activity. We concluded that the AMPK activators AICAR and metformin inhibited transcriptional activities of PPAR-α and PPAR-γ, whereas inhibition of AMPK with compound C activated both PPARs. The effects of AMPK do not appear to be mediated through effects on RXR or on PPAR/RXR binding to DNA. These effects are independent of kinase activity and instead appear to

  3. Coordinated gene expression during gilthead sea bream skeletogenesis and its disruption by nutritional hypervitaminosis A.

    PubMed

    Fernández, Ignacio; Darias, Maria; Andree, Karl B; Mazurais, David; Zambonino-Infante, Jose Luís; Gisbert, Enric

    2011-02-09

    Vitamin A (VA) has a key role in vertebrate morphogenesis, determining body patterning and growth through the control of cell proliferation and differentiation processes. VA regulates primary molecular pathways of those processes by the binding of its active metabolite (retinoic acid) to two types of specific nuclear receptors: retinoic acid receptors (RARs) and retinoid X receptors (RXRs), which promote transcription of downstream target genes. This process is well known in most of higher vertebrates; however, scarce information is available regarding fishes. Therefore, in order to gain further knowledge of fish larval development and its disruption by nutritional VA imbalance, the relative expression of some RARs and RXRs, as well as several genes involved in morpho- and skeletogenesis such as peroxisome proliferator-activated receptors (PPARA, PPARB and PPARG); retinol-binding protein (RBP); insulin-like growth factors I and II (IGF1 and IGF2, respectively); bone morphogenetic protein 2 (Bmp2); transforming growth factor β-1 (TGFB1); and genes encoding different extracellular matrix (ECM) proteins such as matrix Gla protein (mgp), osteocalcin (bglap), osteopontin (SPP1), secreted protein acidic and rich in cysteine (SPARC) and type I collagen α1 chain (COL1A1) have been studied in gilthead sea bream. During gilthead sea bream larval development, specific expression profiles for each gene were tightly regulated during fish morphogenesis and correlated with specific morphogenetic events and tissue development. Dietary hypervitaminosis A during early larval development disrupted the normal gene expression profile for genes involved in RA signalling (RARA), VA homeostasis (RBP) and several genes encoding ECM proteins that are linked to skeletogenesis, such as bglap and mgp. Present data reflects the specific gene expression patterns of several genes involved in larval fish RA signalling and skeletogenesis; and how specific gene disruption induced by a nutritional

  4. Bile acids and their oxo derivatives: Potential inhibitors of carbonic anhydrase I and II, androgen receptor antagonists and CYP3A4 substrates.

    PubMed

    Trifunović, Jovana; Borčić, Vladan; Mikov, Momir

    2017-05-01

    Some biological properties of bile acids and their oxo derivatives have not been sufficiently investigated, although the interest in bile acids as signaling molecules is rising. The aim of this work was to evaluate physico-chemical parametar b (slope) that represents the lipophilicity of the examined molecules and to investigate interactions of bile acids with carbonic anhydrase I, II, androgen receptor and CYP450s. Thirteen candidates were investigated using normal-phase thin-layer chromatography in two solvent systems. Retention parameters were used in further quantitative structure-activity relationship analysis and docking studies to predict interactions and binding affinities of examined molecules with enzymes and receptors. Prediction of activity on androgen receptor showed that compounds 3α-hydroxy-12-oxo-5β-cholanoic and 3α-hydroxy-7-oxo-5β-cholanoic acid have stronger antiandrogen activity than natural bile acids. The inhibitory potential for carbonic anhydrase I and II was tested and it was concluded that molecules 3α-hydroxy-12-oxo-5β-cholanoic, 3α-hydroxy-7-oxo-5β-cholanoic, 3,7,12-trioxo-5β-cholanoic acid and hyodeoxycholic acid show the best results. Substrate behavior for CYP3A4 was confirmed for all investigated compounds. Oxo derivatives of bile acids show stronger interactions with enzymes and receptors as classical bile acids and lower membranolytic activity compared with them. These significant observations could be valuable in consideration of oxo derivatives as building blocks in medicinal chemistry. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Human Coronavirus HKU1 Spike Protein Uses O-Acetylated Sialic Acid as an Attachment Receptor Determinant and Employs Hemagglutinin-Esterase Protein as a Receptor-Destroying Enzyme.

    PubMed

    Huang, Xingchuan; Dong, Wenjuan; Milewska, Aleksandra; Golda, Anna; Qi, Yonghe; Zhu, Quan K; Marasco, Wayne A; Baric, Ralph S; Sims, Amy C; Pyrc, Krzysztof; Li, Wenhui; Sui, Jianhua

    2015-07-01

    Human coronavirus (hCoV) HKU1 is one of six hCoVs identified to date and the only one with an unidentified cellular receptor. hCoV-HKU1 encodes a hemagglutinin-esterase (HE) protein that is unique to the group a betacoronaviruses (group 2a). The function of HKU1-HE remains largely undetermined. In this study, we examined binding of the S1 domain of hCoV-HKU1 spike to a panel of cells and found that the S1 could specifically bind on the cell surface of a human rhabdomyosarcoma cell line, RD. Pretreatment of RD cells with neuraminidase (NA) and trypsin greatly reduced the binding, suggesting that the binding was mediated by sialic acids on glycoproteins. However, unlike other group 2a CoVs, e.g., hCoV-OC43, for which 9-O-acetylated sialic acid (9-O-Ac-Sia) serves as a receptor determinant, HKU1-S1 bound with neither 9-O-Ac-Sia-containing glycoprotein(s) nor rat and mouse erythrocytes. Nonetheless, the HKU1-HE was similar to OC43-HE, also possessed sialate-O-acetylesterase activity, and acted as a receptor-destroying enzyme (RDE) capable of eliminating the binding of HKU1-S1 to RD cells, whereas the O-acetylesterase-inactive HKU1-HE mutant lost this capacity. Using primary human ciliated airway epithelial (HAE) cell cultures, the only in vitro replication model for hCoV-HKU1 infection, we confirmed that pretreatment of HAE cells with HE but not the enzymatically inactive mutant blocked hCoV-HKU1 infection. These results demonstrate that hCoV-HKU1 exploits O-Ac-Sia as a cellular attachment receptor determinant to initiate the infection of host cells and that its HE protein possesses the corresponding sialate-O-acetylesterase RDE activity. Human coronaviruses (hCoV) are important human respiratory pathogens. Among the six hCoVs identified to date, only hCoV-HKU1 has no defined cellular receptor. It is also unclear whether hemagglutinin-esterase (HE) protein plays a role in viral entry. In this study, we found that, similarly to other members of the group 2a CoVs, sialic

  6. The alpha-fetoprotein third domain receptor binding fragment: in search of scavenger and associated receptor targets.

    PubMed

    Mizejewski, G J

    2015-01-01

    Recent studies have demonstrated that the carboxyterminal third domain of alpha-fetoprotein (AFP-CD) binds with various ligands and receptors. Reports within the last decade have established that AFP-CD contains a large fragment of amino acids that interact with several different receptor types. Using computer software specifically designed to identify protein-to-protein interaction at amino acid sequence docking sites, the computer searches identified several types of scavenger-associated receptors and their amino acid sequence locations on the AFP-CD polypeptide chain. The scavenger receptors (SRs) identified were CD36, CD163, Stabilin, SSC5D, SRB1 and SREC; the SR-associated receptors included the mannose, low-density lipoprotein receptors, the asialoglycoprotein receptor, and the receptor for advanced glycation endproducts (RAGE). Interestingly, some SR interaction sites were localized on the AFP-derived Growth Inhibitory Peptide (GIP) segment at amino acids #480-500. Following the detection studies, a structural subdomain analysis of both the receptor and the AFP-CD revealed the presence of epidermal growth factor (EGF) repeats, extracellular matrix-like protein regions, amino acid-rich motifs and dimerization subdomains. For the first time, it was reported that EGF-like sequence repeats were identified on each of the three domains of AFP. Thereafter, the localization of receptors on specific cell types were reviewed and their functions were discussed.

  7. Inhibition of lysophosphatidic acid receptors 1 and 3 attenuates atherosclerosis development in LDL-receptor deficient mice.

    PubMed

    Kritikou, Eva; van Puijvelde, Gijs H M; van der Heijden, Thomas; van Santbrink, Peter J; Swart, Maarten; Schaftenaar, Frank H; Kröner, Mara J; Kuiper, Johan; Bot, Ilze

    2016-11-24

    Lysophosphatidic acid (LPA) is a natural lysophospholipid present at high concentrations within lipid-rich atherosclerotic plaques. Upon local accumulation in the damaged vessels, LPA can act as a potent activator for various types of immune cells through its specific membrane receptors LPA 1/3. LPA elicits chemotactic, pro-inflammatory and apoptotic effects that lead to atherosclerotic plaque progression. In this study we aimed to inhibit LPA signaling by means of LPA 1/3 antagonism using the small molecule Ki16425. We show that LPA 1/3 inhibition significantly impaired atherosclerosis progression. Treatment with Ki16425 also resulted in reduced CCL2 production and secretion, which led to less monocyte and neutrophil infiltration. Furthermore, we provide evidence that LPA 1/3 blockade enhanced the percentage of non-inflammatory, Ly6C low monocytes and CD4 + CD25 + FoxP3 + T-regulatory cells. Finally, we demonstrate that LPA 1/3 antagonism mildly reduced plasma LDL cholesterol levels. Therefore, pharmacological inhibition of LPA 1/3 receptors may prove a promising approach to diminish atherosclerosis development.

  8. Obeticholic acid, a selective farnesoid X receptor agonist, regulates bile acid homeostasis in sandwich-cultured human hepatocytes.

    PubMed

    Zhang, Yuanyuan; Jackson, Jonathan P; St Claire, Robert L; Freeman, Kimberly; Brouwer, Kenneth R; Edwards, Jeffrey E

    2017-08-01

    Farnesoid X receptor (FXR) is a master regulator of bile acid homeostasis through transcriptional regulation of genes involved in bile acid synthesis and cellular membrane transport. Impairment of bile acid efflux due to cholangiopathies results in chronic cholestasis leading to abnormal elevation of intrahepatic and systemic bile acid levels. Obeticholic acid (OCA) is a potent and selective FXR agonist that is 100-fold more potent than the endogenous ligand chenodeoxycholic acid (CDCA). The effects of OCA on genes involved in bile acid homeostasis were investigated using sandwich-cultured human hepatocytes. Gene expression was determined by measuring mRNA levels. OCA dose-dependently increased fibroblast growth factor-19 (FGF-19) and small heterodimer partner (SHP) which, in turn, suppress mRNA levels of cholesterol 7-alpha-hydroxylase (CYP7A1), the rate-limiting enzyme for de novo synthesis of bile acids. Consistent with CYP7A1 suppression, total bile acid content was decreased by OCA (1 μmol/L) to 42.7 ± 20.5% relative to control. In addition to suppressing de novo bile acids synthesis, OCA significantly increased the mRNA levels of transporters involved in bile acid homeostasis. The bile salt excretory pump (BSEP), a canalicular efflux transporter, increased by 6.4 ± 0.8-fold, and the basolateral efflux heterodimer transporters, organic solute transporter α (OST α ) and OST β increased by 6.4 ± 0.2-fold and 42.9 ± 7.9-fold, respectively. The upregulation of BSEP and OST α and OST β, by OCA reduced the intracellular concentrations of d 8 -TCA, a model bile acid, to 39.6 ± 8.9% relative to control. These data demonstrate that OCA does suppress bile acid synthesis and reduce hepatocellular bile acid levels, supporting the use of OCA to treat bile acid-induced toxicity observed in cholestatic diseases. © 2017 Intercept Pharmaceuticals. Pharmacology Research & Perspectives published by John Wiley & Sons Ltd, British Pharmacological Society and

  9. Gamma-Aminobutyric acid and benzodiazepine receptors in the kindling model of epilepsy: a quantitative radiohistochemical study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shin, C.; Pedersen, H.B.; McNamara, J.O.

    1985-10-01

    Quantitative radiohistochemistry was utilized to study alterations of gamma-aminobutyric acid (GABA) and benzodiazepine receptors in the kindling model of epilepsy. The radioligands used for GABA and benzodiazepine receptors were (TH) muscimol and (TH)flunitrazepam, respectively. GABA receptor binding was increased by 22% in fascia dentata of the hippocampal formation but not in neocortex or substantia nigra of kindled rats. Within fascia dentata, GABA receptor binding was increased to an equivalent extent in stratum granulosum and throughout stratum moleculare; no increase was found in dentate hilus or stratum lacunosummoleculare or stratum radiatum of CA1. The increased binding was present at 24 hrmore » but not at 28 days after the last kindled seizure. The direction, anatomic distribution, and time course of the increased GABA receptor binding were paralleled by increased benzodiazepine receptor binding. The anatomic distribution of the increased GABA receptor binding is consistent with a localization to somata and dendritic trees of dentate granule cells. The authors suggest that increased GABA and benzodiazepine receptor binding may contribute to enhanced inhibition of dentate granule cells demonstrated electrophysiologically in kindled animals.« less

  10. Membrane omega-3 fatty acids modulate the oligomerisation kinetics of adenosine A2A and dopamine D2 receptors

    NASA Astrophysics Data System (ADS)

    Guixà-González, Ramon; Javanainen, Matti; Gómez-Soler, Maricel; Cordobilla, Begoña; Domingo, Joan Carles; Sanz, Ferran; Pastor, Manuel; Ciruela, Francisco; Martinez-Seara, Hector; Selent, Jana

    2016-01-01

    Membrane levels of docosahexaenoic acid (DHA), an essential omega-3 polyunsaturated fatty acid (ω-3 PUFA), are decreased in common neuropsychiatric disorders. DHA modulates key cell membrane properties like fluidity, thereby affecting the behaviour of transmembrane proteins like G protein-coupled receptors (GPCRs). These receptors, which have special relevance for major neuropsychiatric disorders have recently been shown to form dimers or higher order oligomers, and evidence suggests that DHA levels affect GPCR function by modulating oligomerisation. In this study, we assessed the effect of membrane DHA content on the formation of a class of protein complexes with particular relevance for brain disease: adenosine A2A and dopamine D2 receptor oligomers. Using extensive multiscale computer modelling, we find a marked propensity of DHA for interaction with both A2A and D2 receptors, which leads to an increased rate of receptor oligomerisation. Bioluminescence resonance energy transfer (BRET) experiments performed on living cells suggest that this DHA effect on the oligomerisation of A2A and D2 receptors is purely kinetic. This work reveals for the first time that membrane ω-3 PUFAs play a key role in GPCR oligomerisation kinetics, which may have important implications for neuropsychiatric conditions like schizophrenia or Parkinson’s disease.

  11. Olfactory receptor Olfr544 responding to azelaic acid regulates glucagon secretion in α-cells of mouse pancreatic islets.

    PubMed

    Kang, NaNa; Bahk, Young Yil; Lee, NaHye; Jae, YoonGyu; Cho, Yoon Hee; Ku, Cheol Ryong; Byun, Youngjoo; Lee, Eun Jig; Kim, Min-Soo; Koo, JaeHyung

    2015-05-08

    Olfactory receptors (ORs) are extensively expressed in olfactory as well as non-olfactory tissues. Although many OR transcripts are expressed in non-olfactory tissues, only a few studies demonstrate the functional role of ORs. Here, we verified that mouse pancreatic α-cells express potential OR-mediated downstream effectors. Moreover, high levels of mRNA for the olfactory receptors Olfr543, Olfr544, Olfr545, and Olfr1349 were expressed in α-cells as assessed using RNA-sequencing, microarray, and quantitative real-time RT-PCR analyses. Treatment with dicarboxylic acids (azelaic acid and sebacic acid) increased intracellular Ca(2+) mobilization in pancreatic α-cells. The azelaic acid-induced Ca(2+) response as well as glucagon secretion was concentration- and time-dependent manner. Olfr544 was expressed in α-cells, and the EC50 value of azelaic acid to Olfr544 was 19.97 μM, whereas Olfr545 did not respond to azelaic acid. Our findings demonstrate that Olfr544 responds to azelaic acid to regulate glucagon secretion through Ca(2+) mobilization in α-cells of the mouse pancreatic islets, suggesting that Olfr544 may be an important therapeutic target for metabolic diseases. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Molecular size of the gamma-aminobutyric acidA receptor purified from mammalian cerebral cortex.

    PubMed

    Mamalaki, C; Barnard, E A; Stephenson, F A

    1989-01-01

    The hydrodynamic behaviour of both the soluble and purified gamma-aminobutyric acidA (GABAA) receptor of bovine or rat cerebral cortex has been investigated in solution in Triton X-100 or in 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulphonate (CHAPS). In all the hydrodynamic separations made, it was found that the binding activities for GABA, benzodiazepine, and (where detectable) t-butylbicyclophosphorothionate comigrated. Conditions were established for gel exclusion chromatography and for sucrose density gradient velocity sedimentation that maintain the GABAA receptor in a nonaggregated form. Using these conditions, the molecular weight of the bovine GABAA receptor in the above-mentioned detergents was calculated using the H2O/2H2O method. A value of Mr 230,000-240,000 was calculated for the bovine pure GABAA receptor purified in sodium deoxycholate/Triton X-100 media. A value of Mr 284,000-290,000 was calculated for the nonaggregated bovine or rat cortex receptor in CHAPS, but the Stokes radius is smaller in the latter than in the former medium and the detergent binding in CHAPS is underestimated. Thus the deduced Mr, 240,000, is the best estimate by this method.

  13. Binding effect of fluorescence labeled glycyrrhetinic acid with GA receptors in hepatocellular carcinoma cells.

    PubMed

    Sun, Yu-Qi; Dai, Chun-Mei; Zheng, Yan; Shi, Shu-Dan; Hu, Hai-Yang; Chen, Da-Wei

    2017-11-01

    Glycyrrhetinic acid (GA) is a natural active component from licorice, which is broadly used in traditional Chinese medicine. Lots of glycyrrhetinic acid receptors (GA-R) are proved to locate on the surface of liver cells. Many reports about the hepatocellular carcinoma (HCC) treatment were dependent on GA modified carriers. However, the reality of GA-R in HCC cells was not clear. In this paper, 18β-glycyrrhetinic acid (18β-GA) was labeled with fluorescence (FITC) by chemical synthesis. Together with the binding effect of fluorescence labeled glycyrrhetinic acid (FITC-GA), the competitive action of 18β-GA with GA-R was investigated in HCC cells. The results showed that in HepG2 cells, 18β-GA and FITC-GA presented similar cytotoxicity. The specific binding saturation of GA showed the dissociation constant (K d ) was 7.457±2.122pmol/L and the maximum binding counts (B max ) was 2.385±0.175pmol/2.5×10 6 cells, respectively. FITC-GA bound to cytomembrane specifically and 18β-GA competed to bind the sites significantly in HepG2 cells. Therefore, there is binding effect between fluorescence labeled GA and GA-R. The GA-R on HCC cells is confirmed as expected, which provides a useful reference of active target modified by GA and a novel approach for receptors and ligands study. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Comparative Toxicogenomic Responses to the Flame Retardant mITP in Developing Zebrafish.

    PubMed

    Haggard, Derik E; Das, Siba R; Tanguay, Robert L

    2017-02-20

    Monosubstituted isopropylated triaryl phosphate (mITP) is a major component of Firemaster 550, an additive flame retardant mixture commonly used in polyurethane foams. Developmental toxicity studies in zebrafish established mITP as the most toxic component of FM 550, which causes pericardial edema and heart looping failure. Mechanistic studies showed that mITP is an aryl hydrocarbon receptor (AhR) ligand; however, the cardiotoxic effects of mITP were independent of the AhR. We performed comparative whole genome transcriptomics in wild-type and ahr2 hu3335 zebrafish, which lack functional ahr2, to identify transcriptional signatures causally involved in the mechanism of mITP-induced cardiotoxicity. Regardless of ahr2 status, mITP exposure resulted in decreased expression of transcripts related to the synthesis of all-trans-retinoic acid and a host of Hox genes. Clustered gene ontology enrichment analysis showed unique enrichment in biological processes related to xenobiotic metabolism and response to external stimuli in wild-type samples. Transcript enrichments overlapping both genotypes involved the retinoid metabolic process and sensory/visual perception biological processes. Examination of the gene-gene interaction network of the differentially expressed transcripts in both genetic backgrounds demonstrated a strong AhR interaction network specific to wild-type samples, with overlapping genes regulated by retinoic acid receptors (RARs). A transcriptome analysis of control ahr2-null zebrafish identified potential cross-talk among AhR, Nrf2, and Hif1α. Collectively, we confirmed that mITP is an AhR ligand and present evidence in support of our hypothesis that mITP's developmental cardiotoxic effects are mediated by inhibition at the RAR level.

  15. An estrogen receptor β-selective agonist inhibits non-alcoholic steatohepatitis in preclinical models by regulating bile acid and xenobiotic receptors.

    PubMed

    Ponnusamy, Suriyan; Tran, Quynh T; Thiyagarajan, Thirumagal; Miller, Duane D; Bridges, Dave; Narayanan, Ramesh

    2017-03-01

    Non-alcoholic steatohepatitis (NASH) affects 8-10 million people in the US and up to 75% of obese individuals. Despite this, there are no approved oral therapeutics to treat NASH and therefore the need for novel approaches exists. The estrogen receptor β (ER-β)-selective agonist, β-LGND2, inhibits body weight and white adipose tissue, and increases metabolism, resulting in higher energy expenditure and thermogenesis. Due to favorable effects of β-LGND2 on obesity, we hypothesized that β-LGND2 will prevent NASH directly by reducing lipid accumulation in the liver or indirectly by favorably changing body composition. Male C57BL/6 mice fed with high fat diet (HFD) for 10 weeks or methionine choline-deficient diet for four weeks and treated with vehicle exhibited altered liver weights by twofold and increased serum transaminases by 2-6-folds. These changes were not observed in β-LGND2-treated animals. Infiltration of inflammatory cells and collagen deposits, an indication of fibrosis, were observed in the liver of mice fed with HFD for 10 weeks, which were effectively blocked by β-LGND2. Gene expression studies in the liver indicate that pregnane X receptor target genes were significantly increased by HFD, and the increase was inhibited by β-LGND2. On the other hand, metabolomics indicate that bile acid metabolites were significantly increased by β-LGND2. These studies demonstrate that an ER-β agonist might provide therapeutic benefits in NASH by directly modulating the function of xenobiotic and bile acid receptors in the liver, which have important functions in the liver, and indirectly, as demonstrated before, by inhibiting adiposity. Impact statement Over 75-90% of those classified as clinically obese suffer from co-morbidities, the most common of which is non-alcoholic steatohepatitis (NASH). While there are currently no effective treatment approaches for NASH, data presented here provide preliminary evidence that an estrogen receptor β-selective ligand

  16. Removal of acidic or basic α-amino acids in water by poorly water soluble scandium complexes.

    PubMed

    Hayashi, Nobuyuki; Jin, Shigeki; Ujihara, Tomomi

    2012-11-02

    To recognize α-amino acids with highly polar side chains in water, poorly water soluble scandium complexes with both Lewis acidic and basic portions were synthesized as artificial receptors. A suspension of some of these receptor molecules in an α-amino acid solution could remove acidic and basic α-amino acids from the solution. The compound most efficient at preferentially removing basic α-amino acids (arginine, histidine, and lysine) was the receptor with 7,7'-[1,3-phenylenebis(carbonylimino)]bis(2-naphthalenesulfonate) as the ligand. The neutral α-amino acids were barely removed by these receptors. Removal experiments using a mixed amino acid solution generally gave results similar to those obtained using solutions containing a single amino acid. The results demonstrated that the scandium complex receptors were useful for binding acidic and basic α-amino acids.

  17. The effect of albumin on podocytes: The role of the fatty acid moiety and the potential role of CD36 scavenger receptor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pawluczyk, I.Z.A., E-mail: izap1@le.ac.uk; John Walls Renal Unit, Leicester General Hospital Leicester; Pervez, A.

    Evidence is emerging that podocytes are able to endocytose proteins such as albumin using kinetics consistent with a receptor-mediated process. To date the role of the fatty acid moiety on albumin uptake kinetics has not been delineated and the receptor responsible for uptake is yet to be identified. Albumin uptake studies were carried out on cultured human podocytes exposed to FITC-labelled human serum albumin either carrying fatty acids (HSA{sub +FA}) or depleted of them (HSA{sub −FA}). Receptor-mediated endocytosis of FITC-HSA{sub +FA} over 60 min was 5 times greater than that of FITC-HSA{sub −FA}. 24 h exposure of podocytes to albuminmore » up-regulated nephrin expression and induced the activation of caspase-3. These effects were more pronounced in response to HSA{sub −FA.} Individually, anti-CD36 antibodies had no effect upon endocytosis of FITC-HSA. However, a cocktail of 2 antibodies reduced uptake by nearly 50%. Albumin endocytosis was enhanced in the presence of the CD36 specific inhibitor sulfo-N-succinimidyl oleate (SSO) while knock-down of CD36 using CD36siRNA had no effect on uptake. These data suggest that receptor-mediated endocytosis of albumin by podocytes is regulated by the fatty acid moiety, although, some of the detrimental effects are induced independently of it. CD36 does not play a direct role in the uptake of albumin. - Highlights: • The fatty acid moiety is essential for receptor mediated endocytosis of albumin. • Fatty acid depleted albumin is more pathogenic to podocytes. • CD36 is not directly involved in albumin uptake by podocytes.« less

  18. Effects of physiological versus pharmacological beta-carotene supplementation on cell proliferation and histopathological changes in the lungs of cigarette smoke-exposed ferrets.

    PubMed

    Liu, C; Wang, X D; Bronson, R T; Smith, D E; Krinsky, N I; Russell, R M

    2000-12-01

    There remains a remarkable discordance between the results of observational epidemiological studies and intervention trials using beta-carotene as a potential chemopreventive agent. One question that needs to be examined is whether the adverse outcomes of human beta-carotene trials are related to the large doses of beta-carotene that were administered. In the present study, ferrets were given a physiological (low) dose or a pharmacological (high) dose of beta-carotene supplementation (0.43 mg versus 2.4 mg/kg body wt/day, which is equivalent to 6 mg versus 30 mg/day in humans) and exposed to cigarette smoke for 6 months. We investigated the effects of these doses of beta-carotene on retinoid concentrations, expression of retinoic acid receptors (RARs), activator protein 1 (AP-1; c-Jun and c-Fos), cyclin D1, proliferating cellular nuclear antigen (PCNA), and histopathological changes in the lungs of both normal and cigarette smoke-exposed ferrets. Thirty-six male ferrets were treated in six groups-control, smoke-exposed (SM), low-dose beta-carotene (LBC), high-dose beta-carotene (HBC), low-dose beta-carotene plus smoke exposure (LBC+SM) or high-dose beta-carotene plus smoke exposure (HBC+SM)-for 6 months. Retinoic acid concentration and RAR beta gene expression, but not expression of RAR alpha and RAR gamma, was reduced in the lung tissue of HBC+SM, HBC, SM and LBC+SM ferrets, but not in that of LBC ferrets, as compared with the control group. Expression of AP-1 and PCNA was greater in HBC+SM, HBC, SM and LBC+SM ferrets, but not in the LBC ferrets, as compared with the control group. Increased amounts of cyclin D1 and keratinized squamous metaplasia were observed in the lung tissue of HBC+SM, HBC and SM groups but not in that of the LBC+SM, LBC or control groups. These data suggest that, in contrast with a pharmacological dose of beta-carotene, a physiological dose of beta-carotene in smoke-exposed ferrets has no potentially detrimental effects and may afford weak

  19. A survey of the pyrabactin resistance-like abscisic acid receptor gene family in poplar.

    PubMed

    Yu, Jingling; Li, Hejuan; Peng, Yajing; Yang, Lei; Zhao, Fugeng; Luan, Sheng; Lan, Wenzhi

    2017-08-03

    The conserved PYR/PYL/RCAR family acts as abscisic acid (ABA) receptors for land plants to adapt to terrestrial environments. Our recent study reported that the exogenous overexpression of poplar PtPYRL1 and PtPYRL5, the PYR/PYL/RCAR orthologs, promoted the sensitivity of transgenic Arabidopsis to ABA responses. Here, we surveyed the PtPYRL family in poplar, and revealed that although the sequence and structure are relatively conserved among these receptors, PtPYRL members have differential expression patterns and the sensitivity to ABA or drought treatment, suggesting that PtPYRLs might be good candidates to a future biotechnological use to enhance poplar resistance to water-stress environments.

  20. Ondansetron and granisetron binding orientation in the 5-HT(3) receptor determined by unnatural amino acid mutagenesis.

    PubMed

    Duffy, Noah H; Lester, Henry A; Dougherty, Dennis A

    2012-10-19

    The serotonin type 3 receptor (5-HT(3)R) is a ligand-gated ion channel found in the central and peripheral nervous systems. The 5-HT(3)R is a therapeutic target, and the clinically available drugs ondansetron and granisetron inhibit receptor activity. Their inhibitory action is through competitive binding to the native ligand binding site, although the binding orientation of the drugs at the receptor has been a matter of debate. Here we heterologously express mouse 5-HT(3)A receptors in Xenopus oocytes and use unnatural amino acid mutagenesis to establish a cation-π interaction for both ondansetron and granisetron to tryptophan 183 in the ligand binding pocket. This cation-π interaction establishes a binding orientation for both ondansetron and granisetron within the binding pocket.

  1. Evolutionary Analysis of Functional Divergence among Chemokine Receptors, Decoy Receptors, and Viral Receptors

    PubMed Central

    Daiyasu, Hiromi; Nemoto, Wataru; Toh, Hiroyuki

    2012-01-01

    Chemokine receptors (CKRs) function in the inflammatory response and in vertebrate homeostasis. Decoy and viral receptors are two types of CKR homologs with modified functions from those of the typical CKRs. The decoy receptors are able to bind ligands without signaling. On the other hand, the viral receptors show constitutive signaling without ligands. We examined the sites related to the functional difference. At first, the decoy and viral receptors were each classified into five groups, based on the molecular phylogenetic analysis. A multiple amino acid sequence alignment between each group and the CKRs was then constructed. The difference in the amino acid composition between the group and the CKRs was evaluated as the Kullback–Leibler (KL) information value at each alignment site. The KL information value is considered to reflect the difference in the functional constraints at the site. The sites with the top 5% of KL information values were selected and mapped on the structure of a CKR. The comparisons with decoy receptor groups revealed that the detected sites were biased on the intracellular side. In contrast, the sites detected from the comparisons with viral receptor groups were found on both the extracellular and intracellular sides. More sites were found in the ligand binding pocket in the analyses of the viral receptor groups, as compared to the decoy receptor groups. Some of the detected sites were located in the GPCR motifs. For example, the DRY motif of the decoy receptors was often degraded, although the motif of the viral receptors was basically conserved. The observations for the viral receptor groups suggested that the constraints in the pocket region are loose and that the sites on the intracellular side are different from those for the decoy receptors, which may be related to the constitutive signaling activity of the viral receptors. PMID:22855685

  2. Evolutionary Analysis of Functional Divergence among Chemokine Receptors, Decoy Receptors, and Viral Receptors.

    PubMed

    Daiyasu, Hiromi; Nemoto, Wataru; Toh, Hiroyuki

    2012-01-01

    Chemokine receptors (CKRs) function in the inflammatory response and in vertebrate homeostasis. Decoy and viral receptors are two types of CKR homologs with modified functions from those of the typical CKRs. The decoy receptors are able to bind ligands without signaling. On the other hand, the viral receptors show constitutive signaling without ligands. We examined the sites related to the functional difference. At first, the decoy and viral receptors were each classified into five groups, based on the molecular phylogenetic analysis. A multiple amino acid sequence alignment between each group and the CKRs was then constructed. The difference in the amino acid composition between the group and the CKRs was evaluated as the Kullback-Leibler (KL) information value at each alignment site. The KL information value is considered to reflect the difference in the functional constraints at the site. The sites with the top 5% of KL information values were selected and mapped on the structure of a CKR. The comparisons with decoy receptor groups revealed that the detected sites were biased on the intracellular side. In contrast, the sites detected from the comparisons with viral receptor groups were found on both the extracellular and intracellular sides. More sites were found in the ligand binding pocket in the analyses of the viral receptor groups, as compared to the decoy receptor groups. Some of the detected sites were located in the GPCR motifs. For example, the DRY motif of the decoy receptors was often degraded, although the motif of the viral receptors was basically conserved. The observations for the viral receptor groups suggested that the constraints in the pocket region are loose and that the sites on the intracellular side are different from those for the decoy receptors, which may be related to the constitutive signaling activity of the viral receptors.

  3. Efficient modulation of γ-aminobutyric acid type A receptors by piperine derivatives.

    PubMed

    Schöffmann, Angela; Wimmer, Laurin; Goldmann, Daria; Khom, Sophia; Hintersteiner, Juliane; Baburin, Igor; Schwarz, Thomas; Hintersteininger, Michael; Pakfeifer, Peter; Oufir, Mouhssin; Hamburger, Matthias; Erker, Thomas; Ecker, Gerhard F; Mihovilovic, Marko D; Hering, Steffen

    2014-07-10

    Piperine activates TRPV1 (transient receptor potential vanilloid type 1 receptor) receptors and modulates γ-aminobutyric acid type A receptors (GABAAR). We have synthesized a library of 76 piperine analogues and analyzed their effects on GABAAR by means of a two-microelectrode voltage-clamp technique. GABAAR were expressed in Xenopus laevis oocytes. Structure-activity relationships (SARs) were established to identify structural elements essential for efficiency and potency. Efficiency of piperine derivatives was significantly increased by exchanging the piperidine moiety with either N,N-dipropyl, N,N-diisopropyl, N,N-dibutyl, p-methylpiperidine, or N,N-bis(trifluoroethyl) groups. Potency was enhanced by replacing the piperidine moiety by N,N-dibutyl, N,N-diisobutyl, or N,N-bistrifluoroethyl groups. Linker modifications did not substantially enhance the effect on GABAAR. Compound 23 [(2E,4E)-5-(1,3-benzodioxol-5-yl)-N,N-dipropyl-2,4-pentadienamide] induced the strongest modulation of GABAA (maximal GABA-induced chloride current modulation (IGABA-max = 1673% ± 146%, EC50 = 51.7 ± 9.5 μM), while 25 [(2E,4E)-5-(1,3-benzodioxol-5-yl)-N,N-dibutyl-2,4-pentadienamide] displayed the highest potency (EC50 = 13.8 ± 1.8 μM, IGABA-max = 760% ± 47%). Compound 23 induced significantly stronger anxiolysis in mice than piperine and thus may serve as a starting point for developing novel GABAAR modulators.

  4. WHIM syndrome caused by a single amino acid substitution in the carboxy-tail of chemokine receptor CXCR4

    PubMed Central

    Liu, Qian; Chen, Haoqian; Ojode, Teresa; Gao, Xiangxi; Anaya-O'Brien, Sandra; Turner, Nicholas A.; Ulrick, Jean; DeCastro, Rosamma; Kelly, Corin; Cardones, Adela R.; Gold, Stuart H.; Hwang, Eugene I.; Wechsler, Daniel S.; Malech, Harry L.; Murphy, Philip M.

    2012-01-01

    WHIM syndrome is a rare, autosomal dominant, immunodeficiency disorder so-named because it is characterized by warts, hypogammaglobulinemia, infections, and myelokathexis (defective neutrophil egress from the BM). Gain-of-function mutations that truncate the C-terminus of the chemokine receptor CXCR4 by 10-19 amino acids cause WHIM syndrome. We have identified a family with autosomal dominant inheritance of WHIM syndrome that is caused by a missense mutation in CXCR4, E343K (1027G → A). This mutation is also located in the C-terminal domain, a region responsible for negative regulation of the receptor. Accordingly, like CXCR4R334X, the most common truncation mutation in WHIM syndrome, CXCR4E343K mediated approximately 2-fold increased signaling in calcium flux and chemotaxis assays relative to wild-type CXCR4; however, CXCR4E343K had a reduced effect on blocking normal receptor down-regulation from the cell surface. Therefore, in addition to truncating mutations in the C-terminal domain of CXCR4, WHIM syndrome may be caused by a single charge-changing amino acid substitution in this domain, E343K, that results in increased receptor signaling. PMID:22596258

  5. Altered Levels of Zinc and N-methyl-D-aspartic Acid Receptor Underlying Multiple Organ Dysfunctions After Severe Trauma

    PubMed Central

    Wang, Guanghuan; Yu, Xiaojun; Wang, Dian; Xu, Xiaohu; Chen, Guang; Jiang, Xuewu

    2015-01-01

    Background Severe trauma can cause secondary multiple organ dysfunction syndrome (MODS) and death. Oxidative stress and/or excitatory neurotoxicity are considered as the final common pathway in nerve cell injuries. Zinc is the cofactor of the redox enzyme, and the effect of the excitatory neurotoxicity is related to N-methyl-D-aspartic acid receptor (NMDAR). Material/Methods We investigated the levels of zinc and brainstem NMDAR in a rabbit model of severe trauma. Zinc and serum biochemical profiles were determined. Immunohistochemistry was used to detect brainstem N-methyl-D-aspartic acid receptor 1 (NR1), N-methyl-D-aspartic acid receptor 2A (NR2A), and N-methyl-D-aspartic acid receptor 2B (NR2B) expression. Results Brain and brainstem Zn levels increased at 12 h, but serum Zn decreased dramatically after the trauma. NR1 in the brainstem dorsal regions increased at 6 h after injury and then decreased. NR2A in the dorsal regions decreased to a plateau at 12 h after trauma. The levels of NR2B were lowest in the death group in the brainstem. Serum zinc was positively correlated with NR2A and 2B and negatively correlated with zinc in the brain. Correlations were also found between the brainstem NR2A and that of the dorsal brainstem, as well as between brainstem NR2A and changes in NR2B. There was a negative correlation between zinc and NR2A. Conclusions Severe trauma led to an acute reduction of zinc enhancing oxidative stress and the changes of NMDAR causing the neurotoxicity of the nerve cells. This may be a mechanism for the occurrence of MODS or death after trauma. PMID:26335029

  6. Medium-chain fatty acids as ligands for orphan G protein-coupled receptor GPR84.

    PubMed

    Wang, Jinghong; Wu, Xiaosu; Simonavicius, Nicole; Tian, Hui; Ling, Lei

    2006-11-10

    Free fatty acids (FFAs) play important physiological roles in many tissues as an energy source and as signaling molecules in various cellular processes. Elevated levels of circulating FFAs are associated with obesity, dyslipidemia, and diabetes. Here we show that GPR84, a previously orphan G protein-coupled receptor, functions as a receptor for medium-chain FFAs with carbon chain lengths of 9-14. Medium-chain FFAs elicit calcium mobilization, inhibit 3',5'-cyclic AMP production, and stimulate [35S]guanosine 5'-O-(3-thiotriphosphate) binding in a GPR84-dependent manner. The activation of GPR84 by medium-chain FFAs couples primarily to a pertussis toxin-sensitive G(i/o) pathway. In addition, we show that GPR84 is selectively expressed in leukocytes and markedly induced in monocytes/macrophages upon activation by lipopolysaccharide. Furthermore, we demonstrate that medium-chain FFAs amplify lipopolysaccharide-stimulated production of the proinflammatory cytokine interleukin-12 p40 through GPR84. Our results indicate a role for GPR84 in directly linking fatty acid metabolism to immunological regulation.

  7. Endogenous fatty acid ethanolamides suppress nicotine-induced activation of mesolimbic dopamine neurons through nuclear receptors.

    PubMed

    Melis, Miriam; Pillolla, Giuliano; Luchicchi, Antonio; Muntoni, Anna Lisa; Yasar, Sevil; Goldberg, Steven R; Pistis, Marco

    2008-12-17

    Nicotine stimulates the activity of mesolimbic dopamine neurons, which is believed to mediate the rewarding and addictive properties of tobacco use. Accumulating evidence suggests that the endocannabinoid system might play a major role in neuronal mechanisms underlying the rewarding properties of drugs of abuse, including nicotine. Here, we investigated the modulation of nicotine effects by the endocannabinoid system on dopamine neurons in the ventral tegmental area with electrophysiological techniques in vivo and in vitro. We discovered that pharmacological inhibition of fatty acid amide hydrolase (FAAH), the enzyme that catabolizes fatty acid ethanolamides, among which the endocannabinoid anandamide (AEA) is the best known, suppressed nicotine-induced excitation of dopamine cells. Importantly, this effect was mimicked by the administration of the FAAH substrates oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), but not methanandamide, the hydrolysis resistant analog of AEA. OEA and PEA are naturally occurring lipid signaling molecules structurally related to AEA, but devoid of affinity for cannabinoid receptors. They blocked the effects of nicotine by activation of the peroxisome proliferator-activated receptor-alpha (PPAR-alpha), a nuclear receptor transcription factor involved in several aspects of lipid metabolism and energy balance. Activation of PPAR-alpha triggered a nongenomic stimulation of tyrosine kinases, which might lead to phosphorylation and negative regulation of neuronal nicotinic acetylcholine receptors. These data indicate for the first time that the anorexic lipids OEA and PEA possess neuromodulatory properties as endogenous ligands of PPAR-alpha in the brain and provide a potential new target for the treatment of nicotine addiction.

  8. QUANTITATION OF ABERRANT INTERLOCUS T-CELL RECEPTOR REARRANGEMENTS IN MOUSE THYMOCYTES AND THE EFFECT OF THE HERBICIDE 2,4- DICHLOROPHENOXYACETIC ACID

    EPA Science Inventory

    Quantitation of aberrant interlocus T-cell receptor rearrangements in mouse thymocytes and the effect of the herbicide 2,4- Dichlorophenoxyacetic acid

    Small studies in human populations have suggested a correlation between the frequency of errors in antigen receptor gene a...

  9. Lung vagal afferent activity in rats with bleomycin-induced lung fibrosis.

    PubMed

    Schelegle, E S; Walby, W F; Mansoor, J K; Chen, A T

    2001-05-01

    Bleomycin treatment in rats results in pulmonary fibrosis that is characterized by a rapid shallow breathing pattern, a decrease in quasi-static lung compliance and a blunting of the Hering-Breuer Inflation Reflex. We examined the impulse activity of pulmonary vagal afferents in anesthetized, mechanically ventilated rats with bleomycin-induced lung fibrosis during the ventilator cycle and static lung inflations/deflations and following the injection of capsaicin into the right atrium. Bleomycin enhanced volume sensitivity of slowly adapting stretch receptors (SARs), while it blunted the sensitivity of these receptors to increasing transpulmonary pressure. Bleomycin treatment increased the inspiratory activity, while it decreased the expiratory activity of rapidly adapting stretch receptors (RARs). Pulmonary C-fiber impulse activity did not appear to be affected by bleomycin treatment. We conclude that the fibrosis-related shift in discharge profile and enhanced volume sensitivity of SARs combined with the increased inspiratory activity of RARs contributes to the observed rapid shallow breathing of bleomycin-induced lung fibrosis.

  10. Identification of amino acids in the transmembrane and juxtamembrane domains of the platelet-derived growth factor receptor required for productive interaction with the bovine papillomavirus E5 protein.

    PubMed

    Petti, L M; Reddy, V; Smith, S O; DiMaio, D

    1997-10-01

    The bovine papillomavirus E5 protein forms a stable complex with the cellular platelet-derived growth factor (PDGF) beta receptor, resulting in receptor activation and cell transformation. Amino acids in both the putative transmembrane domain and extracytoplasmic carboxyl-terminal domain of the E5 protein appear important for PDGF receptor binding and activation. Previous analysis indicated that the transmembrane domain of the receptor was also required for complex formation and receptor activation. Here we analyzed receptor chimeras and point mutants to identify specific amino acids in the PDGF beta receptor required for productive interaction with the E5 protein. These receptor mutants were analyzed in murine Ba/F3 cells, which do not express endogenous receptor. Our results confirmed the importance of the transmembrane domain of the receptor for complex formation, receptor tyrosine phosphorylation, and mitogenic signaling in response to the E5 protein and established that the threonine residue in this domain is required for these activities. In addition, a positive charge in the extracellular juxtamembrane domain of the receptor was required for E5 interaction and signaling, whereas replacement of the wild-type lysine with either a neutral or acidic amino acid inhibited E5-induced receptor activation and transformation. All of the receptor mutants defective for activation by the E5 protein responded to acute treatment with PDGF and to stable expression of v-Sis, a form of PDGF. The required juxtamembrane lysine and transmembrane threonine are predicted to align precisely on the same face of an alpha helix packed in a left-handed coiled-coil geometry. These results establish that the E5 protein and v-Sis recognize distinct binding sites on the PDGF beta receptor and further clarify the nature of the interaction between the viral transforming protein and its cellular target.

  11. Maslinic acid ameliorates NMDA receptor blockade-induced schizophrenia-like behaviors in mice.

    PubMed

    Jeon, Se Jin; Kim, Eunji; Lee, Jin Su; Oh, Hee Kyong; Zhang, Jiabao; Kwon, Yubeen; Jang, Dae Sik; Ryu, Jong Hoon

    2017-11-01

    Schizophrenia is a chronic psychotic disorder characterized by positive, negative, and cognitive symptoms. Primary treatments for schizophrenia relieve the positive symptoms but are less effective against the negative and cognitive symptoms. In the present study, we investigated whether maslinic acid, isolated from Syzygium aromaticum (clove), can ameliorate schizophrenia-like behaviors in mice induced by MK-801, an N-methyl-d-aspartate (NMDA) receptor antagonist. After maslinic acid treatment in the MK-801 model, we examined the behavioral alteration and signaling pathways in the prefrontal cortex. Mice were treated with maslinic acid (30 mg/kg), and their behaviors were evaluated through an array of behavioral tests. The effects of maslinic acid were also examined in the signaling pathways in the prefrontal cortex. A single administration of maslinic acid blocked the MK-801-induced hyperlocomotion and reversed the MK-801-induced sensorimotor gating deficit in the acoustic startle response test. In the social novelty preference test, maslinic acid ameliorated the social behavior deficits induced by MK-801. The MK-801-induced attention and recognition memory impairments were also alleviated by a single administration of maslinic acid. Furthermore, maslinic acid normalized the phosphorylation levels of Akt-GSK-3β and ERK-CREB in the prefrontal cortex. Overall, maslinic acid ameliorated the schizophrenia-like symptoms induced by MK-801, and these effects may be partly mediated through Akt-GSK-3β and ERK-CREB activation. These findings suggest that maslinic acid could be a candidate for the treatment of several symptoms of schizophrenia, including positive symptoms, sensorimotor gating disruption, social interaction deficits, and cognitive impairments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Glycyrrhizic acid prevents high calorie diet-induced metabolic aberrations despite the suppression of peroxisome proliferator-activated receptor γ expression.

    PubMed

    Cheng, Hong Sheng; Yaw, Hui Ping; Ton, So Ha; Choy, Siew Mei; Kong, Joana Magdelene Xiao Fang; Abdul Kadir, Khalid

    2016-09-01

    To investigate the effects of glycyrrhizic acid supplementation on glucose and lipid metabolism in rodents consuming a high-fat, high-sucrose diet. Twenty-four male, 8-week old Sprague Dawley rats with an initial weight of 160 to 200 g were randomised into three groups (n = 6 for each group): groups A (standard rat chow), B (high-fat, high-sucrose diet), and C (high-fat, high-sucrose diet + 100 mg/kg/d of glycyrrhizic acid via oral administration). The rats were treated accordingly for 4 wk. Glycaemic parameters, lipid profile, stress hormones, and adiponectin levels were measured after the treatment. Relative gene expressions of peroxisome proliferator-activated receptor α and γ, lipoprotein lipase as well as gluconeogenic enzymatic activities in different tissues were also determined. Consumption of high-fat, high-sucrose diet triggered hyperglycaemia, insulin resistance, and dyslipidemia, which were effectively attenuated by supplementation with glycyrrhizic acid. Glycyrrhizic acid supplementation also effectively reduced circulating adrenaline, alleviated gluconeogenic enzymes overactivity, and promoted the upregulation of lipoprotein lipase expression in the cardiomyocytes and skeletal muscles. A high calorie diet also triggered hypoadiponectinaemia and suppression of peroxisome proliferator-activated receptor γ expression, which did not improve with glycyrrhizic acid treatment. Supplementation with glycyrrhizic acid could alleviate high calorie diet-induced glucose and lipid metabolic dysregulations by reducing circulatory stress hormones, normalizing gluconeogenic enzyme activities, and elevating muscular lipid uptake. The beneficial effects of these bioactivities outweighed the adverse effects caused by diet-induced repression of peroxisome proliferator-activated receptor γ expression, resulting in the maintenance of lipid and glucose homeostasis. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Expression pattern of the type 1 sigma receptor in the brain and identity of critical anionic amino acid residues in the ligand-binding domain of the receptor.

    PubMed

    Seth, P; Ganapathy, M E; Conway, S J; Bridges, C D; Smith, S B; Casellas, P; Ganapathy, V

    2001-07-25

    The type 1 sigma receptor (sigmaR1) has been shown to participate in a variety of functions in the central nervous system. To identify the specific regions of the brain that are involved in sigmaR1 function, we analyzed the expression pattern of the receptor mRNA in the mouse brain by in situ hybridization. SigmaR1 mRNA was detectable primarily in the cerebral cortex, hippocampus, and Purkinje cells of cerebellum. To identify the critical anionic amino acid residues in the ligand-binding domain of sigmaR1, we employed two different approaches: chemical modification of anionic amino acid residues and site-directed mutagenesis. Chemical modification of anionic amino acids in sigmaR1 with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide reduced the ligand-binding activity markedly. Since it is known that a splice variant of this receptor which lacks exon 3 does not have the ability to bind sigma ligands, the ligand-binding domain with its critical anionic amino acid residues is likely to be present in or around the region coded by exon 3. Therefore, each of the anionic amino acids in this region was mutated individually and the influence of each mutation on ligand binding was assessed. These studies have identified two anionic amino acids, D126 and E172, that are obligatory for ligand binding. Even though the ligand-binding function was abolished by these two mutations, the expression of these mutants was normal at the protein level. These results show that sigmaR1 is expressed at high levels in specific areas of the brain that are involved in memory, emotion and motor functions. The results also provide important information on the chemical nature of the ligand-binding site of sigmaR1 that may be of use in the design of sigmaR1-specific ligands with potential for modulation of sigmaR1-related brain functions.

  14. Mesodermal retinoic acid signaling regulates endothelial cell coalescence in caudal pharyngeal arch artery vasculogenesis

    PubMed Central

    Li, Peng; Pashmforoush, Mohammad; Sucov, Henry M.

    2011-01-01

    Disruption of retinoic acid signaling causes a variety of pharyngeal arch artery and great vessel defects, as well as malformations in many other tissues, including those derived from the pharyngeal endoderm. Previous studies implied that arch artery defects in the context of defective RA signaling occur secondary to pharyngeal pouch segmentation defects, although this model has never been experimentally verified. In this study, we examined arch artery morphogenesis during mouse development, and the role of RA in this process. We show in normal embryos that the arch arteries form by vasculogenic differentiation of pharyngeal mesoderm. Using various genetic backgrounds and tissue-specific mutation approaches, we segregate pharyngeal arch artery and pharyngeal pouch defects in RA receptor mutants, and show that RA signal transduction only in pharyngeal mesoderm is required for arch artery formation. RA does not control pharyngeal mesodermal differentiation to endothelium, but instead promotes the aggregation of endothelial cells into nascent vessels. Expression of VE-cadherin was substantially reduced in RAR mutants, and this deficiency may underlie the arch artery defects. The consequences of disrupted mesodermal and endodermal RA signaling were restricted to the 4th and 6th arch arteries and to the 4th pharyngeal pouch, respectively, suggesting that different regulatory mechanisms control the formation of the more anterior arch arteries and pouches. PMID:22040871

  15. Ondansetron and Granisetron Binding Orientation in the 5-HT3 Receptor Determined by Unnatural Amino Acid Mutagenesis

    PubMed Central

    Duffy, Noah H.; Lester, Henry A.; Dougherty, Dennis A.

    2012-01-01

    The serotonin type 3 receptor (5-HT3R) is a ligand-gated ion channel that mediates fast synaptic transmission in the central and peripheral nervous systems. The 5-HT3R is a therapeutic target, and the clinically available drugs ondansetron and granisetron inhibit receptor activity. Their inhibitory action is through competitive binding to the native ligand binding site, although the binding orientation of the drugs at the receptor has been a matter of debate. Here we heterologously express mouse 5-HT3A receptors in Xenopus oocytes and use unnatural amino acid mutagenesis to establish a cation-π interaction for both ondansetron and granisetron to tryptophan 183 in the ligand binding pocket. This cation-π interaction establishes a binding orientation for both ondansetron and granisetron within the binding pocket. PMID:22873819

  16. G-protein-coupled receptors for neurotransmitter amino acids: C-terminal tails, crowded signalosomes.

    PubMed Central

    El Far, Oussama; Betz, Heinrich

    2002-01-01

    G-protein-coupled receptors (GPCRs) represent a superfamily of highly diverse integral membrane proteins that transduce external signals to different subcellular compartments, including nuclei, via trimeric G-proteins. By differential activation of diffusible G(alpha) and membrane-bound G(beta)gamma subunits, GPCRs might act on both cytoplasmic/intracellular and plasma-membrane-bound effector systems. The coupling efficiency and the plasma membrane localization of GPCRs are regulated by a variety of interacting proteins. In this review, we discuss recently disclosed protein interactions found with the cytoplasmic C-terminal tail regions of two types of presynaptic neurotransmitter receptors, the group III metabotropic glutamate receptors and the gamma-aminobutyric acid type-B receptors (GABA(B)Rs). Calmodulin binding to mGluR7 and other group III mGluRs may provide a Ca(2+)-dependent switch for unidirectional (G(alpha)) versus bidirectional (G(alpha) and G(beta)gamma) signalling to downstream effector proteins. In addition, clustering of mGluR7 by PICK1 (protein interacting with C-kinase 1), a polyspecific PDZ (PSD-95/Dlg1/ZO-1) domain containing synaptic organizer protein, sheds light on how higher-order receptor complexes with regulatory enzymes (or 'signalosomes') could be formed. The interaction of GABA(B)Rs with the adaptor protein 14-3-3 and the transcription factor ATF4 (activating transcription factor 4) suggests novel regulatory pathways for G-protein signalling, cytoskeletal reorganization and nuclear gene expression: processes that may all contribute to synaptic plasticity. PMID:12006104

  17. Structural analysis of binding functionality of folic acid-PEG dendrimers against folate receptor.

    PubMed

    Sampogna-Mireles, Diana; Araya-Durán, Ingrid D; Márquez-Miranda, Valeria; Valencia-Gallegos, Jesús A; González-Nilo, Fernando D

    2017-03-01

    Dendrimers functionalized with folic acid (FA) are drug delivery systems that can selectively target cancer cells with folate receptors (FR-α) overexpression. Incorporation of polyethylene glycol (PEG) can enhance dendrimers solubility and pharmacokinetics, but ligand-receptor binding must not be affected. In this work we characterized, at atomic level, the binding functionality of conventional site-specific dendrimers conjugated with FA with PEG 750 or PEG 3350 as a linker. After Molecular Dynamics simulation, we observed that both PEG's did not interfere over ligand-receptor binding functionality. Although binding kinetics could be notably affected, the folate fragment from both dendrimers remained exposed to the solvent before approaching selectively to FR-α. PEG 3350 provided better solubility and protection from enzymatic degradation to the dendrimer than PEG 750. Also, FA-PEG3350 dendrimer showed a slightly better interaction with FR-α than FA-PEG750 dendrimer. Therefore, theoretical evidence supports that both dendrimers are suitable as drug delivery systems for cancer therapies. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Inhibition of strigolactone receptors by N-phenylanthranilic acid derivatives: Structural and functional insights.

    PubMed

    Hamiaux, Cyril; Drummond, Revel S M; Luo, Zhiwei; Lee, Hui Wen; Sharma, Prachi; Janssen, Bart J; Perry, Nigel B; Denny, William A; Snowden, Kimberley C

    2018-04-27

    The strigolactone (SL) family of plant hormones regulates a broad range of physiological processes affecting plant growth and development and also plays essential roles in controlling interactions with parasitic weeds and symbiotic fungi. Recent progress elucidating details of SL biosynthesis, signaling, and transport offers many opportunities for discovering new plant-growth regulators via chemical interference. Here, using high-throughput screening and downstream biochemical assays, we identified N -phenylanthranilic acid derivatives as potent inhibitors of the SL receptors from petunia (DAD2), rice (OsD14), and Arabidopsis (AtD14). Crystal structures of DAD2 and OsD14 in complex with inhibitors further provided detailed insights into the inhibition mechanism, and in silico modeling of 19 other plant strigolactone receptors suggested that these compounds are active across a large range of plant species. Altogether, these results provide chemical tools for investigating SL signaling and further define a framework for structure-based approaches to design and validate optimized inhibitors of SL receptors for specific plant targets. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Regulating the Efficacy of Inhibition Through Trafficking of γ-Aminobutyric Acid Type A Receptors.

    PubMed

    Vien, Thuy N; Moss, Stephen J; Davies, Paul A

    2016-11-01

    Trafficking of anesthetic-sensitive receptors within the plasma membrane, or from one cellular component to another, occurs continuously. Changes in receptor trafficking have implications in altering anesthetic sensitivity. γ-Aminobutyric acid type A receptors (GABAARs) are anion-permeable ion channels and are the major class of receptor in the adult mammalian central nervous system that mediates inhibition. GABAergic signaling allows for precise synchronized firing of action potentials within brain circuits that is critical for cognition, behavior, and consciousness. This precision depends upon tightly controlled trafficking of GABAARs into the membrane. General anesthetics bind to and allosterically enhance GABAARs by prolonging the open state of the receptor and thereby altering neuronal and brain circuit activity. Subunit composition and GABAAR localization strongly influence anesthetic end points; therefore, changes in GABAAR trafficking could have significant consequences to anesthetic sensitivity. GABAARs are not static membrane structures but are in a constant state of flux between extrasynaptic and synaptic locations and are continually endocytosed and recycled from and to the membrane. Neuronal activity, posttranslational modifications, and some naturally occurring and synthetic compounds can influence the expression and trafficking of GABAARs. In this article, we review GABAARs, their trafficking, and how phosphorylation of GABAAR subunits can influence the surface expression and function of the receptor. Ultimately, alterations of GABAAR trafficking could modify anesthetic end points, both unintentionally through pathologic processes but potentially as a therapeutic target to adjust anesthetic-sensitive GABAARs.

  20. Receptor binding proteins of Listeria monocytogenes bacteriophages A118 and P35 recognize serovar-specific teichoic acids

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bielmann, Regula; Habann, Matthias; Eugster, Marcel R.

    Adsorption of a bacteriophage to the host requires recognition of a cell wall-associated receptor by a receptor binding protein (RBP). This recognition is specific, and high affinity binding is essential for efficient virus attachment. The molecular details of phage adsorption to the Gram-positive cell are poorly understood. We present the first description of receptor binding proteins and a tail tip structure for the siphovirus group infecting Listeria monocytogenes. The host-range determining factors in two phages, A118 and P35 specific for L. monocytogenes serovar 1/2 have been determined. Two proteins were identified as RBPs in phage A118. Rhamnose residues in wallmore » teichoic acids represent the binding ligands for both proteins. In phage P35, protein gp16 could be identified as RBP and the role of both rhamnose and N-acetylglucosamine in phage adsorption was confirmed. Immunogold-labeling and transmission electron microscopy allowed the creation of a topological model of the A118 phage tail. - Highlights: • We present the first description of receptor binding proteins and a tail tip structure for the Siphovirus group infecting Listeria monocytogenes. • The host-range determining factors in two phages, A118 and P35 specific for L. monocytogenes serovar 1/2 have been determined. • Rhamnose residues in wall teichoic acids represent the binding ligands for both receptor binding proteins in phage A118. • Rhamnose and N-acetylglucosamine are required for adsorption of phage P35. • We preset a topological model of the A118 phage tail.« less

  1. Evidence for a central 5-hydroxytryptamine receptor stimulation by lysergic acid diethylamide

    PubMed Central

    Andén, N.-E.; Corrodi, H.; Fuxe, K.; Hökfelt, T.

    1968-01-01

    1. Lysergic acid diethylamide (LSD) and the 5-hydroxytryptamine (5-HT) precursor, 5-hydroxytryptophan produced similar functional effects in rat spinal cord and brain to the 5-hydroxytryptamine precursor 5-hydroxytryptophan, which indicates that LSD stimulates central 5-HT receptors. 2. By means of combined histochemical and biochemical techniques it was found that LSD reduced the turnover rate of brain and spinal cord 5-HT, studied after inhibition of the tryptophan hydroxylase by α-propyldopacetamide. The turnover of brain noradrenaline but not dopamine was somewhat accelerated. 3. The functional and chemical effects by LSD were related to dose and to time. They were not observed after the LSD analogues 2-bromo-LSD and methylsergide. 4. The retardation of the 5-HT turnover by LSD may be due to negative feed-back mechanisms evoked by direct stimulation of the central 5-HT receptors. ImagesFIG. 1FIG. 2 PMID:5302837

  2. Efficient Modulation of γ-Aminobutyric Acid Type A Receptors by Piperine Derivatives

    PubMed Central

    2014-01-01

    Piperine activates TRPV1 (transient receptor potential vanilloid type 1 receptor) receptors and modulates γ-aminobutyric acid type A receptors (GABAAR). We have synthesized a library of 76 piperine analogues and analyzed their effects on GABAAR by means of a two-microelectrode voltage-clamp technique. GABAAR were expressed in Xenopus laevis oocytes. Structure–activity relationships (SARs) were established to identify structural elements essential for efficiency and potency. Efficiency of piperine derivatives was significantly increased by exchanging the piperidine moiety with either N,N-dipropyl, N,N-diisopropyl, N,N-dibutyl, p-methylpiperidine, or N,N-bis(trifluoroethyl) groups. Potency was enhanced by replacing the piperidine moiety by N,N-dibutyl, N,N-diisobutyl, or N,N-bistrifluoroethyl groups. Linker modifications did not substantially enhance the effect on GABAAR. Compound 23 [(2E,4E)-5-(1,3-benzodioxol-5-yl)-N,N-dipropyl-2,4-pentadienamide] induced the strongest modulation of GABAA (maximal GABA-induced chloride current modulation (IGABA-max = 1673% ± 146%, EC50 = 51.7 ± 9.5 μM), while 25 [(2E,4E)-5-(1,3-benzodioxol-5-yl)-N,N-dibutyl-2,4-pentadienamide] displayed the highest potency (EC50 = 13.8 ± 1.8 μM, IGABA-max = 760% ± 47%). Compound 23 induced significantly stronger anxiolysis in mice than piperine and thus may serve as a starting point for developing novel GABAAR modulators. PMID:24905252

  3. ω3-Polyunsaturated fatty acids for heart failure: Effects of dose on efficacy and novel signaling through free fatty acid receptor 4.

    PubMed

    O'Connell, Timothy D; Block, Robert C; Huang, Shue P; Shearer, Gregory C

    2017-02-01

    Heart failure (HF) affects 5.7 million in the U.S., and despite well-established pharmacologic therapy, the 5-year mortality rate remains near 50%. Furthermore, the mortality rate for HF has not declined in years, highlighting the need for new therapeutic options. Omega-3 polyunsaturated fatty acids (ω3-PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are important regulators of cardiovascular health. However, questions of efficacy and mechanism of action have made the use of ω3-PUFAs in all cardiovascular disease (CVD) controversial. Here, we review recent studies in animal models of HF indicating that ω3-PUFAs, particularly EPA, are cardioprotective, with the results indicating a threshold for efficacy. We also examine clinical studies suggesting that ω3-PUFAs improve outcomes in patients with HF. Due to the relatively small number of clinical studies of ω3-PUFAs in HF, we discuss EPA concentration-dependency on outcomes in clinical trials of CVD to gain insight into the perceived questionable efficacy of ω3-PUFAs clinically, with the results again indicating a threshold for efficacy. Ultimately, we suggest that the main failing of ω3-PUFAs in clinical trials might be a failure to reach a therapeutically effective concentration. We also examine mechanistic studies suggesting that ω3-PUFAs signal through free fatty acid receptor 4 (Ffar4), a G-protein coupled receptor (GPR) for long-chain fatty acids (FA), thereby identifying an entirely novel mechanism of action for ω3-PUFA mediated cardioprotection. Finally, based on mechanistic animal studies suggesting that EPA prevents interstitial fibrosis and diastolic dysfunction, we speculate about a potential benefit for EPA-Ffar4 signaling in heart failure preserved with ejection fraction. Copyright © 2016. Published by Elsevier Ltd.

  4. Fatty acid receptor GPR120: a novel marker for human melanoma.

    PubMed

    Kleemann, Johannes; Hrgovic, Igor; Ter-Nedden, Jan; Kleimann, Pia; Steinhorst, Katja; Härle, Katja; Müller, Jutta; Kaufmann, Roland; Meissner, Markus; Kippenberger, Stefan

    2018-03-21

    The correlation between ultraviolet radiation of the skin and melanoma incidence in humans is well established. Interestingly, epidemiologic data suggest also a correlation to an increased BMI pointing to metabolic trigger factors in melanoma pathogenesis. To substantiate this connection, we studied the expression of G-protein-coupled receptor 120 (GPR120), a receptor sensitive to unsaturated long-chain free fatty acids in melanoma tissues. One-hundred fourteen tissue sections histologically confirmed as nevi (n=32), primary melanoma (n=39), and melanoma metastasis (n=43) were immunohistochemically stained against GPR120. The staining was evaluated by three trained dermatopathologists and independently scored. Compared with nevi, primary melanoma and melanoma metastasis showed significantly higher levels of GPR120 staining. Only three out of 32 nevi showed strong GPR120 expression [median immunoreactivity-scoring system (IRS) score: 1, range: 0-10], whereas in primary melanomas 14 out of 39 were highly GPR120-positive (median IRS score: 7, range: 0-12) and in melanoma metastasis 27 out of 43 were highly GPR120-positive (median IRS score: 9, range: 0-12). GPR120 expression and tumor thickness (mm) show a statistically significant correlation in primary melanoma (P=0.011). Moreover, GPR120-positive staining was found throughout the epidermis and in sebaceous and sweat glands, which is yet not described. This study identified GPR120 as a novel marker for melanoma, indicating that melanoma cells are sensitive to free fatty acids. It is tempting to speculate that pharmacologically interfering with GPR120 signaling might improve melanoma therapy.

  5. Functional analysis of free fatty acid receptor GPR120 in human eosinophils: implications in metabolic homeostasis.

    PubMed

    Konno, Yasunori; Ueki, Shigeharu; Takeda, Masahide; Kobayashi, Yoshiki; Tamaki, Mami; Moritoki, Yuki; Oyamada, Hajime; Itoga, Masamichi; Kayaba, Hiroyuki; Omokawa, Ayumi; Hirokawa, Makoto

    2015-01-01

    Recent evidence has shown that eosinophils play an important role in metabolic homeostasis through Th2 cytokine production. GPR120 (FFA4) is a G protein-coupled receptor (GPCR) for long-chain fatty acids that functions as a regulator of physiological energy metabolism. In the present study, we aimed to investigate whether human eosinophils express GPR120 and, if present, whether it possesses a functional capacity on eosinophils. Eosinophils isolated from peripheral venous blood expressed GPR120 at both the mRNA and protein levels. Stimulation with a synthetic GPR120 agonist, GW9508, induced rapid down-regulation of cell surface expression of GPR120, suggesting ligand-dependent receptor internalization. Although GPR120 activation did not induce eosinophil chemotactic response and degranulation, we found that GW9508 inhibited eosinophil spontaneous apoptosis and Fas receptor expression. The anti-apoptotic effect was attenuated by phosphoinositide 3-kinase (PI3K) inhibitors and was associated with inhibition of caspase-3 activity. Eosinophil response investigated using ELISpot assay indicated that stimulation with a GPR120 agonist induced IL-4 secretion. These findings demonstrate the novel functional properties of fatty acid sensor GPR120 on human eosinophils and indicate the previously unrecognized link between nutrient metabolism and the immune system.

  6. Suppressive role of OGT-mediated O-GlcNAcylation of BAP1 in retinoic acid signaling.

    PubMed

    Moon, Seungtae; Lee, Yong-Kyu; Lee, Sang-Wang; Um, Soo-Jong

    2017-10-07

    BRCA1-associated protein 1 (BAP1) has been implicated in diverse biological functions, including tumor suppression. However, its regulation via glycosylation and its role in embryonic stem (ES) cells are poorly defined. BAP1 was recently reported to interact with O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT). Here, we confirmed the physical interaction and investigated its functional significance. The O-GlcNAcylation of BAP1, which requires OGT, was examined in vivo and in vitro, and was proven using alloxan, an OGT inhibitor. OGT promoted the BAP1-induced repression of retinoic acid (RA)-induced RA receptor (RAR) activation. The repressive activity of BAP1 was relieved by alloxan but exacerbated by PUGNAc, an O-GlcNAcase (OGA) inhibitor. Finally, we addressed the role of O-GlcNAcylation in the RA-induced differentiation of murine ES cells. Alkaline phosphatase staining revealed the cooperation of RA and alloxan for impairing the pluripotency of ES cells. This cooperation was also observed by measuring the size of embryonic bodies and the expression of Sox2, a pluripotency marker. Overall, our data suggest that OGT-mediated O-GlcNAcylation of BAP1 prefers the maintenance of pluripotency, whereas its inhibition facilitates RA-induced differentiation in ES cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Glucuronic acid and the ethanol metabolite ethyl-glucuronide cause Toll-like receptor 4 activation and enhanced pain

    PubMed Central

    Lewis, Susannah S.; Hutchinson, Mark R.; Zhang, Yingning; Hund, Dana K.; Maier, Steven F.; Rice, Kenner C.; Watkins, Linda R.

    2013-01-01

    We have previously observed that the non-opioid morphine metabolite, morphine-3-glucuronide, enhances pain via a toll-like receptor 4 (TLR4) dependent mechanism. The present studies were undertaken to determine whether TLR4-dependent pain enhancement generalizes to other classes of glucuronide metabolites. In silico modeling predicted that glucuronic acid alone and ethyl glucuronide, a minor but long-lasting ethanol metabolite, would dock to the same MD-2 portion of the TLR4 receptor complex previously characterized as the docking site for morphine-3-glucuronide. Glucuronic acid, ethyl glucuronide and ethanol all caused an increase in TLR4-dependent reporter protein expression in a cell line transfected with TLR4 and associated co-signaling molecules. Glucuronic acid-, ethyl glucuronide-, and ethanol-induced increases in TLR4 signaling were blocked by the TLR4 antagonists LPS-RS and (+)-naloxone. Glucuronic acid and ethyl glucuronide both caused allodynia following intrathecal injection in rats, which was blocked by intrathecal co-administration of the TLR4 antagonist LPS-RS. The finding that ethyl glucuronide can cause TLR4-dependent pain could have implications for human conditions such as hangover headache and alcohol withdrawal hyperalgesia, as well as suggesting that other classes of glucuronide metabolites could have similar effects. PMID:23348028

  8. Acidic tumor microenvironment and pH-sensing G protein-coupled receptors.

    PubMed

    Justus, Calvin R; Dong, Lixue; Yang, Li V

    2013-12-05

    The tumor microenvironment is acidic due to glycolytic cancer cell metabolism, hypoxia, and deficient blood perfusion. It is proposed that acidosis in the tumor microenvironment is an important stress factor and selection force for cancer cell somatic evolution. Acidic pH has pleiotropic effects on the proliferation, migration, invasion, metastasis, and therapeutic response of cancer cells and the function of immune cells, vascular cells, and other stromal cells. However, the molecular mechanisms by which cancer cells and stromal cells sense and respond to acidic pH in the tumor microenvironment are poorly understood. In this article the role of a family of pH-sensing G protein-coupled receptors (GPCRs) in tumor biology is reviewed. Recent studies show that the pH-sensing GPCRs, including GPR4, GPR65 (TDAG8), GPR68 (OGR1), and GPR132 (G2A), regulate cancer cell metastasis and proliferation, immune cell function, inflammation, and blood vessel formation. Activation of the proton-sensing GPCRs by acidosis transduces multiple downstream G protein signaling pathways. Since GPCRs are major drug targets, small molecule modulators of the pH-sensing GPCRs are being actively developed and evaluated. Research on the pH-sensing GPCRs will continue to provide important insights into the molecular interaction between tumor and its acidic microenvironment and may identify new targets for cancer therapy and chemoprevention.

  9. Kynurenic acid as an Antagonist of α7 Nicotinic Acetylcholine Receptors in the Brain: Facts and Challenges

    PubMed Central

    Albuquerque, Edson X.; Schwarcz, Robert

    2013-01-01

    Kynurenic acid (KYNA), a major tryptophan metabolite, is a glutamate receptor antagonist, which is also reported to inhibit α7 nicotinic acetylcholine receptors (α7nAChRs). Due to variations in experimental approaches, controversy has arisen regarding the ability of KYNA to directly influence α7nAChR function. Here we summarize current concepts of KYNA neurobiology and review evidence pertaining to the proposed role of KYNA as an endogenous modulator of α7nAChRs and synaptic transmission. As dysfunction of α7nAChRs plays a major role in the pathophysiology of central nervous system disorders, elucidation of KYNA's action on this receptor subtype has significant therapeutic implications. PMID:23270993

  10. Inhibition of epidermal growth factor receptor by ferulic acid and 4-vinylguaiacol in human breast cancer cells.

    PubMed

    Sudhagar, S; Sathya, S; Anuradha, R; Gokulapriya, G; Geetharani, Y; Lakshmi, B S

    2018-02-01

    To examine the potential of ferulic acid and 4-vinylguaiacol for inhibiting epidermal growth factor receptor (EGFR) in human breast cancer cells in vitro. Ferulic acid and 4-vinylguaiacol limit the EGF (epidermal growth factor)-induced breast cancer proliferation and new DNA synthesis. Western blot analysis revealed both ferulic acid and 4-vinylguaiacol exhibit sustained inhibition of EGFR activation through down-regulation of Tyr 1068 autophosphorylation. Molecular docking analysis shows ferulic acid forming hydrogen bond interaction with Lys 745 and Met 793 whereas, 4-vinylguaiacol forms two hydrogen bonds with Phe 856 and exhibits stronger hydrophobic interactions with multiple amino acid residues at the EGFR kinase domain. Ferulic acid and 4-vinylguaiacol could serve as a potential structure for the development of new small molecule therapeutics against EGFR.

  11. Anti-Inflammatory and Insulin-Sensitizing Effects of Free Fatty Acid Receptors.

    PubMed

    Miyamoto, Junki; Kasubuchi, Mayu; Nakajima, Akira; Kimura, Ikuo

    2017-01-01

    Chronic low-grade inflammation in macrophages and adipose tissues can promote the development of obesity and type 2 diabetes. Free fatty acids (FFAs) have important roles in various tissues, acting as both essential energy sources and signaling molecules. FFA receptors (FFARs) can modulate inflammation in various types of cells and tissues; however the underlying mechanisms mediating these effects are unclear. FFARs are activated by specific FFAs; for example, GPR40 and GPR120 are activated by medium and long chain FFAs, GPR41 and GPR43 are activated by short chain FFAs, and GPR84 is activated by medium-chain FFAs. To date, a number of studies associated with the physiological functions of G protein-coupled receptors (GPCRs) have reported that these GPCRs are expressed in various tissues and involved in inflammatory and metabolic responses. Thus, the development of selective agonists or antagonists for various GPCRs may facilitate the establishment of novel therapies for the treatment of various diseases. In this review, we summarize current literature describing the potential of GPCRs as therapeutic targets for inflammatory and metabolic disorders.

  12. Amino acid residues in the GerAB protein important in the function and assembly of the alanine spore germination receptor of Bacillus subtilis 168.

    PubMed

    Cooper, Gareth R; Moir, Anne

    2011-05-01

    The paradigm gerA operon is required for endospore germination in response to c-alanine as the sole germinant, and the three protein products, GerAA, GerAB, and GerAC are predicted to form a receptor complex in the spore inner membrane. GerAB shows homology to the amino acid-polyamine-organocation (APC) family of single-component transporters and is predicted to be an integral membrane protein with 10 membrane-spanning helices. Site-directed mutations were introduced into the gerAB gene at its natural location on the chromosome. Alterations to some charged or potential helix-breaking residues within membrane spans affected receptor function dramatically. In some cases, this is likely to reflect the complete loss of the GerA receptor complex, as judged by the absence of the germinant receptor protein GerAC, which suggests that the altered GerAB protein itself may be unstable or that the altered structure destabilizes the complex. Mutants that have a null phenotype for Instituto de Biotecnología de León, INBIOTEC, Parque Científico de León, Av. Real, 1, 24006 León, Spain-alanine germination but retain GerAC protein at near-normal levels are more likely to define amino acid residues of functional, rather than structural, importance. Single-amino-acid substitutions in each of the GerAB and GerAA proteins can prevent incorporation of GerAC protein into the spore; this provides strong evidence that the proteins within a specific receptor interact and that these interactions are required for receptor assembly. The lipoprotein nature of the GerAC receptor subunit is also important; an amino acid change in the prelipoprotein signal sequence in the gerAC1 mutant results in the absence of GerAC protein from the spore.

  13. Regulation of B cell functions by the sialic acid-binding receptors siglec-G and CD22.

    PubMed

    Jellusova, Julia; Nitschke, Lars

    2011-01-01

    B cell antigen receptor (BCR) engagement can lead to many different physiologic outcomes. To achieve an appropriate response, the BCR signal is interpreted in the context of other stimuli and several additional receptors on the B cell surface participate in the modulation of the signal. Two members of the Siglec (sialic acid-binding immunoglobulin-like lectin) family, CD22 and Siglec-G have been shown to inhibit the BCR signal. Recent findings indicate that the ability of these two receptors to bind sialic acids might be important to induce tolerance to self-antigens. Sialylated glycans are usually absent on microbes but abundant in higher vertebrates and might therefore provide an important tolerogenic signal. Since the expression of the specific ligands for Siglec-G and CD22 is tightly regulated and since Siglecs are not only able to bind their ligands in trans but also on the same cell surface this might provide additional mechanisms to control the BCR signal. Although both Siglec-G and CD22 are expressed on B cells and are able to inhibit BCR mediated signaling, they also show unique biological functions. While CD22 is the dominant regulator of calcium signaling on conventional B2 cells and also seems to play a role on marginal zone B cells, Siglec-G exerts its function mainly on B1 cells and influences their lifespan and antibody production. Both Siglec-G and CD22 have also recently been linked to toll-like receptor signaling and may provide a link in the regulation of the adaptive and innate immune response of B cells.

  14. Stereocontrolled dopamine receptor binding and subtype selectivity of clebopride analogues synthesized from aspartic acid.

    PubMed

    Einsiedel, Jürgen; Weber, Klaus; Thomas, Christoph; Lehmann, Thomas; Hübner, Harald; Gmeiner, Peter

    2003-10-06

    Employing the achiral 4-aminopiperidine derivative clebopride as a lead compound, chiral analogues were developed displaying dopamine receptor binding profiles that proved to be strongly dependent on the stereochemistry. Compared to the D1 receptor, the test compounds showed high selectivity for the D2-like subtypes including D2(long), D2(short), D3 and D4. The highest D4 and D3 affinities were observed for the cis-3-amino-4-methylpyrrolidines 3e and the enantiomer ent3e resulting in K(i) values of 0.23 and 1.8 nM, respectively. The benzamides of type 3 and 5 were synthesized in enantiopure form starting from (S)-aspartic acid and its unnatural optical antipode.

  15. Phytohormone abscisic acid elicits antinociceptive effects in rats through the activation of opioid and peroxisome proliferator-activated receptors β/δ.

    PubMed

    Mollashahi, Mahtab; Abbasnejad, Mehdi; Esmaeili-Mahani, Saeed

    2018-08-05

    The phytohormone abscisic acid exists in animal tissues particularly in the brain. However, its neurophysiological effects have not yet been fully clarified. This study was designed to evaluate the possible antinociceptive effects of abscisic acid on animal models of pain and determine its possible signaling mechanism. Tail-flick, hot-plate and formalin tests were used to assess the nociceptive threshold. All experiments were carried out on male Wistar rats. To determine the role of Peroxisome proliferator-activated receptor β/δ (PPARβ/δ) and opioid receptors on the induction of abscisic acid antinociception, specific antagonists were injected 15 min before abscisic acid. The data showed that abscisic acid (5, 10 and 15 µg/rat, i.c.v.) significantly decreased pain responses in formalin test. In addition, it could also produce dose-dependent antinociceptive effect in tail-flick and hot-plate tests. Administration of PPARβ/δ antagonist (GSK0660, 80 nM, i.c.v.) significantly attenuated the antinociceptive effect of abscisic acid in all tests. The antinociceptive effects of abscisic acid were completely inhibited by naloxone (6 µg, i.c.v.) during the time course of tail-flick and hot-plate tests. The results indicated that the central injection of abscisic acid has potent pain-relieving property which is mediated partly via the PPAR β/δ and opioid signaling. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Free fatty acid receptors and their role in regulation of energy metabolism.

    PubMed

    Hara, Takafumi; Kimura, Ikuo; Inoue, Daisuke; Ichimura, Atsuhiko; Hirasawa, Akira

    2013-01-01

    The free fatty acid receptor (FFAR) is a G protein-coupled receptor (GPCR) activated by free fatty acids (FFAs), which play important roles not only as essential nutritional components but also as signaling molecules in numerous physiological processes. In the last decade, FFARs have been identified by the GPCR deorphanization strategy derived from the human genome database. To date, several FFARs have been identified and characterized as critical components in various physiological processes. FFARs are categorized according to the chain length of FFA ligands that activate each FFAR; FFA2 and FFA3 are activated by short chain FFAs, GPR84 is activated by medium-chain FFAs, whereas FFA1 and GPR120 are activated by medium- or long-chain FFAs. FFARs appear to act as physiological sensors for food-derived FFAs and digestion products in the gastrointestinal tract. Moreover, they are considered to be involved in the regulation of energy metabolism mediated by the secretion of insulin and incretin hormones and by the regulation of the sympathetic nerve systems, taste preferences, and inflammatory responses related to insulin resistance. Therefore, because FFARs can be considered to play important roles in physiological processes and various pathophysiological processes, FFARs have been targeted in therapeutic strategies for the treatment of metabolic disorders including type 2 diabetes and metabolic syndrome. In this review, we present a summary of recent progress regarding the understanding of their physiological roles in the regulation of energy metabolism and their potential as therapeutic targets.

  17. Mining microarray datasets in nutrition: expression of the GPR120 (n-3 fatty acid receptor/sensor) gene is down-regulated in human adipocytes by macrophage secretions.

    PubMed

    Trayhurn, Paul; Denyer, Gareth

    2012-01-01

    Microarray datasets are a rich source of information in nutritional investigation. Targeted mining of microarray data following initial, non-biased bioinformatic analysis can provide key insight into specific genes and metabolic processes of interest. Microarrays from human adipocytes were examined to explore the effects of macrophage secretions on the expression of the G-protein-coupled receptor (GPR) genes that encode fatty acid receptors/sensors. Exposure of the adipocytes to macrophage-conditioned medium for 4 or 24 h had no effect on GPR40 and GPR43 expression, but there was a marked stimulation of GPR84 expression (receptor for medium-chain fatty acids), the mRNA level increasing 13·5-fold at 24 h relative to unconditioned medium. Importantly, expression of GPR120, which encodes an n-3 PUFA receptor/sensor, was strongly inhibited by the conditioned medium (15-fold decrease in mRNA at 24 h). Macrophage secretions have major effects on the expression of fatty acid receptor/sensor genes in human adipocytes, which may lead to an augmentation of the inflammatory response in adipose tissue in obesity.

  18. Fatty acids and hypolipidemic drugs regulate peroxisome proliferator-activated receptors alpha - and gamma-mediated gene expression via liver fatty acid binding protein: a signaling path to the nucleus.

    PubMed

    Wolfrum, C; Borrmann, C M; Borchers, T; Spener, F

    2001-02-27

    Peroxisome proliferator-activated receptor alpha (PPARalpha) is a key regulator of lipid homeostasis in hepatocytes and target for fatty acids and hypolipidemic drugs. How these signaling molecules reach the nuclear receptor is not known; however, similarities in ligand specificity suggest the liver fatty acid binding protein (L-FABP) as a possible candidate. In localization studies using laser-scanning microscopy, we show that L-FABP and PPARalpha colocalize in the nucleus of mouse primary hepatocytes. Furthermore, we demonstrate by pull-down assay and immunocoprecipitation that L-FABP interacts directly with PPARalpha. In a cell biological approach with the aid of a mammalian two-hybrid system, we provide evidence that L-FABP interacts with PPARalpha and PPARgamma but not with PPARbeta and retinoid X receptor-alpha by protein-protein contacts. In addition, we demonstrate that the observed interaction of both proteins is independent of ligand binding. Final and quantitative proof for L-FABP mediation was obtained in transactivation assays upon incubation of transiently and stably transfected HepG2 cells with saturated, monounsaturated, and polyunsaturated fatty acids as well as with hypolipidemic drugs. With all ligands applied, we observed strict correlation of PPARalpha and PPARgamma transactivation with intracellular concentrations of L-FABP. This correlation constitutes a nucleus-directed signaling by fatty acids and hypolipidemic drugs where L-FABP acts as a cytosolic gateway for these PPARalpha and PPARgamma agonists. Thus, L-FABP and the respective PPARs could serve as targets for nutrients and drugs to affect expression of PPAR-sensitive genes.

  19. Chimeric NDP-MSH and MTII melanocortin peptides with agouti-related protein (AGRP) Arg-Phe-Phe amino acids possess agonist melanocortin receptor activity.

    PubMed

    Joseph, Christine G; Wilczynski, Andrzej; Holder, Jerry R; Xiang, Zhimin; Bauzo, Rayna M; Scott, Joseph W; Haskell-Luevano, Carrie

    2003-12-01

    Agouti-related protein (AGRP) is one of only two known endogenous antagonists of G-protein coupled receptors (GPCRs). Specifically, AGRP antagonizes the brain melanocortin-3 and -4 receptors involved in energy homeostasis, regulation of feeding behavior, and obesity. Alpha-melanocyte stimulating hormone (alpha-MSH) is one of the known endogenous agonists for these receptors. It has been hypothesized that the Arg-Phe-Phe (111-113) human AGRP amino acids may be mimicking the melanocortin agonist Phe-Arg-Trp (7-9) residue interactions with the melanocortin receptors that are important for both receptor molecular recognition and stimulation. To test this hypothesis, we generated thirteen chimeric peptide ligands based upon the melanocortin agonist peptides NDP-MSH (Ac-Ser-Tyr-Ser-Nle4-Glu-His-DPhe-Arg-Trp-Gly-Lys-Pro-Val-NH2) and MTII (Ac-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-NH2). In these chimeric ligands, the agonist DPhe-Arg-Trp amino acids were replaced by the AGRP Arg-Phe-Phe residues, and resulted in agonist activity at the mouse melanocortin receptors (mMC1R and mMC3-5Rs), supporting the hypothesis that the AGRP antagonist ligand Arg-Phe-Phe residues mimic the agonist Phe-Arg-Trp amino acids. Interestingly, the Ac-Ser-Tyr-Ser-Nle4-Glu-His-Arg-DPhe-Phe-Gly-Lys-Pro-Val-NH2 peptide possessed 7 nM mMC1R agonist potency, and is 850-fold selective for the mMC1R versus the mMC3R, 2300-fold selective for the mMC1R versus the mMC4R, and 60-fold selective for the MC1R versus the mMC5R, resulting in the discovery of a new peptide template for the design of melanocortin receptor selective ligands.

  20. Food deprivation modulates gamma-aminobutyric acid receptors and peripheral benzodiazepine binding sites in rats.

    PubMed

    Weizman, A; Bidder, M; Fares, F; Gavish, M

    1990-12-03

    The effect of 5 days of food deprivation followed by 5 days of refeeding on gamma-aminobutyric acid (GABA) receptors, central benzodiazepine receptors (CBR), and peripheral benzodiazepine binding sites (PBzS) was studied in female Sprague-Dawley rats. Starvation induced a decrease in the density of PBzS in peripheral organs: adrenal (35%; P less than 0.001), kidney (33%; P less than 0.01), and heart (34%; P less than 0.001). Restoration of [3H]PK 11195 binding to normal values was observed in all three organs after 5 days of refeeding. The density of PBzS in the ovary, pituitary, and hypothalamus was not affected by starvation. Food deprivation resulted in a 35% decrease in cerebellar GABA receptors (P less than 0.01), while CBR in the hypothalamus and cerebral cortex remained unaltered. The changes in PBzS observed in the heart and kidney may be related to the long-term metabolic stress associated with starvation and to the functional changes occurring in these organs. The down-regulation of the adrenal PBzS is attributable to the suppressive effect of hypercortisolemia on pituitary ACTH release. The reduction in cerebellar GABA receptors may be an adaptive response to food deprivation stress and may be relevant to the proaggressive effect of hunger.

  1. Mutagenesis Analysis Reveals Distinct Amino Acids of the Human Serotonin 5-HT2C Receptor Underlying the Pharmacology of Distinct Ligands.

    PubMed

    Liu, Yue; Canal, Clinton E; Cordova-Sintjago, Tania C; Zhu, Wanying; Booth, Raymond G

    2017-01-18

    While exploring the structure-activity relationship of 4-phenyl-2-dimethylaminotetralins (PATs) at serotonin 5-HT 2C receptors, we discovered that relatively minor modification of PAT chemistry impacts function at 5-HT 2C receptors. In HEK293 cells expressing human 5-HT 2C-INI receptors, for example, (-)-trans-3'-Br-PAT and (-)-trans-3'-Cl-PAT are agonists regarding Gα q -inositol phosphate signaling, whereas (-)-trans-3'-CF 3 -PAT is an inverse agonist. To investigate the ligand-receptor interactions that govern this change in function, we performed site-directed mutagenesis of 14 amino acids of the 5-HT 2C receptor based on molecular modeling and reported G protein-coupled receptor crystal structures, followed by molecular pharmacology studies. We found that S3.36, T3.37, and F5.47 in the orthosteric binding pocket are critical for affinity (K i ) of all PATs tested, we also found that F6.44, M6.47, C7.45, and S7.46 are primarily involved in regulating EC/IC 50 functional potencies of PATs. We discovered that when residue S5.43, N6.55, or both are mutated to alanine, (-)-trans-3'-CF 3 -PAT switches from inverse agonist to agonist function, and when N6.55 is mutated to leucine, (-)-trans-3'-Br-PAT switches from agonist to inverse agonist function. Notably, most point-mutations that affected PAT pharmacology did not significantly alter affinity (K D ) of the antagonist radioligand [ 3 H]mesulergine, but every mutation tested negatively impacted serotonin binding. Also, amino acid mutations differentially affected the pharmacology of other commercially available 5-HT 2C ligands tested. Collectively, the data show that functional outcomes shared by different ligands are mediated by different amino acids and that some 5-HT 2C receptor residues important for pharmacology of one ligand are not necessarily important for another ligand.

  2. Bile acids override steatosis in farnesoid X receptor deficient mice in a model of non-alcoholic steatohepatitis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, Weibin; Liu, Xijun; Peng, Xiaomin

    Highlights: • FXR deficiency enhanced MCD diet-induced hepatic fibrosis. • FXR deficiency attenuated MCD diet-induced hepatic steatosis. • FXR deficiency repressed genes involved in fatty acid uptake and triglyceride accumulation. - Abstract: Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases, and the pathogenesis is still not well known. The farnesoid X receptor (FXR) is a member of the nuclear hormone receptor superfamily and plays an essential role in maintaining bile acid and lipid homeostasis. In this study, we study the role of FXR in the pathogenesis of NFALD. We found that FXR deficient (FXR{sup −/−})more » mice fed methionine- and choline-deficient (MCD) diet had higher serum ALT and AST activities and lower hepatic triglyceride levels than wild-type (WT) mice fed MCD diet. Expression of genes involved in inflammation (VCAM-1) and fibrosis (α-SMA) was increased in FXR{sup −/−} mice fed MCD diet (FXR{sup −/−}/MCD) compared to WT mice fed MCD diet (WT/MCD). Although MCD diet significantly induced hepatic fibrosis in terms of liver histology, FXR{sup −/−}/MCD mice showed less degree of hepatic steatosis than WT/MCD mice. Moreover, FXR deficiency synergistically potentiated the elevation effects of MCD diet on serum and hepatic bile acids levels. The super-physiological concentrations of hepatic bile acids in FXR{sup −/−}/MCD mice inhibited the expression of genes involved in fatty acid uptake and triglyceride accumulation, which may be an explanation for less steatosis in FXR{sup −/−}/MCD mice in contrast to WT/MCD mice. These results suggest that hepatic bile acids accumulation could override simple steatosis in hepatic injury during the progression of NAFLD and further emphasize the role of FXR in maintaining hepatic bile acid homeostasis in liver disorders and in hepatic protection.« less

  3. Isoflavones enhance interleukin-17 gene expression via retinoic acid receptor-related orphan receptors α and γ

    PubMed Central

    Kojima, Hiroyuki; Takeda, Yukimasa; Muromoto, Ryuta; Takahashi, Miki; Hirao, Toru; Takeuchi, Shinji; Jetten, Anton M.; Matsuda, Tadashi

    2018-01-01

    The retinoic acid receptor-related orphan receptors α and γ (RORα and RORγ), are key regulators of helper T (Th)17 cell differentiation, which is involved in the innate immune system and autoimmune disorders. In this study, we investigated the effects of isoflavones on RORα/γ activity and the gene expression of interleukin (IL)-17, which mediates the function of Th17 cells. In doxycycline-inducible CHO stable cell lines, we found that four isoflavones, biochanin A (BA), genistein, formononetin, and daidzein, enhanced RORα- or RORγ-mediated transcriptional activity in a dose-dependent manner. In an activation assay of the Il17a promoter using Jurkat cells, these compounds enhanced the RORα- or RORγ-mediated activation of the Il17a promoter at concentrations of 1 × 10−6 M to 1 × 10−5 M. In mammalian two-hybrid assays, the four isoflavones enhanced the interaction between the RORα- or RORγ-ligand binding domain and the co-activator LXXLL peptide in a dose-dependent manner. In addition, these isoflavones potently enhanced Il17a mRNA expression in mouse T lymphoma EL4 cells treated with phorbol myristate acetate and ionomycin, but showed slight enhancement of Il17a gene expression in RORα/γ-knockdown EL4 cells. Immunoprecipitation and immunoblotting assays also revealed that BA enhanced the interaction between RORγt and SRC-1, which is a co-activator for nuclear receptors. Taken together, these results suggest that the isoflavones have the ability to enhance IL-17 gene expression by stabilizing the interactions between RORα/γ and co-activators. This also provides the first evidence that dietary chemicals can enhance IL-17 gene expression in immune cells. PMID:25583575

  4. Ursodeoxycholic acid exerts farnesoid X receptor-antagonistic effects on bile acid and lipid metabolism in morbid obesity.

    PubMed

    Mueller, Michaela; Thorell, Anders; Claudel, Thierry; Jha, Pooja; Koefeler, Harald; Lackner, Carolin; Hoesel, Bastian; Fauler, Guenter; Stojakovic, Tatjana; Einarsson, Curt; Marschall, Hanns-Ulrich; Trauner, Michael

    2015-06-01

    Bile acids (BAs) are major regulators of hepatic BA and lipid metabolism but their mechanisms of action in non-alcoholic fatty liver disease (NAFLD) are still poorly understood. Here we aimed to explore the molecular and biochemical mechanisms of ursodeoxycholic acid (UDCA) in modulating the cross-talk between liver and visceral white adipose tissue (vWAT) regarding BA and cholesterol metabolism and fatty acid/lipid partitioning in morbidly obese NAFLD patients. In this randomized controlled pharmacodynamic study, we analyzed serum, liver and vWAT samples from 40 well-matched morbidly obese patients receiving UDCA (20 mg/kg/day) or no treatment three weeks prior to bariatric surgery. Short term UDCA administration stimulated BA synthesis by reducing circulating fibroblast growth factor 19 and farnesoid X receptor (FXR) activation, resulting in cholesterol 7α-hydroxylase induction mirrored by elevated C4 and 7α-hydroxycholesterol. Enhanced BA formation depleted hepatic and LDL-cholesterol with subsequent activation of the key enzyme of cholesterol synthesis 3-hydroxy-3-methylglutaryl-CoA reductase. Blunted FXR anti-lipogenic effects induced lipogenic stearoyl-CoA desaturase (SCD) in the liver, thereby increasing hepatic triglyceride content. In addition, induced SCD activity in vWAT shifted vWAT lipid metabolism towards generation of less toxic and more lipogenic monounsaturated fatty acids such as oleic acid. These data demonstrate that by exerting FXR-antagonistic effects, UDCA treatment in NAFLD patients strongly impacts on cholesterol and BA synthesis and induces neutral lipid accumulation in both liver and vWAT. Copyright © 2015 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

  5. Regulation of B Cell Functions by the Sialic Acid-Binding Receptors Siglec-G and CD22

    PubMed Central

    Jellusova, Julia; Nitschke, Lars

    2011-01-01

    B cell antigen receptor (BCR) engagement can lead to many different physiologic outcomes. To achieve an appropriate response, the BCR signal is interpreted in the context of other stimuli and several additional receptors on the B cell surface participate in the modulation of the signal. Two members of the Siglec (sialic acid-binding immunoglobulin-like lectin) family, CD22 and Siglec-G have been shown to inhibit the BCR signal. Recent findings indicate that the ability of these two receptors to bind sialic acids might be important to induce tolerance to self-antigens. Sialylated glycans are usually absent on microbes but abundant in higher vertebrates and might therefore provide an important tolerogenic signal. Since the expression of the specific ligands for Siglec-G and CD22 is tightly regulated and since Siglecs are not only able to bind their ligands in trans but also on the same cell surface this might provide additional mechanisms to control the BCR signal. Although both Siglec-G and CD22 are expressed on B cells and are able to inhibit BCR mediated signaling, they also show unique biological functions. While CD22 is the dominant regulator of calcium signaling on conventional B2 cells and also seems to play a role on marginal zone B cells, Siglec-G exerts its function mainly on B1 cells and influences their lifespan and antibody production. Both Siglec-G and CD22 have also recently been linked to toll-like receptor signaling and may provide a link in the regulation of the adaptive and innate immune response of B cells. PMID:22566885

  6. Orphan nuclear receptor oestrogen-related receptor γ (ERRγ) plays a key role in hepatic cannabinoid receptor type 1-mediated induction of CYP7A1 gene expression

    PubMed Central

    Zhang, Yaochen; Kim, Don-Kyu; Lee, Ji-Min; Park, Seung Bum; Jeong, Won-IL; Kim, Seong Heon; Lee, In-Kyu; Lee, Chul-Ho; Chiang, John Y.L.; Choi, Hueng-Sik

    2017-01-01

    Bile acids are primarily synthesized from cholesterol in the liver and have important roles in dietary lipid absorption and cholesterol homoeostasis. Detailed roles of the orphan nuclear receptors regulating cholesterol 7α-hydroxylase (CYP7A1), the rate-limiting enzyme in bile acid synthesis, have not yet been fully elucidated. In the present study, we report that oestrogen-related receptor γ (ERRγ) is a novel transcriptional regulator of CYP7A1 expression. Activation of cannabinoid receptor type 1 (CB1 receptor) signalling induced ERRγ-mediated transcription of the CYP7A1 gene. Overexpression of ERRγ increased CYP7A1 expression in vitro and in vivo, whereas knockdown of ERRγ attenuated CYP7A1 expression. Deletion analysis of the CYP7A1 gene promoter and a ChIP assay revealed an ERRγ -binding site on the CYP7A1 gene promoter. Small heterodimer partner (SHP) inhibited the transcriptional activity of ERRγ and thus regulated CYP7A1 expression. Overexpression of ERRγ led to increased bile acid levels, whereas an inverse agonist of ERRγ, GSK5182, reduced CYP7A1 expression and bile acid synthesis. Finally, GSK5182 significantly reduced hepatic CB1 receptor-mediated induction of CYP7A1 expression and bile acid synthesis in alcohol-treated mice. These results provide the molecular mechanism linking ERRγ and bile acid metabolism. PMID:26348907

  7. Lysergic acid diethylamide-induced Fos expression in rat brain: role of serotonin-2A receptors.

    PubMed

    Gresch, P J; Strickland, L V; Sanders-Bush, E

    2002-01-01

    Lysergic acid diethylamide (LSD) produces altered mood and hallucinations in humans and binds with high affinity to serotonin-2A (5-HT(2A)) receptors. Although LSD interacts with other receptors, the activation of 5-HT(2A) receptors is thought to mediate the hallucinogenic properties of LSD. The goal of this study was to identify the brain sites activated by LSD and to determine the influence of 5-HT(2A) receptors in this activation. Rats were pretreated with the 5-HT(2A) receptor antagonist MDL 100907 (0.3 mg/kg, i.p.) or vehicle 30 min prior to LSD (500 microg/kg, i.p.) administration and killed 3 h later. Brain tissue was examined for Fos protein expression by immunohistochemistry. LSD administration produced a five- to eight-fold increase in Fos-like immunoreactivity in medial prefrontal cortex, anterior cingulate cortex, and central nucleus of amygdala. However, in dorsal striatum and nucleus accumbens no increase in Fos-like immunoreactivity was observed. Pretreatment with MDL 100907 completely blocked LSD-induced Fos-like immunoreactivity in medial prefrontal cortex and anterior cingulate cortex, but only partially blocked LSD-induced Fos-like immunoreactivity in amygdala. Double-labeled immunohistochemistry revealed that LSD did not induce Fos-like immunoreactivity in cortical cells expressing 5-HT(2A) receptors, suggesting an indirect activation of cortical neurons. These results indicate that the LSD activation of medial prefrontal cortex and anterior cingulate cortex is mediated by 5-HT(2A) receptors, whereas in amygdala 5-HT(2A) receptor activation is a component of the response. These findings support the hypothesis that the medial prefrontal cortex, anterior cingulate cortex, and perhaps the amygdala, are important regions involved in the production of hallucinations. Copyright 2002 IBRO

  8. NR4A orphan nuclear receptors influence retinoic acid and docosahexaenoic acid signaling via up-regulation of fatty acid binding protein 5

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Volakakis, Nikolaos; Joodmardi, Eliza; Perlmann, Thomas, E-mail: thomas.perlmann@licr.ki.se

    2009-12-25

    The orphan nuclear receptor (NR) Nurr1 is expressed in the developing and adult nervous system and is also induced as an immediate early gene in a variety of cell types. In silico analysis of human promoters identified fatty acid binding protein 5 (FABP5), a protein shown to enhance retinoic acid-mediated PPAR{beta}/{delta} signaling, as a potential Nurr1 target gene. Nurr1 has previously been implicated in retinoid signaling via its heterodimerization partner RXR. Since NRs are commonly involved in cross-regulatory control we decided to further investigate the regulatory relationship between Nurr1 and FABP5. FABP5 expression was up-regulated by Nurr1 and other NR4Amore » NRs in HEK293 cells, and Nurr1 was shown to activate and bind to the FABP5 promoter, supporting that FABP5 is a direct downstream target of NR4A NRs. We also show that the RXR ligand docosahexaenoic acid (DHA) can induce nuclear translocation of FABP5. Moreover, via up-regulation of FABP5 Nurr1 can enhance retinoic acid-induced signaling of PPAR{beta}/{delta} and DHA-induced activation of RXR. We also found that other members of the NR4A orphan NRs can up-regulate FABP5. Thus, our findings suggest that NR4A orphan NRs can influence signaling events of other NRs via control of FABP5 expression levels.« less

  9. Different expressions and DNA methylation patterns of lysophosphatidic acid receptor genes in mouse tumor cells.

    PubMed

    Okabe, Kyoko; Hayashi, Mai; Wakabayashi, Naoko; Yamawaki, Yasuna; Teranishi, Miki; Fukushima, Nobuyuki; Tsujiuchi, Toshifumi

    2010-01-01

    Lysophosphatidic acid (LPA) receptors act as several biological effectors through LPA, which is a bioactive phospholipid. Recently, aberrant expressions of LPA receptor genes due to DNA methylation have been detected in several tumor cells. In this study, we measured expression levels and DNA methylation status of LPA receptor genes in mouse tumor cells, LL/2 lung carcinoma, B16F0 melanoma, FM3A mammary carcinoma and L1210 leukemia cells, compared with normal tissues. Total RNAs were extracted and RT-PCR analysis was performed. For DNA methylation status, bisulfite sequencing analysis was carried out, comparing outcomes with other tumor cells and normal tissues. The expressions of LPA1 gene were shown in LL/2, but not in B16F0, FM3A and L1210 cells. While the LPA2 gene was expressed in all 4 tumor cells, the LPA3 gene was unexpressed in them. The LPA1 and LPA3 unexpressed cells were highly methylated, although normal tissues were all unmethylated. The DNA methylation status was correlated with gene expression levels in cancer cells. The present results demonstrate that DNA methylation patterns of LPA receptor genes are dependent on cancer cell types, suggesting that LPA receptors may be new molecular targets for therapeutic approaches and chemoprevention. Copyright © 2011 S. Karger AG, Basel.

  10. Activation of RAS/ERK alone is insufficient to inhibit RXRα function and deplete retinoic acid in hepatocytes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Ai-Guo, E-mail: wangaiguotl@hotmail.com; Song, Ya-Nan; Chen, Jun

    2014-09-26

    Highlights: • The activation of RAS/ERK is insufficient to inhibit RXRα function and deplete RA. • The retinoid metabolism-related genes are down-regulated by ras oncogene. • The atRA has no effect on preventing hepatic tumorigenesis or curing the developed hepatic nodules. - Abstract: Activation of RAS/ERK signaling pathway, depletion of retinoid, and phosphorylation of retinoid X receptor alpha (RXRα) are frequent events found in liver tumors and thought to play important roles in hepatic tumorigenesis. However, the relationships among them still remained to be elucidated. By exploring the transgenic mouse model of hepatic tumorigenesis induced by liver-specific expression of H-ras12Vmore » oncogene, the activation of RAS/ERK, the mRNA expression levels of retinoid metabolism-related genes, the contents of retinoid metabolites, and phosphorylation of RXRα were determined. RAS/ERK signaling pathway was gradually and significantly activated in hepatic tumor adjacent normal liver tissues (P) and hepatic tumor tissues (T) of H-ras12V transgenic mice compared with normal liver tissues (Wt) of wild type mice. On the contrary, the mRNA expression levels of retinoid metabolism-related genes were significantly reduced in P and T compared with Wt. Interestingly, the retinoid metabolites 9-cis-retinoic acid (9cRA) and all-trans-retinoic acid (atRA), the well known ligands for nuclear transcription factor RXR and retinoic acid receptor (RAR), were significantly decreased only in T compared with Wt and P, although the oxidized polar metabolite of atRA, 4-keto-all-trans-retinoic-acid (4-keto-RA) was significantly decreased in both P and T compared with Wt. To our surprise, the functions of RXRα were significantly blocked only in T compared with Wt and P. Namely, the total protein levels of RXRα were significantly reduced and the phosphorylation levels of RXRα were significantly increased only in T compared with Wt and P. Treatment of H-ras12V transgenic mice at 5

  11. Dysregulated endocardial TGFβ signaling and mesenchymal transformation result in heart outflow tract septation failure.

    PubMed

    Ma, Mancheong; Li, Peng; Shen, Hua; Estrada, Kristine D; Xu, Jian; Kumar, S Ram; Sucov, Henry M

    2016-01-01

    Heart outflow tract septation in mouse embryos carrying mutations in retinoic acid receptor genes fails with complete penetrance. In this mutant background, ectopic TGFβ signaling in the distal outflow tract is responsible for septation failure, but it was uncertain what tissue was responsive to ectopic TGFβ and why this response interfered with septation. By combining RAR gene mutation with tissue-specific Cre drivers and a conditional type II TGFβ receptor (Tgfbr2) allele, we determined that ectopic activation of TGFβ signaling in the endocardium is responsible for septation defects. Ectopic TGFβ signaling results in ectopic mesenchymal transformation of the endocardium and thereby in improperly constituted distal OFT cushions. Our analysis highlights the interactions between myocardium, endocardium, and neural crest cells in outflow tract morphogenesis, and demonstrates the requirement for proper TGFβ signaling in outflow tract cushion organization and septation. Copyright © 2015. Published by Elsevier Inc.

  12. Mining microarray datasets in nutrition: expression of the GPR120 (n-3 fatty acid receptor/sensor) gene is down-regulated in human adipocytes by macrophage secretions

    PubMed Central

    Trayhurn, Paul; Denyer, Gareth

    2012-01-01

    Microarray datasets are a rich source of information in nutritional investigation. Targeted mining of microarray data following initial, non-biased bioinformatic analysis can provide key insight into specific genes and metabolic processes of interest. Microarrays from human adipocytes were examined to explore the effects of macrophage secretions on the expression of the G-protein-coupled receptor (GPR) genes that encode fatty acid receptors/sensors. Exposure of the adipocytes to macrophage-conditioned medium for 4 or 24 h had no effect on GPR40 and GPR43 expression, but there was a marked stimulation of GPR84 expression (receptor for medium-chain fatty acids), the mRNA level increasing 13·5-fold at 24 h relative to unconditioned medium. Importantly, expression of GPR120, which encodes an n-3 PUFA receptor/sensor, was strongly inhibited by the conditioned medium (15-fold decrease in mRNA at 24 h). Macrophage secretions have major effects on the expression of fatty acid receptor/sensor genes in human adipocytes, which may lead to an augmentation of the inflammatory response in adipose tissue in obesity. PMID:25191551

  13. Modulation of fear memory by dietary polyunsaturated fatty acids via cannabinoid receptors.

    PubMed

    Yamada, Daisuke; Takeo, Jiro; Koppensteiner, Peter; Wada, Keiji; Sekiguchi, Masayuki

    2014-07-01

    Although the underlying mechanism remains unknown, several studies have suggested benefits of n-3 long-chain polyunsaturated fatty acid (PUFA) for patients with anxiety disorders. Elevated fear is thought to contribute to the pathogenesis of particular anxiety disorders. The aim of the present study was to evaluate whether the dietary n-3 to n-6 PUFA (3:6) ratio influences fear memory. For this purpose, the effects of various dietary 3:6 ratios on fear memory were examined in mice using contextual fear conditioning, and the effects of these diets on central synaptic transmission were examined to elucidate the mechanism of action of PUFA. We found that fear memory correlated negatively with dietary, serum, and brain 3:6 ratios in mice. The low fear memory in mice fed a high 3:6 ratio diet was increased by the cannabinoid CB1 receptor antagonist rimonabant, reaching a level seen in mice fed a low 3:6 ratio diet. The agonist sensitivity of CB1 receptor was enhanced in the basolateral nucleus of the amygdala (BLA) of mice fed a high 3:6 ratio diet, compared with that of mice fed a low 3:6 ratio diet. Similar enhancement was induced by pharmacological expulsion of cholesterol in the neuronal membrane of brain slices from mice fed a low 3:6 ratio diet. CB1 receptor-mediated short-term synaptic plasticity was facilitated in pyramidal neurons of the BLA in mice fed a high 3:6 ratio diet. These results suggest that the ratio of n-3 to n-6 PUFA is a factor regulating fear memory via cannabinoid CB1 receptors.

  14. Role of a gamma-aminobutryic acid (GABA) receptor mutation in the evolution and spread of Diabrotica virgifera virgifera resistance to cyclodiene insecticides

    USDA-ARS?s Scientific Manuscript database

    An alanine to serine amino acid substitution within the Rdl subunit of the gamma-aminobutyric acid (GABA) receptor confers resistance to cyclodiene insecticides in many species. The corn rootworm, Diabrotica virgifera virgifera, is a damaging pest of cultivated corn that was partially controlled by ...

  15. Bile acid regulates c-Jun expression through the orphan nuclear receptor SHP induction in gastric cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Park, Won Il; Park, Min Jung; An, Jin Kwang

    2008-05-02

    Bile reflux is considered to be one of the most important causative factors in gastric carcinogenesis, due to the attendant inflammatory changes in the gastric mucosa. In this study, we have assessed the molecular mechanisms inherent to the contribution of bile acid to the transcriptional regulation of inflammatory-related genes. In this study, we demonstrated that bile acid induced the expression of the SHP orphan nuclear receptor at the transcriptional level via c-Jun activation. Bile acid also enhanced the protein interaction of NF-{kappa}B and SHP, thereby resulting in an increase in c-Jun expression and the production of the inflammatory cytokine, TNF{alpha}.more » These results indicate that bile acid performs a critical function in the regulation of the induction of inflammatory-related genes in gastric cells, and that bile acid-mediated gene expression provides a pre-clue for the development of gastric cellular malformation.« less

  16. Behavioral effects of gamma-hydroxybutyrate, its precursor gamma-butyrolactone, and GABA(B) receptor agonists: time course and differential antagonism by the GABA(B) receptor antagonist 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP35348).

    PubMed

    Koek, Wouter; Mercer, Susan L; Coop, Andrew; France, Charles P

    2009-09-01

    Gamma-hydroxybutyrate (GHB) is used therapeutically and recreationally. The mechanism by which GHB produces its therapeutic and recreational effects is not entirely clear, although GABA(B) receptors seem to play an important role. This role could be complex, because there are indications that different GABA(B) receptor mechanisms mediate the effects of GHB and the prototypical GABA(B) receptor agonist baclofen. To further explore possible differences in underlying GABA(B) receptor mechanisms, the present study examined the effects of GHB and baclofen on operant responding and their antagonism by the GABA(B) receptor antagonist 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP35348). Pigeons were trained to peck a key for access to food during response periods that started at different times after the beginning of the session. In these pigeons, GHB, its precursor gamma-butyrolactone (GBL), and the GABA(B) receptor agonists baclofen and 3-aminopropyl(methyl)phosphinic acid hydrochloride (SKF97541) decreased the rate of responding in a dose- and time-dependent manner. CGP35348 shifted the dose-response curve of each agonist to the right, but the magnitude of the shift differed among the agonists. Schild analysis yielded a pA(2) value of CGP35348 to antagonize GHB and GBL [i.e., 3.9 (3.7-4.2)] that was different (P = 0.0011) from the pA(2) value to antagonize baclofen and SKF97541 [i.e., 4.5 (4.4-4.7)]. This finding is further evidence that the GABA(B) receptor mechanisms mediating the effects of GHB and prototypical GABA(B) receptor agonists are not identical. A better understanding of the similarities and differences between these mechanisms, and their involvement in the therapeutic effects of GHB and baclofen, could lead to more effective medications with fewer adverse effects.

  17. Adiponectin receptor 1 conserves docosahexaenoic acid and promotes photoreceptor cell survival

    PubMed Central

    Rice, Dennis S.; Calandria, Jorgelina M.; Gordon, William C.; Jun, Bokkyoo; Zhou, Yongdong; Gelfman, Claire M.; Li, Songhua; Jin, Minghao; Knott, Eric J.; Chang, Bo; Abuin, Alex; Issa, Tawfik; Potter, David; Platt, Kenneth A.; Bazan, Nicolas G.

    2015-01-01

    The identification of pathways necessary for photoreceptor and retinal pigment epithelium (RPE) function is critical to uncover therapies for blindness. Here we report the discovery of adiponectin receptor 1 (AdipoR1) as a regulator of these cells’ functions. Docosahexaenoic acid (DHA) is avidly retained in photoreceptors, while mechanisms controlling DHA uptake and retention are unknown. Thus, we demonstrate that AdipoR1 ablation results in DHA reduction. In situ hybridization reveals photoreceptor and RPE cell AdipoR1 expression, blunted in AdipoR1−/− mice. We also find decreased photoreceptor-specific phosphatidylcholine containing very long-chain polyunsaturated fatty acids and severely attenuated electroretinograms. These changes precede progressive photoreceptor degeneration in AdipoR1−/− mice. RPE-rich eyecup cultures from AdipoR1−/− reveal impaired DHA uptake. AdipoR1 overexpression in RPE cells enhances DHA uptake, whereas AdipoR1 silencing has the opposite effect. These results establish AdipoR1 as a regulatory switch of DHA uptake, retention, conservation and elongation in photoreceptors and RPE, thus preserving photoreceptor cell integrity. PMID:25736573

  18. All-trans retinoic acid regulates hepatic bile acid homeostasis

    PubMed Central

    Yang, Fan; He, Yuqi; Liu, Hui-Xin; Tsuei, Jessica; Jiang, Xiaoyue; Yang, Li; Wang, Zheng-Tao; Wan, Yu-Jui Yvonne

    2014-01-01

    Retinoic acid (RA) and bile acids share common roles in regulating lipid homeostasis and insulin sensitivity. In addition, the receptor for RA (retinoid x receptor) is a permissive partner of the receptor for bile acids, farnesoid x receptor (FXR/NR1H4). Thus, RA can activate the FXR-mediated pathway as well. The current study was designed to understand the effect of all-trans RA on bile acid homeostasis. Mice were fed an all-trans RA-supplemented diet and the expression of 46 genes that participate in regulating bile acid homeostasis was studied. The data showed that all-trans RA has a profound effect in regulating genes involved in synthesis and transport of bile acids. All-trans RA treatment reduced the gene expression levels of Cyp7a1, Cyp8b1, and Akr1d1, which are involved in bile acid synthesis. All-trans RA also decreased the hepatic mRNA levels of Lrh-1 (Nr5a2) and Hnf4α (Nr2a1), which positively regulate the gene expression of Cyp7a1 and Cyp8b1. Moreover, all-trans RA induced the gene expression levels of negative regulators of bile acid synthesis including hepatic Fgfr4, Fxr, and Shp (Nr0b2) as well as ileal Fgf15. All-trans RA also decreased the expression of Abcb11 and Slc51b, which have a role in bile acid transport. Consistently, all-trans RA reduced hepatic bile acid levels and the ratio of CA/CDCA, as demonstrated by liquid chromatography-mass spectrometry. The data suggest that all-trans RA-induced SHP may contribute to the inhibition of CYP7A1 and CYP8B1, which in turn reduces bile acid synthesis and affects lipid absorption in the gastrointestinal tract. PMID:25175738

  19. Structure--activity studies for alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropanoic acid receptors: acidic hydroxyphenylalanines.

    PubMed

    Hill, R A; Wallace, L J; Miller, D D; Weinstein, D M; Shams, G; Tai, H; Layer, R T; Willins, D; Uretsky, N J; Danthi, S N

    1997-09-26

    Antagonists of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropanoic acid (AMPA) receptors may have therapeutic potential as psychotropic agents. A series of mononitro- and dinitro-2- and 3-hydroxyphenylalanines was prepared, and their activity compared with willardiine, 5-nitrowillardiine, AMPA, and 2,4,5-trihydroxyphenylalanine (6-hydroxydopa) as inhibitors of specific [3H]AMPA and [3H]kainate binding in rat brain homogenates. The most active compounds were highly acidic (pKa 3-4), namely, 2-hydroxy-3,5-dinitro-DL-phenylalanine (13; [3H]AMPA IC50 approximately equal to 25 microM) and 3-hydroxy-2,4-dinitro-DL-phenylalanine (19; [3H]AMPA IC50 approximately equal to 5 microM). Two other dinitro-3-hydroxyphenylalanines, and 3,5-dinitro-DL-tyrosine, were considerably less active. Various mononitrohydroxyphenylalanines, which are less acidic, were also less active or inactive, and 2- and 3-hydroxyphenylalanine (o- and m-tyrosine) were inactive. Compounds 13 and 19, DL-willardiine (pKa 9.3, [3H]AMPA IC50 = 2 microM), and 5-nitro-DL-willardiine (pKa 6.4, [3H]AMPA IC50 = 0.2 microM) displayed AMPA > kainate selectivity in binding studies. Compound 19 was an AMPA-like agonist, but 13 was an antagonist in an AMPA-evoked norepinephrine release assay in rat hippocampal nerve endings. Also, compound 13 injected into the rat ventral pallidum antagonized the locomotor activity elicited by systemic amphetamine.

  20. The 17,18-epoxyeicosatetraenoic acid-G protein-coupled receptor 40 axis ameliorates contact hypersensitivity by inhibiting neutrophil mobility in mice and cynomolgus macaques.

    PubMed

    Nagatake, Takahiro; Shiogama, Yumiko; Inoue, Asuka; Kikuta, Junichi; Honda, Tetsuya; Tiwari, Prabha; Kishi, Takayuki; Yanagisawa, Atsushi; Isobe, Yosuke; Matsumoto, Naomi; Shimojou, Michiko; Morimoto, Sakiko; Suzuki, Hidehiko; Hirata, So-Ichiro; Steneberg, Pär; Edlund, Helena; Aoki, Junken; Arita, Makoto; Kiyono, Hiroshi; Yasutomi, Yasuhiro; Ishii, Masaru; Kabashima, Kenji; Kunisawa, Jun

    2017-12-27

    Metabolites of eicosapentaenoic acid exert various physiologic actions. 17,18-Epoxyeicosatetraenoic acid (17,18-EpETE) is a recently identified new class of antiallergic and anti-inflammatory lipid metabolite of eicosapentaenoic acid, but its effects on skin inflammation and the underlying mechanisms remain to be investigated. We evaluated the effectiveness of 17,18-EpETE for control of contact hypersensitivity in mice and cynomolgus macaques. We further sought to reveal underlying mechanisms by identifying the responsible receptor and cellular target of 17,18-EpETE. Contact hypersensitivity was induced by topical application of 2,4-dinitrofluorobenzene. Skin inflammation and immune cell populations were analyzed by using flow cytometric, immunohistologic, and quantitative RT-PCR analyses. Neutrophil mobility was examined by means of imaging analysis in vivo and neutrophil culture in vitro. The receptor for 17,18-EpETE was identified by using the TGF-α shedding assay, and the receptor's involvement in the anti-inflammatory effects of 17,18-EpETE was examined by using KO mice and specific inhibitor treatment. We found that preventive or therapeutic treatment with 17,18-EpETE ameliorated contact hypersensitivity by inhibiting neutrophil mobility in mice and cynomolgus macaques. 17,18-EpETE was recognized by G protein-coupled receptor (GPR) 40 (also known as free fatty acid receptor 1) and inhibited chemoattractant-induced Rac activation and pseudopod formation in neutrophils. Indeed, the antiallergic inflammatory effect of 17,18-EpETE was abolished in the absence or inhibition of GPR40. 17,18-EpETE inhibits neutrophil mobility through GPR40 activation, which is a potential therapeutic target to control allergic inflammatory diseases. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  1. The type 1 lysophosphatidic acid receptor is a target for therapy in bone metastases

    PubMed Central

    Boucharaba, Ahmed; Serre, Claire-Marie; Guglielmi, Julien; Bordet, Jean-Claude; Clézardin, Philippe; Peyruchaud, Olivier

    2006-01-01

    Platelet-derived lysophosphatidic acid (LPA) supports the progression of breast and ovarian cancer metastasis to bone. The mechanisms through which LPA promotes bone metastasis formation are, however, unknown. Here we report that silencing of the type 1 LPA receptor (LPA1) in cancer cells blocks the production of tumor-derived cytokines that are potent activators of osteoclast-mediated bone destruction and significantly reduces the progression of osteolytic bone metastases. Moreover, functional blockade of LPA action on its cognate receptor LPA1 using a pharmacological antagonist mimics the effects of silencing LPA1 in tumor cells in vitro and substantially reduces bone metastasis progression in animals. Overall, these results suggest that inhibition of platelet-derived LPA action on LPA1 expressed by tumor cells may be a promising therapeutic target for patients with bone metastases. PMID:16769891

  2. Phaseic Acid, an Endogenous and Reversible Inhibitor of Glutamate Receptors in Mouse Brain*

    PubMed Central

    Hou, Sheng Tao; Jiang, Susan X.; Zaharia, L. Irina; Han, Xiumei; Benson, Chantel L.; Slinn, Jacqueline; Abrams, Suzanne R.

    2016-01-01

    Phaseic acid (PA) is a phytohormone regulating important physiological functions in higher plants. Here, we show the presence of naturally occurring (−)-PA in mouse and rat brains. (−)-PA is exclusively present in the choroid plexus and the cerebral vascular endothelial cells. Purified (−)-PA has no toxicity and protects cultured cortical neurons against glutamate toxicity through reversible inhibition of glutamate receptors. Focal occlusion of the middle cerebral artery elicited a significant induction in (−)-PA expression in the cerebrospinal fluid but not in the peripheral blood. Importantly, (−)-PA induction only occurred in the penumbra area, indicting a protective role of PA in the brain. Indeed, elevating the (−)-PA level in the brain reduced ischemic brain injury, whereas reducing the (−)-PA level using a monoclonal antibody against (−)-PA increased ischemic injury. Collectively, these studies showed for the first time that (−)-PA is an endogenous neuroprotective molecule capable of reversibly inhibiting glutamate receptors during ischemic brain injury. PMID:27864367

  3. Phaseic Acid, an Endogenous and Reversible Inhibitor of Glutamate Receptors in Mouse Brain.

    PubMed

    Hou, Sheng Tao; Jiang, Susan X; Zaharia, L Irina; Han, Xiumei; Benson, Chantel L; Slinn, Jacqueline; Abrams, Suzanne R

    2016-12-30

    Phaseic acid (PA) is a phytohormone regulating important physiological functions in higher plants. Here, we show the presence of naturally occurring (-)-PA in mouse and rat brains. (-)-PA is exclusively present in the choroid plexus and the cerebral vascular endothelial cells. Purified (-)-PA has no toxicity and protects cultured cortical neurons against glutamate toxicity through reversible inhibition of glutamate receptors. Focal occlusion of the middle cerebral artery elicited a significant induction in (-)-PA expression in the cerebrospinal fluid but not in the peripheral blood. Importantly, (-)-PA induction only occurred in the penumbra area, indicting a protective role of PA in the brain. Indeed, elevating the (-)-PA level in the brain reduced ischemic brain injury, whereas reducing the (-)-PA level using a monoclonal antibody against (-)-PA increased ischemic injury. Collectively, these studies showed for the first time that (-)-PA is an endogenous neuroprotective molecule capable of reversibly inhibiting glutamate receptors during ischemic brain injury. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Mechanisms controlling nucleic acid-sensing Toll-like receptors.

    PubMed

    Miyake, Kensuke; Shibata, Takuma; Ohto, Umeharu; Shimizu, Toshiyuki; Saitoh, Shin-Ichiroh; Fukui, Ryutaro; Murakami, Yusuke

    2018-03-08

    Nucleic acid (NA)-sensing Toll-like receptors (TLRs) respond to DNA/RNA derived from pathogens and dead cells. Structural studies have revealed a variety of molecular mechanisms by which TLRs sense NAs. Double-stranded RNA and single-stranded DNA directly bind to TLR3 and TLR9, respectively, whereas TLR7 and TLR8 bind to nucleosides and oligoribonucleotides derived from RNAs. Activation of ligand-bound TLRs is influenced by the functional status of TLRs. Proteolytic cleavage of NA-sensing TLRs enables ligand-dependent TLR dimerization. Trafficking of ligand-activated TLRs in endosomal and lysosomal compartments is requisite for production of type I interferons. Activation of NA-sensing TLRs is required for the control of viruses such as herpes simplex virus and endogenous retroviruses. On the other hand, excessive activation of NA-sensing TLRs drives disease progression in a variety of inflammatory diseases including systemic lupus erythematosus, heart failure, arthritis and non-alcoholic steatohepatitis. NA-sensing TLRs are targets for therapeutic intervention in these diseases. We here focus on our recent progresses in our understanding of NA-sensing TLRs.

  5. A Receptor on Acid.

    PubMed

    Chen, Qiuyan; Tesmer, John J G

    2017-01-26

    Wacker et al. report the crystal structure of LSD in complex with one of its major targets in the brain, the 5-HT 2B receptor, the first such structure for any psychedelic drug. The results shed light on the molecular mechanisms underlying its ability to induce hallucinations with greater duration and potency than closely related compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. (+)Lysergic acid diethylamide, but not its nonhallucinogenic congeners, is a potent serotonin 5HT1C receptor agonist

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burris, K.D.; Breeding, M.; Sanders-Bush, E.

    Activation of central serotonin 5HT2 receptors is believed to be the primary mechanism whereby lysergic acid diethylamide (LSD) and other hallucinogens induce psychoactive effects. This hypothesis is based on extensive radioligand binding and electrophysiological and behavioral studies in laboratory animals. However, the pharmacological profiles of 5HT2 and 5HT1C receptors are similar, making it difficult to distinguish between effects due to activation of one or the other receptor. For this reason, it was of interest to investigate the interaction of LSD with 5HT1C receptors. Agonist-stimulated phosphoinositide hydrolysis in rat choroid plexus was used as a direct measure of 5HT1C receptor activation.more » (+)LSD potently stimulated phosphoinositide hydrolysis in intact choroid plexus and in cultures of choroid plexus epithelial cells, with EC50 values of 9 and 26 nM, respectively. The effect of (+)LSD in both systems was blocked by 5HT receptor antagonists with an order of activity consistent with interaction at 5HT1C receptors. Neither (+)-2-bromo-LSD nor lisuride, two nonhallucinogenic congeners of LSD, were able to stimulate 5HT1C receptors in cultured cells or intact choroid plexus. In contrast, lisuride, like (+)LSD, is a partial agonist at 5HT2 receptors in cerebral cortex slices and in NIH 3T3 cells transfected with 5HT2 receptor cDNA. The present finding that (+)LSD, but not its nonhallucinogenic congeners, is a 5HT1C receptor agonist suggests a possible role for these receptors in mediating the psychoactive effects of LSD.« less

  7. Dopamine D2High receptors stimulated by phencyclidines, lysergic acid diethylamide, salvinorin A, and modafinil.

    PubMed

    Seeman, Philip; Guan, Hong-Chang; Hirbec, Hélène

    2009-08-01

    Although it is commonly stated that phencyclidine is an antagonist at ionotropic glutamate receptors, there has been little measure of its potency on other receptors in brain tissue. Although we previously reported that phencyclidine stimulated cloned-dopamine D2Long and D2Short receptors, others reported that phencyclidine did not stimulate D2 receptors in homogenates of rat brain striatum. This study, therefore, examined whether phencyclidine and other hallucinogens and psychostimulants could stimulate the incorporation of [(35)S]GTP-gamma-S into D2 receptors in homogenates of rat brain striatum, using the same conditions as previously used to study the cloned D2 receptors. Using 10 microM dopamine to define 100% stimulation, phencyclidine elicited a maximum incorporation of 46% in rat striata, with a half-maximum concentration of 70 nM for phencyclidine, when compared with 80 nM for dopamine, 89 nM for salvinorin A (48 nM for D2Long), 105 nM for lysergic acid diethylamide (LSD), 120 nM for R-modafinil, 710 nM for dizocilpine, 1030 nM for ketamine, and >10,000 nM for S-modafinil. These compounds also inhibited the binding of the D2-selective ligand [(3)H]domperidone. The incorporation was inhibited by the presence of 200 microM guanylylimidodiphosphate and also by D2 blockade, using 10 microM S-sulpiride, but not by D1 blockade with 10 microM SCH23390. Hypertonic buffer containing 150 mM NaCl inhibited the stimulation by phencyclidine, which may explain negative results by others. It is concluded that phencyclidine and other psychostimulants and hallucinogens can stimulate dopamine D2 receptors at concentrations related to their behavioral actions.

  8. Fatty acid amide hydrolase (FAAH) inhibition enhances memory acquisition through activation of PPAR-α nuclear receptors

    PubMed Central

    Mazzola, Carmen; Medalie, Julie; Scherma, Maria; Panlilio, Leigh V.; Solinas, Marcello; Tanda, Gianluigi; Drago, Filippo; Cadet, Jean Lud; Goldberg, Steven R.; Yasar, Sevil

    2009-01-01

    Inhibitors of fatty acid amide hydrolase (FAAH) increase endogenous levels of anandamide (a cannabinoid CB1-receptor ligand) and oleoylethanolamide and palmitoylethanolamide (OEA and PEA, ligands for α-type peroxisome proliferator-activated nuclear receptors, PPAR-α) when and where they are naturally released in the brain. Using a passive-avoidance task in rats, we found that memory acquisition was enhanced by the FAAH inhibitor URB597 or by the PPAR-α agonist WY14643, and these enhancements were blocked by the PPAR-α antagonist MK886. These findings demonstrate novel mechanisms for memory enhancement by activation of PPAR-α, either directly by administering a PPAR-α agonist or indirectly by administering a FAAH inhibitor. PMID:19403796

  9. Absence of γ-aminobutyric acid-a receptor potentiation in central hypersomnolence disorders.

    PubMed

    Dauvilliers, Yves; Evangelista, Elisa; Lopez, Regis; Barateau, Lucie; Jaussent, Isabelle; Cens, Thierry; Rousset, Matthieu; Charnet, Pierre

    2016-08-01

    The pathophysiology of idiopathic hypersomnia (IH) remains unclear. Recently, cerebrospinal fluid (CSF)-induced enhancement of γ-aminobutyric acid (GABA)-A receptor activity was found in patients with IH compared to controls. Fifteen unrelated patients (2 males and 13 females) affected with typical IH, 12 patients (9 males and 3 females) with narcolepsy type 1, and 15 controls (9 males and 6 females) with unspecified hypersomnolence (n = 7) and miscellaneous neurological conditions (n = 8) were included. A lumbar puncture was performed in all participants to measure CSF hypocretin-1 and GABA-A response. We used a voltage-clamp assay on Xenopus oocytes injected with the RNAs that encode the α1 β2 γ2 or the α2 β2 γ2 subunits of the human GABA-A receptor. A sequence of 6 different applications (GABA, GABA/CSF, and CSF alone) with 2 to 4 oocytes per CSF sample was performed in a whole-cell voltage-clamp assay. Representative current traces from oocytes expressing human α1 β2 γ2 or α2 β2 γ2 GABA-A receptors were recorded in response to 6 successive puffs of GABA diluted in the survival medium (SM), showing stable and reliable response. GABA puffs diluted in SM/CSF solution or SM/CSF solution alone showed no significant differences in the CSF of IH, narcolepsy, or control groups. No associations were found between GABA responses, demographic features, disease duration, or disease severity in the whole population or within groups. Using the Xenopus oocyte assay, we found an absence of GABA-A receptor potentiation with CSF from patients with central hypersomnolence disorders, with no significant differences between hypocretin-deficient and non-hypocretin-deficient patients compared to controls. Ann Neurol 2016;80:259-268. © 2016 American Neurological Association.

  10. Design and Synthesis of a Series of l-trans-4-Substituted Prolines as Selective Antagonists for the Ionotropic Glutamate Receptors Including Functional and X-ray Crystallographic Studies of New Subtype Selective Kainic Acid Receptor Subtype 1 (GluK1) Antagonist (2S,4R)-4-(2-Carboxyphenoxy)pyrrolidine-2-carboxylic Acid.

    PubMed

    Krogsgaard-Larsen, Niels; Delgar, Claudia G; Koch, Karina; Brown, Patricia M G E; Møller, Charlotte; Han, Liwei; Huynh, Tri H V; Hansen, Stinne W; Nielsen, Birgitte; Bowie, Derek; Pickering, Darryl S; Kastrup, Jette Sandholm; Frydenvang, Karla; Bunch, Lennart

    2017-01-12

    Ionotropic glutamate receptor antagonists are valuable tool compounds for studies of neurological pathways in the central nervous system. On the basis of rational ligand design, a new class of selective antagonists, represented by (2S,4R)-4-(2-carboxyphenoxy)pyrrolidine-2-carboxylic acid (1b), for cloned homomeric kainic acid receptors subtype 1 (GluK1) was attained (K i = 4 μM). In a functional assay, 1b displayed full antagonist activity with IC 50 = 6 ± 2 μM. A crystal structure was obtained of 1b when bound in the ligand binding domain of GluK1. A domain opening of 13-14° was seen compared to the structure with glutamate, consistent with 1b being an antagonist. A structure-activity relationship study showed that the chemical nature of the tethering atom (C, O, or S) linking the pyrrolidine ring and the phenyl ring plays a key role in the receptor selectivity profile and that substituents on the phenyl ring are well accommodated by the GluK1 receptor.

  11. A High Content Drug Screen Identifies Ursolic Acid as an Inhibitor of Amyloid β Protein Interactions with Its Receptor CD36*

    PubMed Central

    Wilkinson, Kim; Boyd, Justin D.; Glicksman, Marcie; Moore, Kathryn J.; El Khoury, Joseph

    2011-01-01

    A pathological hallmark of Alzheimer disease (AD) is deposition of amyloid β (Aβ) in the brain. Aβ binds to microglia via a receptor complex that includes CD36 leading to production of proinflammatory cytokines and neurotoxic reactive oxygen species and subsequent neurodegeneration. Interruption of Aβ binding to CD36 is a potential therapeutic strategy for AD. To identify pharmacologic inhibitors of Aβ binding to CD36, we developed a 384-well plate assay for binding of fluorescently labeled Aβ to Chinese hamster ovary cells stably expressing human CD36 (CHO-CD36) and screened an Food and Drug Administration-approved compound library. The assay was optimized based on the cells' tolerance to dimethyl sulfoxide, Aβ concentration, time required for Aβ binding, reproducibility, and signal-to-background ratio. Using this assay, we identified four compounds as potential inhibitors of Aβ binding to CD36. These compounds were ursolic acid, ellipticine, zoxazolamine, and homomoschatoline. Of these compounds, only ursolic acid, a naturally occurring pentacyclic triterpenoid, successfully inhibited binding of Aβ to CHO-CD36 cells in a dose-dependent manner. The ursolic acid effect reached a plateau at ∼20 μm, with a maximal inhibition of 64%. Ursolic acid also blocked binding of Aβ to microglial cells and subsequent ROS production. Our data indicate that cell-based high-content screening of small molecule libraries for their ability to block binding of Aβ to its receptors is a useful tool to identify novel inhibitors of receptors involved in AD pathogenesis. Our data also suggest that ursolic acid is a potential therapeutic agent for AD via its ability to block Aβ-CD36 interactions. PMID:21835916

  12. Substitution of lysine-181 to aspartic acid in the third transmembrane region of the endothelin (ET) type B receptor selectively reduces its high-affinity binding with ET-3 peptide.

    PubMed

    Mauzy, C; Wu, L H; Egloff, A M; Mirzadegan, T; Chung, F Z

    1992-01-01

    In the G protein-coupled receptor family, a highly conserved aspartic acid located within the third transmembrane domain has been shown to be involved in ligand binding. Within the endothelin (ET) peptide receptor family, this aspartic acid has been replaced by a lysine. To assess the importance of this residue in ET binding, the lysine (position 181) of rat ET type B receptor was replaced by an aspartic acid. The effects on ligand binding and phosphoinositide turnover of both the wild-type and K181D mutant receptors were examined using transient receptor expression in COS-7 cells. Using [125I]ET-1 as the radioactive peptide ligand in displacement binding studies, the wild-type receptor displayed a typical non-isopeptide-selective binding profile with similar IC50 values (0.2-0.6 nM) for all three ET peptides (ET-1, ET-2, and ET-3). The mutant receptor showed an increase in IC50 values for ET-1 (5 nM), ET-2 (27 nM), and ET-3 (127 nM). The K181D mutant receptor still elicited full inositol phosphate (IP) accumulation responses in the presence of saturating concentrations of ETs (10 nM of ET-1, 100 nM of ET-2, or 1 microM of ET-3), indicating that the mutation did not affect G protein coupling.

  13. Rapid assessment response (RAR) study: drug use and health risk - Pretoria, South Africa

    PubMed Central

    2011-01-01

    Background Within a ten year period South Africa has developed a substantial illicit drug market. Data on HIV risk among drug using populations clearly indicate high levels of HIV risk behaviour due to the sharing of injecting equipment and/or drug-related unprotected sex. While there is international evidence on and experience with adequate responses, limited responses addressing drug use and drug-use-related HIV and other health risks are witnessed in South Africa. This study aimed to explore the emerging problem of drug-related HIV transmission and to stimulate the development of adequate health services for the drug users, by linking international expertise and local research. Methods A Rapid Assessment and Response (RAR) methodology was adopted for the study. For individual and focus group interviews a semi-structured questionnaire was utilised that addressed key issues. Interviews were conducted with a total of 84 key informant (KI) participants, 63 drug user KI participants (49 males, 14 females) and 21 KI service providers (8 male, 13 female). Results and Discussion Adverse living conditions and poor education levels were cited as making access to treatment harder, especially for those living in disadvantaged areas. Heroin was found to be the substance most available and used in a problematic way within the Pretoria area. Participants were not fully aware of the concrete health risks involved in drug use, and the vague ideas held appear not to allow for concrete measures to protect themselves. Knowledge with regards to substance related HIV/AIDS transmission is not yet widespread, with some information sources disseminating incorrect or unspecific information. Conclusions The implementation of pragmatic harm-reduction and other evidence-based public health care policies that are designed to reduce the harmful consequences associated with substance use and HIV/AIDS should be considered. HIV testing and treatment services also need to be made available in

  14. Components of the CCR4-NOT complex function as nuclear hormone receptor coactivators via association with the NRC-interacting Factor NIF-1.

    PubMed

    Garapaty, Shivani; Mahajan, Muktar A; Samuels, Herbert H

    2008-03-14

    CCR4-NOT is an evolutionarily conserved, multicomponent complex known to be involved in transcription as well as mRNA degradation. Various subunits (e.g. CNOT1 and CNOT7/CAF1) have been reported to be involved in influencing nuclear hormone receptor activities. Here, we show that CCR4/CNOT6 and RCD1/CNOT9, members of the CCR4-NOT complex, potentiate nuclear receptor activity. RCD1 interacts in vivo and in vitro with NIF-1 (NRC-interacting factor), a previously characterized nuclear receptor cotransducer that activates nuclear receptors via its interaction with NRC. As with NIF-1, RCD1 and CCR4 do not directly associate with nuclear receptors; however, they enhance ligand-dependent transcriptional activation by nuclear hormone receptors. CCR4 mediates its effect through the ligand binding domain of nuclear receptors and small interference RNA-mediated silencing of endogenous CCR4 results in a marked decrease in nuclear receptor activation. Furthermore, knockdown of CCR4 results in an attenuated stimulation of RARalpha target genes (e.g. Sox9 and HoxA1) as shown by quantitative PCR assays. The silencing of endogenous NIF-1 also resulted in a comparable decrease in the RAR-mediated induction of both Sox9 and HoxA1. Furthermore, CCR4 associates in vivo with NIF-1. In addition, the CCR4-enhanced transcriptional activation by nuclear receptors is dependent on NIF-1. The small interference RNA-mediated knockdown of NIF-1 blocks the ligand-dependent potentiating effect of CCR4. Our results suggest that CCR4 plays a role in the regulation of certain endogenous RARalpha target genes and that RCD1 and CCR4 might mediate their function through their interaction with NIF-1.

  15. A single amino acid residue controls Ca2+ signaling by an octopamine receptor from Drosophila melanogaster.

    PubMed

    Hoff, Max; Balfanz, Sabine; Ehling, Petra; Gensch, Thomas; Baumann, Arnd

    2011-07-01

    Rhythmic activity of cells and cellular networks plays an important role in physiology. In the nervous system oscillations of electrical activity and/or second messenger concentrations are important to synchronize neuronal activity. At the molecular level, rhythmic activity can be initiated by different routes. We have recently shown that an octopamine-activated G-protein-coupled receptor (GPCR; DmOctα1Rb, CG3856) from Drosophila initiates Ca(2+) oscillations. Here, we have unraveled the molecular basis of cellular Ca(2+) signaling controlled by the DmOctα1Rb receptor using a combination of pharmacological intervention, site-directed mutagenesis, and functional cellular Ca(2+) imaging on heterologously expressed receptors. Phosphorylation of a single amino acid residue in the third intracellular loop of the GPCR by PKC is necessary and sufficient to desensitize the receptor. From its desensitized state, DmOctα1Rb is resensitized by dephosphorylation, and a new Ca(2+) signal occurs on octopamine stimulation. Our findings show that transient changes of the receptor's surface profile have a strong effect on its physiological signaling properties. We expect that the detailed knowledge of DmOctα1Rb-dependent signal transduction fosters the identification of specific drugs that can be used for GPCR-mediated pest control, since octopamine serves important physiological and behavioral functions in arthropods.

  16. Interactions between Human Liver Fatty Acid Binding Protein and Peroxisome Proliferator Activated Receptor Selective Drugs

    PubMed Central

    Velkov, Tony

    2013-01-01

    Fatty acid binding proteins (FABPs) act as intracellular shuttles for fatty acids as well as lipophilic xenobiotics to the nucleus, where these ligands are released to a group of nuclear receptors called the peroxisome proliferator activated receptors (PPARs). PPAR mediated gene activation is ultimately involved in maintenance of cellular homeostasis through the transcriptional regulation of metabolic enzymes and transporters that target the activating ligand. Here we show that liver- (L-) FABP displays a high binding affinity for PPAR subtype selective drugs. NMR chemical shift perturbation mapping and proteolytic protection experiments show that the binding of the PPAR subtype selective drugs produces conformational changes that stabilize the portal region of L-FABP. NMR chemical shift perturbation studies also revealed that L-FABP can form a complex with the PPAR ligand binding domain (LBD) of PPARα. This protein-protein interaction may represent a mechanism for facilitating the activation of PPAR transcriptional activity via the direct channeling of ligands between the binding pocket of L-FABP and the PPARαLBD. The role of L-FABP in the delivery of ligands directly to PPARα via this channeling mechanism has important implications for regulatory pathways that mediate xenobiotic responses and host protection in tissues such as the small intestine and the liver where L-FABP is highly expressed. PMID:23476633

  17. Toll/Interleukin-1 Receptor Domain Derived from TcpC (TIR-TcpC) Ameliorates Experimental Autoimmune Arthritis by Down-modulating Th17 Cell Response*

    PubMed Central

    Pasi, Shweta; Kant, Ravi; Surolia, Avadhesha

    2016-01-01

    Evasion through immunomodulation is one of the several strategies adopted by pathogens to prolong their survival within the host. One such pathogen, Escherichia coli CFT073, utilizes an immunomodulatory protein, TcpC, to combat the host's innate immune defense. TcpC abrogates the function of MyD88 in macrophages, thus perturbing all the signaling processes that involve this adaptor protein. Although central to various signaling pathways initiated by IL-1, IL-18, and toll-like receptors, the precise contribution of MyD88 to the development of autoimmunity, particularly rheumatoid arthritis, still needs extensive exploration. Herein, by using the toll/interleukin-1 receptor (TIR) domain homologous C-terminal motif of TcpC, i.e. TIR-TcpC, we found MyD88 to be critical for the induction and progression of rheumatoid arthritis through its pivotal role in the development of Th17 cells, the subset of CD4+ T-cells widely implicated in various autoimmune disorders. The TIR-TcpC mediated inhibition of signaling through MyD88, and subsequent amelioration of experimental autoimmune arthritis was observed to be an outcome of perturbations in the NFκB-RORγt (RAR-related orphan receptor γt) axis. PMID:27022030

  18. Bile Acid Metabolism in Liver Pathobiology

    PubMed Central

    Chiang, John Y. L.; Ferrell, Jessica M.

    2018-01-01

    Bile acids facilitate intestinal nutrient absorption and biliary cholesterol secretion to maintain bile acid homeostasis, which is essential for protecting liver and other tissues and cells from cholesterol and bile acid toxicity. Bile acid metabolism is tightly regulated by bile acid synthesis in the liver and bile acid biotransformation in the intestine. Bile acids are endogenous ligands that activate a complex network of nuclear receptor farnesoid X receptor and membrane G protein-coupled bile acid receptor-1 to regulate hepatic lipid and glucose metabolic homeostasis and energy metabolism. The gut-to-liver axis plays a critical role in the regulation of enterohepatic circulation of bile acids, bile acid pool size, and bile acid composition. Bile acids control gut bacteria overgrowth, and gut bacteria metabolize bile acids to regulate host metabolism. Alteration of bile acid metabolism by high-fat diets, sleep disruption, alcohol, and drugs reshapes gut microbiome and causes dysbiosis, obesity, and metabolic disorders. Gender differences in bile acid metabolism, FXR signaling, and gut microbiota have been linked to higher prevalence of fatty liver disease and hepatocellular carcinoma in males. Alteration of bile acid homeostasis contributes to cholestatic liver diseases, inflammatory diseases in the digestive system, obesity, and diabetes. Bile acid-activated receptors are potential therapeutic targets for developing drugs to treat metabolic disorders. PMID:29325602

  19. Aromatic D-amino acids act as chemoattractant factors for human leukocytes through a G protein-coupled receptor, GPR109B.

    PubMed

    Irukayama-Tomobe, Yoko; Tanaka, Hirokazu; Yokomizo, Takehiko; Hashidate-Yoshida, Tomomi; Yanagisawa, Masashi; Sakurai, Takeshi

    2009-03-10

    GPR109B (HM74) is a putative G protein-coupled receptor (GPCR) whose cognate ligands have yet to be characterized. GPR109B shows a high degree of sequence similarity to GPR109A, another GPCR that was identified as a high-affinity nicotinic acid (niacin) receptor. However, the affinity of nicotinic acid to GPR109B is very low. In this study, we found that certain aromatic D-amino acids, including D-phenylalanine, D-tryptophan, and the metabolite of the latter, D-kynurenine, decreased the activity of adenylate cyclase in cells transfected with GPR109B cDNA through activation of pertussis toxin (PTX)-sensitive G proteins. These D-amino acids also elicited a transient rise of intracellular Ca(2+) level in cells expressing GPR109B in a PTX-sensitive manner. In contrast, these D-amino acids did not show any effects on cells expressing GPR109A. We found that the GPR109B mRNA is abundantly expressed in human neutrophils. D-phenylalanine and D-tryptophan induced a transient increase of intracellular Ca(2+) level and a reduction of cAMP levels in human neutrophils. Furthermore, knockdown of GPR109B by RNA interference inhibited the D-amino acids-induced decrease of cellular cAMP levels in human neutrophils. These D-amino acids induced chemotactic activity of freshly prepared human neutrophils. We also found that D-phenylalanine and D-tryptophan induced chemotactic responses in Jurkat cells transfected with the GPR109B cDNA but not in mock-transfected Jurkat cells. These results suggest that these aromatic D-amino acids elicit a chemotactic response in human neutrophils via activation of GPR109B.

  20. Endogenous neuropeptide Y depresses the afferent signaling of gastric acid challenge to the mouse brainstem via neuropeptide Y type Y2 and Y4 receptors.

    PubMed

    Wultsch, T; Painsipp, E; Thoeringer, C K; Herzog, H; Sperk, G; Holzer, P

    2005-01-01

    Vagal afferents signal gastric acid challenge to the nucleus tractus solitarii of the rat brainstem. This study investigated whether nucleus tractus solitarii neurons in the mouse also respond to gastric acid challenge and whether this chemonociceptive input is modified by neuropeptide Y acting via neuropeptide Y receptors of type Y2 or Y4. The gastric mucosa of female mice was exposed to different concentrations of HCl or saline, excitation of neurons in the nucleus tractus solitarii visualized by c-Fos immunohistochemistry, gastric emptying deduced from the gastric volume recovery, and gastric lesion formation evaluated by planimetry. Relative to saline, intragastric HCl (0.15-0.35 M) increased the number of c-Fos-expressing cells in the nucleus tractus solitarii in a concentration-dependent manner, inhibited gastric emptying but failed to cause significant hemorrhagic injury in the stomach. Mice in which the Y2 or Y4 receptor gene had been deleted responded to gastric acid challenge with a significantly higher expression of c-Fos in the nucleus tractus solitarii, the increases amounting to 39 and 31%, respectively. The HCl-induced inhibition of gastric emptying was not altered by deletion of the Y2 or Y4 receptor gene. BIIE0246 ((S)-N2-[[1-[2-[4-[(R,S)-5,11-dihydro-6(6H)-oxodibenz[b,e] azepin-11-yl]-1-piperazinyl]-2-oxoethyl]cyclopentyl] acetyl]-N-[2-[1,2-dihydro-3,5 (4H)-dioxo-1,2-diphenyl-3H-1,2,4-triazol-4-yl]ethyl]-argininamide; 0.03 mmol/kg s.c.), a Y2 receptor antagonist which does not cross the blood-brain barrier, did not modify the c-Fos response to gastric acid challenge. The Y2 receptor agonist peptide YY-(3-36) (0.1 mg/kg intraperitoneally) likewise failed to alter the gastric HCl-evoked expression of c-Fos in the nucleus tractus solitarii. BIIE0246, however, prevented the effect of peptide YY-(3-36) to inhibit gastric acid secretion as deduced from measurement of intragastric pH. The current data indicate that gastric challenge with acid

  1. Inhibition of Smooth Muscle Proliferation by Urea-Based Alkanoic Acids via Peroxisome Proliferator-Activated Receptor α–Dependent Repression of Cyclin D1

    PubMed Central

    Ng, Valerie Y.; Morisseau, Christophe; Falck, John R.; Hammock, Bruce D.; Kroetz, Deanna L.

    2007-01-01

    Objective Proliferation of smooth muscle cells is implicated in cardiovascular complications. Previously, a urea-based soluble epoxide hydrolase inhibitor was shown to attenuate smooth muscle cell proliferation. We examined the possibility that urea-based alkanoic acids activate the nuclear receptor peroxisome proliferator-activated receptor α (PPARα) and the role of PPARα in smooth muscle cell proliferation. Methods and Results Alkanoic acids transactivated PPARα, induced binding of PPARα to its response element, and significantly induced the expression of PPARα-responsive genes, showing their function as PPARα agonists. Furthermore, the alkanoic acids attenuated platelet-derived growth factor–induced smooth muscle cell proliferation via repression of cyclin D1 expression. Using small interfering RNA to decrease endogenous PPARα expression, it was determined that PPARα was partially involved in the cyclin D1 repression. The antiproliferative effects of alkanoic acids may also be attributed to their inhibitory effects on soluble epoxide hydrolase, because epoxyeicosatrienoic acids alone inhibited smooth muscle cell proliferation. Conclusions These results show that attenuation of smooth muscle cell proliferation by urea-based alkanoic acids is mediated, in part, by the activation of PPARα. These acids may be useful for designing therapeutics to treat diseases characterized by excessive smooth muscle cell proliferation. PMID:16917105

  2. Lysergic acid diethylamide (LSD) administration selectively downregulates serotonin2 receptors in rat brain.

    PubMed

    Buckholtz, N S; Zhou, D F; Freedman, D X; Potter, W Z

    1990-04-01

    A dosage regimen of lysergic acid diethylamide (LSD) that reliably produces behavioral tolerance in rats was evaluated for effects on neurotransmitter receptor binding in rat brain using a variety of radioligands selective for amine receptor subtypes. Daily administration of LSD [130 micrograms/kg (0.27 mumol/kg) intraperitoneally (IP)] for 5 days produced a decrease in serotonin2 (5-hydroxytryptamine2, 5-HT2) binding in cortex (measured 24 hours after the last drug administration) but did not affect binding to other receptor systems (5-HT1A, 5-HT1B, beta-adrenergic, alpha 1- or alpha 2-adrenergic, D2-dopaminergic) or to a recognition site for 5-HT uptake. The decrease was evident within 3 days of LSD administration but was not demonstrable after the first LSD dose. Following 5 days of LSD administration the decrease was still present 48 hours, but not 96 hours, after the last administration. The indole hallucinogen psilocybin [1.0 mg/kg (3.5 mumol/kg) for 8 days] also produced a significant decrease in 5HT2 binding, but neither the nonhallucinogenic analog bromo-LSD [1.3 mg/kg (2.4 mumol/kg) for 5 days] nor mescaline [10 mg/kg (40.3 mumol/kg) for 5 or 10 days] affected 5-HT2 binding. These observations suggest that LSD and other indole hallucinogens may act as 5-HT2 agonists at postsynaptic 5-HT2 receptors. Decreased 5-HT2 binding strikingly parallels the development and loss of behavioral tolerance seen with repeated LSD administration, but the decreased binding per se cannot explain the gamut of behavioral tolerance and cross-tolerance phenomena among the indole and phenylethylamine hallucinogens.

  3. Rapid Assessment Response (RAR) study: drug use, health and systemic risks--Emthonjeni Correctional Centre, Pretoria, South Africa.

    PubMed

    Dos Santos, Monika M L; Trautmann, Franz; Wolvaardt, Gustaaf; Palakatsela, Romeo

    2014-04-03

    Correctional centre populations are one of the populations most at risk of contracting HIV infection for many reasons, such as unprotected sex, violence, rape and tattooing with contaminated equipment. Specific data on drug users in correctional centres is not available for the majority of countries, including South Africa. The study aimed to identify the attitudes and knowledge of key informant (KI) offender and correctional centre staff regarding drug use, health and systemic-related problems so as to facilitate the long-term planning of activities in the field of drug-use prevention and systems strengthening in correctional centres, including suggestions for the development of appropriate intervention and rehabilitation programmes. A Rapid Assessment Response (RAR) methodology was adopted which included observation, mapping of service providers (SP), KI interviews (staff and offenders) and focus groups (FGs). The study was implemented in Emthonjeni Youth Correctional Centre, Pretoria, South Africa. Fifteen KI staff participants were interviewed and 45 KI offenders. Drug use is fairly prevalent in the centre, with tobacco most commonly smoked, followed by cannabis and heroin. The banning of tobacco has also led to black-market features such as transactional sex, violence, gangsterism and smuggling in order to obtain mainly prohibited tobacco products, as well as illicit substances. HIV, health and systemic-related risk reduction within the Correctional Service sector needs to focus on measures such as improvement of staff capacity and security measures, deregulation of tobacco products and the development and implementation of comprehensive health promotion programmes.

  4. Phosphorylation of a conserved serine in the deoxyribonucleic acid binding domain of nuclear receptors alters intracellular localization.

    PubMed

    Sun, Kai; Montana, Vedrana; Chellappa, Karthikeyani; Brelivet, Yann; Moras, Dino; Maeda, Yutaka; Parpura, Vladimir; Paschal, Bryce M; Sladek, Frances M

    2007-06-01

    Nuclear receptors (NRs) are a superfamily of transcription factors whose genomic functions are known to be activated by lipophilic ligands, but little is known about how to deactivate them or how to turn on their nongenomic functions. One obvious mechanism is to alter the nuclear localization of the receptors. Here, we show that protein kinase C (PKC) phosphorylates a highly conserved serine (Ser) between the two zinc fingers of the DNA binding domain of orphan receptor hepatocyte nuclear factor 4alpha (HNF4alpha). This Ser (S78) is adjacent to several positively charged residues (Arg or Lys), which we show here are involved in nuclear localization of HNF4alpha and are conserved in nearly all other NRs, along with the Ser/threonine (Thr). A phosphomimetic mutant of HNF4alpha (S78D) reduced DNA binding, transactivation ability, and protein stability. It also impaired nuclear localization, an effect that was greatly enhanced in the MODY1 mutant Q268X. Treatment of the hepatocellular carcinoma cell line HepG2 with PKC activator phorbol 12-myristate 13-acetate also resulted in increased cytoplasmic localization of HNF4alpha as well as decreased endogenous HNF4alpha protein levels in a proteasome-dependent fashion. We also show that PKC phosphorylates the DNA binding domain of other NRs (retinoic acid receptor alpha, retinoid X receptor alpha, and thyroid hormone receptor beta) and that phosphomimetic mutants of the same Ser/Thr result in cytoplasmic localization of retinoid X receptor alpha and peroxisome proliferator-activated receptor alpha. Thus, phosphorylation of this conserved Ser between the two zinc fingers may be a common mechanism for regulating the function of NRs.

  5. Design and synthesis of alkoxyindolyl-3-acetic acid analogs as peroxisome proliferator-activated receptor-γ/δ agonists.

    PubMed

    Gim, Hyo Jin; Li, Hua; Lee, Eun; Ryu, Jae-Ha; Jeon, Raok

    2013-01-15

    A series of carbazole or phenoxazine containing alkoxyindole-3-acetic acid analogs were prepared as PPARγ/δ agonists and their transactivation activities for PPAR receptor subtypes (α, γ and δ) were investigated. Structure-activity relationship studies disclosed the effect of the lipophilic tail, attaching position of the alkoxy group and N-benzyl substitution at indole. Compound 1b was the most potent for PPARδ and 3b for PPARγ. Molecular modeling suggested two different binding modes of our alkoxyindole-3-acetic acid analogs providing the insight into their PPAR activity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Alteration of gene expression in the colon of colorectal cancer model rat by dietary sodium gluconate.

    PubMed

    Kameue, Chiyoko; Tsukahara, Takamitsu; Ushida, Kazunari

    2006-03-01

    Butyrate induces apoptosis of various cancer cell lines in a p53-independent manner and inhibits the proliferation of cancer cells. In a previous report, we reported a significant reduction in tumor incidence in rat colon as a result of dietary sodium gluconate (GNA). The stimulation of apoptosis through enhanced butyrate production in the large intestine was involved in the antitumorigenic effect of GNA. In the present study, a cDNA microarray analysis was performed to investigate the particular mechanism involved in the antitumorigenic effect of GNA. Some up-regulated genes suggested by microarray analysis were further evaluated using real-time PCR. A microarray revealed that GNA regulates the expression of retinoic acid receptor (RAR) and retinoid X receptor (RXR), and several genes known as the target of retinoids in cancer cells. In other words, the antitumorigenic effect of GNA may involve the regulation of the retinoid signaling pathway by butyrate in a retinoid-independent manner.

  7. Gi-coupled γ-aminobutyric acid-B receptors cross-regulate phospholipase C and calcium in airway smooth muscle.

    PubMed

    Mizuta, Kentaro; Mizuta, Fumiko; Xu, Dingbang; Masaki, Eiji; Panettieri, Reynold A; Emala, Charles W

    2011-12-01

    γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian central nervous system, and exerts its actions via both ionotropic (GABA(A)) and metabotropic (GABA(B)) receptors. Although the functional expression of GABA(B) receptors coupled to the G(i) protein was reported for airway smooth muscle, the role of GABA(B) receptors in airway responsiveness remains unclear. We investigated whether G(i)-coupled GABA(B) receptors cross-regulate phospholipase C (PLC), an enzyme classically regulated by G(q)-coupled receptors in human airway smooth muscle cells. Both the GABA(B)-selective agonist baclofen and the endogenous ligand GABA significantly increased the synthesis of inositol phosphate, whereas GABA(A) receptor agonists, muscimol, and 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol exerted no effect. The baclofen-induced synthesis of inositol phosphate and transient increases in [Ca(2+)](i) were blocked by CGP35348 and CGP55845 (selective GABA(B) antagonists), pertussis toxin (PTX, which inactivates the G(i) protein), gallein (a G(βγ) signaling inhibitor), U73122 (an inhibitor of PLC-β), and xestospongin C, an inositol 1,4,5-triphosphate receptor blocker. Baclofen also potentiated the bradykinin-induced synthesis of inositol phosphate and transient increases in [Ca(2+)](i), which were blocked by CGP35348 or PTX. Moreover, baclofen potentiated the substance P-induced contraction of airway smooth muscle in isolated guinea pig tracheal rings. In conclusion, the stimulation of GABA(B) receptors in human airway smooth muscle cells rapidly mobilizes intracellular Ca(2+) stores by the synthesis of inositol phosphate via the activation of PLC-β, which is stimulated by G(βγ) protein liberated from G(i) proteins coupled to GABA(B) receptors. Furthermore, crosstalk between GABA(B) receptors and G(q)-coupled receptors potentiates the synthesis of inositol phosphate, transient increases in [Ca(2+)](i), and smooth muscle contraction through G

  8. Antidepressant-like effect of folic acid: Involvement of NMDA receptors and L-arginine-nitric oxide-cyclic guanosine monophosphate pathway.

    PubMed

    Brocardo, Patrícia de Souza; Budni, Josiane; Lobato, Kelly Ribas; Kaster, Manuella Pinto; Rodrigues, Ana Lúcia S

    2008-11-19

    Antidepressant-like activity of folic acid in forced swimming test and in the tail suspension test was demonstrated previously by our group. In this study we investigated the involvement of N-methyl-d-aspartate (NMDA) receptors and l-arginine-nitric oxide (NO)-cyclic guanosine monophosphate pathway in its antidepressant-like effect in the forced swimming test in mice. The antidepressant-like effect of folic acid (10 nmol/site, i.c.v.) was prevented by the pretreatment of mice with NMDA (0.1 pmol/site, i.c.v.), l-arginine (750 mg/kg, i.p., substrate for nitric oxide synthase), S-nitroso-N-acetyl-penicillamine (SNAP, 25 microg/site, i.c.v, a NO donor) or sildenafil (5 mg/kg, i.p., phosphodiesterase 5 inhibitor). The administration of 7-nitroindazole (25 and 50 mg/kg, i.p., a specific neuronal nitric oxide synthase (nNOS) inhibitor) or methylene blue (20 mg/kg, i.p., direct inhibitor of both nitric oxide synthase and soluble guanylate cyclase) in combination with a sub-effective dose of folic acid (1 nmol/site, i.c.v.) reduced the immobility time in the FST as compared with either drug alone. Together the results suggest that the antidepressant-like effect of folic acid in the forced swimming test is dependent on an inhibition of either NMDA receptors or NO and cGMP synthesis.

  9. Activation of NMDA receptors in the brainstem, rostral ventromedial medulla, and nucleus reticularis gigantocellularis mediates mechanical hyperalgesia produced by repeated intramuscular injections of acidic saline in rats.

    PubMed

    Da Silva, Luis F; Desantana, Josimari M; Sluka, Kathleen A

    2010-04-01

    Repeated injections of acidic saline into the gastrocnemius muscle induce both muscle and cutaneous hypersensitivity. We have previously shown that microinjection of local anesthetic into either the rostral ventromedial medulla (RVM) or the nucleus reticularis gigantocellularis (NGC) reverses this muscle and cutaneous hypersensitivity. Although prior studies show that NMDA receptors in the RVM play a clear role in mediating visceral and inflammatory hypersensitivity, the role of NMDA receptors in the NGC or in noninflammatory muscle pain is unclear. Therefore, the present study evaluated involvement of the NMDA receptors in the RVM and NGC in muscle and cutaneous hypersensitivity induced by repeated intramuscular injections of acidic saline. Repeated intramuscular injections of acidic saline, 5 days apart, resulted in a bilateral decrease in the withdrawal thresholds of the paw and muscle in all groups 24 hours after the second injection. Microinjection of NMDA receptor antagonists into the RVM reversed both the muscle and cutaneous hypersensitivity. However, microinjection of NMDA receptor antagonists into the NGC only reversed cutaneous but not muscle hypersensitivity. These results suggest that NMDA receptors in the RVM mediate both muscle and cutaneous hypersensitivity, but those in the NGC mediate only cutaneous hypersensitivity after muscle insult. The current study shows that NMDA receptors in supraspinal facilitatory sites maintain noninflammatory muscle pain. Clinical studies in people with chronic widespread, noninflammatory pain, similarly, show alterations in central excitability. Thus, understanding mechanisms in an animal model could lead to improved treatment for patients with chronic muscle pain. Copyright 2010 American Pain Society. Published by Elsevier Inc. All rights reserved.

  10. A Single Amino Acid Residue at Transmembrane Domain 4 of the α Subunit Influences Carisoprodol Direct Gating Efficacy at GABAA Receptors.

    PubMed

    Kumar, Manoj; Kumar, Manish; Freund, John M; Dillon, Glenn H

    2017-09-01

    The muscle relaxant carisoprodol has recently been controlled at the federal level as a Schedule IV drug due to its high abuse potential and consequences of misuse, such as withdrawal syndrome, delusions, seizures, and even death. Recent work has shown that carisoprodol can directly gate and allosterically modulate the type A GABA (GABA A ) receptor. These actions are subunit-dependent; compared with other GABA A receptors, carisoprodol has nominal direct gating effects in α 3 β 2 γ 2 receptors. Here, using site-directed mutagenesis and whole-cell patch-clamp electrophysiology in transiently transfected human embryonic kidney 293 cells, we examined the role of GABA A receptor α subunit transmembrane domain 4 (TM4) amino acids in direct gating and allosteric modulatory actions of carisoprodol. Mutation of α 3 valine at position 440 to leucine (present in the equivalent position in the α 1 subunit) significantly increased the direct gating effects of carisoprodol without affecting its allosteric modulatory effects. The corresponding reverse mutation, α 1(L415V), decreased carisoprodol direct gating potency and efficacy. Analysis of a series of amino acid mutations at the 415 position demonstrated that amino acid volume correlated positively with carisoprodol efficacy, whereas polarity inversely correlated with carisoprodol efficacy. We conclude that α 1(415) of TM4 is involved in the direct gating, but not allosteric modulatory, actions of carisoprodol. In addition, the orientation of alkyl or hydroxyl groups at this position influences direct gating effects. These findings support the likelihood that the direct gating and allosteric modulatory effects of carisoprodol are mediated via distinct binding sites. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

  11. [Effects of ursodeoxycholic acid on the liver plasma membrane fluidity, hepatic glutathione concentration, hepatic estrogen receptors and progesterone receptors in pregnant rats with ethinylestradiol and progesterone induced intrahepatic cholestasis].

    PubMed

    Shi, Qing-yun; Kong, Bei-hua; Ma, Kai-dong; Zhang, Xiang-li; Jiang, Sen

    2003-11-01

    To explore the effects of ursodeoxycholic acid (UDCA) on the fluidity of hepatic plasma membrane, glutathione concentration in liver, hepatic estrogen receptors and progesterone receptors in pregnant rats with ethinylestradiol and progesterone induced intrahepatic cholestasis. sixty clean SD pregnant rats were selected and divided into three groups at random. Since the 13th day of pregnancy after taking blood, normal group was injected subcutaneously with refined vegetable oil 2.5 ml x kg(-1) x d(-1). Control group and treatment group were injected subcutaneously with the solution of progesterone 75 mg x kg(-1) x d(-1) and 17-alpha-ethynylestradio 1.25 mg x kg(-1) x d(-1) till the 17th day. Since the 17th day control group, normal group were fedwish 0.9% natriichloridi solution 5 ml x kg(-1) x d(-1); Treatment group was fedwish UDCA 50 mg x kg(-1) x d(-1) every day. On the 21th day, all rats were killed. Then the livers were collected for study. Membrane fluidity was measured by fluorescence polarization using 1,6-diphenyl-1,3,5-hexatriene (DPH) as a probe. Glutathione concentration was measured by 5,5'-dithionbis (2-nitrobenzoic acid) (DTNB). Estrogen receptors and progesterone receptors were measured by flow cytometry. (1) Hepatic plasma membrane fluidity and glutathione (GSH) concentration: significantly lower level of GSH concentration and higher fluorescence polarization (P) were detected in control group (GSH: 1.13 +/- 0.03, P: 0.149 +/- 0.008) in comparison with normal group (GSH: 2.11 +/- 0.07, P: 0.132 +/- 0.004, P < 0.05). However, Significantly higher level of GSH concentration and lower fluorescence polarization were detected in treatment group (GSH: 1.82 +/- 0.04, P: 0.141 +/- 0.006) in comparison with control group (P < 0.05). The level of GSH concentration and fluorescence polarization were no difference between treatment group and normal group. Hepatic estrogen receptors (ER) and progesterone receptors (PR): The expression of ER and PR in control

  12. Folinic acid treatment for schizophrenia associated with folate receptor autoantibodies.

    PubMed

    Ramaekers, V T; Thöny, B; Sequeira, J M; Ansseau, M; Philippe, P; Boemer, F; Bours, V; Quadros, E V

    2014-12-01

    Auto-antibodies against folate receptor alpha (FRα) at the choroid plexus that block N(5)-methyltetrahydrofolate (MTHF) transfer to the brain were identified in catatonic schizophrenia. Acoustic hallucinations disappeared following folinic acid treatment. Folate transport to the CNS prevents homocysteine accumulation and delivers one-carbon units for methyl-transfer reactions and synthesis of purines. The guanosine derivative tetrahydrobiopterin acts as common co-factor for the enzymes producing dopamine, serotonin and nitric oxide. Our study selected patients with schizophrenia unresponsive to conventional treatment. Serum from these patients with normal plasma homocysteine, folate and vitamin B12 was tested for FR autoantibodies of the blocking type on serial samples each week. Spinal fluid was analyzed for MTHF and the metabolites of pterins, dopamine and serotonin. The clinical response to folinic acid treatment was evaluated. Fifteen of 18 patients (83.3%) had positive serum FR auto-antibodies compared to only 1 in 30 controls (3.3%) (χ(2)=21.6; p<0.0001). FRα antibody titers in patients fluctuated over time varying between negative and high titers, modulating folate flux to the CNS, which explained low CSF folate values in 6 and normal values in 7 patients. The mean±SD for CSF MTHF was diminished compared to previously established controls (t-test: 3.90; p=0.0002). A positive linear correlation existed between CSF MTHF and biopterin levels. CSF dopamine and serotonin metabolites were low or in the lower normal range. Administration of folinic acid (0.3-1mg/kg/day) to 7 participating patients during at least six months resulted in clinical improvement. Assessment of FR auto-antibodies in serum is recommended for schizophrenic patients. Clinical negative or positive symptoms are speculated to be influenced by the level and evolution of FRα antibody titers which determine folate flux to the brain with up- or down-regulation of brain folate intermediates

  13. Similar, but different: structurally related azelaic acid and hexanoic acid trigger differential metabolomic and transcriptomic responses in tobacco cells.

    PubMed

    Djami-Tchatchou, Arnaud T; Ncube, Efficient N; Steenkamp, Paul A; Dubery, Ian A

    2017-11-29

    Plants respond to various stress stimuli by activating an enhanced broad-spectrum defensive ability. The development of novel resistance inducers represents an attractive, alternative crop protection strategy. In this regard, hexanoic acid (Hxa, a chemical elicitor) and azelaic acid (Aza, a natural signaling compound) have been proposed as inducers of plant defense, by means of a priming mechanism. Here, we investigated both the mode of action and the complementarity of Aza and Hxa as priming agents in Nicotiana tabacum cells in support of enhanced defense. Metabolomic analyses identified signatory biomarkers involved in the establishment of a pre-conditioned state following Aza and Hxa treatment. Both inducers affected the metabolomes in a similar manner and generated common biomarkers: caffeoylputrescine glycoside, cis-5-caffeoylquinic acid, feruloylglycoside, feruloyl-3-methoxytyramine glycoside and feruloyl-3-methoxytyramine conjugate. Subsequently, quantitative real time-PCR was used to investigate the expression of inducible defense response genes: phenylalanine ammonia lyase, hydroxycinnamoyl CoA quinate transferase and hydroxycinnamoyl transferase to monitor activation of the early phenylpropanoid pathway and chlorogenic acids metabolism, while ethylene response element-binding protein, small sar1 GTPase, heat shock protein 90, RAR1, SGT1, non-expressor of PR genes 1 and thioredoxin were analyzed to report on signal transduction events. Pathogenesis-related protein 1a and defensin were quantified to investigate the activation of defenses regulated by salicylic acid and jasmonic acid respectively. The qPCR results revealed differential expression kinetics and, in general (except for NPR1, Thionin and PR1a), the relative gene expression ratios observed in the Hxa-treated cells were significantly greater than the expression observed in the cells treated with Aza. The results indicate that Aza and Hxa have a similar priming effect through activation of genes

  14. Phosphatidic acid phospholipase A1 mediates ER–Golgi transit of a family of G protein–coupled receptors

    PubMed Central

    Kunduri, Govind; Yuan, Changqing; Parthibane, Velayoudame; Nyswaner, Katherine M.; Kanwar, Ritu; Nagashima, Kunio; Britt, Steven G.; Mehta, Nickita; Kotu, Varshika; Porterfield, Mindy; Tiemeyer, Michael; Dolph, Patrick J.; Acharya, Usha

    2014-01-01

    The coat protein II (COPII)–coated vesicular system transports newly synthesized secretory and membrane proteins from the endoplasmic reticulum (ER) to the Golgi complex. Recruitment of cargo into COPII vesicles requires an interaction of COPII proteins either with the cargo molecules directly or with cargo receptors for anterograde trafficking. We show that cytosolic phosphatidic acid phospholipase A1 (PAPLA1) interacts with COPII protein family members and is required for the transport of Rh1 (rhodopsin 1), an N-glycosylated G protein–coupled receptor (GPCR), from the ER to the Golgi complex. In papla1 mutants, in the absence of transport to the Golgi, Rh1 is aberrantly glycosylated and is mislocalized. These defects lead to decreased levels of the protein and decreased sensitivity of the photoreceptors to light. Several GPCRs, including other rhodopsins and Bride of sevenless, are similarly affected. Our findings show that a cytosolic protein is necessary for transit of selective transmembrane receptor cargo by the COPII coat for anterograde trafficking. PMID:25002678

  15. A Rationally Designed Agonist Defines Subfamily IIIA Abscisic Acid Receptors As Critical Targets for Manipulating Transpiration.

    PubMed

    Vaidya, Aditya S; Peterson, Francis C; Yarmolinsky, Dmitry; Merilo, Ebe; Verstraeten, Inge; Park, Sang-Youl; Elzinga, Dezi; Kaundal, Amita; Helander, Jonathan; Lozano-Juste, Jorge; Otani, Masato; Wu, Kevin; Jensen, Davin R; Kollist, Hannes; Volkman, Brian F; Cutler, Sean R

    2017-11-17

    Increasing drought and diminishing freshwater supplies have stimulated interest in developing small molecules that can be used to control transpiration. Receptors for the plant hormone abscisic acid (ABA) have emerged as key targets for this application, because ABA controls the apertures of stomata, which in turn regulate transpiration. Here, we describe the rational design of cyanabactin, an ABA receptor agonist that preferentially activates Pyrabactin Resistance 1 (PYR1) with low nanomolar potency. A 1.63 Å X-ray crystallographic structure of cyanabactin in complex with PYR1 illustrates that cyanabactin's arylnitrile mimics ABA's cyclohexenone oxygen and engages the tryptophan lock, a key component required to stabilize activated receptors. Further, its sulfonamide and 4-methylbenzyl substructures mimic ABA's carboxylate and C6 methyl groups, respectively. Isothermal titration calorimetry measurements show that cyanabactin's compact structure provides ready access to high ligand efficiency on a relatively simple scaffold. Cyanabactin treatments reduce Arabidopsis whole-plant stomatal conductance and activate multiple ABA responses, demonstrating that its in vitro potency translates to ABA-like activity in vivo. Genetic analyses show that the effects of cyanabactin, and the previously identified agonist quinabactin, can be abolished by the genetic removal of PYR1 and PYL1, which form subclade A within the dimeric subfamily III receptors. Thus, cyanabactin is a potent and selective agonist with a wide spectrum of ABA-like activities that defines subfamily IIIA receptors as key target sites for manipulating transpiration.

  16. Boronic acid-tethered amphiphilic hyaluronic acid derivative-based nanoassemblies for tumor targeting and penetration.

    PubMed

    Jeong, Jae Young; Hong, Eun-Hye; Lee, Song Yi; Lee, Jae-Young; Song, Jae-Hyoung; Ko, Seung-Hak; Shim, Jae-Seong; Choe, Sunghwa; Kim, Dae-Duk; Ko, Hyun-Jeong; Cho, Hyun-Jong

    2017-04-15

    (3-Aminomethylphenyl)boronic acid (AMPB)-installed hyaluronic acid-ceramide (HACE)-based nanoparticles (NPs), including manassantin B (MB), were fabricated for tumor-targeted delivery. The amine group of AMPB was conjugated to the carboxylic acid group of hyaluronic acid (HA) via amide bond formation, and synthesis was confirmed by spectroscopic methods. HACE-AMPB/MB NPs with a 239-nm mean diameter, narrow size distribution, negative zeta potential, and >90% drug encapsulation efficiency were fabricated. Exposed AMPB in the outer surface of HACE-AMPB NPs (in the aqueous environment) may react with sialic acid of cancer cells. The improved cellular accumulation efficiency, in vitro antitumor efficacy, and tumor penetration efficiency of HACE-AMPB/MB NPs, compared with HACE/MB NPs, in MDA-MB-231 cells (CD44 receptor-positive human breast adenocarcinoma cells) may be based on the CD44 receptor-mediated endocytosis and phenylboronic acid-sialic acid interaction. Enhanced in vivo tumor targetability, infiltration efficiency, and antitumor efficacies of HACE-AMPB NPs, compared with HACE NPs, were observed in a MDA-MB-231 tumor-xenografted mouse model. In addition to passive tumor targeting (based on an enhanced permeability and retention effect) and active tumor targeting (interaction between HA and CD44 receptor), the phenylboronic acid-sialic acid interaction can play important roles in augmented tumor targeting and penetration of HACE-AMPB NPs. STATEMENT OF SIGNIFICANCE: (3-Aminomethylphenyl)boronic acid (AMPB)-tethered hyaluronic acid-ceramide (HACE)-based nanoparticles (NPs), including manassantin B (MB), were fabricated and their tumor targeting and penetration efficiencies were assessed in MDA-MB-231 (CD44 receptor-positive human adenocarcinoma) tumor models. MB, which exhibited antitumor efficacies via the inhibition of angiogenesis and hypoxia inducible factor (HIF)-1, was entrapped in HACE-AMPB NPs in this study. Phenylboronic acid located in the outer surface

  17. Asymmetrical Macromolecular Complex Formation of Lysophosphatidic Acid Receptor 2 (LPA2) Mediates Gradient Sensing in Fibroblasts*

    PubMed Central

    Ren, Aixia; Moon, Changsuk; Zhang, Weiqiang; Sinha, Chandrima; Yarlagadda, Sunitha; Arora, Kavisha; Wang, Xusheng; Yue, Junming; Parthasarathi, Kaushik; Heil-Chapdelaine, Rick; Tigyi, Gabor; Naren, Anjaparavanda P.

    2014-01-01

    Chemotactic migration of fibroblasts toward growth factors relies on their capacity to sense minute extracellular gradients and respond to spatially confined receptor-mediated signals. Currently, mechanisms underlying the gradient sensing of fibroblasts remain poorly understood. Using single-particle tracking methodology, we determined that a lysophosphatidic acid (LPA) gradient induces a spatiotemporally restricted decrease in the mobility of LPA receptor 2 (LPA2) on chemotactic fibroblasts. The onset of decreased LPA2 mobility correlates to the spatial recruitment and coupling to LPA2-interacting proteins that anchor the complex to the cytoskeleton. These localized PDZ motif-mediated macromolecular complexes of LPA2 trigger a Ca2+ puff gradient that governs gradient sensing and directional migration in response to LPA. Disruption of the PDZ motif-mediated assembly of the macromolecular complex of LPA2 disorganizes the gradient of Ca2+ puffs, disrupts gradient sensing, and reduces the directional migration of fibroblasts toward LPA. Our findings illustrate that the asymmetric macromolecular complex formation of chemoattractant receptors mediates gradient sensing and provides a new mechanistic basis for models to describe gradient sensing of fibroblasts. PMID:25542932

  18. Effect of common polymorphisms of the farnesoid X receptor and bile acid transporters on the pharmacokinetics of ursodeoxycholic acid.

    PubMed

    Hu, Miao; Fok, Benny S P; Wo, Siu-Kwan; Lee, Vincent H L; Zuo, Zhong; Tomlinson, Brian

    2016-01-01

    Ursodeoxycholic acid (UDCA), a natural, dihydroxy bile acid, promotes gallstone dissolution and has been attributed with several other beneficial effects. The farnesoid X receptor (FXR) may influence the pharmacokinetics of UDCA by modulating the expression of bile acid transporters. This exploratory study examined whether common functional polymorphisms in FXR and in bile acid transporter genes affect the pharmacokinetics of exogenous UDCA. Polymorphisms in genes for transporters involved in bile acid transport, solute carrier organic anion 1B1 (SLCO1B1) 388A>G and 521T>C, solute carrier 10A1 (SLC10A1) 800 C>T and ATP-binding cassette B11 (ABCB11) 1331T>C, and the FXR -1G>T polymorphism were genotyped in 26 male Chinese subjects who ingested single oral 500-mg doses of UDCA. Plasma concentrations of UDCA and its major conjugate metabolite glycoursodeoxycholic acid (GUDCA) were determined. The mean systemic exposure of UDCA was higher in the five subjects with one copy of the FXR -1G>T variant allele than in those homozygous for the wild-type allele (n = 21) (AUC0-24 h : 38.5 ± 28.2 vs. 20.9 ± 8.0 μg h/mL, P = 0.021), but this difference appeared mainly due to one outlier with the -1GT genotype and elevated baseline and post-treatment UDCA concentrations. After excluding the outlier, body weight was the only factor associated with plasma concentrations of UDCA and there were no significant associations with the other polymorphisms examined. None of the polymorphisms affected the pharmacokinetics of GUDCA. This study showed that the common polymorphisms in bile acid transporters had no significant effect on the pharmacokinetics of exogenous UDCA but an effect of the FXR polymorphism cannot be excluded. © 2015 Wiley Publishing Asia Pty Ltd.

  19. The potent free radical scavenger alpha-lipoic acid improves memory in aged mice: putative relationship to NMDA receptor deficits.

    PubMed

    Stoll, S; Hartmann, H; Cohen, S A; Müller, W E

    1993-12-01

    alpha-Lipoic acid (alpha-LA) improved longer-term memory of aged female NMRI mice in the habituation in the open field test at a dose of 100 mg/kg body weight for 15 days. In a separate experiment, no such effect could be found for young mice. alpha-LA alleviated age-related NMDA receptor deficits (Bmax) without changing muscarinic, benzodiazepine, and alpha 2-adrenergic receptor deficits in aged mice. The carbachol-stimulated accumulation of inositol monophosphates was not changed by the treatment with alpha-LA. These results give tentative support to the hypothesis that alpha-LA improves memory in aged mice, probably by a partial compensation of NMDA receptor deficits. Possible modes of action of alpha-LA based on its free radical scavenger properties are discussed in relation to the membrane hypothesis of aging.

  20. Successful combination immunotherapy of anti-gamma aminobutyric acid (GABA)A receptor antibody-positive encephalitis with extensive multifocal brain lesions.

    PubMed

    Fukami, Yuki; Okada, Hiroaki; Yoshida, Mari; Yamaguchi, Keiji

    2017-08-31

    A 78-year old woman who presented with akinetic mutism was admitted to our hospital. Brain MRI showed multifocal increased T 2 /FLAIR signal with extensive cortical-subcortical involvement. We suspected autoimmune encephalitis and the patient received methylprednisolone pulse. Her conscious level gradually recovered, but later relapsed again and presented with refractory status epilepticus. We treated her with intravenous immunoglobulin, plasma exchange and pulsed cyclophosphamide, with satisfactory response. A brain biopsy showed perivascular lymphocytic infiltrates and reactive gliosis. Anti-gamma aminobutyric acid (GABA) A receptor antibodies test came back to be positive after her recovery, and the diagnosis of anti-GABA A receptor antibody-positive encephalitis was made. This is a very rare case where brain biopsies were performed in a patient with anti-GABA A receptor antibody-positive encephalitis.

  1. Synthesis of new C-25 and C-26 steroidal acids as potential ligands of the nuclear receptors DAF-12, LXR and GR.

    PubMed

    Dansey, María V; Del Fueyo, María C; Veleiro, Adriana S; Di Chenna, Pablo H

    2017-05-01

    A new methodology to obtain C-25 and C-26 steroidal acids starting from pregnenolone is described. Construction of the side chain was achieved by applying the Mukaiyama aldol reaction with a non-hydrolytic work-up to isolate the trapped silyl enol ether with higher yields. Using this methodology we synthesized three new steroidal acids as potential ligands of DAF-12, Liver X and Glucocorticoid nuclear receptors and studied their activity in reporter gene assays. Our results show that replacement of the 21-CH 3 by a 20-keto group in the side chains of the cholestane scaffold of DAF-12 or Liver X receptors ligands causes the loss of the activity. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. A Newly Discovered Antifibrotic Pathway Regulated by Two Fatty Acid Receptors: GPR40 and GPR84.

    PubMed

    Gagnon, Lyne; Leduc, Martin; Thibodeau, Jean-Francois; Zhang, Ming-Zhi; Grouix, Brigitte; Sarra-Bournet, Francois; Gagnon, William; Hince, Kathy; Tremblay, Mikaël; Geerts, Lilianne; Kennedy, Christopher R J; Hébert, Richard L; Gutsol, Alex; Holterman, Chet E; Kamto, Eldjonai; Gervais, Liette; Ouboudinar, Jugurtha; Richard, Jonathan; Felton, Alexandra; Laverdure, Alexandre; Simard, Jean-Christophe; Létourneau, Sylvie; Cloutier, Marie-Pier; Leblond, Francois A; Abbott, Shaun D; Penney, Christopher; Duceppe, Jean-Simon; Zacharie, Boulos; Dupuis, Jocelyn; Calderone, Angelino; Nguyen, Quang T; Harris, Raymond C; Laurin, Pierre

    2018-05-01

    Numerous clinical conditions can lead to organ fibrosis and functional failure. There is a great need for therapies that could effectively target pathophysiological pathways involved in fibrosis. GPR40 and GPR84 are G protein-coupled receptors with free fatty acid ligands and are associated with metabolic and inflammatory disorders. Although GPR40 and GPR84 are involved in diverse physiological processes, no evidence has demonstrated the relevance of GPR40 and GPR84 in fibrosis pathways. Using PBI-4050 (3-pentylbenzeneacetic acid sodium salt), a synthetic analog of a medium-chain fatty acid that displays agonist and antagonist ligand affinity toward GPR40 and GPR84, respectively, we uncovered an antifibrotic pathway involving these receptors. In experiments using Gpr40- and Gpr84-knockout mice in models of kidney fibrosis (unilateral ureteral obstruction, long-term post-acute ischemic injury, and adenine-induced chronic kidney disease), we found that GPR40 is protective and GPR84 is deleterious in these diseases. Moreover, through binding to GPR40 and GPR84, PBI-4050 significantly attenuated fibrosis in many injury contexts, as evidenced by the antifibrotic activity observed in kidney, liver, heart, lung, pancreas, and skin fibrosis models. Therefore, GPR40 and GPR84 may represent promising molecular targets in fibrosis pathways. We conclude that PBI-4050 is a first-in-class compound that may be effective for managing inflammatory and fibrosis-related diseases. Copyright © 2018 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  3. Ionotropic glutamate receptors: regulation by G-protein-coupled receptors.

    PubMed

    Rojas, Asheebo; Dingledine, Raymond

    2013-04-01

    The function of many ion channels is under dynamic control by coincident activation of G-protein-coupled receptors (GPCRs), particularly those coupled to the Gαs and Gαq family members. Such regulation is typically dependent on the subunit composition of the ionotropic receptor or channel as well as the GPCR subtype and the cell-specific panoply of signaling pathways available. Because GPCRs and ion channels are so highly represented among targets of U.S. Food and Drug Administration-approved drugs, functional cross-talk between these drug target classes is likely to underlie many therapeutic and adverse effects of marketed drugs. GPCRs engage a myriad of signaling pathways that involve protein kinases A and C (PKC) and, through PKC and interaction with β-arrestin, Src kinase, and hence the mitogen-activated-protein-kinase cascades. We focus here on the control of ionotropic glutamate receptor function by GPCR signaling because this form of regulation can influence the strength of synaptic plasticity. The amino acid residues phosphorylated by specific kinases have been securely identified in many ionotropic glutamate (iGlu) receptor subunits, but which of these sites are GPCR targets is less well known even when the kinase has been identified. N-methyl-d-aspartate, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and heteromeric kainate receptors are all downstream targets of GPCR signaling pathways. The details of GPCR-iGlu receptor cross-talk should inform a better understanding of how synaptic transmission is regulated and lead to new therapeutic strategies for neuropsychiatric disorders.

  4. 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.

  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 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

  6. Characterization of Triticum aestivum Abscisic Acid Receptors and a Possible Role for These in Mediating Fusairum Head Blight Susceptibility in Wheat

    PubMed Central

    Gordon, Cameron S.; Rajagopalan, Nandhakishore; Risseeuw, Eddy P.; Surpin, Marci; Ball, Fraser J.; Barber, Carla J.; Buhrow, Leann M.; Clark, Shawn M.; Page, Jonathan E.; Todd, Chris D.; Abrams, Suzanne R.; Loewen, Michele C.

    2016-01-01

    Abscisic acid (ABA) is a well-characterized plant hormone, known to mediate developmental aspects as well as both abiotic and biotic stress responses. Notably, the exogenous application of ABA has recently been shown to increase susceptibility to the fungal pathogen Fusarium graminearum, the causative agent of Fusarium head blight (FHB) in wheat and other cereals. However roles and mechanisms associated with ABA’s modulation of pathogen responses remain enigmatic. Here the identification of putative ABA receptors from available genomic databases for Triticum aestivum (bread wheat) and Brachypodium distachyon (a model cereal) are reported. A number of these were cloned for recombinant expression and their functionality as ABA receptors confirmed by in vitro assays against protein phosphatases Type 2Cs. Ligand selectivity profiling of one of the wheat receptors (Ta_PYL2DS_FL) highlighted unique activities compared to Arabidopsis AtPYL5. Mutagenic analysis showed Ta_PYL2DS_FL amino acid D180 as being a critical contributor to this selectivity. Subsequently, a virus induced gene silencing (VIGS) approach was used to knockdown wheat Ta_PYL4AS_A (and similar) in planta, yielding plants with increased early stage resistance to FHB progression and decreased mycotoxin accumulation. Together these results confirm the existence of a family of ABA receptors in wheat and Brachypodium and present insight into factors modulating receptor function at the molecular level. That knockdown of Ta_PYL4AS_A (and similar) leads to early stage FHB resistance highlights novel targets for investigation in the future development of disease resistant crops. PMID:27755583

  7. Characterization of Triticum aestivum Abscisic Acid Receptors and a Possible Role for These in Mediating Fusairum Head Blight Susceptibility in Wheat.

    PubMed

    Gordon, Cameron S; Rajagopalan, Nandhakishore; Risseeuw, Eddy P; Surpin, Marci; Ball, Fraser J; Barber, Carla J; Buhrow, Leann M; Clark, Shawn M; Page, Jonathan E; Todd, Chris D; Abrams, Suzanne R; Loewen, Michele C

    2016-01-01

    Abscisic acid (ABA) is a well-characterized plant hormone, known to mediate developmental aspects as well as both abiotic and biotic stress responses. Notably, the exogenous application of ABA has recently been shown to increase susceptibility to the fungal pathogen Fusarium graminearum, the causative agent of Fusarium head blight (FHB) in wheat and other cereals. However roles and mechanisms associated with ABA's modulation of pathogen responses remain enigmatic. Here the identification of putative ABA receptors from available genomic databases for Triticum aestivum (bread wheat) and Brachypodium distachyon (a model cereal) are reported. A number of these were cloned for recombinant expression and their functionality as ABA receptors confirmed by in vitro assays against protein phosphatases Type 2Cs. Ligand selectivity profiling of one of the wheat receptors (Ta_PYL2DS_FL) highlighted unique activities compared to Arabidopsis AtPYL5. Mutagenic analysis showed Ta_PYL2DS_FL amino acid D180 as being a critical contributor to this selectivity. Subsequently, a virus induced gene silencing (VIGS) approach was used to knockdown wheat Ta_PYL4AS_A (and similar) in planta, yielding plants with increased early stage resistance to FHB progression and decreased mycotoxin accumulation. Together these results confirm the existence of a family of ABA receptors in wheat and Brachypodium and present insight into factors modulating receptor function at the molecular level. That knockdown of Ta_PYL4AS_A (and similar) leads to early stage FHB resistance highlights novel targets for investigation in the future development of disease resistant crops.

  8. Induction of cardiac Angptl4 by dietary fatty acids is mediated by peroxisome proliferator-activated receptor beta/delta and protects against fatty acid-induced oxidative stress.

    PubMed

    Georgiadi, Anastasia; Lichtenstein, Laeticia; Degenhardt, Tatjana; Boekschoten, Mark V; van Bilsen, Marc; Desvergne, Beatrice; Müller, Michael; Kersten, Sander

    2010-06-11

    Although dietary fatty acids are a major fuel for the heart, little is known about the direct effects of dietary fatty acids on gene regulation in the intact heart. To study the effect of dietary fatty acids on cardiac gene expression and explore the functional consequences. Oral administration of synthetic triglycerides composed of one single fatty acid altered cardiac expression of numerous genes, many of which are involved in the oxidative stress response. The gene most significantly and consistently upregulated by dietary fatty acids encoded Angiopoietin-like protein (Angptl)4, a circulating inhibitor of lipoprotein lipase expressed by cardiomyocytes. Induction of Angptl4 by the fatty acid linolenic acid was specifically abolished in peroxisome proliferator-activated receptor (PPAR)beta/delta(-/-) and not PPARalpha(-/-) mice and was blunted on siRNA-mediated PPARbeta/delta knockdown in cultured cardiomyocytes. Consistent with these data, linolenic acid stimulated binding of PPARbeta/delta but not PPARalpha to the Angptl4 gene. Upregulation of Angptl4 resulted in decreased cardiac uptake of plasma triglyceride-derived fatty acids and decreased fatty acid-induced oxidative stress and lipid peroxidation. In contrast, Angptl4 deletion led to enhanced oxidative stress in the heart, both after an acute oral fat load and after prolonged high fat feeding. Stimulation of cardiac Angptl4 gene expression by dietary fatty acids and via PPARbeta/delta is part of a feedback mechanism aimed at protecting the heart against lipid overload and consequently fatty acid-induced oxidative stress.

  9. Increasing human Th17 differentiation through activation of orphan nuclear receptor retinoid acid-related orphan receptor γ (RORγ) by a class of aryl amide compounds.

    PubMed

    Zhang, Wei; Zhang, Jing; Fang, Leiping; Zhou, Ling; Wang, Shuai; Xiang, Zhijun; Li, Yuan; Wisely, Bruce; Zhang, Guifeng; An, Gang; Wang, Yonghui; Leung, Stewart; Zhong, Zhong

    2012-10-01

    In a screen for small-molecule inhibitors of retinoid acid-related orphan receptor γ (RORγ), we fortuitously discovered that a class of aryl amide compounds behaved as functional activators of the interleukin 17 (IL-17) reporter in Jurkat cells. Three of these compounds were selected for further analysis and found to activate the IL-17 reporter with potencies of ∼0.1 μM measured by EC₅₀. These compounds were shown to directly bind to RORγ by circular dichroism-based thermal stability experiments. Furthermore, they can enhance an in vitro Th17 differentiation process in human primary T cells. As RORγ remains an orphan nuclear receptor, discovery of these aryl amide compounds as functional agonists will now provide pharmacological tools for us to dissect functions of RORγ and facilitate drug discovery efforts for immune-modulating therapies.

  10. Role of 5-HT5A and 5-HT1B/1D receptors in the antinociception produced by ergotamine and valerenic acid in the rat formalin test.

    PubMed

    Vidal-Cantú, Guadalupe C; Jiménez-Hernández, Mildred; Rocha-González, Héctor I; Villalón, Carlos M; Granados-Soto, Vinicio; Muñoz-Islas, Enriqueta

    2016-06-15

    Sumatriptan, dihydroergotamine and methysergide inhibit 1% formalin-induced nociception by activation of peripheral 5-HT1B/1D receptors. This study set out to investigate the pharmacological profile of the antinociception produced by intrathecal and intraplantar administration of ergotamine (a 5-HT1B/1D and 5-HT5A/5B receptor agonist) and valerenic acid (a partial agonist at 5-HT5A receptors). Intraplantar injection of 1% formalin in the right hind paw resulted in spontaneous flinching behavior of the injected hindpaw of female Wistar rats. Intrathecal ergotamine (15nmol) or valerenic acid (1 nmol) blocked in a dose dependent manner formalin-induced nociception. The antinociception by intrathecal ergotamine (15nmol) or valerenic acid (1nmol) was partly or completely blocked by intrathecal administration of the antagonists: (i) methiothepin (non-selective 5-HT5A/5B; 0.01-0.1nmol); (ii) SB-699551 (selective 5-HT5A; up to 10nmol); (iii) anti-5-HT5A antibody; (iv) SB-224289 (selective 5-HT1B; 0.1-1nmol); or (v) BRL-15572 (selective 5-HT1D; 0.1-1nmol). Likewise, antinociception by intraplantar ergotamine (15nmol) and valerenic acid (10nmol) was: (i) partially blocked by methiothepin (1nmol), SB-699551 (10nmol) or SB-224289 (1nmol); and (ii) abolished by BRL-15572 (1nmol). The above doses of antagonists (which did not affect per se the formalin-induced nociception) were high enough to completely block their respective receptors. Our results suggest that ergotamine and valerenic acid produce antinociception via 5-HT5A and 5-HT1B/1D receptors located at both spinal and peripheral sites. This provides new evidence for understanding the modulation of nociceptive pathways in inflammatory pain. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Vehicular exhaust particles promote allergic airway inflammation through an aryl hydrocarbon receptor-notch signaling cascade.

    PubMed

    Xia, Mingcan; Viera-Hutchins, Loida; Garcia-Lloret, Maria; Noval Rivas, Magali; Wise, Petra; McGhee, Sean A; Chatila, Zena K; Daher, Nancy; Sioutas, Constantinos; Chatila, Talal A

    2015-08-01

    Traffic-related particulate matter (PM) has been linked to a heightened incidence of asthma and allergic diseases. However, the molecular mechanisms by which PM exposure promotes allergic diseases remain elusive. We sought to determine the expression, function, and regulation of pathways involved in promotion of allergic airway inflammation by PM. We used gene expression transcriptional profiling, in vitro culture assays, and in vivo murine models of allergic airway inflammation. We identified components of the Notch pathway, most notably Jagged 1 (Jag1), as targets of PM induction in human monocytes and murine dendritic cells. PM, especially ultrafine particles, upregulated TH cytokine levels, IgE production, and allergic airway inflammation in mice in a Jag1- and Notch-dependent manner, especially in the context of the proasthmatic IL-4 receptor allele Il4raR576. PM-induced Jag1 expression was mediated by the aryl hydrocarbon receptor (AhR), which bound to and activated AhR response elements in the Jag1 promoter. Pharmacologic antagonism of AhR or its lineage-specific deletion in CD11c(+) cells abrogated the augmentation of airway inflammation by PM. PM activates an AhR-Jag1-Notch cascade to promote allergic airway inflammation in concert with proasthmatic alleles. Copyright © 2015 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  12. Bile Acid Signaling in Metabolic Disease and Drug Therapy

    PubMed Central

    Li, Tiangang

    2014-01-01

    Bile acids are the end products of cholesterol catabolism. Hepatic bile acid synthesis accounts for a major fraction of daily cholesterol turnover in humans. Biliary secretion of bile acids generates bile flow and facilitates hepatobiliary secretion of lipids, lipophilic metabolites, and xenobiotics. In the intestine, bile acids are essential for the absorption, transport, and metabolism of dietary fats and lipid-soluble vitamins. Extensive research in the last 2 decades has unveiled new functions of bile acids as signaling molecules and metabolic integrators. The bile acid–activated nuclear receptors farnesoid X receptor, pregnane X receptor, constitutive androstane receptor, vitamin D receptor, and G protein–coupled bile acid receptor play critical roles in the regulation of lipid, glucose, and energy metabolism, inflammation, and drug metabolism and detoxification. Bile acid synthesis exhibits a strong diurnal rhythm, which is entrained by fasting and refeeding as well as nutrient status and plays an important role for maintaining metabolic homeostasis. Recent research revealed an interaction of liver bile acids and gut microbiota in the regulation of liver metabolism. Circadian disturbance and altered gut microbiota contribute to the pathogenesis of liver diseases, inflammatory bowel diseases, nonalcoholic fatty liver disease, diabetes, and obesity. Bile acids and their derivatives are potential therapeutic agents for treating metabolic diseases of the liver. PMID:25073467

  13. Clofibric acid induces hepatic CYP 2B1/2 via constitutive androstane receptor not via peroxisome proliferator activated receptor alpha in rat.

    PubMed

    Ibrahim, Zein Shaban; Ahmed, Mohamed Mohamed; El-Shazly, Samir Ahmed; Ishizuka, Mayumi; Fujita, Shoichi

    2014-01-01

    Peroxisome proliferator activated receptor α (PPARα) ligands, fibrates used to control hyperlipidemia. We demonstrated CYP2B induction by clofibric acid (CFA) however, the mechanism was not clear. In this study, HepG2 cells transfected with expression plasmid of mouse constitutive androstane receptor (CAR) or PPARα were treated with CFA, phenobarbital (PB) or TCPOBOP. Luciferase assays showed that CFA increased CYP2B1 transcription to the same level as PB, or TCPOBOP in HepG2 transfected with mouse CAR But failed to induce it in PPARα transfected cells. CYP2B expressions were increased with PB or CFA in Wistar female rats (having normal levels of CAR) but not in Wistar Kyoto female rats (having low levels of CAR). The induction of CYP2B by PB or CFA was comparable to nuclear CAR levels. CAR nuclear translocation was induced by CFA in both rat strains. This indicates that fibrates can activate CAR and that fibrates-insulin sensitization effect may occur through CAR, while hypolipidemic effect may operate through PPARα.

  14. Cloning and sequence analysis of the human brain beta-adrenergic receptor. Evolutionary relationship to rodent and avian beta-receptors and porcine muscarinic receptors.

    PubMed

    Chung, F Z; Lentes, K U; Gocayne, J; Fitzgerald, M; Robinson, D; Kerlavage, A R; Fraser, C M; Venter, J C

    1987-01-26

    Two cDNA clones, lambda-CLFV-108 and lambda-CLFV-119, encoding for the beta-adrenergic receptor, have been isolated from a human brain stem cDNA library. One human genomic clone, LCV-517 (20 kb), was characterized by restriction mapping and partial sequencing. The human brain beta-receptor consists of 413 amino acids with a calculated Mr of 46480. The gene contains three potential glucocorticoid receptor-binding sites. The beta-receptor expressed in human brain was homology with rodent (88%) and avian (52%) beta-receptors and with porcine muscarinic cholinergic receptors (31%), supporting our proposal [(1984) Proc. Natl. Acad. Sci. USA 81, 272 276] that adrenergic and muscarinic cholinergic receptors are structurally related. This represents the first cloning of a neurotransmitter receptor gene from human brain.

  15. Bile Acid Metabolism and Signaling

    PubMed Central

    Chiang, John Y. L.

    2015-01-01

    Bile acids are important physiological agents for intestinal nutrient absorption and biliary secretion of lipids, toxic metabolites, and xenobiotics. Bile acids also are signaling molecules and metabolic regulators that activate nuclear receptors and G protein-coupled receptor (GPCR) signaling to regulate hepatic lipid, glucose, and energy homeostasis and maintain metabolic homeostasis. Conversion of cholesterol to bile acids is critical for maintaining cholesterol homeostasis and preventing accumulation of cholesterol, triglycerides, and toxic metabolites, and injury in the liver and other organs. Enterohepatic circulation of bile acids from the liver to intestine and back to the liver plays a central role in nutrient absorption and distribution, and metabolic regulation and homeostasis. This physiological process is regulated by a complex membrane transport system in the liver and intestine regulated by nuclear receptors. Toxic bile acids may cause inflammation, apoptosis, and cell death. On the other hand, bile acid-activated nuclear and GPCR signaling protects against inflammation in liver, intestine, and macrophages. Disorders in bile acid metabolism cause cholestatic liver diseases, dyslipidemia, fatty liver diseases, cardiovascular diseases, and diabetes. Bile acids, bile acid derivatives, and bile acid sequestrants are therapeutic agents for treating chronic liver diseases, obesity, and diabetes in humans. PMID:23897684

  16. Ionotropic Receptors Mediate Drosophila Oviposition Preference through Sour Gustatory Receptor Neurons.

    PubMed

    Chen, Yan; Amrein, Hubert

    2017-09-25

    Carboxylic acids are present in many foods, being especially abundant in fruits. Yet, relatively little is known about how acids are detected by gustatory systems and whether they have a potential role in nutrition or provide other health benefits. Here we identify sour gustatory receptor neurons (GRNs) in tarsal taste sensilla of Drosophila melanogaster. We find that most tarsal sensilla harbor a sour GRN that is specifically activated by carboxylic and mineral acids but does not respond to sweet- and bitter-tasting chemicals or salt. One pair of taste sensilla features two GRNs that respond only to a subset of carboxylic acids and high concentrations of salt. All sour GRNs prominently express two Ionotropic Receptor (IR) genes, IR76b and IR25a, and we show that both these genes are necessary for the detection of acids. Furthermore, we establish that IR25a and IR76b are essential in sour GRNs of females for oviposition preference on acid-containing food. Our investigations reveal that acids activate a unique set of taste cells largely dedicated to sour taste, and they indicate that both pH/proton concentration and the structure of carboxylic acids contribute to sour GRN activation. Together, our studies provide new insights into the cellular and molecular basis of sour taste. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. The interleukin-4 receptor: signal transduction by a hematopoietin receptor.

    PubMed

    Keegan, A D; Pierce, J H

    1994-02-01

    Over the last several years, the receptors for numerous cytokines have been molecularly characterized. Analysis of their amino acid sequences shows that some of these receptors bear certain motifs in their extracellular domains that define a family of receptors called the Hematopoietin receptor superfamily. Significant advances in characterizing the structure, function, and mechanisms of signal transduction have been made for several members of this family. The purpose of this review is to discuss the recent advances made for one of the family members, the interleukin (IL) 4 receptor. Other receptor systems have recently been reviewed elsewhere. The IL-4 receptor consists of, at the minimum, the cloned 140 kDa IL-4-binding chain with the potential for associating with other chains. The IL-4 receptor transduces its signal by activating a tyrosine kinase that phosphorylates cellular substrates, including the receptor itself, and the 170 kDa substrate called 4PS. Phosphorylated 4PS interacts with the SH2 domain of the enzyme PI-3'-kinase and increases its enzymatic activity. These early events in the IL-4 receptor initiated signaling pathway may trigger a series of signals that will ultimately lead to an IL-4 specific biologic outcome.

  18. Gamma-aminobutyric acid (GABA) stimulates pancreatic cancer growth through overexpressing GABAA receptor pi subunit.

    PubMed

    Takehara, Akio; Hosokawa, Masayo; Eguchi, Hidetoshi; Ohigashi, Hiroaki; Ishikawa, Osamu; Nakamura, Yusuke; Nakagawa, Hidewaki

    2007-10-15

    Gamma-aminobutyric acid (GABA) functions primarily as an inhibitory neurotransmitter in the mature central nervous system, and GABA/GABA receptors are also present in nonneural tissues, including cancer, but their precise function in nonneuronal or cancerous cells has thus far been poorly defined. Through the genome-wide cDNA microarray analysis of pancreatic ductal adenocarcinoma (PDAC) cells as well as subsequent reverse transcription-PCR and Northern blot analyses, we identified the overexpression of GABA receptor pi subunit (GABRP) in PDAC cells. We also found the expression of this peripheral type GABAA receptor subunit in few adult human organs. Knockdown of endogenous GABRP expression in PDAC cells by small interfering RNA attenuated PDAC cell growth, suggesting its essential role in PDAC cell viability. Notably, the addition of GABA into the cell culture medium promoted the proliferation of GABRP-expressing PDAC cells, but not GABRP-negative cells, and GABAA receptor antagonists inhibited this growth-promoting effect by GABA. The HEK293 cells constitutively expressing exogenous GABRP revealed the growth-promoting effect of GABA treatment. Furthermore, GABA treatment in GABRP-positive cells increased intracellular Ca2+ levels and activated the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/Erk) cascade. Clinical PDAC tissues contained a higher level of GABA than normal pancreas tissues due to the up-regulation of glutamate decarboxylase 1 expression, suggesting their autocrine/paracrine growth-promoting effect in PDACs. These findings imply that GABA and GABRP could play important roles in PDAC development and progression, and that this pathway can be a promising molecular target for the development of new therapeutic strategies for PDAC.

  19. Activation of mouse and human peroxisome proliferator-activated receptor alpha by perfluoroalkyl acids of different functional groups and chain lengths.

    PubMed

    Wolf, Cynthia J; Takacs, Margy L; Schmid, Judith E; Lau, Christopher; Abbott, Barbara D

    2008-11-01

    Perfluoroalkyl acids (PFAAs) are surfactants used in consumer products and persist in the environment. Some PFAAs elicit adverse effects on rodent development and survival. PFAAs can activate peroxisome proliferator-activated receptor alpha (PPARalpha) and may act via PPARalpha to produce some of their effects. This study evaluated the ability of numerous PFAAs to induce mouse and human PPARalpha activity in a transiently transfected COS-1 cell assay. COS-1 cells were transfected with either a mouse or human PPARalpha receptor-luciferase reporter plasmid. After 24 h, cells were exposed to either negative controls (water or dimethyl sulfoxide, 0.1%); positive control (WY-14643, PPARalpha agonist); perfluorooctanoic acid or perfluorononanoic acid at 0.5-100 microM; perfluorobutanoic acid, perfluorohexanoic acid, perfluorohexane sulfonate, or perfluorodecanoic acid (PFDA) at 5-100 microM; or perfluorobutane sulfonate or perfluorooctane sulfonate at 1-250 microM. After 24 h of exposure, luciferase activity from the plasmid was measured. Each PFAA activated both mouse and human PPARalpha in a concentration-dependent fashion, except PFDA with human PPARalpha. Activation of PPARalpha by PFAA carboxylates was positively correlated with carbon chain length, up to C9. PPARalpha activity was higher in response to carboxylates compared to sulfonates. Activation of mouse PPARalpha was generally higher compared to that of human PPARalpha. We conclude that, in general, (1) PFAAs of increasing carbon backbone chain lengths induce increasing activity of the mouse and human PPARalpha with a few exceptions, (2) PFAA carboxylates are stronger activators of mouse and human PPARalpha than PFAA sulfonates, and (3) in most cases, the mouse PPARalpha appears to be more sensitive to PFAAs than the human PPARalpha in this model.

  20. Daphnia HR96 is a Promiscuous Xenobiotic and Endobiotic Nuclear Receptor

    PubMed Central

    Karimullina, Elina; Li, Yangchun; Ginjupalli, Gautam; Baldwin, William S.

    2012-01-01

    Daphnia pulex is the first crustacean to have its genome sequenced. The genome project provides new insight and data into how an aquatic crustacean may respond to environmental stressors, including toxicants. We cloned Daphnia pulex HR96 (DappuHR96), a nuclear receptor orthologous to the CAR/PXR/VDR group of nuclear receptors. In Drosophila melanogaster, (hormone receptor 96) HR96 responds to phenobarbital exposure and has been hypothesized as a toxicant receptor. Therefore, we set up a transactivation assay to test whether DappuHR96 is a promiscuous receptor activated by xenobiotics and endobiotics similar to the constitutive androstane receptor (CAR) and the pregnane X-receptor (PXR). Transactivation assays performed with a GAL4-HR96 chimera demonstrate that HR96 is a promiscuous toxicant receptor activated by a diverse set of chemicals such as pesticides, hormones, and fatty acids. Several environmental toxicants activate HR96 including estradiol, pyriproxyfen, chlorpyrifos, atrazine, and methane arsonate. We also observed repression of HR96 activity by chemicals such as triclosan, androstanol, and fluoxetine. Nearly 50% of the chemicals tested activated or inhibited HR96. Interestingly, unsaturated fatty acids were common activators or inhibitors of HR96 activity, indicating a link between diet and toxicant response. The omega-6 and omega-9 unsaturated fatty acids linoleic and oleic acid activated HR96, but the omega-3 unsaturated fatty acids alpha-linolenic acid and docosahexaenoic acid inhibited HR96, suggesting that these two distinct sets of lipids perform opposing roles in Daphnia physiology. This also provides a putative mechanism by which the ratio of dietary unsaturated fats may affect the ability of an organism to respond to a toxic insult. In summary, HR96 is a promiscuous nuclear receptor activated by numerous endo- and xenobiotics. PMID:22466357

  1. Dietary ω-3 Polyunsaturated Fatty Acids Inhibit Tumor Growth in Transgenic ApcMin/+ Mice, Correlating with CB1 Receptor Up-Regulation

    PubMed Central

    Notarnicola, Maria; Tutino, Valeria; De Nunzio, Valentina; Dituri, Francesco; Caruso, Maria Gabriella; Giannelli, Gianluigi

    2017-01-01

    Mediterranean diet components, such as olive oil and ω-3 polyunsaturated fatty acids (ω-3 PUFAs), can arrest cell growth and promote cell apoptosis. Recently, olive oil has been demonstrated to modulate type-1 cannabinoid (CB1) receptor gene expression in both human colon cancer cells and rat colon. The aim of this study was to investigate a possible link between olive oil and ω-3 PUFAs effects and CB1 receptor expression in both intestinal and adipose tissue of ApcMin/+ mice. To confirm the role for the CB1 receptor as a negative modulator of cell proliferation in human colon cancer, CB1 receptor gene expression was also detected in tumor tissue and in surrounding normal mucosa of patients with colorectal cancer (CRC). Dietary ω-3 PUFAs significantly inhibited intestinal polyp growth in mice, correlating with CB1 receptor gene and protein expression induction. CB1 receptor gene up-regulation was also detected in adipose tissue, suggesting a close communication between cancer cells and the surrounding environment. Tissue CB1 receptor induction was associated with a concurrent inactivation of the Wnt/β-catenin pathway. Moreover, there was a significant reduction in CB1 receptor gene expression levels in cancer tissue compared to normal surrounding mucosa of patients with CRC, confirming that in cancer the “protective” action of the CB1 receptor is lost. PMID:28245562

  2. The G Protein-Coupled Bile Acid Receptor, TGR5, Stimulates Gallbladder Filling

    PubMed Central

    Li, Tingting; Holmstrom, Sam R.; Kir, Serkan; Umetani, Michihisa; Schmidt, Daniel R.

    2011-01-01

    TGR5 is a G protein-coupled bile acid receptor present in brown adipose tissue and intestine, where its agonism increases energy expenditure and lowers blood glucose. Thus, it is an attractive drug target for treating human metabolic disease. However, TGR5 is also highly expressed in gallbladder, where its functions are less well characterized. Here, we demonstrate that TGR5 stimulates the filling of the gallbladder with bile. Gallbladder volume was increased in wild-type but not Tgr5−/− mice by administration of either the naturally occurring TGR5 agonist, lithocholic acid, or the synthetic TGR5 agonist, INT-777. These effects were independent of fibroblast growth factor 15, an enteric hormone previously shown to stimulate gallbladder filling. Ex vivo analyses using gallbladder tissue showed that TGR5 activation increased cAMP concentrations and caused smooth muscle relaxation in a TGR5-dependent manner. These data reveal a novel, gallbladder-intrinsic mechanism for regulating gallbladder contractility. They further suggest that TGR5 agonists should be assessed for effects on human gallbladder as they are developed for treating metabolic disease. PMID:21454404

  3. Non-classical mechanism of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor channel block by fluoxetine.

    PubMed

    Barygin, Oleg I; Komarova, Margarita S; Tikhonova, Tatiana B; Tikhonov, Denis B

    2015-04-01

    Antidepressants have many targets in the central nervous system. A growing body of data demonstrates the influence of antidepressants on glutamatergic neurotransmission. In the present work, we studied the inhibition of native Ca(2+)-permeable and Ca(2+)-impermeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in rat brain neurons by fluoxetine. The Ca(2+)-impermeable AMPA receptors in CA1 hippocampal pyramidal neurons were weakly affected. The IC50 value for the inhibition of Ca(2+)-permeable AMPA receptors in giant striatal interneurons was 43 ± 7 μM. The inhibition of Ca(2+)-permeable AMPA receptors was voltage dependent, suggesting deep binding in the pore. However, the use dependence of fluoxetine action differed markedly from that of classical AMPA receptor open-channel blockers. Moreover, fluoxetine did not compete with other channel blockers. In contrast to fluoxetine, its membrane-impermeant quaternary analog demonstrated all of the features of channel inhibition typical for open-channel blockers. It is suggested that fluoxetine reaches the binding site through a hydrophobic access pathway. Such a mechanism of block is described for ligands of sodium and calcium channels, but was never found in AMPA receptors. Molecular modeling suggests binding of fluoxetine in the subunit interface; analogous binding was proposed for local anesthetics in closed sodium channels and for benzothiazepines in calcium channels. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  4. Integrating data on the Arabidopsis NPR1/NPR3/NPR4 salicylic acid receptors; a differentiating argument.

    PubMed

    Kuai, Xiahezi; MacLeod, Brandon J; Després, Charles

    2015-01-01

    Salicylic acid (SA) is a mandatory plant metabolite in the deployment of systemic acquired resistance (SAR), a broad-spectrum systemic immune response induced by local inoculation with avirulent pathogens. The NPR1 transcription co-activator is the central node positively regulating SAR. SA was the last of the major hormones to be without a known receptor. Recently, NPR1 was shown to be the direct link between SA and gene activation. This discovery seems to be controversial. NPR1 being an SA-receptor is reminiscent of the mammalian steroid receptors, which are transcription factors whose binding to DNA is dependent on the interaction with a ligand. Unlike steroid receptors, NPR1 does not bind directly to DNA, but is recruited to promoters by the TGA family of transcription factors to form an enhanceosome. In Arabidopsis, NPR1 is part of a multigene family in which two other members, NPR3 and NPR4, have also been shown to interact with SA. NPR3/NPR4 are negative regulators of immunity and act as substrate adaptors for the recruitment of NPR1 to an E3-ubiquitin ligase, leading to its subsequent degradation by the proteasome. In this perspective, we will stress-test in a friendly way the current NPR1/NPR3/NPR4 model.

  5. Altered microRNA regulation of short chain fatty acid receptors in the hypertensive kidney is normalized with hydrogen sulfide supplementation.

    PubMed

    Weber, Gregory J; Foster, Jaleyea; Pushpakumar, Sathnur B; Sen, Utpal

    2018-06-15

    Hypertension affects nearly one third of the adult US population and is a significant risk factor for chronic kidney disease (CKD). An expanding body of recent studies indicates that gut microbiome has crucial roles in regulating physiological processes through, among other mechanisms, one mode of short chain fatty acids (SCFA) and their target receptors. In addition, these SCFA receptors are potential targets of regulation by host miRNAs, however, the mechanisms through which this occurs is not clearly defined. Hydrogen sulfide (H 2 S) is an important gasotransmitter involved in multiple physiological processes and is known to alleviate adverse effects of hypertension such as reducing inflammation in the kidney. To determine the role of host microRNAs in regulating short chain fatty acid receptors in the kidney as well as the gut, C57BL/6J wild-type mice were treated with or without Ang-II and H 2 S donor GYY4137 (GYY) for 4 weeks to assess whether GYY would normalize adverse effects observed in hypertensive mice and whether this was in part due to altered gut microbiome composition. We observed several changes of SCFA receptors, including Olfr78, Gpr41/43 and predicted microRNA regulators in the kidney among the different treatments. Increased expression of inflammatory markers Il6 and Rorc2, along with Tgfβ, were found in the hypertensive kidney. The glomerular filtration rate (GFR) was improved in mice treated with Ang-II + GYY compared with Ang-II only, indicating improved kidney function. The Erysipelotrichia class of bacteria, linked with high fat diets, was enriched in hypertensive animals but reduced with GYY supplementation. These data point towards a role for miRNA regulation of SCFA receptors in hypertensive kidney and are normalized by H 2 S supplementation. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Molecular pharmacology of promiscuous seven transmembrane receptors sensing organic nutrients.

    PubMed

    Wellendorph, Petrine; Johansen, Lars Dan; Bräuner-Osborne, Hans

    2009-09-01

    A number of highly promiscuous seven transmembrane (7TM) receptors have been cloned and characterized within the last few years. It is noteworthy that many of these receptors are activated broadly by amino acids, proteolytic degradation products, carbohydrates, or free fatty acids and are expressed in taste tissue, the gastrointestinal tract, endocrine glands, adipose tissue, and/or kidney. These receptors thus hold the potential to act as sensors of food intake, regulating, for example, release of incretin hormones from the gut, insulin/glucagon from the pancreas, and leptin from adipose tissue. The promiscuous tendency in ligand recognition of these receptors is in contrast to the typical specific interaction with one physiological agonist seen for most receptors, which challenges the classic "lock-and-key" concept. We here review the molecular mechanisms of nutrient sensing of the calcium-sensing receptor, the G protein-coupled receptor family C, group 6, subtype A (GPRC6A), and the taste1 receptor T1R1/T1R3, which are sensing L-alpha-amino acids, the carbohydrate-sensing T1R2/T1R3 receptor, the proteolytic degradation product sensor GPR93 (also termed GPR92), and the free fatty acid (FFA) sensing receptors FFA1, FFA2, FFA3, GPR84, and GPR120. The involvement of the individual receptors in sensing of food intake has been validated to different degrees because of limited availability of specific pharmacological tools and/or receptor knockout mice. However, as a group, the receptors represent potential drug targets, to treat, for example, type II diabetes by mimicking food intake by potent agonists or positive allosteric modulators. The ligand-receptor interactions of the promiscuous receptors of organic nutrients thus remain an interesting subject of emerging functional importance.

  7. Activation of the omega-3 fatty acid receptor GPR120 mediates anti-inflammatory actions in immortalized hypothalamic neurons.

    PubMed

    Wellhauser, Leigh; Belsham, Denise D

    2014-03-27

    Overnutrition and the ensuing hypothalamic inflammation is a major perpetuating factor in the development of metabolic diseases, such as obesity and diabetes. Inflamed neurons of the CNS fail to properly regulate energy homeostasis leading to pathogenic changes in glucose handling, feeding, and body weight. Hypothalamic neurons are particularly sensitive to pro-inflammatory signals derived locally and peripherally, and it is these neurons that become inflamed first upon high fat feeding. Given the prevalence of metabolic disease, efforts are underway to identify therapeutic targets for this inflammatory state. At least in the periphery, omega-3 fatty acids and their receptor, G-protein coupled receptor 120 (GPR120), have emerged as putative targets. The role for GPR120 in the hypothalamus or CNS in general is poorly understood. Here we introduce a novel, immortalized cell model derived from the rat hypothalamus, rHypoE-7, to study GPR120 activation at the level of the individual neuron. Gene expression levels of pro-inflammatory cytokines were studied by quantitative reverse transcriptase-PCR (qRT-PCR) upon exposure to tumor necrosis factor α (TNFα) treatment in the presence or absence of the polyunsaturated omega-3 fatty acid docosahexaenoic acid (DHA). Signal transduction pathway involvement was also studied using phospho-specific antibodies to key proteins by western blot analysis. Importantly, rHypoE-7 cells exhibit a transcriptional and translational inflammatory response upon exposure to TNFα and express abundant levels of GPR120, which is functionally responsive to DHA. DHA pretreatment prevents the inflammatory state and this effect was inhibited by the reduction of endogenous GPR120 levels. GPR120 activates both AKT (protein kinase b) and ERK (extracellular signal-regulated kinase); however, the anti-inflammatory action of this omega-3 fatty acid (FA) receptor is AKT- and ERK-independent and likely involves the GPR120-transforming growth factor

  8. Sigma-1 receptor regulates Tau phosphorylation and axon extension by shaping p35 turnover via myristic acid.

    PubMed

    Tsai, Shang-Yi A; Pokrass, Michael J; Klauer, Neal R; Nohara, Hiroshi; Su, Tsung-Ping

    2015-05-26

    Dysregulation of cyclin-dependent kinase 5 (cdk5) per relative concentrations of its activators p35 and p25 is implicated in neurodegenerative diseases. P35 has a short t½ and undergoes rapid proteasomal degradation in its membrane-bound myristoylated form. P35 is converted by calpain to p25, which, along with an extended t½, promotes aberrant activation of cdk5 and causes abnormal hyperphosphorylation of tau, thus leading to the formation of neurofibrillary tangles. The sigma-1 receptor (Sig-1R) is an endoplasmic reticulum chaperone that is implicated in neuronal survival. However, the specific role of the Sig-1R in neurodegeneration is unclear. Here we found that Sig-1Rs regulate proper tau phosphorylation and axon extension by promoting p35 turnover through the receptor's interaction with myristic acid. In Sig-1R-KO neurons, a greater accumulation of p35 is seen, which results from neither elevated transcription of p35 nor disrupted calpain activity, but rather to the slower degradation of p35. In contrast, Sig-1R overexpression causes a decrease of p35. Sig-1R-KO neurons exhibit shorter axons with lower densities. Myristic acid is found here to bind Sig-1R as an agonist that causes the dissociation of Sig-1R from its cognate partner binding immunoglobulin protein. Remarkably, treatment of Sig-1R-KO neurons with exogenous myristic acid mitigates p35 accumulation, diminishes tau phosphorylation, and restores axon elongation. Our results define the involvement of Sig-1Rs in neurodegeneration and provide a mechanistic explanation that Sig-1Rs help maintain proper tau phosphorylation by potentially carrying and providing myristic acid to p35 for enhanced p35 degradation to circumvent the formation of overreactive cdk5/p25.

  9. Activation of type 2 cannabinoid receptors (CB2R) promotes fatty acid oxidation through the SIRT1/PGC-1α pathway

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zheng, Xuqin; Sun, Tao; Wang, Xiaodong, E-mail: xdwang666@hotmail.com

    2013-07-05

    Highlights: •TC, a CB2R specific agonist, stimulates SIRT1 activity by PKA/CREB pathway. •TC promotes PGC-1α transcriptional activity by increasing its deacetylation. •TC increases the expression of genes linked to FAO and promotes the rate of FAO. •The effects of TC in FAO are dependent on CB2R. •Suggesting CB2R as a target to treat diseases with lipid dysregulation. -- Abstract: Abnormal fatty acid oxidation has been associated with obesity and type 2 diabetes. At the transcriptional level, peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α) has been reported to strongly increase the ability of hormone nuclear receptors PPARα and ERRα to drive transcriptionmore » of fatty acid oxidation enzymes. In this study, we report that a specific agonist of the type 2 cannabinoid receptor (CB2R) can lead to fatty acid oxidation through the PGC-1α pathway. We have found that CB2R is expressed in differentiated C2C12 myotubes, and that use of the specific agonist trans-caryophyllene (TC) stimulates sirtuin 1 (SIRT1) deacetylase activity by increasing the phosphorylation of cAMP response element-binding protein (CREB), thus leading to increased levels of PGC-1α deacetylation. This use of TC treatment increases the expression of genes linked to the fatty acid oxidation pathway in a SIRT1/PGC-1α-dependent mechanism and also drastically accelerates the rate of complete fatty acid oxidation in C2C12 myotubes, neither of which occur when CB2R mRNA is knocked down using siRNA. These results reveal that activation of CB2R by a selective agonist promotes lipid oxidation through a signaling/transcriptional pathway. Our findings imply that pharmacological manipulation of CB2R may provide therapeutic possibilities to treat metabolic diseases associated with lipid dysregulation.« less

  10. Attenuation of excitatory amino acid toxicity by metabotropic glutamate receptor agonists and aniracetam in primary cultures of cerebellar granule cells.

    PubMed

    Pizzi, M; Fallacara, C; Arrighi, V; Memo, M; Spano, P F

    1993-08-01

    Activation of glutamate ionotropic receptors represents the primary event in the neurotoxicity process triggered by excitatory amino acids. We demonstrate here that the concentration-dependent stimulation of metabotropic glutamate receptor (mGluR) by the selective agonist trans-1-aminocyclopentane-1,3-dicarboxylate or by quisqualate counteracts both glutamate- and kainate-induced neurotoxicity in primary cultures of rat cerebellar granule cells. The mGluR-evoked responses are potentiated by aniracetam, which per se also elicits neuroprotection. Aniracetam concentration-dependently counteracted glutamate-, kainate-, or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-induced cell death and greatly facilitated neuroprotective response achieved by different concentrations of both quisqualate and trans-1-aminocyclopentane-1,3-dicarboxylate. In addition, aniracetam potentiated the mGluR-coupled stimulation of phospholipase C, as revealed by the measurement of 3H-inositol phosphate formation. Thus, mGluRs could be a suitable target for novel pharmacological strategies pointing to the treatment of neurodegenerative diseases.

  11. Purple sweet potato color attenuates domoic acid-induced cognitive deficits by promoting estrogen receptor-α-mediated mitochondrial biogenesis signaling in mice.

    PubMed

    Lu, Jun; Wu, Dong-Mei; Zheng, Yuan-Lin; Hu, Bin; Cheng, Wei; Zhang, Zi-Feng

    2012-02-01

    Recent findings suggest that endoplasmic reticulum stress may be involved in the pathogenesis of domoic acid-induced neurodegeneration. Purple sweet potato color, a class of naturally occurring anthocyanins, has beneficial health and biological effects. Recent studies have also shown that anthocyanins have estrogenic activity and can enhance estrogen receptor-α expression. In this study, we evaluated the effect of purple sweet potato color on cognitive deficits induced by hippocampal mitochondrial dysfunction in domoic acid-treated mice and explored the potential mechanisms underlying this effect. Our results showed that the oral administration of purple sweet potato color to domoic acid-treated mice significantly improved their behavioral performance in a step-through passive avoidance task and a Morris water maze task. These improvements were mediated, at least in part, by a stimulation of estrogen receptor-α-mediated mitochondrial biogenesis signaling and by decreases in the expression of p47phox and gp91phox. Decreases in reactive oxygen species and protein carbonylation were also observed, along with a blockade of the endoplasmic reticulum stress pathway. Furthermore, purple sweet potato color significantly suppressed endoplasmic reticulum stress-induced apoptosis, which prevented neuron loss and restored the expression of memory-related proteins. However, knockdown of estrogen receptor-α using short hairpin RNA only partially blocked the neuroprotective effects of purple sweet potato color in the hippocampus of mice cotreated with purple sweet potato color and domoic acid, indicating that purple sweet potato color acts through multiple pathways. These results suggest that purple sweet potato color could be a possible candidate for the prevention and treatment of cognitive deficits in excitotoxic and other brain disorders. Crown Copyright © 2011. Published by Elsevier Inc. All rights reserved.

  12. The Bile Acid Receptor TGR5 Does Not Interact with β-Arrestins or Traffic to Endosomes but Transmits Sustained Signals from Plasma Membrane Rafts*

    PubMed Central

    Jensen, Dane D.; Godfrey, Cody B.; Niklas, Christian; Canals, Meritxell; Kocan, Martina; Poole, Daniel P.; Murphy, Jane E.; Alemi, Farzad; Cottrell, Graeme S.; Korbmacher, Christoph; Lambert, Nevin A.; Bunnett, Nigel W.; Corvera, Carlos U.

    2013-01-01

    TGR5 is a G protein-coupled receptor that mediates bile acid (BA) effects on energy balance, inflammation, digestion, and sensation. The mechanisms and spatiotemporal control of TGR5 signaling are poorly understood. We investigated TGR5 signaling and trafficking in transfected HEK293 cells and colonocytes (NCM460) that endogenously express TGR5. BAs (deoxycholic acid (DCA), taurolithocholic acid) and the selective agonists oleanolic acid and 3-(2-chlorophenyl)-N-(4-chlorophenyl)-N, 5-dimethylisoxazole-4-carboxamide stimulated cAMP formation but did not induce TGR5 endocytosis or recruitment of β-arrestins, as assessed by confocal microscopy. DCA, taurolithocholic acid, and oleanolic acid did not stimulate TGR5 association with β-arrestin 1/2 or G protein-coupled receptor kinase (GRK) 2/5/6, as determined by bioluminescence resonance energy transfer. 3-(2-chlorophenyl)-N-(4-chlorophenyl)-N, 5-dimethylisoxazole-4-carboxamide stimulated a low level of TGR5 interaction with β-arrestin 2 and GRK2. DCA induced cAMP formation at the plasma membrane and cytosol, as determined using exchange factor directly regulated by cAMP (Epac2)-based reporters, but cAMP signals did not desensitize. AG1478, an inhibitor of epidermal growth factor receptor tyrosine kinase, the metalloprotease inhibitor batimastat, and methyl-β-cyclodextrin and filipin, which block lipid raft formation, prevented DCA stimulation of ERK1/2. Bioluminescence resonance energy transfer analysis revealed TGR5 and EGFR interactions that were blocked by disruption of lipid rafts. DCA stimulated TGR5 redistribution to plasma membrane microdomains, as localized by immunogold electron microscopy. Thus, TGR5 does not interact with β-arrestins, desensitize, or traffic to endosomes. TGR5 signals from plasma membrane rafts that facilitate EGFR interaction and transactivation. An understanding of the spatiotemporal control of TGR5 signaling provides insights into the actions of BAs and therapeutic TGR5 agonists

  13. Aryl Hydrocarbon Receptor Promotes RORγt+ ILCs and Controls Intestinal Immunity and Inflammation

    PubMed Central

    Qiu, Ju; Zhou, Liang

    2013-01-01

    Unlike adaptive immune cells that require antigen recognition and functional maturation during infection, innate lymphoid cells (ILCs) usually respond to pathogens promptly and serve as the first line of defense in infectious diseases. RAR-related orphan receptors (RORγt)+ ILCs are one of the innate cell populations that have recently been intensively studied. During the fetal stage of development, RORγt+ ILCs (e.g., lymphoid tissue inducer-LTi cells) are required for lymphoid organogenesis. In adult mice, RORγt+ ILCs are abundantly present in the gut to exert immune defensive functions. Under certain circumstances, however, RORγt+ ILCs can be pathogenic and contribute to intestinal inflammation. Aryl hydrocarbon receptor (Ahr), a ligand-dependent transcriptional factor, is widely expressed by various immune and non-immune cells. In the gut, the ligand for Ahr can be derived/generated from diet, microflora, and/or host cells. Ahr has been shown to regulate different cell populations in the immune system including RORγt+ ILCs, T helper (Th)17/22 cells, γδT cells, regulatory T cells (Tregs), Tr1 cells, and antigen presenting cells (APCs). In this review, we will focus on the development and function of RORγt+ ILCs, and discuss the role of Ahr in intestinal immunity and inflammation in mice and in humans. Better understanding the function of Ahr in the gut is important for developing new therapeutic means to target Ahr in future treatment of infectious and autoimmune diseases. PMID:23975386

  14. Variant Ionotropic Receptors in the Malaria Vector Mosquito Anopheles gambiae Tuned to Amines and Carboxylic Acids

    PubMed Central

    Pitts, R. Jason; Derryberry, Stephen L.; Zhang, Zhiwei; Zwiebel, Laurence J.

    2017-01-01

    The principal Afrotropical human malaria vector mosquito, Anopheles gambiae, remains a significant threat to global health. A critical component in the transmission of malaria is the ability of An. gambiae females to detect and respond to human-derived chemical kairomones in their search for blood meal hosts. The basis for host odor responses resides in olfactory receptor neurons (ORNs) that express chemoreceptors encoded by large gene families, including the odorant receptors (ORs) and the variant ionotropic receptors (IRs). While ORs have been the focus of extensive investigation, functional IR complexes and the chemical compounds that activate them have not been identified in An. gambiae. Here we report the transcriptional profiles and functional characterization of three An. gambiae IR (AgIr) complexes that specifically respond to amines or carboxylic acids - two classes of semiochemicals that have been implicated in mediating host-seeking by adult females but are not known to activate An. gambiae ORs (AgOrs). Our results suggest that AgIrs play critical roles in the detection and behavioral responses to important classes of host odors that are underrepresented in the AgOr chemical space. PMID:28067294

  15. Quinolinic acid induces neuritogenesis in SH-SY5Y neuroblastoma cells independently of NMDA receptor activation.

    PubMed

    Hernandez-Martinez, Juan-Manuel; Forrest, Caroline M; Darlington, L Gail; Smith, Robert A; Stone, Trevor W

    2017-03-01

    Glutamate and nicotinamide adenine dinucleotide (NAD + ) have been implicated in neuronal development and several types of cancer. The kynurenine pathway of tryptophan metabolism includes quinolinic acid (QA) which is both a selective agonist at N-methyl-D-aspartate (NMDA) receptors and also a precursor for the formation of NAD + . The effect of QA on cell survival and differentiation has therefore been examined on SH-SY5Y human neuroblastoma cells. Retinoic acid (RA, 10 μm) induced differentiation of SH-SY5Y cells into a neuronal phenotype showing neurite growth. QA (50-150 nm) also caused a concentration-dependent increase in the neurite/soma ratio, indicating differentiation. Both RA and QA increased expression of the neuronal marker β3-tubulin in whole-cell homogenates and in the neuritic fraction assessed using a neurite outgrowth assay. Expression of the neuronal proliferation marker doublecortin revealed that, unlike RA, QA did not decrease the number of mitotic cells. QA-induced neuritogenesis coincided with an increase in the generation of reactive oxygen species. Neuritogenesis was prevented by diphenylene-iodonium (an inhibitor of NADPH oxidase) and superoxide dismutase, supporting the involvement of reactive oxygen species. NMDA itself did not promote neuritogenesis and the NMDA antagonist dizocilpine (MK-801) did not prevent quinolinate-induced neuritogenesis, indicating that the effects of QA were independent of NMDA receptors. Nicotinamide caused a significant increase in the neurite/soma ratio and the expression of β3-tubulin in the neuritic fraction. Taken together, these results suggest that QA induces neuritogenesis by promoting oxidizing conditions and affecting the availability of NAD + , independently of NMDA receptors. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  16. Human esophageal myofibroblasts secrete proinflammatory cytokines in response to acid and Toll-like receptor 4 ligands

    PubMed Central

    Gargus, Matthew; Niu, Chao; Vallone, John G.; Binkley, Jana; Rubin, Deborah C.

    2015-01-01

    The pathophysiology of esophageal injury, repair, and inflammation in gastroesophageal reflux-disease (GERD) is complex. Whereas most studies have focused on the epithelial response to GERD injury, we are interested in the stromal response. We hypothesized that subepithelial esophageal myofibroblasts in GERD secrete proinflammatory cytokines in response to injurious agents encountered via epithelial barrier breaches or through dilated epithelial intercellular spaces. We determined the percentage of myofibroblasts [α-smooth muscle actin (α-SMA)+vimentin+CD31−] in the subepithelial GERD and normal esophageal stroma by immunomorphologic analysis. We performed α-SMA coimmunostaining with IL-6 and p65. We established and characterized primary cultures of α-SMA+vimentin+CD31−CD45− human esophageal myofibroblasts (HuEso MFs). We modeled GERD by treatment with pH 4.5-acidified media and Toll-like receptor 4 (TLR4) ligands, LPS and high-mobility group box 1 protein (HMGB1), and determined myofibroblast cytokine secretion in response to GERD injury. We demonstrate that spindle-shaped cell myofibroblasts are located near the basement membrane of stratified squamous epithelium in normal esophagus. We identify an increase in subepithelial myofibroblasts and activation of proinflammatory pathways in patients with GERD. Primary cultures of stromal cells obtained from normal esophagus retain myofibroblast morphology and express the acid receptor transient receptor potential channel vanilloid subfamily 1 (TRPV1) and TLR4. HuEso MFs stimulated with acid and TLR4 agonists LPS and HMGB1 increase IL-6 and IL-8 secretion via TRPV1 and NF-κB activation. Our work implicates a role for human subepithelial stromal cells in the pathogenesis of GERD-related esophageal injury. Findings of this study can be extended to the investigation of epithelial-stromal interactions in inflammatory esophageal mucosal disorders. PMID:25882613

  17. Chlorogenic Acid Improves Late Diabetes through Adiponectin Receptor Signaling Pathways in db/db Mice

    PubMed Central

    Jin, Shasha; Chang, Cuiqing; Zhang, Lantao; Liu, Yang; Huang, Xianren; Chen, Zhimin

    2015-01-01

    The aim of this study was to examine the effects of chlorogenic acid (CGA) on glucose and lipid metabolism in late diabetic db/db mice, as well as on adiponectin receptors and their signaling molecules, to provide evidence for CGA in the prevention of type 2 diabetes. We randomly divided 16 female db/db mice into db/db-CGA and db/db-control (CON) groups equally; db/m mice were used as control mice. The mice in both the db/db-CGA and db/m-CGA groups were administered 80 mg/kg/d CGA by lavage for 12 weeks, whereas the mice in both CON groups were given equal volumes of phosphate-buffered saline (PBS) by lavage. At the end of the intervention, we assessed body fat and the parameters of glucose and lipid metabolism in the plasma, liver and skeletal muscle tissues as well as the levels of aldose reductase (AR) and transforming growth factor-β1 (TGF-β1) in the kidneys and measured adiponectin receptors and the protein expression of their signaling molecules in liver and muscle tissues. After 12 weeks of intervention, compared with the db/db-CON group, the percentage of body fat, fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c) in the db/db-CGA group were all significantly decreased; TGF-β1 protein expression and AR activity in the kidney were both decreased; and the adiponectin level in visceral adipose was increased. The protein expression of adiponectin receptors (ADPNRs), the phosphorylation of AMP-activated protein kinase (AMPK) in the liver and muscle, and the mRNA and protein levels of peroxisome proliferator-activated receptor alpha (PPAR-α) in the liver were all significantly greater. CGA could lower the levels of fasting plasma glucose and HbA1c during late diabetes and improve kidney fibrosis to some extent through the modulation of adiponectin receptor signaling pathways in db/db mice. PMID:25849026

  18. The nuclear bile acid receptor FXR controls the liver derived tumor suppressor histidine-rich glycoprotein.

    PubMed

    Deuschle, Ulrich; Birkel, Manfred; Hambruch, Eva; Hornberger, Martin; Kinzel, Olaf; Perović-Ottstadt, Sanja; Schulz, Andreas; Hahn, Ulrike; Burnet, Michael; Kremoser, Claus

    2015-06-01

    The nuclear bile acid receptor Farnesoid X receptor (FXR) is strongly expressed in liver and intestine, controls bile acid and lipid homeostasis and exerts tumor-protective functions in liver and intestine. Histidine-rich glycoprotein (HRG) is an abundant plasma protein produced by the liver with the proposed function as a pattern recognition molecule involved in the clearance of immune complexes, necrotic cells and pathogens, the modulation of angiogenesis, the normalization of deranged endothelial vessel structure in tumors and tumor suppression. FXR recognition sequences were identified within a human HRG promoter fragment that mediated FXR/FXR-agonist dependent reporter gene activity in vitro. We show that HRG is a novel transcriptional target gene of FXR in human hepatoma cells, human upcyte® primary hepatocytes and 3D human liver microtissues in vitro and in mouse liver in vivo. Prolonged administration of the potent nonsteroidal FXR agonist PX20606 increases HRG levels in mouse plasma. Finally, daily oral administration of this FXR agonist for seven days resulted in a significant increase of HRG levels in the plasma of healthy human male volunteers during a clinical Phase I safety study. HRG might serve as a surrogate marker indicative of liver-specific FXR activation in future human clinical studies. Furthermore, potent FXR agonists might be beneficial in serious health conditions where HRG is reduced, for example, in hepatocellular carcinoma but also other solid cancers, liver failure, sepsis and pre-eclampsia. © 2014 UICC.

  19. Tomato PYR/PYL/RCAR abscisic acid receptors show high expression in root, differential sensitivity to the abscisic acid agonist quinabactin, and the capability to enhance plant drought resistance.

    PubMed

    González-Guzmán, Miguel; Rodríguez, Lesia; Lorenzo-Orts, Laura; Pons, Clara; Sarrión-Perdigones, Alejandro; Fernández, Maria A; Peirats-Llobet, Marta; Forment, Javier; Moreno-Alvero, Maria; Cutler, Sean R; Albert, Armando; Granell, Antonio; Rodríguez, Pedro L

    2014-08-01

    Abscisic acid (ABA) plays a crucial role in the plant's response to both biotic and abiotic stress. Sustainable production of food faces several key challenges, particularly the generation of new varieties with improved water use efficiency and drought tolerance. Different studies have shown the potential applications of Arabidopsis PYR/PYL/RCAR ABA receptors to enhance plant drought resistance. Consequently the functional characterization of orthologous genes in crops holds promise for agriculture. The full set of tomato (Solanum lycopersicum) PYR/PYL/RCAR ABA receptors have been identified here. From the 15 putative tomato ABA receptors, 14 of them could be grouped in three subfamilies that correlated well with corresponding Arabidopsis subfamilies. High levels of expression of PYR/PYL/RCAR genes was found in tomato root, and some genes showed predominant expression in leaf and fruit tissues. Functional characterization of tomato receptors was performed through interaction assays with Arabidopsis and tomato clade A protein phosphatase type 2Cs (PP2Cs) as well as phosphatase inhibition studies. Tomato receptors were able to inhibit the activity of clade A PP2Cs differentially in an ABA-dependent manner, and at least three receptors were sensitive to the ABA agonist quinabactin, which inhibited tomato seed germination. Indeed, the chemical activation of ABA signalling induced by quinabactin was able to activate stress-responsive genes. Both dimeric and monomeric tomato receptors were functional in Arabidopsis plant cells, but only overexpression of monomeric-type receptors conferred enhanced drought resistance. In summary, gene expression analyses, and chemical and transgenic approaches revealed distinct properties of tomato PYR/PYL/RCAR ABA receptors that might have biotechnological implications. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  20. Decreased agonist sensitivity of human GABA(A) receptors by an amino acid variant, isoleucine to valine, in the alpha1 subunit.

    PubMed

    Westh-Hansen, S E; Rasmussen, P B; Hastrup, S; Nabekura, J; Noguchi, K; Akaike, N; Witt, M R; Nielsen, M

    1997-06-25

    Recombinant human GABA(A) receptors were investigated in vitro by coexpression of cDNAs coding for alpha1, beta2, and gamma2 subunits in the baculovirus/Sf-9 insect cell system. We report that a single amino acid exchange (isoleucine 121 to valine 121) in the N-terminal, extracellular part of the alpha1 subunit induces a marked decrease in agonist GABA(A) receptor ligand sensitivity. The potency of muscimol and GABA to inhibit the binding of the GABA(A) receptor antagonist [3H]SR 95531 (2-(3-carboxypropyl)-3-amino-6-(4-methoxyphenyl)pyridazinium bromide) was higher in receptor complexes of alpha1(ile 121) beta2gamma2 than in those of alpha1(val 121) beta2gamma2 (IC50 values were 32-fold and 26-fold lower for muscimol and GABA, respectively). The apparent affinity of the GABA(A) receptor antagonist bicuculline methiodide to inhibit the binding of [3H]SR 95531 did not differ between the two receptor complex variants. Electrophysiological measurements of GABA induced whole-cell Cl- currents showed a ten-fold decrease in the GABA(A) receptor sensitivity of alpha1 (val 121) beta2gamma2 as compared to alpha1(ile 121) beta2gamma2 receptor complexes. Thus, a relatively small change in the primary structure of the alpha1 subunit leads to a decrease selective for GABA(A) receptor sensitivity to agonist ligands, since no changes were observed in a GABA(A) receptor antagonist affinity and benzodiazepine receptor binding.

  1. Immunization against exon 1 decapeptides from the lutropin/choriogonadotropin receptor or the follitropin receptor as potential male contraceptive.

    PubMed

    Remy, J J; Couture, L; Rabesona, H; Haertle, T; Salesse, R

    1996-11-01

    Pituitary gonadotropin hormones lutropin (LH) and follitropin (FSH) control steroidogenesis and gametogenesis in male and female gonads through interaction with G protein-coupled receptors, LHR and FSHR. In the male, LH acts on leydig cells and is mostly responsible for the acquisition of puberty and the production of androgens while FSH, together with androgens, regulates spermatogenesis within Sertoli cells. We have engineered filamentous phages displaying mouse LHR and human FSHR decapeptides chosen in hormone binding regions. Peptides from both receptors displayed on phages belong either to the receptor specific exon 1 (amino acids 18-27) or to the homologous exon 4 (amino acids 98-107). Vaccination of prepubertal BALB/c male mice with hybrid phages using sub-cutaneous or intraperitoneal injections induced immunity against receptors. Anti-receptor immunization produced agonist or antagonist effects depending only on the circulating levels of the antibodies. Both anti-LHR and anti-FSHR vaccines induced efficient as well as reversible male contraception, through different mechanisms: targeting LH receptors inhibited or hyperstimulated Leydig cell testosterone production while targeting FSH receptors did not affect testosterone levels.

  2. Adolescent social defeat alters N-methyl-D-aspartic acid receptor expression and impairs fear learning in adulthood.

    PubMed

    Novick, Andrew M; Mears, Mackenzie; Forster, Gina L; Lei, Yanlin; Tejani-Butt, Shanaz M; Watt, Michael J

    2016-05-01

    Repeated social defeat of adolescent male rats results in adult mesocortical dopamine hypofunction, impaired working memory, and increased contextual anxiety-like behavior. Given the role of glutamate in dopamine regulation, cognition, and fear and anxiety, we investigated potential changes to N-methyl-D-aspartic acid (NMDA) receptors following adolescent social defeat. As both NMDA receptors and mesocortical dopamine are implicated in the expression and extinction of conditioned fear, a separate cohort of rats was challenged with a classical fear conditioning paradigm to investigate whether fear learning is altered by adolescent defeat. Quantitative autoradiography was used to measure 3H-MK-801 binding to NMDA receptors in regions of the medial prefrontal cortex, caudate putamen, nucleus accumbens, amygdala and hippocampus. Assessment of fear learning was achieved using an auditory fear conditioning paradigm, with freezing toward the auditory tone used as a measure of conditioned fear. Compared to controls, adolescent social defeat decreased adult NMDA receptor expression in the infralimbic region of the prefrontal cortex and central amygdala, while increasing expression in the CA3 region of the hippocampus. Previously defeated rats also displayed decreased conditioned freezing during the recall and first extinction periods, which may be related to the observed decreases and increases in NMDA receptors within the central amygdala and CA3, respectively. The alteration in NMDA receptors seen following adolescent social defeat suggests that dysfunction of glutamatergic systems, combined with mesocortical dopamine deficits, likely plays a role in the some of the long-term behavioral consequences of social stressors in adolescence seen in both preclinical and clinical studies. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Free fatty acid receptor 3 is a key target of short chain fatty acid. What is the impact on the sympathetic nervous system?

    PubMed

    López Soto, Eduardo Javier; Gambino, Luisina Ongaro; Mustafá, Emilio Román

    2014-01-01

    Nervous system (NS) activity participates in metabolic homeostasis by detecting peripheral signal molecules derived from food intake and energy balance. High quality diets are thought to include fiber-rich foods like whole grain rice, breads, cereals, and grains. Several studies have associated high consumption of fiber-enriched diets with a reduced risk of diabetes, obesity, and gastrointestinal disorders. In the lower intestine, anaerobic fermentation of soluble fibers by microbiota produces short chain fatty acids (SCFAs), key energy molecules that have a recent identified leading role in the intestinal gluconeogenesis, promoting beneficial effects on glucose tolerance and insulin resistance. SCFAs are also signaling molecules that bind to specific G-protein coupled receptors (GPCRs) named Free Fatty Acid Receptor 3 (FFA3, GPR41) and 2 (FFA2, GPR43). However, how SCFAs impact NS activity through their GPCRs is poorly understood. Recently, studies have demonstrated the presence of FFA2 and FFA3 in the sympathetic NS of rat, mouse and human. Two studies have showed that FFA3 activation by SCFAs increases firing and norepinephrine (NE) release from sympathetic neurons. However, the recent study from the Ikeda Laboratory revealed that activation of FFA3 by SCFAs impairs N-type calcium channel (NTCC) activity, which contradicts the idea of FFA3 activation leading to increased action potential evoked NE release. Here we will discuss the scope of the latter study and the putative physiological role of SCFAs and FFAs in the sympathetic NS.

  4. ATP7A is a novel target of retinoic acid receptor β2 in neuroblastoma cells

    PubMed Central

    Bohlken, A; Cheung, B B; Bell, J L; Koach, J; Smith, S; Sekyere, E; Thomas, W; Norris, M; Haber, M; Lovejoy, D B; Richardson, D R; Marshall, G M

    2009-01-01

    Increased retinoic acid receptor β (RARβ2) gene expression is a hallmark of cancer cell responsiveness to retinoid anticancer effects. Moreover, low basal or induced RARβ2 expression is a common feature of many human cancers, suggesting that RARβ2 may act as a tumour suppressor gene in the absence of supplemented retinoid. We have previously shown that low RARβ2 expression is a feature of advanced neuroblastoma. Here, we demonstrate that the ABC domain of the RARβ2 protein alone was sufficient for the growth inhibitory effects of RARβ2 on neuroblastoma cells. ATP7A, the copper efflux pump, is a retinoid-responsive gene, was upregulated by ectopic overexpression of RARβ2. The ectopic overexpression of the RARβ2 ABC domain was sufficient to induce ATP7A expression, whereas, RARβ2 siRNA blocked the induction of ATP7A expression in retinoid-treated neuroblastoma cells. Forced downregulation of ATP7A reduced copper efflux and increased viability of retinoid-treated neuroblastoma cells. Copper supplementation enhanced cell growth and reduced retinoid-responsiveness, whereas copper chelation reduced the viability and proliferative capacity. Taken together, our data demonstrates ATP7A expression is regulated by retinoic acid receptor β and it has effects on intracellular copper levels, revealing a link between the anticancer action of retinoids and copper metabolism. PMID:19127267

  5. The Distribution of Charged Amino Acid Residues and the Ca2+ Permeability of Nicotinic Acetylcholine Receptors: A Predictive Model.

    PubMed

    Fucile, Sergio

    2017-01-01

    Nicotinic acetylcholine receptors (nAChRs) are cation-selective ligand-gated ion channels exhibiting variable Ca 2+ permeability depending on their subunit composition. The Ca 2+ permeability is a crucial functional parameter to understand the physiological role of nAChRs, in particular considering their ability to modulate Ca 2+ -dependent processes such as neurotransmitter release. The rings of extracellular and intracellular charged amino acid residues adjacent to the pore-lining TM2 transmembrane segment have been shown to play a key role in the cation selectivity of these receptor channels, but to date a quantitative relationship between these structural determinants and the Ca 2+ permeability of nAChRs is lacking. In the last years the Ca 2+ permeability of several nAChR subtypes has been experimentally evaluated, in terms of fractional Ca 2+ current ( Pf , i.e., the percentage of the total current carried by Ca 2+ ions). In the present study, the available Pf -values of nAChRs are used to build a simplified modular model describing the contribution of the charged residues in defined regions flanking TM2 to the selectivity filter controlling Ca 2+ influx. This model allows to predict the currently unknown Pf -values of existing nAChRs, as well as the hypothetical Ca 2+ permeability of subunit combinations not able to assemble into functional receptors. In particular, basing on the amino acid sequences, a Pf > 50% would be associated with homomeric nAChRs composed by different α subunits, excluding α7, α9, and α10. Furthermore, according to the model, human α7β2 receptors should have Pf -values ranging from 3.6% (4:1 ratio) to 0.1% (1:4 ratio), much lower than the 11.4% of homomeric α7 nAChR. These results help to understand the evolution and the function of the large diversity of the nicotinic receptor family.

  6. Similarities and differences between the responses induced in human phagocytes through activation of the medium chain fatty acid receptor GPR84 and the short chain fatty acid receptor FFA2R.

    PubMed

    Sundqvist, Martina; Christenson, Karin; Holdfeldt, André; Gabl, Michael; Mårtensson, Jonas; Björkman, Lena; Dieckmann, Regis; Dahlgren, Claes; Forsman, Huamei

    2018-05-01

    GPR84 is a recently de-orphanized member of the G-protein coupled receptor (GPCR) family recognizing medium chain fatty acids, and has been suggested to play important roles in inflammation. Due to the lack of potent and selective GPR84 ligands, the basic knowledge related to GPR84 functions is very limited. In this study, we have characterized the GPR84 activation profile and regulation mechanism in human phagocytes, using two recently developed small molecules that specifically target GPR84 agonistically (ZQ16) and antagonistically (GLPG1205), respectively. Compared to our earlier characterization of the short chain fatty acid receptor FFA2R which is functionally expressed in neutrophils but not in monocytes, GPR84 is expressed in both cell types and in monocyte-derived macrophages. In neutrophils, the GPR84 agonist had an activation profile very similar to that of FFA2R. The GPR84-mediated superoxide release was low in naïve cells, but the response could be significantly primed by TNFα and by the actin cytoskeleton disrupting agent Latrunculin A. Similar to that of FFA2R, a desensitization mechanism bypassing the actin cytoskeleton was utilized by GPR84. All ZQ16-mediated cellular responses were sensitive to GLPG1205, confirming the GPR84-dependency. Finally, our data of in vivo transmigrated tissue neutrophils indicate that both GPR84 and FFA2R are involved in neutrophil recruitment processes in vivo. In summary, we show functional similarities but also some important differences between GPR84 and FFA2R in human phagocytes, thus providing some mechanistic insights into GPR84 regulation in blood neutrophils and cells recruited to an aseptic inflammatory site in vivo. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Discovery of a new class of ionotropic glutamate receptor antagonists by the rational design of (2S,3R)-3-(3-carboxyphenyl)-pyrrolidine-2-carboxylic acid.

    PubMed

    Larsen, Ann M; Venskutonytė, Raminta; Valadés, Elena Antón; Nielsen, Birgitte; Pickering, Darryl S; Bunch, Lennart

    2011-02-16

    The kainic acid (KA) receptors belong to the class of glutamate (Glu) receptors in the brain and constitute a promising target for the treatment of neurological and/or psychiatric diseases such as schizophrenia, major depression, and epilepsy. Five KA subtypes have been identified and named GluK1-5. In this article, we present the discovery of (2S,3R)-3-(3-carboxyphenyl)-pyrrolidine-2-carboxylic acid (1) based on a rational design process. Target compound 1 was synthesized by a stereoselective strategy in 10 steps from commercially available starting materials. Binding affinities of 1 at native ionotropic Glu receptors were determined to be in the micromolar range (AMPA, 51 μM; KA, 22 μM; NMDA 6 μM), with the highest affinity for cloned homomeric KA receptor subtypes GluK1,3 (3.0 and 8.1 μM, respectively). Functional characterization of 1 by two electrode voltage clamp (TEVC) electrophysiology at a nondesensitizing mutant of GluK1 showed full competitive antagonistic behavior with a K(b) of 11.4 μM.

  8. ACTIVATION OF MOUSE AND HUMAN PEROXISOME PROLIFERATOR-ACTIVATED RECEPTORS (PPAR ALPHA, GAMMA, BETA DELTA) BY PERFLUOROOCTANOIC ACID (PFOA) AND PERFLUOROOCTANE SULFONATE (PFOS)

    EPA Science Inventory

    This study evaluates the potential for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) to activate peroxisome proliferator-activated receptors (PPARs), using a transient transfection cell assay. Cos-1 cells were cultured in DMEM with fetal bovine serum (FBS) in ...

  9. Gintonin enhances performance of mice in rotarod test: Involvement of lysophosphatidic acid receptors and catecholamine release.

    PubMed

    Lee, Byung-Hwan; Kim, Jisu; Lee, Ra Mi; Choi, Sun-Hye; Kim, Hyeon-Joong; Hwang, Sung-Hee; Lee, Myung Koo; Bae, Chun-Sik; Kim, Hyoung-Chun; Rhim, Hyewon; Lim, Kiwon; Nah, Seung-Yeol

    2016-01-26

    Ginseng has a long history of use as a tonic for restoration of vigor. One example of ginseng-derived tonic effect is that it can improve physical stamina under conditions of stress. However, the active ingredient and the underlying molecular mechanism responsible for the ergogenic effect are unknown. Recent studies show that ginseng contains a novel ingredient, gintonin, which consists of a unique class of herbal-medicine lysophosphatidic acids (LPAs). Gintonin activates G protein-coupled LPA receptors to produce a transient [Ca(2+)]i signal, which is coupled to diverse intra- and inter-cellular signal transduction pathways that stimulate hormone or neurotransmitter release. However, relatively little is known about how gintonin-mediated cellular modulation is linked to physical endurance. In the present study, systemic administration of gintonin, but not ginsenosides, in fasted mice increased blood glucose concentrations in a dose-dependent manner. Gintonin treatment elevated blood glucose to a maximum level after 30min. This elevation in blood glucose level could be abrogated by the LPA1/3 receptor antagonist, Ki16425, or the β-adrenergic receptor antagonist, propranolol. Furthermore, gintonin-dependent enhanced performance of fasted mice in rotarod test was likewise abrogated by Ki16425. Gintonin also elevated plasma epinephrine and norepinephrine concentrations. The present study shows that gintonin mediates catecholamine release through activation of the LPA receptor and that activation of the β-adrenergic receptor is coupled to liver glycogenolysis, thereby increasing the supply of glucose and enhancing performance in the rotarod test. Thus, gintonin acts via the LPA-catecholamine-glycogenolysis axis, representing a candidate mechanism that can explain how ginseng treatment enhances physical stamina. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  10. Functional Roles of Pattern Recognition Receptors That Recognize Virus Nucleic Acids in Human Adipose-Derived Mesenchymal Stem Cells

    PubMed Central

    Wang, Fangchao; Yang, Can; Liu, Guoyan; Song, Xiangfeng

    2016-01-01

    Human adipose-derived mesenchymal stem cells (hAD-MSCs) are mesenchymal stem cells with the capability to modulate immune responses. Evidence showing that hAD-MSCs could mediate innate immune responses through pattern recognition receptors (PRRs) is increasing. However, the roles of PRRs in regulating the innate sensing of virus nucleic acids (RNA and DNA) in hAD-MSCs have not yet been investigated. This study focused on the abundant expression of PRRs, including Toll-like receptor 3 (TLR3) and retinoic acid-inducible gene I (RIG-I), which recognize viral RNA, and gamma-interferon inducible protein 16 (IFI16), which recognizes viral DNA in hAD-MSCs. Poly(I:C), a synthetic dsRNA analogy, activated TLR3 and RIG-I and induced the expression of type I interferons (IFN-α/β) and antivirus proteins, including IFN-stimulating gene 15, 2′5′-oligoadenylate synthetase, and Mx GTPase 1 in hAD-MSCs, which were attenuated by the knockdown of each TLR3 or RIG-I. Synthetic herpes simplex viral DNA (HSV60) activated IFI16 and induced the expression of IFN-α/β and antivirus proteins in hAD-MSCs, which were inhibited by the knockdown of IFI16. Both poly(I:C) and HSV60 induced the expression of IFN-α/β through the phosphorylation of IFN-regulatory factor 3. All these results indicated that PRRs recognizing virus nucleic acids were expressed and can mediate antivirus responses in hAD-MSCs. PMID:28105439

  11. Ionotropic and metabotropic receptor mediated airway sensory nerve activation.

    PubMed

    Lee, Min-Goo; Kollarik, Marian; Chuaychoo, Benjamas; Undem, Bradley J

    2004-01-01

    There are several receptors capable of inducing activating generator potentials in cough-associated afferent terminals in the airways. The chemical receptors leading to generator potentials can be subclassified into ionotropic and metabotropic types. An ionotropic receptor has an agonist-binding domain, and also serves directly as an ion channel that is opened upon binding of the agonist. Examples of ionotropic receptors found in airway sensory nerve terminals include receptors for serotonin (5-HT3 receptors), ATP (P2X receptors), acetylcholine (nicotinic receptors), receptors for capsaicin and related vanilloids (TRPV1 receptors), and acid receptors (acid sensing ion channels). Afferent nerve terminals can also be depolarized via activation of metabotropic or G-protein coupled receptors (GPCRs). Among the GPCRs that can lead to activation of airway afferent fibers include bradykinin B2 and adenosine A1 receptors. The signaling events leading to GPCR-mediated membrane depolarization are more complex than that seen with ionotropic receptors. The GPCR-mediated effects are thought to occur through classical second messenger systems such as activation of phospholipase C. This may lead to membrane depolarization through interaction with specific ionotropic receptors (such as TRPV1) and/or various types of calcium activated channels.

  12. Structure-activity relationships of seco-prezizaane terpenoids in gamma-aminobutyric acid receptors of houseflies and rats.

    PubMed

    Kuriyama, Tadahiko; Schmidt, Thomas J; Okuyama, Emi; Ozoe, Yoshihisa

    2002-06-01

    Thirteen seco-prezizaane terpenoids isolated from star anise species (Illcium floridanum, Illcium parviflorum, and Illcium verum) were investigated for their ability to inhibit the specific binding of [(3)H]4'-ethynyl-4-n-propylbicycloorthobenzoate (EBOB), a non-competitive antagonist of gamma-aminobutyric acid (GABA) receptors, to housefly-head and rat-brain membranes. Veranisatin A was found to be the most potent inhibitor in both membranes, with an IC(50)(fly) of 78.5 nM and an IC(50)(rat) of 271 nM, followed by anisatin (IC(50)(fly)=123 nM; IC(50)(rat)=282 nM). Six of the other 11 tested compounds were effective only in housefly-head membranes. Pseudoanisatin proved to display a high (>26-fold) selectivity for housefly versus rat GABA receptors (IC(50)(fly)=376 nM; IC(50)(rat) >10,000 nM). Although pseudoanisatin does not structurally resemble EBOB, Scatchard plots indicated that the two compounds bind to the same site in housefly receptors. Anisatin and pseudoanisatin exhibited moderate insecticidal activity against German cockroaches. Comparative molecular field analysis (CoMFA), a method of three-dimensional quantitative structure-activity relationship (3D-QSAR) analysis, demonstrated that seco-prezizaane terpenoids can bind to the same site as do picrotoxane terpenoids such as picrotoxinin and picrodendrins, and the CoMFA maps allowed us to identify the parts of the molecules essential to high activity in housefly GABA receptors.

  13. Solubilization of active opiate receptors.

    PubMed Central

    Simonds, W F; Koski, G; Streaty, R A; Hjelmeland, L M; Klee, W A

    1980-01-01

    Receptors that reversibly bind opiates and opioid peptides have been solubilized from brain and neuroblastoma-glioma hybrid cell NG108-15 membranes. Active receptors are specifically solubilized with a new type of detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, which is a zwitterionic derivative of cholic acid. The solubilized receptor complexes behave as large molecules with a Stokes radius of 70 A and contain protein as an essential constituent. PMID:6254034

  14. Retinoic acid receptor-related orphan receptor α stimulates adipose tissue inflammation by modulating endoplasmic reticulum stress.

    PubMed

    Liu, Yin; Chen, Yulong; Zhang, Jinlong; Liu, Yulan; Zhang, Yanjie; Su, Zhiguang

    2017-08-25

    Adipose tissue inflammation has been linked to metabolic diseases such as obesity and type 2 diabetes. However, the molecules that mediate inflammation in adipose tissue have not been addressed. Although retinoic acid receptor-related orphan receptor α (RORα) is known to be involved in the regulation of inflammatory response in some tissues, its role is largely unknown in adipose tissue. Conversely, it is known that endoplasmic reticulum (ER) stress and unfolding protein response (UPR) signaling affect the inflammatory response in obese adipose tissue, but whether RORα regulates these processes remains unknown. In this study, we investigate the link between RORα and adipose tissue inflammation. We showed that the inflammatory response in macrophages or 3T3-L1 adipocytes stimulated by lipopolysaccharide, as well as adipose tissue in obese mice, markedly increased the expression of RORα. Adenovirus-mediated overexpression of RORα or treatment with the RORα-specific agonist SR1078 enhanced the expression of inflammatory cytokines and increased the number of infiltrated macrophages into adipose tissue. Furthermore, SR1078 up-regulated the mRNA expression of ER stress response genes and enhanced phosphorylations of two of the three mediators of major UPR signaling pathways, PERK and IRE1α. Finally, we found that alleviation of ER stress using a chemical chaperone followed by the suppression of RORα induced inflammation in adipose tissue. Our data suggest that RORα-induced ER stress response potentially contributes to the adipose tissue inflammation that can be mitigated by treatment with chemical chaperones. The relationships established here between RORα expression, inflammation, and UPR signaling may have implications for therapeutic targeting of obesity-related metabolic diseases. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Isotretinoin and FoxO1

    PubMed Central

    2011-01-01

    Oral isotretinoin (13-cis retinoic acid) is the most effective drug in the treatment of acne and restores all major pathogenetic factors of acne vulgaris. isotretinoin is regarded as a prodrug which after isomerizisation to all-trans-retinoic acid (ATRA) induces apoptosis in cells cultured from human sebaceous glands, meibomian glands, neuroblastoma cells, hypothalamic cells, hippocampus cells, Dalton's lymphoma ascites cells, B16F-10 melanoma cells, and neuronal crest cells and others. By means of translational research this paper provides substantial indirect evidence for isotretinoin's mode of action by upregulation of forkhead box class O (FoxO) transcription factors. FoxOs play a pivotal role in the regulation of androgen receptor transactivation, insulin/insulin like growth factor-1 (IGF-1)-signaling, peroxisome proliferator-activated receptor-γ (PPArγ)- and liver X receptor-α (LXrα)-mediated lipogenesis, β-catenin signaling, cell proliferation, apoptosis, reactive oxygene homeostasis, innate and acquired immunity, stem cell homeostasis, as well as anti-cancer effects. An accumulating body of evidence suggests that the therapeutic, adverse, teratogenic and chemopreventive effecs of isotretinoin are all mediated by upregulation of FoxO-mediated gene transcription. These FoxO-driven transcriptional changes of the second response of retinoic acid receptor (RAR)-mediated signaling counterbalance gene expression of acne due to increased growth factor signaling with downregulated nuclear FoxO proteins. The proposed isotretinoin→ATRA→RAR→FoxO interaction offers intriguing new insights into the mode of isotretinoin action and explains most therapeutic, adverse and teratogenic effects of isotretinoin in the treatment of acne by a common mode of FoxO-mediated transcriptional regulation. PMID:22110774

  16. Identification, characterization and leucocyte expression of Siglec-10, a novel human sialic acid-binding receptor.

    PubMed Central

    Munday, J; Kerr, S; Ni, J; Cornish, A L; Zhang, J Q; Nicoll, G; Floyd, H; Mattei, M G; Moore, P; Liu, D; Crocker, P R

    2001-01-01

    Here we characterize Siglec-10 as a new member of the Siglec family of sialic acid-binding Ig-like lectins. A full-length cDNA was isolated from a human spleen library and the corresponding gene identified. Siglec-10 is predicted to contain five extracellular Ig-like domains and a cytoplasmic tail containing three putative tyrosine-based signalling motifs. Siglec-10 exhibited a high degree of sequence similarity to CD33-related Siglecs and mapped to the same region, on chromosome 19q13.3. The expressed protein was able to mediate sialic acid-dependent binding to human erythrocytes and soluble sialoglycoconjugates. Using specific antibodies, Siglec-10 was detected on subsets of human leucocytes including eosinophils, monocytes and a minor population of natural killer-like cells. The molecular properties and expression pattern suggest that Siglec-10 may function as an inhibitory receptor within the innate immune system. PMID:11284738

  17. Inhibitory effects of omega-3 fatty acids on injury-induced epidermal growth factor receptor transactivation contribute to delayed wound healing

    PubMed Central

    Turk, Harmony F.; Monk, Jennifer M.; Fan, Yang-Yi; Callaway, Evelyn S.; Weeks, Brad

    2013-01-01

    Epidermal growth factor receptor (EGFR)-mediated signaling is required for optimal intestinal wound healing. Since n-3 polyunsaturated fatty acids (PUFA), specifically docosahexaenoic acid (DHA), alter EGFR signaling and suppress downstream activation of key signaling pathways, we hypothesized that DHA would be detrimental to the process of intestinal wound healing. Using a mouse immortalized colonocyte model, DHA uniquely reduced EGFR ligand-induced receptor activation, whereas DHA and its metabolic precursor eicosapentaenoic acid (EPA) reduced wound-induced EGFR transactivation compared with control (no fatty acid or linoleic acid). Under wounding conditions, the suppression of EGFR activation was associated with a reduction in downstream activation of cytoskeletal remodeling proteins (PLCγ1, Rac1, and Cdc42). Subsequently, DHA and EPA reduced cell migration in response to wounding. Mice were fed a corn oil-, DHA-, or EPA-enriched diet prior to intestinal wounding (2.5% dextran sodium sulfate for 5 days followed by termination after 0, 3, or 6 days of recovery). Mortality was increased in EPA-fed mice and colonic histological injury scores were increased in EPA- and DHA-fed mice compared with corn oil-fed (control) mice. Although kinetics of colonic EGFR activation and downstream signaling (PLCγ1, Rac1, and Cdc42) were delayed by both n-3 PUFA, colonic repair was increased in EPA- relative to DHA-fed mice. These results indicate that, during the early response to intestinal wounding, DHA and EPA uniquely delay the activation of key wound-healing processes in the colon. This effect is mediated, at least in part, via suppression of EGFR-mediated signaling and downstream cytoskeletal remodeling. PMID:23426968

  18. An Allosteric Coagonist Model for Propofol Effects on α1β2γ2L γ-Aminobutyric Acid Type A Receptors

    PubMed Central

    Ruesch, Dirk; Neumann, Elena; Wulf, Hinnerk; Forman, Stuart A.

    2011-01-01

    Background Propofol produces its major actions via γ-aminobutyric acid type A (GABAA) receptors. At low concentrations, propofol enhances agonist-stimulated GABAA receptor activity, and high propofol concentrations directly activate receptors. Etomidate produces similar effects, and there is convincing evidence that a single class of etomidate sites mediate both agonist modulation and direct GABAA receptor activation. It is unknown if the propofol binding site(s) on GABAA receptors that modulate agonist-induced activity also mediate direct activation. Methods GABAA α1β2γ2L receptors were heterologously expressed in Xenopus oocytes and activity was quantified using voltage clamp electrophysiology. We tested whether propofol and etomidate display the same linkage between agonist modulation and direct activation of GABAA receptors by identifying equi-efficacious drug solutions for direct activation. We then determined whether these drug solutions produce equal modulation of GABA-induced receptor activity. We also measured propofol-dependent direct activation and modulation of low GABA responses. Allosteric coagonist models similar to that established for etomidate, but with variable numbers of propofol sites, were fitted to combined data. Results Solutions of 19 μM propofol and 10 μM etomidate were found to equally activate GABAA receptors. These two drug solutions also produced indistinguishable modulation of GABA-induced receptor activity. Combined electrophysiological data behaved in a manner consistent with allosteric co-agonist models with more than one propofol site. The best fit was observed when the model assumed three equivalent propofol sites. Conclusions Our results support the hypothesis that propofol, like etomidate, acts at GABAA receptor sites mediating both GABA modulation and direct activation. PMID:22104494

  19. The effects of dietary fatty acids on the postprandial triglyceride-rich lipoprotein/apoB48 receptor axis in human monocyte/macrophage cells.

    PubMed

    Varela, Lourdes M; Ortega-Gomez, Almudena; Lopez, Sergio; Abia, Rocio; Muriana, Francisco J G; Bermudez, Beatriz

    2013-12-01

    Intestinally produced triglyceride-rich lipoproteins (TRL) play an important role in the progression of atherosclerosis. In this study, we investigated the relevance of monounsaturated fatty acid (MUFA) and saturated fatty acid (SFA) in postprandial TRL in affecting the transcriptional activity of the apolipoprotein-B48 receptor (ApoB48R) and its functionality in human monocyte/macrophage cells. Healthy male volunteers were administered four standardized high-fat meals containing butter, high-palmitic sunflower oil, olive oil (ROO) or a mixture of vegetable and fish oils (50 g/m(2) body surface area) to obtain a panel of postprandial TRL with gradual MUFA oleic acid-to-SFA palmitic acid ratios. The increase in this ratio was linearly associated with a decrease of ApoB48R up-regulation and lipid accumulation in THP-1 and primary monocytes. ApoB48R mRNA levels and intracellular triglycerides were also lower in the monocytes from volunteers after the ingestion of the ROO meal when compared to the ingestion of the butter meal. In THP-1 macrophages, the increase in the MUFA oleic acid-to-SFA palmitic acid ratio in the postprandial TRL was linearly correlated with an increase in ApoB48R down-regulation and a decrease in lipid accumulation. We also revealed that the nuclear receptor transcription factors PPARα, PPARβ/δ, and PPARγ and the PPAR-RXR transcriptional complex were involved in sensing the proportion of MUFA oleic acid and SFA palmitic acid, and these were also involved in adjusting the transcriptional activity of ApoB48R. The results of this study support the notion that MUFA-rich dietary fats may prevent excessive lipid accumulation in monocyte/macrophage cells by targeting the postprandial TRL/ApoB48R axis. © 2013.

  20. Modulation of ATP-induced inward currents by docosahexaenoic acid and other fatty acids in rat nodose ganglion neurons.

    PubMed

    Eto, Kei; Arimura, Yukiko; Mizuguchi, Hiroko; Nishikawa, Masazumi; Noda, Mami; Ishibashi, Hitoshi

    2006-11-01

    The effects of docosahexaenoic acid (DHA) and other fatty acids on P2X-receptor-mediated inward currents in rat nodose ganglion neurons were studied using the nystatin perforated patch-clamp technique. DHA accelerated the desensitization rate of the ATP-induced current. DHA showed use-dependent inhibition of the peak ATP-induced current. Other polyunsaturated fatty acids, such as arachidonic acid and eicosapentaenoic acid, displayed a similar use-dependent inhibition. The inhibitory effects of saturated fatty acids including palmitic acid and arachidic acid were weaker than those of polyunsaturated fatty acids. The results suggest that fatty acids may modulate the P2X receptor-mediated response when the channel is in the open-state.

  1. Excitatory Amino Acids as Transmitters in the Brain

    DTIC Science & Technology

    1989-04-30

    Amino Acids as Transmitters in the Brain 12 PERSONAL AUTHOR(S) Cotman, C.W. 13a TYPE OF REPORT 1i3b TIME OYERED 14. DATE OF REPORT (Ye, Month, Day) 5s...necenearia i dentf by block number) FIEL.D GROUP SBGOP Excitatory receptors, excitatory amino acids , excitotoxicit N-methyl-D-aspartate, kainate...mediated by excitatory amino acids and their receptors. These receptors participate in both standard synaptic transmission as well as higher order

  2. Functionally important amino acid residues in the transient receptor potential vanilloid 1 (TRPV1) ion channel – an overview of the current mutational data

    PubMed Central

    2013-01-01

    This review aims to create an overview of the currently available results of site-directed mutagenesis studies on transient receptor potential vanilloid type 1 (TRPV1) receptor. Systematization of the vast number of data on the functionally important amino acid mutations of TRPV1 may provide a clearer picture of this field, and may promote a better understanding of the relationship between the structure and function of TRPV1. The review summarizes information on 112 unique mutated sites along the TRPV1, exchanged to multiple different residues in many cases. These mutations influence the effect or binding of different agonists, antagonists, and channel blockers, alter the responsiveness to heat, acid, and voltage dependence, affect the channel pore characteristics, and influence the regulation of the receptor function by phosphorylation, glycosylation, calmodulin, PIP2, ATP, and lipid binding. The main goal of this paper is to publish the above mentioned data in a form that facilitates in silico molecular modelling of the receptor by promoting easier establishment of boundary conditions. The better understanding of the structure-function relationship of TRPV1 may promote discovery of new, promising, more effective and safe drugs for treatment of neurogenic inflammation and pain-related diseases and may offer new opportunities for therapeutic interventions. PMID:23800232

  3. Synaptic Neurotransmitter-Gated Receptors

    PubMed Central

    Smart, Trevor G.; Paoletti, Pierre

    2012-01-01

    Since the discovery of the major excitatory and inhibitory neurotransmitters and their receptors in the brain, many have deliberated over their likely structures and how these may relate to function. This was initially satisfied by the determination of the first amino acid sequences of the Cys-loop receptors that recognized acetylcholine, serotonin, GABA, and glycine, followed later by similar determinations for the glutamate receptors, comprising non-NMDA and NMDA subtypes. The last decade has seen a rapid advance resulting in the first structures of Cys-loop receptors, related bacterial and molluscan homologs, and glutamate receptors, determined down to atomic resolution. This now provides a basis for determining not just the complete structures of these important receptor classes, but also for understanding how various domains and residues interact during agonist binding, receptor activation, and channel opening, including allosteric modulation. This article reviews our current understanding of these mechanisms for the Cys-loop and glutamate receptor families. PMID:22233560

  4. Role of a Ubiquitously Expressed Receptor in the Vertebrate Olfactory System

    PubMed Central

    DeMaria, Shannon; Berke, Allison P.; Van Name, Eric; Heravian, Anisa; Ferreira, Todd

    2013-01-01

    Odorant cues are recognized by receptors expressed on olfactory sensory neurons, the primary sensory neurons of the olfactory epithelium. Odorant receptors typically obey the “one receptor, one neuron” rule, in which the receptive field of the olfactory neuron is determined by the singular odorant receptor that it expresses. Odor-evoked receptor activity across the population of olfactory neurons is then interpreted by the brain to identify the molecular nature of the odorant stimulus. In the present study, we characterized the properties of a C family G-protein-coupled receptor that, unlike most other odorant receptors, is expressed in a large population of microvillous sensory neurons in the zebrafish olfactory epithelium and the mouse vomeronasal organ. We found that this receptor, OlfCc1 in zebrafish and its murine ortholog Vmn2r1, is a calcium-dependent, low-sensitivity receptor specific for the hydrophobic amino acids isoleucine, leucine, and valine. Loss-of-function experiments in zebrafish embryos demonstrate that OlfCc1 is required for olfactory responses to a diverse mixture of polar, nonpolar, acidic, and basic amino acids. OlfCc1 was also found to promote localization of other OlfC receptor family members to the plasma membrane in heterologous cells. Together, these results suggest that the broadly expressed OlfCc1 is required for amino acid detection by the olfactory system and suggest that it plays a role in the function and/or intracellular trafficking of other olfactory and vomeronasal receptors with which it is coexpressed. PMID:24048853

  5. Ferulic Acid Exerts Anti-Angiogenic and Anti-Tumor Activity by Targeting Fibroblast Growth Factor Receptor 1-Mediated Angiogenesis.

    PubMed

    Yang, Guang-Wei; Jiang, Jin-Song; Lu, Wei-Qin

    2015-10-12

    Most anti-angiogenic therapies currently being evaluated target the vascular endothelial growth factor (VEGF) pathway; however, the tumor vasculature can acquire resistance to VEGF-targeted therapy by shifting to other angiogenesis mechanisms. Therefore, other therapeutic agents that block non-VEGF angiogenic pathways need to be evaluated. Here, we identified ferulic acid as a novel fibroblast growth factor receptor 1 (FGFR1) inhibitor and a novel agent with potential anti-angiogenic and anti-cancer activities. Ferulic acid demonstrated inhibition of endothelial cell proliferation, migration and tube formation in response to basic fibroblast growth factor 1 (FGF1). In ex vivo and in vivo angiogenesis assays, ferulic acid suppressed FGF1-induced microvessel sprouting of rat aortic rings and angiogenesis. To understand the underlying molecular basis, we examined the effects of ferulic acid on different molecular components and found that ferulic acid suppressed FGF1-triggered activation of FGFR1 and phosphatidyl inositol 3-kinase (PI3K)-protein kinase B (Akt) signaling. Moreover, ferulic acid directly inhibited proliferation and blocked the PI3K-Akt pathway in melanoma cell. In vivo, using a melanoma xenograft model, ferulic acid showed growth-inhibitory activity associated with inhibition of angiogenesis. Taken together, our results indicate that ferulic acid targets the FGFR1-mediated PI3K-Akt signaling pathway, leading to the suppression of melanoma growth and angiogenesis.

  6. Nuclear Receptor Regulation of Aquaglyceroporins in Metabolic Organs.

    PubMed

    Tardelli, Matteo; Claudel, Thierry; Bruschi, Francesca Virginia; Trauner, Michael

    2018-06-15

    Nuclear receptors, such as the farnesoid X receptor (FXR) and the peroxisome proliferator-activated receptors gamma and alpha (PPAR-γ, -α), are major metabolic regulators in adipose tissue and the liver, where they govern lipid, glucose, and bile acid homeostasis, as well as inflammatory cascades. Glycerol and free fatty acids are the end products of lipid droplet catabolism driven by PPARs. Aquaporins (AQPs), a family of 13 small transmembrane proteins, facilitate the shuttling of water, urea, and/or glycerol. The peculiar role of AQPs in glycerol transport makes them pivotal targets in lipid metabolism, especially considering their tissue-specific regulation by the nuclear receptors PPARγ and PPARα. Here, we review the role of nuclear receptors in the regulation of glycerol shuttling in liver and adipose tissue through the function and expression of AQPs.

  7. PYRETHROID INSECTICIDES AND THE GAMMA-AMINOBUTYRIC ACID (ALPHA) RECEPTOR COMPLEX: MOTOR ACTIVITY AND THE ACOUSTIC STARTLE RESPONSE IN THE RAT (JOURNAL VERSION)

    EPA Science Inventory

    Two behavioral tests, locomotor activity and the acoustic startle response (ASR), were utilized to test for dose-addition of cismethrin, a Type I, or deltamethrin, a Type II pyrethroid, with compounds active to the gamma-aminobutryic acid (GABA) receptor complex (picrotoxin, musc...

  8. THE DEVELOPMENT OF AN IN VITRO ASSAY FOR EVALUATING THE BINDING OF PERFLUOROALKYL ACIDS (PFAAS) TO THE PEROXISOME PROLIFERATOR-ACTIVATED RECEPTORS (PPARS)

    EPA Science Inventory

    The purpose of this work was to evaluate the binding of PFAAs to PPAR receptors and determine the potential for activation or antagonism of the pathway during embryonic development. Activation of mouse and human PPAR isoforms by perfluorooctanoic acid (PFOA) and perfluorooctanes...

  9. Overexpression of Poplar Pyrabactin Resistance-Like Abscisic Acid Receptors Promotes Abscisic Acid Sensitivity and Drought Resistance in Transgenic Arabidopsis.

    PubMed

    Yu, Jingling; Yang, Lei; Liu, Xiaobing; Tang, Renjie; Wang, Yuan; Ge, Haiman; Wu, Mengting; Zhang, Jiang; Zhao, Fugeng; Luan, Sheng; Lan, Wenzhi

    2016-01-01

    Drought stress is an important environmental factor limiting productivity of plants, especially fast growing species with high water consumption like poplar. Abscisic acid (ABA) is a phytohormone that positively regulates seed dormancy and drought resistance. The PYR1 (Pyrabactin Resistance 1)/ PYRL (PYR-Like)/ RCAR (Regulatory Component of ABA Receptor) (PYR/PYL/RCAR) ABA receptor family has been identified and widely characterized in Arabidopsis thaliana. However, their functions in poplars remain unknown. Here, we report that 2 of 14 PYR/PYL/RCAR orthologues in poplar (Populus trichocarpa) (PtPYRLs) function as a positive regulator of the ABA signal transduction pathway. The Arabidopsis transient expression and yeast two-hybrid assays showed the interaction among PtPYRL1 and PtPYRL5, a clade A protein phosphatase 2C, and a SnRK2, suggesting that a core signalling complex for ABA signaling pathway exists in poplars. Phenotypic analysis of PtPYRL1 and PtPYRL5 transgenic Arabidopsis showed that these two genes positively regulated the ABA responses during the seed germination. More importantly, the overexpression of PtPYRL1 and PtPYRL5 substantially improved ABA sensitivity and drought stress tolerance in transgenic plants. In summary, we comprehensively uncovered the properties of PtPYRL1 and PtPYRL5, which might be good target genes to genetically engineer drought-Resistant plants.

  10. Hyaluronic acid and Arg-Gly-Asp peptide modified Graphene oxide with dual receptor-targeting function for cancer therapy.

    PubMed

    Guo, Yufeng; Xu, Haixing; Li, Yiping; Wu, Fengzheng; Li, Yixuan; Bao, Yun; Yan, Xiumei; Huang, Zhijun; Xu, Peihu

    2017-07-01

    Graphene oxide (GO) modified with hyaluronic acid (HA) and Arg-gly-asp peptide (RGD) was designed as a dual-receptor targeting drug delivery system to enhance the specificity and efficiency of anticancer drug delivery. Firstly, GO-HA-RGD conjugate was characterized to reveal its structure and morphology. Whereafter, doxorubicin (Dox) as a model drug was loaded on GO-HA-RGD carrier, which displayed a high loading rate (72.9%, GO:Dox (w/w) = 1:1), pH-response and sustained drug release behavior. Cytotoxicity experiments showed that GO-HA-RGD possessed excellent biocompatibility towards SKOV-3 and HOSEpiC cells. Additionally, the GO-HA-RGD/Dox had a stronger cytotoxicity for SKOV-3 cells than either GO-HA/Dox (single receptor) or GO/Dox (no receptor). Moreover, celluar uptake studies illustrated that GO-HA-RGD conjugate could be effectively taken up by SKOV-3 cells via a synergic effect of CD44-HA and integrin-RGD mediated endocytosis. Hence, GO-HA-RGD nanocarrier is able to be a promising platform for targeted cancer therapeutic.

  11. Affective and cognitive effects of global deletion of alpha3-containing gamma-aminobutyric acid-A receptors.

    PubMed

    Fiorelli, Roberto; Rudolph, Uwe; Straub, Carolin J; Feldon, Joram; Yee, Benjamin K

    2008-09-01

    Gamma-aminobutyric acid (GABA)A receptors characterized by the presence of the alpha3 subunit are the major GABAA receptor subtype expressed in brain stem monoaminergic nuclei. These alpha3-GABAA receptors are therefore in a unique position to regulate monoaminergic functions. To characterize the functional properties of alpha3-GABAA receptors, we present a preliminary assessment of the expression of affective and cognitive behaviour in male mice with a targeted deletion of the Gabra3 gene encoding the alpha3 subunit [alpha3 knockout (KO) mice] on a C57BL/6Jx129X1/SvJ F1 hybrid genetic background. The alpha3 KO mice did not exhibit any gross change of anxiety-like behaviour or spontaneous locomotor behaviour. In the Porsolt forced swim test for potential antidepressant activity, alpha3 KO mice exhibited reduced floating and enhanced swimming behaviour relative to wild-type controls. Performance on a two-choice sucrose preference test, however, revealed no evidence for an increase in sucrose preference in the alpha3 KO mice that would have substantiated a potential phenotype for depression-related behaviour. In contrast, a suggestion of an enhanced negative contrast effect was revealed in a one-bottle sucrose consumption test across different sucrose concentrations. These affective phenotypes were accompanied by alterations in the balance between conditioned responding to the discrete conditioned stimulus and to the context, and a suggestion of faster extinction, in the Pavlovian conditioned freezing paradigm. Spatial learning in the water maze reference memory test, however, was largely unchanged in the alpha3 KO mice, except for a trend of preservation during reversal learning. The novel phenotypes following global deletion of the GABAA receptor alpha3 subunit identified here provided relevant insights, in addition to our earlier study, into the potential behavioural relevance of this specific receptor subtypes in the modulation of both affective and cognitive

  12. Activation of peroxisome proliferator-activated receptor-{alpha} enhances fatty acid oxidation in human adipocytes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, Joo-Young; Hashizaki, Hikari; Goto, Tsuyoshi

    2011-04-22

    Highlights: {yields} PPAR{alpha} activation increased mRNA expression levels of adipocyte differentiation marker genes and GPDH activity in human adipocytes. {yields} PPAR{alpha} activation also increased insulin-dependent glucose uptake in human adipocytes. {yields} PPAR{alpha} activation did not affect lipid accumulation in human adipocytes. {yields} PPAR{alpha} activation increased fatty acid oxidation through induction of fatty acid oxidation-related genes in human adipocytes. -- Abstract: Peroxisome proliferator-activated receptor-{alpha} (PPAR{alpha}) is a key regulator for maintaining whole-body energy balance. However, the physiological functions of PPAR{alpha} in adipocytes have been unclarified. We examined the functions of PPAR{alpha} using human multipotent adipose tissue-derived stem cells as a humanmore » adipocyte model. Activation of PPAR{alpha} by GW7647, a potent PPAR{alpha} agonist, increased the mRNA expression levels of adipocyte differentiation marker genes such as PPAR{gamma}, adipocyte-specific fatty acid-binding protein, and lipoprotein lipase and increased both GPDH activity and insulin-dependent glucose uptake level. The findings indicate that PPAR{alpha} activation stimulates adipocyte differentiation. However, lipid accumulation was not changed, which is usually observed when PPAR{gamma} is activated. On the other hand, PPAR{alpha} activation by GW7647 treatment induced the mRNA expression of fatty acid oxidation-related genes such as CPT-1B and AOX in a PPAR{alpha}-dependent manner. Moreover, PPAR{alpha} activation increased the production of CO{sub 2} and acid soluble metabolites, which are products of fatty acid oxidation, and increased oxygen consumption rate in human adipocytes. The data indicate that activation of PPAR{alpha} stimulates both adipocyte differentiation and fatty acid oxidation in human adipocytes, suggesting that PPAR{alpha} agonists could improve insulin resistance without lipid accumulation in adipocytes. The

  13. Both genetic deletion and pharmacological blockade of lysophosphatidic acid LPA1 receptor results in increased alcohol consumption.

    PubMed

    Castilla-Ortega, Estela; Pavón, Francisco Javier; Sánchez-Marín, Laura; Estivill-Torrús, Guillermo; Pedraza, Carmen; Blanco, Eduardo; Suárez, Juan; Santín, Luis; Rodríguez de Fonseca, Fernando; Serrano, Antonia

    2016-04-01

    Lysophosphatidic acid species (LPA) are lipid bioactive signaling molecules that have been recently implicated in the modulation of emotional and motivational behaviors. The present study investigates the consequences of either genetic deletion or pharmacological blockade of lysophosphatidic acid receptor-1 (LPA1) in alcohol consumption. The experiments were performed in alcohol-drinking animals by using LPA1-null mice and administering the LPA1 receptor antagonist Ki16425 in both mice and rats. In the two-bottle free choice paradigm, the LPA1-null mice preferred the alcohol more than their wild-type counterparts. Whereas the male LPA1-null mice displayed this higher preference at all doses tested, the female LPA1-null mice only consumed more alcohol at 6% concentration. The male LPA1-null mice were then further characterized, showing a notably increased ethanol drinking after a deprivation period and a reduced sleep time after acute ethanol administration. In addition, LPA1-null mice were more anxious than the wild-type mice in the elevated plus maze test. For the pharmacological experiments, the acute administration of the antagonist Ki16425 consistently increased ethanol consumption in both wild-type mice and rats; while it did not modulate alcohol drinking in the LPA1-null mice and lacked intrinsic rewarding properties and locomotor effects in a conditioned place preference paradigm. In addition, LPA1-null mice exhibited a marked reduction on the expression of glutamate-transmission-related genes in the prefrontal cortex similar to those described in alcohol-exposed rodents. Results suggest a relevant role for the LPA/LPA1 signaling system in alcoholism. In addition, the LPA1-null mice emerge as a new model for genetic vulnerability to excessive alcohol drinking. The pharmacological manipulation of LPA1 receptor arises as a new target for the study and treatment of alcoholism. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Nutrigenomics and nutrigenetics of ω3 polyunsaturated fatty acids.

    PubMed

    Vanden Heuvel, John P

    2012-01-01

    Diets rich in ω3 polyunsaturated fatty acids (ω3-PUFAs) such as alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid are associated with decreased incidence and severity of several chronic diseases including cardiovascular disease (CVD) and cancer. At least some of the beneficial effects of these dietary fatty acids are via metabolites such as prostaglandins, leukotrienes, thromboxanes, and resolvins. The effects of ω3-PUFAs are in contrast to those of fatty acids with virtually identical structures, such as the ω6-PUFAs linoleic acid and arachidonic acid, and their corresponding metabolites. The purpose of this chapter is to discuss both the nutrigenomics (nutrient-gene interactions) and nutrigenetics (genetic variation in nutrition) of dietary fatty acids with a focus on the ω3-PUFAs (Gebauer et al., 2007(1)). Important in the biological response for these fatty acids or their metabolites are cognate receptors that are able to regulate gene expression and coordinately affect metabolic or signaling pathways associated with CVD and cancer. Four nuclear receptor (NR) subfamilies will be emphasized as receptors that respond to dietary and endogenous ligands: (1) peroxisome proliferator-activated receptors, (2) retinoid X receptors, (3) liver X receptors, and (4) farnesoid X receptor. In addition to the different responses elicited by varying structures of fatty acids, responses may vary because of genetic variation in enzymes that metabolize ω3- and ω6 fatty acids or that respond to them. In particular, polymorphisms in the fatty acid desaturases and the aforementioned NRs contribute to the complexity of nutritional effects seen with ω3-PUFAs. Following a brief introduction to the health benefits of ω3-PUFAs, the regulation of gene expression by these dietary fatty acids via NRs will be characterized. Subsequently, the effects of single-nucleotide polymorphisms (SNPs) in key enzymes involved in the metabolism and response to ω3-PUFAs will

  15. Retinoic Acid-Related Orphan Receptors (RORs): Regulatory Functions in Immunity, Development, Circadian Rhythm, and Metabolism

    PubMed Central

    Cook, Donald N.; Kang, Hong Soon; Jetten, Anton M.

    2015-01-01

    In this overview, we provide an update on recent progress made in understanding the mechanisms of action, physiological functions, and roles in disease of retinoic acid related orphan receptors (RORs). We are particularly focusing on their roles in the regulation of adaptive and innate immunity, brain function, retinal development, cancer, glucose and lipid metabolism, circadian rhythm, metabolic and inflammatory diseases and neuropsychiatric disorders. We also summarize the current status of ROR agonists and inverse agonists, including their regulation of ROR activity and their therapeutic potential for management of various diseases in which RORs have been implicated. PMID:26878025

  16. The novel, peripherally restricted GABAB receptor agonist lesogaberan (AZD3355) inhibits acid reflux and reduces esophageal acid exposure as measured with 24-h pHmetry in dogs.

    PubMed

    Brändén, Lena; Fredriksson, Anita; Harring, Emelie; Jensen, Jörgen; Lehmann, Anders

    2010-05-25

    While patients with symptoms of gastroesophageal reflux disease generally respond well to proton pump inhibitors, 20-30% continue to experience troublesome symptoms. In such cases, agents that target transient lower esophageal sphincter (LES) relaxation may be useful as add-on therapy to proton pump inhibitors. The GABAB receptor agonist baclofen inhibits transient LES relaxation but it is not an ideal agent due to central nervous system activity. Lesogaberan (AZD3355) is a peripherally restricted GABAB receptor agonist with limited central nervous system activity that inhibits transient LES relaxation in dogs. In the present study, the comparative effects of lesogaberan (7 micromol/kg) and baclofen (2.8 micromol/kg) on reflux were studied in dogs using 24-h pHmetry. Drugs (or vehicle control) were administered orally prior to the first meal of the day, and the number of reflux episodes (pH<4 for > or = 5 s) and acid exposure time were computed for the 24-h monitoring period. The mean (S.E.M.) number of reflux episodes/24 h was 4.6 (0.4) and 6.4 (0.6) for lesogaberan and baclofen, respectively, versus 10.7 (0.5) for control (P<0.0001 for both). Acid exposure time was 51.2 (4.5) min for control versus 23.6 (3.8) min for lesogaberan (P<0.0001) and 35.4 (6.5) min with baclofen (P=0.05). It is concluded that lesogaberan significantly reduces acid reflux in dogs, with comparable efficacy to baclofen. Copyright 2010 Elsevier B.V. All rights reserved.

  17. Changes in /sup 3/H-substance P receptor binding in the rat brain after kainic acid lesion of the corpus striatum

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mantyh, P.W.; Hunt, S.P.

    1986-06-01

    Previous studies have indicated that the substantia nigra contains the highest concentration of substance P-like immunoreactivity (SPLI) in the brain. Paradoxically, it also appears to contain one of the lowest concentrations of substance P receptors in the brain. One possibility is that the massive amount of SPLI blocks the binding of the radioligand to the substance P receptor and/or down-regulates the number of substance P receptors present in this structure. Since greater than 95% of the SPLI within the substantia nigra originates from the corpus striatum, we have lesioned this area and measured the changes in substance P receptor concentrationmore » in the substantia nigra and other corpus striatal projection areas. A semiquantitative autoradiographic technique for measuring the binding of /sup 3/H-substance P to substance P receptors was used in conjunction with tritium-sensitive film. 3H-substance P binding was measured in both the corpus striatum and its projection areas after kainic acid lesion of the corpus striatum. At either 4 or 21 d after the lesion there was approximately a 90% loss of substance P receptors in the rostral striatum, a 74% loss in the globus pallidus, a 57% increase in receptor number in lamina I and II of the ipsilateral somatosensory cortex, and no apparent change in the number of receptors in the substantia nigra pars reticulata, superior colliculus, and central gray. These findings suggest that the low concentration of substance P receptors found within the substantia nigra is not due the massive SPLI innervation, since removal of greater than 95% of the SPLI had no measurable effect on the concentration of substance P receptors.« less

  18. MiR-9-5p and miR-106a-5p dysregulated in CD4+ T-cells of multiple sclerosis patients and targeted essential factors of T helper17/regulatory T-cells differentiation

    PubMed Central

    Majd, Maryam; Hosseini, Aref; Ghaedi, Kamran; Kiani-Esfahani, Abbas; Tanhaei, Somayeh; Shiralian-Esfahani, Hanieh; Rahnamaee, Seyed Yahya; Mowla, Seyed Javad; Nasr-Esfahani, Mohammad Hossein

    2018-01-01

    Objective(s): Multiple sclerosis (MS) is considered as a chronic type of an inflammatory disease characterized by loss of myelin of CNS. Recent evidence indicates that Interleukin 17 (IL-17)-producing T helper cells (Th17 cells) population are increased and regulatory T cells (Treg cells) are decreased in MS. Despite extensive research in understanding the mechanism of Th17 and Treg differentiation, the role of microRNAs in MS is not completely understood. Thereby, as a step closer, we analyzed the expression profile of miR-9-5p and miR-106a-5p, and protein level of retinoic acid receptor (RAR)-related orphan receptor C (RORC; Th17 master transcription factor) as direct target of miR-106a-5p and forkhead box P3 (FOXP3; Treg master transcription factor) as indirect target of miR-9-5p in CD4+ T cells in two groups of relapsing and remitting in our relapsing-remitting MS (RR-MS) patients. Materials and Methods: Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was utilized to assess the expression of miRNAs and mRNAs, in 40 RR-MS patients and 11 healthy individuals. Thus, FOXP3 and RAR-related orphan receptor γt (RORγt) was assessed in CD4+T-cells by flow cytometry. We also investigated the role of these miRNAs in Th17/Treg differentiation pathway through bioinformatics tools. Results: An up-regulation of miR-9-5p and down-regulation of miR-106a-5p in relapsing phase of MS patients were observed compared to healthy controls. RORC and FOXP3 were up-regulated in relapsing and remitting phases of MS, respectively. Conclusion: Expression pattern of miR-9-5p and miR-106a-5p and their targets suggest a possible inducing role of miR-9-5p and suppressing role of miR-106a-5p in differentiation pathway of Th17 cells during MS pathogenesis. PMID:29511494

  19. Abscisic Acid Acts as a Blocker of the Bitter Taste G Protein-Coupled Receptor T2R4.

    PubMed

    Pydi, Sai P; Jaggupilli, Appalaraju; Nelson, Ken M; Abrams, Suzanne R; Bhullar, Rajinder P; Loewen, Michele C; Chelikani, Prashen

    2015-04-28

    Bitter taste receptors (T2Rs) belong to the G protein-coupled receptor superfamily. In humans, 25 T2Rs mediate bitter taste sensation. In addition to the oral cavity, T2Rs are expressed in many extraoral tissues, including the central nervous system, respiratory system, and reproductive system. To understand the mechanistic roles of the T2Rs in oral and extraoral tissues, novel blockers or antagonists are urgently needed. Recently, we elucidated the binding pocket of T2R4 for its agonist quinine, and an antagonist and inhibitory neurotransmitter, γ-aminobutyric acid. This structure-function information about T2R4 led us to screen the plant hormone abscisic acid (ABA), its precursor (xanthoxin), and catabolite phaseic acid for their ability to bind and activate or inhibit T2R4. Molecular docking studies followed by functional assays involving calcium imaging confirmed that ABA is an antagonist with an IC50 value of 34.4 ± 1.1 μM. However, ABA precursor xanthoxin acts as an agonist on T2R4. Interestingly, molecular model-guided site-directed mutagenesis suggests that the T2R4 residues involved in quinine binding are also predominantly involved in binding to the novel antagonist, ABA. The antagonist ability of ABA was tested using another T2R4 agonist, yohimbine. Our results suggest that ABA does not inhibit yohimbine-induced T2R4 activity. The discovery of natural bitter blockers has immense nutraceutical and physiological significance and will help in dissecting the T2R molecular pathways in various tissues.

  20. Bile alcohols function as the ligands of membrane-type bile acid-activated G protein-coupled receptor

    PubMed Central

    Iguchi, Yusuke; Yamaguchi, Masafumi; Sato, Hiroyuki; Kihira, Kenji; Nishimaki-Mogami, Tomoko; Une, Mizuho

    2010-01-01

    TGR5 is a G protein-coupled receptor that is activated by bile acids, resulting in an increase in cAMP levels and the subsequent modulation of energy expenditure in brown adipose tissue and muscle. Therefore, the development of a TGR5-specific agonist could lead to the prevention and treatment of various metabolic disorders related to obesity. In the present study, we evaluated the ability of bile alcohols, which are structurally and physiologically similar to bile acids and are produced as the end products of cholesterol catabolism in evolutionarily primitive vertebrates, to act as TGR5 agonists. In a cell-based reporter assay and a cAMP production assay performed in vitro, most bile alcohols with a side chain containing hydroxyl group(s) were highly efficacious agonists for TGR5 comparable to its most potent ligand in the naturally occurring bile acid, lithocholic acid. However, the abilities of the bile alcohols to activate TGR5 varied with the position and number of the hydroxyl substituent in the side chain. Additionally, the conformation of the steroidal nucleus of bile alcohols is also important for its activity as a TGR5 agonist. Thus, we have provided new insights into the structure-activity relationships of bile alcohols as TGR5 agonists. PMID:20023205

  1. A high fat diet containing saturated but not unsaturated fatty acids enhances T cell receptor clustering on the nanoscale.

    PubMed

    Shaikh, Saame Raza; Boyle, Sarah; Edidin, Michael

    2015-09-01

    Cell culture studies show that the nanoscale lateral organization of surface receptors, their clustering or dispersion, can be altered by changing the lipid composition of the membrane bilayer. However, little is known about similar changes in vivo, which can be effected by changing dietary lipids. We describe the use of a newly developed method, k-space image correlation spectroscopy, kICS, for analysis of quantum dot fluorescence to show that a high fat diet can alter the nanometer-scale clustering of the murine T cell receptor, TCR, on the surface of naive CD4(+) T cells. We found that diets enriched primarily in saturated fatty acids increased TCR nanoscale clustering to a level usually seen only on activated cells. Diets enriched in monounsaturated or n-3 polyunsaturated fatty acids had no effect on TCR clustering. Also none of the high fat diets affected TCR clustering on the micrometer scale. Furthermore, the effect of the diets was similar in young and middle aged mice. Our data establish proof-of-principle that TCR nanoscale clustering is sensitive to the composition of dietary fat. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Arrestin binds to different phosphorylated regions of the thyrotropin-releasing hormone receptor with distinct functional consequences.

    PubMed

    Jones, Brian W; Hinkle, Patricia M

    2008-07-01

    Arrestin binding to agonist-occupied phosphorylated G protein-coupled receptors typically increases the affinity of agonist binding, increases resistance of receptor-bound agonist to removal with high acid/salt buffer, and leads to receptor desensitization and internalization. We tested whether thyrotropin-releasing hormone (TRH) receptors lacking phosphosites in the C-terminal tail could form stable and functional complexes with arrestin. Fibroblasts from mice lacking arrestins 2 and 3 were used to distinguish between arrestin-dependent and -independent effects. Arrestin did not promote internalization or desensitization of a receptor that had key Ser/Thr phosphosites mutated to Ala (4Ala receptor). Nevertheless, arrestin greatly increased acid/salt resistance and the affinity of 4Ala receptor for TRH. Truncation of 4Ala receptor just distal to the key phosphosites (4AlaStop receptor) abolished arrestin-dependent acid/salt resistance but not the effect of arrestin on agonist affinity. Arrestin formed stable complexes with activated wild-type and 4Ala receptors but not with 4AlaStop receptor, as measured by translocation of arrestin-green fluorescent protein to the plasma membrane or chemical cross-linking. An arrestin mutant that does not interact with clathrin and AP2 did not internalize receptor but still promoted high affinity TRH binding, acid/salt resistance, and desensitization. A sterically restricted arrestin mutant did not cause receptor internalization or desensitization but did promote acid/salt resistance and high agonist affinity. The results demonstrate that arrestin binds to proximal or distal phosphosites in the receptor tail. Arrestin binding at either site causes increased agonist affinity and acid/salt resistance, but only the proximal phosphosites evoke the necessary conformational changes in arrestin for receptor desensitization and internalization.

  3. A NAD(P) reductase like protein is the salicylic acid receptor in the appendix of the Sauromatum guttatum inflorescence

    PubMed Central

    Skubatz, Hanna; Orellana, Mónica V; Howald, William N

    2013-01-01

    The mode of action of the thermogenic inducers (salicylic acid, aspirin, and 2,6-dihydroxybenzoic acid) in the appendix of the Sauromatum guttatum inflorescence is poorly understood. Using ESI-MS and light scattering analysis, we have demonstrated that NAD(P) reductase like protein (RL) is the salicylic acid receptor in the Sauromatum appendix. RL was self-assembled in water into a large unit with a hydrodynamic diameter of 800 nm. In the presence of 1 pM salicylic acid, RL exhibited discontinuous and reversible volume phase transitions. The volume phase changed from 800 to 300 nm diameter and vice versa. RL stayed at each volume phase for ~4–5 min with a fast relaxation time between the 2 phases. ESI-MS analysis of RL extracted from appendices treated with salicylic acid, aspirin, and 2,6-DHBA at a micromolar range demonstrated that these compounds are capable of inducing graded conformational changes that are concentration-dependent. A strong correlation between RL conformations and heat-production induced by salicylic acid was also observed. These preliminary findings reveal structural and conformational roles for RL by which plants regulate their temperature and synchronize their time keeping mechanisms. PMID:28516022

  4. Signaling cross-talk between peroxisome proliferator-activated receptor/retinoid X receptor and estrogen receptor through estrogen response elements.

    PubMed

    Keller, H; Givel, F; Perroud, M; Wahli, W

    1995-07-01

    Peroxisome proliferator-activated receptors (PPARs) and retinoid X receptors (RXRs) are nuclear hormone receptors that are activated by fatty acids and 9-cis-retinoic acid, respectively. PPARs and RXRs form heterodimers that activate transcription by binding to PPAR response elements (PPREs) in the promoter of target genes. The PPREs described thus far consist of a direct tandem repeat of the AGGTCA core element with one intervening nucleotide. We show here that the vitellogenin A2 estrogen response element (ERE) can also function as a PPRE and is bound by a PPAR/RXR heterodimer. Although this heterodimer can bind to several other ERE-related palindromic response elements containing AGGTCA half-sites, only the ERE is able to confer transactivation of test reporter plasmids, when the ERE is placed either close to or at a distance from the transcription initiation site. Examination of natural ERE-containing promoters, including the pS2, very-low-density apolipoprotein II and vitellogenin A2 genes, revealed considerable differences in the binding of PPAR/RXR heterodimers to these EREs. In their natural promoter context, these EREs did not allow transcriptional activation by PPARs/RXRs. Analysis of this lack of stimulation of the vitellogenin A2 promoter demonstrated that PPARs/RXRs bind to the ERE but cannot transactivate due to a nonpermissive promoter structure. As a consequence, PPARs/RXRs inhibit transactivation by the estrogen receptor through competition for ERE binding. This is the first example of signaling cross-talk between PPAR/RXR and estrogen receptor.

  5. Regulation of Ion Transport in the Intestine by Free Fatty Acid Receptor 2 and 3: Possible Involvement of the Diffuse Chemosensory System

    PubMed Central

    Kuwahara, Atsukazu; Kuwahara, Yuko; Inui, Toshio; Marunaka, Yoshinori

    2018-01-01

    The diffuse chemosensory system (DCS) is well developed in the apparatuses of endodermal origin like gastrointestinal (GI) tract. The primary function of the GI tract is the extraction of nutrients from the diet. Therefore, the GI tract must possess an efficient surveillance system that continuously monitors the luminal contents for beneficial or harmful compounds. Recent studies have shown that specialized cells in the intestinal lining can sense changes in the luminal content. The chemosensory cells in the GI tract belong to the DCS which consists of enteroendocrine and related cells. These cells initiate various important local and remote reflexes. Although neural and hormonal involvements in ion transport in the GI tract are well documented, involvement of the DCS in the regulation of intestinal ion transport is much less understood. Since activation of luminal chemosensory receptors is a primary signal that elicits changes in intestinal ion transport and motility and failure of the system causes dysfunctions in host homeostasis, as well as functional GI disorders, study of the regulation of GI function by the DCS has become increasingly important. This review discusses the role of the DCS in epithelial ion transport, with particular emphasis on the involvement of free fatty acid receptor 2 (FFA2) and free fatty acid receptor 3 (FFA3). PMID:29510573

  6. Induction of HoxB Transcription by Retinoic Acid Requires Actin Polymerization

    PubMed Central

    Ferrai, Carmelo; Naum-Onganía, Gabriela; Longobardi, Elena; Palazzolo, Martina; Disanza, Andrea; Diaz, Victor M.; Crippa, Massimo P.; Scita, Giorgio

    2009-01-01

    We have analyzed the role of actin polymerization in retinoic acid (RA)-induced HoxB transcription, which is mediated by the HoxB regulator Prep1. RA induction of the HoxB genes can be prevented by the inhibition of actin polymerization. Importantly, inhibition of actin polymerization specifically affects the transcription of inducible Hox genes, but not that of their transcriptional regulators, the RARs, nor of constitutively expressed, nor of actively transcribed Hox genes. RA treatment induces the recruitment to the HoxB2 gene enhancer of a complex composed of “elongating” RNAPII, Prep1, β-actin, and N-WASP as well as the accessory splicing components p54Nrb and PSF. We show that inhibition of actin polymerization prevents such recruitment. We conclude that inducible Hox genes are selectively sensitive to the inhibition of actin polymerization and that actin polymerization is required for the assembly of a transcription complex on the regulatory region of the Hox genes. PMID:19477923

  7. Induction of HoxB transcription by retinoic acid requires actin polymerization.

    PubMed

    Ferrai, Carmelo; Naum-Onganía, Gabriela; Longobardi, Elena; Palazzolo, Martina; Disanza, Andrea; Diaz, Victor M; Crippa, Massimo P; Scita, Giorgio; Blasi, Francesco

    2009-08-01

    We have analyzed the role of actin polymerization in retinoic acid (RA)-induced HoxB transcription, which is mediated by the HoxB regulator Prep1. RA induction of the HoxB genes can be prevented by the inhibition of actin polymerization. Importantly, inhibition of actin polymerization specifically affects the transcription of inducible Hox genes, but not that of their transcriptional regulators, the RARs, nor of constitutively expressed, nor of actively transcribed Hox genes. RA treatment induces the recruitment to the HoxB2 gene enhancer of a complex composed of "elongating" RNAPII, Prep1, beta-actin, and N-WASP as well as the accessory splicing components p54Nrb and PSF. We show that inhibition of actin polymerization prevents such recruitment. We conclude that inducible Hox genes are selectively sensitive to the inhibition of actin polymerization and that actin polymerization is required for the assembly of a transcription complex on the regulatory region of the Hox genes.

  8. The role of S-nitrosylation of kainate-type of ionotropic glutamate receptor 2 in epilepsy induced by kainic acid.

    PubMed

    Wang, Linxiao; Liu, Yanyan; Lu, Rulan; Dong, Guoying; Chen, Xia; Yun, Wenwei; Zhou, Xianju

    2018-02-01

    Epilepsy is a chronic brain disease affecting millions of individuals. Kainate receptors, especially kainate-type of ionotropic glutamate receptor 2 (GluK2), play an important role in epileptogenesis. Recent data showed that GluK2 could undergo post-translational modifications in terms of S-nitrosylation (SNO), and affect the signaling pathway of cell death in cerebral ischemia-reperfusion. However, it is unclear whether S-nitrosylation of GluK2 (SNO-GluK2) contributes to cell death induced by epilepsy. Here, we report that kainic acid-induced SNO-GluK2 is mediated by GluK2 itself, regulated by neuronal nitric oxide synthase (nNOS) and the level of cytoplasmic calcium in vivo and in vitro hippocampus neurons. The whole-cell patch clamp recordings showed the influence of SNO-GluK2 on ion channel characterization of GluK2-Kainate receptors. Moreover, immunohistochemistry staining results showed that inhibition of SNO-GluK2 by blocking nNOS or GluK2 or by reducing the level of cytoplasmic calcium-protected hippocampal neurons from kainic acid-induced injury. Finally, immunoprecipitation and western blotting data revealed the involvement of assembly of a GluK2-PSD95-nNOS signaling complex in epilepsy. Taken together, our results showed that the SNO-GluK2 plays an important role in neuronal injury of epileptic rats by forming GluK2-PSD95-nNOS signaling module in a cytoplasmic calcium-dependent way, suggesting a potential therapeutic target site for epilepsy. © 2017 International Society for Neurochemistry.

  9. Group III mGlu receptor agonists potentiate the anticonvulsant effect of AMPA and NMDA receptor block.

    PubMed

    De Sarro, Giovambattista; Chimirri, Alba; Meldrum, Brian S

    2002-09-06

    We report the anticonvulsant action in DBA/2 mice of two mGlu Group III receptor agonists: (R,S)-4-phosphonophenylglycine, (R,S)-PPG, a compound with moderate mGlu8 selectivity, and of (1S,3R,4S)-1-aminocyclopentane-1,2,4-tricarboxylic acid, ACPT-1, a selective agonist for mGlu4alpha receptors. Both compounds, given intracerebroventricularly at doses which did not show marked anticonvulsant activity, produced a consistent shift to the left of the dose-response curves (i.e. enhanced the anticonvulsant properties) of 1-(4'-aminophenyl)-3,5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-one hydrochloride, CFM-2, a noncompetitive AMPA receptor antagonist, and 3-((+/-)-2-carboxypiperazin-4-yl)-1-phosphonic acid, CPPene, a competitive NMDA receptor antagonist, in DBA/2 mice. In addition, (R,S)-PPG and ACPT-1 administered intracerebroventricularly prolonged the time course of the anticonvulsant properties of CFM-2 (33 micromol/kg, i.p.) and CPPene (3.3 micromol/kg, i.p.) administered intraperitoneally. We conclude that modest reduction of synaptic glutamate release by activation of Group III metabotropic receptors potentiates the anticonvulsant effect of AMPA and NMDA receptor blockade. Copyright 2002 Elsevier Science B.V.

  10. Structural basis and functions of abscisic acid receptors PYLs

    PubMed Central

    Zhang, Xing L.; Jiang, Lun; Xin, Qi; Liu, Yang; Tan, Jian X.; Chen, Zhong Z.

    2015-01-01

    Abscisic acid (ABA) plays a key role in many developmental processes and responses to adaptive stresses in plants. Recently, a new family of nucleocytoplasmic PYR/PYL/RCAR (PYLs) has been identified as bona fide ABA receptors. PYLs together with protein phosphatases type-2C (PP2Cs), Snf1 (Sucrose-non-fermentation 1)-related kinases subfamily 2 (SnRK2s) and downstream substrates constitute the core ABA signaling network. Generally, PP2Cs inactivate SnRK2s kinases by physical interaction and direct dephosphorylation. Upon ABA binding, PYLs change their conformations and then contact and inhibit PP2Cs, thus activating SnRK2s. Here, we reviewed the recent progress in research regarding the structures of the core signaling pathways of ABA, including the (+)-ABA, (−)-ABA and ABA analogs pyrabactin as well as 6AS perception by PYLs, SnRK2s mimicking PYLs in binding PP2Cs. PYLs inhibited PP2Cs in both the presence and absence of ABA and activated SnRK2s. The present review elucidates multiple ABA signal perception and transduction by PYLs, which might shed light on how to design small chemical compounds for improving plant performance in the future. PMID:25745428

  11. 4-Alkylated homoibotenic acid (HIBO) analogues: versatile pharmacological agents with diverse selectivity profiles towards metabotropic and ionotropic glutamate receptor subtypes.

    PubMed

    Madsen, Ulf; Pickering, Darryl S; Nielsen, Birgitte; Bräuner-Osborne, Hans

    2005-01-01

    4-Alkylated analogues of homoibotenic acid (HIBO) have previously shown high potency and selectivity at ionotropic and metabotropic glutamic acid receptor (iGluR and mGluR) subtypes. Compounds with different selectivity profiles are valuable pharmacological tools for neuropharmacological studies, and the series of 4-alkyl-HIBO analogues have been extended in this paper in the search for versatile agents. Pharmacological characterization of five new analogues, branched and unbranched 4-alkyl-HIBO analogues, have been carried out. The present compounds are all weak antagonists at Group I mGluRs (mGluR1 and 5) presenting only small differences in potencies (Ki values ranging from 89 to 670 microM). Affinities were studied at native and cloned iGluRs, and the compounds described show preference for the AMPA receptor subtypes GluR1 and 2 over GluR3 and 4. However, compared to previous 4-alkyl-HIBO analogues, these compounds show a remarkably high affinity for the Kain preferring subtype GluR5. The observed GluR5 affinities were either similar or higher compared to their GluR1 and 2 affinity. Isopropyl-HIBO showed the highest affinity for GluR5 (Ki=0.16 microM), and represents a unique compound with high affinity towards the three subtypes GluR1, 2 and 5. In general, these compounds represent new selectivity profiles compared to previously reported Glu receptor analogues.

  12. Linking γ-aminobutyric acid A receptor to epidermal growth factor receptor pathways activation in human prostate cancer.

    PubMed

    Wu, Weijuan; Yang, Qing; Fung, Kar-Ming; Humphreys, Mitchell R; Brame, Lacy S; Cao, Amy; Fang, Yu-Ting; Shih, Pin-Tsen; Kropp, Bradley P; Lin, Hsueh-Kung

    2014-03-05

    Neuroendocrine (NE) differentiation has been attributed to the progression of castration-resistant prostate cancer (CRPC). Growth factor pathways including the epidermal growth factor receptor (EGFR) signaling have been implicated in the development of NE features and progression to a castration-resistant phenotype. However, upstream molecules that regulate the growth factor pathway remain largely unknown. Using androgen-insensitive bone metastasis PC-3 cells and androgen-sensitive lymph node metastasis LNCaP cells derived from human prostate cancer (PCa) patients, we demonstrated that γ-aminobutyric acid A receptor (GABA(A)R) ligand (GABA) and agonist (isoguvacine) stimulate cell proliferation, enhance EGF family members expression, and activate EGFR and a downstream signaling molecule, Src, in both PC-3 and LNCaP cells. Inclusion of a GABA(A)R antagonist, picrotoxin, or an EGFR tyrosine kinase inhibitor, Gefitinib (ZD1839 or Iressa), blocked isoguvacine and GABA-stimulated cell growth, trans-phospohorylation of EGFR, and tyrosyl phosphorylation of Src in both PCa cell lines. Spatial distributions of GABAAR α₁ and phosphorylated Src (Tyr416) were studied in human prostate tissues by immunohistochemistry. In contrast to extremely low or absence of GABA(A)R α₁-positive immunoreactivity in normal prostate epithelium, elevated GABA(A)R α₁ immunoreactivity was detected in prostate carcinomatous glands. Similarly, immunoreactivity of phospho-Src (Tyr416) was specifically localized and limited to the nucleoli of all invasive prostate carcinoma cells, but negative in normal tissues. Strong GABAAR α₁ immunoreactivity was spatially adjacent to the neoplastic glands where strong phospho-Src (Tyr416)-positive immunoreactivity was demonstrated, but not in adjacent to normal glands. These results suggest that the GABA signaling is linked to the EGFR pathway and may work through autocrine or paracine mechanism to promote CRPC progression. Copyright © 2013 Elsevier

  13. Inhibitory effects of azole-type fungicides on interleukin-17 gene expression via retinoic acid receptor-related orphan receptors α and γ

    PubMed Central

    Kojima, Hiroyuki; Muromoto, Ryuta; Takahashi, Miki; Takeuchi, Shinji; Takeda, Yukimasa; Jetten, Anton M.; Matsuda, Tadashi

    2013-01-01

    The retinoic acid receptor-related orphan receptors α and γ (RORα and RORγ), are key regulators of helper T (Th)17 cell differentiation, which is involved in the innate immune system and autoimmune disorders. However, it remains unclear whether environmental chemicals, including pesticides, have agonistic and/or antagonistic activity against RORα/γ. In this study, we investigated the RORα/γ activity of several azole-type fungicides, and the effects of these fungicides on the gene expression of interleukin (IL)-17, which mediates the function of Th17 cells. In the ROR-reporter gene assays, five azole-type fungicides (imibenconazole, triflumizole, hexaconazole, tetraconazole and imazalil) suppressed RORα- and/or RORγ-mediated transcriptional activity as did benzenesulphonamide T0901317, a ROR inverse agonist and a liver X receptor (LXR) agonist. In particular, imibenconazole, triflumizole and hexaconazole showed RORγ inverse agonistic activity at concentrations of 10−6 M. However, unlike T0901317, these fungicides failed to show any LXRα/β agonistic activity. Next, five azole-type fungicides, showing ROR inverse agonist activity, were tested on IL-17 mRNA expression in mouse T lymphoma EL4 cells treated with phorbol myristate acetate and ionomycin. The quantitative RT-PCR analysis revealed that these fungicides suppressed the expression of IL-17 mRNA without effecting RORα and RORγ mRNA levels. In addition, the inhibitory effect of imibenconazole as well as that of T0901317 was absorbed in RORα/γ-knocked down EL4 cells. Taken together, these results suggest that some azole-type fungicides inhibit IL-17 production via RORα/γ. This also provides the first evidence that environmental chemicals can act as modulators of IL-17 expression in immune cells. PMID:22289359

  14. Cannabidiolic acid methyl ester, a stable synthetic analogue of cannabidiolic acid, can produce 5-HT1A receptor-mediated suppression of nausea and anxiety in rats.

    PubMed

    Pertwee, Roger G; Rock, Erin M; Guenther, Kelsey; Limebeer, Cheryl L; Stevenson, Lesley A; Haj, Christeene; Smoum, Reem; Parker, Linda A; Mechoulam, Raphael

    2018-01-01

    The aim of this study was to compare the abilities of cannabidiolic acid methyl ester (HU-580) and cannabidiolic acid (CBDA) to enhance 5-HT 1A receptor activation in vitro and produce 5-HT 1A -mediated reductions in nausea and anxiety in vivo. We investigated the effects of HU-580 and CBDA on (i) activation by 8-hydroxy-2-(di-n-propylamino)tetralin of human 5-HT 1A receptors in CHO cell membranes, using [ 35 S]-GTPγS binding assays, (ii) gaping by rats in acute and anticipatory nausea models, and (iii) stress-induced anxiety-like behaviour, as indicated by exit time from the light compartment of a light-dark box of rats subjected 24 h earlier to six tone-paired foot shocks. HU-580 and CBDA increased the E max of 8-hydroxy-2-(di-n-propylamino) tetralin in vitro at 0.01-10 and 0.1-10 nM, respectively, and reduced signs of (i) acute nausea at 0.1 and 1 μg·kg -1 i.p. and at 1 μg·kg -1 i.p., respectively, and (ii) anticipatory nausea at 0.01 and 0.1 μg·kg -1 , and at 0.1 μg·kg -1 i.p. respectively. At 0.01 μg·kg -1 , HU-580, but not CBDA, increased the time foot-shocked rats spent in the light compartment of a light-dark box. The anti-nausea and anti-anxiety effects of 0.01 or 0.1 μg·kg -1 HU-580 were opposed by the 5-HT 1A antagonist, WAY100635 (0.1 mg·kg -1 i.p.). HU-580 is more potent than CBDA at enhancing 5-HT 1A receptor activation, and inhibiting signs of acute and anticipatory nausea, and anxiety. Consequently, HU-580 is a potential medicine for treating some nausea and anxiety disorders and possibly other disorders ameliorated by enhancement of 5-HT 1A receptor activation. © 2017 The British Pharmacological Society.

  15. Selective labeling of serotonin receptors by d-[3H]lysergic acid diethylamide in calf caudate.

    PubMed Central

    Whitaker, P M; Seeman, P

    1978-01-01

    Since it was known that d-lysergic acid diethylamide (LSD) affected catecholaminergic as well as serotoninergic neurons, the objective in this study was to enhance the selectivity of [3H]LSD binding to serotonin receptors in vitro by using crude homogenates of calf caudate. In the presence of a combination of 50 nM each of phentolamine (added to preclude the binding of [3H]LSD to alpha-adrenoceptors), apomorphine, and spiperone (added to preclude the binding of [3H]LSD to dopamine receptors), it was found by Scatchard analysis that the total number of [3H]LSD sites went down to 300 fmol/mg, compared to 1100 fmol/mg in the absence of the catecholamine-blocking drugs. The IC50 values (concentrations to inhibit binding by 50%) for various drugs were tested on the binding of [3H]LSD in the presence of 50 nM each of apomorphine (A), phentolamine (P) and spiperone (S). With this combination, the IC50 for serotonin was 35 nM (compared to 1000 nM without it), indicating that [3H]LSD had become considerably more selectively displaceable by serotonin under these conditions whereas the effects of norepinephrine and dopamine on [3H]LSD binding were eliminated. Various ergots had approximately equal IC50 values against [3H]serotonin and [3H]LSD but tryptamines were much more selective against [3H]serotonin; the data may indicate the existence of the two types of serotonin receptors. PMID:32537

  16. Back to the future: Rational maps for exploring acetylcholine receptor space and time.

    PubMed

    Tessier, Christian J G; Emlaw, Johnathon R; Cao, Zhuo Qian; Pérez-Areales, F Javier; Salameh, Jean-Paul J; Prinston, Jethro E; McNulty, Melissa S; daCosta, Corrie J B

    2017-11-01

    Global functions of nicotinic acetylcholine receptors, such as subunit cooperativity and compatibility, likely emerge from a network of amino acid residues distributed across the entire pentameric complex. Identification of such networks has stymied traditional approaches to acetylcholine receptor structure and function, likely due to the cryptic interdependency of their underlying amino acid residues. An emerging evolutionary biochemistry approach, which traces the evolutionary history of acetylcholine receptor subunits, allows for rational mapping of acetylcholine receptor sequence space, and offers new hope for uncovering the amino acid origins of these enigmatic properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Boronic acid-containing CXCR1/2 antagonists: optimization of metabolic stability, in vivo evaluation, and a proposed receptor binding model

    PubMed Central

    Maeda, Dean Y.; Peck, Angela M.; Schuler, Aaron D.; Quinn, Mark T.; Kirpotina, Liliya N.; Wicomb, Winston N.; Auten, Richard L.; Gundla, Rambabu; Zebala, John A.

    2015-01-01

    Blockade of undesired neutrophil migration to sites of inflammation remains an area of substantial pharmaceutical interest. To effect this blockade, a validated therapeutic target is antagonism of the chemokine receptor CXCR2. Herein we report the discovery of 6-(2-boronic acid-5-trifluoromethoxy-benzylsulfanyl)-N-(4-fluoro-phenyl)-nicotinamide 6, an antagonist with activity at both CXCR1 and CXCR2 receptors (IC50 values 31 and 21 nM, respectively). Compound 6 exhibited potent inhibition of neutrophil influx in a rat model of pulmonary inflammation, and is hypothesized to interact with a unique intracellular binding site on CXCR2. Compound 6 (SX-576) is undergoing further investigation as a potential therapy for pulmonary inflammation. PMID:25933594

  18. Inhibitory effects of azole-type fungicides on interleukin-17 gene expression via retinoic acid receptor-related orphan receptors α and γ

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kojima, Hiroyuki, E-mail: kojima@iph.pref.hokkaido.jp; Muromoto, Ryuta; Takahashi, Miki

    2012-03-15

    The retinoic acid receptor-related orphan receptors α and γ (RORα and RORγ), are key regulators of helper T (Th)17 cell differentiation, which is involved in the innate immune system and autoimmune disorders. However, it remains unclear whether environmental chemicals, including pesticides, have agonistic and/or antagonistic activity against RORα/γ. In this study, we investigated the RORα/γ activity of several azole-type fungicides, and the effects of these fungicides on the gene expression of interleukin (IL)-17, which mediates the function of Th17 cells. In the ROR-reporter gene assays, five azole-type fungicides (imibenconazole, triflumizole, hexaconazole, tetraconazole and imazalil) suppressed RORα- and/or RORγ-mediated transcriptional activitymore » as did benzenesulphonamide T0901317, a ROR inverse agonist and a liver X receptor (LXR) agonist. In particular, imibenconazole, triflumizole and hexaconazole showed RORγ inverse agonistic activity at concentrations of 10{sup −6} M. However, unlike T0901317, these fungicides failed to show any LXRα/β agonistic activity. Next, five azole-type fungicides, showing ROR inverse agonist activity, were tested on IL-17 mRNA expression in mouse T lymphoma EL4 cells treated with phorbol myristate acetate and ionomycin. The quantitative RT-PCR analysis revealed that these fungicides suppressed the expression of IL-17 mRNA without effecting RORα and RORγ mRNA levels. In addition, the inhibitory effect of imibenconazole as well as that of T0901317 was absorbed in RORα/γ-knocked down EL4 cells. Taken together, these results suggest that some azole-type fungicides inhibit IL-17 production via RORα/γ. This also provides the first evidence that environmental chemicals can act as modulators of IL-17 expression in immune cells. -- Highlights: ► Nuclear receptors, RORα and RORγ, are key regulators of Th17 cell differentiation. ► Five azole-type fungicides act as RORα/γ inverse agonists. ► These

  19. Lysophosphatidic Acid Signals through Multiple Receptors in Osteoclasts to Elevate Cytosolic Calcium Concentration, Evoke Retraction, and Promote Cell Survival*

    PubMed Central

    Lapierre, Danielle M.; Tanabe, Natsuko; Pereverzev, Alexey; Spencer, Martha; Shugg, Ryan P. P.; Dixon, S. Jeffrey; Sims, Stephen M.

    2010-01-01

    Lysophosphatidic acid (LPA) is a bioactive phospholipid whose functions are mediated by multiple G protein-coupled receptors. We have shown that osteoblasts produce LPA, raising the possibility that it mediates intercellular signaling among osteoblasts and osteoclasts. Here we investigated the expression, signaling and function of LPA receptors in osteoclasts. Focal application of LPA elicited transient increases in cytosolic calcium concentration ([Ca2+]i), with 50% of osteoclasts responding at ∼400 nm LPA. LPA-induced elevation of [Ca2+]i was blocked by pertussis toxin or the LPA1/3 receptor antagonist VPC-32183. LPA caused sustained retraction of osteoclast lamellipodia and disrupted peripheral actin belts. Retraction was insensitive to VPC-32183 or pertussis toxin, indicating involvement of a distinct signaling pathway. In this regard, inhibition of Rho-associated kinase stimulated respreading after LPA-induced retraction. Real-time reverse transcription-PCR revealed transcripts encoding LPA1 and to a lesser extent LPA2, LPA4, and LPA5 receptor subtypes. LPA induced nuclear translocation of NFATc1 and enhanced osteoclast survival, effects that were blocked by VPC-32183 or by a specific peptide inhibitor of NFAT activation. LPA slightly reduced the resorptive activity of osteoclasts in vitro. Thus, LPA binds to at least two receptor subtypes on osteoclasts: LPA1, which couples through Gi/o to elevate [Ca2+]i, activate NFATc1, and promote survival, and a second receptor that likely couples through G12/13 and Rho to evoke and maintain retraction through reorganization of the actin cytoskeleton. These findings reveal a signaling axis in bone through which LPA, produced by osteoblasts, acts on multiple receptor subtypes to induce pleiotropic effects on osteoclast activity and function. PMID:20551326

  20. Cannabinoid receptor-dependent and -independent anti-proliferative effects of omega-3 ethanolamides in androgen receptor-positive and -negative prostate cancer cell lines

    PubMed Central

    Brown, Iain; Cascio, Maria G.; Wahle, Klaus W.J.; Smoum, Reem; Mechoulam, Raphael; Ross, Ruth A.; Pertwee, Roger G.; Heys, Steven D.

    2010-01-01

    The omega-3 fatty acid ethanolamides, docosahexaenoyl ethanolamide (DHEA) and eicosapentaenoyl ethanolamide (EPEA), displayed greater anti-proliferative potency than their parent omega-3 fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), in LNCaP and PC3 prostate cancer cells. DHEA and EPEA activated cannabinoid CB1 and CB2 receptors in vitro with significant potency, suggesting that they are endocannabinoids. Both LNCaP and PC3 cells expressed CB1 and CB2 receptors, and the CB1- and CB2-selective antagonists, AM281 and AM630, administered separately or together, reduced the anti-proliferative potencies of EPEA and EPA but not of DHEA or DHA in PC3 cells and of EPA but not of EPEA, DHEA or DHA in LNCaP cells. Even so, EPEA and EPA may not have inhibited PC3 or LNCaP cell proliferation via cannabinoid receptors since the anti-proliferative potency of EPEA was well below the potency it displayed as a CB1 or CB2 receptor agonist. Indeed, these receptors may mediate a protective effect because the anti-proliferative potency of DHEA in LNCaP and PC3 cells was increased by separate or combined administration of AM281 and AM630. The anandamide-metabolizing enzyme, fatty acid amide hydrolase (FAAH), was highly expressed in LNCaP but not PC3 cells. Evidence was obtained that FAAH metabolizes EPEA and DHEA and that the anti-proliferative potencies of these ethanolamides in LNCaP cells can be enhanced by inhibiting this enzyme. Our findings suggest that the expression of cannabinoid receptors and of FAAH in some tumour cells could well influence the effectiveness of DHA and EPA or their ethanolamide derivatives as anticancer agents. PMID:20660502