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Sample records for receptor activating properties

  1. Pharmacological analysis of the activation and receptor properties of the tonic GABA(CR current in retinal bipolar cell terminals.

    Directory of Open Access Journals (Sweden)

    Stefanie M Jones

    Full Text Available GABAergic inhibition in the central nervous system (CNS can occur via rapid, transient postsynaptic currents and via a tonic increase in membrane conductance, mediated by synaptic and extrasynaptic GABA(A receptors (GABA(ARs respectively. Retinal bipolar cells (BCs exhibit a tonic current mediated by GABA(CRs in their axon terminal, in addition to synaptic GABA(AR and GABA(CR currents, which strongly regulate BC output. The tonic GABA(CR current in BC terminals (BCTs is not dependent on vesicular GABA release, but properties such as the alternative source of GABA and the identity of the GABA(CRs remain unknown. Following a recent report that tonic GABA release from cerebellar glial cells is mediated by Bestrophin 1 anion channels, we have investigated their role in non-vesicular GABA release in the retina. Using patch-clamp recordings from BCTs in goldfish retinal slices, we find that the tonic GABA(CR current is not reduced by the anion channel inhibitors NPPB or flufenamic acid but is reduced by DIDS, which decreases the tonic current without directly affecting GABA(CRs. All three drugs also exhibit non-specific effects including inhibition of GABA transporters. GABA(CR ρ subunits can form homomeric and heteromeric receptors that differ in their properties, but BC GABA(CRs are thought to be ρ1-ρ2 heteromers. To investigate whether GABA(CRs mediating tonic and synaptic currents may differ in their subunit composition, as is the case for GABA(ARs, we have examined the effects of two antagonists that show partial ρ subunit selectivity: picrotoxin and cyclothiazide. Tonic and synaptic GABA(CR currents were differentially affected by both drugs, suggesting that a population of homomeric ρ1 receptors contributes to the tonic current. These results extend our understanding of the multiple forms of GABAergic inhibition that exist in the CNS and contribute to visual signal processing in the retina.

  2. The Cannabinoid Receptor CB1 Modulates the Signaling Properties of the Lysophosphatidylinositol Receptor GPR55*

    Science.gov (United States)

    Kargl, Julia; Balenga, Nariman; Parzmair, Gerald P.; Brown, Andrew J.; Heinemann, Akos; Waldhoer, Maria

    2012-01-01

    The G protein-coupled receptor (GPCR) 55 (GPR55) and the cannabinoid receptor 1 (CB1R) are co-expressed in many tissues, predominantly in the central nervous system. Seven transmembrane spanning (7TM) receptors/GPCRs can form homo- and heteromers and initiate distinct signaling pathways. Recently, several synthetic CB1 receptor inverse agonists/antagonists, such as SR141716A, AM251, and AM281, were reported to activate GPR55. Of these, SR141716A was marketed as a promising anti-obesity drug, but was withdrawn from the market because of severe side effects. Here, we tested whether GPR55 and CB1 receptors are capable of (i) forming heteromers and (ii) whether such heteromers could exhibit novel signaling patterns. We show that GPR55 and CB1 receptors alter each others signaling properties in human embryonic kidney (HEK293) cells. We demonstrate that the co-expression of FLAG-CB1 receptors in cells stably expressing HA-GPR55 specifically inhibits GPR55-mediated transcription factor activation, such as nuclear factor of activated T-cells and serum response element, as well as extracellular signal-regulated kinases (ERK1/2) activation. GPR55 and CB1 receptors can form heteromers, but the internalization of both receptors is not affected. In addition, we observe that the presence of GPR55 enhances CB1R-mediated ERK1/2 and nuclear factor of activated T-cell activation. Our data provide the first evidence that GPR55 can form heteromers with another 7TM/GPCR and that this interaction with the CB1 receptor has functional consequences in vitro. The GPR55-CB1R heteromer may play an important physiological and/or pathophysiological role in tissues endogenously co-expressing both receptors. PMID:23161546

  3. Membrane cholesterol content influences binding properties of muscarinic M2 receptors and differentially impacts activation of second messenger pathways

    Czech Academy of Sciences Publication Activity Database

    Michal, Pavel; Rudajev, Vladimír; El-Fakahany, E. E.; Doležal, Vladimír

    2009-01-01

    Roč. 606, 1-3 (2009), s. 50-60 ISSN 0014-2999 R&D Projects: GA ČR(CZ) GA305/05/0452; GA AV ČR(CZ) IAA500110703; GA MŠk(CZ) LC554 Grant - others:National Institutes of Health(US) NS25743; EC(XE) LipiDiDiet Institutional research plan: CEZ:AV0Z50110509 Keywords : muscarinic * cholesterol * receptors Subject RIV: ED - Physiology Impact factor: 2.585, year: 2009

  4. Novel Functional Properties of Drosophila CNS Glutamate Receptors

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan; Dharkar, Poorva; Han, Tae-Hee; Serpe, Mihaela; Lee, Chi-Hon; Mayer, Mark L.

    2016-12-01

    Phylogenetic analysis reveals AMPA, kainate, and NMDA receptor families in insect genomes, suggesting conserved functional properties corresponding to their vertebrate counterparts. However, heterologous expression of the Drosophila kainate receptor DKaiR1D and the AMPA receptor DGluR1A revealed novel ligand selectivity at odds with the classification used for vertebrate glutamate receptor ion channels (iGluRs). DKaiR1D forms a rapidly activating and desensitizing receptor that is inhibited by both NMDA and the NMDA receptor antagonist AP5; crystallization of the KaiR1D ligand-binding domain reveals that these ligands stabilize open cleft conformations, explaining their action as antagonists. Surprisingly, the AMPA receptor DGluR1A shows weak activation by its namesake agonist AMPA and also by quisqualate. Crystallization of the DGluR1A ligand-binding domain reveals amino acid exchanges that interfere with binding of these ligands. The unexpected ligand-binding profiles of insect iGluRs allows classical tools to be used in novel approaches for the study of synaptic regulation.

  5. Immunomodulatory properties of mesenchymal stem cells derived from dental pulp and dental follicle are susceptible to activation by toll-like receptor agonists.

    Science.gov (United States)

    Tomic, Sergej; Djokic, Jelena; Vasilijic, Sasa; Vucevic, Dragana; Todorovic, Vera; Supic, Gordana; Colic, Miodrag

    2011-04-01

    Adult mesenchymal stem cells (MSCs) have recently become a potent tool in regenerative medicine. Due to certain shortcomings of obtaining bone marrow MSCs, alternate sources of MSCs have been sought. In this work, we studied MSCs from dental pulp (DP-MSCs) and dental follicle (DF-MSCs), isolated from the same tooth/donor, to define differences in their phenotypic properties, differentiation potential, and immunomodulatory activities. Both cell types showed colony-forming ability and expressed typical MSCs markers, but differed in the levels of their expression. DF-MSCs proliferated faster, contained cells larger in diameter, exhibited a higher potential to form adipocytes and a lower potential to form chondrocytes and osteoblasts, compared with DP-MSCs. In contrast to DF-MSCs, DP-MSCs produced the transforming growth factor (TGF)-β and suppressed proliferation of peripheral blood mononuclear cells, which could be neutralized with anti-TGF-β antibody. The treatment with toll-like receptor 3 (TLR3) agonist augmented the suppressive potential of both cell types and potentiated TGF-β and interleukin-6 secretions by these cells. TLR4 agonist augmented the suppressive potential of DF-MSCs and increased TGF-β production, but abrogated the immunosuppressive activity of DP-MSCs by inhibiting TGF-β production and the expression of indolamine-2,3-dioxygenase-1. Some of these effects correlated with the higher expression of TLR3 and TLR4 by DP-MSCs compared with DF-MSCs. When transplanted in imunocompetent xenogenic host, both cell types induced formation of granulomatous tissue. In conclusion, our results suggest that dental MSCs are functionally different and each of these functions should be further explored in vivo before their specific biomedical applications.

  6. Identification of plant extracts with potential antidiabetic properties: effect on human peroxisome proliferator-activated receptor (PPAR), adipocyte differentiation and insulin-stimulated glucose uptake

    DEFF Research Database (Denmark)

    Christensen, Kathrine B; Minet, Ariane; Svenstrup, Henrik

    2009-01-01

    Thiazolidinediones (TZDs) are insulin sensitizing drugs used to treat type 2 diabetes. The primary target of the TZDs is the peroxisome proliferator-activated receptor (PPAR) gamma, a key regulator of adipogenesis and glucose homeostasis. Currently prescribed TZDs are full PPARgamma agonists, and...

  7. CERAPP: Collaborative Estrogen Receptor Activity Prediction Project

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    U.S. Environmental Protection Agency — Data from a large-scale modeling project called CERAPP (Collaborative Estrogen Receptor Activity Prediction Project) demonstrating using predictive computational...

  8. Chapter 8. Activation mechanisms of chemokine receptors

    DEFF Research Database (Denmark)

    Jensen, Pia C; Rosenkilde, Mette M

    2009-01-01

    binding. Attempts to unravel the activation mechanism of 7TM receptors have led to the conclusion that activation involves movements of the transmembrane segments VI and VII in particular, as recently gathered in the Global Toggle Switch Model. However, to understand the activation mechanism completely......, more research has to be done in this field. Chemokine receptors are interesting tools in this matter. First, the chemokine system has a high degree of promiscuity that allows several chemokines to target one receptor in different ways, as well as a single chemokine ligand to target several receptors...

  9. Receptor binding properties and antinociceptive effects of chimeric peptides consisting of a micro-opioid receptor agonist and an ORL1 receptor antagonist.

    Science.gov (United States)

    Kawano, Susumu; Ito, Risa; Nishiyama, Miharu; Kubo, Mai; Matsushima, Tomoko; Minamisawa, Motoko; Ambo, Akihiro; Sasaki, Yusuke

    2007-07-01

    Receptor binding properties and antinociceptive activities of chimeric peptides linked by spacers were investigated. The peptides consisted of the micro-opioid receptor ligand dermorphin (Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH(2)) or its analog YRFB (Tyr-D-Arg-Phe-betaAla-NH(2)) linked to the ORL1 receptor ligand Ac-Arg-Tyr-Tyr-Arg-Ile-Lys-NH(2) (Ac-RYYRIK-NH(2)). All chimeric peptides were found to possess high receptor binding affinities for both micro-opioid and ORL1 receptors in mouse brain membranes although their binding affinities for both receptors in spinal membranes were significantly lower. Among them, chimeric peptide 2, which consists of dermorphin and Ac-RYYRIK-NH(2) connected by a long spacer, had the highest binding affinity towards both receptors. In the tail-flick test following intrathecal (i.t.) administration to mice, all chimeric peptides showed potent and dose-dependent antinociceptive activities with an ED(50) of 1.34-4.51 (pmol/mouse), nearly comparable to dermorphin alone (ED(50); 1.08 pmol/mouse). In contrast to their micro-opioid receptor binding profiles, intracerebroventricular (i.c.v.) administration of the chimeric peptides resulted in much less potent antinociceptive activity (ED(50) 5.55-100peptides, and the regulation of mu-opioid receptor-mediated antinociception in brain. The present chimeric peptides may be useful as pharmacological tools for studies on micro-opioid receptor/ORL1 receptor heterodimers.

  10. Signaling properties and pharmacological analysis of two sulfakinin receptors from the red flour beetle, Tribolium castaneum.

    Directory of Open Access Journals (Sweden)

    Sven Zels

    Full Text Available Sulfakinin is an insect neuropeptide that constitutes an important component of the complex network of hormonal and neural factors that regulate feeding and digestion. The key modulating functions of sulfakinin are mediated by binding and signaling via G-protein coupled receptors. Although a substantial amount of functional data have already been reported on sulfakinins in different insect species, only little information is known regarding the properties of their respective receptors. In this study, we report on the molecular cloning, functional expression and characterization of two sulfakinin receptors in the red flour beetle, Tribolium castaneum. Both receptor open reading frames show extensive sequence similarity with annotated sulfakinin receptors from other insects. Comparison of the sulfakinin receptor sequences with homologous vertebrate cholecystokinin receptors reveals crucial conserved regions for ligand binding and receptor activation. Quantitative reverse transcriptase PCR shows that transcripts of both receptors are primarily expressed in the central nervous system of the beetle. Pharmacological characterization using 29 different peptide ligands clarified the essential requirements for efficient activation of these sulfakinin receptors. Analysis of the signaling pathway in multiple cell lines disclosed that the sulfakinin receptors of T. castaneum can stimulate both the Ca²⁺ and cyclic AMP second messenger pathways. This in depth characterization of two insect sulfakinin receptors may provide useful leads for the further development of receptor ligands with a potential applicability in pest control and crop protection.

  11. Signaling properties and pharmacological analysis of two sulfakinin receptors from the red flour beetle, Tribolium castaneum.

    Science.gov (United States)

    Zels, Sven; Verlinden, Heleen; Dillen, Senne; Vleugels, Rut; Nachman, Ronald J; Vanden Broeck, Jozef

    2014-01-01

    Sulfakinin is an insect neuropeptide that constitutes an important component of the complex network of hormonal and neural factors that regulate feeding and digestion. The key modulating functions of sulfakinin are mediated by binding and signaling via G-protein coupled receptors. Although a substantial amount of functional data have already been reported on sulfakinins in different insect species, only little information is known regarding the properties of their respective receptors. In this study, we report on the molecular cloning, functional expression and characterization of two sulfakinin receptors in the red flour beetle, Tribolium castaneum. Both receptor open reading frames show extensive sequence similarity with annotated sulfakinin receptors from other insects. Comparison of the sulfakinin receptor sequences with homologous vertebrate cholecystokinin receptors reveals crucial conserved regions for ligand binding and receptor activation. Quantitative reverse transcriptase PCR shows that transcripts of both receptors are primarily expressed in the central nervous system of the beetle. Pharmacological characterization using 29 different peptide ligands clarified the essential requirements for efficient activation of these sulfakinin receptors. Analysis of the signaling pathway in multiple cell lines disclosed that the sulfakinin receptors of T. castaneum can stimulate both the Ca²⁺ and cyclic AMP second messenger pathways. This in depth characterization of two insect sulfakinin receptors may provide useful leads for the further development of receptor ligands with a potential applicability in pest control and crop protection.

  12. Androgen insensitivity syndrome: gonadal androgen receptor activity

    International Nuclear Information System (INIS)

    Coulam, C.B.; Graham, M.L.; Spelsberg, T.C.

    1984-01-01

    To determine whether abnormalities of the androgen receptor previously observed in skin fibroblasts from patients with androgen insensitivity syndrome also occur in the gonads of affected individuals, androgen receptor activity in the gonads of a patient with testicular feminization syndrome was investigated. Using conditions for optimal recovery of androgen receptor from human testes established by previous studies, we detected the presence of a high-affinity (dissociation constant . 3.2 X 10(-10) mol/L), low-capacity (4.2 X 10(-12) mol/mg DNA), androgen-binding protein when tritium-labeled R1881 was incubated at 4 degrees C with nuclear extracts from the gonads of control patients or from a patient with testicular feminization syndrome but not when incubated at 37 degrees C. Thus this patient has an androgen receptor with a temperature lability similar to that of receptors from normal persons

  13. Pharmacological characterization of receptor-activity-modifying proteins (RAMPs) and the human calcitonin receptor.

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    Armour, S L; Foord, S; Kenakin, T; Chen, W J

    1999-12-01

    Receptor-activity-modifying proteins (RAMPs) are a family of single transmembrane domain proteins shown to be important for the transport and ligand specificity of the calcitonin gene-related peptide (CGRP) receptor. In this report, we describe the analysis of pharmacological properties of the human calcitonin receptor (hCTR) coexpressed with different RAMPs with the use of the Xenopus laevis melanophore expression system. We show that coexpression of RAMP3 with human calcitonin receptor changed the relative potency of hCTR to human calcitonin (hCAL) and rat amylin. RAMP1 and RAMP2, in contrast, had little effect on the change of hCTR potency to hCAL or rat amylin. When coexpressed with RAMP3, hCTR reversed the relative potency by a 3.5-fold loss in sensitivity to hCAL and a 19-fold increase in sensitivity to rat amylin. AC66, an inverse agonist, produced apparent simple competitive antagonism of hCAL and rat amylin, as indicated by linear Schild regressions. The potency of AC66 was changed in the blockade of rat amylin but not hCAL responses with RAMP3 coexpression. The mean pK(B) for AC66 to hCAL was 9.4 +/- 0.3 without RAMP3 and 9.45 +/- 0.07 with RAMP3. For the antagonism of AC66 to rat amylin, the pK(B) was 9.25 +/- 0.15 without RAMP3 and 8.2 +/- 0.35 with RAMP3. The finding suggests that RAMP3 might modify the active states of calcitonin receptor in such a way as to create a new receptor phenotype that is "amylin-like." Irrespective of the physiological association of the new receptor species, the finding that a coexpressed membrane protein can completely change agonist and antagonist affinities for a receptor raises implications for screening in recombinant receptor systems.

  14. Neurokinin-1 receptor activation in globus pallidus

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    Lei Chen

    2009-10-01

    Full Text Available The undecapeptide substance P has been demonstrated to modulate neuronal activity in a number of brain regions by acting on neurokinin-1 receptors. Anatomical studies revealed a moderate level of neurokinin-1 receptor in rat globus pallidus. To determine the electrophysiological effects of neurokinin-1 receptor activation in globus pallidus, whole-cell patch-clamp recordings were performed in the present study. Under current-clamp recordings, neurokinin-1 receptor agonist, [Sar9, Met(O211] substance P (SM-SP at 1 μM, depolarized globus pallidus neurons and increased their firing rate. Consistently, SM-SP induced an inward current under voltage-clamp recording. The depolarization evoked by SM-SP persisted in the presence of tetrodotoxin, glutamate and GABA receptor antagonists, indicating its direct postsynaptic effects. The neurokinin-1 receptor antagonist, SR140333B, could block SM-SP-induced depolarization. Further experiments showed that suppression of potassium conductance was the predominant ionic mechanism of SM-SP-induced depolarization. To determine if neurokinin-1 receptor activation exerts any effects on GABAergic and glutamatergic neurotransmission, the action of SM-SP on synaptic currents was studied. SM-SP significantly increased the frequency of spontaneous inhibitory postsynaptic currents, but only induced a transient increase in the frequency of miniature inhibitory postsynaptic currents. No change was observed in both spontaneous and miniature excitatory postsynaptic currents. Based on the direct excitatory effects of SM-SP on pallidal neurons, we hypothesize that neurokinin-1 receptor activation in globus pallidus may be involved in the beneficial effect of substance P in Parkinson’s disease.

  15. Opportunistic activation of TRP receptors by endogenous lipids: exploiting lipidomics to understand TRP receptor cellular communication.

    Science.gov (United States)

    Bradshaw, Heather B; Raboune, Siham; Hollis, Jennifer L

    2013-03-19

    Transient receptor potential channels (TRPs) form a large family of ubiquitous non-selective cation channels that function as cellular sensors and in many cases regulate intracellular calcium. Identification of the endogenous ligands that activate these TRP receptors is still under intense investigation with the majority of these channels still remaining "orphans." That these channels respond to a variety of external stimuli (e.g. plant-derived lipids, changes in temperature, and changes in pH) provides a framework for their abilities as cellular sensors, however, the mechanism of direct activation is still under much debate and research. In the cases where endogenous ligands (predominately lipids) have shown direct activation of a channel, multiple ligands have been shown to activate the same channel suggesting that these receptors are "promiscuous" in nature. Lipidomics of a growing class of endogenous lipids, N-acyl amides, the most famous of which is N-arachidonoyl ethanolamine (the endogenous cannabinoid, Anandamide) is providing a novel set of ligands that have been shown to activate some members of the TRP family and have the potential to deorphanize many more. Here it is argued that activation of TRPV receptors, a subset of the larger family of TRPs, by multiple endogenous lipids that are structurally analogous is a model system to drive our understanding that many TRP receptors are not promiscuous, but are more characteristically "opportunistic" in nature; exploiting the structural similarity and biosynthesis of a narrow range of analogous endogenous lipids. In addition, this manuscript will compare the activation properties of TRPC5 to the activity profile of an "orphan" lipid, N-palmitoyl glycine; further demonstrating that lipidomics aimed at expanding our knowledge of the family of N-acyl amides has the potential to provide novel avenues of research for TRP receptors. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Differences in both glycosylation and binding properties between rat and mouse liver prolactin receptors.

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    Lascols, O; Cherqui, G; Munier, A; Picard, J; Capeau, J

    1994-05-01

    To investigate whether glycanic chains of prolactin receptors (PRL-R) play a role in hormone binding activity, comparison was made of rat and mouse liver solubilized receptors with respect to both their affinity for the hormone and their glycosylation properties. As compared with rat receptors, mouse receptors exhibited a 2-fold higher affinity for human growth hormone (hGH), the hormone being bound by both tissues with a lactogenic specificity. Along with this increased affinity, mouse receptors had a 2 lower M(r) relative to rat receptors (62 kDa versus 64 kDa as measured on hGH cross-linked receptors). These differences could be ascribed to different glycosylation properties of the receptors from the two species, as supported by the followings. 1) After treatment with endoglycosidase F (endo F), rat and mouse PRL-R no longer exhibited any difference in their M(r) (54 kDa for both cross-linked receptors). 2) Neuraminidase treatment increased by 37% the binding of hGH to mouse receptors, but was ineffective on the hormone-binding to rat receptors. Conversely, wheat germ agglutinin (WGA), another sialic acid specific probe, decreased hGH binding to rat receptors by 25%, but had no effect on this process for mouse ones. 3) Marked differences were observed in the recoveries of rat and mouse hormone-receptor (HR) complexes from ricin-1- (RCA1-), concanavalin A- (ConA-) and WGA-immobilized lectins. These differences were reduced (RCA1 and ConA) or abolished (WGA) after rat and mouse receptor desialylation by neuraminidase, a treatment which decreased the M(r) of both receptors by 2 kDa. Taken together, these results strongly suggest that the PRL-R from rat and mouse liver contain biantennary N-linked oligosaccharidic chains with distinct type of sialylation, which may account for their differential hormone-binding affinities.

  17. The metabotropic glutamate receptors: structure, activation mechanism and pharmacology.

    Science.gov (United States)

    Pin, Jean-Philippe; Acher, Francine

    2002-06-01

    The metabotropic glutamate receptors are G-protein coupled receptors (GPCR) involved in the regulation of many synapses, including most glutamatergic fast excitatory synapses. Eight subtypes have been identified that can be classified into three groups. The molecular characterization of these receptors revealed proteins much more complex than any other GPCRs. They are composed of a Venus Flytrap (VFT) module where glutamate binds, connected to a heptahelical domain responsible for G-protein coupling. Recent data including the structure of the VFT module determined with and without glutamate, indicate that these receptors function as dimers. Moreover a number of intracellular proteins can regulate their targeting and transduction mechanism. Such structural features of mGlu receptors offer multiple possibilities for synthetic compounds to modulate their activity. In addition to agonists and competitive antagonists acting at the glutamate binding site, a number of non-competitive antagonists with inverse agonist activity, and positive allosteric modulators have been discovered. These later compounds share specific properties that make them good candidates for therapeutic applications. First, their non-amino acid structure makes them pass more easily the blood brain barrier. Second, they are much more selective than any other compound identified so far, being the first subtype selective molecules. Third, for the negative modulators, their non competitive mechanism of action makes them relatively unaffected by high concentrations of glutamate that may be present in disease states (e.g. stroke, epilepsy, neuropathic pain, etc.). Fourth, like the benzodiazepines acting at the GABA(A) receptors, the positive modulators offer a new way to increase the activity of these receptors in vivo, with a low risk of inducing their desensitization. The present review article focuses on the specific structural features of these receptors and highlights the various possibilities these

  18. Receptor activity-independent recruitment of βarrestin2 reveals specific signalling modes

    Science.gov (United States)

    Terrillon, Sonia; Bouvier, Michel

    2004-01-01

    The roles of βarrestins in regulating G protein coupling and receptor endocytosis following agonist stimulation of G protein-coupled receptors are well characterised. However, their ability to act on their own as direct modulators or activators of signalling remains poorly characterised. Here, βarrestin2 intrinsic signalling properties were assessed by forcing the recruitment of this accessory protein to vasopressin V1a or V2 receptors independently of agonist-promoted activation of the receptors. Such induction of a stable interaction with βarrestin2 initiated receptor endocytosis leading to intracellular accumulation of the βarrestin/receptor complexes. Interestingly, βarrestin2 association to a single receptor protomer was sufficient to elicit receptor dimer internalisation. In addition to recapitulating βarrestin2 classical actions on receptor trafficking, the receptor activity-independent recruitment of βarrestin2 activated the extracellular signal-regulated kinases. In the latter case, recruitment to the receptor itself was not required since kinase activation could be mediated by βarrestin2 translocation to the plasma membrane in the absence of any interacting receptor. These data demonstrate that βarrestin2 can act as a ‘bonafide' signalling molecule even in the absence of activated receptor. PMID:15385966

  19. Molecular, pharmacological, and signaling properties of octopamine receptors from honeybee (Apis mellifera) brain.

    Science.gov (United States)

    Balfanz, Sabine; Jordan, Nadine; Langenstück, Teresa; Breuer, Johanna; Bergmeier, Vera; Baumann, Arnd

    2014-04-01

    G protein-coupled receptors are important regulators of cellular signaling processes. Within the large family of rhodopsin-like receptors, those binding to biogenic amines form a discrete subgroup. Activation of biogenic amine receptors leads to transient changes of intracellular Ca²⁺-([Ca²⁺](i)) or 3',5'-cyclic adenosine monophosphate ([cAMP](i)) concentrations. Both second messengers modulate cellular signaling processes and thereby contribute to long-lasting behavioral effects in an organism. In vivo pharmacology has helped to reveal the functional effects of different biogenic amines in honeybees. The phenolamine octopamine is an important modulator of behavior. Binding of octopamine to its receptors causes elevation of [Ca²⁺](i) or [cAMP](i). To date, only one honeybee octopamine receptor that induces Ca²⁺ signals has been molecularly and pharmacologically characterized. Here, we examined the pharmacological properties of four additional honeybee octopamine receptors. When heterologously expressed, all receptors induced cAMP production after binding to octopamine with EC₅₀(s) in the nanomolar range. Receptor activity was most efficiently blocked by mianserin, a substance with antidepressant activity in vertebrates. The rank order of inhibitory potency for potential receptor antagonists was very similar on all four honeybee receptors with mianserin > cyproheptadine > metoclopramide > chlorpromazine > phentolamine. The subroot of octopamine receptors activating adenylyl cyclases is the largest that has so far been characterized in arthropods, and it should now be possible to unravel the contribution of individual receptors to the physiology and behavior of honeybees. © 2013 International Society for Neurochemistry.

  20. Microsomal receptor for steroid hormones: functional implications for nuclear activity.

    Science.gov (United States)

    Muldoon, T G; Watson, G H; Evans, A C; Steinsapir, J

    1988-01-01

    Target tissues for steroid hormones are responsive by virtue of and to the extent of their content of functional intracellular receptors. Recent years have seen a shift in considerations of the cellular dynamics and distribution of these receptors, with current views favoring predominant intranuclear localization in the intact cell. This paper summarizes our analyses of the microsomal estrogen and androgen binding capability of rat uterine and ventral prostate tissue, respectively; these studies have revealed a set of high affinity sites that may act as a conduit for estrogen traversing the cell en route to the nucleus. These sites have many properties in common with cytosolic receptors, with the salient difference of a failure to activate to a more avid DNA-binding form under conditions which permit such activation of cytosolic receptors. The microsomal estrogen-binding proteins also have appreciable affinity for progesterone, another distinction from other known cellular estrogen receptor species. Various experimental approaches were employed to demonstrate that the microsomal receptors were not simply cytosol contaminants; the most convincing evidence is the recent successful separation of the cytosolic and microsomal forms by differential ammonium sulfate precipitation. Discrete subfractionation of subcellular components on successive sucrose gradients, with simultaneous assessments of binding capability and marker enzyme concentrations, indicates that the major portion of the binding is localized within the vesicles of the endoplasmic reticulum free of significant plasma membrane contamination. The microsomal receptors are readily solubilized by extraction with high- or low-salt-containing buffers or with steroid. The residual microsomes following such extraction have the characteristics of saturable acceptor sites for cytosolic estrogen-receptor complexes. The extent to which these sites will accept the cytosolic complexes is equal to the concentration of

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

    Science.gov (United States)

    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

  2. CERAPP: Collaborative estrogen receptor activity prediction project

    DEFF Research Database (Denmark)

    Mansouri, Kamel; Abdelaziz, Ahmed; Rybacka, Aleksandra

    2016-01-01

    ). Risk assessors need tools to prioritize chemicals for evaluation in costly in vivo tests, for instance, within the U.S. EPA Endocrine Disruptor Screening Program. oBjectives: We describe a large-scale modeling project called CERAPP (Collaborative Estrogen Receptor Activity Prediction Project...... States and Europe to predict ER activity of a common set of 32,464 chemical structures. Quantitative structure-activity relationship models and docking approaches were employed, mostly using a common training set of 1,677 chemical structures provided by the U.S. EPA, to build a total of 40 categorical......: Individual model scores ranged from 0.69 to 0.85, showing high prediction reliabilities. Out of the 32,464 chemicals, the consensus model predicted 4,001 chemicals (12.3%) as high priority actives and 6,742 potential actives (20.8%) to be considered for further testing. conclusion: This project demonstrated...

  3. Native CB1 receptor affinity, intrinsic activity and accumbens shell dopamine stimulant properties of third generation SPICE/K2 cannabinoids: BB-22, 5F-PB-22, 5F-AKB-48 and STS-135.

    Science.gov (United States)

    De Luca, Maria Antonietta; Castelli, M Paola; Loi, Barbara; Porcu, Alessandra; Martorelli, Mariella; Miliano, Cristina; Kellett, Kathryn; Davidson, Colin; Stair, Jacqueline L; Schifano, Fabrizio; Di Chiara, Gaetano

    2016-06-01

    In order to investigate the in vivo dopamine (DA) stimulant properties of selected 3rd generation Spice/K2 cannabinoids, BB-22, 5F-PB-22, 5F-AKB-48 and STS-135, their in vitro affinity and agonist potency at native rat and mice CB1 receptors was studied. The compounds bind with high affinity to CB1 receptors in rat cerebral cortex homogenates and stimulate CB1-induced [(35)S]GTPγS binding with high potency and efficacy. BB-22 and 5F-PB-22 showed the lowest Ki of binding to CB1 receptors (0.11 and 0.13 nM), i.e., 30 and 26 times lower respectively than that of JWH-018 (3.38 nM), and a potency (EC50, 2.9 and 3.7 nM, respectively) and efficacy (Emax, 217% and 203%, respectively) as CB1 agonists higher than JWH-018 (EC50, 20.2 nM; Emax, 163%). 5F-AKB-48 and STS-135 had higher Ki for CB1 binding, higher EC50 and lower Emax as CB1 agonists than BB-22 and 5F-PB-22 but still comparatively more favourable than JWH-018. The agonist properties of all the compounds were abolished or drastically reduced by the CB1 antagonist/inverse agonist AM251 (0.1 μM). No activation of G-protein was observed in CB1-KO mice. BB-22 (0.003-0.01 mg/kg i.v.) increased dialysate DA in the accumbens shell but not in the core or in the medial prefrontal cortex, with a bell shaped dose-response curve and an effect at 0.01 mg/kg and a biphasic time-course. Systemic AM251 (1.0 mg/kg i.p.) completely prevented the stimulant effect of BB-22 on dialysate DA in the NAc shell. All the other compounds increased dialysate DA in the NAc shell at doses consistent with their in vitro affinity for CB1 receptors (5F-PB-22, 0.01 mg/kg; 5F-AKB-48, 0.1 mg/kg; STS-135, 0.15 mg/kg i.v.). 3rd generation cannabinoids can be even more potent and super-high CB1 receptor agonists compared to JWH-018. Future research will try to establish if these properties can explain the high toxicity and lethality associated with these compounds. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Structural basis for activation of G-protein-coupled receptors

    DEFF Research Database (Denmark)

    Gether, Ulrik; Asmar, Fazila; Meinild, Anne Kristine

    2002-01-01

    into conformational changes accompanying GPCR activation and the underlying molecular mechanism governing transition of the receptor between its active and inactive states. Using the beta2-adrenergic receptor as a model system we have obtained evidence for an evolutionary conserved activation mechanism where...... changes and receptor activation. At the current stage we are exploring the possibility of reaching this goal by direct in situ labeling of the beta2-adrenergic receptor in Xenopus laevis oocytes with conformationally sensitive fluorescent probes and parallel detection of receptor activation by co...

  5. Mouse Clr-g, a ligand for NK cell activation receptor NKR-P1F: crystal structure and biophysical properties

    Czech Academy of Sciences Publication Activity Database

    Skálová, Tereza; Kotýnková, Kristýna; Dušková, Jarmila; Hašek, Jindřich; Koval, Tomáš; Kolenko, Petr; Novák, P.; Man, Petr; Hanč, Pavel; Vaněk, Ondřej; Bezouška, K.; Dohnálek, Jan

    2012-01-01

    Roč. 189, č. 10 (2012), s. 4881-4889 ISSN 0022-1767 R&D Projects: GA AV ČR KJB101120805; GA ČR GAP302/11/0855; GA ČR GD305/09/H008; GA ČR GA305/07/1073; GA ČR(CZ) GAP207/10/1040; GA MŠk EE2.3.30.0029; GA ČR GA303/09/0477 EU Projects: European Commission(XE) 31220 - SPINE2-COMPLEXES Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z50200510 Institutional support: RVO:61389013 ; RVO:61388971 Keywords : Clr-g * C-type lectin like fold * NK receptor Subject RIV: CE - Biochemistry; EC - Immunology (MBU-M) Impact factor: 5.520, year: 2012

  6. Mycobacterium tuberculosis cAMP Receptor Protein (Rv3676) Differs from the Escherichia coli Paradigm in Its cAMP Binding and DNA Binding Properties and Transcription Activation Properties*

    Science.gov (United States)

    Stapleton, Melanie; Haq, Ihtshamul; Hunt, Debbie M.; Arnvig, Kristine B.; Artymiuk, Peter J.; Buxton, Roger S.; Green, Jeffrey

    2010-01-01

    The pathogen Mycobacterium tuberculosis produces a burst of cAMP upon infection of macrophages. Bacterial cyclic AMP receptor proteins (CRP) are transcription factors that respond to cAMP by binding at target promoters when cAMP concentrations increase. Rv3676 (CRPMt) is a CRP family protein that regulates expression of genes (rpfA and whiB1) that are potentially involved in M. tuberculosis persistence and/or emergence from the dormant state. Here, the CRPMt homodimer is shown to bind two molecules of cAMP (one per protomer) at noninteracting sites. Furthermore, cAMP binding by CRPMt was relatively weak, entropy driven, and resulted in a relatively small enhancement in DNA binding. Tandem CRPMt-binding sites (CRP1 at −58.5 and CRP2 at −37.5) were identified at the whiB1 promoter (PwhiB1). In vitro transcription reactions showed that CRP1 is an activating site and that CRP2, which was only occupied in the presence of cAMP or at high CRPMt concentrations in the absence of cAMP, is a repressing site. Binding of CRPMt to CRP1 was not essential for open complex formation but was required for transcription activation. Thus, these data suggest that binding of CRPMt to the PwhiB1 CRP1 site activates transcription at a step after open complex formation. In contrast, high cAMP concentrations allowed occupation of both CRP1 and CRP2 sites, resulting in inhibition of open complex formation. Thus, M. tuberculosis CRP has evolved several distinct characteristics, compared with the Escherichia coli CRP paradigm, to allow it to regulate gene expression against a background of high concentrations of cAMP. PMID:20028978

  7. Mechanoreceptor afferent activity compared with receptor field dimensions and pressure changes in feline urinary bladder.

    Science.gov (United States)

    Downie, J W; Armour, J A

    1992-11-01

    The relationship between vesical mechanoreceptor field dimensions and afferent nerve activity recorded in pelvic plexus nerve filaments was examined in chloralose-anesthetized cats. Orthogonal receptor field dimensions were monitored with piezoelectric ultrasonic crystals. Reflexly generated bladder contractile activity made measurements difficult, therefore data were collected from cats subjected to actual sacral rhizotomy. Afferent activity was episodic and was initiated at different pressure and receptor field dimension thresholds. Maximum afferent activity did not correlate with maximum volume or pressure. Furthermore, activity was not linearly related to intravesical pressure, receptor field dimensions, or calculated wall tension. Pressure-length hysteresis of the receptor fields occurred. The responses of identified afferent units and their associated receptor field dimensions to brief contractions elicited by the ganglion stimulant 1,1-dimethyl-4-phenylpiperazinium iodide (2.5-20 micrograms i.a.), studied under constant volume or constant pressure conditions, are compatible with bladder mechanoreceptors behaving as tension receptors. Because activity generated by bladder mechanoreceptors did not correlate in a simple fashion with intravesical pressure or receptor field dimensions, it is concluded that such receptors are influenced by the viscoelastic properties of the bladder wall. Furthermore, as a result of the heterogeneity of the bladder wall, receptor field tension appears to offer a more precise relationship with the activity of bladder wall mechanoreceptors than does intravesical pressure.

  8. Protease activated receptors (PARS) mediation in gyroxin biological activity

    International Nuclear Information System (INIS)

    Silva, Jose Alberto Alves da

    2009-01-01

    Gyroxin is a serine protease enzyme from the South American rattlesnake (Crotalus durissus terrificus) venom; it is only partially characterized and has multiple activities. Gyroxin induces blood coagulation, blood pressure decrease and a neurotoxic behavior named barrel rotation. The mechanisms involved in this neurotoxic activity are not known. Whereas gyroxin is a member of enzymes with high potential to become a new drug with clinical applications such as thrombin, batroxobin, ancrod, tripsyn and kalicrein, it is important to find out how gyroxin works. The analysis on agarose gel electrophoresis and circular dichroism confirmed the molecules' integrity and purity. The gyroxin intravenous administration in mice proved its neurotoxicity (barrel rotation). In vivo studies employing intravital microscopy proved that gyroxin induces vasodilation with the participation of protease activated receptors (PARs), nitric oxide and Na+K+ATPase. The leukocytes' adherence and rolling counting indicated that gyroxin has no pro inflammatory activity. Gyroxin induced platelet aggregation, which was blocked by inhibitors of PAR1 and PAR4 receptors (SCH 79797 and tcY-NH 2 , respectively). Finally, it was proved that the gyroxin temporarily alter the permeability of the blood brain barrier (BBB). Our study has shown that both the protease-activated receptors and nitric oxide are mediators involved in the biological activities of gyroxin. (author)

  9. Material properties in complement activation

    DEFF Research Database (Denmark)

    Moghimi, S. Moein; Andersen, Alina Joukainen; Ahmadvand, Davoud

    2011-01-01

    activation differently and through different sensing molecules and initiation pathways. The importance of material properties in triggering complement is considered and mechanistic aspects discussed. Mechanistic understanding of complement events could provide rational approaches for improved material design...

  10. Retinoid X receptor and peroxisome proliferator-activated receptor activate an estrogen responsive gene independent of the estrogen receptor.

    Science.gov (United States)

    Nuñez, S B; Medin, J A; Braissant, O; Kemp, L; Wahli, W; Ozato, K; Segars, J H

    1997-03-14

    Estrogen receptors regulate transcription of genes essential for sexual development and reproductive function. Since the retinoid X receptor (RXR) is able to modulate estrogen responsive genes and both 9-cis RA and fatty acids influenced development of estrogen responsive tumors, we hypothesized that estrogen responsive genes might be modulated by RXR and the fatty acid receptor (peroxisome proliferator-activated receptor, PPAR). To test this hypothesis, transfection assays in CV-1 cells were performed with an estrogen response element (ERE) coupled to a luciferase reporter construct. Addition of expression vectors for RXR and PPAR resulted in an 11-fold increase in luciferase activity in the presence of 9-cis RA. Furthermore, mobility shift assays demonstrated binding of RXR and PPAR to the vitellogenin A2-ERE and an ERE in the oxytocin promoter. Methylation interference assays demonstrated that specific guanine residues required for RXR/PPAR binding to the ERE were similar to residues required for ER binding. Moreover, RXR domain-deleted constructs in transfection assays showed that activation required RXR since an RXR delta AF-2 mutant completely abrogated reporter activity. Oligoprecipitation binding studies with biotinylated ERE and (35)S-labeled in vitro translated RXR constructs confirmed binding of delta AF-2 RXR mutant to the ERE in the presence of baculovirus-expressed PPAR. Finally, in situ hybridization confirmed RXR and PPAR mRNA expression in estrogen responsive tissues. Collectively, these data suggest that RXR and PPAR are present in reproductive tissues, are capable of activating estrogen responsive genes and suggest that the mechanism of activation may involve direct binding of the receptors to estrogen response elements.

  11. Signaling Properties of Chemerin Receptors CMKLR1, GPR1 and CCRL2.

    Science.gov (United States)

    De Henau, Olivier; Degroot, Gaetan-Nagim; Imbault, Virginie; Robert, Virginie; De Poorter, Cédric; Mcheik, Saria; Galés, Céline; Parmentier, Marc; Springael, Jean-Yves

    2016-01-01

    Chemerin is a small chemotactic protein originally identified as the natural ligand of CMKLR1. More recently, two other receptors, GPR1 and CCRL2, have been reported to bind chemerin but their functional relevance remains poorly understood. In this study, we compared the binding and signaling properties of the three human chemerin receptors and showed differences in mode of chemerin binding and receptor signaling. Chemerin binds to all three receptors with low nanomolar affinities. However, the contribution of the chemerin C-terminus to binding efficiency varies greatly amongst receptors. By using BRET-based biosensors monitoring the activation of various G proteins, we showed that binding of chemerin and the chemerin 9 nonapeptide (149YFPGQFAFS157) to CMKLR1 activates the three Gαi subtypes (Gαi1, Gαi2 and Gαi3) and the two Gαo isoforms (Gαoa and Gαob) with potencies correlated to binding affinities. In contrast, no significant activation of G proteins was detected upon binding of chemerin to GPR1 or CCRL2. Binding of chemerin and the chemerin 9 peptide also induced the recruitment of β-arrestin1 and 2 to CMKLR1 and GPR1, though to various degree, but not to CCRL2. However, the propensity of chemerin 9 to activate β-arrestins relative to chemerin is higher when bound to GPR1. Finally, we showed that binding of chemerin to CMKLR1 and GPR1 promotes also the internalization of the two receptors and the phosphorylation of ERK1/2 MAP kinases, although with a different efficiency, and that phosphorylation of ERK1/2 requires both Gαi/o and β-arrestin2 activation but not β-arrestin1. Collectively, these data support a model in which each chemerin receptor displays selective signaling properties.

  12. Increased amphetamine-induced locomotor activity, sensitization, and accumbal dopamine release in M5 muscarinic receptor knockout mice

    DEFF Research Database (Denmark)

    Schmidt, Lene S; Miller, Anthony D; Lester, Deranda B

    2010-01-01

    showed that M(5) receptor knockout (M (5) (-/-) ) mice are less sensitive to the reinforcing properties of addictive drugs. MATERIALS AND METHODS: Here, we investigate the role of M(5) receptors in the effects of amphetamine and cocaine on locomotor activity, locomotor sensitization, and dopamine release......-induced hyperactivity and dopamine release as well as amphetamine sensitization are enhanced in mice lacking the M(5) receptor. These results support the concept that the M(5) receptor modulates effects of addictive drugs....

  13. Properties of GluR3 receptors tagged with GFP at the amino or carboxyl terminus.

    Science.gov (United States)

    Limon, Agenor; Reyes-Ruiz, Jorge Mauricio; Eusebi, Fabrizio; Miledi, Ricardo

    2007-09-25

    Anatomical visualization of neurotransmitter receptor localization is facilitated by tagging receptors, but this process can alter their functional properties. We have evaluated the distribution and properties of WT glutamate receptor 3 (GluR3) alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (WT GluR3) and two receptors in which GFP was tagged to the amino terminus (GFP-GluR3) or to the carboxyl terminus (GluR3-GFP). Although the fluorescence in Xenopus oocytes was stronger in the vegetal hemisphere because of localization of internal structures (probable sites of production, storage or recycling of receptors), the insertion of receptors into the plasma membrane was polarized to the animal hemisphere. The fluorescence intensity of oocytes injected with GluR3-GFP RNA was approximately double that of oocytes injected with GFP-GluR3 RNA. Accordingly, GluR3-GFP oocytes generated larger kainate-induced currents than GFP-GluR3 oocytes, with similar EC(50) values. Currents elicited by glutamate, or AMPA coapplied with cyclothiazide, were also larger in GluR3-GFP oocytes. The glutamate- to kainate-current amplitude ratios differed, with GluR3-GFP being activated more efficiently by glutamate than the WT or GFP-GluR3 receptors. This pattern correlates with the slower decay of glutamate-induced currents generated by GluR3-GFP receptors. These changes were not observed when GFP was tagged to the amino terminus, and these receptors behaved like the WT. The antagonistic effects of 6-nitro-7-sulfamoylbenzo[f]quinoxaline-2,3-dione (NBQX) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) were not altered in any of the tagged receptors. We conclude that GFP is a useful and convenient tag for visualizing these proteins. However, the effects of different sites of tag insertion on receptor characteristics must be taken into account in assessing the roles played by these receptor proteins.

  14. Recruitment of activation receptors at inhibitory NK cell immune synapses.

    Directory of Open Access Journals (Sweden)

    Nicolas Schleinitz

    2008-09-01

    Full Text Available Natural killer (NK cell activation receptors accumulate by an actin-dependent process at cytotoxic immune synapses where they provide synergistic signals that trigger NK cell effector functions. In contrast, NK cell inhibitory receptors, including members of the MHC class I-specific killer cell Ig-like receptor (KIR family, accumulate at inhibitory immune synapses, block actin dynamics, and prevent actin-dependent phosphorylation of activation receptors. Therefore, one would predict inhibition of actin-dependent accumulation of activation receptors when inhibitory receptors are engaged. By confocal imaging of primary human NK cells in contact with target cells expressing physiological ligands of NK cell receptors, we show here that this prediction is incorrect. Target cells included a human cell line and transfected Drosophila insect cells that expressed ligands of NK cell activation receptors in combination with an MHC class I ligand of inhibitory KIR. The two NK cell activation receptors CD2 and 2B4 accumulated and co-localized with KIR at inhibitory immune synapses. In fact, KIR promoted CD2 and 2B4 clustering, as CD2 and 2B4 accumulated more efficiently at inhibitory synapses. In contrast, accumulation of KIR and of activation receptors at inhibitory synapses correlated with reduced density of the integrin LFA-1. These results imply that inhibitory KIR does not prevent CD2 and 2B4 signaling by blocking their accumulation at NK cell immune synapses, but by blocking their ability to signal within inhibitory synapses.

  15. The WSXWS motif in cytokine receptors is a molecular switch involved in receptor activation

    DEFF Research Database (Denmark)

    Dagil, Robert; Knudsen, Maiken J.; Olsen, Johan Gotthardt

    2012-01-01

    The prolactin receptor (PRLR) is activated by binding of prolactin in a 2:1 complex, but the activation mechanism is poorly understood. PRLR has a conserved WSXWS motif generic to cytokine class I receptors. We have determined the nuclear magnetic resonance solution structure of the membrane...

  16. Regulated internalization of NMDA receptors drives PKD1-mediated suppression of the activity of residual cell-surface NMDA receptors.

    Science.gov (United States)

    Fang, Xiao-Qian; Qiao, Haifa; Groveman, Bradley R; Feng, Shuang; Pflueger, Melissa; Xin, Wen-Kuan; Ali, Mohammad K; Lin, Shuang-Xiu; Xu, Jindong; Duclot, Florian; Kabbaj, Mohamed; Wang, Wei; Ding, Xin-Sheng; Santiago-Sim, Teresa; Jiang, Xing-Hong; Salter, Michael W; Yu, Xian-Min

    2015-11-19

    Constitutive and regulated internalization of cell surface proteins has been extensively investigated. The regulated internalization has been characterized as a principal mechanism for removing cell-surface receptors from the plasma membrane, and signaling to downstream targets of receptors. However, so far it is still not known whether the functional properties of remaining (non-internalized) receptor/channels may be regulated by internalization of the same class of receptor/channels. The N-methyl-D-aspartate receptor (NMDAR) is a principal subtype of glutamate-gated ion channel and plays key roles in neuronal plasticity and memory functions. NMDARs are well-known to undergo two types of regulated internalization - homologous and heterologous, which can be induced by high NMDA/glycine and DHPG, respectively. In the present work, we investigated effects of regulated NMDAR internalization on the activity of residual cell-surface NMDARs and neuronal functions. In electrophysiological experiments we discovered that the regulated internalization of NMDARs not only reduced the number of cell surface NMDARs but also caused an inhibition of the activity of remaining (non-internalized) surface NMDARs. In biochemical experiments we identified that this functional inhibition of remaining surface NMDARs was mediated by increased serine phosphorylation of surface NMDARs, resulting from the activation of protein kinase D1 (PKD1). Knockdown of PKD1 did not affect NMDAR internalization but prevented the phosphorylation and inhibition of remaining surface NMDARs and NMDAR-mediated synaptic functions. These data demonstrate a novel concept that regulated internalization of cell surface NMDARs not only reduces the number of NMDARs on the cell surface but also causes an inhibition of the activity of remaining surface NMDARs through intracellular signaling pathway(s). Furthermore, modulating the activity of remaining surface receptors may be an effective approach for treating receptor

  17. Activation of glucocorticoid receptors increases 5-HT2A receptor levels

    DEFF Research Database (Denmark)

    Trajkovska, Viktorija; Kirkegaard, Lisbeth; Krey, Gesa

    2009-01-01

    an effect of GR activation on 5-HT2A levels, mature organotypic hippocampal cultures were exposed to corticosterone with or without GR antagonist mifepristone and mineralocorticoid receptor (MR) antagonist spironolactone. In GR under-expressing mice, hippocampal 5-HT2A receptor protein levels were decreased......Major depression is associated with both dysregulation of the hypothalamic pituitary adrenal axis and serotonergic deficiency, not the least of the 5-HT2A receptor. However, how these phenomena are linked to each other, and whether a low 5-HT2A receptor level is a state or a trait marker...... of depression is unknown. In mice with altered glucocorticoid receptor (GR) expression we investigated 5-HT2A receptor levels by Western blot and 3H-MDL100907 receptor binding. Serotonin fibre density was analyzed by stereological quantification of serotonin transporter immunopositive fibers. To establish...

  18. Modulating Estrogen Receptor-related ReceptorActivity Inhibits Cell Proliferation*

    OpenAIRE

    Bianco, Stéphanie; Lanvin, Olivia; Tribollet, Violaine; Macari, Claire; North, Sophie; Vanacker, Jean-Marc

    2009-01-01

    High expression of the estrogen receptor-related receptor (ERR)-α in human tumors is correlated to a poor prognosis, suggesting an involvement of the receptor in cell proliferation. In this study, we show that a synthetic compound (XCT790) that modulates the activity of ERRα reduces the proliferation of various cell lines and blocks the G1/S transition of the cell cycle in an ERR...

  19. The Orphan Nuclear Receptor TR4 Is a Vitamin A-activated Nuclear Receptor

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X. Edward; Suino-Powell, Kelly M.; Xu, Yong; Chan, Cee-Wah; Tanabe, Osamu; Kruse, Schoen W.; Reynolds, Ross; Engel, James Douglas; Xu, H. Eric (Michigan-Med); (Van Andel)

    2015-11-30

    Testicular receptors 2 and 4 (TR2/4) constitute a subgroup of orphan nuclear receptors that play important roles in spermatogenesis, lipid and lipoprotein regulation, and the development of the central nervous system. Currently, little is known about the structural features and the ligand regulation of these receptors. Here we report the crystal structure of the ligand-free TR4 ligand binding domain, which reveals an autorepressed conformation. The ligand binding pocket of TR4 is filled by the C-terminal half of helix 10, and the cofactor binding site is occupied by the AF-2 helix, thus preventing ligand-independent activation of the receptor. However, TR4 exhibits constitutive transcriptional activity on multiple promoters, which can be further potentiated by nuclear receptor coactivators. Mutations designed to disrupt cofactor binding, dimerization, or ligand binding substantially reduce the transcriptional activity of this receptor. Importantly, both retinol and retinoic acid are able to promote TR4 to recruit coactivators and to activate a TR4-regulated reporter. These findings demonstrate that TR4 is a ligand-regulated nuclear receptor and suggest that retinoids might have a much wider regulatory role via activation of orphan receptors such as TR4.

  20. Family C 7TM receptor dimerization and activation

    DEFF Research Database (Denmark)

    Bonde, Marie Mi; Sheikh, Søren P; Hansen, Jakob Lerche

    2006-01-01

    The family C seven transmembrane (7TM) receptors constitutes a small and especially well characterized subfamily of the large 7TM receptor superfamily. Approximately 50% of current prescription drugs target 7TM receptors, this biologically important family represents the largest class of drug...... to be fully defined. This review presents the biochemical support for family C 7TM receptor dimerization and discusses its importance for receptor biosynthesis, surface expression, ligand binding and activation, since lessons learnt here may well be applicable to the whole superfamily of 7TM receptors.......-targets today. It is well established that family C 7TM receptors form homo- or hetero-dimers on the cell surface of living cells. The large extra-cellular domains (ECD) have been crystallized as a dimer in the presence and absence of agonist. Upon agonist binding, the dimeric ECD undergoes large conformational...

  1. Structure-activity relationships of rosiglitazone for peroxisome proliferator-activated receptor gamma transrepression.

    Science.gov (United States)

    Toyota, Yosuke; Nomura, Sayaka; Makishima, Makoto; Hashimoto, Yuichi; Ishikawa, Minoru

    2017-06-15

    Anti-inflammatory effects of peroxisome proliferator-activated receptor gamma (PPRAγ) ligands are thought to be largely due to PPARγ-mediated transrepression. Thus, transrepression-selective PPARγ ligands without agonistic activity or with only partial agonistic activity should exhibit anti-inflammatory properties with reduced side effects. Here, we investigated the structure-activity relationships (SARs) of PPARγ agonist rosiglitazone, focusing on transrepression activity. Alkenic analogs showed slightly more potent transrepression with reduced efficacy of transactivating agonistic activity. Removal of the alkyl group on the nitrogen atom improved selectivity for transrepression over transactivation. Among the synthesized compounds, 3l exhibited stronger transrepressional activity (IC 50 : 14μM) and weaker agonistic efficacy (11%) than rosiglitazone or pioglitazone. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Interaction of chemokines with their receptors--from initial chemokine binding to receptor activating steps

    DEFF Research Database (Denmark)

    Thiele, Stefanie; Rosenkilde, Mette Marie

    2014-01-01

    and surveillance. Chemokines are a group of 8-12 kDa large peptides with a secondary structure consisting of a flexible N-terminus and a core-domain usually stabilized by two conserved disulfide bridges. They mainly interact with the extracellular domains of their cognate 7TM receptors. Affinityand activity......-contributing interactions are attributed to different domains and known to occur in two steps. Here, knowledge on chemokine and receptor domains involved in the first binding-step and the second activation-step is reviewed. A mechanism comprising at least two steps seems consistent; however, several intermediate...... interactions possibly occur, resulting in a multi-step process, as recently proposed for other 7TM receptors. Overall, the N-terminus of chemokine receptors is pivotal for binding of all chemokines. During receptor activation, differences between the two major chemokine subgroups occur, as CC-chemokines mainly...

  3. Phenobarbital indirectly activates the constitutive active androstane receptor (CAR) by inhibition of epidermal growth factor receptor signaling.

    Science.gov (United States)

    Mutoh, Shingo; Sobhany, Mack; Moore, Rick; Perera, Lalith; Pedersen, Lee; Sueyoshi, Tatsuya; Negishi, Masahiko

    2013-05-07

    Phenobarbital is a central nervous system depressant that also indirectly activates nuclear receptor constitutive active androstane receptor (CAR), which promotes drug and energy metabolism, as well as cell growth (and death), in the liver. We found that phenobarbital activated CAR by inhibiting epidermal growth factor receptor (EGFR) signaling. Phenobarbital bound to EGFR and potently inhibited the binding of EGF, which prevented the activation of EGFR. This abrogation of EGFR signaling induced the dephosphorylation of receptor for activated C kinase 1 (RACK1) at Tyr(52), which then promoted the dephosphorylation of CAR at Thr(38) by the catalytic core subunit of protein phosphatase 2A. The findings demonstrated that the phenobarbital-induced mechanism of CAR dephosphorylation and activation is mediated through its direct interaction with and inhibition of EGFR.

  4. The endothelial protein C receptor and activated protein C play a limited role in host defense during experimental tuberculosis

    NARCIS (Netherlands)

    Kager, Liesbeth M.; Roelofs, Joris J. T. H.; de Vos, Alex F.; Wieland, Catharina W.; Schouten, Marcel; Meijers, Joost C. M.; Isermann, Berend; van't Veer, Cornelis; Esmon, Charles T.; van der Poll, Tom

    2013-01-01

    The protein C (PC) system is an important regulator of both coagulation and inflammation. Activated PC (APC), together with its receptor the endothelial protein C receptor (EPCR), has anticoagulant and anti-inflammatory properties. During tuberculosis (TB), a devastating chronic pulmonary disease

  5. Differential trafficking of AMPA receptors following activation of NMDA receptors and mGluRs

    Directory of Open Access Journals (Sweden)

    Sanderson Thomas M

    2011-07-01

    Full Text Available Abstract The removal of AMPA receptors from synapses is a major component of long-term depression (LTD. How this occurs, however, is still only partially understood. To investigate the trafficking of AMPA receptors in real-time we previously tagged the GluA2 subunit of AMPA receptors with ecliptic pHluorin and studied the effects of NMDA receptor activation. In the present study we have compared the effect of NMDA receptor and group I mGluR activation, using GluA2 tagged with super ecliptic pHluorin (SEP-GluA2 expressed in cultured hippocampal neurons. Surprisingly, agonists of the two receptors, which are both able to induce chemical forms of LTD, had clearly distinct effects on AMPA receptor trafficking. In agreement with our previous work we found that transient NMDA receptor activation results in an initial decrease in surface GluA2 from extrasynaptic sites followed by a delayed reduction in GluA2 from puncta (putative synapses. In contrast, transient activation of group I mGluRs, using DHPG, led to a pronounced but more delayed decrease in GluA2 from the dendritic shafts. Surprisingly, there was no average change in the fluorescence of the puncta. Examination of fluorescence at individual puncta, however, indicated that alterations did take place, with some puncta showing an increase and others a decrease in fluorescence. The effects of DHPG were, like DHPG-induced LTD, prevented by treatment with a protein tyrosine phosphatase (PTP inhibitor. The electrophysiological correlate of the effects of DHPG in the SEP-GluA2 infected cultures was a reduction in mEPSC frequency with no change in amplitude. The implications of these findings for the initial mechanisms of expression of both NMDA receptor- and mGluR-induced LTD are discussed.

  6. Transcriptional peroxisome proliferator-activated receptor γ ...

    African Journals Online (AJOL)

    user

    regulates slow fiber type formation during the transformation of muscle fiber type in S. prenanti. Key words: PGC-1ɑ, ... a master regulator of energy metabolism. PGC-1ɑ is identified ..... which is involved in hormone receptor families, such as ...

  7. Activation of dopamine D3 receptors inhibits reward-related learning induced by cocaine.

    Science.gov (United States)

    Kong, H; Kuang, W; Li, S; Xu, M

    2011-03-10

    Memories of learned associations between the rewarding properties of drugs and environmental cues contribute to craving and relapse in humans. The mesocorticolimbic dopamine (DA) system is involved in reward-related learning induced by drugs of abuse. DA D3 receptors are preferentially expressed in mesocorticolimbic DA projection areas. Genetic and pharmacological studies have shown that DA D3 receptors suppress locomotor-stimulant effects of cocaine and reinstatement of cocaine-seeking behaviors. Activation of the extracellular signal-regulated kinase (ERK) induced by acute cocaine administration is also inhibited by D3 receptors. How D3 receptors modulate cocaine-induced reward-related learning and associated changes in cell signaling in reward circuits in the brain, however, have not been fully investigated. In the present study, we show that D3 receptor mutant mice exhibit potentiated acquisition of conditioned place preference (CPP) at low doses of cocaine compared to wild-type mice. Activation of ERK and CaMKIIα, but not the c-Jun N-terminal kinase and p38, in the nucleus accumbens, amygdala and prefrontal cortex is also potentiated in D3 receptor mutant mice compared to that in wild-type mice following CPP expression. These results support a model in which D3 receptors modulate reward-related learning induced by low doses of cocaine by inhibiting activation of ERK and CaMKIIα in reward circuits in the brain. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Tonically Active α5GABAA Receptors Reduce Motoneuron Excitability and Decrease the Monosynaptic Reflex

    Directory of Open Access Journals (Sweden)

    Martha Canto-Bustos

    2017-09-01

    Full Text Available Motoneurons, the final common path of the Central Nervous System (CNS, are under a complex control of its excitability in order to precisely translate the interneuronal pattern of activity into skeletal muscle contraction and relaxation. To fulfill this relevant function, motoneurons are provided with a vast repertoire of receptors and channels, including the extrasynaptic GABAA receptors which have been poorly investigated. Here, we confirmed that extrasynaptic α5 subunit-containing GABAA receptors localize with choline acetyltransferase (ChAT positive cells, suggesting that these receptors are expressed in turtle motoneurons as previously reported in rodents. In these cells, α5GABAA receptors are activated by ambient GABA, producing a tonic shunt that reduces motoneurons’ membrane resistance and affects their action potential firing properties. In addition, α5GABAA receptors shunted the synaptic excitatory inputs depressing the monosynaptic reflex (MSR induced by activation of primary afferents. Therefore, our results suggest that α5GABAA receptors may play a relevant physiological role in motor control.

  9. Helix 11 Dynamics is Critical for Constitutive Androstane Receptor Activity

    OpenAIRE

    Wright, Edward; Busby, Scott A.; Wisecarver, Sarah; Vincent, Jeremy; Griffin, Patrick R.; Fernandez, Elias J.

    2011-01-01

    The constitutive androstane receptor (CAR) transactivation can occur in the absence of exogenous ligand and this activity is enhanced by agonists TCPOBOP and meclizine. We use biophysical and cell-based assays to show that increased activity of CAR(TCPOBOP) relative to CAR(meclizine) corresponds to a higher affinity of CAR(TCPOBOP) for the steroid receptor coactivator-1. Additionally, steady-state fluorescence spectra suggest conformational differences between CAR(TCPOBOP):RXR and CAR(meclizi...

  10. Mincle suppresses Toll-like receptor 4 activation.

    Science.gov (United States)

    Greco, Stephanie H; Mahmood, Syed Kashif; Vahle, Anne-Kristin; Ochi, Atsuo; Batel, Jennifer; Deutsch, Michael; Barilla, Rocky; Seifert, Lena; Pachter, H Leon; Daley, Donnele; Torres-Hernandez, Alejandro; Hundeyin, Mautin; Mani, Vishnu R; Miller, George

    2016-07-01

    Regulation of Toll-like receptor responses is critical for limiting tissue injury and autoimmunity in both sepsis and sterile inflammation. We found that Mincle, a C-type lectin receptor, regulates proinflammatory Toll-like receptor 4 signaling. Specifically, Mincle ligation diminishes Toll-like receptor 4-mediated inflammation, whereas Mincle deletion or knockdown results in marked hyperresponsiveness to lipopolysaccharide in vitro, as well as overwhelming lipopolysaccharide-mediated inflammation in vivo. Mechanistically, Mincle deletion does not up-regulate Toll-like receptor 4 expression or reduce interleukin 10 production after Toll-like receptor 4 ligation; however, Mincle deletion decreases production of the p38 mitogen-activated protein kinase-dependent inhibitory intermediate suppressor of cytokine signaling 1, A20, and ABIN3 and increases expression of the Toll-like receptor 4 coreceptor CD14. Blockade of CD14 mitigates the increased sensitivity of Mincle(-/-) leukocytes to Toll-like receptor 4 ligation. Collectively, we describe a major role for Mincle in suppressing Toll-like receptor 4 responses and implicate its importance in nonmycobacterial models of inflammation. © Society for Leukocyte Biology.

  11. Differential actions of antiparkinson agents at multiple classes of monoaminergic receptor. III. Agonist and antagonist properties at serotonin, 5-HT(1) and 5-HT(2), receptor subtypes.

    Science.gov (United States)

    Newman-Tancredi, Adrian; Cussac, Didier; Quentric, Yann; Touzard, Manuelle; Verrièle, Laurence; Carpentier, Nathalie; Millan, Mark J

    2002-11-01

    Although certain antiparkinson agents interact with serotonin (5-HT) receptors, little information is available concerning functional actions. Herein, we characterized efficacies of apomorphine, bromocriptine, cabergoline, lisuride, piribedil, pergolide, roxindole, and terguride at human (h)5-HT(1A), h5-HT(1B), and h5-HT(1D) receptors [guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding], and at h5-HT(2A), h5-HT(2B), and h5-HT(2C) receptors (depletion of membrane-bound [(3)H]phosphatydilinositol). All drugs stimulated h5-HT(1A) receptors with efficacies (compared with 5-HT, 100%) ranging from modest (apomorphine, 35%) to high (cabergoline, 93%). At h5-HT(1B) receptors, efficacies varied from mild (terguride, 37%) to marked (cabergoline, 102%) and potencies were modest (pEC(50) values of 5.8-7.6): h5-HT(1D) sites were activated with a similar range of efficacies and greater potency (7.1-8.5). Piribedil and apomorphine were inactive at h5-HT(1B) and h5-HT(1D) receptors. At h5-HT(2A) receptors, terguride, lisuride, bromocriptine, cabergoline, and pergolide displayed potent (7.6-8.8) agonist properties (49-103%), whereas apomorphine and roxindole were antagonists and piribedil was inactive. Only pergolide (113%/8.2) and cabergoline (123%/8.6) displayed pronounced agonist properties at h5-HT(2B) receptors. At 5-HT(2C) receptors, lisuride, bromocriptine, pergolide, and cabergoline were efficacious (75-96%) agonists, apomorphine and terguride were antagonists, and piribedil was inactive. MDL100,907 and SB242,084, selective antagonists at 5-HT(2A) and 5-HT(2C) receptors, respectively, abolished these actions of pergolide, cabergoline, and bromocriptine. In conclusion, antiparkinson agents display markedly different patterns of agonist and antagonist properties at multiple 5-HT receptor subtypes. Although all show modest (agonist) activity at 5-HT(1A) sites, their contrasting actions at 5-HT(2A) and 5-HT(2C) sites may be of particular significance to their

  12. Functional properties of Virus-Encoded and Virus-Regulated 7TM Receptors

    DEFF Research Database (Denmark)

    Spiess, Katja; Rosenkilde, Mette Marie

    2014-01-01

    During co-evolution with their hosts, viruses have developed several survival strategies that involve exploitation of 7TM receptors. These include virus-encoded 7TM receptors and ligands and viral regulation of endogenous receptors. Many functional properties have been ascribed to virus-exploited...

  13. Nuclear receptor corepressor-dependent repression of peroxisome-proliferator-activated receptor delta-mediated transactivation

    DEFF Research Database (Denmark)

    Krogsdam, Anne-M; Nielsen, Curt A F; Neve, Søren

    2002-01-01

    delta-RXR alpha heterodimer bound to an acyl-CoA oxidase (ACO)-type peroxisome-proliferator response element recruited a glutathione S-transferase-NCoR fusion protein in a ligand-independent manner. Contrasting with most other nuclear receptors, PPAR delta was found to interact equally well......The nuclear receptor corepressor (NCoR) was isolated as a peroxisome-proliferator-activated receptor (PPAR) delta interacting protein using the yeast two-hybrid system. NCoR interacted strongly with the ligand-binding domain of PPAR delta, whereas interactions with the ligand-binding domains...

  14. Conformation guides molecular efficacy in docking screens of activated β-2 adrenergic G protein coupled receptor.

    Science.gov (United States)

    Weiss, Dahlia R; Ahn, SeungKirl; Sassano, Maria F; Kleist, Andrew; Zhu, Xiao; Strachan, Ryan; Roth, Bryan L; Lefkowitz, Robert J; Shoichet, Brian K

    2013-05-17

    A prospective, large library virtual screen against an activated β2-adrenergic receptor (β2AR) structure returned potent agonists to the exclusion of inverse-agonists, providing the first complement to the previous virtual screening campaigns against inverse-agonist-bound G protein coupled receptor (GPCR) structures, which predicted only inverse-agonists. In addition, two hits recapitulated the signaling profile of the co-crystal ligand with respect to the G protein and arrestin mediated signaling. This functional fidelity has important implications in drug design, as the ability to predict ligands with predefined signaling properties is highly desirable. However, the agonist-bound state provides an uncertain template for modeling the activated conformation of other GPCRs, as a dopamine D2 receptor (DRD2) activated model templated on the activated β2AR structure returned few hits of only marginal potency.

  15. Inhibitors for Androgen Receptor Activation Surfaces

    Science.gov (United States)

    2007-09-01

    times and the electron-rich iodine groups of Triac representing particularly good markers. Control soaks with solvent ( DMSO ) reveal no similar...electron-rich iodine groups of Triac represent particu- larly good markers. Control soaks with solvent ( DMSO ) reveal no similar effects on coregulator...3-(dibutylamino)-1-(4-hexylphenyl)propan-1-one DMSO , dimethylsulfoxide DTT, dithiothreitol ER, estrogen receptor GST, glutathione S-transferase

  16. Modulation of β-catenin signaling by glucagon receptor activation.

    Directory of Open Access Journals (Sweden)

    Jiyuan Ke

    Full Text Available The glucagon receptor (GCGR is a member of the class B G protein-coupled receptor family. Activation of GCGR by glucagon leads to increased glucose production by the liver. Thus, glucagon is a key component of glucose homeostasis by counteracting the effect of insulin. In this report, we found that in addition to activation of the classic cAMP/protein kinase A (PKA pathway, activation of GCGR also induced β-catenin stabilization and activated β-catenin-mediated transcription. Activation of β-catenin signaling was PKA-dependent, consistent with previous reports on the parathyroid hormone receptor type 1 (PTH1R and glucagon-like peptide 1 (GLP-1R receptors. Since low-density-lipoprotein receptor-related protein 5 (Lrp5 is an essential co-receptor required for Wnt protein mediated β-catenin signaling, we examined the role of Lrp5 in glucagon-induced β-catenin signaling. Cotransfection with Lrp5 enhanced the glucagon-induced β-catenin stabilization and TCF promoter-mediated transcription. Inhibiting Lrp5/6 function using Dickkopf-1(DKK1 or by expression of the Lrp5 extracellular domain blocked glucagon-induced β-catenin signaling. Furthermore, we showed that Lrp5 physically interacted with GCGR by immunoprecipitation and bioluminescence resonance energy transfer assays. Together, these results reveal an unexpected crosstalk between glucagon and β-catenin signaling, and may help to explain the metabolic phenotypes of Lrp5/6 mutations.

  17. CINPA1 Is an Inhibitor of Constitutive Androstane Receptor That Does Not Activate Pregnane X Receptor

    OpenAIRE

    Cherian, Milu T; Lin, Wenwei; Wu, Jing; Chen, Taosheng

    2015-01-01

    Constitutive androstane receptor (CAR) and pregnane X receptor (PXR) are xenobiotic sensors that enhance the detoxification and elimination of xenobiotics and endobiotics by modulating the expression of genes encoding drug-metabolizing enzymes and transporters. Elevated levels of drug-metabolizing enzymes and efflux transporters, resulting from CAR activation in various cancers, promote the elimination of chemotherapeutic agents, leading to reduced therapeutic effectiveness and acquired drug ...

  18. Embelin and its derivatives unravel the signaling, proinflammatory and antiatherogenic properties of GPR84 receptor.

    Science.gov (United States)

    Gaidarov, Ibragim; Anthony, Todd; Gatlin, Joel; Chen, Xiaohua; Mills, David; Solomon, Michelle; Han, Sangdon; Semple, Graeme; Unett, David J

    2018-05-01

    GPR84 is an orphan G-protein coupled receptor, expressed on monocytes, macrophages and neutrophils and is significantly upregulated by inflammatory stimuli. The physiological role of GPR84 remains largely unknown. Medium chain fatty acids (MCFA) activate the receptor and have been proposed to be its endogenous ligands, although the high concentrations of MCFAs required for receptor activation generally exceed normal physiological levels. We identified the natural product embelin as a highly potent and selective surrogate GPR84 agonist (originally disclosed in patent application WO2007027661A2, 2007) and synthesized close structural analogs with widely varying receptor activities. These tools were used to perform a comprehensive study of GPR84 signaling and function in recombinant cells and in primary human macrophages and neutrophils. Activation of recombinant GPR84 by embelin in HEK293 cells results in G i/o as well as G12/13-Rho signaling. In human macrophages, GPR84 initiates PTX sensitive Erk1/2 and Akt phosphorylation, PI-3 kinase activation, calcium flux, and release of prostaglandin E2. In addition, GPR84 signaling in macrophages elicits G i Gβγ-mediated augmentation of intracellular cAMP, rather than the decrease expected from G iα engagement. GPR84 activation drives human neutrophil chemotaxis and primes them for amplification of oxidative burst induced by FMLP and C5A. Loss of GPR84 is associated with attenuated LPS-induced release of proinflammatory mediators IL-6, KC-GROα, VEGF, MIP-2 and NGAL from peritoneal exudates. While initiating numerous proinflammatory activities in macrophages and neutrophils, GPR84 also possesses GPR109A-like antiatherosclerotic properties in macrophages. Macrophage receptor activation leads to upregulation of cholesterol transporters ABCA1 and ABCG1 and stimulates reverse cholesterol transport. These data suggest that GPR84 may be a target of therapeutic value and that distinct modes of receptor modulation (inhibition vs

  19. Dynamic regulation of Drosophila nuclear receptor activity in vivo.

    Science.gov (United States)

    Palanker, Laura; Necakov, Aleksandar S; Sampson, Heidi M; Ni, Ruoyu; Hu, Chun; Thummel, Carl S; Krause, Henry M

    2006-09-01

    Nuclear receptors are a large family of transcription factors that play major roles in development, metamorphosis, metabolism and disease. To determine how, where and when nuclear receptors are regulated by small chemical ligands and/or protein partners, we have used a 'ligand sensor' system to visualize spatial activity patterns for each of the 18 Drosophila nuclear receptors in live developing animals. Transgenic lines were established that express the ligand binding domain of each nuclear receptor fused to the DNA-binding domain of yeast GAL4. When combined with a GAL4-responsive reporter gene, the fusion proteins show tissue- and stage-specific patterns of activation. We show that these responses accurately reflect the presence of endogenous and exogenously added hormone, and that they can be modulated by nuclear receptor partner proteins. The amnioserosa, yolk, midgut and fat body, which play major roles in lipid storage, metabolism and developmental timing, were identified as frequent sites of nuclear receptor activity. We also see dynamic changes in activation that are indicative of sweeping changes in ligand and/or co-factor production. The screening of a small compound library using this system identified the angular psoralen angelicin and the insect growth regulator fenoxycarb as activators of the Ultraspiracle (USP) ligand-binding domain. These results demonstrate the utility of this system for the functional dissection of nuclear receptor pathways and for the development of new receptor agonists and antagonists that can be used to modulate metabolism and disease and to develop more effective means of insect control.

  20. Endogenous fatty acid ethanolamides suppress nicotine-induced activation of mesolimbic dopamine neurons through nuclear receptors.

    Science.gov (United States)

    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.

  1. Activation of Adenylyl Cyclase Causes Stimulation of Adenosine Receptors

    Directory of Open Access Journals (Sweden)

    Thomas Pleli

    2018-03-01

    Full Text Available Background/Aims: Signaling of Gs protein-coupled receptors (GsPCRs is accomplished by stimulation of adenylyl cyclase, causing an increase of the intracellular cAMP concentration, activation of the intracellular cAMP effectors protein kinase A (PKA and Epac, and an efflux of cAMP, the function of which is still unclear. Methods: Activation of adenylyl cyclase by GsPCR agonists or cholera toxin was monitored by measurement of the intracellular cAMP concentration by ELISA, anti-phospho-PKA substrate motif phosphorylation by immunoblotting, and an Epac-FRET assay in the presence and absence of adenosine receptor antagonists or ecto-nucleotide phosphodiesterase/pyrophosphatase2 (eNPP2 inhibitors. The production of AMP from cAMP by recombinant eNPP2 was measured by HPLC. Extracellular adenosine was determined by LC-MS/MS, extracellular ATP by luciferase and LC-MS/MS. The expression of eNPP isoenzymes 1-3 was examined by RT-PCR. The expression of multidrug resistance protein 4 was suppressed by siRNA. Results: Here we show that the activation of GsPCRs and the GsPCRs-independent activation of Gs proteins and adenylyl cyclase by cholera toxin induce stimulation of cell surface adenosine receptors (A2A or A2B adenosine receptors. In PC12 cells stimulation of adenylyl cyclase by GsPCR or cholera toxin caused activation of A2A adenosine receptors by an autocrine signaling pathway involving cAMP efflux through multidrug resistance protein 4 and hydrolysis of released cAMP to AMP by eNPP2. In contrast, in PC3 cells cholera toxin- and GsPCR-induced stimulation of adenylyl cyclase resulted in the activation of A2B adenosine receptors. Conclusion: Our findings show that stimulation of adenylyl cyclase causes a remarkable activation of cell surface adenosine receptors.

  2. Flavonoids with M1 Muscarinic Acetylcholine Receptor Binding Activity

    Directory of Open Access Journals (Sweden)

    Meyyammai Swaminathan

    2014-06-01

    Full Text Available Muscarinic acetylcholine receptor-active compounds have potential for the treatment of Alzheimer’s disease. In this study, a series of natural and synthetic flavones and flavonols was assayed in vitro for their ability to inhibit radioligand binding at human cloned M1 muscarinic receptors. Several compounds were found to possess competitive binding affinity (Ki = 40–110 µM, comparable to that of acetylcholine (Ki = 59 µM. Despite the fact that these compounds lack a positively-charged ammonium group under physiological conditions, molecular modelling studies suggested that they bind to the orthosteric site of the receptor, mainly through non-polar interactions.

  3. Assembly and activation of neurotrophic factor receptor complexes.

    Science.gov (United States)

    Simi, Anastasia; Ibáñez, Carlos F

    2010-04-01

    Neurotrophic factors play important roles in the development and function of both neuronal and glial elements of the central and peripheral nervous systems. Their functional diversity is in part based on their ability to interact with alternative complexes of receptor molecules. This review focuses on our current understanding of the mechanisms that govern the assembly and activation of neurotrophic factor receptor complexes. The realization that many, if not the majority, of these complexes exist in a preassembled form at the plasma membrane has forced the revision of classical ligand-mediated oligomerization models, and led to the discovery of novel mechanisms of receptor activation and generation of signaling diversity which are likely to be shared by many different classes of receptors.

  4. Quantum chemical study of agonist-receptor vibrational interactions for activation of the glutamate receptor.

    Science.gov (United States)

    Kubo, M; Odai, K; Sugimoto, T; Ito, E

    2001-06-01

    To understand the mechanism of activation of a receptor by its agonist, the excitation and relaxation processes of the vibrational states of the receptor should be examined. As a first approach to this problem, we calculated the normal vibrational modes of agonists (glutamate and kainate) and an antagonist (6-cyano-7-nitroquinoxaline-2,3-dione: CNQX) of the glutamate receptor, and then investigated the vibrational interactions between kainate and the binding site of glutamate receptor subunit GluR2 by use of a semiempirical molecular orbital method (MOPAC2000-PM3). We found that two local vibrational modes of kainate, which were also observed in glutamate but not in CNQX, interacted through hydrogen bonds with the vibrational modes of GluR2: (i) the bending vibration of the amine group of kainate, interacting with the stretching vibration of the carboxyl group of Glu705 of GluR2, and (ii) the symmetric stretching vibration of the carboxyl group of kainate, interacting with the bending vibration of the guanidinium group of Arg485. We also found collective modes with low frequency at the binding site of GluR2 in the kainate-bound state. The vibrational energy supplied by an agonist may flow from the high-frequency local modes to the low-frequency collective modes in a receptor, resulting in receptor activation.

  5. Peroxisome Proliferator-Activated Receptor and Vitamin D Receptor Signaling Pathways in Cancer Cells

    Directory of Open Access Journals (Sweden)

    Yasuko Kitagishi

    2013-10-01

    Full Text Available Peroxisome proliferator-activated receptors (PPARs are members of the superfamily of nuclear hormone receptors, which respond to specific ligands such as polyunsaturated fatty acids by altering gene expression. Three subtypes of this receptor have been discovered, each evolving to achieve different biological functions. Like other nuclear receptors, the transcriptional activity of PPARs is affected not only by ligand-stimulation, but also by cross-talk with other molecules. For example, both PPARs and the RXRs are ligand-activated transcription factors that coordinately regulate gene expression. In addition, PPARs and vitamin D receptor (VDR signaling pathways regulate a multitude of genes that are of importance for cellular functions including cell proliferation and cell differentiation. Interaction of the PPARs and VDR signaling pathways has been shown at the level of molecular cross-regulation of their transcription factor. A variety of ligands influencing the PPARs and VDR signaling pathways have been shown to reveal chemopreventive potential by mediating tumor suppressive activities in human cancers. Use of these compounds may represent a potential novel strategy to prevent cancers. This review summarizes the roles of the PPARs and the VDR in pathogenesis and progression of cancer.

  6. Peroxisome Proliferator-Activated Receptor and Vitamin D Receptor Signaling Pathways in Cancer Cells

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Satoru, E-mail: smatsuda@cc.nara-wu.ac.jp; Kitagishi, Yasuko [Department of Food Science and Nutrition, Nara Women’s University, Kita-Uoya Nishimachi, Nara 630-8506 (Japan)

    2013-10-21

    Peroxisome proliferator-activated receptors (PPARs) are members of the superfamily of nuclear hormone receptors, which respond to specific ligands such as polyunsaturated fatty acids by altering gene expression. Three subtypes of this receptor have been discovered, each evolving to achieve different biological functions. Like other nuclear receptors, the transcriptional activity of PPARs is affected not only by ligand-stimulation, but also by cross-talk with other molecules. For example, both PPARs and the RXRs are ligand-activated transcription factors that coordinately regulate gene expression. In addition, PPARs and vitamin D receptor (VDR) signaling pathways regulate a multitude of genes that are of importance for cellular functions including cell proliferation and cell differentiation. Interaction of the PPARs and VDR signaling pathways has been shown at the level of molecular cross-regulation of their transcription factor. A variety of ligands influencing the PPARs and VDR signaling pathways have been shown to reveal chemopreventive potential by mediating tumor suppressive activities in human cancers. Use of these compounds may represent a potential novel strategy to prevent cancers. This review summarizes the roles of the PPARs and the VDR in pathogenesis and progression of cancer.

  7. Peroxisome Proliferator-Activated Receptor and Vitamin D Receptor Signaling Pathways in Cancer Cells

    International Nuclear Information System (INIS)

    Matsuda, Satoru; Kitagishi, Yasuko

    2013-01-01

    Peroxisome proliferator-activated receptors (PPARs) are members of the superfamily of nuclear hormone receptors, which respond to specific ligands such as polyunsaturated fatty acids by altering gene expression. Three subtypes of this receptor have been discovered, each evolving to achieve different biological functions. Like other nuclear receptors, the transcriptional activity of PPARs is affected not only by ligand-stimulation, but also by cross-talk with other molecules. For example, both PPARs and the RXRs are ligand-activated transcription factors that coordinately regulate gene expression. In addition, PPARs and vitamin D receptor (VDR) signaling pathways regulate a multitude of genes that are of importance for cellular functions including cell proliferation and cell differentiation. Interaction of the PPARs and VDR signaling pathways has been shown at the level of molecular cross-regulation of their transcription factor. A variety of ligands influencing the PPARs and VDR signaling pathways have been shown to reveal chemopreventive potential by mediating tumor suppressive activities in human cancers. Use of these compounds may represent a potential novel strategy to prevent cancers. This review summarizes the roles of the PPARs and the VDR in pathogenesis and progression of cancer

  8. Neurotrophin receptors expression and JNK pathway activation in human astrocytomas

    International Nuclear Information System (INIS)

    Assimakopoulou, Martha; Kondyli, Maria; Gatzounis, George; Maraziotis, Theodore; Varakis, John

    2007-01-01

    Neurotrophins are growth factors that regulate cell growth, differentiation and apoptosis in the nervous system. Their diverse actions are mediated through two different transmembrane – receptor signaling systems: Trk receptor tyrosine kinases (TrkA, TrkB, TrkC) and p75 NTR neurotrophin receptor. Trk receptors promote cell survival and differentiation while p75 NTR induces, in most cases, the activity of JNK-p53-Bax apoptosis pathway or suppresses intracellular survival signaling cascades. Robust Trk activation blocks p75 NTR -induced apoptosis by suppressing the JNK-p53-Bax pathway. The aim of this exploratory study was to investigate the expression levels of neurotrophin receptors, Trks and p75 NTR , and the activation of JNK pathway in human astrocytomas and in adjacent non-neoplastic brain tissue. Formalin-fixed paraffin-embedded serial sections from 33 supratentorial astrocytomas (5 diffuse fibrillary astrocytomas, WHO grade II; 6 anaplastic astrocytomas, WHO grade III; 22 glioblastomas multiforme, WHO grade IV) were immunostained following microwave pretreatment. Polyclonal antibodies against TrkA, TrkB, TrkC and monoclonal antibodies against p75 NTR and phosphorylated forms of JNK (pJNK) and c-Jun (pc-Jun) were used. The labeling index (LI), defined as the percentage of positive (labeled) cells out of the total number of tumor cells counted, was determined. Moderate to strong, granular cytoplasmic immunoreactivity for TrkA, TrkB and TrkC receptors was detected in greater than or equal to 10% of tumor cells in the majority of tumors independently of grade; on the contrary, p75 NTR receptor expression was found in a small percentage of tumor cells (~1%) in some tumors. The endothelium of tumor capillaries showed conspicuous immunoreactivity for TrkB receptor. Trk immunoreactivity seemed to be localized in some neurons and astrocytes in non-neoplastic tissue. Phosphorylated forms of JNK (pJNK) and c-Jun (pc-Jun) were significantly co-expressed in a tumor

  9. Adiponectin receptors form homomers and heteromers exhibiting distinct ligand binding and intracellular signaling properties.

    Science.gov (United States)

    Almabouada, Farid; Diaz-Ruiz, Alberto; Rabanal-Ruiz, Yoana; Peinado, Juan R; Vazquez-Martinez, Rafael; Malagon, Maria M

    2013-02-01

    Adiponectin binds to two widely expressed receptors (AdipoR1 and AdipoR2) that contain seven transmembrane domains but, unlike G-protein coupled receptors, present an extracellular C terminus and a cytosolic N terminus. Recently, AdipoR1 was found to associate in high order complexes. However, it is still unknown whether AdipoR2 may also form homomers or heteromers with AdipoR1 or if such interactions may be functionally relevant. Herein, we have analyzed the oligomerization pattern of AdipoRs by FRET and immunoprecipitation and evaluated both the internalization of AdipoRs in response to various adiponectin isoforms and the effect of adiponectin binding to different AdipoR combinations on AMP-activated protein kinase phosphorylation and peroxisome proliferator-activated receptor α activation. Transfection of HEK293AD cells with AdipoR1 and AdipoR2 showed that both receptors colocalize at both the plasma membrane and the endoplasmic reticulum. Co-transfection with the different AdipoR pairs yielded high FRET efficiencies in non-stimulated cells, which indicates that AdipoR1 and AdipoR2 form homo- and heteromeric complexes under resting conditions. Live FRET imaging suggested that both homo- and heteromeric AdipoR complexes dissociate in response to adiponectin, but heteromers separate faster than homomers. Finally, phosphorylation of AMP-activated protein kinase in response to adiponectin was delayed in cells wherein heteromer formation was favored. In sum, our findings indicate that AdipoR1 and AdipoR2 form homo- and heteromers that present unique interaction behaviors and signaling properties. This raises the possibility that the pleiotropic, tissue-dependent functions of adiponectin depend on the expression levels of AdipoR1 and AdipoR2 and, therefore, on the steady-state proportion of homo- and heteromeric complexes.

  10. Molecular characterization of the receptor binding structure-activity relationships of influenza B virus hemagglutinin.

    Science.gov (United States)

    Carbone, V; Kim, H; Huang, J X; Baker, M A; Ong, C; Cooper, M A; Li, J; Rockman, S; Velkov, T

    2013-01-01

    Selectivity of α2,6-linked human-like receptors by B hemagglutinin (HA) is yet to be fully understood. This study integrates binding data with structure-recognition models to examine the impact of regional-specific sequence variations within the receptor-binding pocket on selectivity and structure activity relationships (SAR). The receptor-binding selectivity of influenza B HAs corresponding to either B/Victoria/2/1987 or the B/Yamagata/16/88 lineages was examined using surface plasmon resonance, solid-phase ELISA and gel-capture assays. Our SAR data showed that the presence of asialyl sugar units is the main determinant of receptor preference of α2,6 versus α2,3 receptor binding. Changes to the type of sialyl-glycan linkage present on receptors exhibit only a minor effect upon binding affinity. Homology-based structural models revealed that structural properties within the HA pocket, such as a glyco-conjugate at Asn194 on the 190-helix, sterically interfere with binding to avian receptor analogs by blocking the exit path of the asialyl sugars. Similarly, naturally occurring substitutions in the C-terminal region of the 190-helix and near the N-terminal end of the 140-loop narrows the horizontal borders of the binding pocket, which restricts access of the avian receptor analog LSTa. This study helps bridge the gap between ligand structure and receptor recognition for influenza B HA; and provides a consensus SAR model for the binding of human and avian receptor analogs to influenza B HA.

  11. Neurotrophin receptors expression and JNK pathway activation in human astrocytomas

    Directory of Open Access Journals (Sweden)

    Maraziotis Theodore

    2007-10-01

    Full Text Available Abstract Background Neurotrophins are growth factors that regulate cell growth, differentiation and apoptosis in the nervous system. Their diverse actions are mediated through two different transmembrane – receptor signaling systems: Trk receptor tyrosine kinases (TrkA, TrkB, TrkC and p75NTR neurotrophin receptor. Trk receptors promote cell survival and differentiation while p75NTR induces, in most cases, the activity of JNK-p53-Bax apoptosis pathway or suppresses intracellular survival signaling cascades. Robust Trk activation blocks p75NTR -induced apoptosis by suppressing the JNK-p53-Bax pathway. The aim of this exploratory study was to investigate the expression levels of neurotrophin receptors, Trks and p75NTR, and the activation of JNK pathway in human astrocytomas and in adjacent non-neoplastic brain tissue. Methods Formalin-fixed paraffin-embedded serial sections from 33 supratentorial astrocytomas (5 diffuse fibrillary astrocytomas, WHO grade II; 6 anaplastic astrocytomas, WHO grade III; 22 glioblastomas multiforme, WHO grade IV were immunostained following microwave pretreatment. Polyclonal antibodies against TrkA, TrkB, TrkC and monoclonal antibodies against p75NTR and phosphorylated forms of JNK (pJNK and c-Jun (pc-Jun were used. The labeling index (LI, defined as the percentage of positive (labeled cells out of the total number of tumor cells counted, was determined. Results Moderate to strong, granular cytoplasmic immunoreactivity for TrkA, TrkB and TrkC receptors was detected in greater than or equal to 10% of tumor cells in the majority of tumors independently of grade; on the contrary, p75NTR receptor expression was found in a small percentage of tumor cells (~1% in some tumors. The endothelium of tumor capillaries showed conspicuous immunoreactivity for TrkB receptor. Trk immunoreactivity seemed to be localized in some neurons and astrocytes in non-neoplastic tissue. Phosphorylated forms of JNK (pJNK and c-Jun (pc-Jun were

  12. Activation-induced proteolysis of cytoplasmic domain of zeta in T cell receptors and Fc receptors.

    Science.gov (United States)

    Taupin, J L; Anderson, P

    1994-12-01

    The CD3-T cell receptor (TCR) complex on T cells and the Fc gamma receptor type III (Fc gamma RIII)-zeta-gamma complex on natural killer cells are functionally analogous activation receptors that associate with a family of disulfide-linked dimers composed of the related subunits zeta and gamma. Immunochemical analysis of receptor complexes separated on two-dimensional diagonal gels allowed the identification of a previously uncharacterized zeta-p14 heterodimer. zeta-p14 is a component of both CD3-TCR and Fc gamma RIII-zeta-gamma. Peptide mapping analysis shows that p14 is structurally related to zeta, suggesting that it is either: (i) derived from zeta proteolytically or (ii) the product of an alternatively spliced mRNA. The observation that COS cells transformed with a cDNA encoding zeta express zeta-p14 supports the former possibility. The expression of CD3-TCR complexes including zeta-p14 increases following activation with phorbol 12-myristate 13-acetate or concanavalin A, suggesting that proteolysis of zeta may contribute to receptor modulation or desensitization.

  13. Functionally biased signalling properties of 7TM receptors - opportunities for drug development for the ghrelin receptor

    DEFF Research Database (Denmark)

    Sivertsen, B; Holliday, N; Madsen, A N

    2013-01-01

    UNLABELLED: The ghrelin receptor is a 7 transmembrane (7TM) receptor involved in a variety of physiological functions including growth hormone secretion, increased food intake and fat accumulation as well as modulation of reward and cognitive functions. Because of its important role in metabolism...... and energy expenditure, the ghrelin receptor has become an important therapeutic target for drug design and the development of anti-obesity compounds. However, none of the compounds developed so far have been approved for commercial use. Interestingly, the ghrelin receptor is able to signal through several...... review, we have described how ligands and mutations in the 7TM receptor may bias the receptors to favour either one G-protein over another or to promote G-protein independent signalling pathways rather than G-protein-dependent pathways. For the ghrelin receptor, both agonist and inverse agonists have...

  14. ANGIOTENSIN RECEPTOR BLOCKERS WITH PLEIOTROPIC PROPERTIES: A NEW STANDARD IN CARDIOVASCULAR RISK MANAGEMENT AND TREATMENT OF HYPERTENSION

    Directory of Open Access Journals (Sweden)

    V. I. Podzolkov

    2017-01-01

    Full Text Available An increase in the activity of the renin-angiotensin-aldosterone system is one of the most important mechanisms for the realization of the cardiovascular continuum. The role that angiotensin receptor blockers play in achieving target figures of blood pressure and reducing cardiovascular risk is discussed. The importance of pleiotropic properties of angiotensin receptor blockers (in particular, activation of peroxisome proliferator-activated receptors gamma – PPAR-γ in the management of patients with insulin resistance, obesity, dyslipidemia is also covered. The evidence base for the use of telmisartan as a drug with pleiotropic effect in patients with arterial hypertension and associated diseases (diabetes mellitus, obesity, renal dysfunction is discussed. 

  15. GABAB-receptor activation alters the firing pattern of dopamine neurons in the rat substantia nigra.

    Science.gov (United States)

    Engberg, G; Kling-Petersen, T; Nissbrandt, H

    1993-11-01

    Previous electrophysiological experiments have emphasized the importance of the firing pattern for the functioning of midbrain dopamine (DA) neurons. In this regard, excitatory amino acid receptors appear to constitute an important modulatory control mechanism. In the present study, extracellular recording techniques were used to investigate the significance of GABAB-receptor activation for the firing properties of DA neurons in the substantia nigra (SN) in the rat. Intravenous administration of the GABAB-receptor agonist baclofen (1-16 mg/kg) was associated with a dose-dependent regularization of the firing pattern, concomitant with a reduction in burst firing. At higher doses (16-32 mg/kg), the firing rate of the DA neurons was dose-dependently decreased. Also, microiontophoretic application of baclofen regularized the firing pattern of nigral DA neurons, including a reduction of burst firing. Both the regularization of the firing pattern and inhibition of firing rate produced by systemic baclofen administration was antagonized by the GABAB-receptor antagonist CGP 35348 (200 mg/kg, i.v.). The GABAA-receptor agonist muscimol produced effects on the firing properties of DA neurons that were opposite to those observed following baclofen, i.e., an increase in firing rate accompanied by a decreased regularity. The NMDA receptor antagonist MK 801 (0.4-3.2 mg/kg, i.v.) produced a moderate, dose-dependent increase in the firing rate of the nigral DA neurons as well as a slightly regularized firing pattern. Pretreatment with MK 801 (3.2 mg/kg, i.v., 3-10 min) did neither promote nor prevent the regularization of the firing pattern or inhibition of firing rate on the nigral DA neurons produced by baclofen. The present results clearly show that GABAB-receptors can alter the firing pattern of nigral DA neurons, hereby counterbalancing the previously described ability of glutamate to induce burst firing activity on these neurons.

  16. Peroxisome proliferator-activated receptor delta activation leads to increased transintestinal cholesterol efflux

    NARCIS (Netherlands)

    Vrins, Carlos L. J.; van der Velde, Astrid E.; van den Oever, Karin; Levels, Johannes H. M.; Huet, Stephane; Elferink, Ronald P. J. Oude; Kuipers, Folkert; Groen, Albert K.

    2009-01-01

    Peroxisome proliferator-activated receptor delta (PPAR delta) is involved in regulation of energy homeostasis. Activation of PPAR delta markedly increases fecal neutral sterol secretion, the last step in reverse cholesterol transport. This phenomenon can neither be explained by increased

  17. Peroxisome proliferator-activated receptor delta activation leads to increased transintestinal cholesterol efflux

    NARCIS (Netherlands)

    Vrins, Carlos L. J.; van der Velde, Astrid E.; van den Oever, Karin; Levels, Johannes H. M.; Huet, Stephane; Oude Elferink, Ronald P. J.; Kuipers, Folkert; Groen, Albert K.

    2009-01-01

    Peroxisome proliferator-activated receptor delta (PPARdelta) is involved in regulation of energy homeostasis. Activation of PPARdelta markedly increases fecal neutral sterol secretion, the last step in reverse cholesterol transport. This phenomenon can neither be explained by increased hepatobiliary

  18. Regulation of Liver Energy Balance by the Nuclear Receptors Farnesoid X Receptor and Peroxisome Proliferator Activated Receptor α.

    Science.gov (United States)

    Kim, Kang Ho; Moore, David D

    2017-01-01

    The liver undergoes major changes in substrate utilization and metabolic output over the daily feeding and fasting cycle. These changes occur acutely in response to hormones such as insulin and glucagon, with rapid changes in signaling pathways mediated by protein phosphorylation and other post-translational modifications. They are also reflected in chronic alterations in gene expression in response to nutrient-sensitive transcription factors. Among these, the nuclear receptors farnesoid X receptor (FXR) and peroxisome proliferator activated receptor α (PPARα) provide an intriguing, coordinated response to maintain energy balance in the liver. FXR is activated in the fed state by bile acids returning to the liver, while PPARα is activated in the fasted state in response to the free fatty acids produced by adipocyte lipolysis or possibly other signals. Key Messages: Previous studies indicate that FXR and PPARα have opposing effects on each other's primary targets in key metabolic pathways including gluconeogenesis. Our more recent work shows that these 2 nuclear receptors coordinately regulate autophagy: FXR suppresses this pathway of nutrient and energy recovery, while PPARα activates it. Another recent study indicates that FXR activates the complement and coagulation pathway, while earlier studies identify this as a negative target of PPARα. Since secretion is a very energy- and nutrient-intensive process for hepatocytes, it is possible that FXR licenses it in the nutrient-rich fed state, while PPARα represses it to spare resources in the fasted state. Energy balance is a potential connection linking FXR and PPARα regulation of autophagy and secretion, 2 seemingly unrelated aspects of hepatocyte function. FXR and PPARα act coordinately to promote energy balance and homeostasis in the liver by regulating autophagy and potentially protein secretion. It is quite likely that their impact extends to additional pathways relevant to hepatic energy balance, and

  19. Human pregnane X receptor is activated by dibenzazepine carbamate-based inhibitors of constitutive androstane receptor.

    Science.gov (United States)

    Jeske, Judith; Windshügel, Björn; Thasler, Wolfgang E; Schwab, Matthias; Burk, Oliver

    2017-06-01

    Unintentional activation of xenosensing nuclear receptors pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR) by clinical drug use is known to produce severe side effects in patients, which may be overcome by co-administering antagonists. However, especially antagonizing CAR is hampered by the lack of specific inhibitors, which do not activate PXR. Recently, compounds based on a dibenzazepine carbamate scaffold were identified as potent CAR inhibitors. However, their potential to activate PXR was not thoroughly investigated, even if the lead compound was named "CAR inhibitor not PXR activator 1" (CINPA1). Thus, we performed a comprehensive analysis of the interaction of CINPA1 and four analogs with PXR. Cellular assays were used to investigate intra- and intermolecular interactions and transactivation activity of PXR as a function of the compounds. Modulation of PXR target gene expression was analyzed in primary human hepatocytes. Ligand binding to PXR was investigated by molecular docking and limited proteolytic digestion. We show here that CINPA1 induced the assembly of the PXR ligand-binding domain, released co-repressors from and recruited co-activators to the receptor. CINPA1 and its analogs induced the PXR-dependent activation of a CYP3A4 reporter gene and CINPA1 induced the expression of endogenous cytochrome P450 genes in primary hepatocytes, while not consistently inhibiting CAR-mediated induction. Molecular docking revealed favorable binding of CINPA1 and analogs to the PXR ligand-binding pocket, which was confirmed in vitro. Altogether, our data provide consistent evidence that compounds with a dibenzazepine carbamate scaffold, such as CINPA1 and its four analogs, bind to and activate PXR.

  20. Modulating Estrogen Receptor-related ReceptorActivity Inhibits Cell Proliferation*

    Science.gov (United States)

    Bianco, Stéphanie; Lanvin, Olivia; Tribollet, Violaine; Macari, Claire; North, Sophie; Vanacker, Jean-Marc

    2009-01-01

    High expression of the estrogen receptor-related receptor (ERR)-α in human tumors is correlated to a poor prognosis, suggesting an involvement of the receptor in cell proliferation. In this study, we show that a synthetic compound (XCT790) that modulates the activity of ERRα reduces the proliferation of various cell lines and blocks the G1/S transition of the cell cycle in an ERRα-dependent manner. XCT790 induces, in a p53-independent manner, the expression of the cell cycle inhibitor p21waf/cip1 at the protein, mRNA, and promoter level, leading to an accumulation of hypophosphorylated Rb. Finally, XCT790 reduces cell tumorigenicity in Nude mice. PMID:19546226

  1. The aryl hydrocarbon receptor and glucocorticoid receptor interact to activate human metallothionein 2A

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Shoko, E-mail: satosho@rs.tus.ac.jp [Laboratory of Nutrition, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555 (Japan); Shirakawa, Hitoshi, E-mail: shirakah@m.tohoku.ac.jp [Laboratory of Nutrition, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555 (Japan); Tomita, Shuhei, E-mail: tomita@med.tottori-u.ac.jp [Division of Molecular Pharmacology, Department of Pathophysiological and Therapeutic Science, Yonago 683-8503 (Japan); Tohkin, Masahiro, E-mail: tohkin@phar.nagoya-cu.ac.jp [Department of Medical Safety Science, Graduate School of Pharmaceutical Science, Nagoya City University, Nagoya 267-8603 (Japan); Gonzalez, Frank J., E-mail: gonzalef@mail.nih.gov [Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892 (United States); Komai, Michio, E-mail: mkomai@m.tohoku.ac.jp [Laboratory of Nutrition, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555 (Japan)

    2013-11-15

    Although the aryl hydrocarbon receptor (AHR) and glucocorticoid receptor (GR) play essential roles in mammalian development, stress responses, and other physiological events, crosstalk between these receptors has been the subject of much debate. Metallothioneins are classic glucocorticoid-inducible genes that were reported to increase upon treatment with AHR agonists in rodent tissues and cultured human cells. In this study, the mechanism of human metallothionein 2A (MT2A) gene transcription activation by AHR was investigated. Cotreatment with 3-methylcholanthrene and dexamethasone, agonists of AHR and GR respectively, synergistically increased MT2A mRNA levels in HepG2 cells. MT2A induction was suppressed by RNA interference against AHR or GR. Coimmunoprecipitation experiments revealed a physical interaction between AHR and GR proteins. Moreover, chromatin immunoprecipitation assays indicated that AHR was recruited to the glucocorticoid response element in the MT2A promoter. Thus, we provide a novel mechanism whereby AHR modulates expression of human MT2A via the glucocorticoid response element and protein–protein interactions with GR. - Highlights: • Aryl hydrocarbon receptor forms a complex with glucocorticoid receptor in cells. • Human metallothionein gene is regulated by the AHR and GR interaction. • AHR–GR complex binds to glucocorticoid response element in metallothionein gene. • We demonstrated a novel transcriptional mechanism via AHR and GR interaction.

  2. The aryl hydrocarbon receptor and glucocorticoid receptor interact to activate human metallothionein 2A

    International Nuclear Information System (INIS)

    Sato, Shoko; Shirakawa, Hitoshi; Tomita, Shuhei; Tohkin, Masahiro; Gonzalez, Frank J.; Komai, Michio

    2013-01-01

    Although the aryl hydrocarbon receptor (AHR) and glucocorticoid receptor (GR) play essential roles in mammalian development, stress responses, and other physiological events, crosstalk between these receptors has been the subject of much debate. Metallothioneins are classic glucocorticoid-inducible genes that were reported to increase upon treatment with AHR agonists in rodent tissues and cultured human cells. In this study, the mechanism of human metallothionein 2A (MT2A) gene transcription activation by AHR was investigated. Cotreatment with 3-methylcholanthrene and dexamethasone, agonists of AHR and GR respectively, synergistically increased MT2A mRNA levels in HepG2 cells. MT2A induction was suppressed by RNA interference against AHR or GR. Coimmunoprecipitation experiments revealed a physical interaction between AHR and GR proteins. Moreover, chromatin immunoprecipitation assays indicated that AHR was recruited to the glucocorticoid response element in the MT2A promoter. Thus, we provide a novel mechanism whereby AHR modulates expression of human MT2A via the glucocorticoid response element and protein–protein interactions with GR. - Highlights: • Aryl hydrocarbon receptor forms a complex with glucocorticoid receptor in cells. • Human metallothionein gene is regulated by the AHR and GR interaction. • AHR–GR complex binds to glucocorticoid response element in metallothionein gene. • We demonstrated a novel transcriptional mechanism via AHR and GR interaction

  3. Intramolecular Crosstalk between Catalytic Activities of Receptor Kinases

    KAUST Repository

    Kwezi, Lusisizwe

    2018-01-22

    Signal modulation is important for the growth and development of plants and this process is mediated by a number of factors including physiological growth regulators and their associated signal transduction pathways. Protein kinases play a central role in signaling, including those involving pathogen response mechanisms. We previously demonstrated an active guanylate cyclase (GC) catalytic center in the brassinosteroid insensitive receptor (AtBRI1) within an active intracellular kinase domain resulting in dual enzymatic activity. Here we propose a novel type of receptor architecture that is characterized by a functional GC catalytic center nested in the cytosolic kinase domain enabling intramolecular crosstalk. This may be through a cGMP-AtBRI1 complex forming that may induce a negative feedback mechanism leading to desensitisation of the receptor, regulated through the cGMP production pathway. We further argue that the comparatively low but highly localized cGMP generated by the GC in response to a ligand is sufficient to modulate the kinase activity. This type of receptor therefore provides a molecular switch that directly and/or indirectly affects ligand dependent phosphorylation of downstream signaling cascades and suggests that subsequent signal transduction and modulation works in conjunction with the kinase in downstream signaling.

  4. Intramolecular Crosstalk between Catalytic Activities of Receptor Kinases

    KAUST Repository

    Kwezi, Lusisizwe; Wheeler, Janet I; Marondedze, Claudius; Gehring, Christoph A; Irving, Helen R

    2018-01-01

    Signal modulation is important for the growth and development of plants and this process is mediated by a number of factors including physiological growth regulators and their associated signal transduction pathways. Protein kinases play a central role in signaling, including those involving pathogen response mechanisms. We previously demonstrated an active guanylate cyclase (GC) catalytic center in the brassinosteroid insensitive receptor (AtBRI1) within an active intracellular kinase domain resulting in dual enzymatic activity. Here we propose a novel type of receptor architecture that is characterized by a functional GC catalytic center nested in the cytosolic kinase domain enabling intramolecular crosstalk. This may be through a cGMP-AtBRI1 complex forming that may induce a negative feedback mechanism leading to desensitisation of the receptor, regulated through the cGMP production pathway. We further argue that the comparatively low but highly localized cGMP generated by the GC in response to a ligand is sufficient to modulate the kinase activity. This type of receptor therefore provides a molecular switch that directly and/or indirectly affects ligand dependent phosphorylation of downstream signaling cascades and suggests that subsequent signal transduction and modulation works in conjunction with the kinase in downstream signaling.

  5. How Far Does a Receptor Influence Vibrational Properties of an Odorant?

    DEFF Research Database (Denmark)

    Reese, Anna; List, Nanna Holmgaard; Kongsted, Jacob

    2016-01-01

    -assisted electron transfer. Through molecular dynamics simulations we elucidate the binding specificity of a receptor towards acetophenone odorant. The vibrational properties of acetophenone inside the receptor are then studied by the polarizable embedding density functional theory approach, allowing to quantify...... protein-odorant interactions. Finally, we judge whether the effects of the protein provide any indications towards the existing theories of olfaction....

  6. Structure-activity relationships of strychnine analogues at glycine receptors

    DEFF Research Database (Denmark)

    Mohsen, A.M.Y.; Heller, Eberhard; Holzgrabe, Ulrike

    2014-01-01

    Nine strychnine derivatives including neostrychnine, strychnidine, isostrychnine, 21,22-dihydro-21-hydroxy-22-oxo-strychnine, and several hydrogenated analogs were synthesized, and their antagonistic activities at human α1 and α1β glycine receptors were evaluated. Isostrychnine has shown the best...... pharmacological profile exhibiting an IC50 value of 1.6 μM at α1 glycine receptors and 3.7-fold preference towards the α1 subtype. SAR Analysis indicates that the lactam moiety and the C(21)[DOUBLE BOND]C(22) bond in strychnine are essential structural features for its high antagonistic potency at glycine...

  7. Diabetes and obesity treatment based on dual incretin receptor activation

    DEFF Research Database (Denmark)

    Skow, M A; Bergmann, N C; Knop, F K

    2016-01-01

    , whereas GIP seems to affect lipid metabolism. The introduction of selective GLP-1 receptor (GLP-1R) agonists for the treatment of type 2 diabetes and obesity has increased the scientific and clinical interest in incretins. Combining the body weight-lowering and glucose-lowering effects of GLP-1...... with a more potent improvement of β cell function through additional GIP action could potentially offer a more effective treatment of diabetes and obesity, with fewer adverse effects than selective GLP-1R agonists; therefore, new drugs designed to co-activate both the GIP receptor (GIPR) and the GLP-1R...

  8. Influence of phasic and tonic dopamine release on receptor activation

    DEFF Research Database (Denmark)

    Dreyer, Jakob Kristoffer Kisbye; Herrik, Kjartan F; Berg, Rune W

    2010-01-01

    Tonic and phasic dopamine release is implicated in learning, motivation, and motor functions. However, the relationship between spike patterns in dopaminergic neurons, the extracellular concentration of dopamine, and activation of dopamine receptors remains unresolved. In the present study, we...... develop a computational model of dopamine signaling that give insight into the relationship between the dynamics of release and occupancy of D(1) and D(2) receptors. The model is derived from first principles using experimental data. It has no free parameters and offers unbiased estimation...

  9. Liver X receptor and peroxisome proliferator-activated receptor as integrators of lipid homeostasis and immunity.

    Science.gov (United States)

    Kidani, Yoko; Bensinger, Steven J

    2012-09-01

    Lipid metabolism has emerged as an important modulator of innate and adaptive immune cell fate and function. The lipid-activated transcription factors peroxisome proliferator-activated receptor (PPAR) α, β/δ, γ and liver X receptor (LXR) are members of the nuclear receptor superfamily that have a well-defined role in regulating lipid homeostasis and metabolic diseases. Accumulated evidence over the last decade indicates that PPAR and LXR signaling also influence multiple facets of inflammation and immunity, thereby providing important crosstalk between metabolism and immune system. Herein, we provide a brief introduction to LXR and PPAR biology and review recent discoveries highlighting the importance of PPAR and LXR signaling in the modulation of normal and pathologic states of immunity. We also examine advances in our mechanistic understanding of how nuclear receptors impact immune system function and homeostasis. Finally, we discuss whether LXRs and PPARs could be pharmacologically manipulated to provide novel therapeutic approaches for modulation of the immune system under pathologic inflammation or in the context of allergic and autoimmune disease. © 2012 John Wiley & Sons A/S.

  10. JB-9322, a new selective histamine H2-receptor antagonist with potent gastric mucosal protective properties.

    Science.gov (United States)

    Palacios, B; Montero, M J; Sevilla, M A; Román, L S

    1995-05-01

    1. JB-9322 is a selective histamine H2-receptor antagonist with gastric antisecretory activity and mucosal protective properties. 2. The affinity of JB-9322 for the guinea-pig atria histamine H2-receptor was approximately 2 times greater than that of ranitidine. 3. In vivo, the ID50 value for the inhibition of gastric acid secretion in pylorus-ligated rats was 5.28 mg kg-1 intraperitoneally. JB-9322 also dose-dependently inhibited gastric juice volume and pepsin secretion. In gastric lumen-perfused rats, intravenous injection of JB-9322 dose-dependently reduced histamine-, pentagastrin- and carbachol-stimulated gastric acid secretion. 4. JB-9322 showed antiulcer activity against aspirin and indomethacin-induced gastric lesions and was more potent than ranitidine. 5. JB-9322 effectively inhibited macroscopic gastric haemorrhagic lesions induced by ethanol. Intraperitoneal injection was effective in preventing the lesions as well as oral treatment. The oral ID50 value for these lesions was 1.33 mg kg-1. By contrast, ranitidine (50 mg kg-1) failed to reduce these lesions. In addition, the protective effect of JB-9322 was independent of prostaglandin synthesis. 6. These results indicate that JB-9322 is a new antiulcer drug that exerts a potent cytoprotective effect in addition to its gastric antisecretory activity.

  11. CINPA1 Is an Inhibitor of Constitutive Androstane Receptor That Does Not Activate Pregnane X Receptor

    Science.gov (United States)

    Cherian, Milu T; Lin, Wenwei; Wu, Jing

    2015-01-01

    Constitutive androstane receptor (CAR) and pregnane X receptor (PXR) are xenobiotic sensors that enhance the detoxification and elimination of xenobiotics and endobiotics by modulating the expression of genes encoding drug-metabolizing enzymes and transporters. Elevated levels of drug-metabolizing enzymes and efflux transporters, resulting from CAR activation in various cancers, promote the elimination of chemotherapeutic agents, leading to reduced therapeutic effectiveness and acquired drug resistance. CAR inhibitors, in combination with existing chemotherapeutics, could therefore be used to attenuate multidrug resistance in cancers. Interestingly, all previously reported CAR inverse-agonists are also activators of PXR, rendering them mechanistically counterproductive in tissues where both these xenobiotic receptors are present and active. We used a directed high-throughput screening approach, followed by subsequent mechanistic studies, to identify novel, potent, and specific small-molecule CAR inhibitors that do not activate PXR. We describe here one such inhibitor, CINPA1 (CAR inhibitor not PXR activator 1), capable of reducing CAR-mediated transcription with an IC50 of ∼70 nM. CINPA1 1) is a specific xenobiotic receptor inhibitor and has no cytotoxic effects up to 30 µM; 2) inhibits CAR-mediated gene expression in primary human hepatocytes, where CAR is endogenously expressed; 3) does not alter the protein levels or subcellular localization of CAR; 4) increases corepressor and reduces coactivator interaction with the CAR ligand-binding domain in mammalian two-hybrid assays; and 5) disrupts CAR binding to the promoter regions of target genes in chromatin immunoprecipitation assays. CINPA1 could be used as a novel molecular tool for understanding CAR function. PMID:25762023

  12. CINPA1 is an inhibitor of constitutive androstane receptor that does not activate pregnane X receptor.

    Science.gov (United States)

    Cherian, Milu T; Lin, Wenwei; Wu, Jing; Chen, Taosheng

    2015-05-01

    Constitutive androstane receptor (CAR) and pregnane X receptor (PXR) are xenobiotic sensors that enhance the detoxification and elimination of xenobiotics and endobiotics by modulating the expression of genes encoding drug-metabolizing enzymes and transporters. Elevated levels of drug-metabolizing enzymes and efflux transporters, resulting from CAR activation in various cancers, promote the elimination of chemotherapeutic agents, leading to reduced therapeutic effectiveness and acquired drug resistance. CAR inhibitors, in combination with existing chemotherapeutics, could therefore be used to attenuate multidrug resistance in cancers. Interestingly, all previously reported CAR inverse-agonists are also activators of PXR, rendering them mechanistically counterproductive in tissues where both these xenobiotic receptors are present and active. We used a directed high-throughput screening approach, followed by subsequent mechanistic studies, to identify novel, potent, and specific small-molecule CAR inhibitors that do not activate PXR. We describe here one such inhibitor, CINPA1 (CAR inhibitor not PXR activator 1), capable of reducing CAR-mediated transcription with an IC50 of ∼70 nM. CINPA1 1) is a specific xenobiotic receptor inhibitor and has no cytotoxic effects up to 30 µM; 2) inhibits CAR-mediated gene expression in primary human hepatocytes, where CAR is endogenously expressed; 3) does not alter the protein levels or subcellular localization of CAR; 4) increases corepressor and reduces coactivator interaction with the CAR ligand-binding domain in mammalian two-hybrid assays; and 5) disrupts CAR binding to the promoter regions of target genes in chromatin immunoprecipitation assays. CINPA1 could be used as a novel molecular tool for understanding CAR function. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

  13. Transcriptional activation by the thyroid hormone receptor through ligand-dependent receptor recruitment and chromatin remodelling.

    Science.gov (United States)

    Grøntved, Lars; Waterfall, Joshua J; Kim, Dong Wook; Baek, Songjoon; Sung, Myong-Hee; Zhao, Li; Park, Jeong Won; Nielsen, Ronni; Walker, Robert L; Zhu, Yuelin J; Meltzer, Paul S; Hager, Gordon L; Cheng, Sheue-yann

    2015-04-28

    A bimodal switch model is widely used to describe transcriptional regulation by the thyroid hormone receptor (TR). In this model, the unliganded TR forms stable, chromatin-bound complexes with transcriptional co-repressors to repress transcription. Binding of hormone dissociates co-repressors and facilitates recruitment of co-activators to activate transcription. Here we show that in addition to hormone-independent TR occupancy, ChIP-seq against endogenous TR in mouse liver tissue demonstrates considerable hormone-induced TR recruitment to chromatin associated with chromatin remodelling and activated gene transcription. Genome-wide footprinting analysis using DNase-seq provides little evidence for TR footprints both in the absence and presence of hormone, suggesting that unliganded TR engagement with repressive complexes on chromatin is, similar to activating receptor complexes, a highly dynamic process. This dynamic and ligand-dependent interaction with chromatin is likely shared by all steroid hormone receptors regardless of their capacity to repress transcription in the absence of ligand.

  14. Modulation of cannabinoid receptor activation as a neuroprotective strategy for EAE and stroke.

    Science.gov (United States)

    Zhang, Ming; Martin, Billy R; Adler, Martin W; Razdan, Raj J; Kong, Weimin; Ganea, Doina; Tuma, Ronald F

    2009-06-01

    Recognition of the importance of the endocannabinoid system in both homeostasis and pathologic responses raised interest recently in the development of therapeutic agents based on this system. The CB(2) receptor, a component of the endocannabinoid system, has significant influence on immune function and inflammatory responses. Inflammatory responses are major contributors to central nervous system (CNS) injury in a variety of diseases. In this report, we present evidence that activation of CB(2) receptors, by selective CB(2) agonists, reduces inflammatory responses that contribute to CNS injury. The studies demonstrate neuroprotective effects in experimental autoimmune encephalomyelitis, a model of multiple sclerosis, and in a murine model of cerebral ischemia/reperfusion injury. In both cases, CB(2) receptor activation results in reduced white cell rolling and adhesion to cerebral microvessels, a reduction in immune cell invasion, and improved neurologic function after insult. In addition, administration of the CB(1) antagonist SR141716A reduces infarct size following ischemia/reperfusion injury. Administration of both a selective CB(2) agonist and a CB(1) antagonist has the unique property of increasing blood flow to the brain during the occlusion period, suggesting an effect on collateral blood flow. In summary, selective CB(2) receptor agonists and CB(1) receptor antagonists have significant potential for neuroprotection in animal models of two devastating diseases that currently lack effective treatment options.

  15. Reduced beta-adrenergic receptor activation decreases G-protein expression and beta-adrenergic receptor kinase activity in porcine heart.

    OpenAIRE

    Ping, P; Gelzer-Bell, R; Roth, D A; Kiel, D; Insel, P A; Hammond, H K

    1995-01-01

    To determine whether beta-adrenergic receptor agonist activation influences guanosine 5'-triphosphate-binding protein (G-protein) expression and beta-adrenergic receptor kinase activity in the heart, we examined the effects of chronic beta 1-adrenergic receptor antagonist treatment (bisoprolol, 0.2 mg/kg per d i.v., 35 d) on components of the myocardial beta-adrenergic receptor-G-protein-adenylyl cyclase pathway in porcine myocardium. Three novel alterations in cardiac adrenergic signaling as...

  16. Activation of peroxisome proliferator-activated receptors (PPARs) by their ligands and protein kinase A activators

    Science.gov (United States)

    Lazennec, Gwendal; Canaple, Laurence; Saugy, Damien; Wahli, Walter

    2000-01-01

    The nuclear peroxisome proliferator-activated receptors (PPARs) α, β and γ activate the transcription of multiple genes involved in lipid metabolism. Several natural and synthetic ligands have been identified for each PPAR isotype but little is known about the phosphorylation state of these receptors. We show here that activators of protein kinase A (PKA) can enhance mouse PPAR activity in the absence and the presence of exogenous ligands in transient transfection experiments. The activation function 1 (AF-1) of PPARs was dispensable for transcriptional enhancement, whereas the activation function 2 (AF-2) was required for this effect. We also show that several domains of PPAR can be phosphorylated by PKA in vitro. Moreover, gel experiments suggest that PKA stabilizes binding of the liganded PPAR to DNA. PKA inhibitors decreased not only the kinase dependent induction of PPARs but also their ligand-dependent induction, suggesting that the ligands may also mobilize the PKA pathway to lead to maximal transcriptional induction by PPARs. Moreover, comparing PPARα KO with PPARα wild-type mice, we show that the expression of the ACO gene can be regulated by PKA-activated PPARα in liver. These data demonstrate that the PKA pathway is an important modulator of PPAR activity and we propose a model associating this pathway in the control of fatty acid β-oxidation under conditions of fasting, stress and exercise. PMID:11117527

  17. The cannabinoid receptor type 2 as mediator of mesenchymal stromal cell immunosuppressive properties.

    Directory of Open Access Journals (Sweden)

    Francesca Rossi

    Full Text Available Mesenchymal stromal cells are non-hematopoietic, multipotent progenitor cells producing cytokines, chemokines, and extracellular matrix proteins that support hematopoietic stem cell survival and engraftment, influence immune effector cell development, maturation, and function, and inhibit alloreactive T-cell responses. The immunosuppressive properties of human mesenchymal stromal cells have attracted much attention from immunologists, stem cell biologists and clinicians. Recently, the presence of the endocannabinoid system in hematopoietic and neural stem cells has been demonstrated. Endocannabinoids, mainly acting through the cannabinoid receptor subtype 2, are able to modulate cytokine release and to act as immunosuppressant when added to activated T lymphocytes. In the present study, we have investigated, through a multidisciplinary approach, the involvement of the endocannabinoids in migration, viability and cytokine release of human mesenchymal stromal cells. We show, for the first time, that cultures of human mesenchymal stromal cells express all of the components of the endocannabinoid system, suggesting a potential role for the cannabinoid CB2 receptor as a mediator of anti-inflammatory properties of human mesenchymal stromal cells, as well as of their survival pathways and their capability to home and migrate towards endocannabinoid sources.

  18. Common structural basis for constitutive activity of the ghrelin receptor family

    DEFF Research Database (Denmark)

    Holst, Birgitte; Holliday, Nicholas D; Bach, Anders

    2004-01-01

    Three members of the ghrelin receptor family were characterized in parallel: the ghrelin receptor, the neurotensin receptor 2 and the orphan receptor GPR39. In transiently transfected COS-7 and human embryonic kidney 293 cells, all three receptors displayed a high degree of ligand......-independent signaling activity. The structurally homologous motilin receptor served as a constitutively silent control; upon agonist stimulation, however, it signaled with a similar efficacy to the three related receptors. The constitutive activity of the ghrelin receptor and of neurotensin receptor 2 through the G...... demonstrated that the epitope-tagged ghrelin receptor was constitutively internalized but could be trapped at the cell surface by an inverse agonist, whereas GPR39 remained at the cell surface. Mutational analysis showed that the constitutive activity of both the ghrelin receptor and GPR39 could systematically...

  19. Peroxisome Proliferator-Activated Receptor Alpha Target Genes

    Directory of Open Access Journals (Sweden)

    Maryam Rakhshandehroo

    2010-01-01

    Full Text Available The peroxisome proliferator-activated receptor alpha (PPARα is a ligand-activated transcription factor involved in the regulation of a variety of processes, ranging from inflammation and immunity to nutrient metabolism and energy homeostasis. PPARα serves as a molecular target for hypolipidemic fibrates drugs which bind the receptor with high affinity. Furthermore, PPARα binds and is activated by numerous fatty acids and fatty acid-derived compounds. PPARα governs biological processes by altering the expression of a large number of target genes. Accordingly, the specific role of PPARα is directly related to the biological function of its target genes. Here, we present an overview of the involvement of PPARα in lipid metabolism and other pathways through a detailed analysis of the different known or putative PPARα target genes. The emphasis is on gene regulation by PPARα in liver although many of the results likely apply to other organs and tissues as well.

  20. Glycine Receptor α2 Subunit Activation Promotes Cortical Interneuron Migration

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    Ariel Avila

    2013-08-01

    Full Text Available Glycine receptors (GlyRs are detected in the developing CNS before synaptogenesis, but their function remains elusive. This study demonstrates that functional GlyRs are expressed by embryonic cortical interneurons in vivo. Furthermore, genetic disruption of these receptors leads to interneuron migration defects. We discovered that extrasynaptic activation of GlyRs containing the α2 subunit in cortical interneurons by endogenous glycine activates voltage-gated calcium channels and promotes calcium influx, which further modulates actomyosin contractility to fine-tune nuclear translocation during migration. Taken together, our data highlight the molecular events triggered by GlyR α2 activation that control cortical tangential migration during embryogenesis.

  1. Environmental phthalate monoesters activate pregnane X receptor-mediated transcription

    International Nuclear Information System (INIS)

    Hurst, Christopher H.; Waxman, David J.

    2004-01-01

    Phthalate esters, widely used as plasticizers in the manufacture of products made of polyvinyl chloride, induce reproductive and developmental toxicities in rodents. The mechanism that underlies these effects of phthalate exposure, including the potential role of members of the nuclear receptor superfamily, is not known. The present study investigates the effects of phthalates on the pregnane X receptor (PXR), which mediates the induction of enzymes involved in steroid metabolism and xenobiotic detoxification. The ability of phthalate monoesters to activate PXR-mediated transcription was assayed in a HepG2 cell reporter assay following transfection with mouse PXR (mPXR), human PXR (hPXR), or the hPXR allelic variants V140M, D163G, and A370T. Mono-2-ethylhexyl phthalate (MEHP) increased the transcriptional activity of both mPXR and hPXR (5- and 15-fold, respectively) with EC 50 values of 7-8 μM. mPXR and hPXR were also activated by monobenzyl phthalate (MBzP, up to 5- to 6-fold) but were unresponsive to monomethyl phthalate and mono-n-butyl phthalate (M(n)BP) at the highest concentrations tested (300 μM). hPXR-V140M and hPXR-A370T exhibited patterns of phthalate responses similar to the wild-type receptor. By contrast, hPXR-D163G was unresponsive to all phthalate monoesters tested. Further studies revealed that hPXR-D163G did respond to rifampicin, but required approximately 40-fold higher concentrations than wild-type receptor, suggesting that the ligand-binding domain D163G variant has impaired ligand-binding activity. The responsiveness of PXR to activation by phthalate monoesters demonstrated here suggests that these ubiquitous environmental chemicals may, in part, exhibit their endocrine disruptor activities by altering PXR-regulated steroid hormone metabolism with potential adverse health effects in exposed individuals

  2. Modulation of the constitutive activity of the ghrelin receptor by use of pharmacological tools and mutagenesis.

    Science.gov (United States)

    Mokrosiński, Jacek; Holst, Birgitte

    2010-01-01

    Ghrelin and its receptor are important regulators of metabolic functions, including appetite, energy expenditure, fat accumulation, and growth hormone (GH) secretion. The ghrelin receptor is characterized by an ability to signal even without any ligand present with approximately 50% of the maximally ghrelin-induced efficacy-a feature that may have important physiological implications. The high basal signaling can be modulated either by administration of specific ligands or by engineering of mutations in the receptor structure. [D-Arg(1), D-Phe(5), D-Trp(7,9), Leu(11)]-substance P was the first inverse agonist to be identified for the ghrelin receptor, and this peptide has been used as a starting point for identification of the structural requirements for inverse agonist properties in the ligand. The receptor binding core motif was identified as D-Trp-Phe-D-Trp-Leu-Leu, and elongation of this peptide in the amino-terminal end determined the efficacy. Attachment of a positively charged amino acid was responsible for full inverse agonism, whereas an alanin converted the peptide into a partial agonist. Importantly, by use of mutational mapping of the residues critical for the modified D-Trp-Phe-D-Trp-Leu-Leu peptides, it was found that space-generating mutations in the deeper part of the receptor improved inverse agonism, whereas similar mutations located in the more extracellular part improved agonism. Modulation of the basal signaling by mutations in the receptor structure is primarily obtained by substitutions in an aromatic cluster that keep TMs VI and VII in close proximity to TM III and thus stabilize the active conformation. Also, substitution of a Phe in TM V is crucial for the high basal activity of the receptor as this residue serves as a partner for Trp VI:13 in the active conformation. It is suggested that inverse agonist and antagonist against the ghrelin receptor provide an interesting possibility in the development of drugs for treatment of obesity and

  3. How Far Does a Receptor Influence Vibrational Properties of an Odorant?

    Science.gov (United States)

    Reese, Anna; List, Nanna Holmgaard; Kongsted, Jacob; Solov'yov, Ilia A

    2016-01-01

    The biophysical mechanism of the sense of smell, or olfaction, is still highly debated. The mainstream explanation argues for a shape-based recognition of odorant molecules by olfactory receptors, while recent investigations suggest the primary olfactory event to be triggered by a vibrationally-assisted electron transfer reaction. We consider this controversy by studying the influence of a receptor on the vibrational properties of an odorant in atomistic details as the coupling between electronic degrees of freedom of the receptor and the vibrations of the odorant is the key parameter of the vibrationally-assisted electron transfer. Through molecular dynamics simulations we elucidate the binding specificity of a receptor towards acetophenone odorant. The vibrational properties of acetophenone inside the receptor are then studied by the polarizable embedding density functional theory approach, allowing to quantify protein-odorant interactions. Finally, we judge whether the effects of the protein provide any indications towards the existing theories of olfaction.

  4. Functional antagonistic properties of clozapine at the 5-HT3 receptor.

    Science.gov (United States)

    Hermann, B; Wetzel, C H; Pestel, E; Zieglgänsberger, W; Holsboer, F; Rupprecht, R

    1996-08-23

    The atypical neuroleptic clozapine is thought to exert its psychopharmacological actions through a variety of neurotransmitter receptors. It binds preferentially to D4 and 5-HT2 receptors; however, little is known on it's interaction with the 5-HT3 receptor. Using a cell line stably expressing the 5-HT3 receptor, whole-cell voltage-clamp analysis revealed functional antagonistic properties of clozapine at low nanomolar concentrations in view of a binding affinity in the upper nanomolar range. Because the concentration of clozapine required for an interaction with the 5-HT3 receptor can be achieved with therapeutical doses, functional antagonistic properties at this ligand-gated ion channel may contribute to its unique psychopharmacological profile.

  5. The Growth Hormone Receptor: Mechanism of Receptor Activation, Cell Signaling, and Physiological Aspects

    Directory of Open Access Journals (Sweden)

    Farhad Dehkhoda

    2018-02-01

    Full Text Available The growth hormone receptor (GHR, although most well known for regulating growth, has many other important biological functions including regulating metabolism and controlling physiological processes related to the hepatobiliary, cardiovascular, renal, gastrointestinal, and reproductive systems. In addition, growth hormone signaling is an important regulator of aging and plays a significant role in cancer development. Growth hormone activates the Janus kinase (JAK–signal transducer and activator of transcription (STAT signaling pathway, and recent studies have provided a new understanding of the mechanism of JAK2 activation by growth hormone binding to its receptor. JAK2 activation is required for growth hormone-mediated activation of STAT1, STAT3, and STAT5, and the negative regulation of JAK–STAT signaling comprises an important step in the control of this signaling pathway. The GHR also activates the Src family kinase signaling pathway independent of JAK2. This review covers the molecular mechanisms of GHR activation and signal transduction as well as the physiological consequences of growth hormone signaling.

  6. Neurohumoral activation in heart failure: the role of adrenergic receptors

    Directory of Open Access Journals (Sweden)

    Patricia C. Brum

    2006-09-01

    Full Text Available Heart failure (HF is a common endpoint for many forms of cardiovascular disease and a significant cause of morbidity and mortality. The development of end-stage HF often involves an initial insult to the myocardium that reduces cardiac output and leads to a compensatory increase in sympathetic nervous system activity. Acutely, the sympathetic hyperactivity through the activation of beta-adrenergic receptors increases heart rate and cardiac contractility, which compensate for decreased cardiac output. However, chronic exposure of the heart to elevated levels of catecholamines released from sympathetic nerve terminals and the adrenal gland may lead to further pathologic changes in the heart, resulting in continued elevation of sympathetic tone and a progressive deterioration in cardiac function. On a molecular level, altered beta-adrenergic receptor signaling plays a pivotal role in the genesis and progression of HF. beta-adrenergic receptor number and function are decreased, and downstream mechanisms are altered. In this review we will present an overview of the normal beta-adrenergic receptor pathway in the heart and the consequences of sustained adrenergic activation in HF. The myopathic potential of individual components of the adrenergic signaling will be discussed through the results of research performed in genetic modified animals. Finally, we will discuss the potential clinical impact of beta-adrenergic receptor gene polymorphisms for better understanding the progression of HF.A insuficiência cardíaca (IC é a via final comum da maioria das doenças cardiovasculares e uma das maiores causas de morbi-mortalidade. O desenvolvimento do estágio final da IC freqüentemente envolve um insulto inicial do miocárdio, reduzindo o débito cardíaco e levando ao aumento compensatório da atividade do sistema nervoso simpático (SNS. Existem evidências de que apesar da exposição aguda ser benéfica, exposições crônicas a elevadas concentra

  7. Mechanism of A2 adenosine receptor activation. I. Blockade of A2 adenosine receptors by photoaffinity labeling

    International Nuclear Information System (INIS)

    Lohse, M.J.; Klotz, K.N.; Schwabe, U.

    1991-01-01

    It has previously been shown that covalent incorporation of the photoreactive adenosine derivative (R)-2-azido-N6-p-hydroxy-phenylisopropyladenosine [(R)-AHPIA] into the A1 adenosine receptor of intact fat cells leads to a persistent activation of this receptor, resulting in a reduction of cellular cAMP levels. In contrast, covalent incorporation of (R)-AHPIA into human platelet membranes, which contain only stimulatory A2 adenosine receptors, reduces adenylate cyclase stimulation via these receptors. This effect of (R)-AHPIA is specific for the A2 receptor and can be prevented by the adenosine receptor antagonist theophylline. Binding studies indicate that up to 90% of A2 receptors can be blocked by photoincorporation of (R)-AHPIA. However, the remaining 10-20% of A2 receptors are sufficient to mediate an adenylate cyclase stimulation of up to 50% of the control value. Similarly, the activation via these 10-20% of receptors occurs with a half-life that is only 2 times longer than that in control membranes. This indicates the presence of a receptor reserve, with respect to both the extent and the rate of adenylate cyclase stimulation. These observations require a modification of the models of receptor-adenylate cyclase coupling

  8. Functional relevance of G-protein-coupled-receptor-associated proteins, exemplified by receptor-activity-modifying proteins (RAMPs).

    Science.gov (United States)

    Fischer, J A; Muff, R; Born, W

    2002-08-01

    The calcitonin (CT) receptor (CTR) and the CTR-like receptor (CRLR) are close relatives within the type II family of G-protein-coupled receptors, demonstrating sequence identity of 50%. Unlike the interaction between CT and CTR, receptors for the related hormones and neuropeptides amylin, CT-gene-related peptide (CGRP) and adrenomedullin (AM) require one of three accessory receptor-activity-modifying proteins (RAMPs) for ligand recognition. An amylin/CGRP receptor is revealed when CTR is co-expressed with RAMP1. When complexed with RAMP3, CTR interacts with amylin alone. CRLR, initially classed as an orphan receptor, is a CGRP receptor when co-expressed with RAMP1. The same receptor is specific for AM in the presence of RAMP2. Together with human RAMP3, CRLR defines an AM receptor, and with mouse RAMP3 it is a low-affinity CGRP/AM receptor. CTR-RAMP1, antagonized preferentially by salmon CT-(8-32) and not by CGRP-(8-37), and CRLR-RAMP1, antagonized by CGRP-(8-37), are two CGRP receptor isotypes. Thus amylin and CGRP interact specifically with heterodimeric complexes between CTR and RAMP1 or RAMP3, and CGRP and AM interact with complexes between CRLR and RAMP1, RAMP2 or RAMP3.

  9. DNA binding properties of dioxin receptors in wild-type and mutant mouse hepatoma cells

    International Nuclear Information System (INIS)

    Cuthill, S.; Poellinger, L.

    1988-01-01

    The current model of action of 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) entails stimulation of target gene transcription via the formation of dioxin-receptor complexes and subsequent accumulation of the complexes within the cell nucleus. Here, the authors have analyzed the DNA binding properties of the dioxin receptor in wild-type mouse hepatoma (Hepa 1c1c7) cells and a class of nonresponsive mutant cells which fail to accumulate dioxin-receptor complexes within the nucleus in vivo. In vitro, both the wild-type and mutant [ 3 H]dioxin-receptor complexes exhibited low affinity for DNA-cellulose (5-8% and around 4% retention, respectively) in the absence of prior biochemical manipulations. However, following chromatography on heparin-Sepharose, the wild-type but not the mutant dioxin receptor was transformed to a species with an increased affinity for DNA (40-50% retention on DNA-cellulose). The gross molecular structure of the mutant, non DNA binding dioxin receptor did not appear to be altered as compared to that of the wild-type receptor. These results imply that the primary deficiency in the mutant dioxin receptor form may reside at the DNA binding level and that, in analogy to steroid hormone receptors, DNA binding of the receptor may be an essential step in the regulation of target gene transcription by dioxin

  10. P2X7 receptor activates extracellular signal-regulated kinases ERK1 and ERK2 independently of Ca2+ influx

    DEFF Research Database (Denmark)

    Amstrup, Jan; Novak, Ivana

    2003-01-01

    P2X7 nucleotide receptors modulate a spectrum of cellular events in various cells including epithelia, such as exocrine pancreas. Although the pharmacology and channel properties of the P2X7 receptors have been studied intensively, signal transduction pathways are relatively unknown. In this study...... we applied a heterologous expression system of rat P2X7 receptors in HEK-293 cells. We followed the receptor expression and function using the enhanced green fluorescent protein (EGFP) tag, activation of intracellular proteins and increases in cellular Ca2+. EGFP-P2X7 receptors localized...... to the plasma membrane, clusters within the membrane and intracellularly. Stimulation of P2X7 receptors in HEK-293 cells led to an activation of extracellular signal-regulated kinases ERK1 and ERK2 and this activation was seen after just 1 min of stimulation with ATP. Using C- and N-terminal P2X7-receptor...

  11. Activation of Penile Proadipogenic Peroxisome Proliferator-Activated Receptor with an Estrogen: Interaction with Estrogen Receptor Alpha during Postnatal Development

    Directory of Open Access Journals (Sweden)

    Mahmoud M. Mansour

    2008-01-01

    Full Text Available Exposure to the estrogen receptor alpha (ER ligand diethylstilbesterol (DES between neonatal days 2 to 12 induces penile adipogenesis and adult infertility in rats. The objective of this study was to investigate the in vivo interaction between DES-activated ER and the proadipogenic transcription factor peroxisome proliferator-activated receptor gamma (PPAR. Transcripts for PPARs , , and and 1a splice variant were detected in Sprague-Dawley normal rat penis with PPAR predominating. In addition, PPAR1b and PPAR2 were newly induced by DES. The PPAR transcripts were significantly upregulated with DES and reduced by antiestrogen ICI 182, 780. At the cellular level, PPAR protein was detected in urethral transitional epithelium and stromal, endothelial, neuronal, and smooth muscular cells. Treatment with DES activated ER and induced adipocyte differentiation in corpus cavernosum penis. Those adipocytes exhibited strong nuclear PPAR expression. These results suggest a biological overlap between PPAR and ER and highlight a mechanism for endocrine disruption.

  12. Endogenous activation of adenosine A(1) receptors accelerates ischemic suppression of spontaneous electrocortical activity

    DEFF Research Database (Denmark)

    Ilie, Andrei; Ciocan, Dragos; Zagrean, Ana-Maria

    2006-01-01

    Cerebral ischemia induces a rapid suppression of spontaneous brain rhythms prior to major alterations in ionic homeostasis. It was found in vitro during ischemia that the rapidly formed adenosine, resulting from the intracellular breakdown of ATP, may inhibit synaptic transmission via the A(1......) receptor subtype. The link between endogenous A(1) receptor activation during ischemia and the suppression of spontaneous electrocortical activity has not yet been established in the intact brain. The aim of this study was to investigate in vivo the effects of A(1) receptor antagonism by 8-cyclopentyl-1...

  13. NMDA receptor blockade in the prelimbic cortex activates the mesolimbic system and dopamine-dependent opiate reward signaling.

    Science.gov (United States)

    Tan, Huibing; Rosen, Laura G; Ng, Garye A; Rushlow, Walter J; Laviolette, Steven R

    2014-12-01

    N-Methyl-D-aspartate (NMDA) receptors in the medial prefrontal cortex (mPFC) are involved in opiate reward processing and modulate sub-cortical dopamine (DA) activity. NMDA receptor blockade in the prelimbic (PLC) division of the mPFC strongly potentiates the rewarding behavioural properties of normally sub-reward threshold doses of opiates. However, the possible functional interactions between cortical NMDA and sub-cortical DAergic motivational neural pathways underlying these effects are not understood. This study examines how NMDA receptor modulation in the PLC influences opiate reward processing via interactions with sub-cortical DAergic transmission. We further examined whether direct intra-PLC NMDA receptor modulation may activate DA-dependent opiate reward signaling via interactions with the ventral tegmental area (VTA). Using an unbiased place conditioning procedure (CPP) in rats, we performed bilateral intra-PLC microinfusions of the competitive NMDA receptor antagonist, (2R)-amino-5-phosphonovaleric acid (AP-5), prior to behavioural morphine place conditioning and challenged the rewarding effects of morphine with DA receptor blockade. We next examined the effects of intra-PLC NMDA receptor blockade on the spontaneous activity patterns of presumptive VTA DA or GABAergic neurons, using single-unit, extracellular in vivo neuronal recordings. We show that intra-PLC NMDA receptor blockade strongly activates sub-cortical DA neurons within the VTA while inhibiting presumptive non-DA GABAergic neurons. Behaviourally, NMDA receptor blockade activates a DA-dependent opiate reward system, as pharmacological blockade of DA transmission blocked morphine reward only in the presence of intra-PLC NMDA receptor antagonism. These findings demonstrate a cortical NMDA-mediated mechanism controlling mesolimbic DAergic modulation of opiate reward processing.

  14. Cockroach GABAB receptor subtypes: molecular characterization, pharmacological properties and tissue distribution.

    Science.gov (United States)

    Blankenburg, S; Balfanz, S; Hayashi, Y; Shigenobu, S; Miura, T; Baumann, O; Baumann, A; Blenau, W

    2015-01-01

    γ-aminobutyric acid (GABA) is the predominant inhibitory neurotransmitter in the central nervous system (CNS). Its effects are mediated by either ionotropic GABAA receptors or metabotropic GABAB receptors. GABAB receptors regulate, via Gi/o G-proteins, ion channels, and adenylyl cyclases. In humans, GABAB receptor subtypes are involved in the etiology of neurologic and psychiatric disorders. In arthropods, however, these members of the G-protein-coupled receptor family are only inadequately characterized. Interestingly, physiological data have revealed important functions of GABAB receptors in the American cockroach, Periplaneta americana. We have cloned cDNAs coding for putative GABAB receptor subtypes 1 and 2 of P. americana (PeaGB1 and PeaGB2). When both receptor proteins are co-expressed in mammalian cells, activation of the receptor heteromer with GABA leads to a dose-dependent decrease in cAMP production. The pharmacological profile differs from that of mammalian and Drosophila GABAB receptors. Western blot analyses with polyclonal antibodies have revealed the expression of PeaGB1 and PeaGB2 in the CNS of the American cockroach. In addition to the widespread distribution in the brain, PeaGB1 is expressed in salivary glands and male accessory glands. Notably, PeaGB1-like immunoreactivity has been detected in the GABAergic salivary neuron 2, suggesting that GABAB receptors act as autoreceptors in this neuron. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. GRK2 Constitutively Governs Peripheral Delta Opioid Receptor Activity

    Directory of Open Access Journals (Sweden)

    Allison Doyle Brackley

    2016-09-01

    Full Text Available Opioids remain the standard for analgesic care; however, adverse effects of systemic treatments contraindicate long-term administration. While most clinical opioids target mu opioid receptors (MOR, those that target the delta class (DOR also demonstrate analgesic efficacy. Furthermore, peripherally restrictive opioids represent an attractive direction for analgesia. However, opioid receptors including DOR are analgesically incompetent in the absence of inflammation. Here, we report that G protein-coupled receptor kinase 2 (GRK2 naively associates with plasma membrane DOR in peripheral sensory neurons to inhibit analgesic agonist efficacy. This interaction prevents optimal Gβ subunit association with the receptor, thereby reducing DOR activity. Importantly, bradykinin stimulates GRK2 movement away from DOR and onto Raf kinase inhibitory protein (RKIP. protein kinase C (PKC-dependent RKIP phosphorylation induces GRK2 sequestration, restoring DOR functionality in sensory neurons. Together, these results expand the known function of GRK2, identifying a non-internalizing role to maintain peripheral DOR in an analgesically incompetent state.

  16. Sympatho-inhibitory properties of various AT1 receptor antagonists

    NARCIS (Netherlands)

    Balt, Jippe C.; Mathy, Marie-Jeanne; Pfaffendorf, Martin; van Zwieten, Peter A.

    2002-01-01

    It is well known that angiotensin II (Ang II) can facilitate the effects of sympathetic neurotransmission. In the present study, using various experimental models, we investigated the inhibitory effects of several Ang II subtype 1 receptor (AT1) antagonists on this Ang II-induced facilitation. We

  17. Identification of an Activating Chicken Ig-like Receptor Recognizing Avian Influenza Viruses

    NARCIS (Netherlands)

    Jansen, Christine A; van Haarlem, Daphne A; Sperling, Beatrice; van Kooten, Peter J; de Vries, Erik; Viertlboeck, Birgit C; Vervelde, Lonneke; Göbel, Thomas W

    2016-01-01

    Chicken Ig-like receptors (CHIRs) represent a multigene family encoded by the leukocyte receptor complex that encodes a variety of receptors that are subdivided into activating CHIR-A, inhibitory CHIR-B, and bifunctional CHIR-AB. Apart from CHIR-AB, which functions as an Fc receptor, CHIR ligands

  18. In vitro binding and receptor-mediated activity of terlipressin at vasopressin receptors V1 and V2.

    Science.gov (United States)

    Jamil, Khurram; Pappas, Stephen Chris; Devarakonda, Krishna R

    2018-01-01

    Terlipressin, a synthetic, systemic vasoconstrictor with selective activity at vasopressin-1 (V 1 ) receptors, is a pro-drug for the endogenous/natural porcine hormone [Lys 8 ]-vasopressin (LVP). We investigated binding and receptor-mediated cellular activities of terlipressin, LVP, and endogenous human hormone [Arg 8 ]-vasopressin (AVP) at V 1 and vasopressin-2 (V 2 ) receptors. Cell membrane homogenates of Chinese hamster ovary cells expressing human V 1 and V 2 receptors were used in competitive binding assays to measure receptor-binding activity. These cells were used in functional assays to measure receptor-mediated cellular activity of terlipressin, LVP, and AVP. Binding was measured by [ 3 H]AVP counts, and the activity was measured by fluorometric detection of intracellular calcium mobilization (V 1 ) and cyclic adenosine monophosphate (V 2 ). Binding potency at V 1 and V 2 was AVP>LVP>terlipressin. LVP and terlipressin had approximately sixfold higher affinity for V 1 than for V 2 . Cellular activity potency was also AVP>LVP>terlipressin. Terlipressin was a partial agonist at V 1 and a full agonist at V 2 ; LVP was a full agonist at both V 1 and V 2 . The in vivo response to terlipressin is likely due to the partial V 1 agonist activity of terlipressin and full V 1 agonist activity of its metabolite, LVP. These results provide supportive evidence for previous findings and further establish terlipressin pharmacology for vasopressin receptors.

  19. Surface active monomers synthesis, properties, and application

    CERN Document Server

    Borzenkov, Mykola

    2014-01-01

    This brief includes information on the background?of and development of synthesis of various types of surface active monomers. The authors explain the importance of utilization of surface active monomers for creation of surface active polymers? and the various biomedical applications of such compounds . This brief introduces techniques for the synthesis of novel types of surface active monomers, their colloidal and polymerizable properties and application for needs of medicine and biology.

  20. Acute activation, desensitization and smoldering activation of human acetylcholine receptors.

    Directory of Open Access Journals (Sweden)

    Barbara G Campling

    Full Text Available The behavioral effects of nicotine and other nicotinic agonists are mediated by AChRs in the brain. The relative contribution of acute activation versus chronic desensitization of AChRs is unknown. Sustained "smoldering activation" occurs over a range of agonist concentrations at which activated and desensitized AChRs are present in equilibrium. We used a fluorescent dye sensitive to changes in membrane potential to examine the effects of acute activation and chronic desensitization by nicotinic AChR agonists on cell lines expressing human α4β2, α3β4 and α7 AChRs. We examined the effects of acute and prolonged application of nicotine and the partial agonists varenicline, cytisine and sazetidine-A on these AChRs. The range of concentrations over which nicotine causes smoldering activation of α4β2 AChRs was centered at 0.13 µM, a level found in smokers. However, nicotine produced smoldering activation of α3β4 and α7 AChRs at concentrations well above levels found in smokers. The α4β2 expressing cell line contains a mixture of two stoichiometries, namely (α4β22β2 and (α4β22α4. The (α4β22β2 stoichiometry is more sensitive to activation by nicotine. Sazetidine-A activates and desensitizes only this stoichiometry. Varenicline, cytisine and sazetidine-A were partial agonists on this mixture of α4β2 AChRs, but full agonists on α3β4 and α7 AChRs. It has been reported that cytisine and varenicline are most efficacious on the (α4β22α4 stoichiometry. In this study, we distinguish the dual effects of activation and desensitization of AChRs by these nicotinic agonists and define the range of concentrations over which smoldering activation can be sustained.

  1. Key structural features of nonsteroidal ligands for binding and activation of the androgen receptor.

    Science.gov (United States)

    Yin, Donghua; He, Yali; Perera, Minoli A; Hong, Seoung Soo; Marhefka, Craig; Stourman, Nina; Kirkovsky, Leonid; Miller, Duane D; Dalton, James T

    2003-01-01

    The purposes of the present studies were to examine the androgen receptor (AR) binding ability and in vitro functional activity of multiple series of nonsteroidal compounds derived from known antiandrogen pharmacophores and to investigate the structure-activity relationships (SARs) of these nonsteroidal compounds. The AR binding properties of sixty-five nonsteroidal compounds were assessed by a radioligand competitive binding assay with the use of cytosolic AR prepared from rat prostates. The AR agonist and antagonist activities of high-affinity ligands were determined by the ability of the ligand to regulate AR-mediated transcriptional activation in cultured CV-1 cells, using a cotransfection assay. Nonsteroidal compounds with diverse structural features demonstrated a wide range of binding affinity for the AR. Ten compounds, mainly from the bicalutamide-related series, showed a binding affinity superior to the structural pharmacophore from which they were derived. Several SARs regarding nonsteroidal AR binding were revealed from the binding data, including stereoisomeric conformation, steric effect, and electronic effect. The functional activity of high-affinity ligands ranged from antagonist to full agonist for the AR. Several structural features were found to be determinative of agonist and antagonist activities. The nonsteroidal AR agonists identified from the present studies provided a pool of candidates for further development of selective androgen receptor modulators (SARMs) for androgen therapy. Also, these studies uncovered or confirmed numerous important SARs governing AR binding and functional properties by nonsteroidal molecules, which would be valuable in the future structural optimization of SARMs.

  2. The prostaglandin EP1 receptor potentiates kainate receptor activation via a protein kinase C pathway and exacerbates status epilepticus

    Science.gov (United States)

    Rojas, Asheebo; Gueorguieva, Paoula; Lelutiu, Nadia; Quan, Yi; Shaw, Renee; Dingledine, Raymond

    2014-01-01

    Prostaglandin E2 (PGE2) regulates membrane excitability, synaptic transmission, plasticity, and neuronal survival. The consequences of PGE2 release following seizures has been the subject of much study. Here we demonstrate that the prostaglandin E2 receptor 1 (EP1, or Ptger1) modulates native kainate receptors, a family of ionotropic glutamate receptors widely expressed throughout the central nervous system. Global ablation of the EP1 gene in mice (EP1-KO) had no effect on seizure threshold after kainate injection but reduced the likelihood to enter status epilepticus. EP1-KO mice that did experience typical status epilepticus had reduced hippocampal neurodegeneration and a blunted inflammatory response. Further studies with native prostanoid and kainate receptors in cultured cortical neurons, as well as with recombinant prostanoid and kainate receptors expressed in Xenopus oocytes, demonstrated that EP1 receptor activation potentiates heteromeric but not homomeric kainate receptors via a second messenger cascade involving phospholipase C, calcium and protein kinase C. Three critical GluK5 C-terminal serines underlie the potentiation of the GluK2/GluK5 receptor by EP1 activation. Taken together, these results indicate that EP1 receptor activation during seizures, through a protein kinase C pathway, increases the probability of kainic acid induced status epilepticus, and independently promotes hippocampal neurodegeneration and a broad inflammatory response. PMID:24952362

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

    Science.gov (United States)

    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.

  4. Potential effects of curcumin on peroxisome proliferator-activated receptor-gamma in vitro and in vivo

    Science.gov (United States)

    Natural peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists are found in food and may be important for health through their anti-inflammatory properties. Curcumin (Cur) is a bright yellow spice, derived from the rhizome of Curcuma longa Linn. It has been shown to have many biologi...

  5. PAR1 activation affects the neurotrophic properties of Schwann cells.

    Science.gov (United States)

    Pompili, Elena; Fabrizi, Cinzia; Somma, Francesca; Correani, Virginia; Maras, Bruno; Schininà, Maria Eugenia; Ciraci, Viviana; Artico, Marco; Fornai, Francesco; Fumagalli, Lorenzo

    2017-03-01

    Protease-activated receptor-1 (PAR1) is the prototypic member of a family of four G-protein-coupled receptors that signal in response to extracellular proteases. In the peripheral nervous system, the expression and/or the role of PARs are still poorly investigated. High PAR1 mRNA expression was found in the rat dorsal root ganglia and the signal intensity of PAR1 mRNA increased in response to sciatic nerve transection. In the sciatic nerve, functional PAR1 receptor was reported at the level of non-compacted Schwann cell myelin microvilli of the nodes of Ranvier. Schwann cells are the principal population of glial cells of the peripheral nervous system which myelinate axons playing an important role during axonal regeneration and remyelination. The present study was undertaken in order to determine if the activation of PAR1 affects the neurotrophic properties of Schwann cells. Our results suggest that the stimulation of PAR1 could potentiate the Schwann cell ability to favour nerve regeneration. In fact, the conditioned medium obtained from Schwann cell cultures challenged with a specific PAR1 activating peptide (PAR1 AP) displays increased neuroprotective and neurotrophic properties with respect to the culture medium from untreated Schwann cells. The proteomic analysis of secreted proteins in untreated and PAR1 AP-treated Schwann cells allowed the identification of factors differentially expressed in the two samples. Some of them (such as macrophage migration inhibitory factor, matrix metalloproteinase-2, decorin, syndecan 4, complement C1r subcomponent, angiogenic factor with G patch and FHA domains 1) appear to be transcriptionally regulated after PAR1 AP treatment as shown by RT-PCR. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Implications of compound heterozygous insulin receptor mutations in congenital muscle fibre type disproportion myopathy for the receptor kinase activation

    DEFF Research Database (Denmark)

    Klein, H H; Müller, R; Vestergaard, H

    1999-01-01

    We studied insulin receptor kinase activation in two brothers with congenital muscle fibre type disproportion myopathy and compound heterozygous mutations of the insulin receptor gene, their parents, and their unaffected brother. In the father who has a heterozygote Arg1174-->Gln mutation, in sit...

  7. Urokinase-type plasminogen activator receptor (uPAR), tissue factor (TF) and epidermal growth factor receptor (EGFR)

    DEFF Research Database (Denmark)

    Christensen, Anders; Kiss, Katalin; Lelkaitis, Giedrius

    2017-01-01

    Background: Tumor-specific biomarkers are a prerequisite for the development of targeted imaging and therapy in oral squamous cell carcinoma (OSCC). urokinase-type Plasminogen Activator Receptor (uPAR), Tissue Factor (TF) and Epidermal Growth Factor Receptor (EGFR) are three biomarkers that exhib...... with a reduced survival. uPAR seems to be a prognostic biomarker in oral cancer....

  8. Nicotinic acetylcholine receptor: subunit structure, functional binding sites, and ion transport properties

    International Nuclear Information System (INIS)

    Raftery, M.A.; Dunn, S.M.J.; Conti-Tronconi, B.M.; Middlemas, D.S.; Crawford, R.D.

    1983-01-01

    The structure of the nicotinic acetylcholine receptor has been highly conserved during animal evolution, and in all the species and tissues studied so far, including mammals, it is a pseudosymmetric, pentameric complex of related subunits with very similar physical properties. All subunits of these nicotinic receptors were derived from a common ancestral gene, probably by way of gene duplications occurring very early in animal evolution. 45 refs., 8 figs., 2 tabs

  9. Methamphetamine Increases Locomotion and Dopamine Transporter Activity in Dopamine D5 Receptor-Deficient Mice

    OpenAIRE

    Hayashizaki, Seiji; Hirai, Shinobu; Ito, Yumi; Honda, Yoshiko; Arime, Yosefu; Sora, Ichiro; Okado, Haruo; Kodama, Tohru; Takada, Masahiko

    2013-01-01

    Dopamine regulates the psychomotor stimulant activities of amphetamine-like substances in the brain. The effects of dopamine are mediated through five known dopamine receptor subtypes in mammals. The functional relevance of D5 dopamine receptors in the central nervous system is not well understood. To determine the functional relevance of D5 dopamine receptors, we created D5 dopamine receptor-deficient mice and then used these mice to assess the roles of D5 dopamine receptors in the behaviora...

  10. Behavioral meaningful opioidergic stimulation activates kappa receptor gene expression

    International Nuclear Information System (INIS)

    Teodorov, E.; Ferrari, M.F.R.; Fior-Chadi, D.R.; Camarini, R.; Felício, L.F.

    2012-01-01

    The periaqueductal gray (PAG) has been reported to be a location for opioid regulation of pain and a potential site for behavioral selection in females. Opioid-mediated behavioral and physiological responses differ according to the activity of opioid receptor subtypes. The present study investigated the effects of the peripheral injection of the kappa-opioid receptor agonist U69593 into the dorsal subcutaneous region of animals on maternal behavior and on Oprk1 gene activity in the PAG of female rats. Female Wistar rats weighing 200-250 g at the beginning of the study were randomly divided into 2 groups for maternal behavior and gene expression experiments. On day 5, pups were removed at 7:00 am and placed in another home cage that was distant from their mother. Thirty minutes after removing the pups, the dams were treated with U69593 (0.15 mg/kg, sc) or 0.9% saline (up to 1 mL/kg) and after 30 min were evaluated in the maternal behavior test. Latencies in seconds for pup retrieval, grouping, crouching, and full maternal behavior were scored. The results showed that U69593 administration inhibited maternal behavior (P < 0.05) because a lower percentage of U69593 group dams showed retrieval of first pup, retrieving all pups, grouping, crouching and displaying full maternal behavior compared to the saline group. Opioid gene expression was evaluated using real-time reverse-transcription polymerase chain reaction (RT-PCR). A single injection of U69593 increased Oprk1 PAG expression in both virgin (P < 0.05) and lactating female rats (P < 0.01), with no significant effect on Oprm1 or Oprd1 gene activity. Thus, the expression of kappa-opioid receptors in the PAG may be modulated by single opioid receptor stimulation and behavioral meaningful opioidergic transmission in the adult female might occur simultaneously to specific changes in gene expression of kappa-opioid receptor subtype. This is yet another alert for the complex role of the opioid system in female

  11. Behavioral meaningful opioidergic stimulation activates kappa receptor gene expression

    Energy Technology Data Exchange (ETDEWEB)

    Teodorov, E. [Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, São Paulo, SP (Brazil); Ferrari, M.F.R. [Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP (Brazil); Fior-Chadi, D.R. [Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP (Brazil); Camarini, R. [Departamento de Farmacologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP (Brazil); Felício, L.F. [Departamento de Patologia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP (Brazil)

    2012-06-01

    The periaqueductal gray (PAG) has been reported to be a location for opioid regulation of pain and a potential site for behavioral selection in females. Opioid-mediated behavioral and physiological responses differ according to the activity of opioid receptor subtypes. The present study investigated the effects of the peripheral injection of the kappa-opioid receptor agonist U69593 into the dorsal subcutaneous region of animals on maternal behavior and on Oprk1 gene activity in the PAG of female rats. Female Wistar rats weighing 200-250 g at the beginning of the study were randomly divided into 2 groups for maternal behavior and gene expression experiments. On day 5, pups were removed at 7:00 am and placed in another home cage that was distant from their mother. Thirty minutes after removing the pups, the dams were treated with U69593 (0.15 mg/kg, sc) or 0.9% saline (up to 1 mL/kg) and after 30 min were evaluated in the maternal behavior test. Latencies in seconds for pup retrieval, grouping, crouching, and full maternal behavior were scored. The results showed that U69593 administration inhibited maternal behavior (P < 0.05) because a lower percentage of U69593 group dams showed retrieval of first pup, retrieving all pups, grouping, crouching and displaying full maternal behavior compared to the saline group. Opioid gene expression was evaluated using real-time reverse-transcription polymerase chain reaction (RT-PCR). A single injection of U69593 increased Oprk1 PAG expression in both virgin (P < 0.05) and lactating female rats (P < 0.01), with no significant effect on Oprm1 or Oprd1 gene activity. Thus, the expression of kappa-opioid receptors in the PAG may be modulated by single opioid receptor stimulation and behavioral meaningful opioidergic transmission in the adult female might occur simultaneously to specific changes in gene expression of kappa-opioid receptor subtype. This is yet another alert for the complex role of the opioid system in female

  12. Behavioral meaningful opioidergic stimulation activates kappa receptor gene expression

    Directory of Open Access Journals (Sweden)

    E. Teodorov

    2012-10-01

    Full Text Available The periaqueductal gray (PAG has been reported to be a location for opioid regulation of pain and a potential site for behavioral selection in females. Opioid-mediated behavioral and physiological responses differ according to the activity of opioid receptor subtypes. The present study investigated the effects of the peripheral injection of the kappa-opioid receptor agonist U69593 into the dorsal subcutaneous region of animals on maternal behavior and on Oprk1 gene activity in the PAG of female rats. Female Wistar rats weighing 200-250 g at the beginning of the study were randomly divided into 2 groups for maternal behavior and gene expression experiments. On day 5, pups were removed at 7:00 am and placed in another home cage that was distant from their mother. Thirty minutes after removing the pups, the dams were treated with U69593 (0.15 mg/kg, sc or 0.9% saline (up to 1 mL/kg and after 30 min were evaluated in the maternal behavior test. Latencies in seconds for pup retrieval, grouping, crouching, and full maternal behavior were scored. The results showed that U69593 administration inhibited maternal behavior (P < 0.05 because a lower percentage of kappa group dams showed retrieval of first pup, retrieving all pups, grouping, crouching and displaying full maternal behavior compared to the saline group. Opioid gene expression was evaluated using real-time reverse-transcription polymerase chain reaction (RT-PCR. A single injection of U69593 increased Oprk1 PAG expression in both virgin (P < 0.05 and lactating female rats (P < 0.01, with no significant effect on Oprm1 or Oprd1 gene activity. Thus, the expression of kappa-opioid receptors in the PAG may be modulated by single opioid receptor stimulation and behavioral meaningful opioidergic transmission in the adult female might occur simultaneously to specific changes in gene expression of kappa-opioid receptor subtype. This is yet another alert for the complex role of the opioid system in

  13. Activation of the GABAB receptor prevents nicotine-induced locomotor stimulation in mice

    Directory of Open Access Journals (Sweden)

    Carla eLobina

    2011-12-01

    Full Text Available Recent studies demonstrated that activation of the GABAB receptor, either by means of orthosteric agonists or positive allosteric modulators (PAMs, inhibited different nicotine-related behaviors, including intravenous self-administration and conditioned place preference, in rodents. The present study investigated whether the anti-nicotine effects of the GABAB receptor agonist, baclofen, and GABAB PAMs, CGP7930 and GS39783, extend to nicotine stimulant effects. To this end, CD1 mice were initially treated with baclofen (0, 1.25, and 2.5 mg/kg, i.p., CGP7930 (0, 25, and 50 mg/kg, i.g., or GS39783 (0, 25, and 50 mg/kg, i.g., then treated with nicotine (0 and 0.05 mg/kg, s.c., and finally exposed to an automated apparatus for recording of locomotor activity. Pretreatment with doses of baclofen, CGP7930, or GS39783 that did not alter locomotor activity when given with nicotine vehicle fully prevented hyperlocomotion induced by 0.05 mg/kg nicotine. These data extend to nicotine stimulant effects the capacity of baclofen and GABAB PAMs to block the reinforcing, motivational, and rewarding properties of nicotine. These data strengthen the hypothesis that activation of the GABAB receptor may represent a potentially useful, anti-smoking therapeutic strategy.

  14. Stimulation of cannabinoid receptor 2 (CB2 suppresses microglial activation

    Directory of Open Access Journals (Sweden)

    Fernandez Francisco

    2005-12-01

    Full Text Available Abstract Background Activated microglial cells have been implicated in a number of neurodegenerative disorders, including Alzheimer's disease (AD, multiple sclerosis (MS, and HIV dementia. It is well known that inflammatory mediators such as nitric oxide (NO, cytokines, and chemokines play an important role in microglial cell-associated neuron cell damage. Our previous studies have shown that CD40 signaling is involved in pathological activation of microglial cells. Many data reveal that cannabinoids mediate suppression of inflammation in vitro and in vivo through stimulation of cannabinoid receptor 2 (CB2. Methods In this study, we investigated the effects of a cannabinoid agonist on CD40 expression and function by cultured microglial cells activated by IFN-γ using RT-PCR, Western immunoblotting, flow cytometry, and anti-CB2 small interfering RNA (siRNA analyses. Furthermore, we examined if the stimulation of CB2 could modulate the capacity of microglial cells to phagocytise Aβ1–42 peptide using a phagocytosis assay. Results We found that the selective stimulation of cannabinoid receptor CB2 by JWH-015 suppressed IFN-γ-induced CD40 expression. In addition, this CB2 agonist markedly inhibited IFN-γ-induced phosphorylation of JAK/STAT1. Further, this stimulation was also able to suppress microglial TNF-α and nitric oxide production induced either by IFN-γ or Aβ peptide challenge in the presence of CD40 ligation. Finally, we showed that CB2 activation by JWH-015 markedly attenuated CD40-mediated inhibition of microglial phagocytosis of Aβ1–42 peptide. Taken together, these results provide mechanistic insight into beneficial effects provided by cannabinoid receptor CB2 modulation in neurodegenerative diseases, particularly AD.

  15. UV ACTIVATION OF RECEPTOR TYROSINE KINASE-ACTIVITY

    NARCIS (Netherlands)

    COFFER, PJ; BURGERING, BMT; PEPPELENBOSCH, MP; BOS, JL; KRUIJER, W

    1995-01-01

    The exposure of mammalian cells to ultraviolet radiation (UV) may lead to DNA damage resulting in mutation and thus possibly cancer, while irradiation can further act as a potent tumour promoter. In addition UV induces p21ras-mediated signalling leading to activation of transcription factors such as

  16. δ-Opioid receptor-stimulated Akt signaling in neuroblastoma x glioma (NG108-15) hybrid cells involves receptor tyrosine kinase-mediated PI3K activation

    International Nuclear Information System (INIS)

    Heiss, Anika; Ammer, Hermann; Eisinger, Daniela A.

    2009-01-01

    δ-Opioid receptor (DOR) agonists possess cytoprotective properties, an effect associated with activation of the 'pro-survival' kinase Akt. Here we delineate the signal transduction pathway by which opioids induce Akt activation in neuroblastoma x glioma (NG108-15) hybrid cells. Exposure of the cells to both [D-Pen 2,5 ]enkephalin and etorphine resulted in a time- and dose-dependent increase in Akt activity, as measured by means of an activation-specific antibody recognizing phosphoserine-473. DOR-mediated Akt signaling is blocked by the opioid antagonist naloxone and involves inhibitory G i/o proteins, because pre-treatment with pertussis toxin, but not over-expression of the G q/11 scavengers EBP50 and GRK2-K220R, prevented this effect. Further studies with Wortmannin and LY294002 revealed that phophoinositol-3-kinase (PI3K) plays a central role in opioid-induced Akt activation. Opioids stimulate Akt activity through transactivation of receptor tyrosine kinases (RTK), because pre-treatment of the cells with inhibitors for neurotrophin receptor tyrosine kinases (AG879) and the insulin-like growth factor receptor IGF-1 (AG1024), but not over-expression of the Gβγ scavenger phosducin, abolished this effect. Activated Akt translocates to the nuclear membrane, where it promotes GSK3 phosphorylation and prevents caspase-3 cleavage, two key events mediating inhibition of cell apoptosis and enhancement of cell survival. Taken together, these results demonstrate that in NG108-15 hybrid cells DOR agonists possess cytoprotective properties mediated by activation of the RTK/PI3K/Akt signaling pathway.

  17. {delta}-Opioid receptor-stimulated Akt signaling in neuroblastoma x glioma (NG108-15) hybrid cells involves receptor tyrosine kinase-mediated PI3K activation

    Energy Technology Data Exchange (ETDEWEB)

    Heiss, Anika; Ammer, Hermann [Institute of Pharmacology, Toxicology and Pharmacy Ludwig-Maximilians-University of Munich Koeniginstrasse 16 80539 Muenchen Federal Republic of Germany (Germany); Eisinger, Daniela A., E-mail: eisinger@pharmtox.vetmed.uni-muenchen.de [Institute of Pharmacology, Toxicology and Pharmacy Ludwig-Maximilians-University of Munich Koeniginstrasse 16 80539 Muenchen Federal Republic of Germany (Germany)

    2009-07-15

    {delta}-Opioid receptor (DOR) agonists possess cytoprotective properties, an effect associated with activation of the 'pro-survival' kinase Akt. Here we delineate the signal transduction pathway by which opioids induce Akt activation in neuroblastoma x glioma (NG108-15) hybrid cells. Exposure of the cells to both [D-Pen{sup 2,5}]enkephalin and etorphine resulted in a time- and dose-dependent increase in Akt activity, as measured by means of an activation-specific antibody recognizing phosphoserine-473. DOR-mediated Akt signaling is blocked by the opioid antagonist naloxone and involves inhibitory G{sub i/o} proteins, because pre-treatment with pertussis toxin, but not over-expression of the G{sub q/11} scavengers EBP50 and GRK2-K220R, prevented this effect. Further studies with Wortmannin and LY294002 revealed that phophoinositol-3-kinase (PI3K) plays a central role in opioid-induced Akt activation. Opioids stimulate Akt activity through transactivation of receptor tyrosine kinases (RTK), because pre-treatment of the cells with inhibitors for neurotrophin receptor tyrosine kinases (AG879) and the insulin-like growth factor receptor IGF-1 (AG1024), but not over-expression of the G{beta}{gamma} scavenger phosducin, abolished this effect. Activated Akt translocates to the nuclear membrane, where it promotes GSK3 phosphorylation and prevents caspase-3 cleavage, two key events mediating inhibition of cell apoptosis and enhancement of cell survival. Taken together, these results demonstrate that in NG108-15 hybrid cells DOR agonists possess cytoprotective properties mediated by activation of the RTK/PI3K/Akt signaling pathway.

  18. Facilitation of neocortical presynaptic terminal development by NMDA receptor activation

    Directory of Open Access Journals (Sweden)

    Sceniak Michael P

    2012-02-01

    Full Text Available Abstract Background Neocortical circuits are established through the formation of synapses between cortical neurons, but the molecular mechanisms of synapse formation are only beginning to be understood. The mechanisms that control synaptic vesicle (SV and active zone (AZ protein assembly at developing presynaptic terminals have not yet been defined. Similarly, the role of glutamate receptor activation in control of presynaptic development remains unclear. Results Here, we use confocal imaging to demonstrate that NMDA receptor (NMDAR activation regulates accumulation of multiple SV and AZ proteins at nascent presynaptic terminals of visual cortical neurons. NMDAR-dependent regulation of presynaptic assembly occurs even at synapses that lack postsynaptic NMDARs. We also provide evidence that this control of presynaptic terminal development is independent of glia. Conclusions Based on these data, we propose a novel NMDAR-dependent mechanism for control of presynaptic terminal development in excitatory neocortical neurons. Control of presynaptic development by NMDARs could ultimately contribute to activity-dependent development of cortical receptive fields.

  19. Forster Resonance Energy Transfer (FRET) Analysis of Dual CFP/YFP Labeled AMPA Receptors Reveals Structural Rearrangement within the C-Terminal Domain during Receptor Activation

    DEFF Research Database (Denmark)

    Zachariassen, Linda Grønborg; Katchan, Mila; Plested, Andrew

    2014-01-01

    that retain function and display intrareceptor FRET. This includes a construct (GluA2-6Y-10C) containing YFP in the intracellular loop between the M1 and M2 membrane-embedded segments and CFP inserted in the C-ter- minal domain (CTD). GluA2-6Y-10C displays FRET with an efficiency of 0.11 while retaining wild......-type receptor expression and kinetic properties. We have used GluA2-6Y-10C to study conformational changes in homomeric GluA2 receptors during receptor activation. Our results show that the FRET efficiency is dependent on functional state of GluA2-6Y-10C and hereby indi- cates that the intracellular CTD...

  20. Analysis of fluorescently labeled substance P analogs: binding, imaging and receptor activation

    Directory of Open Access Journals (Sweden)

    Simmons Mark A

    2001-06-01

    Full Text Available Abstract Background Substance P (SP is a peptide neurotransmitter found in central and peripheral nerves. SP is involved in the control of smooth muscle, inflammation and nociception. The amino acid sequence of SP is Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2. Five different forms of fluorescently labeled SP have recently been synthesized, in which Alexa 488, BODIPY Fl, fluorescein, Oregon Green 488 or tetramethylrhodamine has been covalently linked to SP at Lys3. Here, these novel analogs are characterized as to their ligand binding, receptor activation and fluorescence labeling properties. Results Competition binding studies, using radiolabeled [125I] SP, revealed that all of the labeled forms of SP, except for Alexa 488-SP, effectively competed with radiolabeled SP for binding at the rat SP receptor. With the exception of Alexa 488-SP, all of the SP analogs produced Ca++ elevations and fluorescence labeling of the SP receptor expressed in Chinese hamster ovary cells. In SP-responsive neurons, BODIPY Fl-SP and Oregon Green 488-SP were as effective as unlabeled SP in producing a reduction of the M-type K+ current. Fluorescein-SP produced variable results, while tetramethylrhodamine-SP was less potent and Alexa 488-SP was less effective on intact neurons. Conclusions The above results show that fluorescent labeling of SP altered the biological activity and the binding properties of the parent peptide. Oregon Green 488 and BODIPY FL-SP are the most useful fluorophores for labeling SP without affecting its biological activity. Given these results, these probes can now be utilized in further investigations of the mechanisms of SPR function, including receptor localization, internalization and recycling.

  1. Cross-talk between an activator of nuclear receptors-mediated transcription and the D1 dopamine receptor signaling pathway.

    Science.gov (United States)

    Schmidt, Azriel; Vogel, Robert; Rutledge, Su Jane; Opas, Evan E; Rodan, Gideon A; Friedman, Eitan

    2005-03-01

    Nuclear receptors are transcription factors that usually interact, in a ligand-dependent manner, with specific DNA sequences located within promoters of target genes. The nuclear receptors can also be controlled in a ligand-independent manner via the action of membrane receptors and cellular signaling pathways. 5-Tetradecyloxy-2-furancarboxylic acid (TOFA) was shown to stimulate transcription from the MMTV promoter via chimeric receptors that consist of the DNA binding domain of GR and the ligand binding regions of the PPARbeta or LXRbeta nuclear receptors (GR/PPARbeta and GR/LXRbeta). TOFA and hydroxycholesterols also modulate transcription from NF-kappaB- and AP-1-controlled reporter genes and induce neurite differentiation in PC12 cells. In CV-1 cells that express D(1) dopamine receptors, D(1) dopamine receptor stimulation was found to inhibit TOFA-stimulated transcription from the MMTV promoter that is under the control of chimeric GR/PPARbeta and GR/LXRbeta receptors. Treatment with the D(1) dopamine receptor antagonist, SCH23390, prevented dopamine-mediated suppression of transcription, and by itself increased transcription controlled by GR/LXRbeta. Furthermore, combined treatment of CV-1 cells with TOFA and SCH23390 increased transcription controlled by the GR/LXRbeta chimeric receptor synergistically. The significance of this in vitro synergy was demonstrated in vivo, by the observation that SCH23390 (but not haloperidol)-mediated catalepsy in rats was potentiated by TOFA, thus showing that an agent that mimics the in vitro activities of compounds that activate members of the LXR and PPAR receptor families can influence D1 dopamine receptor elicited responses.

  2. DESENSITIZATION PROPERTIES OF P2X3 RECEPTORS SHAPING PAIN SIGNALLING

    Directory of Open Access Journals (Sweden)

    Rashid eGiniatullin

    2013-12-01

    Full Text Available ATP-gated P2X3 receptors are mostly expressed by nociceptive sensory neurons and participate in transduction of pain signals. P2X3 receptors show a combination of fast desensitization onset and slow recovery. Moreover, even low nanomolar agonist concentrations unable to evoke a response, can induce desensitization via a phenomenon called ‘high affinity desensitization’. We have also observed that recovery from desensitization is agonist-specific and can range from seconds to minutes. The recovery process displays unusually high temperature dependence. Likewise, recycling of P2X3 receptors in peri-membrane regions shows unexpectedly large temperature sensitivity. By applying kinetic modeling, we have previously shown that desensitization characteristics of P2X3 receptor are best explained with a cyclic model of receptor operation involving three agonist molecules binding a single receptor and that desensitization is primarily developing from the open receptor state. Mutagenesis experiments suggested that desensitization depends on a certain conformation of the ATP binding pocket and on the structure of the transmembrane domains forming the ion pore. Further molecular determinants of desensitization have been identified by mutating the intracellular N- and C-termini of P2X3 receptor. Unlike other P2X receptors, the P2X3 subtype is facilitated by extracellular calcium that acts via specific sites in the ectodomain neighboring the ATP binding pocket. Thus, substitution of serine275 in this region (called ‘left flipper’ converts the natural facilitation induced by extracellular calcium to receptor inhibition. Given such their strategic location in nociceptive neurons and unique desensitization properties, P2X3 receptors represent an attractive target for development of new analgesic drugs via promotion of desensitization aimed at suppressing chronic pain.

  3. DMPD: Receptor tyrosine kinases and the regulation of macrophage activation. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 14726496 Receptor tyrosine kinases and the regulation of macrophage activation. Cor...osine kinases and the regulation of macrophage activation. PubmedID 14726496 Title Receptor tyrosine...rell PH, Morrison AC, Lutz MA. J Leukoc Biol. 2004 May;75(5):731-7. Epub 2004 Jan 14. (.png) (.svg) (.html) (.csml) Show Receptor tyr

  4. Dopamine receptor activation increases HIV entry into primary human macrophages.

    Directory of Open Access Journals (Sweden)

    Peter J Gaskill

    Full Text Available Macrophages are the primary cell type infected with HIV in the central nervous system, and infection of these cells is a major component in the development of neuropathogenesis and HIV-associated neurocognitive disorders. Within the brains of drug abusers, macrophages are exposed to increased levels of dopamine, a neurotransmitter that mediates the addictive and reinforcing effects of drugs of abuse such as cocaine and methamphetamine. In this study we examined the effects of dopamine on HIV entry into primary human macrophages. Exposure to dopamine during infection increased the entry of R5 tropic HIV into macrophages, irrespective of the concentration of the viral inoculum. The entry pathway affected was CCR5 dependent, as antagonizing CCR5 with the small molecule inhibitor TAK779 completely blocked entry. The effect was dose-dependent and had a steep threshold, only occurring above 108 M dopamine. The dopamine-mediated increase in entry required dopamine receptor activation, as it was abrogated by the pan-dopamine receptor antagonist flupenthixol, and could be mediated through both subtypes of dopamine receptors. These findings indicate that the effects of dopamine on macrophages may have a significant impact on HIV pathogenesis. They also suggest that drug-induced increases in CNS dopamine may be a common mechanism by which drugs of abuse with distinct modes of action exacerbate neuroinflammation and contribute to HIV-associated neurocognitive disorders in infected drug abusers.

  5. Synaptic activity regulates AMPA receptor trafficking through different recycling pathways

    Science.gov (United States)

    Zheng, Ning; Jeyifous, Okunola; Munro, Charlotte; Montgomery, Johanna M; Green, William N

    2015-01-01

    Changes in glutamatergic synaptic strength in brain are dependent on AMPA-type glutamate receptor (AMPAR) recycling, which is assumed to occur through a single local pathway. In this study, we present evidence that AMPAR recycling occurs through different pathways regulated by synaptic activity. Without synaptic stimulation, most AMPARs recycled in dynamin-independent endosomes containing the GTPase, Arf6. Few AMPARs recycled in dynamin-dependent endosomes labeled by transferrin receptors (TfRs). AMPAR recycling was blocked by alterations in the GTPase, TC10, which co-localized with Arf6 endosomes. TC10 mutants that reduced AMPAR recycling had no effect on increased AMPAR levels with long-term potentiation (LTP) and little effect on decreased AMPAR levels with long-term depression. However, internalized AMPAR levels in TfR-containing recycling endosomes increased after LTP, indicating increased AMPAR recycling through the dynamin-dependent pathway with synaptic plasticity. LTP-induced AMPAR endocytosis is inconsistent with local recycling as a source of increased surface receptors, suggesting AMPARs are trafficked from other sites. DOI: http://dx.doi.org/10.7554/eLife.06878.001 PMID:25970033

  6. Dopamine Receptor Activation Increases HIV Entry into Primary Human Macrophages

    Science.gov (United States)

    Gaskill, Peter J.; Yano, Hideaki H.; Kalpana, Ganjam V.; Javitch, Jonathan A.; Berman, Joan W.

    2014-01-01

    Macrophages are the primary cell type infected with HIV in the central nervous system, and infection of these cells is a major component in the development of neuropathogenesis and HIV-associated neurocognitive disorders. Within the brains of drug abusers, macrophages are exposed to increased levels of dopamine, a neurotransmitter that mediates the addictive and reinforcing effects of drugs of abuse such as cocaine and methamphetamine. In this study we examined the effects of dopamine on HIV entry into primary human macrophages. Exposure to dopamine during infection increased the entry of R5 tropic HIV into macrophages, irrespective of the concentration of the viral inoculum. The entry pathway affected was CCR5 dependent, as antagonizing CCR5 with the small molecule inhibitor TAK779 completely blocked entry. The effect was dose-dependent and had a steep threshold, only occurring above 108 M dopamine. The dopamine-mediated increase in entry required dopamine receptor activation, as it was abrogated by the pan-dopamine receptor antagonist flupenthixol, and could be mediated through both subtypes of dopamine receptors. These findings indicate that the effects of dopamine on macrophages may have a significant impact on HIV pathogenesis. They also suggest that drug-induced increases in CNS dopamine may be a common mechanism by which drugs of abuse with distinct modes of action exacerbate neuroinflammation and contribute to HIV-associated neurocognitive disorders in infected drug abusers. PMID:25268786

  7. Targeting protease activated receptor-1 with P1pal-12 limits bleomycin-induced pulmonary fibrosis

    NARCIS (Netherlands)

    Lin, Cong; Duitman, Janwillem; Daalhuisen, Joost; ten Brink, Marieke; von der Thüsen, Jan; van der Poll, Tom; Borensztajn, Keren; Spek, C. Arnold

    2014-01-01

    Idiopathic pulmonary fibrosis is the most devastating fibrotic diffuse parenchymal lung disease which remains refractory to pharmacological therapies. Therefore, novel treatments are urgently required. Protease-activated receptor (PAR)-1 is a G-protein-coupled receptor that mediates critical

  8. Antinociceptive Action of Isolated Mitragynine from Mitragyna Speciosa through Activation of Opioid Receptor System

    Directory of Open Access Journals (Sweden)

    Mohamad Aris Mohd Moklas

    2012-09-01

    Full Text Available Cannabinoids and opioids systems share numerous pharmacological properties and antinociception is one of them. Previous findings have shown that mitragynine (MG, a major indole alkaloid found in Mitragyna speciosa (MS can exert its antinociceptive effects through the opioids system. In the present study, the action of MG was investigated as the antinociceptive agent acting on Cannabinoid receptor type 1 (CB1 and effects on the opioids receptor. The latency time was recorded until the mice showed pain responses such as shaking, licking or jumping and the duration of latency was measured for 2 h at every 15 min interval by hot plate analysis. To investigate the beneficial effects of MG as antinociceptive agent, it was administered intraperitoneally 15 min prior to pain induction with a single dosage (3, 10, 15, 30, and 35 mg/kg b.wt. In this investigation, 35 mg/kg of MG showed significant increase in the latency time and this dosage was used in the antagonist receptor study. The treated groups were administered with AM251 (cannabinoid receptor-1 antagonist, naloxone (non-selective opioid antagonist, naltrindole (δ-opioid antagonist naloxonazine (µ1-receptor antagonist and norbinaltorpimine (κ-opioid antagonist respectively, prior to administration of MG (35 mg/kg. The results showed that the antinociceptive effect of MG was not antagonized by AM251; naloxone and naltrindole were effectively blocked; and norbinaltorpimine partially blocked the antinociceptive effect of MG. Naloxonazine did inhibit the effect of MG, but it was not statistically significant. These results demonstrate that CB1 does not directly have a role in the antinociceptive action of MG where the effect was observed with the activation of opioid receptor.

  9. Functionally Selective AT(1) Receptor Activation Reduces Ischemia Reperfusion Injury

    DEFF Research Database (Denmark)

    Hostrup, Anders; Christensen, Gitte Lund; Bentzen, Bo Hjort

    2012-01-01

    of the physiological functions of AngII. The AT(1)R mediates its effects through both G protein-dependent and independent signaling, which can be separated by functionally selective agonists. In the present study we investigate the effect of AngII and the ß-arrestin biased agonist [SII]AngII on ischemia......]AngII had a protective effect. Together these results demonstrate a cardioprotective effect of simultaneous blockade of G protein signaling and activation of G protein independent signaling through AT(1 )receptors....

  10. Vitamin D receptor activation and survival in chronic kidney disease.

    Science.gov (United States)

    Kovesdy, C P; Kalantar-Zadeh, K

    2008-06-01

    Replacement of activated vitamin D has been the cornerstone of therapy for secondary hyperparathyroidism (SHPT). Recent findings from several large observational studies have suggested that the benefits of vitamin D receptor activators (VDRA) may extend beyond the traditional parathyroid hormone (PTH)-lowering effect, and could result in direct cardiovascular and metabolic benefits. The advent of several new analogs of the activated vitamin D molecule has widened our therapeutic armamentarium, but has also made therapeutic decisions more complicated. Treatment of SHPT has become even more complex with the arrival of the first calcium-sensing receptor (CSR) agonist (cinacalcet hydrochloride) and with the uncovering of novel mechanisms responsible for SHPT. We provide a brief overview of the physiology and pathophysiology of SHPT, with a focus on vitamin D metabolism, and discuss various practical aspects of VDRA therapy and its reported association with survival in recent observational studies. A detailed discussion of the available agents is aimed at providing the practicing physician with a clear understanding of the advantages or disadvantages of the individual medications. A number of open questions are also analyzed, including the present and future roles of CSR agonists and 25(OH) vitamin D replacement.

  11. Quantitative properties and receptor reserve of the IP(3) and calcium branch of G(q)-coupled receptor signaling.

    Science.gov (United States)

    Dickson, Eamonn J; Falkenburger, Björn H; Hille, Bertil

    2013-05-01

    Gq-coupled plasma membrane receptors activate phospholipase C (PLC), which hydrolyzes membrane phosphatidylinositol 4,5-bisphosphate (PIP2) into the second messengers inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). This leads to calcium release, protein kinase C (PKC) activation, and sometimes PIP2 depletion. To understand mechanisms governing these diverging signals and to determine which of these signals is responsible for the inhibition of KCNQ2/3 (KV7.2/7.3) potassium channels, we monitored levels of PIP2, IP3, and calcium in single living cells. DAG and PKC are monitored in our companion paper (Falkenburger et al. 2013. J. Gen. Physiol. http://dx.doi.org/10.1085/jgp.201210887). The results extend our previous kinetic model of Gq-coupled receptor signaling to IP3 and calcium. We find that activation of low-abundance endogenous P2Y2 receptors by a saturating concentration of uridine 5'-triphosphate (UTP; 100 µM) leads to calcium release but not to PIP2 depletion. Activation of overexpressed M1 muscarinic receptors by 10 µM Oxo-M leads to a similar calcium release but also depletes PIP2. KCNQ2/3 channels are inhibited by Oxo-M (by 85%), but not by UTP (calcium responses can be elicited even after PIP2 was partially depleted by overexpressed inducible phosphatidylinositol 5-phosphatases, suggesting that very low amounts of IP3 suffice to elicit a full calcium release. Hence, weak PLC activation can elicit robust calcium signals without net PIP2 depletion or KCNQ2/3 channel inhibition.

  12. Structure-activity relationships for serotonin transporter and dopamine receptor selectivity.

    Science.gov (United States)

    Agatonovic-Kustrin, Snezana; Davies, Paul; Turner, Joseph V

    2009-05-01

    Antipsychotic medications have a diverse pharmacology with affinity for serotonergic, dopaminergic, adrenergic, histaminergic and cholinergic receptors. Their clinical use now also includes the treatment of mood disorders, thought to be mediated by serotonergic receptor activity. The aim of our study was to characterise the molecular properties of antipsychotic agents, and to develop a model that would indicate molecular specificity for the dopamine (D(2)) receptor and the serotonin (5-HT) transporter. Back-propagation artificial neural networks (ANNs) were trained on a dataset of 47 ligands categorically assigned antidepressant or antipsychotic utility. The structure of each compound was encoded with 63 calculated molecular descriptors. ANN parameters including hidden neurons and input descriptors were optimised based on sensitivity analyses, with optimum models containing between four and 14 descriptors. Predicted binding preferences were in excellent agreement with clinical antipsychotic or antidepressant utility. Validated models were further tested by use of an external prediction set of five drugs with unknown mechanism of action. The SAR models developed revealed the importance of simple molecular characteristics for differential binding to the D(2) receptor and the 5-HT transporter. These included molecular size and shape, solubility parameters, hydrogen donating potential, electrostatic parameters, stereochemistry and presence of nitrogen. The developed models and techniques employed are expected to be useful in the rational design of future therapeutic agents.

  13. The pharmacology of TD-8954, a potent and selective 5-HT4 receptor agonist with gastrointestinal prokinetic properties

    Directory of Open Access Journals (Sweden)

    David T Beattie

    2011-05-01

    Full Text Available This study evaluated the in vitro and in vivo pharmacological properties of TD-8954, a potent and selective 5-HT4 receptor agonist. TD-8954 had high affinity (pKi = 9.4 for human recombinant 5-HT4(c (h5-HT4(c receptors, and selectivity (> 2,000-fold over all other 5-HT receptors and non-5-HT receptors, ion channels, enzymes and transporters tested (n = 78. TD-8954 produced an elevation of cAMP in HEK-293 cells expressing the h5-HT4(c receptor (pEC50 = 9.3, and contracted the guinea pig colonic longitudinal muscle/myenteric plexus (LMMP preparation (pEC50 = 8.6. TD-8954 had moderate intrinsic activity (IA in the in vitro assays. In conscious guinea pigs, subcutaneous (s.c. administration of TD 8954 (0.03 - 3 mg/kg increased the colonic transit of carmine red dye, reducing the time taken for its excretion. Following intraduodenal (i.d. dosing to anesthetized rats, TD 8954 (0.03 - 10 mg/kg evoked a dose-dependent relaxation of the esophagus. Following oral administration to conscious dogs, TD 8954 (10 and 30 µg/kg produced an increase in contractility of the antrum, duodenum and jejunum. In a single ascending oral dose study in healthy human subjects, TD-8954 (0.1 - 20 mg increased bowel movement frequency and reduced the time to first stool. It is concluded that TD-8954 is a potent and selective 5-HT4 receptor agonist in vitro, with robust in vivo stimulatory activity in the gastrointestinal (GI tract of guinea pigs, rats, dogs and humans. TD-8954 may have clinical utility in patients with disorders of reduced GI motility.

  14. Morphological and photometric properties of active and non-active ...

    African Journals Online (AJOL)

    Context: The differences in properties of active and non-active galaxies in the green valley have been studied in the quest of finding the driving mechanism behind the evolutionary transition from the blue cloud to the red sequence galaxies. Aims: Using COSMOS data, as one of the deepest surveys, and X-ray detected ...

  15. Isoliquiritigenin exhibits anti-proliferative properties in the pituitary independent of estrogen receptor function

    International Nuclear Information System (INIS)

    Weis, Karen E.; Raetzman, Lori T.

    2016-01-01

    The plant flavonoid isoliquiritigenin (ISL) is a botanical estrogen widely taken as an herbal supplement to ease the symptoms of menopause. ISL has been also shown to have anti-tumor properties in a number of cancer cell backgrounds. However, the effects of ISL on normal cells are less well known and virtually unstudied in the context of the pituitary gland. We have established a pituitary explant culture model to screen chemical agents for gene expression changes within the pituitary gland during a period of active proliferation and differentiation. Using this whole-organ culture system we found ISL to be weakly estrogenic based on its ability to induce Cckar mRNA expression, an estrogen receptor (ER) mediated gene. Using a range of ISL from 200 nM to 200 μM, we discovered that ISL promoted cell proliferation at a low concentration, yet potently inhibited proliferation at the highest concentration. ICI 182,780 failed to antagonize ISL's repression of pituitary cell proliferation, indicating the effect is independent of ER signaling. Coincident with a decrease in proliferating cells, we observed down-regulation of transcript for cyclin D2 and E2 and a strong induction of mRNA and protein for the cyclin dependent kinase inhibitor Cdkn1a (p21). Importantly, high dose ISL did not alter the balance of progenitor vs. differentiated cell types within the pituitary explants and they seemed otherwise healthy; however, TUNEL staining revealed an increase in apoptotic cell death in ISL treated cultures. Our results merit further examination of ISL as an anti-tumor agent in the pituitary gland. - Highlights: • Isoliquiritigenin possesses weak estrogenic activity based on induction of Cckar. • ISL can be anti-proliferative in pituitary explants without altering cell lineages. • Anti-proliferative behavior of ISL is not estrogen receptor mediated. • ISL induces p21 expression leading to cell cycle arrest and apoptosis.

  16. Isoliquiritigenin exhibits anti-proliferative properties in the pituitary independent of estrogen receptor function

    Energy Technology Data Exchange (ETDEWEB)

    Weis, Karen E.; Raetzman, Lori T., E-mail: raetzman@life.illinois.edu

    2016-12-15

    The plant flavonoid isoliquiritigenin (ISL) is a botanical estrogen widely taken as an herbal supplement to ease the symptoms of menopause. ISL has been also shown to have anti-tumor properties in a number of cancer cell backgrounds. However, the effects of ISL on normal cells are less well known and virtually unstudied in the context of the pituitary gland. We have established a pituitary explant culture model to screen chemical agents for gene expression changes within the pituitary gland during a period of active proliferation and differentiation. Using this whole-organ culture system we found ISL to be weakly estrogenic based on its ability to induce Cckar mRNA expression, an estrogen receptor (ER) mediated gene. Using a range of ISL from 200 nM to 200 μM, we discovered that ISL promoted cell proliferation at a low concentration, yet potently inhibited proliferation at the highest concentration. ICI 182,780 failed to antagonize ISL's repression of pituitary cell proliferation, indicating the effect is independent of ER signaling. Coincident with a decrease in proliferating cells, we observed down-regulation of transcript for cyclin D2 and E2 and a strong induction of mRNA and protein for the cyclin dependent kinase inhibitor Cdkn1a (p21). Importantly, high dose ISL did not alter the balance of progenitor vs. differentiated cell types within the pituitary explants and they seemed otherwise healthy; however, TUNEL staining revealed an increase in apoptotic cell death in ISL treated cultures. Our results merit further examination of ISL as an anti-tumor agent in the pituitary gland. - Highlights: • Isoliquiritigenin possesses weak estrogenic activity based on induction of Cckar. • ISL can be anti-proliferative in pituitary explants without altering cell lineages. • Anti-proliferative behavior of ISL is not estrogen receptor mediated. • ISL induces p21 expression leading to cell cycle arrest and apoptosis.

  17. Involvement of Activating NK Cell Receptors and Their Modulation in Pathogen Immunity

    Directory of Open Access Journals (Sweden)

    Francesco Marras

    2011-01-01

    Full Text Available Natural Killer (NK cells are endowed with cell-structure-sensing receptors providing inhibitory protection from self-destruction (inhibitory NK receptors, iNKRs, including killer inhibitory receptors and other molecules and rapid triggering potential leading to functional cell activation by Toll-like receptors (TLRs, cytokine receptors, and activating NK cell receptors including natural cytotoxicity receptors (NCRs, i.e., NKp46, NKp46, and NKp44. NCR and NKG2D recognize ligands on infected cells which may be endogenous or may directly bind to some structures derived from invading pathogens. In this paper, we address the known direct or indirect interactions between activating receptors and pathogens and their expression during chronic HIV and HCV infections.

  18. An improved ivermectin-activated chloride channel receptor for inhibiting electrical activity in defined neuronal populations

    DEFF Research Database (Denmark)

    Lynagh, Timothy Peter; Lynch, Joseph W

    2010-01-01

    The ability to silence the electrical activity of defined neuronal populations in vivo is dramatically advancing our understanding of brain function. This technology may eventually be useful clinically for treating a variety of neuropathological disorders caused by excessive neuronal activity...... conductance, homomeric expression, and human origin may render the F207A/A288G alpha1 glycine receptor an improved silencing receptor for neuroscientific and clinical purposes. As all known highly ivermectin-sensitive GluClRs contain an endogenous glycine residue at the corresponding location, this residue...

  19. Peroxisome Proliferators-Activated Receptor (PPAR Modulators and Metabolic Disorders

    Directory of Open Access Journals (Sweden)

    Min-Chul Cho

    2008-01-01

    Full Text Available Overweight and obesity lead to an increased risk for metabolic disorders such as impaired glucose regulation/insulin resistance, dyslipidemia, and hypertension. Several molecular drug targets with potential to prevent or treat metabolic disorders have been revealed. Interestingly, the activation of peroxisome proliferator-activated receptor (PPAR, which belongs to the nuclear receptor superfamily, has many beneficial clinical effects. PPAR directly modulates gene expression by binding to a specific ligand. All PPAR subtypes (α,γ, and σ are involved in glucose metabolism, lipid metabolism, and energy balance. PPAR agonists play an important role in therapeutic aspects of metabolic disorders. However, undesired effects of the existing PPAR agonists have been reported. A great deal of recent research has focused on the discovery of new PPAR modulators with more beneficial effects and more safety without producing undesired side effects. Herein, we briefly review the roles of PPAR in metabolic disorders, the effects of PPAR modulators in metabolic disorders, and the technologies with which to discover new PPAR modulators.

  20. Role of Peroxisome Proliferator-Activated Receptors in Inflammation Control

    Directory of Open Access Journals (Sweden)

    Jihan Youssef

    2004-01-01

    Full Text Available Peroxisome proliferator-activated receptors (PPARs were discovered over a decade ago, and were classified as orphan members of the nuclear receptor superfamily. To date, three PPAR subtypes have been discovered and characterized (PPARα, β/δ, γ. Different PPAR subtypes have been shown to play crucial roles in important diseases and conditions such as obesity, diabetes, atherosclerosis, cancer, and fertility. Among the most studied roles of PPARs is their involvement in inflammatory processes. Numerous studies have revealed that agonists of PPARα and PPARγ exert anti-inflammatory effects both in vitro and in vivo. Using the carrageenan-induced paw edema model of inflammation, a recent study in our laboratories showed that these agonists hinder the initiation phase, but not the late phase of the inflammatory process. Furthermore, in the same experimental model, we recently also observed that activation of PPARδ exerted an anti-inflammatory effect. Despite the fact that exclusive dependence of these effects on PPARs has been questioned, the bulk of evidence suggests that all three PPAR subtypes, PPARα,δ,γ, play a significant role in controlling inflammatory responses. Whether these subtypes act via a common mechanism or are independent of each other remains to be elucidated. However, due to the intensity of research efforts in this area, it is anticipated that these efforts will result in the development of PPAR ligands as therapeutic agents for the treatment of inflammatory diseases.

  1. Cyclic AMP-receptor protein activates aerobactin receptor IutA expression in Vibrio vulnificus.

    Science.gov (United States)

    Kim, Choon-Mee; Kim, Seong-Jung; Shin, Sung-Heui

    2012-04-01

    The ferrophilic bacterium Vibrio vulnificus can utilize the siderophore aerobactin of Escherichia coli for iron acquisition via its specific receptor IutA. This siderophore piracy by V. vulnificus may contribute to its survival and proliferation, especially in mixed bacterial environments. In this study, we examined the effects of glucose, cyclic AMP (cAMP), and cAMP-receptor protein (Crp) on iutA expression in V. vulnificus. Glucose dose-dependently repressed iutA expression. A mutation in cya encoding adenylate cyclase required for cAMP synthesis severely repressed iutA expression, and this change was recovered by in trans complementing cya or the addition of exogenous cAMP. Furthermore, a mutation in crp encoding Crp severely repressed iutA expression, and this change was recovered by complementing crp. Accordingly, glucose deprivation under iron-limited conditions is an environmental signal for iutA expression, and Crp functions as an activator that regulates iutA expression in response to glucose availability.

  2. Cyprodinil as an activator of aryl hydrocarbon receptor

    International Nuclear Information System (INIS)

    Fang, Chien-Chung; Chen, Fei-Yun; Chen, Chang-Rong; Liu, Chien-Chiang; Wong, Liang-Chi; Liu, Yi-Wen; Su, Jyan-Gwo Joseph

    2013-01-01

    Highlights: ► Cyprodinil activated the aryl hydrocarbon receptor (AHR). ► Cyprodinil induced nuclear translocation of the AHR, and the expression of CYP1A1. ► Cyprodinil enhanced dexamethasone-induced gene expression. ► Cyprodinil phosphorylated ERK, indicating its deregulation of ERK activity. -- Abstract: Cyprodinil is a pyrimidinamine fungicide, used worldwide by agriculture. It is used to protect fruit plants and vegetables from a wide range of pathogens. Benzo[a]pyrene (BaP) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are toxic environmental pollutants and are prototypes of aryl hydrocarbon receptor (AHR) ligands. Although the structure of cyprodinil distinctly differs from those of BaP and TCDD, our results show that cyprodinil induced nuclear translocation of the AHR, and induced the transcriptional activity of aryl hydrocarbon response element (AHRE). Cyprodinil induced the expression of cytochrome P450 (CYP) 1A1, a well-known AHR-targeted gene, in ovarian granulosa cells, HO23, and hepatoma cells, Hepa-1c1c7. Its induction did not appear in AHR signal-deficient cells, and was blocked by the AHR antagonist, CH-223191. Cyprodinil decreased AHR expression in HO23 cells, resulting in CYP1A1 expression decreasing after it peaked at 9 h of treatment in HO23 cells. Dexamethasone is a synthetic agonist of glucocorticoids. Cyprodinil enhanced dexamethasone-induced gene expression, and conversely, its induction of CYP1A1 expression was decreased by dexamethasone in HO23 cells, indicating its induction of crosstalk between the AHR and glucocorticoid receptor and its role as a potential endocrine disrupter. In addition to BaP, TCDD, and an AHR agonist, β-NF, cyprodinil also phosphorylated extracellular signal-regulated kinase (ERK) in HO23 and Hepa-1c1c7 cells, indicating its deregulation of ERK activity. In summary, our results demonstrate that cyprodinil, similar to BaP, acts as an AHR activator, a potential endocrine disrupter, and an ERK disrupter

  3. Activated protein C (APC) can increase bone anabolism via a protease-activated receptor (PAR)1/2 dependent mechanism.

    Science.gov (United States)

    Shen, Kaitlin; Murphy, Ciara M; Chan, Ben; Kolind, Mille; Cheng, Tegan L; Mikulec, Kathy; Peacock, Lauren; Xue, Meilang; Park, Sang-Youel; Little, David G; Jackson, Chris J; Schindeler, Aaron

    2014-12-01

    Activated Protein C (APC) is an anticoagulant with strong cytoprotective properties that has been shown to promote wound healing. In this study APC was investigated for its potential orthopedic application using a Bone Morphogenetic Protein 2 (rhBMP-2) induced ectopic bone formation model. Local co-administration of 10 µg rhBMP-2 with 10 µg or 25 µg APC increased bone volume at 3 weeks by 32% (N.S.) and 74% (pAPC are largely mediated by its receptors endothelial protein C receptor (EPCR) and protease-activated receptors (PARs). Cultured pre-osteoblasts and bone nodule tissue sections were shown to express PAR1/2 and EPCR. When pre-osteoblasts were treated with APC, cell viability and phosphorylation of ERK1/2, Akt, and p38 were increased. Inhibition with PAR1 and sometimes PAR2 antagonists, but not with EPCR blocking antibodies, ameliorated the effects of APC on cell viability and kinase phosphorylation. These data indicate that APC can affect osteoblast viability and signaling, and may have in vivo applications with rhBMP-2 for bone repair. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  4. Pregnanolone glutamate, a novel use-dependent NMDA receptor inhibitor, exerts antidepressant-like properties in animal models.

    Directory of Open Access Journals (Sweden)

    Karel eVales

    2014-04-01

    Full Text Available A number of studies demonstrated a rapid onset of an antidepressant effect of non-competitive NMDA receptor antagonists. Nonetheless, its therapeutic potential is rather limited, due to a high coincidence of negative side-effects. Therefore, the challenge seems to be in the development of NMDA receptor (NMDAR antagonists displaying antidepressant properties, and at the same time maintaining regular physiological function of the NMDAR. Previous results demonstrated that naturally occurring neurosteroid 3α5β-pregnanolone sulfate shows pronounced inhibitory action by a use-dependent mechanism on the tonically active NMDAR. The aim of the present experiments is to find out whether the treatment with pregnanolone 3αC derivatives affects behavioral response to chronic and acute stress in an animal model of depression. Adult male mice were used throughout the study. Repeated social defeat and forced swimming tests were used as animal models of depression. The effect of the drugs on the locomotor/exploratory activity in the open-field test was also tested together with an effect on anxiety in the elevated plus maze. Results showed that pregnanolone glutamate (PG did not induce hyperlocomotion, whereas both dizocilpine and ketamine significantly increased spontaneous locomotor activity in the open field. In the elevated plus maze PG displayed anxiolytic-like properties. In forced swimming PG prolonged time to the first floating. Acute treatment of PG disinhibited suppressed locomotor activity in the repeatedly defeated group-housed mice. Aggressive behavior of isolated mice was reduced after the chronic 30-day administration of PG. PG showed antidepressant-like and anxiolytic-like properties in the used tests, with minimal side-effects. Since PG combines GABAA receptor potentiation and use-dependent NMDAR inhibition, synthetic derivatives of neuroactive steroids present a promising strategy for the treatment of mood disorders.

  5. Regulation of platelet activating factor receptor coupled phosphoinositide-specific phospholipase C activity

    International Nuclear Information System (INIS)

    Morrison, W.J.

    1988-01-01

    The major objectives of this study were two-fold. The first was to establish whether binding of platelet activating factor (PAF) to its receptor was integral to the stimulation of polyphosphoinositide-specific phospholipase C (PLC) in rabbit platelets. The second was to determine regulatory features of this receptor-coupled mechanism. [ 3 H]PAF binding demonstrated two binding sites, a high affinity site with a inhibitory constant (Ki) of 2.65 nM and a low affinity site with a Ki of 0.80 μM. PAF receptor coupled activation of phosphoinositide-specific PLC was studied in platelets which were made refractory, by short term pretreatments, to either PAF or thrombin. Saponin-permeabilized rabbit platelets continue to regulate the mechanism(s) coupling PAF receptors to PLC stimulation. However, TRPγS and GDPβS, which affect guanine nucleotide regulatory protein functions, were unable to modulate the PLC activity to any appreciable extent as compared to PAF. The possible involvement of protein kinase C (PKC) activation in regulating PAF-stimulated PLC activity was studied in rabbit platelets pretreated with staurosporine followed by pretreatments with PAF or phorbol 12-myristate 13-acetate (PMA)

  6. The role of GH receptor tyrosine phosphorylation in Stat5 activation

    DEFF Research Database (Denmark)

    Hansen, J A; Hansen, L H; Wang, X

    1997-01-01

    Stimulation of GH receptors leads to rapid activation of Jak2 kinase and subsequent tyrosine phosphorylation of the GH receptor. Three specific tyrosines located in the C-terminal domain of the GH receptor have been identified as being involved in GH-stimulated transcription of the Spi 2.1 promoter....... Mutated GH receptors lacking all but one of these three tyrosines are able to mediate a transcriptional response when transiently transfected into CHO cells together with a Spi 2.1 promoter/luciferase construct. Similarly, these GH receptors were found to be able to mediate activation of Stat5 DNA......-binding activity, whereas the GH receptor mutant lacking all intracellular tyrosines was not. Synthetic tyrosine phosphorylated peptides corresponding to the GH receptor sequence around the three tyrosines inhibited Stat5 DNA-binding activity while their non-phosphorylated counterparts were ineffective. Tyrosine...

  7. Fc-receptor-mediated phagocytosis is regulated by mechanical properties of the target

    Science.gov (United States)

    Beningo, Karen A.; Wang, Yu-li

    2002-01-01

    Phagocytosis is an actin-based process used by macrophages to clear particles greater than 0.5 microm in diameter. In addition to its role in immunological responses, phagocytosis is also necessary for tissue remodeling and repair. To prevent catastrophic autoimmune reactions, phagocytosis must be tightly regulated. It is commonly assumed that the recognition/selection of phagocytic targets is based solely upon receptor-ligand binding. Here we report an important new criterion, that mechanical parameters of the target can dramatically affect the efficiency of phagocytosis. When presented with particles of identical chemical properties but different rigidity, macrophages showed a strong preference to engulf rigid objects. Furthermore, phagocytosis of soft particles can be stimulated with the microinjection of constitutively active Rac1 but not RhoA, and with lysophosphatidic acid, an agent known to activate the small GTP-binding proteins of the Rho family. These data suggest a Rac1-dependent mechanosensory mechanism for phagocytosis, which probably plays an important role in a number of physiological and pathological processes from embryonic development to autoimmune diseases.

  8. Antibody-induced dimerization activates the epidermal growth factor receptor tyrosine kinase

    NARCIS (Netherlands)

    Spaargaren, M.; Defize, L. H.; Boonstra, J.; de Laat, S. W.

    1991-01-01

    The relationship between epidermal growth factor receptor (EGF-R) protein tyrosine kinase activation and ligand-induced receptor dimerization was investigated using several bivalent anti-EGF-R antibodies directed against various receptor epitopes. In A431 membrane preparations and permeabilized

  9. Molecular pharmacological phenotyping of EBI2. An orphan seven-transmembrane receptor with constitutive activity

    DEFF Research Database (Denmark)

    Rosenkilde, Mette M; Benned-Jensen, Tau; Holst, Peter J

    2006-01-01

    Epstein-Barr virus (EBV)-induced receptor 2 (EBI2) is an orphan seven-transmembrane (7TM) receptor originally identified as the most up-regulated gene (>200-fold) in EBV-infected cells. Here we show that EBI2 signals with constitutive activity through Galpha(i) as determined by a receptor...

  10. Role of ELA region in auto-activation of mutant KIT receptor: a molecular dynamics simulation insight.

    Science.gov (United States)

    Purohit, Rituraj

    2014-01-01

    KIT receptor is the prime target in gastrointestinal stromal tumor (GISTs) therapy. Second generation inhibitor, Sunitinib, binds to an inactivated conformation of KIT receptor and stabilizes it in order to prevent tumor formation. Here, we investigated the dynamic behavior of wild type and mutant D816H KIT receptor, and emphasized the extended A-loop (EAL) region (805-850) by conducting molecular dynamics simulation (∼100 ns). We analyzed different properties such as root mean square cutoff or deviation, root mean square fluctuation, radius of gyration, solvent-accessible surface area, hydrogen bonding network analysis, and essential dynamics. Apart from this, clustering and cross-correlation matrix approach was used to explore the conformational space of the wild type and mutant EAL region of KIT receptor. Molecular dynamics analysis indicated that mutation (D816H) was able to alter intramolecular hydrogen bonding pattern and affected the structural flexibility of EAL region. Moreover, flexible secondary elements, specially, coil and turns were dominated in EAL region of mutant KIT receptor during simulation. This phenomenon increased the movement of EAL region which in turn helped in shifting the equilibrium towards the active kinase conformation. Our atomic investigation of mutant KIT receptor which emphasized on EAL region provided a better insight into the understanding of Sunitinib resistance mechanism of KIT receptor and would help to discover new therapeutics for KIT-based resistant tumor cells in GIST therapy.

  11. Peroxisome Proliferator-Activated Receptor-γ in Thyroid Autoimmunity

    Directory of Open Access Journals (Sweden)

    Silvia Martina Ferrari

    2015-01-01

    Full Text Available Peroxisome proliferator-activated receptor- (PPAR- γ expression has been shown in thyroid tissue from patients with thyroiditis or Graves’ disease and furthermore in the orbital tissue of patients with Graves’ ophthalmopathy (GO, such as in extraocular muscle cells. An increasing body of evidence shows the importance of the (C-X-C motif receptor 3 (CXCR3 and cognate chemokines (C-X-C motif ligand (CXCL9, CXCL10, and CXCL11, in the T helper 1 immune response and in inflammatory diseases such as thyroid autoimmune disorders. PPAR-γ agonists show a strong inhibitory effect on the expression and release of CXCR3 chemokines, in vitro, in various kinds of cells, such as thyrocytes, and in orbital fibroblasts, preadipocytes, and myoblasts from patients with GO. Recently, it has been demonstrated that rosiglitazone is involved in a higher risk of heart failure, stroke, and all-cause mortality in old patients. On the contrary, pioglitazone has not shown these effects until now; this favors pioglitazone for a possible use in patients with thyroid autoimmunity. However, further studies are ongoing to explore the use of new PPAR-γ agonists in the treatment of thyroid autoimmune disorders.

  12. Topical Rosiglitazone Treatment Improves Ulcerative Colitis by Restoring Peroxisome Proliferator-Activated Receptor-gamma Activity

    DEFF Research Database (Denmark)

    Pedersen, G.; Brynskov, Jørn

    2010-01-01

    OBJECTIVES: Impaired epithelial expression of peroxisome proliferator-activated receptor-gamma (PPAR gamma) has been described in animal colitis models and briefly in patients with ulcerative colitis, but the functional significance in humans is not well defined. We examined PPAR gamma expression...

  13. Activation of Protease-Activated Receptor 2 Induces VEGF Independently of HIF-1

    DEFF Research Database (Denmark)

    Rasmussen, J.G.; Riis, Simone Elkjær; Frøbert, O.

    2012-01-01

    Human adipose stem cells (hASCs) can promote angiogenesis through secretion of proangiogenic factors such as vascular endothelial growth factor (VEGF). In other cell types, it has been shown that induction of VEGF is mediated by both protease activated receptor 2 (PAR2) and hypoxia inducible fact...

  14. Substance P receptor desensitization requires receptor activation but not phospholipase C

    International Nuclear Information System (INIS)

    Sugiya, Hiroshi; Putney, J.W. Jr.

    1988-01-01

    Previous studies have shown that exposure of parotid acinar cells to substance P at 37 degree C results in activation of phospholipase C, formation of [ 3 H]inositol 1,4,5-trisphosphate (IP 3 ), and persistent desensitization of the substance P response. In cells treated with antimycin in medium containing glucose, ATP was decreased to ∼20% of control values, IP 3 formation was completely inhibited, but desensitization was unaffected. When cells were treated with antimycin in the absence of glucose, cellular ATP was decreased to ∼5% of control values, and both IP 3 formation and desensitization were blocked. A series of substance P-related peptides increased the formation of [ 3 H]IP 3 and induced desensitization of the substance P response with a similar rank order of potencies. The substance P antagonist, [D-Pro 2 , D-Try 7,9 ]-substance P, inhibited substance P-induced IP 3 formation and desensitization but did not induce desensitization. These results suggest that the desensitization of substance P-induced IP 3 formation requires agonist activation of a P-type substance P receptor, and that one or more cellular ATP-dependent processes are required for this reaction. However, activation of phospholipase C and the generation of inositol phosphates does not seem to be a prerequisite for desensitization

  15. Recognition properties of receptors consisting of imidazole and indole recognition units towards carbohydrates

    Directory of Open Access Journals (Sweden)

    Monika Mazik

    2010-02-01

    Full Text Available Compounds 4 and 5, including both 4(5-substituted imidazole or 3-substituted indole units as the entities used in nature, and 2-aminopyridine group as a heterocyclic analogue of the asparagine/glutamine primary amide side chain, were prepared and their binding properties towards carbohydrates were studied. The design of these receptors was inspired by the binding motifs observed in the crystal structures of protein–carbohydrate complexes. 1H NMR spectroscopic titrations in competitive and non-competitive media as well as binding studies in two-phase systems, such as dissolution of solid carbohydrates in apolar media, revealed both highly effective recognition of neutral carbohydrates and interesting binding preferences of these acyclic compounds. Compared to the previously described acyclic receptors, compounds 4 and 5 showed significantly increased binding affinity towards β-galactoside. Both receptors display high β- vs. α-anomer binding preferences in the recognition of glycosides. It has been shown that both hydrogen bonding and interactions of the carbohydrate CH units with the aromatic rings of the receptors contribute to the stabilization of the receptor–carbohydrate complexes. The molecular modeling calculations, synthesis and binding properties of 4 and 5 towards selected carbohydrates are described and compared with those of the previously described receptors.

  16. Exercise reduces adipose tissue via cannabinoid receptor type 1 which is regulated by peroxisome proliferator-activated receptor-delta

    DEFF Research Database (Denmark)

    Yan, Zhen Cheng; Liu, Dao Yan; Zhang, Li Li

    2007-01-01

    Obesity is one major cardiovascular risk factor. We tested effects of endurance exercise on cannabinoid receptor type 1 (CB1) and peroxisome proliferator-activated receptor-delta (PPAR-delta)-dependent pathways in adipose tissue. Male Wistar rats were randomly assigned to standard laboratory chow...... or a high-fat diet without and with regular endurance exercise. Exercise in rats on high-fat diet significantly reduced visceral fat mass, blood pressure, and adipocyte size (each p...

  17. Receptor activity modifying proteins (RAMPs) interact with the VPAC1 receptor: evidence for differential RAMP modulation of multiple signalling pathways

    International Nuclear Information System (INIS)

    Christopoulos, G.; Morfis, M.; Sexton, P.M.; Christopoulos, A.; Laburthe, M.; Couvineau, A.

    2001-01-01

    Full text: Receptor activity modifying proteins (RAMP) constitute a family of three accessory proteins that affect the expression and/or phenotype of the calcitonin receptor (CTR) or CTR-like receptor (CRLR). In this study we screened a range of class II G protein-coupled receptors (PTH1, PTH2, GHRH, VPAC1, VPAC2 receptors) for possible RAMP interactions by measurement of receptor-induced translocation of c-myc tagged RAMP1 or HA tagged RAMP3. Of these, only the VPAC1 receptor caused significant translocation of c-myc-RAMP1 or HA-RAMP3 to the cell surface. Co-transfection of VPAC1 and RAMPs did not alter 125 I-VIP binding and specificity. VPAC1 receptor function was subsequently analyzed through parallel determinations of cAMP accumulation and phosphoinositide (PI) hydrolysis in the presence and absence of each of the three RAMPs. In contrast to CTR-RAMP interaction, where there was an increase in cAMP Pharmacologisand a decrease in PI hydrolysis, VPAC1-RAMP interaction was characterized by a specific increase in agonist-mediated PI hydrolysis when co-transfected with RAMP2. This change was due to an enhancement of Emax with no change in EC 50 value for VIP. No significant change in cAMP accumulation was observed. This is the first demonstration of an interaction of RAMPs with a G protein-coupled receptor outside the CTR family and may suggest a more generalized role for RAMPs in modulating G protein-coupled receptor signaling. Copyright (2001) Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists

  18. Novel time-dependent vascular actions of Δ9-tetrahydrocannabinol mediated by peroxisome proliferator-activated receptor gamma

    International Nuclear Information System (INIS)

    O'Sullivan, Saoirse E.; Tarling, Elizabeth J.; Bennett, Andrew J.; Kendall, David A.; Randall, Michael D.

    2005-01-01

    Cannabinoids have widespread effects on the cardiovascular system, only some of which are mediated via G-protein-coupled cell surface receptors. The active ingredient of cannabis, Δ 9 -tetrahydrocannabinol (THC), causes acute vasorelaxation in various arteries. Here we show for the first time that THC also causes slowly developing vasorelaxation through activation of peroxisome proliferator-activated receptors gamma (PPARγ). In vitro, THC (10 μM) caused time-dependent vasorelaxation of rat isolated arteries. Time-dependent vasorelaxation to THC was similar to that produced by the PPARγ agonist rosiglitazone and was inhibited by the PPARγ antagonist GW9662 (1 μM), but not the cannabinoid CB 1 receptor antagonist AM251 (1 μM). Time-dependent vasorelaxation to THC requires an intact endothelium, nitric oxide, production of hydrogen peroxide, and de novo protein synthesis. In transactivation assays in cultured HEK293 cells, THC-activated PPARγ, transiently expressed in combination with retinoid X receptor α and a luciferase reporter gene, in a concentration-dependent manner (100 nM-10 μM). In vitro incubation with THC (1 or 10 μM, 8 days) stimulated adipocyte differentiation in cultured 3T3L1 cells, a well-accepted property of PPARγ ligands. The present results provide strong evidence that THC is a PPARγ ligand, stimulation of which causes time-dependent vasorelaxation, implying some of the pleiotropic effects of cannabis may be mediated by nuclear receptors

  19. Calcium is the switch in the moonlighting dual function of the ligand-activated receptor kinase phytosulfokine receptor 1

    KAUST Repository

    Muleya, Victor

    2014-09-23

    Background: A number of receptor kinases contain guanylate cyclase (GC) catalytic centres encapsulated in the cytosolic kinase domain. A prototypical example is the phytosulfokine receptor 1 (PSKR1) that is involved in regulating growth responses in plants. PSKR1 contains both kinase and GC activities however the underlying mechanisms regulating the dual functions have remained elusive. Findings: Here, we confirm the dual activity of the cytoplasmic domain of the PSKR1 receptor. We show that mutations within the guanylate cyclase centre modulate the GC activity while not affecting the kinase catalytic activity. Using physiologically relevant Ca2+ levels, we demonstrate that its GC activity is enhanced over two-fold by Ca2+ in a concentration-dependent manner. Conversely, increasing Ca2+ levels inhibits kinase activity up to 500-fold at 100 nM Ca2+. Conclusions: Changes in calcium at physiological levels can regulate the kinase and GC activities of PSKR1. We therefore propose a functional model of how calcium acts as a bimodal switch between kinase and GC activity in PSKR1 that could be relevant to other members of this novel class of ligand-activated receptor kinases.

  20. The adipogenic acetyltransferase Tip60 targets activation function 1 of peroxisome proliferator-activated receptor gamma

    DEFF Research Database (Denmark)

    van Beekum, Olivier; Brenkman, Arjan B; Grøntved, Lars

    2008-01-01

    The transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma) plays a key role in the regulation of lipid and glucose metabolism in adipocytes, by regulating their differentiation, maintenance, and function. The transcriptional activity of PPARgamma is dictated by the set...... in cells, and through use of chimeric proteins, we established that coactivation by Tip60 critically depends on the N-terminal activation function 1 of PPARgamma, a domain involved in isotype-specific gene expression and adipogenesis. Chromatin immunoprecipitation experiments showed that the endogenous Tip...... of proteins with which this nuclear receptor interacts under specific conditions. Here we identify the HIV-1 Tat-interacting protein 60 (Tip60) as a novel positive regulator of PPARgamma transcriptional activity. Using tandem mass spectrometry, we found that PPARgamma and the acetyltransferase Tip60 interact...

  1. CORRELATION BETWEEN INTELLECTUAL PROPERTY AND SCIENTIFIC ACTIVITY

    Directory of Open Access Journals (Sweden)

    Nataliia Shust

    2017-07-01

    Full Text Available Purpose: The article is dedicated to the analysis of legal nature and peculiarities of optimal correlation between the notions of intellectual property and scientific activity. Nowadays intellectual property as institution goes through the period of establishment in Ukraine. As the Soviet system of civil law was based on recognition and regulation of authors’ rights for the authors of scientific works, discoveries, inventions and innovation proposals as the ones having mainly relative, i.e. legally mandatory, but not absolute character.  Getting started to define the notion of intellectual property and intellectual property right in the system of interaction with scientific activity, it is important to say that such notion as “intellectual property” still needs enhancement. Its imperfection is due to the fact that this kind of property implies being formed by intellectual efforts of the author of scientific work, but legally it is processed with the help of documents that guarantee property right. Methods. General scientific method, philosophical method, specially-legal method of scientific research, system analysis method. Results: It is important to emphasize that not every result of scientific or creative work can become the object of intellectual property right, but the one that corresponds with law. Any scientific work falls within the purview of law if it corresponds with law demands. Scientific and technical results obtain legal protection only in case of appropriate qualification established by specific agency of State administration and issuement of law-enforcement document being limited by the territory of Ukraine. Protection of rights on the territory of other countries is realized only on the basis of correspondent international conventions and treaties. Discussion: Advanced modern countries realized the meaning and importance of usage and proper protection of creative and scientific work results known as

  2. Plasticizers May Activate Human Hepatic Peroxisome Proliferator-Activated Receptor α Less Than That of a Mouse but May Activate Constitutive Androstane Receptor in Liver

    Science.gov (United States)

    Ito, Yuki; Nakamura, Toshiki; Yanagiba, Yukie; Ramdhan, Doni Hikmat; Yamagishi, Nozomi; Naito, Hisao; Kamijima, Michihiro; Gonzalez, Frank J.; Nakajima, Tamie

    2012-01-01

    Dibutylphthalate (DBP), di(2-ethylhexyl)phthalate (DEHP), and di(2-ethylhexyl)adipate (DEHA) are used as plasticizers. Their metabolites activate peroxisome proliferator-activated receptor (PPAR) α, which may be related to their toxicities. However, species differences in the receptor functions between rodents and human make it difficult to precisely extrapolate their toxicity from animal studies to human. In this paper, we compared the species differences in the activation of mouse and human hepatic PPARα by these plasticizers using wild-type (mPPARα) and humanized PPARα (hPPARα) mice. At 12 weeks old, each genotyped male mouse was classified into three groups, and fed daily for 2 weeks per os with corn oil (vehicle control), 2.5 or 5.0 mmol/kg DBP (696, 1392 mg/kg), DEHP (977, 1953 mg/kg), and DEHA (926, 1853 mg/kg), respectively. Generally, hepatic PPARα of mPPARα mice was more strongly activated than that of hPPARα mice when several target genes involving β-oxidation of fatty acids were evaluated. Interestingly, all plasticizers also activated hepatic constitutive androstane receptor (CAR) more in hPPARα mice than in mPPARα mice. Taken together, these plasticizers activated mouse and human hepatic PPARα as well as CAR. The activation of PPARα was stronger in mPPARα mice than in hPPARα mice, while the opposite was true of CAR. PMID:22792086

  3. Plasticizers May Activate Human Hepatic Peroxisome Proliferator-Activated Receptor α Less Than That of a Mouse but May Activate Constitutive Androstane Receptor in Liver

    Directory of Open Access Journals (Sweden)

    Yuki Ito

    2012-01-01

    Full Text Available Dibutylphthalate (DBP, di(2-ethylhexylphthalate (DEHP, and di(2-ethylhexyladipate (DEHA are used as plasticizers. Their metabolites activate peroxisome proliferator-activated receptor (PPAR α, which may be related to their toxicities. However, species differences in the receptor functions between rodents and human make it difficult to precisely extrapolate their toxicity from animal studies to human. In this paper, we compared the species differences in the activation of mouse and human hepatic PPARα by these plasticizers using wild-type (mPPARα and humanized PPARα (hPPARα mice. At 12 weeks old, each genotyped male mouse was classified into three groups, and fed daily for 2 weeks per os with corn oil (vehicle control, 2.5 or 5.0 mmol/kg DBP (696, 1392 mg/kg, DEHP (977, 1953 mg/kg, and DEHA (926, 1853 mg/kg, respectively. Generally, hepatic PPARα of mPPARα mice was more strongly activated than that of hPPARα mice when several target genes involving β-oxidation of fatty acids were evaluated. Interestingly, all plasticizers also activated hepatic constitutive androstane receptor (CAR more in hPPARα mice than in mPPARα mice. Taken together, these plasticizers activated mouse and human hepatic PPARα as well as CAR. The activation of PPARα was stronger in mPPARα mice than in hPPARα mice, while the opposite was true of CAR.

  4. Mu-opioid receptor knockout mice show diminished food-anticipatory activity

    NARCIS (Netherlands)

    Kas, Martien J H; van den Bos, Ruud; Baars, Annemarie M; Lubbers, Marianne; Lesscher, Heidi M B; Hillebrand, Jacquelien J G; Schuller, Alwin G; Pintar, John E; Spruijt, Berry M

    We have previously suggested that during or prior to activation of anticipatory behaviour to a coming reward, mu-opioid receptors are activated. To test this hypothesis schedule induced food-anticipatory activity in mu-opioid receptor knockout mice was measured using running wheels. We hypothesized

  5. Targeting the urokinase plasminogen activator receptor inhibits ovarian cancer metastasis.

    Science.gov (United States)

    Kenny, Hilary A; Leonhardt, Payton; Ladanyi, Andras; Yamada, S Diane; Montag, Anthony; Im, Hae Kyung; Jagadeeswaran, Sujatha; Shaw, David E; Mazar, Andrew P; Lengyel, Ernst

    2011-02-01

    To understand the functional and preclinical efficacy of targeting the urokinase plasminogen activator receptor (u-PAR) in ovarian cancer. Expression of u-PAR was studied in 162 epithelial ovarian cancers, including 77 pairs of corresponding primary and metastatic tumors. The effect of an antibody against u-PAR (ATN-658) on proliferation, adhesion, invasion, apoptosis, and migration was assessed in 3 (SKOV3ip1, HeyA8, and CaOV3) ovarian cancer cell lines. The impact of the u-PAR antibody on tumor weight, number, and survival was examined in corresponding ovarian cancer xenograft models and the mechanism by which ATN-658 blocks metastasis was explored. Only 8% of all ovarian tumors were negative for u-PAR expression. Treatment of SKOV3ip1, HeyA8, and CaOV3 ovarian cancer cell lines with the u-PAR antibody inhibited cell invasion, migration, and adhesion. In vivo, anti-u-PAR treatment reduced the number of tumors and tumor weight in CaOV3 and SKOV3ip1 xenografts and reduced tumor weight and increased survival in HeyA8 xenografts. Immunostaining of CaOV3 xenograft tumors and ovarian cancer cell lines showed an increase in active-caspase 3 and TUNEL staining. Treatment with u-PAR antibody inhibited α(5)-integrin and u-PAR colocalization on primary human omental extracellular matrix. Anti-u-PAR treatment also decreased the expression of urokinase, u-PAR, β(3)-integrin, and fibroblast growth factor receptor-1 both in vitro and in vivo. This study shows that an antibody against u-PAR reduces metastasis, induces apoptosis, and reduces the interaction between u-PAR and α(5)-integrin. This provides a rationale for targeting the u-PAR pathway in patients with ovarian cancer and for further testing of ATN-658 in this indication. ©2010 AACR.

  6. Development of operational models of receptor activation including constitutive receptor activity and their use to determine the efficacy of the chemokine CCL17 at the CC chemokine receptor CCR4.

    Science.gov (United States)

    Slack, R J; Hall, D A

    2012-07-01

    BACKGROUND AND PURPOSE The operational model provides a key conceptual framework for the analysis of pharmacological data. However, this model does not include constitutive receptor activity, a frequent phenomenon in modern pharmacology, particularly in recombinant systems. Here, we developed extensions of the operational model which include constitutive activity and applied them to effects of agonists at the chemokine receptor CCR4. EXPERIMENTAL APPROACH The effects of agonists of CCR4 on [(35) S]GTPγS binding to recombinant cell membranes and on the filamentous (F-) actin content of human CD4(+) CCR4(+) T cells were determined. The basal [(35) S]GTPγS binding was changed by varying the GDP concentration whilst the basal F-actin contents of the higher expressing T cell populations were elevated, suggesting constitutive activity of CCR4. Both sets of data were analysed using the mathematical models. RESULTS The affinity of CCL17 (also known as TARC) derived from analysis of the T cell data (pK(a) = 9.61 ± 0.17) was consistent with radioligand binding experiments (9.50 ± 0.11) while that from the [(35) S]GTPγS binding experiments was lower (8.27 ± 0.09). Its intrinsic efficacy differed between the two systems (110 in T cells vs. 11). CONCLUSIONS AND IMPLICATIONS The presence of constitutive receptor activity allows the absolute intrinsic efficacy of agonists to be determined without a contribution from the signal transduction system. Intrinsic efficacy estimated in this way is consistent with Furchgott's definition of this property. CCL17 may have a higher intrinsic efficacy at CCR4 in human T cells than that expressed recombinantly in CHO cells. © 2012 GSK Services Unlimited. British Journal of Pharmacology © 2012 The British Pharmacological Society.

  7. Chemical Composition, antioxidant activity, functional properties and ...

    African Journals Online (AJOL)

    Chemical Composition, antioxidant activity, functional properties and inhibitory action of unripe plantain ( M. Paradisiacae ) flour. ... of dry matter (48.00 ± 3.96%) and starch (31.10 ± 0.44%) but was low in phenol (1.42 ± 0.03%), protein (3.15 ± 0.042%), ash (5.50 ± 0.42%) and total soluble sugar (0.64 ± 0.001%) (p < 0.05).

  8. Repressive effects of resveratrol on androgen receptor transcriptional activity.

    Directory of Open Access Journals (Sweden)

    Wen-feng Shi

    2009-10-01

    Full Text Available The chemopreventive effects of resveratrol (RSV on prostate cancer have been well established; the androgen receptor (AR plays pivotal roles in prostatic tumorigenesis. However, the exact underlying molecular mechanisms about the effects of RSV on AR have not been fully elucidated. A model system is needed to determine whether and how RSV represses AR transcriptional activity.The AR cDNA was first cloned into the retroviral vector pOZ-N and then integrated into the genome of AR-negative HeLa cells to generate the AR(+ cells. The constitutively expressed AR was characterized by monitoring hormone-stimulated nuclear translocation, DNA binding, and transcriptional activation, with the AR(- cells serving as controls. AR(+ cells were treated with RSV, and both AR protein levels and AR transcriptional activity were measured simultaneously. Chromatin immunoprecipitation (ChIP assays were used to detect the effects of RSV on the recruitment of AR to its cognate element (ARE.AR in the AR (+ stable cell line functions in a manner similar to that of endogenously expressed AR. Using this model system we clearly demonstrated that RSV represses AR transcriptional activity independently of any effects on AR protein levels. However, neither the hormone-mediated nucleus translocation nor the AR/ARE interaction was affected by RSV treatment.We demonstrated unambiguously that RSV regulates AR target gene expression, at least in part, by repressing AR transcriptional activity. Repressive effects of RSV on AR activity result from mechanisms other than the affects of AR nuclear translocation or DNA binding.

  9. Allosteric regulation by oleamide of the binding properties of 5-hydroxytryptamine7 receptors.

    Science.gov (United States)

    Hedlund, P B; Carson, M J; Sutcliffe, J G; Thomas, E A

    1999-12-01

    Oleamide belongs to a family of amidated lipids with diverse biological activities, including sleep induction and signaling modulation of several 5-hydroxytryptamine (5-HT) receptor subtypes, including 5-HT1A, 5-HT2A/2C, and 5-HT7. The 5-HT7 receptor, predominantly localized in the hypothalamus, hippocampus, and frontal cortex, stimulates cyclic AMP formation and is thought to be involved in the regulation of sleep-wake cycles. Recently, it was proposed that oleamide acts at an allosteric site on the 5-HT7 receptor to regulate cyclic AMP formation. We have further investigated the interaction between oleamide and 5-HT7 receptors by performing radioligand binding assays with HeLa cells transfected with the 5-HT7 receptor. Methiothepin, clozapine, and 5-HT all displaced specific [3H]5-HT (100 nM) binding, with pK(D) values of 7.55, 7.85, and 8.39, respectively. Oleamide also displaced [3H]5-HT binding, but the maximum inhibition was only 40% of the binding. Taking allosteric (see below) cooperativity into account, a K(D) of 2.69 nM was calculated for oleamide. In saturation binding experiments, oleamide caused a 3-fold decrease in the affinity of [3H]5-HT for the 5-HT7 receptor, without affecting the number of binding sites. A Schild analysis showed that the induced shift in affinity of [3H]5-HT reached a plateau, unlike that of a competitive inhibitor, illustrating the allosteric nature of the interaction between oleamide and the 5-HT7 receptor. Oleic acid, the product of oleamide hydrolysis, had a similar effect on [3H]5-HT binding, whereas structural analogs of oleamide, trans-9,10-octadecenamide, cis-8,9-octadecenamide, and erucamide, did not alter [3H]5-HT binding significantly. The findings support the hypothesis that oleamide acts via an allosteric site on the 5-HT7 receptor regulating receptor affinity.

  10. Surface active properties of lipid nanocapsules.

    Directory of Open Access Journals (Sweden)

    Celia R A Mouzouvi

    Full Text Available Lipid nanocapsules (LNCs are biomimetic nanocarriers used for the encapsulation of a broad variety of active ingredients. Similar to surface active compounds, LNCs contain both hydrophilic and hydrophobic parts in their structure. Moreover, the components of LNCs, macrogol 15 hydroxystearate (MHS and lecithin, are known for their surface active properties. Therefore, the aim of this paper was to investigate the capability of the LNCs to decrease surface tension using two techniques: drop tensiometry and the Wilhelmy plate method. LNCs with diameters ranging from 30 to 100 nm were successfully obtained using a phase inversion technique. The LNCs' properties, such as size and zeta potential, depend on the composition. LNCs exhibit a lower limiting surface tension compared to MHS (34.8-35.0 mN/m and 37.7-38.8 mN/m, respectively, as confirmed by both drop tensiometry and the Wilhelmy plate method. LNCs have exhibited a saturated interfacial concentration (SIC that was 10-fold higher than the critical micellar concentration (CMC of MHS or the SIC of binary and ternary mixtures of LNC ingredients. The SIC of the LNC formulations depended on the mass mixing ratio of the MHS/triglycerides but not on the presence of lecithin. The CMC/SIC values measured by the Wilhelmy plate method were higher than those obtained using drop tensiometry because of the longer duration of the tensiometry measurement. In conclusion, the surfactant-like properties of the LNCs offer new possibilities for medical and pharmaceutical applications.

  11. Activation of postnatal neural stem cells requires nuclear receptor TLX.

    Science.gov (United States)

    Niu, Wenze; Zou, Yuhua; Shen, Chengcheng; Zhang, Chun-Li

    2011-09-28

    Neural stem cells (NSCs) continually produce new neurons in postnatal brains. However, the majority of these cells stay in a nondividing, inactive state. The molecular mechanism that is required for these cells to enter proliferation still remains largely unknown. Here, we show that nuclear receptor TLX (NR2E1) controls the activation status of postnatal NSCs in mice. Lineage tracing indicates that TLX-expressing cells give rise to both activated and inactive postnatal NSCs. Surprisingly, loss of TLX function does not result in spontaneous glial differentiation, but rather leads to a precipitous age-dependent increase of inactive cells with marker expression and radial morphology for NSCs. These inactive cells are mispositioned throughout the granular cell layer of the dentate gyrus during development and can proliferate again after reintroduction of ectopic TLX. RNA-seq analysis of sorted NSCs revealed a TLX-dependent global expression signature, which includes the p53 signaling pathway. TLX regulates p21 expression in a p53-dependent manner, and acute removal of p53 can rescue the proliferation defect of TLX-null NSCs in culture. Together, these findings suggest that TLX acts as an essential regulator that ensures the proliferative ability of postnatal NSCs by controlling their activation through genetic interaction with p53 and other signaling pathways.

  12. SYNTHESIS AND EVALUATION OF PHARMACOLOGICAL AND PHARMACOKINETIC PROPERTIES OF MONOPROPYL ANALOGS OF 5-[[(TRIFLUOROMETHYL)SULFONYL]OXY]-2-AMINOTETRALIN, 7-[[(TRIFLUOROMETHYL)SULFONYL]OXY]-2-AMINOTETRALIN, AND 8-[[(TRIFLUOROMETHYL)SULFONYL]OXY]-2-AMINOTETRALIN - CENTRAL DOPAMINE AND SEROTONIN RECEPTOR ACTIVITY

    NARCIS (Netherlands)

    SONESSON, C; BARF, T; NILSSON, J; DIJKSTRA, D; CARLSSON, A; SVENSSON, K; SMITH, MW; MARTIN, IJ; DUNCAN, JN; KING, LJ; WIKSTROM, H

    1995-01-01

    In order to explore further the structure-activity relationships of serotonergic and dopaminergic ligands, a series of enantiopure 5-, 7-, or 8-triflate (-OTf)-substituted 2-(monopropylamino)tetralins have been synthesized and evaluated in in vitro binding and in vivo biochemical and behavioral

  13. The bitter pill: clinical drugs that activate the human bitter taste receptor TAS2R14.

    Science.gov (United States)

    Levit, Anat; Nowak, Stefanie; Peters, Maximilian; Wiener, Ayana; Meyerhof, Wolfgang; Behrens, Maik; Niv, Masha Y

    2014-03-01

    Bitter taste receptors (TAS2Rs) mediate aversive response to toxic food, which is often bitter. These G-protein-coupled receptors are also expressed in extraoral tissues, and emerge as novel targets for therapeutic indications such as asthma and infection. Our goal was to identify ligands of the broadly tuned TAS2R14 among clinical drugs. Molecular properties of known human bitter taste receptor TAS2R14 agonists were incorporated into pharmacophore- and shape-based models and used to computationally predict additional ligands. Predictions were tested by calcium imaging of TAS2R14-transfected HEK293 cells. In vitro testing of the virtual screening predictions resulted in 30-80% success rates, and 15 clinical drugs were found to activate the TAS2R14. hERG potassium channel, which is predominantly expressed in the heart, emerged as a common off-target of bitter drugs. Despite immense chemical diversity of known TAS2R14 ligands, novel ligands and previously unknown polypharmacology of drugs were unraveled by in vitro screening of computational predictions. This enables rational repurposing of traditional and standard drugs for bitter taste signaling modulation for therapeutic indications.

  14. The non-biphenyl-tetrazole angiotensin AT1 receptor antagonist eprosartan is a unique and robust inverse agonist of the active state of the AT1 receptor.

    Science.gov (United States)

    Takezako, Takanobu; Unal, Hamiyet; Karnik, Sadashiva S; Node, Koichi

    2018-03-23

    Conditions such as hypertension and renal allograft rejection are accompanied by chronic, agonist-independent, signalling by angiotensin II AT 1 receptors. The current treatment paradigm for these diseases entails the preferred use of inverse agonist AT 1 receptor blockers (ARBs). However, variability in the inverse agonist activities of common biphenyl-tetrazole ARBs for the active state of AT 1 receptors often leads to treatment failure. Therefore, characterization of robust inverse agonist ARBs for the active state of AT 1 receptors is necessary. To identify the robust inverse agonist for active state of AT 1 receptors and its molecular mechanism, we performed site-directed mutagenesis, competition binding assay, inositol phosphate production assay and molecular modelling for both ground-state wild-type AT 1 receptors and active-state N111G mutant AT 1 receptors. Although candesartan and telmisartan exhibited weaker inverse agonist activity for N111G- compared with WT-AT 1 receptors, only eprosartan exhibited robust inverse agonist activity for both N111G- and WT- AT 1 receptors. Specific ligand-receptor contacts for candesartan and telmisartan are altered in the active-state N111G- AT 1 receptors compared with the ground-state WT-AT 1 receptors, suggesting an explanation of their attenuated inverse agonist activity for the active state of AT 1 receptors. In contrast, interactions between eprosartan and N111G-AT 1 receptors were not significantly altered, and the inverse agonist activity of eprosartan was robust. Eprosartan may be a better therapeutic option than other ARBs. Comparative studies investigating eprosartan and other ARBs for the treatment of diseases caused by chronic, agonist-independent, AT 1 receptor activation are warranted. © 2018 The British Pharmacological Society.

  15. Triclocarban mediates induction of xenobiotic metabolism through activation of the constitutive androstane receptor and the estrogen receptor alpha.

    Directory of Open Access Journals (Sweden)

    Mei-Fei Yueh

    Full Text Available Triclocarban (3,4,4'-trichlorocarbanilide, TCC is used as a broad-based antimicrobial agent that is commonly added to personal hygiene products. Because of its extensive use in the health care industry and resistance to degradation in sewage treatment processes, TCC has become a significant waste product that is found in numerous environmental compartments where humans and wildlife can be exposed. While TCC has been linked to a range of health and environmental effects, few studies have been conducted linking exposure to TCC and induction of xenobiotic metabolism through regulation by environmental sensors such as the nuclear xenobiotic receptors (XenoRs. To identify the ability of TCC to activate xenobiotic sensors, we monitored XenoR activities in response to TCC treatment using luciferase-based reporter assays. Among the XenoRs in the reporter screening assay, TCC promotes both constitutive androstane receptor (CAR and estrogen receptor alpha (ERα activities. TCC treatment to hUGT1 mice resulted in induction of the UGT1A genes in liver. This induction was dependent upon the constitutive active/androstane receptor (CAR because no induction occurred in hUGT1Car(-/- mice. Induction of the UGT1A genes by TCC corresponded with induction of Cyp2b10, another CAR target gene. TCC was demonstrated to be a phenobarbital-like activator of CAR in receptor-based assays. While it has been suggested that TCC be classified as an endocrine disruptor, it activates ERα leading to induction of Cyp1b1 in female ovaries as well as in promoter activity. Activation of ERα by TCC in receptor-based assays also promotes induction of human CYP2B6. These observations demonstrate that TCC activates nuclear xenobiotic receptors CAR and ERα both in vivo and in vitro and might have the potential to alter normal physiological homeostasis. Activation of these xenobiotic-sensing receptors amplifies gene expression profiles that might represent a mechanistic base for

  16. Sulpiride and the role of dopaminergic receptor blockade in the antipsychotic activity of neuroleptics

    Energy Technology Data Exchange (ETDEWEB)

    Memo, M; Battaini, F; Spano, P F; Trabucchi, M [University of Brescia, (Italy). Dept. of Pharmacology

    1981-01-01

    It is now generally recognized that dopamine receptors excist in the CNS as different subtypes: D/sub 1/ receptors, associated with adenylyl cyclase activity, and D/sub 2/ receptor, uncoupled to a cyclic AMP generating system. In order to understand the role of D/sub 1/ and D/sub 2/ receptors in the antipsychotic action of neuroleptics, we have performed subchronic treatment with haloperidol, a drug which acts on D/sub 1/ receptors, and sulpiride, a selective antagonist to D/sub 2/ receptors. Long-term treatment with haloperidol does not induce significant supersensitivity of the D/sub 2/ receptors. In fact under these conditions /sup 3/H-(-)-sulpiride binding, which is a marker of D/sub 2/ receptor function, does not increase in rat striatum, while the long-term administration of sulpiride, itself produces supersensitivity of D/sub 2/ receptors. Moreover, sulpiride does not induce supersensitivity of the D/sub 1/ receptors, characterized by /sup 3/H-spiroperidol binding. These data suggest that both types of dopamine receptors may be involved in the clinical antipsychotic effects of neuroleptics. Unilateral leison of the nigrostriatal dopaminergic pathway produces an increase of striatal dopaminergic receptors, measured either by /sup 3/H-spiroperidol and /sup 3/H-(-)-sulpiride binding. These findings suggest that D/sub 1/ and D/sub 2/ receptors are present in postsynaptic membranes while it is still not known whether they exist in the same cellular elements.

  17. Sulpiride and the role of dopaminergic receptor blockade in the antipsychotic activity of neuroleptics

    International Nuclear Information System (INIS)

    Memo, M.; Battaini, F.; Spano, P.F.; Trabucchi, M.

    1981-01-01

    It is now generally recognized that dopamine receptors excist in the CNS as different subtypes: D 1 receptors, associated with adenylyl cyclase activity, and D 2 receptor, uncoupled to a cyclic APM generating system. In order to understand the role of D 1 and D 2 receptors in the antipsychotic action of neuroleptics, we have performed subchronic treatment with haloperidol, a drug which acts on D 1 receptors, and sulpiride, a selective antagonist to D 2 receptors. Long-term treatment with haloperidol does not induce significant supersensitivity of the D 2 receptors. In fact under these conditions 3 H-(-)-sulpiride binding, which is a marker of D 2 receptor function, does not increase in rat striatum, while the long-term administration of sulpiride, itself produces supersensitivity of D 2 receptors. Moreover, sulpiride does not induce supersensitivity of the D 1 receptors, characterized by 3 H-spiroperidol binding. These data suggest that both types of dopamine receptors may be involved in the clinical antipsychotic effects of neuroleptics. Unilateral leison of the nigrostriatal dopaminergic pathway produces an increase of striatal dopaminergic receptors, measured either by 3 H-spiroperidol and 3 H-(-)-sulpiride binding. These findings suggest that D 1 and D 2 receptors are present in postsynaptic membranes while it is still not known whether they exist in the same cellular elements. (author)

  18. Dopaminergic receptor agents and the basal ganglia : pharmacological properties and interactions with the GABA-ergic system

    NARCIS (Netherlands)

    Timmerman, Wigerline

    1992-01-01

    In the present series of studies, attention was focussed particularly on dopaminergic D2 receptor compounds, with emphasis on the enantiomers of the potent and selective dopamine D2 receptor agonist N-0437. Drugs that display activity at D2 receptors are of great interest as potentially new

  19. Oleamide activates peroxisome proliferator-activated receptor gamma (PPARγ in vitro

    Directory of Open Access Journals (Sweden)

    Dionisi Mauro

    2012-05-01

    Full Text Available Abstract Background Oleamide (ODA is a fatty acid primary amide first identified in the cerebrospinal fluid of sleep-deprived cats, which exerts effects on vascular and neuronal tissues, with a variety of molecular targets including cannabinoid receptors and gap junctions. It has recently been reported to exert a hypolipidemic effect in hamsters. Here, we have investigated the nuclear receptor family of peroxisome proliferator-activated receptors (PPARs as potential targets for ODA action. Results Activation of PPARα, PPARβ and PPARγ was assessed using recombinant expression in Chinese hamster ovary cells with a luciferase reporter gene assay. Direct binding of ODA to the ligand binding domain of each of the three PPARs was monitored in a cell-free fluorescent ligand competition assay. A well-established assay of PPARγ activity, the differentiation of 3T3-L1 murine fibroblasts into adipocytes, was assessed using an Oil Red O uptake-based assay. ODA, at 10 and 50 μM, was able to transactivate PPARα, PPARβ and PPARγ receptors. ODA bound to the ligand binding domain of all three PPARs, although complete displacement of fluorescent ligand was only evident for PPARγ, at which an IC50 value of 38 μM was estimated. In 3T3-L1 cells, ODA, at 10 and 20 μM, induced adipogenesis. Conclusions We have, therefore, identified a novel site of action of ODA through PPAR nuclear receptors and shown how ODA should be considered as a weak PPARγ ligand in vitro.

  20. Activation of the Ca2+-sensing receptors increases currents through inward rectifier K+ channels via activation of phosphatidylinositol 4-kinase.

    Science.gov (United States)

    Liu, Chung-Hung; Chang, Hsueh-Kai; Lee, Sue-Ping; Shieh, Ru-Chi

    2016-11-01

    Inward rectifier K + channels are important for maintaining normal electrical function in many cell types. The proper function of these channels requires the presence of membrane phosphoinositide 4,5-bisphosphate (PIP 2 ). Stimulation of the Ca 2+ -sensing receptor CaR, a pleiotropic G protein-coupled receptor, activates both G q/11 , which decreases PIP 2 , and phosphatidylinositol 4-kinase (PI-4-K), which, conversely, increases PIP 2 . How membrane PIP 2 levels are regulated by CaR activation and whether these changes modulate inward rectifier K + are unknown. In this study, we found that activation of CaR by the allosteric agonist, NPSR568, increased inward rectifier K + current (I K1 ) in guinea pig ventricular myocytes and currents mediated by Kir2.1 channels exogenously expressed in HEK293T cells with a similar sensitivity. Moreover, using the fluorescent PIP 2 reporter tubby-R332H-cYFP to monitor PIP 2 levels, we found that CaR activation in HEK293T cells increased membrane PIP 2 concentrations. Pharmacological studies showed that both phospholipase C (PLC) and PI-4-K are activated by CaR stimulation with the latter played a dominant role in regulating membrane PIP 2 and, thus, Kir currents. These results provide the first direct evidence that CaR activation upregulates currents through inward rectifier K + channels by accelerating PIP 2 synthesis. The regulation of I K1 plays a critical role in the stability of the electrical properties of many excitable cells, including cardiac myocytes and neurons. Further, synthetic allosteric modulators that increase CaR activity have been used to treat hyperparathyroidism, and negative CaR modulators are of potential importance in the treatment of osteoporosis. Thus, our results provide further insight into the roles played by CaR in the cardiovascular system and are potentially valuable for heart disease treatment and drug safety.

  1. Structure-activity studies of RFamide peptides reveal subtype-selective activation of neuropeptide FF1 and FF2 receptors.

    Science.gov (United States)

    Findeisen, Maria; Rathmann, Daniel; Beck-Sickinger, Annette G

    2011-06-06

    Selectivity is a major issue in closely related multiligand/multireceptor systems. In this study we investigated the RFamide systems of hNPFF₁R and hNPFF₂R that bind the endogenous peptide hormones NPFF, NPAF, NPVF, and NPSF. By use of a systematic approach, we characterized the role of the C-terminal dipeptide with respect to agonistic properties using synthesized [Xaa 7]NPFF and [Xaa 8]NPFF analogues. We were able to identify only slight differences in potency upon changing the position of Arg 7, as all modifications resulted in identical behavior at the NPFF₁R and NPFF₂R. However, the C-terminal Phe 8 was able to be replaced by Trp or His with only a minor loss in potency at the NPFF₂R relative to the NPFF₁R. Analogues with shorter side chains, such as α-amino-4-guanidino butyric acid ([Agb 7]NPFF) or phenylglycine ([Phg 8]NPFF), decreased efficacy for the NPFF₁ R to 25-31 % of the maximal response, suggesting that these agonist-receptor complexes are more susceptible to structural modifications. In contrast, mutations to the conserved Asp 6.59 residue in the third extracellular loop of both receptors revealed a higher sensitivity toward the hNPFF₂R receptor than toward hNPFF₁R. These data provide new insight into the subtype-specific agonistic activation of the NPFF₁ and NPFF(2) receptors that are necessary for the development of selective agonists. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Molecular vibration-activity relationship in the agonism of adenosine receptors.

    Science.gov (United States)

    Chee, Hyun Keun; Oh, S June

    2013-12-01

    The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands.

  3. Molecular Vibration-Activity Relationship in the Agonism of Adenosine Receptors

    Directory of Open Access Journals (Sweden)

    Hyun Keun Chee

    2013-12-01

    Full Text Available The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands.

  4. E3 protein of bovine coronavirus is a receptor-destroying enzyme with acetylesterase activity

    International Nuclear Information System (INIS)

    Vlasak, R.; Luytjes, W.; Leider, J.; Spaan, W.; Palese, P.

    1988-01-01

    In addition to members of the Orthomyxoviridae and Paramyxoviridae, several coronaviruses have been shown to possess receptor-destroying activities. Purified bovine coronavirus (BCV) preparations have an esterase activity which inactivates O-acetylsialic acid-containing receptors on erythrocytes. Diisopropyl fluorophosphate (DFP) completely inhibits this receptor-destroying activity of BCV, suggesting that the viral enzyme is a serine esterase. Treatment of purified BCV with [ 3 H]DFP and subsequent sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the proteins revealed that the esterase/receptor-destroying activity of BCV is associated with the E3 protein was specifically phosphorylated. This finding suggests that the esterase/receptor-destroying activity of BCV is associated with the E3 protein. Furthermore, treatment of BCV with DFP dramatically reduced its infectivity in a plaque assay. It is assumed that the esterase activity of BCV is required in an early step of virus replication, possible during virus entry or uncoating

  5. E3 protein of bovine coronavirus is a receptor-destroying enzyme with acetylesterase activity

    Energy Technology Data Exchange (ETDEWEB)

    Vlasak, R.; Luytjes, W.; Leider, J.; Spaan, W.; Palese, P.

    1988-12-01

    In addition to members of the Orthomyxoviridae and Paramyxoviridae, several coronaviruses have been shown to possess receptor-destroying activities. Purified bovine coronavirus (BCV) preparations have an esterase activity which inactivates O-acetylsialic acid-containing receptors on erythrocytes. Diisopropyl fluorophosphate (DFP) completely inhibits this receptor-destroying activity of BCV, suggesting that the viral enzyme is a serine esterase. Treatment of purified BCV with (/sup 3/H)DFP and subsequent sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the proteins revealed that the esterase/receptor-destroying activity of BCV is associated with the E3 protein was specifically phosphorylated. This finding suggests that the esterase/receptor-destroying activity of BCV is associated with the E3 protein. Furthermore, treatment of BCV with DFP dramatically reduced its infectivity in a plaque assay. It is assumed that the esterase activity of BCV is required in an early step of virus replication, possible during virus entry or uncoating.

  6. Histamine receptors in human detrusor smooth muscle cells: physiological properties and immunohistochemical representation of subtypes.

    Science.gov (United States)

    Neuhaus, Jochen; Weimann, Annett; Stolzenburg, Jens-Uwe; Dawood, Waled; Schwalenberg, Thilo; Dorschner, Wolfgang

    2006-06-01

    The potent inflammatory mediator histamine is released from activated mast cells in interstitial cystitis (IC). Here, we report on the histamine receptor subtypes involved in the intracellular calcium response of cultured smooth muscle cells (cSMC). Fura-2 was used to monitor the calcium response in cSMC, cultured from human detrusor biopsies. The distribution of histamine receptor subtypes was addressed by immunocytochemistry in situ and in vitro. Histamine stimulated a maximum of 92% of the cells (n=335), being more effective than carbachol (70%, n=920). HTMT (H1R-agonist), dimaprit (H2R) and MTH (H3R) lead to significant lower numbers of reacting cells (60, 48 and 54%). Histamine receptor immunoreactivity (H1R, H2R, H3R, H4R) was found in situ and in vitro. Histamine-induced calcium increase is mediated by distinct histamine receptors. Thus, pre-therapeutic evaluation of histamine receptor expression in IC patients may help to optimize therapy by using a patient-specific cocktail of subtype-specific histamine receptor antagonists.

  7. The role of formyl peptide receptors for immunomodulatory activities of antimicrobial peptides and peptidomimetics

    DEFF Research Database (Denmark)

    Skovbakke, Sarah Line; Holdfeldt, André; Forsman, Huamei

    2018-01-01

    In recent years, the therapeutic potential of antimicrobial peptides (AMPs) as immunomodulators has become generally accepted. Nevertheless, only very few AMP-based compounds have progressed into clinical trials. This paradox may be explained by the fact, that some of the intrinsic properties...... displaying analogous immunomodulatory activity profiles. Neutrophils play key roles in host defense as major effector cells in clearance of pathogens by phagocytosis and by regulating other processes of innate immunity as well as promotion of resolution of inflammation. Several aspects of these effects...... are correlated to their expression of formyl peptide receptors (FPRs) that have been shown to be targets of both natural and synthetic antimicrobial peptides. In the present review recent findings highlighting the role of FPRs in mediating immunomodulatory activities of natural and synthetic AMPs as well...

  8. Study of the Peripheral Nerve Fibers Myelin Structure Changes during Activation of Schwann Cell Acetylcholine Receptors.

    Directory of Open Access Journals (Sweden)

    Ekaterina E Verdiyan

    Full Text Available In the present paper we consider a new type of mechanism by which neurotransmitter acetylcholine (ACh regulates the properties of peripheral nerve fibers myelin. Our data show the importance of the relationship between the changes in the number of Schwann cell (SC acetylcholine receptors (AChRs and the axon excitation (different intervals between action potentials (APs. Using Raman spectroscopy, an effect of activation of SC AChRs on the myelin membrane fluidity was investigated. It was found, that ACh stimulates an increase in lipid ordering degree of the myelin lipids, thus providing evidence for specific role of the "axon-SC" interactions at the axon excitation. It was proposed, that during the axon excitation, the SC membrane K+- depolarization and the Ca2+-influx led to phospholipase activation or exocytosis of intracellular membrane vesicles and myelin structure reorganization.

  9. Renal cells activate the platelet receptor CLEC-2 through podoplanin

    Science.gov (United States)

    Christou, Charita M.; Pearce, Andrew C.; Watson, Aleksandra A.; Mistry, Anita R.; Pollitt, Alice Y.; Fenton-May, Angharad E.; Johnson, Louise A.; Jackson, David G.; Watson, Steve P.; O'Callaghan, Chris A.

    2009-01-01

    We have recently shown that the C-type lectin-like receptor, CLEC-2, is expressed on platelets and that it mediates powerful platelet aggregation by the snake venom toxin, rhodocytin. In addition, we have provided indirect evidence for an endogenous ligand for CLEC-2 in renal cells expressing human immunodeficiency virus type 1 (HIV-1). This putative ligand facilitates transmission of HIV through its incorporation into the viral envelope and binding to CLEC-2 on platelets. The aim of this study was to identify the ligand on these cells which binds to CLEC-2 on platelets. Recombinant CLEC-2 exhibits specific binding to 293T cells in which the HIV can be grown. Further, 293T cells activate both platelets and CLEC-2-transfected DT-40 B cells. The transmembrane protein podoplanin was identified on 293T cells and demonstrated to mediate both binding of 293T cells to CLEC-2 and 293T cell activation of CLEC-2-transfected DT-40 B cells. Podoplanin is expressed on renal cells (podocytes). Further, a direct interaction between CLEC-2 and podoplanin was confirmed using surface plasmon resonance and was shown to be independent of glycosylation of CLEC-2. The interaction has an affinity of 24.5 ± 3.7μM. The present study identifies podoplanin as a ligand for CLEC-2 on renal cells. PMID:18215137

  10. Mechanical stress activates NMDA receptors in the absence of agonists.

    Science.gov (United States)

    Maneshi, Mohammad Mehdi; Maki, Bruce; Gnanasambandam, Radhakrishnan; Belin, Sophie; Popescu, Gabriela K; Sachs, Frederick; Hua, Susan Z

    2017-01-03

    While studying the physiological response of primary rat astrocytes to fluid shear stress in a model of traumatic brain injury (TBI), we found that shear stress induced Ca 2+ entry. The influx was inhibited by MK-801, a specific pore blocker of N-Methyl-D-aspartic acid receptor (NMDAR) channels, and this occurred in the absence of agonists. Other NMDA open channel blockers ketamine and memantine showed a similar effect. The competitive glutamate antagonists AP5 and GluN2B-selective inhibitor ifenprodil reduced NMDA-activated currents, but had no effect on the mechanically induced Ca 2+ influx. Extracellular Mg 2+ at 2 mM did not significantly affect the shear induced Ca 2+ influx, but at 10 mM it produced significant inhibition. Patch clamp experiments showed mechanical activation of NMDAR and inhibition by MK-801. The mechanical sensitivity of NMDARs may play a role in the normal physiology of fluid flow in the glymphatic system and it has obvious relevance to TBI.

  11. Improved Chemotherapeutic Activity by Morus alba Fruits through Immune Response of Toll-Like Receptor 4

    Directory of Open Access Journals (Sweden)

    Bo Yoon Chang

    2015-10-01

    Full Text Available Morus alba L. fruits have long been used in traditional medicine by many cultures. Their medicinal attributes include cardiovascular, hepatoprotective, neuroprotective and immunomodulatory actions. However, their mechanism of macrophage activation and anti-cancer effects remain unclear. The present study investigated the molecular mechanisms of immune stimulation and improved chemotherapeutic effect of M. alba L. fruit extract (MFE. MFE stimulated the production of cytokines, nitric oxide (NO and tumor necrosis factor-α (TNF-α and tumoricidal properties of macrophages. MFE activated macrophages through the mitogen-activated protein kinase (MAPKinase and nuclear factor-κB (NF-κB signaling pathways downstream from toll-like receptor (TLR 4. MFE was shown to exhibit cytotoxicity of CT26 cells via the activated macrophages, even though MFE did not directly affect CT26 cells. In a xenograft mouse model, MFE significantly enhanced anti-cancer activity combined with 5-fluorouracil and markedly promoted splenocyte proliferation, natural killer (NK cell activity, cytotoxic T lymphocyte (CTL activity and IFN-γ production. Immunoglobulin G (IgG antibody levels were significantly increased. These results indicate the indirect anti-cancer activity of MFE through improved immune response mediated by TLR4 signaling. M. alba L. fruit extract might be a potential anti-tumor immunomodulatory candidate chemotherapy agent.

  12. Improved Chemotherapeutic Activity by Morus alba Fruits through Immune Response of Toll-Like Receptor 4.

    Science.gov (United States)

    Chang, Bo Yoon; Kim, Seon Beom; Lee, Mi Kyeong; Park, Hyun; Kim, Sung Yeon

    2015-10-13

    Morus alba L. fruits have long been used in traditional medicine by many cultures. Their medicinal attributes include cardiovascular, hepatoprotective, neuroprotective and immunomodulatory actions. However, their mechanism of macrophage activation and anti-cancer effects remain unclear. The present study investigated the molecular mechanisms of immune stimulation and improved chemotherapeutic effect of M. alba L. fruit extract (MFE). MFE stimulated the production of cytokines, nitric oxide (NO) and tumor necrosis factor-α (TNF-α) and tumoricidal properties of macrophages. MFE activated macrophages through the mitogen-activated protein kinase (MAPKinase) and nuclear factor-κB (NF-κB) signaling pathways downstream from toll-like receptor (TLR) 4. MFE was shown to exhibit cytotoxicity of CT26 cells via the activated macrophages, even though MFE did not directly affect CT26 cells. In a xenograft mouse model, MFE significantly enhanced anti-cancer activity combined with 5-fluorouracil and markedly promoted splenocyte proliferation, natural killer (NK) cell activity, cytotoxic T lymphocyte (CTL) activity and IFN-γ production. Immunoglobulin G (IgG) antibody levels were significantly increased. These results indicate the indirect anti-cancer activity of MFE through improved immune response mediated by TLR4 signaling. M. alba L. fruit extract might be a potential anti-tumor immunomodulatory candidate chemotherapy agent.

  13. β1-adrenergic receptors activate two distinct signaling pathways in striatal neurons

    Science.gov (United States)

    Meitzen, John; Luoma, Jessie I.; Stern, Christopher M.; Mermelstein, Paul G.

    2010-01-01

    Monoamine action in the dorsal striatum and nucleus accumbens plays essential roles in striatal physiology. Although research often focuses on dopamine and its receptors, norepinephrine and adrenergic receptors are also crucial in regulating striatal function. While noradrenergic neurotransmission has been identified in the striatum, little is known regarding the signaling pathways activated by β-adrenergic receptors in this brain region. Using cultured striatal neurons, we characterized a novel signaling pathway by which activation of β1-adrenergic receptors leads to the rapid phosphorylation of cAMP Response Element Binding Protein (CREB), a transcription-factor implicated as a molecular switch underlying long-term changes in brain function. Norepinephrine-mediated CREB phosphorylation requires β1-adrenergic receptor stimulation of a receptor tyrosine kinase, ultimately leading to the activation of a Ras/Raf/MEK/MAPK/MSK signaling pathway. Activation of β1-adrenergic receptors also induces CRE-dependent transcription and increased c-fos expression. In addition, stimulation of β1-adrenergic receptors produces cAMP production, but surprisingly, β1-adrenergic receptor activation of adenylyl cyclase was not functionally linked to rapid CREB phosphorylation. These findings demonstrate that activation of β1-adrenergic receptors on striatal neurons can stimulate two distinct signaling pathways. These adrenergic actions can produce long-term changes in gene expression, as well as rapidly modulate cellular physiology. By elucidating the mechanisms by which norepinephrine and β1-adrenergic receptor activation affects striatal physiology, we provide the means to more fully understand the role of monoamines in modulating striatal function, specifically how norepinephrine and β1-adrenergic receptors may affect striatal physiology. PMID:21143600

  14. Metabolomics for informing adverse outcome pathways: Androgen receptor activation and the pharmaceutical spironolactone

    International Nuclear Information System (INIS)

    Davis, J.M.; Ekman, D.R.; Skelton, D.M.; LaLone, C.A.; Ankley, G.T.; Cavallin, J.E.; Villeneuve, D.L.; Collette, T.W.

    2017-01-01

    amino acid, tryptophan, and fatty acid metabolism. Thus, by identifying possible key events related to changes in biochemical pathways, this approach built upon an established AOP describing spironolactone’s androgenic properties and highlighted broader implications potentially unrelated to androgen receptor activation, which could form a basis for the development of an AOP network.

  15. Metabolomics for informing adverse outcome pathways: Androgen receptor activation and the pharmaceutical spironolactone

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J.M., E-mail: davis.john@epa.gov [U.S. EPA, National Exposure Research Laboratory, 960 College Station Rd., Athens, GA 30605 (United States); Ekman, D.R., E-mail: ekman.drew@epa.gov [U.S. EPA, National Exposure Research Laboratory, 960 College Station Rd., Athens, GA 30605 (United States); Skelton, D.M. [U.S. EPA, National Exposure Research Laboratory, 960 College Station Rd., Athens, GA 30605 (United States); LaLone, C.A.; Ankley, G.T.; Cavallin, J.E.; Villeneuve, D.L. [U.S. EPA, National Health and Environmental Effects Research Laboratory, 6201 Congdon Blvd., Duluth, MN 55804 (United States); Collette, T.W. [U.S. EPA, National Exposure Research Laboratory, 960 College Station Rd., Athens, GA 30605 (United States)

    2017-03-15

    affected amino acid, tryptophan, and fatty acid metabolism. Thus, by identifying possible key events related to changes in biochemical pathways, this approach built upon an established AOP describing spironolactone’s androgenic properties and highlighted broader implications potentially unrelated to androgen receptor activation, which could form a basis for the development of an AOP network.

  16. Peroxisome proliferators-activated receptor (PPAR) regulation in cardiac metabolism and disease

    NARCIS (Netherlands)

    el Azzouzi, H.

    2009-01-01

    Peroxisome proliferators-activated receptors (PPARs) are members of the nuclear receptor family of ligand activated transcription factors and consist of the three isoforms, PPAR, PPAR/ and PPAR. Considerable evidence has established the importance of PPARs in myocardial lipid homeostasis and

  17. Activation of toll-like receptors and dendritic cells by a broad range of bacterial molecules

    NARCIS (Netherlands)

    Boele, L.C.L.; Bajramovic, J.J.; Vries, A.M.M.B.C. de; Voskamp-Visser, I.A.I.; Kaman, W.E.; Kleij, D. van der

    2009-01-01

    Activation of pattern recognition receptors such as Toll-like receptors (TLRs) by pathogens leads to activation and maturation of dendritic cells (DC), which orchestrate the development of the adaptive immune response. To create an overview of the effects of a broad range of pathogenic bacteria,

  18. Plasma soluble urokinase plasminogen activator receptor in children with urinary tract infection

    DEFF Research Database (Denmark)

    Wittenhagen, Per; Andersen, Jesper Brandt; Hansen, Anita

    2011-01-01

    In this prospective study we investigated the role of plasma levels of soluble urokinase plasminogen activator receptor (suPAR) in children with urinary tract infection.......In this prospective study we investigated the role of plasma levels of soluble urokinase plasminogen activator receptor (suPAR) in children with urinary tract infection....

  19. Expression Patterns of Odorant Receptors and Response Properties of Olfactory Sensory Neurons in Aged Mice

    OpenAIRE

    Lee, Anderson C.; Tian, Huikai; Grosmaitre, Xavier; Ma, Minghong

    2009-01-01

    The sense of smell deteriorates in normal aging, but the underling mechanisms are still elusive. Here we investigated age-related alterations in expression patterns of odorant receptor (OR) genes and functional properties of olfactory sensory neurons (OSNs)—2 critical factors that define the odor detection threshold in the olfactory epithelium. Using in situ hybridization for 9 representative OR genes, we compared the cell densities of each OR in coronal nose sections at different ages (3–27 ...

  20. Modulation of receptors and adenylate cyclase activity during sucrose feeding, food deprivation, and cold exposure

    International Nuclear Information System (INIS)

    Scarpace, P.J.; Baresi, L.A.; Morley, J.E.

    1987-01-01

    Thermogenesis in brown adipose tissue (BAT) serves as a regulator of body temperature and weight maintenance. Thermogenesis can be stimulated by catecholamine activation of adenylate cyclase through the β-adrenergic receptor. To investigate the effects of sucrose feeding, food deprivation, and cold exposure on the β-adrenergic pathway, adenylate cyclase activity and β-adrenergic receptors were assessed in rat BAT after 2 wk of sucrose feeding, 2 days of food deprivation, or 2 days of cold exposure. β-Adrenergic receptors were identified in BAT using [ 125 I]iodocyanopindolol. Binding sites had the characteristics of mixed β 1 - and β 2 -type adrenergic receptors at a ratio of 60/40. After sucrose feeding or cold exposure, there was the expected increase in BAT mitochondrial mass as measured by total cytochrome-c oxidase activity but a decrease in β-adrenergic receptor density due to a loss of the β 1 -adrenergic subtype. This BAT β-adrenergic receptor downregulation was tissue specific, since myocardial β-adrenergic receptors were unchanged with either sucrose feeding or cold exposure. Forskolin-stimulated adenylate cyclase activity increased in BAT after sucrose feeding or cold exposure but not after food deprivation. These data suggest that in BAT, sucrose feeding or cold exposure result in downregulation of β-adrenergic receptors and that isoproterenol-stimulated adenylate cyclase activity was limited by receptor availability

  1. AmTAR2: Functional characterization of a honeybee tyramine receptor stimulating adenylyl cyclase activity.

    Science.gov (United States)

    Reim, Tina; Balfanz, Sabine; Baumann, Arnd; Blenau, Wolfgang; Thamm, Markus; Scheiner, Ricarda

    2017-01-01

    The biogenic monoamines norepinephrine and epinephrine regulate important physiological functions in vertebrates. Insects such as honeybees do not synthesize these neuroactive substances. Instead, they employ octopamine and tyramine for comparable physiological functions. These biogenic amines activate specific guanine nucleotide-binding (G) protein-coupled receptors (GPCRs). Based on pharmacological data obtained on heterologously expressed receptors, α- and β-adrenergic-like octopamine receptors are better activated by octopamine than by tyramine. Conversely, GPCRs forming the type 1 tyramine receptor clade (synonymous to octopamine/tyramine receptors) are better activated by tyramine than by octopamine. More recently, receptors were characterized which are almost exclusively activated by tyramine, thus forming an independent type 2 tyramine receptor clade. Functionally, type 1 tyramine receptors inhibit adenylyl cyclase activity, leading to a decrease in intracellular cAMP concentration ([cAMP] i ). Type 2 tyramine receptors can mediate Ca 2+ signals or both Ca 2+ signals and effects on [cAMP] i . We here provide evidence that the honeybee tyramine receptor 2 (AmTAR2), when heterologously expressed in flpTM cells, exclusively causes an increase in [cAMP] i . The receptor displays a pronounced preference for tyramine over octopamine. Its activity can be blocked by a series of established antagonists, of which mianserin and yohimbine are most efficient. The functional characterization of two tyramine receptors from the honeybee, AmTAR1 (previously named AmTYR1) and AmTAR2, which respond to tyramine by changing cAMP levels in opposite direction, is an important step towards understanding the actions of tyramine in honeybee behavior and physiology, particularly in comparison to the effects of octopamine. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. A urokinase receptor-associated protein with specific collagen binding properties

    DEFF Research Database (Denmark)

    Behrendt, N; Jensen, Ole Nørregaard; Engelholm, L H

    2000-01-01

    The plasminogen activation cascade system, directed by urokinase and the urokinase receptor, plays a key role in extracellular proteolysis during tissue remodeling. To identify molecular interaction partners of these trigger proteins on the cell, we combined covalent protein cross-linking with ma...

  3. Activity-induced and developmental downregulation of the Nogo receptor

    DEFF Research Database (Denmark)

    Josephson, Anna; Trifunovski, Alexandra; Schéele, Camilla

    2003-01-01

    The three axon growth inhibitory proteins, myelin associated glycoprotein, oligodendrocyte-myelin glycoprotein and Nogo-A, can all bind to the Nogo-66 receptor (NgR). This receptor is expressed by neurons with high amounts in regions of high plasticity where Nogo expression is also high. We hypot...

  4. A bacterial tyrosine phosphatase inhibits plant pattern recognition receptor activation

    Science.gov (United States)

    Perception of pathogen-associated molecular patterns (PAMPs) by surface-localised pattern-recognition receptors (PRRs) is a key component of plant innate immunity. Most known plant PRRs are receptor kinases and initiation of PAMP-triggered immunity (PTI) signalling requires phosphorylation of the PR...

  5. Proteolytic regulation of Notch1 receptor activity in cancer

    NARCIS (Netherlands)

    van Tetering, Geert

    2011-01-01

    The Notch receptor is part of a highly conserved signaling pathway essential in development and disease in embryos and adults. Notch proteins coordinate cell-cell communication through receptor-ligand interactions between adjacent cells. First Notch is cleaved in the Golgi by furin at Site-1 (S1)

  6. Deletion of thyrotropin receptor residue Asp403 in a hyperfunctioning thyroid nodule provides insight into the role of the ectodomain in ligand-induced receptor activation.

    Science.gov (United States)

    Nishihara, E; Chen, C-R; Mizutori-Sasai, Y; Ito, M; Kubota, S; Amino, N; Miyauchi, A; Rapoport, B

    2012-01-01

    Somatic mutations of the TSH receptor (TSHR) gene are the main cause of autonomously functioning thyroid nodules. Except for mutations in ectodomain residue S281, all of the numerous reported activating mutations are in the TSHR membrane-spanning region. Here, we describe a patient with a toxic adenoma with a novel heterozygous somatic mutation caused by deletion of ectodomain residue Asp403 (Del-D403). Subsequent in vitro functional studies of the Del-D403 TSHR mutation demonstrated greatly increased ligand-independent constitutive activity, 8-fold above that of the wild-type TSHR. TSH stimulation had little further effect, indicating that the mutation produced near maximal activation of the receptor. In summary, we report only the second TSHR ectodomain activating mutation (and the first ectodomain deletion mutation) responsible for development of a thyroid toxic adenoma. Because Del-D403 causes near maximal activation, our finding provides novel insight into TSHR structure and function; residue D403 is more likely to be involved in the ligand-mediated activating pathway than in the ectodomain inverse agonist property.

  7. Pregnanolone Glutamate, a Novel Use-Dependent NMDA Receptor Inhibitor, Exerts Antidepressant-Like Properties in Animal Models.

    Science.gov (United States)

    Holubova, Kristina; Nekovarova, Tereza; Pistovcakova, Jana; Sulcova, Alexandra; Stuchlík, Ales; Vales, Karel

    2014-01-01

    A number of studies demonstrated a rapid onset of an antidepressant effect of non-competitive N-methyl-d-aspartic acid receptor (NMDAR) antagonists. Nonetheless, its therapeutic potential is rather limited, due to a high coincidence of negative side-effects. Therefore, the challenge seems to be in the development of NMDAR antagonists displaying antidepressant properties, and at the same time maintaining regular physiological function of the NMDAR. Previous results demonstrated that naturally occurring neurosteroid 3α5β-pregnanolone sulfate shows pronounced inhibitory action by a use-dependent mechanism on the tonically active NMDAR. The aim of the present experiments is to find out whether the treatment with pregnanolone 3αC derivatives affects behavioral response to chronic and acute stress in an animal model of depression. Adult male mice were used throughout the study. Repeated social defeat and forced swimming tests were used as animal models of depression. The effect of the drugs on the locomotor/exploratory activity in the open-field test was also tested together with an effect on anxiety in the elevated plus maze. Results showed that pregnanolone glutamate (PG) did not induce hyperlocomotion, whereas both dizocilpine and ketamine significantly increased spontaneous locomotor activity in the open field. In the elevated plus maze, PG displayed anxiolytic-like properties. In forced swimming, PG prolonged time to the first floating. Acute treatment of PG disinhibited suppressed locomotor activity in the repeatedly defeated group-housed mice. Aggressive behavior of isolated mice was reduced after the chronic 30-day administration of PG. PG showed antidepressant-like and anxiolytic-like properties in the used tests, with minimal side-effects. Since PG combines GABAA receptor potentiation and use-dependent NMDAR inhibition, synthetic derivatives of neuroactive steroids present a promising strategy for the treatment of mood disorders. -3α5

  8. Peroxisome proliferator-activated receptor α agonist-induced down-regulation of hepatic glucocorticoid receptor expression in SD rats

    International Nuclear Information System (INIS)

    Chen Xiang; Li Ming; Sun Weiping; Bi Yan; Cai Mengyin; Liang Hua; Yu Qiuqiong; He Xiaoying; Weng Jianping

    2008-01-01

    It was reported that glucocorticoid production was inhibited by fenofibrate through suppression of type-1 11β-hydroxysteroid dehydrogenase gene expression in liver. The inhibition might be a negative-feedback regulation of glucocorticoid receptor (GR) activity by peroxisome proliferator-activated receptor alpha (PPARα), which is quickly induced by glucocorticoid in the liver. However, it is not clear if GR expression is changed by fenofibrate-induced PPARα activation. In this study, we tested this possibility in the liver of Sprague-Dawley rats. GR expression was reduced by fenofibrate in a time- and does-dependent manner. The inhibition was observed in liver, but not in fat and muscle. The corticosterone level in the blood was increased significantly by fenofibrate. These effects of fenofibrate were abolished by PPARα inhibitor MK886, suggesting that fenofibrate activated through PPARα. In conclusion, inhibition of GR expression may represent a new molecular mechanism for the negative feedback regulation of GR activity by PPARα

  9. In vivo interactions between α7 nicotinic acetylcholine receptor and nuclear peroxisome proliferator-activated receptor-α: Implication for nicotine dependence.

    Science.gov (United States)

    Jackson, Asti; Bagdas, Deniz; Muldoon, Pretal P; Lichtman, Aron H; Carroll, F Ivy; Greenwald, Mark; Miles, Michael F; Damaj, M Imad

    2017-05-15

    Chronic tobacco use dramatically increases health burdens and financial costs. Limitations of current smoking cessation therapies indicate the need for improved molecular targets. The main addictive component of tobacco, nicotine, exerts its dependency effects via nicotinic acetylcholine receptors (nAChRs). Activation of the homomeric α7 nAChR reduces nicotine's rewarding properties in conditioned place preference (CPP) test and i.v. self-administration models, but the mechanism underlying these effects is unknown. Recently, the nuclear receptor peroxisome proliferator-activated receptor type-α (PPARα) has been implicated as a downstream signaling target of the α7 nAChR in ventral tegmental area dopamine cells. The present study investigated PPARα as a possible mediator of the effect of α7 nAChR activation in nicotine dependence. Our results demonstrate the PPARα antagonist GW6471 blocks actions of the α7 nAChR agonist PNU282987 on nicotine reward in an unbiased CPP test in male ICR adult mice. These findings suggests that α7 nAChR activation attenuates nicotine CPP in a PPARα-dependent manner. To evaluate PPARα activation in nicotine dependence we used the selective and potent PPARα agonist, WY-14643 and the clinically used PPARα activator, fenofibrate, in nicotine CPP and we observed attenuation of nicotine preference, but fenofibrate was less potent. We also studied PPARα in nicotine dependence by evaluating its activation in nicotine withdrawal. WY-14643 reversed nicotine withdrawal signs whereas fenofibrate had modest efficacy. This suggests that PPARα plays a role in nicotine reward and withdrawal and that further studies are warranted to elucidate its function in mediating the effects of α7 nAChRs in nicotine dependence. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Protease-activated receptor-2 activation exaggerates TRPV1-mediated cough in guinea pigs.

    Science.gov (United States)

    Gatti, Raffaele; Andre, Eunice; Amadesi, Silvia; Dinh, Thai Q; Fischer, Axel; Bunnett, Nigel W; Harrison, Selena; Geppetti, Pierangelo; Trevisani, Marcello

    2006-08-01

    A lowered threshold to the cough response frequently accompanies chronic airway inflammatory conditions. However, the mechanism(s) that from chronic inflammation results in a lowered cough threshold is poorly understood. Irritant agents, including capsaicin, resiniferatoxin, and citric acid, elicit cough in humans and in experimental animals through the activation of the transient receptor potential vanilloid 1 (TRPV1). Protease-activated receptor-2 (PAR2) activation plays a role in inflammation and sensitizes TRPV1 in cultured sensory neurons by a PKC-dependent pathway. Here, we have investigated whether PAR2 activation exaggerates TRPV1-dependent cough in guinea pigs and whether protein kinases are involved in the PAR2-induced cough modulation. Aerosolized PAR2 agonists (PAR2-activating peptide and trypsin) did not produce any cough per se. However, they potentiated citric acid- and resiniferatoxin-induced cough, an effect that was completely prevented by the TRPV1 receptor antagonist capsazepine. In contrast, cough induced by hypertonic saline, a stimulus that provokes cough in a TRPV1-independent manner, was not modified by aerosolized PAR2 agonists. The PKC inhibitor GF-109203X, the PKA inhibitor H-89, and the cyclooxygenase inhibitor indomethacin did not affect cough induced by TRPV1 agonists, but abated the exaggeration of this response produced by PAR2 agonists. In conclusion, PAR2 stimulation exaggerates TRPV1-dependent cough by activation of diverse mechanism(s), including PKC, PKA, and prostanoid release. PAR2 activation, by sensitizing TRPV1 in primary sensory neurons, may play a role in the exaggerated cough observed in certain airways inflammatory diseases such as asthma and chronic obstructive pulmonary disease.

  11. Characterization of human endothelial cell urokinase-type plasminogen activator receptor protein and messenger RNA

    DEFF Research Database (Denmark)

    Barnathan, E S; Kuo, A; Karikó, K

    1990-01-01

    Human umbilical vein endothelial cells in culture (HUVEC) express receptors for urokinase-type plasminogen activators (u-PA). The immunochemical nature of this receptor and its relationship to u-PA receptors expressed by other cell types is unknown. Cross-linking active site-blocked u-PA to HUVEC...... an endothelial cell cDNA library using the polymerase chain reaction (PCR) and oligonucleotide primers corresponding to the DNA sequence of the receptor cloned from transformed human fibroblasts (Roldan et al, EMBO J 9:467, 1990). The size of the cDNA (approximately 1,054 base pairs, bp) and the presence...

  12. Ignition properties of nuclear grade activated carbons

    International Nuclear Information System (INIS)

    Freeman, W.P.; Hunt, J.R.; Kovach, J.L.

    1983-01-01

    The ignition property of new activated carbons used in air cleaning systems of nuclear facilities has been evaluated in the past, however very little information has been generated on the behavior of aged, weathered carbons which have been exposed to normal nuclear facility environment. Additionally the standard procedure for evaluation of ignition temperature of carbon is performed under very different conditions than those used in the design of nuclear air cleaning systems. Data were generated evaluating the ageing of activated carbons and comparing their CH 3 131 I removal histories to their ignition temperatures. A series of tests were performed on samples from one nuclear power reactor versus use time, a second series evaluated samples from several plants showing the variability of atmospheric effects. The ignition temperatures were evaluated simulating the conditions existing in nuclear air cleaning systems, such as velocity, bed depth, etc., to eliminate potential confusion resulting from artifically set current standard conditions

  13. Function of the cytoplasmic tail of human calcitonin receptor-like receptor in complex with receptor activity-modifying protein 2

    Energy Technology Data Exchange (ETDEWEB)

    Kuwasako, Kenji, E-mail: kuwasako@fc.miyazaki-u.ac.jp [Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692 (Japan); Kitamura, Kazuo; Nagata, Sayaka; Hikosaka, Tomomi [Division of Circulation and Body Fluid Regulation, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692 (Japan); Kato, Johji [Frontier Science Research Center, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692 (Japan)

    2010-02-12

    Receptor activity-modifying protein 2 (RAMP2) enables calcitonin receptor-like receptor (CRLR) to form an adrenomedullin (AM)-specific receptor. Here we investigated the function of the cytoplasmic C-terminal tail (C-tail) of human (h)CRLR by co-transfecting its C-terminal mutants into HEK-293 cells stably expressing hRAMP2. Deleting the C-tail from CRLR disrupted AM-evoked cAMP production or receptor internalization, but did not affect [{sup 125}I]AM binding. We found that CRLR residues 428-439 are required for AM-evoked cAMP production, though deleting this region had little effect on receptor internalization. Moreover, pretreatment with pertussis toxin (100 ng/mL) led to significant increases in AM-induced cAMP production via wild-type CRLR/RAMP2 complexes. This effect was canceled by deleting CRLR residues 454-457, suggesting Gi couples to this region. Flow cytometric analysis revealed that CRLR truncation mutants lacking residues in the Ser/Thr-rich region extending from Ser{sup 449} to Ser{sup 467} were unable to undergo AM-induced receptor internalization and, in contrast to the effect on wild-type CRLR, overexpression of GPCR kinases-2, -3 and -4 failed to promote internalization of CRLR mutants lacking residues 449-467. Thus, the hCRLR C-tail is crucial for AM-evoked cAMP production and internalization of the CRLR/RAMP2, while the receptor internalization is dependent on the aforementioned GPCR kinases, but not Gs coupling.

  14. Synthesis and in vivo evaluation of [11C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors

    International Nuclear Information System (INIS)

    Dumont, Filip; Waterhouse, Rikki N.; Montoya, Julie A.; Mattner, Filomena; Katsifis, Andrew; Kegeles, Lawrence S.; Laruelle, Marc

    2003-01-01

    The synthesis and evaluation of [ 11 C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors, is reported herein. The reaction of desmethylzolpidem with [ 11 C] methyl iodide afforded the title compound [ 11 C]zolpidem in a yield of 19.19 ± 3.23% in 41 ± 2 min in specific activities of 0.995-1.19 Ci/μmol (1.115 ± 0.105 Ci/μmol) (n = 3; decay corrected, EOB). The amount of radioactivity in the brain after tail vein injection in male Wistar rats was low, and the regional distribution was homogeneous and not consistent with the known distribution of the central benzodiazepine receptors. The frontal cortex/cerebellum ratio was not significantly greater than one (1.007 ± 0.266 at 5 min) and did not increase from 5 to 40 min post-injection. A PET brain imaging study in one baboon confirmed the results obtained in rats. Therefore, it can be concluded that [ 11 C]zolpidem is not a suitable tracer for in vivo visualization of central benzodiazepine receptors

  15. Synthesis and in vivo evaluation of [{sup 11}C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Dumont, Filip; Waterhouse, Rikki N. E-mail: rnw7@columbia.edu; Montoya, Julie A.; Mattner, Filomena; Katsifis, Andrew; Kegeles, Lawrence S.; Laruelle, Marc

    2003-05-01

    The synthesis and evaluation of [{sup 11}C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors, is reported herein. The reaction of desmethylzolpidem with [{sup 11}C] methyl iodide afforded the title compound [{sup 11}C]zolpidem in a yield of 19.19 {+-} 3.23% in 41 {+-} 2 min in specific activities of 0.995-1.19 Ci/{mu}mol (1.115 {+-} 0.105 Ci/{mu}mol) (n = 3; decay corrected, EOB). The amount of radioactivity in the brain after tail vein injection in male Wistar rats was low, and the regional distribution was homogeneous and not consistent with the known distribution of the central benzodiazepine receptors. The frontal cortex/cerebellum ratio was not significantly greater than one (1.007 {+-} 0.266 at 5 min) and did not increase from 5 to 40 min post-injection. A PET brain imaging study in one baboon confirmed the results obtained in rats. Therefore, it can be concluded that [{sup 11}C]zolpidem is not a suitable tracer for in vivo visualization of central benzodiazepine receptors.

  16. Synthesis and in vivo evaluation of [11C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors.

    Science.gov (United States)

    Dumont, Filip; Waterhouse, Rikki N; Montoya, Julie A; Mattner, Filomena; Katsifis, Andrew; Kegeles, Lawrence S; Laruelle, Marc

    2003-05-01

    The synthesis and evaluation of [(11)C]zolpidem, an imidazopyridine with agonist properties at central benzodiazepine receptors, is reported herein. The reaction of desmethylzolpidem with [(11)C] methyl iodide afforded the title compound [(11)C]zolpidem in a yield of 19.19 +/- 3.23% in 41 +/- 2 min in specific activities of 0.995-1.19 Ci/micromol (1.115 +/- 0.105 Ci/micromol) (n = 3; decay corrected, EOB). The amount of radioactivity in the brain after tail vein injection in male Wistar rats was low, and the regional distribution was homogeneous and not consistent with the known distribution of the central benzodiazepine receptors. The frontal cortex/cerebellum ratio was not significantly greater than one (1.007 +/- 0.266 at 5 min) and did not increase from 5 to 40 min post-injection. A PET brain imaging study in one baboon confirmed the results obtained in rats. Therefore, it can be concluded that [(11)C]zolpidem is not a suitable tracer for in vivo visualization of central benzodiazepine receptors.

  17. Kappa-opioid receptors mediate the antidepressant-like activity of hesperidin in the mouse forced swimming test.

    Science.gov (United States)

    Filho, Carlos B; Del Fabbro, Lucian; de Gomes, Marcelo G; Goes, André T R; Souza, Leandro C; Boeira, Silvana P; Jesse, Cristiano R

    2013-01-05

    The opioid system has been implicated as a contributing factor for major depression and is thought to play a role in the mechanism of action of antidepressants. This study investigated the involvement of the opioid system in the antidepressant-like effect of hesperidin in the mouse forced swimming test. Our results demonstrate that hesperidin (0.1, 0.3 and 1 mg/kg; intraperitoneal) decreased the immobility time in the forced swimming test without affecting locomotor activity in the open field test. The antidepressant-like effect of hesperidin (0.3 mg/kg) in the forced swimming test was prevented by pretreating mice with naloxone (1 mg/kg, a nonselective opioid receptor antagonist) and 2-(3,4-dichlorophenyl)-Nmethyl-N-[(1S)-1-(3-isothiocyanatophenyl)-2-(1-pyrrolidinyl)ethyl] acetamide (DIPPA (1 mg/kg), a selective κ-opioid receptor antagonist), but not with naloxone methiodide (1 mg/kg, a peripherally acting opioid receptor antagonist), naltrindole (3 mg/kg, a selective δ-opioid receptor antagonist), clocinnamox (1 mg/kg, a selective μ-opioid receptor antagonist) or caffeine (3 mg/kg, a nonselective adenosine receptor antagonist). In addition, a sub-effective dose of hesperidin (0.01 mg/kg) produced a synergistic antidepressant-like effect in the forced swimming test when combined with a sub-effective dose of morphine (1 mg/kg). The antidepressant-like effect of hesperidin in the forced swimming test on mice was dependent on its interaction with the κ-opioid receptor, but not with the δ-opioid, μ-opioid or adenosinergic receptors. Taken together, these results suggest that hesperidin possesses antidepressant-like properties and may be of interest as a therapeutic agent for the treatment of depressive disorders. Published by Elsevier B.V.

  18. Androgen receptor activation: a prospective therapeutic target for bladder cancer?

    Science.gov (United States)

    Mizushima, Taichi; Tirador, Kathleen A; Miyamoto, Hiroshi

    2017-03-01

    Patients with non-muscle-invasive or muscle-invasive bladder cancer undergoing surgery and currently available conventional therapy remain having a high risk of tumor recurrence or progression, respectively. Novel targeted molecular therapy is therefore expected to improve patient outcomes. Meanwhile, substantially higher incidence of bladder cancer in men has prompted research on androgen-mediated androgen receptor (AR) signaling in this malignancy. Indeed, preclinical evidence has suggested that AR signaling plays an important role in urothelial carcinogenesis and tumor outgrowth as well as resistance to some of the currently available conventional non-surgical therapies. Areas covered: We summarize and discuss available data suggesting the involvement of AR and its potential downstream targets in the development and progression of bladder cancer. Associations between AR signaling and sensitivity to cisplatin/doxorubicin or bacillus Calmette-Guérin treatment are also reviewed. Expert opinion: AR activation is likely to correlate with the promotion of urothelial carcinogenesis and cancer outgrowth as well as resistance to conventional therapies. Molecular therapy targeting the AR may thus provide effective chemopreventive and therapeutic approaches for urothelial cancer. Accordingly, bladder cancer can now be considered as an endocrine-related neoplasm. Clinical application of various anti-AR therapies available for AR-dependent prostate cancer to bladder cancer patients is anticipated.

  19. Induction of aryl hydrocarbon receptor-mediated and estrogen receptor-mediated activities, and modulation of cell proliferation by dinaphthofurans

    Czech Academy of Sciences Publication Activity Database

    Vondráček, Jan; Chramostová, Kateřina; Plíšková, M.; Bláha, L.; Brack, W.; Kozubík, Alois; Machala, M.

    2004-01-01

    Roč. 23, č. 9 (2004), s. 2214-2220 ISSN 0730-7268 R&D Projects: GA ČR GA525/03/1527 Institutional research plan: CEZ:AV0Z5004920 Keywords : aryl hydrocarbon receptor-mediated activity * estrogenicity * intercellular communication inhibition Subject RIV: BO - Biophysics Impact factor: 2.121, year: 2004

  20. A crosstalk between muscarinic and CRF2 receptors regulates cellular adhesion properties of human colon cancer cells.

    Science.gov (United States)

    Pelissier-Rota, M; Chartier, N T; Bonaz, B; Jacquier-Sarlin, M R

    2017-07-01

    Patients with inflammatory bowel disease often suffer from chronic and relapsing intestinal inflammation that favor the development of colitis associated cancer. An alteration of the epithelial intestinal barrier function observed in IBD is supposed to be a consequence of stress. It has been proposed that corticotrophin-releasing factor receptor (CRF2), one of the two receptors of CRF, the principal neuromediator of stress, acts on cholinergic nerves to induce stress-mediated epithelial barrier dysfunction. Non-neuronal acetylcholine (Ach) and muscarinic receptors (mAchR) also contribute to alterations of epithelial cell functions. In this study, we investigated the mechanisms through which stress and Ach modulate epithelial cell adhesive properties. We show that Ach-induced activation of mAchR in HT-29 cells results in cell dissociation together with changes in cell-matrix contacts, which correlates with the acquisition of invasive potential consistent with a matrix metalloproteinase (MMP) mode of invasion. These processes result from mAchR subsequent stimulation of the cascade of src/Erk and FAK activation. Ach-induced secretion of laminin 332 leads to α3β1 integrin activation and RhoA-dependent reorganization of the actin cytoskeleton. We show that Ach-mediated effects on cell adhesion are blocked by astressin 2b, a CRF2 antagonist, suggesting that Ach action depends partly on CRF2 signaling. This is reinforced by the fact that Ach-mediated activation of mAchR stimulates both the synthesis and the release of CRF2 ligands in HT-29 cells (effects blocked by atropine). In summary, our data provides evidence for a novel intracellular circuit involving mAchR acting on CRF2-signaling that could mediate colonic mucosal barrier dysfunction and exacerbate mucosal inflammation. Copyright © 2017. Published by Elsevier B.V.

  1. Quantitative structure-activity relationships of selective antagonists of glucagon receptor using QuaSAR descriptors.

    Science.gov (United States)

    Manoj Kumar, Palanivelu; Karthikeyan, Chandrabose; Hari Narayana Moorthy, Narayana Subbiah; Trivedi, Piyush

    2006-11-01

    In the present paper, quantitative structure activity relationship (QSAR) approach was applied to understand the affinity and selectivity of a novel series of triaryl imidazole derivatives towards glucagon receptor. Statistically significant and highly predictive QSARs were derived for glucagon receptor inhibition by triaryl imidazoles using QuaSAR descriptors of molecular operating environment (MOE) employing computer-assisted multiple regression procedure. The generated QSAR models revealed that factors related to hydrophobicity, molecular shape and geometry predominantly influences glucagon receptor binding affinity of the triaryl imidazoles indicating the relevance of shape specific steric interactions between the molecule and the receptor. Further, QSAR models formulated for selective inhibition of glucagon receptor over p38 mitogen activated protein (MAP) kinase of the compounds in the series highlights that the same structural features, which influence the glucagon receptor affinity, also contribute to their selective inhibition.

  2. Phytochemicals from Ruta graveolens Activate TAS2R Bitter Taste Receptors and TRP Channels Involved in Gustation and Nociception

    Directory of Open Access Journals (Sweden)

    Giuseppe Mancuso

    2015-10-01

    Full Text Available Ruta graveolens (rue is a spontaneous plant in the Mediterranean area with a strong aroma and a very intense bitter taste, used in gastronomy and in folk medicine. From the leaves, stems and fruits of rue, we isolated rutin, rutamarin, three furanocoumarins, two quinolinic alkaloids, a dicoumarin and two long chain ketones. Bitter taste and chemesthetic properties have been evaluated by in vitro assays with twenty receptors of the TAS2R family and four TRP ion channels involved in gustation and nociception. Among the alkaloids, skimmianine was active as a specific agonist of T2R14, whereas kokusaginin did not activate any of the tested receptors. The furanocoumarins activates TAS2R10, 14, and 49 with different degrees of selectivity, as well as the TRPA1 somatosensory ion channel. Rutamarin is an agonist of TRPM5 and TRPV1 and a strong antagonist of TRPM8 ion channels.

  3. Phytochemicals from Ruta graveolens Activate TAS2R Bitter Taste Receptors and TRP Channels Involved in Gustation and Nociception.

    Science.gov (United States)

    Mancuso, Giuseppe; Borgonovo, Gigliola; Scaglioni, Leonardo; Bassoli, Angela

    2015-10-16

    Ruta graveolens (rue) is a spontaneous plant in the Mediterranean area with a strong aroma and a very intense bitter taste, used in gastronomy and in folk medicine. From the leaves, stems and fruits of rue, we isolated rutin, rutamarin, three furanocoumarins, two quinolinic alkaloids, a dicoumarin and two long chain ketones. Bitter taste and chemesthetic properties have been evaluated by in vitro assays with twenty receptors of the TAS2R family and four TRP ion channels involved in gustation and nociception. Among the alkaloids, skimmianine was active as a specific agonist of T2R14, whereas kokusaginin did not activate any of the tested receptors. The furanocoumarins activates TAS2R10, 14, and 49 with different degrees of selectivity, as well as the TRPA1 somatosensory ion channel. Rutamarin is an agonist of TRPM5 and TRPV1 and a strong antagonist of TRPM8 ion channels.

  4. A macrocyclic ligand as receptor and Zn(II)-complex receptor for anions in water: binding properties and crystal structures.

    Science.gov (United States)

    Ambrosi, Gianluca; Formica, Mauro; Fusi, Vieri; Giorgi, Luca; Macedi, Eleonora; Micheloni, Mauro; Paoli, Paola; Pontellini, Roberto; Rossi, Patrizia

    2011-02-01

    Binding properties of 24,29-dimethyl-6,7,15,16-tetraoxotetracyclo[19.5.5.0(5,8).0(14,17)]-1,4,9,13,18,21,24,29-octaazaenatriaconta-Δ(5,8),Δ(14,17)-diene ligand L towards Zn(II) and anions, such as the halide series and inorganic oxoanions (phosphate (Pi), sulfate, pyrophosphate (PPi), and others), were investigated in aqueous solution; in addition, the Zn(II)/L system was tested as a metal-ion-based receptor for the halide series. Ligand L is a cryptand receptor incorporating two squaramide functions in an over-structured chain that connects two opposite nitrogen atoms of the Me(2)[12]aneN(4) polyaza macrocyclic base. It binds Zn(II) to form mononuclear species in which the metal ion, coordinated by the Me(2)[12]aneN(4) moiety, lodges inside the three-dimensional cavity. Zn(II)-containing species are able to bind chloride and fluoride at the physiologically important pH value of 7.4; the anion is coordinated to the metal center but the squaramide units play the key role in stabilizing the anion through a hydrogen-bonding network; two crystal structures reported here clearly show this aspect. Free L is able to bind fluoride, chloride, bromide, sulfate, Pi, and PPi in aqueous solution. The halides are bound at acidic pH, whereas the oxoanions are bound in a wide range of pH values ranging from acidic to basic. The cryptand cavity, abundant in hydrogen-bonding sites at all pH values, allows excellent selectivity towards Pi to be achieved mainly at physiological pH 7.4. By joining amine and squaramide moieties and using this preorganized topology, it was possible, with preservation of the solubility of the receptor, to achieve a very wide pH range in which oxoanions can be bound. The good selectivity towards Pi allows its discrimination in a manner not easily obtainable with nonmetallic systems in aqueous environment. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Silymarin ameliorates metabolic dysfunction associated with Diet-induced Obesity via activation of farnesyl X receptor

    Directory of Open Access Journals (Sweden)

    Ming Gu

    2016-09-01

    Full Text Available AbstractBACKGROUND AND PURPOSESilymarin, a standardized extract of the milk thistle seeds, has been widely used to treat chronic hepatitis, cirrhosis and other types of toxic liver damage. . Despite increasing studies on the action of silymarin and its major active constituent, silybin in their therapeutic properties against insulin resistance, diabetes and hyperlipidaemia in vitro and in vivo, the mechanism underlying silymarin action remains unclear. EXPERIMENTAL APPROACHC57BL/6 mice were fed high-fat diet (HFD for 3 months to induce obesity, insulin resistance, hyperlipidaemia and fatty liver. These mice were then continuously treated with HFD alone or mixed with silymarin at 40 mg/100 g for additional 6 weeks. Biochemical analysis was used to test the serum lipid and bile acid profiles. FXR and NF-κB transactivities were analysed in liver using a gene reporter assay based onquantitative RT-PCR.KEY RESULTSSilymarin treatment ameliorated insulin resistance, dyslipidaemia and inflammation, and reconstituted the bile acid pool in liver of diet-induced obesity. Associated with this, silybin and silymarin enhanced FXR transactivity. Consistently, in HepG2 cells, silybin inhibited NF-κB signalling, which was enhanced by FXR activation. CONCLUSIONS AND IMPLICATIONSOur results suggest that silybin is an effective component of silymarin for treating metabolic syndrome by stimulating FXR signalling. Key words: silymarin; silybin; metabolic syndrome; non-alcoholic fatty liver disease; farnesyl X receptorAbbreviationsALT, alanine aminotransferase; AST, aspartate transaminase; BA, bile acid; DIO, diet-induced obesity; CA, cholic acid; DMSO, dimethylsulfoxide; FXR, farnesyl X receptor; HDL-c, high density lipoprotein cholesterol; HF, high-fat; IPITT, intraperitoneal insulin tolerance test; LDL-c, low density lipoprotein cholesterol; NAFLD, non-alcoholic fatty liver disease; NF-κB, nuclear factor kappa B; NR, nuclear receptor; MS, metabolic syndrome

  6. Differential Regulation of Receptor Activation and Agonist Selectivity by Highly Conserved Tryptophans in the Nicotinic Acetylcholine Receptor Binding Site

    OpenAIRE

    Williams, Dustin K.; Stokes, Clare; Horenstein, Nicole A.; Papke, Roger L.

    2009-01-01

    We have shown previously that a highly conserved Tyr in the nicotinic acetylcholine receptor (nAChR) ligand-binding domain (LBD) (α7 Tyr188 or α4 Tyr195) differentially regulates the activity of acetylcholine (ACh) and the α7-selective agonist 3-(4-hydroxy,2-methoxybenzylidene)anabaseine (4OH-GTS-21) in α4β2 and α7 nAChR. In this study, we mutated two highly conserved LBD Trp residues in human α7 and α4β2 and expressed the receptors in Xenopus laevis oocytes. α7 Re...

  7. Sulindac metabolites inhibit epidermal growth factor receptor activation and expression

    Directory of Open Access Journals (Sweden)

    Ahnen Dennis

    2005-01-01

    Full Text Available Abstract Background Regular use of nonsteroidal anti-inflammatory drugs (NSAIDs is associated with a decreased mortality from colorectal cancer (CRC. NSAIDs induce apoptotic cell death in colon cancer cells in vitro and inhibit growth of neoplastic colonic mucosa in vivo however, the biochemical mechanisms required for these growth inhibitory effects are not well defined. We previously reported that metabolites of the NSAID sulindac downregulate extracellular-signal regulated kinase 1/2 (ERK1/2 signaling and that this effect is both necessary and sufficient for the apoptotic effects of these drugs. The goal of this project was to specifically test the hypothesis that sulindac metabolites block activation and/or expression of the epidermal growth factor (EGF receptor (EGFR. Methods HT29 human colon cancer cells were treated with EGF, alone, or in the presence of sulindac sulfide or sulindac sulfone. Cells lysates were assayed by immunoblotting for phosphorylated EGFR (pEGFR, pY1068, total EGFR, phosphorylated ERK1/2 (pERK1/2, total ERK1/2, activated caspase-3, and α-tubulin. Results EGF treatment rapidly induced phosphorylation of both EGFR and ERK1/2 in HT29 colon cancer cells. Pretreatment with sulindac metabolites for 24 h blocked EGF-induced phosphorylation of both EGFR and ERK1/2 and decreased total EGFR protein expression. Under basal conditions, downregulation of pEGFR and total EGFR was detected as early as 12 h following sulindac sulfide treatment and persisted through at least 48 h. Sulindac sulfone induced downregulation of pEGFR and total EGFR was detected as early as 1 h and 24 h, respectively, following drug treatment, and persisted through at least 72 h. EGFR downregulation by sulindac metabolites was observed in three different CRC cell lines, occurred prior to the observed downregulation of pERK1/2 and induction of apoptosis by these drugs, and was not dependent of caspase activation. Conclusion These results suggest that

  8. Ligand-independent Thrombopoietin Mutant Receptor Requires Cell Surface Localization for Endogenous Activity*

    OpenAIRE

    Marty, Caroline; Chaligné, Ronan; Lacout, Catherine; Constantinescu, Stefan N.; Vainchenker, William; Villeval, Jean-Luc

    2009-01-01

    The activating W515L mutation in the thrombopoietin receptor (MPL) has been identified in primary myelofibrosis and essential thrombocythemia. MPL belongs to a subset of the cytokine receptor superfamily that requires the JAK2 kinase for signaling. We examined whether the ligand-independent MPLW515L mutant could signal intracellularly. Addition of the endoplasmic reticulum (ER) retention KDEL sequence to the receptor C terminus efficiently locked MPLW515L within its na...

  9. Molecular Vibration-Activity Relationship in the Agonism of Adenosine Receptors

    OpenAIRE

    Chee, Hyun Keun; Oh, S. June

    2013-01-01

    The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine ...

  10. Negative Correlation between the Diffusion Coefficient and Transcriptional Activity of the Glucocorticoid Receptor.

    Science.gov (United States)

    Mikuni, Shintaro; Yamamoto, Johtaro; Horio, Takashi; Kinjo, Masataka

    2017-08-25

    The glucocorticoid receptor (GR) is a transcription factor, which interacts with DNA and other cofactors to regulate gene transcription. Binding to other partners in the cell nucleus alters the diffusion properties of GR. Raster image correlation spectroscopy (RICS) was applied to quantitatively characterize the diffusion properties of EGFP labeled human GR (EGFP-hGR) and its mutants in the cell nucleus. RICS is an image correlation technique that evaluates the spatial distribution of the diffusion coefficient as a diffusion map. Interestingly, we observed that the averaged diffusion coefficient of EGFP-hGR strongly and negatively correlated with its transcriptional activities in comparison to that of EGFP-hGR wild type and mutants with various transcriptional activities. This result suggests that the decreasing of the diffusion coefficient of hGR was reflected in the high-affinity binding to DNA. Moreover, the hyper-phosphorylation of hGR can enhance the transcriptional activity by reduction of the interaction between the hGR and the nuclear corepressors.

  11. Adenosine A2A Receptor Modulates the Activity of Globus Pallidus Neurons in Rats

    Directory of Open Access Journals (Sweden)

    Hui-Ling Diao

    2017-11-01

    Full Text Available The globus pallidus is a central nucleus in the basal ganglia motor control circuit. Morphological studies have revealed the expression of adenosine A2A receptors in the globus pallidus. To determine the modulation of adenosine A2A receptors on the activity of pallidal neurons in both normal and parkinsonian rats, in vivo electrophysiological and behavioral tests were performed in the present study. The extracellular single unit recordings showed that micro-pressure administration of adenosine A2A receptor agonist, CGS21680, regulated the pallidal firing activity. GABAergic neurotransmission was involved in CGS21680-induced modulation of pallidal neurons via a PKA pathway. Furthermore, application of two adenosine A2A receptor antagonists, KW6002 or SCH442416, mainly increased the spontaneous firing of pallidal neurons, suggesting that endogenous adenosine system modulates the activity of pallidal neurons through adenosine A2A receptors. Finally, elevated body swing test (EBST showed that intrapallidal microinjection of adenosine A2A receptor agonist/antagonist induced ipsilateral/contralateral-biased swing, respectively. In addition, the electrophysiological and behavioral findings also revealed that activation of dopamine D2 receptors by quinpirole strengthened KW6002/SCH442416-induced excitation of pallidal activity. Co-application of quinpirole with KW6002 or SCH442416 alleviated biased swing in hemi-parkinsonian rats. Based on the present findings, we concluded that pallidal adenosine A2A receptors may be potentially useful in the treatment of Parkinson's disease.

  12. Insulin receptor binding and protein kinase activity in muscles of trained rats

    International Nuclear Information System (INIS)

    Dohm, G.L.; Sinha, M.K.; Caro, J.F.

    1987-01-01

    Exercise has been shown to increase insulin sensitivity, and muscle is quantitatively the most important tissue of insulin action. Since the first step in insulin action is the binding to a membrane receptor, the authors postulated that exercise training would change insulin receptors in muscle and in this study they have investigated this hypothesis. Female rats initially weighing ∼ 100 g were trained by treadmill running for 2 h/day, 6 days/wk for 4 wk at 25 m/min (0 grade). Insulin receptors from vastus intermedius muscles were solubilized by homogenizing in a buffer containing 1% Triton X-100 and then partially purified by passing the soluble extract over a wheat germ agglutinin column. The 4 wk training regimen resulted in a 65% increase in citrate synthase activity in red vastus lateralis muscle, indicating an adaptation to exercise [ 125 I]. Insulin binding by the partially purified receptor preparations was approximately doubled in muscle of trained rats at all insulin concentrations, suggesting an increase in the number of receptors. Training did not alter insulin receptor structure as evidenced by electrophoretic mobility under reducing and nonreducing conditions. Basal insulin receptor protein kinase activity was higher in trained than untrained animals and this was likely due to the greater number of receptors. However, insulin stimulation of the protein kinase activity was depressed by training. These results demonstrate that endurance training does alter receptor number and function in muscle and these changes may be important in increasing insulin sensitivity after exercise training

  13. Environmental properties related to active galactic nuclei

    Science.gov (United States)

    Manzer, Lianne H.

    There continues to be significant controversy regarding the mechanisms responsible for the initiation of activity in galactic nuclei. It is well understood that the non-thermal energy produced by an AGN is due to accretion onto a supermassive black hole. It has not yet been determined, however, what leads particular galaxies to become active. An accurate exploration into what triggers an AGN demands an analysis of a large sample of galaxies across a diverse set of environments. In this work, we investigate possible environmental influences by carrying out a statistical investigation of galaxy groups. Using the catalogue of Yang et al. (2007), in which groups of galaxies containing between 2 and 20 members with redshifts between 0.01 -- 0.20 were taken from the Sloan Digital Sky Survey, we investigate the fraction of active galactic nuclei (AGN) within these groups and compare it to the sample of isolated galaxies also obtained from Yang et al. (2007). After correcting our spectroscopic data for extinction and underlying stellar absorption, we classify the galaxy sample using relevant emission-line ratios. We propose an alternate method for classifying emission-line galaxies, including AGN, which builds upon standard diagnostic utilities used for optical classification and includes uncertainties. Such classification probabilities offer a more robust and consistent method of investigating the effect of group environments with galaxy type. We find our sample to be a fair representation of the local universe by comparing the luminosity function of our entire data set to that of Blanton et al. (2001), Blanton et al. (2003b), and Montero-Dorta & Prada (2009). The evidence also suggests that the luminosity function of galaxies differs between isolated galaxies and galaxies in groups. We find a significant increase in the fraction of AGNs identified in grouped environments. On the other hand, we find a higher fraction of starforming galaxies within isolated systems. We

  14. Purification of the active C5a receptor from human polymorphonuclear leukocytes as a receptor - G sub i complex

    Energy Technology Data Exchange (ETDEWEB)

    Rollins, T.E.; Siciliano, S.; Kobayashi, S.; Cianciarulo, D.N.; Bonilla-Argudo, V.; Collier, K.; Springer, M.S. (Merck Sharp and Dohme Research Lab., Rahway, NJ (United States))

    1991-02-01

    The authors have isolated, in an active state, the C5a receptor from human polymorphonuclear leukocytes. The purification was achieved in a single step using a C5a affinity column in which the C5a molecule was coupled to the resin through its N terminus. The purified receptor, like the crude solubilized molecule, exhibited a single class of high-affinity binding sites with a K{sub d} of 30 pM. Further, the binding of C5a retained its sensitivity to guanine nucleotides, implying that the purified receptor contained a guanine nucleotide-binding protein (G protein). SDS/PAGE revealed the presence of three polypeptides with molecular masses of 42, 40, and 36 kDa, which were determined to be the C5a-binding subunit and the {alpha} and {beta} subunits of G{sub i}, respectively. The 36- and 40-kDa polypeptides were identified by immunoblotting and by the ability of pertussis toxin to ADP-ribosylate the 40-kDa molecule. These results confirm their earlier hypothesis that the receptor exists as a complex with a G protein in the presence or absence of C5a. The tight coupling between the receptor and G protein should make possible the identification of the G protein(s) involved in the transduction pathways used by C5a to produce its many biological effects.

  15. Purification of the active C5a receptor from human polymorphonuclear leukocytes as a receptor - Gi complex

    International Nuclear Information System (INIS)

    Rollins, T.E.; Siciliano, S.; Kobayashi, S.; Cianciarulo, D.N.; Bonilla-Argudo, V.; Collier, K.; Springer, M.S.

    1991-01-01

    The authors have isolated, in an active state, the C5a receptor from human polymorphonuclear leukocytes. The purification was achieved in a single step using a C5a affinity column in which the C5a molecule was coupled to the resin through its N terminus. The purified receptor, like the crude solubilized molecule, exhibited a single class of high-affinity binding sites with a K d of 30 pM. Further, the binding of C5a retained its sensitivity to guanine nucleotides, implying that the purified receptor contained a guanine nucleotide-binding protein (G protein). SDS/PAGE revealed the presence of three polypeptides with molecular masses of 42, 40, and 36 kDa, which were determined to be the C5a-binding subunit and the α and β subunits of G i , respectively. The 36- and 40-kDa polypeptides were identified by immunoblotting and by the ability of pertussis toxin to ADP-ribosylate the 40-kDa molecule. These results confirm their earlier hypothesis that the receptor exists as a complex with a G protein in the presence or absence of C5a. The tight coupling between the receptor and G protein should make possible the identification of the G protein(s) involved in the transduction pathways used by C5a to produce its many biological effects

  16. Analysis of the epidermal growth factor receptor specific transcriptome: effect of receptor expression level and an activating mutation

    DEFF Research Database (Denmark)

    Pedersen, Mikkel W; Pedersen, Nina; Damstrup, Lars

    2005-01-01

    moderately expressed or overexpressed at an in-itself transforming level. These changes were compared to those induced by the naturally occurring constitutively active variant EGFRvIII. This study provides novel insight on the activities and mechanisms of EGFRvIII and EGFR mediated transformation, as genes...... by interferons. Expression of this module was absent in the EGFRvIII-expressing cell line and the parental cell line. Treatment with the specific EGFR inhibitor AG1478 indicated that the regulations were primary, receptor-mediated events. Furthermore, activation of this module correlated with activation of STAT1...

  17. Confinement of activating receptors at the plasma membrane controls natural killer cell tolerance.

    Science.gov (United States)

    Guia, Sophie; Jaeger, Baptiste N; Piatek, Stefan; Mailfert, Sébastien; Trombik, Tomasz; Fenis, Aurore; Chevrier, Nicolas; Walzer, Thierry; Kerdiles, Yann M; Marguet, Didier; Vivier, Eric; Ugolini, Sophie

    2011-04-05

    Natural killer (NK) cell tolerance to self is partly ensured by major histocompatibility complex (MHC) class I-specific inhibitory receptors on NK cells, which dampen their reactivity when engaged. However, NK cells that do not detect self MHC class I are not autoreactive. We used dynamic fluorescence correlation spectroscopy to show that MHC class I-independent NK cell tolerance in mice was associated with the presence of hyporesponsive NK cells in which both activating and inhibitory receptors were confined in an actin meshwork at the plasma membrane. In contrast, the recognition of self MHC class I by inhibitory receptors "educated" NK cells to become fully reactive, and activating NK cell receptors became dynamically compartmentalized in membrane nanodomains. We propose that the confinement of activating receptors at the plasma membrane is pivotal to ensuring the self-tolerance of NK cells.

  18. Reversal of metabolic disorders by pharmacological activation of bile acid receptors TGR5 and FXR

    Directory of Open Access Journals (Sweden)

    Kavita Jadhav

    2018-03-01

    Full Text Available Objectives: Activation of the bile acid (BA receptors farnesoid X receptor (FXR or G protein-coupled bile acid receptor (GPBAR1; TGR5 improves metabolic homeostasis. In this study, we aim to determine the impact of pharmacological activation of bile acid receptors by INT-767 on reversal of diet-induced metabolic disorders, and the relative contribution of FXR vs. TGR5 to INT-767's effects on metabolic parameters. Methods: Wild-type (WT, Tgr5−/−, Fxr−/−, Apoe−/− and Shp−/− mice were used to investigate whether and how BA receptor activation by INT-767, a semisynthetic agonist for both FXR and TGR5, could reverse diet-induced metabolic disorders. Results: INT-767 reversed HFD-induced obesity dependent on activation of both TGR5 and FXR and also reversed the development of atherosclerosis and non-alcoholic fatty liver disease (NAFLD. Mechanistically, INT-767 improved hypercholesterolemia by activation of FXR and induced thermogenic genes via activation of TGR5 and/or FXR. Furthermore, INT-767 inhibited several lipogenic genes and de novo lipogenesis in the liver via activation of FXR. We identified peroxisome proliferation-activated receptor γ (PPARγ and CCAAT/enhancer-binding protein α (CEBPα as novel FXR-regulated genes. FXR inhibited PPARγ expression by inducing small heterodimer partner (SHP whereas the inhibition of CEBPα by FXR was SHP-independent. Conclusions: BA receptor activation can reverse obesity, NAFLD, and atherosclerosis by specific activation of FXR or TGR5. Our data suggest that, compared to activation of FXR or TGR5 only, dual activation of both FXR and TGR5 is a more attractive strategy for treatment of common metabolic disorders. Keywords: Farnesoid X receptor, TGR5, Atherosclerosis, Obesity, NAFLD

  19. [Functional properties of taste bud cells. Mechanisms of afferent neurotransmission in Type II taste receptor cells].

    Science.gov (United States)

    Romanov, R A

    2013-01-01

    Taste Bud cells are heterogeneous in their morphology and functionality. These cells are responsible for sensing a wide variety of substances and for associating detected compounds with a different taste: bitter, sweet, salty, sour and umami. Today we know that each of the five basic tastes corresponds to distinct cell populations organized into three basic morpho-functional cell types. In addition, some receptor cells of the taste bud demonstrate glia-related functions. In this article we expand on some properties of these three morphological receptor cell types. Main focus is devoted to the Type II cells and unusual mechanism for afferent neurotransmission in these cells. Taste cells of the Type II consist of three populations detecting bitter, sweet and umami tastes, and, thus, evoke a serious scientific interest.

  20. Protease-activated receptor 2 modulates proliferation and invasion of oral squamous cell carcinoma cells.

    Science.gov (United States)

    Al-Eryani, Kamal; Cheng, Jun; Abé, Tatsuya; Maruyama, Satoshi; Yamazaki, Manabu; Babkair, Hamzah; Essa, Ahmed; Saku, Takashi

    2015-07-01

    Based on our previous finding that protease-activated receptor 2 (PAR-2) regulates hemophagocytosis of oral squamous cell carcinoma (SCC) cells, which induces their heme oxygenase 1-dependent keratinization, we have formulated a hypothesis that PAR-2 functions in wider activities of SCC cells. To confirm this hypothesis, we investigated immunohistochemical profiles of PAR-2 in oral SCC tissues and its functional roles in cell proliferation and invasion in SCC cells in culture. The PAR-2 expression modes were determined in 48 surgical tissue specimens of oral SCC. Using oral SCC-derived cell systems, we determined both gene and protein expression levels of PAR-2. SCC cell proliferation and invasive properties were also examined in conditions in which PAR-2 was activated by the synthetic peptide SLIGRL. PAR-2 was immunolocalized in oral SCC and carcinoma in situ cells, especially in those on the periphery of carcinoma cell foci (100% of cases), but not in normal oral epithelia. Its expression at both gene and protein levels was confirmed in 3 oral SCC cell lines including ZK-1. Activation of PAR-2 induced ZK-1 cell proliferation in a dose-dependent manner. PAR-2-activated ZK-1 cells invaded faster than nonactivated ones. The expression of PAR-2 is specific to oral malignancies, and PAR-2 regulates the growth and invasion of oral SCC cells. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. A Molecular Mechanism for Sequential Activation of a G Protein-Coupled Receptor

    DEFF Research Database (Denmark)

    Grundmann, Manuel; Tikhonova, Irina G; Hudson, Brian D

    2016-01-01

    Ligands targeting G protein-coupled receptors (GPCRs) are currently classified as either orthosteric, allosteric, or dualsteric/bitopic. Here, we introduce a new pharmacological concept for GPCR functional modulation: sequential receptor activation. A hallmark feature of this is a stepwise ligand...

  2. The minor binding pocket: a major player in 7TM receptor activation

    DEFF Research Database (Denmark)

    Rosenkilde, Mette Marie; Benned-Jensen, Tau; Frimurer, Thomas M.

    2010-01-01

    residue located in one of two adjacent positions. Here we argue that this minor binding pocket is important for receptor activation. Functional coupling of the receptors seems to be mediated through the hydrogen bond network located between the intracellular segments of these TMs, with the allosteric...... targeted in the development of functionally biased drugs....

  3. PKCζ regulates Notch receptor routing and activity in a Notch signaling-dependent manner

    NARCIS (Netherlands)

    Sjöqvist, M.; Antfolk, D.; Ferraris, S.; Rraklli, V.; Haga, C.; Antila, C.; Mutvei, A.; Imanishi, S.Y.; Holmberg, J.; Jin, S.; Eriksson, J.E.; Lendahl, U.; Sahlgren, C.M.

    Activation of Notch signaling requires intracellular routing of the receptor, but the mechanisms controlling the distinct steps in the routing process is poorly understood. We identify PKCζ as a key regulator of Notch receptor intracellular routing. When PKCζ was inhibited in the developing chick

  4. IMPROVED TUMOR CELL KILLING BY TRAIL REQUIRES SELECTIVE AND HIGH AFFINITY RECEPTOR ACTIVATION

    NARCIS (Netherlands)

    Szegezdi, Eva; van der Sloot, Almer M.; Alessandro, Natoni; Mahalingam, Devalingam; Cool, Robbert H.; Munoz, Ines G.; Montoya, Guillermo; Quax, Wim J.; Luis Serrano, Steven de Jong; Samali, Afshin; Wallach, D; Kovalenko, A; Feldman, M

    2011-01-01

    Apoptosis can be activated by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in a wide range of tumor cells, but not in non-transformed cells. TRAIL interaction with receptors DR4 or DR5 induces apoptosis, whereas DcR1, DcR2 and osteoprotegerin are decoy receptors for TRAIL. TRAIL

  5. Interaction between the p21ras GTPase activating protein and the insulin receptor

    NARCIS (Netherlands)

    Pronk, G.J.; Medema, R.H.; Burgering, B.M.T.; Clark, R.; McCormick, F.; Bos, J.L.

    1992-01-01

    We investigated the involvement of the p21ras-GTPase activating protein (GAP) in insulin-induced signal transduction. In cells overexpressing the insulin receptor, we did not observe association between GAP and the insulin receptor after insulin treatment nor the phosphorylation of GAP on tyrosine

  6. Distinct conformational changes in activated agonist-bound and agonist-free glycine receptor subunits

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Lynch, Joseph W

    2009-01-01

    Ligand binding to Cys-loop receptors produces either global conformational changes that lead to activation or local conformational changes that do not. We found that the fluorescence of a fluorophore tethered to R271C in the extracellular M2 region of the alpha1 glycine receptor increases during ...

  7. Signaling cross-talk between peroxisome proliferator-activated receptor/retinoid X receptor and estrogen receptor through estrogen response elements.

    Science.gov (United States)

    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.

  8. Characterization of ligand binding to melanocortin 4 receptors using fluorescent peptides with improved kinetic properties.

    Science.gov (United States)

    Link, Reet; Veiksina, Santa; Rinken, Ago; Kopanchuk, Sergei

    2017-03-15

    Melanocortin 4 (MC 4 ) receptors are important drug targets as they regulate energy homeostasis, eating behaviour and sexual functions. The ligand binding process to these G protein-coupled receptors is subject to considerable complexity. Different steps in the complex dynamic regulation can be characterized by ligand binding kinetics. Optimization of these kinetic parameters in terms of on-rate and residence time can increase the rapid onset of drug action and reduce off-target effects. Fluorescence anisotropy (FA) is one of the homogeneous fluorescence-based assays that enable continuous online monitoring of ligand binding kinetics. FA has been implemented for the kinetic study of melanocortin MC 4 receptors expressed on budded baculoviruses. However, the slow dissociation of the fluorescently labelled peptide NDP-α-MSH does not enable reaching equilibrium nor enable more in-depth study of the binding mechanisms. To overcome this problem, two novel red-shifted fluorescent ligands were designed. These cyclized heptapeptide derivatives (UTBC101 and UTBC102) exhibited nanomolar affinity toward melanocortin MC 4 receptors but had relatively different kinetic properties. The dissociation half-lives of UTBC101 (τ 1/2 =160min) and UTBC102 (τ 1/2 =7min) were shorter compared to that what was previously reported for Cy3B-NDP-α-MSH (τ 1/2 =224min). The significantly shorter dissociation half-life of UTBC102 enables equilibrium in screening assays, whereas the higher affinity of UTBC101 helps to resolve a wider range of competitor potencies. These two ligands are suitable for further kinetic screening of novel melanocortin MC 4 receptor specific ligands and could complement each other in these studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Effect of propofol on androgen receptor activity in prostate cancer cells.

    Science.gov (United States)

    Tatsumi, Kenichiro; Hirotsu, Akiko; Daijo, Hiroki; Matsuyama, Tomonori; Terada, Naoki; Tanaka, Tomoharu

    2017-08-15

    Androgen receptor is a nuclear receptor and transcription factor activated by androgenic hormones. Androgen receptor activity plays a pivotal role in the development and progression of prostate cancer. Although accumulating evidence suggests that general anesthetics, including opioids, affect cancer cell growth and impact patient prognosis, the effect of those drugs on androgen receptor in prostate cancer is not clear. The purpose of this study was to investigate the effect of the general anesthetic propofol on androgen receptor activity in prostate cancer cells. An androgen-dependent human prostate cancer cell line (LNCaP) was stimulated with dihydrotestosterone (DHT) and exposed to propofol. The induction of androgen receptor target genes was investigated using real-time reverse transcription polymerase chain reaction, and androgen receptor protein levels and localization patterns were analyzed using immunoblotting and immunofluorescence assays. The effect of propofol on the proliferation of LNCaP cells was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Propofol significantly inhibited DHT-induced expression of androgen receptor target genes in a dose- and time-dependent manner, and immunoblotting and immunofluorescence assays indicated that propofol suppressed nuclear levels of androgen receptor proteins. Exposure to propofol for 24h suppressed the proliferation of LNCaP cells, whereas 4h of exposure did not exert significant effects. Together, our results indicate that propofol suppresses nuclear androgen receptor protein levels, and inhibits androgen receptor transcriptional activity and proliferation in LNCaP cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Alternative activation of macrophages and pulmonary fibrosis are modulated by scavenger receptor, macrophage receptor with collagenous structure.

    Science.gov (United States)

    Murthy, Shubha; Larson-Casey, Jennifer L; Ryan, Alan J; He, Chao; Kobzik, Lester; Carter, A Brent

    2015-08-01

    Alternative activation of alveolar macrophages is linked to fibrosis following exposure to asbestos. The scavenger receptor, macrophage receptor with collagenous structure (MARCO), provides innate immune defense against inhaled particles and pathogens; however, a receptor for asbestos has not been identified. We hypothesized that MARCO acts as an initial signaling receptor for asbestos, polarizes macrophages to a profibrotic M2 phenotype, and is required for the development of asbestos-induced fibrosis. Compared with normal subjects, alveolar macrophages isolated from patients with asbestosis express higher amounts of MARCO and have greater profibrotic polarization. Arginase 1 (40-fold) and IL-10 (265-fold) were higher in patients. In vivo, the genetic deletion of MARCO attenuated the profibrotic environment and pulmonary fibrosis in mice exposed to chrysotile. Moreover, alveolar macrophages from MARCO(-/-) mice polarize to an M1 phenotype, whereas wild-type mice have higher Ym1 (>3.0-fold) and nearly 7-fold more active TGF-β1 in bronchoalveolar lavage (BAL) fluid (BALF). Arg(432) and Arg(434) in domain V of MARCO are required for the polarization of macrophages to a profibrotic phenotype as mutation of these residues reduced FIZZ1 expression (17-fold) compared with cells expressing MARCO. These observations demonstrate that a macrophage membrane protein regulates the fibrotic response to lung injury and suggest a novel target for therapeutic intervention. © FASEB.

  11. Novel role for proteinase-activated receptor 2 (PAR2) in membrane trafficking of proteinase-activated receptor 4 (PAR4).

    Science.gov (United States)

    Cunningham, Margaret R; McIntosh, Kathryn A; Pediani, John D; Robben, Joris; Cooke, Alexandra E; Nilsson, Mary; Gould, Gwyn W; Mundell, Stuart; Milligan, Graeme; Plevin, Robin

    2012-05-11

    Proteinase-activated receptors 4 (PAR(4)) is a class A G protein-coupled receptor (GPCR) recognized through the ability of serine proteases such as thrombin and trypsin to mediate receptor activation. Due to the irreversible nature of activation, a fresh supply of receptor is required to be mobilized to the cell surface for responsiveness to agonist to be sustained. Unlike other PAR subtypes, the mechanisms regulating receptor trafficking of PAR(4) remain unknown. Here, we report novel features of the intracellular trafficking of PAR(4) to the plasma membrane. PAR(4) was poorly expressed at the plasma membrane and largely retained in the endoplasmic reticulum (ER) in a complex with the COPI protein subunit β-COP1. Analysis of the PAR(4) protein sequence identified an arginine-based (RXR) ER retention sequence located within intracellular loop-2 (R(183)AR → A(183)AA), mutation of which allowed efficient membrane delivery of PAR(4). Interestingly, co-expression with PAR(2) facilitated plasma membrane delivery of PAR(4), an effect produced through disruption of β-COP1 binding and facilitation of interaction with the chaperone protein 14-3-3ζ. Intermolecular FRET studies confirmed heterodimerization between PAR(2) and PAR(4). PAR(2) also enhanced glycosylation of PAR(4) and activation of PAR(4) signaling. Our results identify a novel regulatory role for PAR(2) in the anterograde traffic of PAR(4). PAR(2) was shown to both facilitate and abrogate protein interactions with PAR(4), impacting upon receptor localization and cell signal transduction. This work is likely to impact markedly upon the understanding of the receptor pharmacology of PAR(4) in normal physiology and disease.

  12. Transcriptional activation by the thyroid hormone receptor through ligand-dependent receptor recruitment and chromatin remodelling

    DEFF Research Database (Denmark)

    Grøntved, Lars; Waterfall, Joshua J; Kim, Dong Wook

    2015-01-01

    A bimodal switch model is widely used to describe transcriptional regulation by the thyroid hormone receptor (TR). In this model, the unliganded TR forms stable, chromatin-bound complexes with transcriptional co-repressors to repress transcription. Binding of hormone dissociates co...

  13. The angiotensin II type 1 receptor antagonist Losartan binds and activates bradykinin B2 receptor signaling

    DEFF Research Database (Denmark)

    Bonde, Marie Mi; Olsen, Kristine Boisen; Erikstrup, Niels

    2011-01-01

    The angiotensin II type 1 receptor (AT1R) blocker (ARB) Losartan has cardioprotective effects during ischemia-reperfusion injury and inhibits reperfusion arrhythmias -effects that go beyond the benefits of lowering blood pressure. The renin-angiotensin and kallikrein-kinin systems are intricately...

  14. DMPD: Proximal effects of Toll-like receptor activation in dendritic cells. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 17142025 Proximal effects of Toll-like receptor activation in dendritic cells. Watt...) (.svg) (.html) (.csml) Show Proximal effects of Toll-like receptor activation in dendritic cells. PubmedID... 17142025 Title Proximal effects of Toll-like receptor activation in dendritic ce

  15. Recurrent exposure to nicotine differentiates human bronchial epithelial cells via epidermal growth factor receptor activation

    International Nuclear Information System (INIS)

    Martinez-Garcia, Eva; Irigoyen, Marta; Anso, Elena; Martinez-Irujo, Juan Jose; Rouzaut, Ana

    2008-01-01

    Cigarette smoking is the major preventable cause of lung cancer in developed countries. Nicotine (3-(1-methyl-2-pyrrolidinyl)-pyridine) is one of the major alkaloids present in tobacco. Besides its addictive properties, its effects have been described in panoply of cell types. In fact, recent studies have shown that nicotine behaves as a tumor promoter in transformed epithelial cells. This research focuses on the effects of acute repetitive nicotine exposure on normal human bronchial epithelial cells (NHBE cells). Here we show that treatment of NHBE cells with recurrent doses of nicotine up to 500 μM triggered cell differentiation towards a neuronal-like phenotype: cells emitted filopodia and expressed neuronal markers such as neuronal cell adhesion molecule, neurofilament-M and the transcription factors neuronal N and Pax-3. We also demonstrate that nicotine treatment induced NF-kB translocation to the nucleus, phosphorylation of the epidermal growth factor receptor (EGFR), and accumulation of heparin binding-EGF in the extracellular medium. Moreover, addition of AG1478, an inhibitor of EGFR tyrosine phosphorylation, or cetuximab, a monoclonal antibody that precludes ligand binding to the same receptor, prevented cell differentiation by nicotine. Lastly, we show that differentiated cells increased their adhesion to the extracellular matrix and their protease activity. Given that several lung pathologies are strongly related to tobacco consumption, these results may help to better understand the damaging consequences of nicotine exposure

  16. Modulation of the constitutive activity of the ghrelin receptor by use of pharmacological tools and mutagenesis

    DEFF Research Database (Denmark)

    Mokrosinski, Jacek; Holst, Birgitte

    2010-01-01

    Ghrelin and its receptor are important regulators of metabolic functions, including appetite, energy expenditure, fat accumulation, and growth hormone (GH) secretion. The ghrelin receptor is characterized by an ability to signal even without any ligand present with approximately 50......% of the maximally ghrelin-induced efficacy-a feature that may have important physiological implications. The high basal signaling can be modulated either by administration of specific ligands or by engineering of mutations in the receptor structure. [D-Arg(1), D-Phe(5), D-Trp(7,9), Leu(11)]-substance P...... was the first inverse agonist to be identified for the ghrelin receptor, and this peptide has been used as a starting point for identification of the structural requirements for inverse agonist properties in the ligand. The receptor binding core motif was identified as D-Trp-Phe-D-Trp-Leu-Leu, and elongation...

  17. In vitro assessment of the agonist properties of the novel 5-HT1A receptor ligand, CUMI-101 (MMP), in rat brain tissue

    International Nuclear Information System (INIS)

    Hendry, Nicola; Christie, Isabel; Rabiner, Eugenii Alfredovich; Laruelle, Marc; Watson, Jeannette

    2011-01-01

    Introduction: Development of agonist positron emission tomography (PET) radioligands for the 5-HT neurotransmitter system is an important target to enable the understanding of human 5-HT function in vivo. [ 11 C]CUMI-101, proposed as the first 5-HT 1A receptor agonist PET ligand, has been reported to behave as a potent 5-HT 1A agonist in a cellular system stably expressing human recombinant 5-HT 1A receptors. In this study, we investigate the agonist properties of CUMI-101 in rat brain tissue. Methods: [ 35 S]-GTPγS binding studies were used to determine receptor function in HEK (human embryonic kidney) 293 cells transfected with human recombinant 5-HT 1A receptors and in rat cortex and rat hippocampal tissue, following administration of CUMI-101 and standard 5-HT1A antagonists (5-HT, 5-CT and 8-OH-DPAT). Results: CUMI-101 behaved as an agonist at human recombinant 5-HT 1A receptors (pEC 50 9.2). However, CUMI-101 did not show agonist activity in either rat cortex or hippocampus at concentrations up to 10 μM. In these tissues, CUMI-behaved as an antagonist with pK B s of 9.2 and 9.3, respectively. Conclusions: Our studies demonstrate that as opposed to its behavior in human recombinant system, in rat brain tissue CUMI-101 behaves as a potent 5-HT 1A receptor antagonist.

  18. Activation of peroxisome proliferator-activated receptor-α enhances fatty acid oxidation in human adipocytes

    International Nuclear Information System (INIS)

    Lee, Joo-Young; Hashizaki, Hikari; Goto, Tsuyoshi; Sakamoto, Tomoya; Takahashi, Nobuyuki; Kawada, Teruo

    2011-01-01

    Highlights: → PPARα activation increased mRNA expression levels of adipocyte differentiation marker genes and GPDH activity in human adipocytes. → PPARα activation also increased insulin-dependent glucose uptake in human adipocytes. → PPARα activation did not affect lipid accumulation in human adipocytes. → PPARα activation increased fatty acid oxidation through induction of fatty acid oxidation-related genes in human adipocytes. -- Abstract: Peroxisome proliferator-activated receptor-α (PPARα) is a key regulator for maintaining whole-body energy balance. However, the physiological functions of PPARα in adipocytes have been unclarified. We examined the functions of PPARα using human multipotent adipose tissue-derived stem cells as a human adipocyte model. Activation of PPARα by GW7647, a potent PPARα agonist, increased the mRNA expression levels of adipocyte differentiation marker genes such as PPARγ, adipocyte-specific fatty acid-binding protein, and lipoprotein lipase and increased both GPDH activity and insulin-dependent glucose uptake level. The findings indicate that PPARα activation stimulates adipocyte differentiation. However, lipid accumulation was not changed, which is usually observed when PPARγ is activated. On the other hand, PPARα activation by GW7647 treatment induced the mRNA expression of fatty acid oxidation-related genes such as CPT-1B and AOX in a PPARα-dependent manner. Moreover, PPARα activation increased the production of CO 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 PPARα stimulates both adipocyte differentiation and fatty acid oxidation in human adipocytes, suggesting that PPARα agonists could improve insulin resistance without lipid accumulation in adipocytes. The expected effects of PPARα activation are very valuable for managing diabetic conditions accompanied by obesity, because

  19. GABA-B receptor activation and conflict behavior

    International Nuclear Information System (INIS)

    Ketelaars, C.E.J.; Bollen, E.L.; Rigter, H.; Bruinvels, J.

    1988-01-01

    Baclofen and oxazepam enhance extinction of conflict behavior in the Geller-Seifter test while baclofen and diazepam release punished behavior in Vogel's conflict test. In order to investigate the possibility that the effect of the selective GABA-B receptor agonist baclofen is mediated indirectly via the GABA-A/benzodiazepine receptor complex, the effect of pretreatment of rats with baclofen on [ 3 H]-diazepam binding to washed and unwashed cortical and cerebellar membranes of rats has been studied. Baclofen pretreatment increase Bmax in washed cerebellar membranes when bicuculline was present in the incubation mixture. No effect was seen in cortical membranes. The present results render it unlikely that the effect of baclofen on extinction of conflict behavior and punished drinking is mediated via the GABA-A/benzodiazepine receptor complex. 50 references, 1 figure, 4 tables

  20. Physical activity status, but not age, influences inflammatory biomarkers and toll-like receptor 4.

    Science.gov (United States)

    McFarlin, Brian K; Flynn, Michael G; Campbell, Wayne W; Craig, Bruce A; Robinson, J Paul; Stewart, Laura K; Timmerman, Kyle L; Coen, Paul M

    2006-04-01

    Chronic inflammation has been implicated in the development of cardiovascular disease, diabetes mellitus, cachexia, and osteoporosis. Regular physical activity has been purported to possess "anti-inflammatory" properties which may limit chronic inflammation. Recently, we hypothesized that toll-like receptor 4 (TLR4) may play a role in activity-induced modulation of inflammation. Therefore, the purpose of this study was to determine the association between age, physical activity status, biomarkers of inflammation, and TLR4. Male and female participants (n = 84) were recruited to fill one of the following groups: young (18-30 years), active; young, inactive; old (60-80 years), active; or old, inactive. To assess physical activity status, participants completed a Paffenbarger Physical Activity Questionnaire and a modified Balke submaximal treadmill test. After grouping and screening, participants were given a standard mixed diet to consume 24 hours prior to arriving at the laboratory. Participants were instructed to consume all food by 10 pm the night prior to blood sampling (8-hour fast). Following 30 minutes of seated rest in a quiet room, venous blood samples were collected. Lipopolysaccharide-stimulated inflammatory cytokine production and plasma high-sensitivity C-reactive protein (hsCRP) were determined by enzyme-linked immunosorbent assay, and TLR4 expression was determined by flow cytometry. Lipopolysaccharide-stimulated interleukin-6, interleukin-1beta, and tumor necrosis factor-alpha production, TLR4 expression, and hsCRP were significantly lower in active compared to inactive participants (p work from our laboratory, suggests that TLR4 may play a role in regulating the link between inflammatory cytokine production and a physically active lifestyle.

  1. Modulation in selectivity and allosteric properties of small-molecule ligands for CC-chemokine receptors

    DEFF Research Database (Denmark)

    Thiele, Stefanie; Malmgaard-Clausen, Mikkel; Engel-Andreasen, Jens

    2012-01-01

    Among 18 human chemokine receptors, CCR1, CCR4, CCR5, and CCR8 were activated by metal ion Zn(II) or Cu(II) in complex with 2,2'-bipyridine or 1,10-phenanthroline with similar potencies (EC(50) from 3.9 to 172 μM). Besides being agonists, they acted as selective allosteric enhancers of CCL3. Thes...

  2. The insulin and IGF1 receptor kinase domains are functional dimers in the activated state

    Science.gov (United States)

    Cabail, M. Zulema; Li, Shiqing; Lemmon, Eric; Bowen, Mark E.; Hubbard, Stevan R.; Miller, W. Todd

    2015-03-01

    The insulin receptor (IR) and insulin-like growth factor-1 receptor (IGF1R) are highly related receptor tyrosine kinases with a disulfide-linked homodimeric architecture. Ligand binding to the receptor ectodomain triggers tyrosine autophosphorylation of the cytoplasmic domains, which stimulates catalytic activity and creates recruitment sites for downstream signalling proteins. Whether the two phosphorylated tyrosine kinase domains within the receptor dimer function independently or cooperatively to phosphorylate protein substrates is not known. Here we provide crystallographic, biophysical and biochemical evidence demonstrating that the phosphorylated kinase domains of IR and IGF1R form a specific dimeric arrangement involving an exchange of the juxtamembrane region proximal to the kinase domain. In this dimer, the active position of α-helix C in the kinase N lobe is stabilized, which promotes downstream substrate phosphorylation. These studies afford a novel strategy for the design of small-molecule IR agonists as potential therapeutic agents for type 2 diabetes.

  3. Novel time-dependent vascular actions of {delta}{sup 9}-tetrahydrocannabinol mediated by peroxisome proliferator-activated receptor gamma

    Energy Technology Data Exchange (ETDEWEB)

    O' Sullivan, Saoirse E [School of Biomedical Sciences, E Floor, Queen' s Medical Centre, University of Nottingham, Nottingham NG7 2UH (United Kingdom); Tarling, Elizabeth J [School of Biomedical Sciences, E Floor, Queen' s Medical Centre, University of Nottingham, Nottingham NG7 2UH (United Kingdom); Bennett, Andrew J [School of Biomedical Sciences, E Floor, Queen' s Medical Centre, University of Nottingham, Nottingham NG7 2UH (United Kingdom); Kendall, David A [School of Biomedical Sciences, E Floor, Queen' s Medical Centre, University of Nottingham, Nottingham NG7 2UH (United Kingdom); Randall, Michael D [School of Biomedical Sciences, E Floor, Queen' s Medical Centre, University of Nottingham, Nottingham NG7 2UH (United Kingdom)

    2005-11-25

    Cannabinoids have widespread effects on the cardiovascular system, only some of which are mediated via G-protein-coupled cell surface receptors. The active ingredient of cannabis, {delta}{sup 9}-tetrahydrocannabinol (THC), causes acute vasorelaxation in various arteries. Here we show for the first time that THC also causes slowly developing vasorelaxation through activation of peroxisome proliferator-activated receptors gamma (PPAR{gamma}). In vitro, THC (10 {mu}M) caused time-dependent vasorelaxation of rat isolated arteries. Time-dependent vasorelaxation to THC was similar to that produced by the PPAR{gamma} agonist rosiglitazone and was inhibited by the PPAR{gamma} antagonist GW9662 (1 {mu}M), but not the cannabinoid CB{sub 1} receptor antagonist AM251 (1 {mu}M). Time-dependent vasorelaxation to THC requires an intact endothelium, nitric oxide, production of hydrogen peroxide, and de novo protein synthesis. In transactivation assays in cultured HEK293 cells, THC-activated PPAR{gamma}, transiently expressed in combination with retinoid X receptor {alpha} and a luciferase reporter gene, in a concentration-dependent manner (100 nM-10 {mu}M). In vitro incubation with THC (1 or 10 {mu}M, 8 days) stimulated adipocyte differentiation in cultured 3T3L1 cells, a well-accepted property of PPAR{gamma} ligands. The present results provide strong evidence that THC is a PPAR{gamma} ligand, stimulation of which causes time-dependent vasorelaxation, implying some of the pleiotropic effects of cannabis may be mediated by nuclear receptors.

  4. The dopamine D2 receptor can directly recruit and activate GRK2 without G protein activation.

    Science.gov (United States)

    Pack, Thomas F; Orlen, Margo I; Ray, Caroline; Peterson, Sean M; Caron, Marc G

    2018-04-20

    The dopamine D2 receptor (D2R) is a G protein-coupled receptor (GPCR) that is critical for many central nervous system functions. The D2R carries out these functions by signaling through two transducers: G proteins and β-arrestins (βarrs). Selectively engaging either the G protein or βarr pathway may be a way to improve drugs targeting GPCRs. The current model of GPCR signal transduction posits a chain of events where G protein activation ultimately leads to βarr recruitment. GPCR kinases (GRKs), which are regulated by G proteins and whose kinase action facilitates βarr recruitment, bridge these pathways. Therefore, βarr recruitment appears to be intimately tied to G protein activation via GRKs. Here we sought to understand how GRK2 action at the D2R would be disrupted when G protein activation is eliminated and the effect of this on βarr recruitment. We used two recently developed biased D2R mutants that can preferentially interact either with G proteins or βarrs as well as a βarr-biased D2R ligand, UNC9994. With these functionally selective tools, we investigated the mechanism whereby the βarr-preferring D2R achieves βarr pathway activation in the complete absence of G protein activation. We describe how direct, G protein-independent recruitment of GRK2 drives interactions at the βarr-preferring D2R and also contributes to βarr recruitment at the WT D2R. Additionally, we found an additive interaction between the βarr-preferring D2R mutant and UNC9994. These results reveal that the D2R can directly recruit GRK2 without G protein activation and that this mechanism may have relevance to achieving βarr-biased signaling. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Glutarimides: Biological activity, general synthetic methods and physicochemical properties

    Directory of Open Access Journals (Sweden)

    Popović-Đorđević Jelena B.

    2015-01-01

    Full Text Available Glutarimides, 2,6-dioxopiperidines are compounds that rarely occur in natural sources, but so far isolated ones exert widespread pharmacological activities, which makes them valuable as potential pharmacotherapeutics. Glutarimides act as androgen receptor antagonists, anti-inflammatory, anxiolytics, antibacterials, and tumor suppressing agents. Some synthetic glutarimide derivatives are already in use as immunosuppressive and sedative (e.g., thalidomide or anxiolytics (buspirone drugs. The wide applicability of this class of compounds, justify the interest of scientists to explore new pathways for its syntheses. General methods for synthesis of six-membered imide ring, are presented in this paper. These methods include: a reaction of dicarboxylic acids with ammonia or primary amine, b reactions of cyclization: amido-acids, diamides, dinitriles, nitrilo-acids, amido-nitriles, amido-esters, amidoacyl-chlorides or diacyl-chlorides, c adition of carbon-monoxide on a,b-unsaturated amides, d oxidation reactions, e Michael adition of active methylen compounds on methacrylamide or conjugated amides. Some of the described methods are used for closing glutarimide ring in syntheses of farmacological active compounds sesbanimide and aldose reductase inhibitors (ARI. Analyses of the geometry, as well as, the spectroscopic analyses (NMR and FT-IR of some glutarimides are presented because of their broad spectrum of pharmacological activity. To elucidate structures of glutarimides, geometrical parameters of newly synthesized tert-pentyl-1-benzyl-4-methyl-glutarimide-3-carboxylate (PBMG are analyzed and compared with the experimental data from X-ray analysis for glutarimide. Moreover, molecular electrostatic potential (MEP surface which is plotted over the optimized geometry to elucidate the reactivity of PBMG molecule is analyzed. The electronic properties of glutarimide derivatives are explained on the example of thalidomide. The Frontier Molecular Orbital

  6. GABAA receptor activity modulating piperine analogs: In vitro metabolic stability, metabolite identification, CYP450 reaction phenotyping, and protein binding.

    Science.gov (United States)

    Zabela, Volha; Hettich, Timm; Schlotterbeck, Götz; Wimmer, Laurin; Mihovilovic, Marko D; Guillet, Fabrice; Bouaita, Belkacem; Shevchenko, Bénédicte; Hamburger, Matthias; Oufir, Mouhssin

    2018-01-01

    In a screening of natural products for allosteric modulators of GABA A receptors (γ-aminobutyric acid type A receptor), piperine was identified as a compound targeting a benzodiazepine-independent binding site. Given that piperine is also an activator of TRPV1 (transient receptor potential vanilloid type 1) receptors involved in pain signaling and thermoregulation, a series of piperine analogs were prepared in several cycles of structural optimization, with the aim of separating GABA A and TRPV1 activating properties. We here investigated the metabolism of piperine and selected analogs in view of further cycles of lead optimization. Metabolic stability of the compounds was evaluated by incubation with pooled human liver microsomes, and metabolites were analyzed by UHPLC-Q-TOF-MS. CYP450 isoenzymes involved in metabolism of compounds were identified by reaction phenotyping with Silensomes™. Unbound fraction in whole blood was determined by rapid equilibrium dialysis. Piperine was the metabolically most stable compound. Aliphatic hydroxylation, and N- and O-dealkylation were the major routes of oxidative metabolism. Piperine was exclusively metabolized by CYP1A2, whereas CYP2C9 contributed significantly in the oxidative metabolism of all analogs. Extensive binding to blood constituents was observed for all compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Synthesis and characterization of a series of diarylguanidines that are noncompetitive N-methyl-D-aspartate receptor antagonists with neuroprotective properties

    International Nuclear Information System (INIS)

    Keana, J.F.W.; McBurney, R.N.; Scherz, M.W.

    1989-01-01

    Four diarylguanidine derivatives were synthesized. These compounds were found to displace, at submicromolar concentrations, 3 H-labeled 1-[1-(2-thienyl)cyclohexyl]piperidine and (+)-[ 3 H]MK-801 from phencyclidine receptors in brain membrane preparations. In electrophysiological experiments the diarylguanidines blocked N-methyl-D-aspartate (NMDA)-activated ion channels. These dairylguanidines also protected rat hippocampal neurons in vitro from glutamate-induced cell death. The results show that some diarylguanidines are noncompetitive antagonists of NMDA receptor-mediated responses and have the neuroprotective property that is commonly associated with blockers of the NMDA receptor-gated cation channel. Diarylguanidines are structurally unrelated to known blockers of NMDA channels and, therefore, represent a new compound series for the development of neuroprotective agents with therapeutic value in patients suffering from stroke, from brain or spinal cord trauma, from hypoglycemia, and possibly from brain ischemia due to heart attack

  8. Characterization of the single transmembrane domain of human receptor activity-modifying protein 3 in adrenomedullin receptor internalization

    International Nuclear Information System (INIS)

    Kuwasako, Kenji; Kitamura, Kazuo; Nagata, Sayaka; Nozaki, Naomi; Kato, Johji

    2012-01-01

    Highlights: ► RAMP3 mediates CLR internalization much less effectively than does RAMP2. ► The RAMP3 TMD participates in the negative regulation of CLR/RAMP3 internalization. ► A new strategy of promoting internalization and resensitization of the receptor was found. -- Abstract: Two receptor activity-modifying proteins (RAMP2 and RAMP3) enable calcitonin receptor-like receptor (CLR) to function as two heterodimeric receptors (CLR/RAMP2 and CLR/RAMP3) for adrenomedullin (AM), a potent cardiovascular protective peptide. Following AM stimulation, both receptors undergo rapid internalization through a clathrin-dependent pathway, after which CLR/RAMP3, but not CLR/RAMP2, can be recycled to the cell surface for resensitization. However, human (h)RAMP3 mediates CLR internalization much less efficiently than does hRAMP2. Therefore, the molecular basis of the single transmembrane domain (TMD) and the intracellular domain of hRAMP3 during AM receptor internalization was investigated by transiently transfecting various RAMP chimeras and mutants into HEK-293 cells stably expressing hCLR. Flow cytometric analysis revealed that substituting the RAMP3 TMD with that of RAMP2 markedly enhanced AM-induced internalization of CLR. However, this replacement did not enhance the cell surface expression of CLR, [ 125 I]AM binding affinity or AM-induced cAMP response. More detailed analyses showed that substituting the Thr 130 –Val 131 sequence in the RAMP3 TMD with the corresponding sequence (Ile 157 –Pro 158 ) from RAMP2 significantly enhanced AM-mediated CLR internalization. In contrast, substituting the RAMP3 target sequence with Ala 130 –Ala 131 did not significantly affect CLR internalization. Thus, the RAMP3 TMD participates in the negative regulation of CLR/RAMP3 internalization, and the aforementioned introduction of the Ile–Pro sequence into the RAMP3 TMD may be a strategy for promoting receptor internalization/resensitization.

  9. The Role of Stat3 Activation in Androgen Receptor Signaling and Prostate Cancer

    National Research Council Canada - National Science Library

    Gao, Allen C

    2006-01-01

    .... The experiments proposed in this application are based upon the hypothesis that Stat3 activation alters androgen receptor signaling pathways which in turn results in the loss of growth control in prostate cancer cells...

  10. The Role of Stat3 Activation in Androgen Receptor Signaling and Prostate Cancer

    National Research Council Canada - National Science Library

    Gao, Allen

    2004-01-01

    .... The experiments proposed in this application are based upon the hypothesis that stat3 activation alters androgen receptor signaling pathways, that in turn results in the loss of growth control in prostate cancer cells...

  11. The Role of Stat3 Activation in Androgen Receptor Signaling and Prostate Cancer

    National Research Council Canada - National Science Library

    Gao, Allen

    2002-01-01

    .... The experiments proposed in this application are based upon the hypothesis that Stat3 activation alters androgen receptor signaling pathways, that in turn results in the loss of growth control in prostate cancer cells...

  12. The Role of Stat3 Activation in Androgen Receptor Signaling and Prostate Cancer

    National Research Council Canada - National Science Library

    Gao, Allen C

    2005-01-01

    .... The experiments proposed in this application are based upon the hypothesis that Stat3 activation alters androgen receptor signaling pathways, that in turn results in the loss of growth control in prostate cancer cells...

  13. The Role of Stat3 Activation in Androgen Receptor Signaling and Prostate Cancer

    National Research Council Canada - National Science Library

    Gao, Allen

    2003-01-01

    .... The experiments proposed in this application are based upon the hypothesis that Stat3 activation alters androgen receptor signaling pathways, that in turn results in the loss of growth control in prostate cancer cells...

  14. Chronic regulation of colonic epithelial secretory function by activation of G protein-coupled receptors.

    LENUS (Irish Health Repository)

    Toumi, F

    2011-02-01

    Enteric neurotransmitters that act at G protein-coupled receptors (GPCRs) are well known to acutely promote epithelial Cl(-) and fluid secretion. Here we examined if acute GPCR activation might have more long-term consequences for epithelial secretory function.

  15. Phorbol ester-induced serine phosphorylation of the insulin receptor decreases its tyrosine kinase activity.

    Science.gov (United States)

    Takayama, S; White, M F; Kahn, C R

    1988-03-05

    The effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) on the function of the insulin receptor was examined in intact hepatoma cells (Fao) and in solubilized extracts purified by wheat germ agglutinin chromatography. Incubation of ortho[32P]phosphate-labeled Fao cells with TPA increased the phosphorylation of the insulin receptor 2-fold after 30 min. Analysis of tryptic phosphopeptides from the beta-subunit of the receptor by reverse-phase high performance liquid chromatography and determination of their phosphoamino acid composition suggested that TPA predominantly stimulated phosphorylation of serine residues in a single tryptic peptide. Incubation of the Fao cells with insulin (100 nM) for 1 min stimulated 4-fold the phosphorylation of the beta-subunit of the insulin receptor. Prior treatment of the cells with TPA inhibited the insulin-stimulated tyrosine phosphorylation by 50%. The receptors extracted with Triton X-100 from TPA-treated Fao cells and purified on immobilized wheat germ agglutinin retained the alteration in kinase activity and exhibited a 50% decrease in insulin-stimulated tyrosine autophosphorylation and phosphotransferase activity toward exogenous substrates. This was due primarily to a decrease in the Vmax for these reactions. TPA treatment also decreased the Km of the insulin receptor for ATP. Incubation of the insulin receptor purified from TPA-treated cells with alkaline phosphatase decreased the phosphate content of the beta-subunit to the control level and reversed the inhibition, suggesting that the serine phosphorylation of the beta-subunit was responsible for the decreased tyrosine kinase activity. Our results support the notion that the insulin receptor is a substrate for protein kinase C in the Fao cell and that the increase in serine phosphorylation of the beta-subunit of the receptor produced by TPA treatment inhibited tyrosine kinase activity in vivo and in vitro. These data suggest that protein kinase C may regulate the function

  16. Bovine cumulus-granulosa cells contain biologically active retinoid receptors that can respond to retinoic acid

    Directory of Open Access Journals (Sweden)

    Malayer Jerry

    2003-11-01

    Full Text Available Abstract Retinoids, a class of compounds that include retinol and its metabolite, retinoic acid, are absolutely essential for ovarian steroid production, oocyte maturation, and early embryogenesis. Previous studies have detected high concentrations of retinol in bovine large follicles. Further, administration of retinol in vivo and supplementation of retinoic acid during in vitro maturation results in enhanced embryonic development. In the present study, we hypothesized that retinoids administered either in vivo previously or in vitro can exert receptor-mediated effects in cumulus-granulosa cells. Total RNA extracted from in vitro cultured cumulus-granulosa cells was subjected to reverse transcription polymerase chain reaction (RT-PCR and mRNA expression for retinol binding protein (RBP, retinoic acid receptor alpha (RARalpha, retinoic acid receptor beta (RARbeta, retinoic acid receptor gamma (RARgamma, retinoid X receptor alpha (RXRalpha, retinoid X receptor beta (RXRbeta, retinaldehyde dehydrogenase-2 (RALDH-2, and peroxisome proliferator activated receptor gamma (PPARgamma. Transcripts were detected for RBP, RARalpha, RARgamma, RXRalpha, RXRbeta, RALDH-2, and PPARgamma. Expression of RARbeta was not detected in cumulus-granulosa cells. Using western blotting, immunoreactive RARalpha, and RXRbeta protein was also detected in bovine cumulus-granulosa cells. The biological activity of these endogenous retinoid receptors was tested using a transient reporter assay using the pAAV-MCS-betaRARE-Luc vector. Addition of 0.5 and 1 micro molar all-trans retinoic acid significantly (P trans retinol stimulated a mild increase in reporter activity, however, the increase was not statistically significant. Based on these results we conclude that cumulus cells contain endogenously active retinoid receptors and may also be competent to synthesize retinoic acid using the precursor, retinol. These results also indirectly provide evidence that retinoids

  17. Differential Requirement of the Extracellular Domain in Activation of Class B G Protein-coupled Receptors.

    Science.gov (United States)

    Zhao, Li-Hua; Yin, Yanting; Yang, Dehua; Liu, Bo; Hou, Li; Wang, Xiaoxi; Pal, Kuntal; Jiang, Yi; Feng, Yang; Cai, Xiaoqing; Dai, Antao; Liu, Mingyao; Wang, Ming-Wei; Melcher, Karsten; Xu, H Eric

    2016-07-15

    G protein-coupled receptors (GPCRs) from the secretin-like (class B) family are key players in hormonal homeostasis and are important drug targets for the treatment of metabolic disorders and neuronal diseases. They consist of a large N-terminal extracellular domain (ECD) and a transmembrane domain (TMD) with the GPCR signature of seven transmembrane helices. Class B GPCRs are activated by peptide hormones with their C termini bound to the receptor ECD and their N termini bound to the TMD. It is thought that the ECD functions as an affinity trap to bind and localize the hormone to the receptor. This in turn would allow the hormone N terminus to insert into the TMD and induce conformational changes of the TMD to activate downstream signaling. In contrast to this prevailing model, we demonstrate that human class B GPCRs vary widely in their requirement of the ECD for activation. In one group, represented by corticotrophin-releasing factor receptor 1 (CRF1R), parathyroid hormone receptor (PTH1R), and pituitary adenylate cyclase activating polypeptide type 1 receptor (PAC1R), the ECD requirement for high affinity hormone binding can be bypassed by induced proximity and mass action effects, whereas in the other group, represented by glucagon receptor (GCGR) and glucagon-like peptide-1 receptor (GLP-1R), the ECD is required for signaling even when the hormone is covalently linked to the TMD. Furthermore, the activation of GLP-1R by small molecules that interact with the intracellular side of the receptor is dependent on the presence of its ECD, suggesting a direct role of the ECD in GLP-1R activation. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. EPO-independent functional EPO receptor in breast cancer enhances estrogen receptor activity and promotes cell proliferation

    International Nuclear Information System (INIS)

    Reinbothe, Susann; Larsson, Anna-Maria; Vaapil, Marica; Wigerup, Caroline; Sun, Jianmin; Jögi, Annika; Neumann, Drorit; Rönnstrand, Lars; Påhlman, Sven

    2014-01-01

    Highlights: • New anti-human EPOR antibody confirms full-length EPOR expression in breast cancer cells. • Proliferation of breast cancer cells is not affected by rhEPO treatment in vitro. • EPOR knockdown impairs proliferation of ERa positive breast cancer cells. • EPOR knockdown reduces AKT phosphorylation and ERa activity. - Abstract: The main function of Erythropoietin (EPO) and its receptor (EPOR) is the stimulation of erythropoiesis. Recombinant human EPO (rhEPO) is therefore used to treat anemia in cancer patients. However, clinical trials have indicated that rhEPO treatment might promote tumor progression and has a negative effect on patient survival. In addition, EPOR expression has been detected in several cancer forms. Using a newly produced anti-EPOR antibody that reliably detects the full-length isoform of the EPOR we show that breast cancer tissue and cells express the EPOR protein. rhEPO stimulation of cultured EPOR expressing breast cancer cells did not result in increased proliferation, overt activation of EPOR (receptor phosphorylation) or a consistent activation of canonical EPOR signaling pathway mediators such as JAK2, STAT3, STAT5, or AKT. However, EPOR knockdown experiments suggested functional EPO receptors in estrogen receptor positive (ERα + ) breast cancer cells, as reduced EPOR expression resulted in decreased proliferation. This effect on proliferation was not seen in ERα negative cells. EPOR knockdown decreased ERα activity further supports a mechanism by which EPOR affects proliferation via ERα-mediated mechanisms. We show that EPOR protein is expressed in breast cancer cells, where it appears to promote proliferation by an EPO-independent mechanism in ERα expressing breast cancer cells

  19. EPO-independent functional EPO receptor in breast cancer enhances estrogen receptor activity and promotes cell proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Reinbothe, Susann; Larsson, Anna-Maria; Vaapil, Marica; Wigerup, Caroline [Department of Laboratory Medicine, Translational Cancer Research, Medicon Village, Lund University, SE-223 81 Lund (Sweden); CREATE Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv (Israel); Sun, Jianmin [Department of Laboratory Medicine, Translational Cancer Research, Medicon Village, Lund University, SE-223 81 Lund (Sweden); Jögi, Annika [Department of Laboratory Medicine, Translational Cancer Research, Medicon Village, Lund University, SE-223 81 Lund (Sweden); CREATE Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv (Israel); Neumann, Drorit [Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv (Israel); Rönnstrand, Lars [Department of Laboratory Medicine, Translational Cancer Research, Medicon Village, Lund University, SE-223 81 Lund (Sweden); Påhlman, Sven, E-mail: sven.pahlman@med.lu.se [Department of Laboratory Medicine, Translational Cancer Research, Medicon Village, Lund University, SE-223 81 Lund (Sweden); CREATE Health, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv (Israel)

    2014-02-28

    Highlights: • New anti-human EPOR antibody confirms full-length EPOR expression in breast cancer cells. • Proliferation of breast cancer cells is not affected by rhEPO treatment in vitro. • EPOR knockdown impairs proliferation of ERa positive breast cancer cells. • EPOR knockdown reduces AKT phosphorylation and ERa activity. - Abstract: The main function of Erythropoietin (EPO) and its receptor (EPOR) is the stimulation of erythropoiesis. Recombinant human EPO (rhEPO) is therefore used to treat anemia in cancer patients. However, clinical trials have indicated that rhEPO treatment might promote tumor progression and has a negative effect on patient survival. In addition, EPOR expression has been detected in several cancer forms. Using a newly produced anti-EPOR antibody that reliably detects the full-length isoform of the EPOR we show that breast cancer tissue and cells express the EPOR protein. rhEPO stimulation of cultured EPOR expressing breast cancer cells did not result in increased proliferation, overt activation of EPOR (receptor phosphorylation) or a consistent activation of canonical EPOR signaling pathway mediators such as JAK2, STAT3, STAT5, or AKT. However, EPOR knockdown experiments suggested functional EPO receptors in estrogen receptor positive (ERα{sup +}) breast cancer cells, as reduced EPOR expression resulted in decreased proliferation. This effect on proliferation was not seen in ERα negative cells. EPOR knockdown decreased ERα activity further supports a mechanism by which EPOR affects proliferation via ERα-mediated mechanisms. We show that EPOR protein is expressed in breast cancer cells, where it appears to promote proliferation by an EPO-independent mechanism in ERα expressing breast cancer cells.

  20. Environmental polycyclic aromatic hydrocarbons affect androgen receptor activation in vitro

    DEFF Research Database (Denmark)

    Vinggaard, Anne Marie; Hnida, Christina; Larsen, John Christian

    2000-01-01

    Nine structurally different polycyclic aromatic hydrocarbons (PAHs) were tested for their ability to either agonize or antagonize the human androgen receptor (hAR) in a sensitive reporter gene assay based on CHO cells transiently cotransfected with a hAR vector and an MMTV-LUC vector. Benz...

  1. Evaluation of properties of low activation Mn-Cr steel (2). Physical properties and aging properties

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Shigeru; Fukaya, Kiyoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishiyama, Shintaro [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Sato, Ikuo; Kusuhashi, Mikio; Hatakeyama, Takeshi [Japan Steel Works Ltd., Muroran, Hokkaido (Japan). Muroran Plant; Takahashi, Heishichiro [Hokkaido Univ., Sapporo (Japan); Kikuchi, Mitsuru [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2000-08-01

    The JT-60SU (Super Upgrade) program is under discussion at JAERI. Its design optimization activity requires the vacuum vessel material to be non-magnetic, very strong and with low induced activation. However, there is no suitable material available to fulfill all the requirements. JAERI started to develop a new material for the vacuum vessel together with the Japan Steel Works LTD. (JSW). Chemical composition and metallurgical processes were optimized and a new steel named VC9, which has the composition of Cr :16wt%, Mn :15.5wt%, C :0.2wt%, N :0.2wt% with nonmagnetic single {gamma} phase, was selected as a candidate material. Here, physical properties and aging properties of VC9 were studied and the results were compared with those of 316L stainless steel. (author)

  2. Reciprocal regulation of platelet responses to P2Y and thromboxane receptor activation.

    Science.gov (United States)

    Barton, J F; Hardy, A R; Poole, A W; Mundell, S J

    2008-03-01

    Thromboxane A(2) and ADP are two major platelet agonists that stimulate two sets of G protein-coupled receptors to activate platelets. Although aggregation responses to ADP and thromboxane desensitize, there are no reports currently addressing whether activation by one agonist may heterologously desensitize responses to the other. To demonstrate whether responses to ADP or U46619 may be modulated by prior treatment of platelets with the alternate agonist, revealing a level of cross-desensitization between receptor systems. Here we show that pretreatment of platelets with either agonist substantially desensitizes aggregation responses to the other agonist. Calcium responses to thromboxane receptor activation are desensitized by preactivation of P2Y(1) but not P2Y(12) receptors. This heterologous desensitization is mediated by a protein kinase C (PKC)-independent mechanism. Reciprocally, calcium responses to ADP are desensitized by pretreatment of platelets with the thromboxane analogue, U46619, and P2Y(12)-mediated inhibition of adenylate cyclase is also desensitized by pretreatment with U46619. In this direction, desensitization is comprised of two components, a true heterologous component that is PKC-independent, and a homologous component that is mediated through stimulated release of dense granule ADP. This study reveals cross-desensitization between ADP and thromboxane receptor signaling in human platelets. Cross-desensitization is mediated by protein kinases, involving PKC-dependent and independent pathways, and indicates that alterations in the activation state of one receptor may have effects upon the sensitivity of the other receptor system.

  3. Sch proteins are localized on endoplasmic reticulum membranes and are redistributed after tyrosine kinase receptor activation

    DEFF Research Database (Denmark)

    Lotti, L V; Lanfrancone, L; Migliaccio, E

    1996-01-01

    area of the cell and mostly associated with the cytosolic side of rough endoplasmic reticulum membranes. Upon epidermal growth factor treatment and receptor tyrosine kinase activation, the immunolabeling became peripheral and was found to be associated with the cytosolic surface of the plasma membrane....... The rough endoplasmic reticulum localization of Shc proteins in unstimulated cells and their massive recruitment to the plasma membrane, endocytic structures, and peripheral cytosol following receptor tyrosine kinase activation could account for multiple putative functions of the adaptor protein....

  4. 5-HT7 receptor activation: procognitive and antiamnesic effects.

    Science.gov (United States)

    Meneses, A; Perez-Garcia, G; Liy-Salmeron, G; Ponce-López, T; Lacivita, E; Leopoldo, M

    2015-02-01

    The serotonin (5-hydroxytryptamine (5-HT)) 5-HT7 receptor is localized in brain areas mediating memory; however, the role of this receptor on memory remains little explored. First, demonstrating the associative nature of Pavlovian/instrumental autoshaping (P/I-A) task, rats were exposed (three sessions) to CS-US (Pavlovian autoshaping), truly random control, free operant, and presentations of US or CS, and they were compared with rats trained-tested for one session to the P/I-A procedure. Also, effects of the 5-HT7 receptor agonist LP-211 administered intraperitoneally after training was determined on short- (1.5 h) and long-term memory 24 and 48 h) and on scopolamine-induced memory impairment and cAMP production. Autoshaping and its behavioral controls were studied. Other animals were subjected to an autoshaping training session and immediately afterwards were given (intraperitoneal) vehicle or LP-211 (0.1-10 mg/kg) and/or scopolamine (0.2 mg/kg) and tested for short-term memory (STM) and long-term memory (LTM); their brains were extracted for the cAMP ELISA immunoassay. P/I-A group produced the higher %CR. LP-211 did not affect STM; nonetheless, at 0.5 and 1.0 mg/kg, it improved LTM. The 5-HT7 receptor antagonist SB-269970 (SB; 10.0 mg/kg) alone had no effect; nevertheless, the LP-211 (1.0 mg/kg) LTM facilitation was reversed by SB. The scopolamine (0.2 mg/kg) induced-decrement in CR was accompanied by significant increased cAMP production. The scopolamine-induced decrement in CR and increments in cAMP were significantly attenuated by LP-211. Autoshaping is a reliable associative learning task whose consolidation is facilitated by the 5-HT7 receptor agonist LP-211.

  5. Activation of intracellular angiotensin AT2 receptors induces rapid cell death in human uterine leiomyosarcoma cells

    DEFF Research Database (Denmark)

    Zhao, Yi; Lützen, Ulf; Fritsch, Jürgen

    2015-01-01

    The presence of AT2 receptors in mitochondria and their role in NO generation and cell aging were recently demonstrated in various human and mouse non-tumour cells. We investigated the intracellular distribution of AT2 receptors including their presence in mitochondria and the role in the induction...... agonist, Compound 21 (C21) penetrates the cell membrane of quiescent SK-UT-1 cells, activates intracellular AT2 receptors and induces rapid cell death; approximately 70% of cells died within 24 h. The cells, which escaped from the cell death, displayed activation of the mitochondrial apoptotic pathway, i...

  6. Change in the properties of the opiate receptors of the brain under conditions of habituation of rats to morphine

    International Nuclear Information System (INIS)

    Zaitsev, S.V.; Sergeeva, M.G.; Chichenkov, O.N.; Petrov, V.E.; Varfolomeev, S.D.

    1987-01-01

    The influence of prolonged administration of morphine on the properties of the opiate receptors of the rat brain was investigated. For this purpose they conducted an analysis of the isotherms of binding of labeled μ-, σ-, and chi-ligands: morphine, D-Ala 2 , D-Leu 5 -enkephalin, and ethylketocyclazocin, with membrane preparations of the brains of rats tolerant to morphine, as well as the control animals. For a quantitative determination of the dissociation constants of the ligand-receptor complexes (K) and the concentration of the reagents ([Q]), they used differential method and the method of simulation modeling. It was shown that the values of K and [Q] for individual animals are subjected to substantial dispersion, whereas the ratios [Q]/K undergo minor individual fluctuations, both in the control group and in the group of rats tolerant to morphine. This permits the ratio [Q]/K to be singled out as one of the main parameters for comparing the properties of opiate receptors of various groups of animals. Using this criterion, as well as the method of simulated modeling, it was shown that the development of tolerance is accompanied by a change in the properties of the δ-receptors (the ratio [Q]/K decreases by a factor of more than two). In contrast to the δ-receptors, no significant influence of the tolerance on the properties of the μ- and chi-receptors, as well as the ultrahigh-affinity ligand binding sites, was detected

  7. Change in the properties of the opiate receptors of the brain under conditions of habituation of rats to morphine

    Energy Technology Data Exchange (ETDEWEB)

    Zaitsev, S.V.; Sergeeva, M.G.; Chichenkov, O.N.; Petrov, V.E.; Varfolomeev, S.D.

    1987-02-20

    The influence of prolonged administration of morphine on the properties of the opiate receptors of the rat brain was investigated. For this purpose they conducted an analysis of the isotherms of binding of labeled ..mu..-, sigma-, and chi-ligands: morphine, D-Ala/sup 2/, D-Leu/sup 5/-enkephalin, and ethylketocyclazocin, with membrane preparations of the brains of rats tolerant to morphine, as well as the control animals. For a quantitative determination of the dissociation constants of the ligand-receptor complexes (K) and the concentration of the reagents ((Q)), they used differential method and the method of simulation modeling. It was shown that the values of K and (Q) for individual animals are subjected to substantial dispersion, whereas the ratios (Q)/K undergo minor individual fluctuations, both in the control group and in the group of rats tolerant to morphine. This permits the ratio (Q)/K to be singled out as one of the main parameters for comparing the properties of opiate receptors of various groups of animals. Using this criterion, as well as the method of simulated modeling, it was shown that the development of tolerance is accompanied by a change in the properties of the delta-receptors (the ratio (Q)/K decreases by a factor of more than two). In contrast to the delta-receptors, no significant influence of the tolerance on the properties of the ..mu..- and chi-receptors, as well as the ultrahigh-affinity ligand binding sites, was detected.

  8. Activation of sigma-1 receptor chaperone in the treatment of neuropsychiatric diseases and its clinical implication

    Directory of Open Access Journals (Sweden)

    Kenji Hashimoto

    2015-01-01

    Full Text Available Endoplasmic reticulum (ER protein sigma-1 receptor represents unique chaperone activity in the central nervous system, and it exerts a potent influence on a number of neurotransmitter systems. Several lines of evidence suggest that activation of sigma-1 receptor plays a role in the pathophysiology of neuropsychiatric diseases, as well as in the mechanisms of some therapeutic drugs and neurosteroids. Preclinical studies showed that some selective serotonin reuptake inhibitors (SSRIs; fluvoxamine, fluoxetine, excitalopram, donepezil, and ifenprodil act as sigma-1 receptor agonists. Furthermore, sigma-1 receptor agonists could improve the N-methyl-D-aspartate (NMDA antagonist phencyclidine (PCP-induced cognitive deficits in mice. A study using positron emission tomography have demonstrated that an oral administration of fluvoxamine or donepezil could bind to sigma-1 receptor in the healthy human brain, suggesting that sigma-1 receptor might be involved in the therapeutic mechanisms of these drugs. Moreover, case reports suggest that sigma-1 receptor agonists, including fluvoxamine, and ifenprodil, may be effective in the treatment of cognitive impairment in schizophrenia, delirium in elderly people, and flashbacks in post-traumatic stress disorder. In this review article, the author would like to discuss the clinical implication of sigma-1 receptor agonists, including endogenous neurosteroids, in the neuropsychiatric diseases.

  9. Proteinase-activated receptors - mediators of early and delayed normal tissue radiation responses

    International Nuclear Information System (INIS)

    Hauer-Jensen, M.

    2003-01-01

    Proteinase-activated receptors (PARs) are G-protein coupled receptors that are activated by proteolytic exposure of a receptor-tethered ligand. The discovery of this receptor family represents one of the most intriguing recent developments in signal transduction. PARs are involved in the regulation of many normal and pathophysiological processes, notably inflammatory and fibroproliferative responses to injury. Preclinical studies performed in our laboratory suggest that proteinase-activated receptor-1 (PAR-1) plays a critical role in the mechanism of chronicity of radiation fibrosis, while proteinase-activated receptor-2 (PAR-2) may mediate important fibroproliferative responses in irradiated intestine. Specifically, activation of PAR-1 by thrombin, and PAR-2 by pancreatic trypsin and mast cell proteinases, appears to be involved in acute radiation-induced inflammation, as well as in subsequent extracellular matrix deposition, leading to the development of intestinal wall fibrosis and clinical complications. Pharmacological modulators of PAR-1 or PAR-2 expression or activation would be potentially useful as preventive or therapeutic agents in patients who receive radiation therapy, especially if blockade could be targeted to specific tissues or cellular compartments

  10. Sulfhydryl group content of chicken progesterone receptor: effect of oxidation on DNA binding activity

    International Nuclear Information System (INIS)

    Peleg, S.; Schrader, W.T.; O'Malley, B.W.

    1988-01-01

    DNA binding activity of chicken progesterone receptor B form (PRB) and A form (PRA) has been examined. This activity is strongly dependent upon the presence of thiols in the buffer. Stability studies showed that PRB was more sensitive to oxidation that was PRA. Receptor preparations were fractionated by DNA-cellulose chromatography to DNA-positive and DNA-negative subpopulations, and sulfhydryl groups were quantified on immunopurified receptor by labeling with [ 3 H]-N-ethylmaleimide. Labeling of DNA-negative receptors with [ 3 H]-N-ethylmaleimide showed 21-23 sulfhydryl groups on either PRA or PRB form when the proteins were reduced and denatured. A similar number was seen without reduction if denatured DNA-positive receptor species were tested. In contrast, the DNA-negative PRB had only 10-12 sulfhydryl groups detectable without reduction. A similar number (12-13 sulfhydryl groups) was found for PRA species that lost DNA binding activity after exposure to a nonreducing environment in vitro. The authors conclude that the naturally occurring receptor forms unable to bind to DNA, as well as receptor forms that have lost DNA binding activity due to exposure to nonreducing environment in vitro, contain 10-12 oxidized cysteine residues, likely present as disulfide bonds. Since they were unable to reduce the disulfide bonds when the native DNA-negative receptor proteins were treated with dithiothreitol (DTT), they speculate that irreversible loss of DNA binding activity of receptor in vitro is due to oxidation of cysteine residues that are not accessible to DTT in the native state

  11. Genotype-Dependent Difference in 5-HT2C Receptor-Induced Hypolocomotion: Comparison with 5-HT2A Receptor Functional Activity

    Directory of Open Access Journals (Sweden)

    Darya V. Bazovkina

    2015-01-01

    Full Text Available In the present study behavioral effects of the 5-HT2C serotonin receptor were investigated in different mouse strains. The 5-HT2C receptor agonist MK-212 applied intraperitoneally induced significant dose-dependent reduction of distance traveled in the open field test in CBA/Lac mice. This effect was receptor-specific because it was inhibited by the 5-HT2C receptor antagonist RS102221. To study the role of genotype in 5-HT2C receptor-induced hypolocomotion, locomotor activity of seven inbred mouse strains was measured after MK-212 acute treatment. We found that the 5-HT2C receptor stimulation by MK-212 decreased distance traveled in the open field test in CBA/Lac, C57Bl/6, C3H/He, and ICR mice, whereas it failed to affect locomotor activity in DBA/2J, Asn, and Balb/c mice. We also compared the interstrain differences in functional response to 5-HT2C and 5-HT2A receptors activation measured by the quantification of receptor-mediated head-twitches. These experiments revealed significant positive correlation between 5-HT2C and 5-HT2A receptors functional responses for all investigated mouse strains. Moreover, we found that 5-HT2A receptor activation with DOI did not change locomotor activity in CBA/Lac mice. Taken together, our data indicate the implication of 5-HT2C receptors in regulation of locomotor activity and suggest the shared mechanism for functional responses mediated by 5-HT2C and 5-HT2A receptors.

  12. Class A scavenger receptor promotes osteoclast differentiation via the enhanced expression of receptor activator of NF-{kappa}B (RANK)

    Energy Technology Data Exchange (ETDEWEB)

    Takemura, Kenichi [Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556 (Japan); Department of Orthopaedic and Neuro-Musculoskeletal Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto (Japan); Sakashita, Naomi; Fujiwara, Yukio; Komohara, Yoshihiro; Lei, XiaoFeng; Ohnishi, Koji [Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556 (Japan); Suzuki, Hiroshi [National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido (Japan); Kodama, Tatsuhiko [Department of Molecular Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo (Japan); Mizuta, Hiroshi [Department of Orthopaedic and Neuro-Musculoskeletal Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto (Japan); Takeya, Motohiro, E-mail: takeya@kumamoto-u.ac.jp [Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556 (Japan)

    2010-01-22

    Osteoclasts originate from bone marrow monocyte/macrophage lineage cells, and their differentiation depends on macrophage colony-stimulating factor (M-CSF) and receptor activator nuclear factor kappa B (RANK) ligand. Class A scavenger receptor (SR-A) is one of the principal functional molecules of macrophages, and its level of expression declines during osteoclast differentiation. To investigate the role of SR-A in osteoclastogenesis, we examined pathological changes in femoral bone and the expression levels of osteoclastogenesis-related molecules in SR-A{sup -/-} mice. The femoral osseous density of SR-A{sup -/-} mice was higher than that of SR-A{sup +/+} mice, and the number of multinucleated osteoclasts was significantly decreased. An in vitro differentiation assay revealed that the differentiation of multinucleated osteoclasts from bone marrow-derived progenitor cells is impaired in SR-A{sup -/-} mice. Elimination of SR-A did not alter the expression level of the M-CSF receptor, c-fms; however, the expression levels of RANK and RANK-related osteoclast-differentiation molecules such as nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 1 (NFATc1) and microphthalmia-associated transcription factor (MITF) significantly decreased. Furthermore, acetylated low-density lipoprotein (AcLDL), an SR-A ligand, significantly increased the expression level of RANK and MITF during osteoclast differentiation. These data indicate that SR-A promotes osteoclastogenesis via augmentation of the expression level of RANK and its related molecules.

  13. Self-phosphorylation of epidermal growth factor receptor: evidence for a model of intermolecular allosteric activation

    International Nuclear Information System (INIS)

    Yarden, Y.; Schlessinger, J.

    1987-01-01

    The membrane receptor for epidermal growth factor (EGF) is a 170,000 dalton glycoprotein composed of an extracellular EGF-binding domain and a cytoplasmic kinase domain connected by a stretch of 23 amino acids traversing the plasma membrane. The binding of EGF to the extracellular domain activates the cytoplasmic kinase function even in highly purified preparations of EGF receptor, suggesting that the activation occurs exclusively within the EGF receptor moiety. Conceivably, kinase activation may require the transfer of a conformational change through the single transmembrane region from the ligand binding domain to the cytoplasmic kinase region. Alternatively, ligand-induced receptor-receptor interactions may activate the kinase and thus bypass this requirement. Both mechanisms were contrasted by employing independent experimental approaches. On the basis of these results, an allosteric aggregation model is formulated for the activation of the cytoplasmic kinase function of the receptor by EGF. This model may be relevant to the mechanism by which the mitogenic signal of EGF is transferred across the membrane

  14. Carbobenzoxy amino acids: Structural requirements for cholecystokinin receptor antagonist activity

    International Nuclear Information System (INIS)

    Maton, P.N.; Sutliff, V.E.; Jensen, R.T.; Gardner, J.D.

    1985-01-01

    The authors used dispersed acini prepared from guinea pig pancreas to examine 28 carbobenzoxy (CBZ) amino acids for their abilities to function as cholecystokinin receptor antagonists. All amino acid derivatives tested, except for CBZ-alanine, CBZ-glycine, and N alpha-CBZ- lysine, were able to inhibit the stimulation of amylase secretion caused by the C-terminal octapeptide of cholecystokinin. In general, there was a good correlation between the ability of a carbobenzoxy amino acid to inhibit stimulated amylase secretion and the ability of the amino acid derivative to inhibit binding of 125 I-cholecystokinin. The inhibition of cholecystokinin-stimulated amylase secretion was competitive, fully reversible, and specific for those secretagogues that interact with the cholecystokinin receptor. The potencies with which the various carbobenzoxy amino acids inhibited the action of cholecystokinin varied 100-fold and CBZ-cystine was the most potent cholecystokinin receptor antagonist. This variation in potency was primarily but not exclusively a function of the hydrophobicity of the amino acid side chain

  15. Interaction of active compounds from Aegle marmelos CORREA with histamine-1 receptor

    Science.gov (United States)

    Nugroho, Agung Endro; Agistia, Dany Dwi; Tegar, Maulana; Purnomo, Hari

    2013-01-01

    The aim of this study is to determine the affinity of six active compounds of Aegle Marmelos Correa, they are (E, R)-Marmin, skimmianine, (S)-aegeline, aurapten, zeorin, and dustanin as antihistamines in histamine H1 receptor in comparison to cetirizin, diphenhydramine and chlorpheniramine as ligands comparison. Previously, in the in vitro study marmin obviously antagonized the histamine H1 receptor in a competitive manner. Methods: molecular docking to determine the interaction of ligand binding to its receptor. Lower docking score indicates more stable binding to that protein. Results: Marmin, skimmianine, aegeline, aurapten, zeorin, and dustanin were potential to develop as antihistamine agents, especially as histamine H1 receptor antagonists by interacting with amino acid residues, Asp107, Lys179, Lys191, Asn198, and Trp428 of histamine H1 receptor. Conclusions: Based on molecular docking, Amino acid residues involved in ligand protein interactions were Asp107, Lys179, Lys191, Asn198, and Trp428. PMID:23750086

  16. Pharmacology of the hypothermic response to 5-HT1A receptor activation in humans.

    Science.gov (United States)

    Lesch, K P; Poten, B; Söhnle, K; Schulte, H M

    1990-01-01

    The selective 5-HT1A receptor ligand ipsapirone (IPS) caused dose-related hypothermia in humans. The response was attenuated by the nonselective 5-HT1/2 receptor antagonist metergoline and was completely antagonized by the nonselective beta-adrenoceptor antagonist pindolol, which interacts stereoselectively with the 5-HT1A receptor. The selective beta 1-adrenergic antagonist betaxolol had no effect. The findings indicate that IPS-induced hypothermia specifically involves activation of (presynaptic) 5-HT1A receptors. Therefore, the hypothermic response to IPS may provide a convenient in vivo paradigma to assess the function of the presynaptic 5-HT receptor in affective disorders and its involvement in the effects of psychotropic drugs.

  17. Attenuation of eph receptor kinase activation in cancer cells by coexpressed ephrin ligands.

    Directory of Open Access Journals (Sweden)

    Giulia Falivelli

    Full Text Available The Eph receptor tyrosine kinases mediate juxtacrine signals by interacting "in trans" with ligands anchored to the surface of neighboring cells via a GPI-anchor (ephrin-As or a transmembrane segment (ephrin-Bs, which leads to receptor clustering and increased kinase activity. Additionally, soluble forms of the ephrin-A ligands released from the cell surface by matrix metalloproteases can also activate EphA receptor signaling. Besides these trans interactions, recent studies have revealed that Eph receptors and ephrins coexpressed in neurons can also engage in lateral "cis" associations that attenuate receptor activation by ephrins in trans with critical functional consequences. Despite the importance of the Eph/ephrin system in tumorigenesis, Eph receptor-ephrin cis interactions have not been previously investigated in cancer cells. Here we show that in cancer cells, coexpressed ephrin-A3 can inhibit the ability of EphA2 and EphA3 to bind ephrins in trans and become activated, while ephrin-B2 can inhibit not only EphB4 but also EphA3. The cis inhibition of EphA3 by ephrin-B2 implies that in some cases ephrins that cannot activate a particular Eph receptor in trans can nevertheless inhibit its signaling ability through cis association. We also found that an EphA3 mutation identified in lung cancer enhances cis interaction with ephrin-A3. These results suggest a novel mechanism that may contribute to cancer pathogenesis by attenuating the tumor suppressing effects of Eph receptor signaling pathways activated by ephrins in trans.

  18. Interactions of ligands with active and inactive conformations of the dopamine D2 receptor.

    Science.gov (United States)

    Malmberg, A; Mohell, N; Backlund Höök, B; Johansson, A M; Hacksell, U; Nordvall, G

    1998-04-10

    The affinities of 19 pharmacologically diverse dopamine D2 receptor ligands were determined for the active and inactive conformations of cloned human dopamine D2 receptors expressed in Ltk cells. The agonist [3H]quinpirole was used to selectively label the guanine nucleotide-binding protein-coupled, active receptor conformation. The antagonist [3H]raclopride, in the presence of the non-hydrolysable GTP-analogue Gpp(NH)p and sodium ions and in the absence of magnesium ions, was used to label the free inactive receptor conformation. The intrinsic activities of the ligands were determined in a forskolin-stimulated cyclic AMP assay using the same cells. An excellent correlation was shown between the affinity ratios (KR/KRG) of the ligands for the two receptor conformations and their intrinsic activity (r=0.96). The ligands included eight structurally related and enantiopure 2-aminotetralin derivatives; the enantiomers of 5-hydroxy-2-(dipropylamino)tetralin, 5-methoxy-2-(dipropylamino)tetralin, 5-fluoro-2-(dipropylamino)tetralin and 2-(dipropylamino)tetralin. The (S)-enantiomers behaved as full agonists in the cyclic AMP assay and displayed a large KR/KRG ratio. The (R)-enantiomers were classified as partial agonists and had lower ratios. The structure-affinity relationships of these compounds at the active and the inactive receptor conformations were analysed separately, and used in conjunction with a homology based receptor model of the dopamine D2 receptor. This led to proposed binding modes for agonists, antagonists and partial agonists in the 2-aminotetralin series. The concepts used in this study should be of value in the design of ligands with predetermined affinity and intrinsic activity.

  19. Two active molecular phenotypes of the tachykinin NK1 receptor revealed by G-protein fusions and mutagenesis.

    Science.gov (United States)

    Holst, B; Hastrup, H; Raffetseder, U; Martini, L; Schwartz, T W

    2001-06-08

    The NK1 neurokinin receptor presents two non-ideal binding phenomena, two-component binding curves for all agonists and significant differences between agonist affinity determined by homologous versus heterologous competition binding. Whole cell binding with fusion proteins constructed between either Galpha(s) or Galpha(q) and the NK1 receptor with a truncated tail, which secured non-promiscuous G-protein interaction, demonstrated monocomponent agonist binding closely corresponding to either of the two affinity states found in the wild-type receptor. High affinity binding of both substance P and neurokinin A was observed in the tail-truncated Galpha(s) fusion construct, whereas the lower affinity component was displayed by the tail-truncated Galpha(q) fusion. The elusive difference between the affinity determined in heterologous versus homologous binding assays for substance P and especially for neurokinin A was eliminated in the G-protein fusions. An NK1 receptor mutant with a single substitution at the extracellular end of TM-III-(F111S), which totally uncoupled the receptor from Galpha(s) signaling, showed binding properties that were monocomponent and otherwise very similar to those observed in the tail-truncated Galpha(q) fusion construct. Thus, the heterogenous pharmacological phenotype displayed by the NK1 receptor is a reflection of the occurrence of two active conformations or molecular phenotypes representing complexes with the Galpha(s) and Galpha(q) species, respectively. We propose that these molecular forms do not interchange readily, conceivably because of the occurrence of microdomains or "signal-transductosomes" within the cell membrane.

  20. The role and regulation of the peroxisome proliferator activated receptor alpha in human liver

    NARCIS (Netherlands)

    Kersten, Sander; Stienstra, Rinke

    2017-01-01

    The peroxisome proliferator-activated receptor α (PPARα) is a ligand-activated transcription factor that is abundantly expressed in liver. PPARα is activated by fatty acids and various other lipid species, as well as by a class of chemicals referred to as peroxisome proliferators. Studies in mice

  1. The soluble urokinase plasminogen activator receptor and its fragments in venous ulcers

    DEFF Research Database (Denmark)

    Ahmad, Anwar; Saha, Prakash; Evans, Colin

    2015-01-01

    OBJECTIVE: Activation of proteolytic mechanisms at the cell surface through the activity of urokinase-type plasminogen activator (uPA) bound to its receptor, uPAR, is an important process in wound healing. The soluble forms of uPAR (suPAR and its fragments I, II, and III) have nonproteolytic func...

  2. Tumorigenesis induced by the HHV8-encoded chemokine receptor requires ligand modulation of high constitutive activity

    DEFF Research Database (Denmark)

    Holst, P J; Rosenkilde, M M; Manfra, D

    2001-01-01

    sarcoma (KS). Here we demonstrate that several lines of mice carrying mutated receptors deficient in either constitutive activity or chemokine regulation fail to develop KS-like disease. In addition, animals expressing a receptor that preserves chemokine binding and constitutive activity but that does...... not respond to agonist stimulation have a much lower incidence of angiogenic lesions and tumors. These results indicate that induction of the KS-like disease in transgenic mice by ORF74 requires not only high constitutive signaling activity but also modulation of this activity by endogenous chemokines....

  3. Protease activated receptors (PARS) mediation in gyroxin biological activity; Mediacao dos receptores ativados por proteases (PARs) em atividades biologicas da giroxina

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Jose Alberto Alves da

    2009-07-01

    Gyroxin is a serine protease enzyme from the South American rattlesnake (Crotalus durissus terrificus) venom; it is only partially characterized and has multiple activities. Gyroxin induces blood coagulation, blood pressure decrease and a neurotoxic behavior named barrel rotation. The mechanisms involved in this neurotoxic activity are not known. Whereas gyroxin is a member of enzymes with high potential to become a new drug with clinical applications such as thrombin, batroxobin, ancrod, tripsyn and kalicrein, it is important to find out how gyroxin works. The analysis on agarose gel electrophoresis and circular dichroism confirmed the molecules' integrity and purity. The gyroxin intravenous administration in mice proved its neurotoxicity (barrel rotation). In vivo studies employing intravital microscopy proved that gyroxin induces vasodilation with the participation of protease activated receptors (PARs), nitric oxide and Na+K+ATPase. The leukocytes' adherence and rolling counting indicated that gyroxin has no pro inflammatory activity. Gyroxin induced platelet aggregation, which was blocked by inhibitors of PAR1 and PAR4 receptors (SCH 79797 and tcY-NH{sub 2}, respectively). Finally, it was proved that the gyroxin temporarily alter the permeability of the blood brain barrier (BBB). Our study has shown that both the protease-activated receptors and nitric oxide are mediators involved in the biological activities of gyroxin. (author)

  4. Activation of peroxisome proliferator-activated receptor-{alpha} enhances fatty acid oxidation in human adipocytes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joo-Young; Hashizaki, Hikari; Goto, Tsuyoshi; Sakamoto, Tomoya; Takahashi, Nobuyuki [Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 (Japan); Kawada, Teruo, E-mail: fat@kais.kyoto-u.ac.jp [Laboratory of Molecular Function of Food, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011 (Japan)

    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 human 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 expected

  5. Activation of the kinin B1 receptor attenuates melanoma tumor growth and metastasis.

    Directory of Open Access Journals (Sweden)

    Patricia Dillenburg-Pilla

    Full Text Available Melanoma is a very aggressive tumor that does not respond well to standard therapeutic approaches, such as radio- and chemotherapies. Furthermore, acquiring the ability to metastasize in melanoma and many other tumor types is directly related to incurable disease. The B1 kinin receptor participates in a variety of cancer-related pathophysiological events, such as inflammation and angiogenesis. Therefore, we investigated whether this G protein-coupled receptor plays a role in tumor progression. We used a murine melanoma cell line that expresses the kinin B1 receptor and does not express the kinin B2 receptor to investigate the precise contribution of activation of the B1 receptor in tumor progression and correlated events using various in vitro and in vivo approaches. Activation of the kinin B1 receptor in the absence of B2 receptor inhibits cell migration in vitro and decreases tumor formation in vivo. Moreover, tumors formed from cells stimulated with B1-specific agonist showed several features of decreased aggressiveness, such as smaller size and infiltration of inflammatory cells within the tumor area, higher levels of pro-inflammatory cytokines implicated in the host anti-tumor immune response, lower number of cells undergoing mitosis, a poorer vascular network, no signs of invasion of surrounding tissues or metastasis and increased animal survival. Our findings reveal that activation of the kinin B1 receptor has a host protective role during murine melanoma tumor progression, suggesting that the B1 receptor could be a new anti-tumor GPCR and provide new opportunities for therapeutic targeting.

  6. Activation of synaptic and extrasynaptic glycine receptors by taurine in preoptic hypothalamic neurons.

    Science.gov (United States)

    Bhattarai, Janardhan Prasad; Park, Soo Joung; Chun, Sang Woo; Cho, Dong Hyu; Han, Seong Kyu

    2015-11-03

    Taurine is an essential amino-sulfonic acid having a fundamental function in the brain, participating in both cell volume regulation and neurotransmission. Using a whole cell voltage patch clamp technique, the taurine-activated neurotransmitter receptors in the preoptic hypothalamic area (PHA) neurons were investigated. In the first set of experiments, different concentrations of taurine were applied on PHA neurons. Taurine-induced responses were concentration-dependent. Taurine-induced currents were action potential-independent and sensitive to strychnine, suggesting the involvement of glycine receptors. In addition, taurine activated not only α-homomeric, but also αβ-heteromeric glycine receptors in PHA neurons. Interestingly, a low concentration of taurine (0.5mM) activated glycine receptors, whereas a higher concentration (3mM) activated both glycine and gamma-aminobutyric acid A (GABAA) receptors in PHA neurons. These results suggest that PHA neurons are influenced by taurine and respond via glycine and GABAA receptors. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  7. Transcription control and neuronal differentiation by agents that activate the LXR nuclear receptor family.

    Science.gov (United States)

    Schmidt, A; Vogel, R; Holloway, M K; Rutledge, S J; Friedman, O; Yang, Z; Rodan, G A; Friedman, E

    1999-09-10

    LXR and PPAR receptors belong to the nuclear receptor superfamily of transcriptional activating factors. Using ligand-dependent transcription assays, we found that 5-tetradecyloxy-2-furancarboxylic acid (TOFA) transactivates chimeric receptors composed of the glucocorticoid receptor DNA binding domain and the ligand binding regions of PPARalpha, PPARbeta (NUC-1) and LXRbeta (NER) receptors. In the same assays, ligands for PPARs (oleic acid, WY-14643 and L-631,033) and LXRs (hydroxycholesterols) maintain their respective receptor selectivity. TOFA and hydroxycholesterols also stimulate transcription from a minimal fibrinogen promoter that is under the control of AP-1 or NF-kappaB transcription factor binding sites. In addition to their effects on transcription, these LXRbeta activators induce neuronal differentiation in rat pheochromocytoma cells. TOFA and the natural LXR agonist, 22 (R)-hydroxycholesterol, stimulate neurite outgrowth in 55 and 28% of cells, respectively. No neurite outgrowth was induced by the related 22(S)-hydroxycholesterol, which does not activate the LXR family. These results suggest that the hydroxycholesterol signaling pathway has a complex effect on transcription that mediates the activity of TOFA and hydroxycholesterol on neuronal differentiation in pheochromocytoma cells.

  8. Activation of muscarinic receptors protects against retinal neurons damage and optic nerve degeneration in vitro and in vivo models.

    Science.gov (United States)

    Tan, Pan-Pan; Yuan, Hai-Hong; Zhu, Xu; Cui, Yong-Yao; Li, Hui; Feng, Xue-Mei; Qiu, Yu; Chen, Hong-Zhuan; Zhou, Wei

    2014-03-01

    Muscarinic acetylcholine receptor agonist pilocarpine reduces intraocular pressure (IOP) of glaucoma mainly by stimulating ciliary muscle contraction and then increasing aqueous outflow. It is of our great interest to know whether pilocarpine has the additional properties of retinal neuroprotection independent of IOP lowering in vitro and in vivo models. In rat primary retinal cultures, cell viability was measured using an MTT assay and the trypan blue exclusion method, respectively. Retinal ganglion cells (RGCs) were identified by immunofluorescence and quantified by flow cytometry. For the in vivo study, the retinal damage after retinal ischemia/reperfusion injury in rats was evaluated by histopathological study using hematoxylin and eosin staining, transmission electron microscopy, and immunohistochemical study on cleaved caspase-3, caspase-3, and ChAT. Pretreatment of pilocarpine attenuated glutamate-induced neurotoxicity of primary retinal neurons in a dose-dependent manner. Protection of pilocarpine in both retinal neurons and RGCs was largely abolished by the nonselective muscarinic receptor antagonist atropine and the M1-selective muscarinic receptor antagonist pirenzepine. After ischemia/reperfusion injury in retina, the inner retinal degeneration occurred including ganglion cell layer thinning and neuron lost, and the optic nerve underwent vacuolar changes. These degenerative changes were significantly lessened by topical application of 2% pilocarpine. In addition, the protective effect of pilocarpine on the ischemic rat retina was favorably reflected by downregulating the expression of activated apoptosis marker cleaved caspase-3 and caspase-3 and upregulating the expression of cholinergic cell marker ChAT. Taken together, this highlights pilocarpine through the activation of muscarinic receptors appear to afford significant protection against retinal neurons damage and optic nerve degeneration at clinically relevant concentrations. These data also

  9. Activation of GLP-1 Receptor Promotes Bone Marrow Stromal Cell Osteogenic Differentiation through β-Catenin

    Directory of Open Access Journals (Sweden)

    Jingru Meng

    2016-04-01

    Full Text Available Glucagon-like peptide 1 (GLP-1 plays an important role in regulating bone remodeling, and GLP-1 receptor agonist shows a positive relationship with osteoblast activity. However, GLP-1 receptor is not found in osteoblast, and the mechanism of GLP-1 receptor agonist on regulating bone remodeling is unclear. Here, we show that the GLP-1 receptor agonist exendin-4 (Ex-4 promoted bone formation and increased bone mass and quality in a rat unloading-induced bone loss model. These functions were accompanied by an increase in osteoblast number and serum bone formation markers, while the adipocyte number was decreased. Furthermore, GLP-1 receptor was detected in bone marrow stromal cells (BMSCs, but not in osteoblast. Activation of GLP-1 receptor by Ex-4 promoted the osteogenic differentiation and inhibited BMSC adipogenic differentiation through regulating PKA/β-catenin and PKA/PI3K/AKT/GSK3β signaling. These findings reveal that GLP-1 receptor regulates BMSC osteogenic differentiation and provide a molecular basis for therapeutic potential of GLP-1 against osteoporosis.

  10. Mood states, sympathetic activity, and in vivo beta-adrenergic receptor function in a normal population.

    Science.gov (United States)

    Yu, Bum-Hee; Kang, Eun-Ho; Ziegler, Michael G; Mills, Paul J; Dimsdale, Joel E

    2008-01-01

    The purpose of this study was to examine the relationship between mood states and beta-adrenergic receptor function in a normal population. We also examined if sympathetic nervous system activity is related to mood states or beta-adrenergic receptor function. Sixty-two participants aged 25-50 years were enrolled in this study. Mood states were assessed using the Profile of Mood States (POMS). Beta-adrenergic receptor function was determined using the chronotropic 25 dose isoproterenol infusion test. Level of sympathetic nervous system activity was estimated from 24-hr urine norepinephrine excretion. Higher tension-anxiety, depression-dejection, and anger-hostility were related to decreased beta-adrenergic receptor sensitivity (i.e., higher chronotropic 25 dose values), but tension-anxiety was the only remaining independent predictor of beta-adrenergic receptor function after controlling for age, gender, ethnicity, and body mass index (BMI). Urinary norepinephrine excretion was unrelated to either mood states or beta-adrenergic receptor function. These findings replicate previous reports that anxiety is related to decreased (i.e., desensitized) beta-adrenergic receptor sensitivity, even after controlling for age, gender, ethnicity, and body mass index.

  11. Analgesic tone conferred by constitutively active mu opioid receptors in mice lacking β-arrestin 2

    Directory of Open Access Journals (Sweden)

    Hales Tim G

    2011-04-01

    Full Text Available Abstract Hedonic reward, dependence and addiction are unwanted effects of opioid analgesics, linked to the phasic cycle of μ opioid receptor activation, tolerance and withdrawal. In vitro studies of recombinant G protein coupled receptors (GPCRs over expressed in cell lines reveal an alternative tonic signaling mechanism that is independent of agonist. Such studies demonstrate that constitutive GPCR signaling can be inhibited by inverse agonists but not by neutral antagonists. However, ligand-independent activity has been difficult to examine in vivo, at the systems level, due to relatively low levels of constitutive activity of most GPCRs including μ receptors, often necessitating mutagenesis or pharmacological manipulation to enhance basal signaling. We previously demonstrated that the absence of β-arrestin 2 (β-arr2 augments the constitutive coupling of μ receptors to voltage-activated Ca2+ channels in primary afferent dorsal root ganglion neurons from β-arr2-/- mice. We used this in vitro approach to characterize neutral competitive antagonists and inverse agonists of the constitutively active wild type μ receptors in neurons. We administered these agents to β-arr2-/- mice to explore the role of constitutive μ receptor activity in nociception and hedonic tone. This study demonstrates that the induction of constitutive μ receptor activity in vivo in β-arr2-/- mice prolongs tail withdrawal from noxious heat, a phenomenon that was reversed by inverse agonists, but not by antagonists that lack negative efficacy. By contrast, the aversive effects of inverse agonists were similar in β-arr2-/- and β-arr2+/+ mice, suggesting that hedonic tone was unaffected.

  12. receptores

    Directory of Open Access Journals (Sweden)

    Salete Regina Daronco Benetti

    2006-01-01

    Full Text Available Se trata de un estudio etnográfico, que tuvo lo objetivo de interpretar el sistema de conocimiento y del significado atribuidos a la sangre referente a la transfusión sanguínea por los donadores y receptores de un banco de sangre. Para la colecta de las informaciones se observaron los participantes y la entrevista etnográfica se realizó el análisis de dominio, taxonómicos y temáticos. Los dominios culturales fueron: la sangre es vida: fuente de vida y alimento valioso; creencias religiosas: fuentes simbólicas de apoyos; donación sanguínea: un gesto colaborador que exige cuidarse, gratifica y trae felicidad; donación sanguínea: fuente simbólica de inseguridad; estar enfermo es una condición para realizar transfusión sanguínea; transfusión sanguínea: esperanza de vida; Creencias populares: transfusión sanguínea como riesgo para la salud; donadores de sangre: personas benditas; donar y recibir sangre: como significado de felicidad. Temática: “líquido precioso que origina, sostiene, modifica la vida, provoca miedo e inseguridad”.

  13. How does high-frequency sound or vibration activate vestibular receptors?

    Science.gov (United States)

    Curthoys, I S; Grant, J W

    2015-03-01

    The mechanism by which vestibular neural phase locking occurs and how it relates to classical otolith mechanics is unclear. Here, we put forward the hypothesis that sound and vibration both cause fluid pressure waves in the inner ear and that it is these pressure waves which displace the hair bundles on vestibular receptor hair cells and result in activation of type I receptor hair cells and phase locking of the action potentials in the irregular vestibular afferents, which synapse on type I receptors. This idea has been suggested since the early neural recordings and recent results give it greater credibility.

  14. Molecular simulation of receptors of physiologically active compounds for purposes of medical chemistry

    Science.gov (United States)

    Baskin, Igor I.; Palyulin, Vladimir A.; Zefirov, Nikolai S.

    2009-06-01

    The general strategy of the molecular simulation of biological receptors and their interaction with ligands is considered. The procedures for construction of 3D protein models, molecular docking, evaluation of model quality, determination of the free energy of protein binding with ligands are discussed. The methods of molecular design of new medicaments based on molecular models of biological targets: virtual screening and de novo design, are presented. Examples of the above-listed approaches for the simulation of a number of pharmacologically significant receptors, analysis of receptor-ligand interactions and design of new biologically active organic compounds are given.

  15. Molecular simulation of receptors of physiologically active compounds for purposes of medical chemistry

    International Nuclear Information System (INIS)

    Baskin, Igor I; Palyulin, Vladimir A; Zefirov, Nikolai S

    2009-01-01

    The general strategy of the molecular simulation of biological receptors and their interaction with ligands is considered. The procedures for construction of 3D protein models, molecular docking, evaluation of model quality, determination of the free energy of protein binding with ligands are discussed. The methods of molecular design of new medicaments based on molecular models of biological targets: virtual screening and de novo design, are presented. Examples of the above-listed approaches for the simulation of a number of pharmacologically significant receptors, analysis of receptor-ligand interactions and design of new biologically active organic compounds are given.

  16. Molecular simulation of receptors of physiologically active compounds for purposes of medical chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Baskin, Igor I; Palyulin, Vladimir A; Zefirov, Nikolai S [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2009-06-30

    The general strategy of the molecular simulation of biological receptors and their interaction with ligands is considered. The procedures for construction of 3D protein models, molecular docking, evaluation of model quality, determination of the free energy of protein binding with ligands are discussed. The methods of molecular design of new medicaments based on molecular models of biological targets: virtual screening and de novo design, are presented. Examples of the above-listed approaches for the simulation of a number of pharmacologically significant receptors, analysis of receptor-ligand interactions and design of new biologically active organic compounds are given.

  17. Cognitive improvement by activation of alpha7 nicotinic acetylcholine receptors: from animal models to human pathophysiology

    DEFF Research Database (Denmark)

    Thomsen, Morten S; Hansen, Henrik H; Timmerman, Daniel B

    2010-01-01

    Agonists and positive allosteric modulators of the alpha(7) nicotinic acetylcholine receptor (nAChR) are currently being developed for the treatment of cognitive disturbances in patients with schizophrenia or Alzheimer's disease. This review describes the neurobiological properties of the alpha n...

  18. Rheumatic Disease: Protease-Activated Receptor-2 in Synovial Joint Pathobiology

    Directory of Open Access Journals (Sweden)

    Kendal McCulloch

    2018-05-01

    Full Text Available Protease-activated receptor-2 (PAR2 is one member of a small family of transmembrane, G-protein-coupled receptors. These receptors are activated via cleavage of their N terminus by serine proteases (e.g., tryptase, unveiling an N terminus tethered ligand which binds to the second extracellular loop of the receptor. Increasing evidence has emerged identifying key pathophysiological roles for PAR2 in both rheumatoid arthritis (RA and osteoarthritis (OA. Importantly, this includes both pro-inflammatory and destructive roles. For example, in murine models of RA, the associated synovitis, cartilage degradation, and subsequent bone erosion are all significantly reduced in the absence of PAR2. Similarly, in experimental models of OA, PAR2 disruption confers protection against cartilage degradation, subchondral bone osteosclerosis, and osteophyte formation. This review focuses on the role of PAR2 in rheumatic disease and its potential as an important therapeutic target for treating pain and joint degradation.

  19. Thyroid hormone and retinoic acid nuclear receptors: specific ligand-activated transcription factors

    International Nuclear Information System (INIS)

    Brtko, J.

    1998-01-01

    Transcriptional regulation by both the thyroid hormone and the vitamin A-derived 'retinoid hormones' is a critical component in controlling many aspects of higher vertebrate development and metabolism. Their functions are mediated by nuclear receptors, which comprise a large super-family of ligand-inducible transcription factors. Both the thyroid hormone and the retinoids are involved in a complex arrangement of physiological and development responses in many tissues of higher vertebrates. The functions of 3,5,3'-triiodothyronine (T 3 ), the thyromimetically active metabolite of thyroxine as well as all-trans retinoic acid, the biologically active vitamin A metabolite are mediated by nuclear receptor proteins that are members of the steroid/thyroid/retinoid hormone receptor family. The functions of all members of the receptor super family are discussed. (authors)

  20. Mechanical stress activates NMDA receptors in the absence of agonists

    OpenAIRE

    Maneshi, Mohammad Mehdi; Maki, Bruce; Gnanasambandam, Radhakrishnan; Belin, Sophie; Popescu, Gabriela K.; Sachs, Frederick; Hua, Susan Z.

    2017-01-01

    While studying the physiological response of primary rat astrocytes to fluid shear stress in a model of traumatic brain injury (TBI), we found that shear stress induced Ca2+ entry. The influx was inhibited by MK-801, a specific pore blocker of N-Methyl-D-aspartic acid receptor (NMDAR) channels, and this occurred in the absence of agonists. Other NMDA open channel blockers ketamine and memantine showed a similar effect. The competitive glutamate antagonists AP5 and GluN2B-selective inhibitor i...

  1. Structural motifs of importance for the constitutive activity of the orphan 7TM receptor EBI2: analysis of receptor activation in the absence of an agonist

    DEFF Research Database (Denmark)

    Benned-Jensen, Tau; Rosenkilde, Mette M

    2008-01-01

    were identified by a systematic mutational analysis of 29 residues in EBI2. The cAMP response element-binding protein transcription factor was used as a measure of receptor activity and was correlated to the receptor surface expression. PheVI:13 (Phe257), and the neighboring CysVI:12 (Cys256......, but not to Lys, decreased the constitutive activity more than 7-fold compared with wt EBI2. IleIII:03 (Ile106) is located only 4 A from ArgII:20, and a favorable electrostatic interaction with ArgII:20 was created by introduction of Glu in III:03, given that the activity increased to 4.4-fold of that wt EBI2...

  2. A urokinase receptor-associated protein with specific collagen binding properties

    DEFF Research Database (Denmark)

    Behrendt, N; Jensen, O N; Engelholm, L H

    2000-01-01

    membrane-bound lectin with hitherto unknown function. The human cDNA was cloned and sequenced. The protein, designated uPARAP, is a member of the macrophage mannose receptor protein family and contains a putative collagen-binding (fibronectin type II) domain in addition to 8 C-type carbohydrate recognition...... domains. It proved capable of binding strongly to a single type of collagen, collagen V. This collagen binding reaction at the exact site of plasminogen activation on the cell may lead to adhesive functions as well as a contribution to cellular degradation of collagen matrices....

  3. Neuroprotective properties of a novel, non-haematopoietic agonist of the erythropoietin receptor

    DEFF Research Database (Denmark)

    Pankratova, Stanislava; Kiryushko, Dar'Ya; Sonn, Katrin

    2010-01-01

    they are involved in tissue protection. However, the use of erythropoietin as a neuroprotective agent may be hampered by its erythropoietic activity. Therefore, developing non-haematopoietic erythropoietin mimetics is important. Based on the crystal structure of the complex of erythropoietin and its receptor, we...... attenuated seizures, decreased mortality and reduced neurodegeneration in an in vivo model of kainic acid-induced neurotoxicity. In contrast to erythropoietin, Epotris did not stimulate erythropoiesis upon chronic administration. Thus, Epotris is a novel neuroprotective non-haematopoietic erythropoietin...

  4. Proteolytic fragmentation of inositol 1,4,5-trisphosphate receptors: a novel mechanism regulating channel activity?

    Science.gov (United States)

    Wang, Liwei; Alzayady, Kamil J; Yule, David I

    2016-06-01

    Inositol 1,4,5-trisphosphate receptors (IP3 Rs) are a family of ubiquitously expressed intracellular Ca(2+) release channels. Regulation of channel activity by Ca(2+) , nucleotides, phosphorylation, protein binding partners and other cellular factors is thought to play a major role in defining the specific spatiotemporal characteristics of intracellular Ca(2+) signals. These properties are, in turn, believed pivotal for the selective and specific physiological activation of Ca(2+) -dependent effectors. IP3 Rs are also substrates for the intracellular cysteine proteases, calpain and caspase. Cleavage of the IP3 R has been proposed to play a role in apoptotic cell death by uncoupling regions important for IP3 binding from the channel domain, leaving an unregulated leaky Ca(2+) pore. Contrary to this hypothesis, we demonstrate following proteolysis that N- and C-termini of IP3 R1 remain associated, presumably through non-covalent interactions. Further, we show that complementary fragments of IP3 R1 assemble into tetrameric structures and retain their ability to be regulated robustly by IP3 . While peptide continuity is clearly not necessary for IP3 -gating of the channel, we propose that cleavage of the IP3 R peptide chain may alter other important regulatory events to modulate channel activity. In this scenario, stimulation of the cleaved IP3 R may support distinct spatiotemporal Ca(2+) signals and activation of specific effectors. Notably, in many adaptive physiological events, the non-apoptotic activities of caspase and calpain are demonstrated to be important, but the substrates of the proteases are poorly defined. We speculate that proteolytic fragmentation may represent a novel form of IP3 R regulation, which plays a role in varied adaptive physiological processes. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

  5. Acutely increasing δGABAA receptor activity impairs memory and inhibits synaptic plasticity in the hippocampus

    Science.gov (United States)

    Whissell, Paul D.; Eng, Dave; Lecker, Irene; Martin, Loren J.; Wang, Dian-Shi; Orser, Beverley A.

    2013-01-01

    Extrasynaptic γ-aminobutyric acid type A (GABAA) receptors that contain the δ subunit (δGABAA receptors) are expressed in several brain regions including the dentate gyrus (DG) and CA1 subfields of the hippocampus. Drugs that increase δGABAA receptor activity have been proposed as treatments for a variety of disorders including insomnia, epilepsy and chronic pain. Also, long-term pretreatment with the δGABAA receptor–preferring agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) enhances discrimination memory and increases neurogenesis in the DG. Despite the potential therapeutic benefits of such treatments, the effects of acutely increasing δGABAA receptor activity on memory behaviors remain unknown. Here, we studied the effects of THIP (4 mg/kg, i.p.) on memory performance in wild-type (WT) and δGABAA receptor null mutant (Gabrd−/−) mice. Additionally, the effects of THIP on long-term potentiation (LTP), a molecular correlate of memory, were studied within the DG and CA1 subfields of the hippocampus using electrophysiological recordings of field potentials in hippocampal slices. The results showed that THIP impaired performance in the Morris water maze, contextual fear conditioning and object recognition tasks in WT mice but not Gabrd−/− mice. Furthermore, THIP inhibited LTP in hippocampal slices from WT but not Gabrd−/− mice, an effect that was blocked by GABAA receptor antagonist bicuculline. Thus, acutely increasing δGABAA receptor activity impairs memory behaviors and inhibits synaptic plasticity. These results have important implications for the development of therapies aimed at increasing δGABAA receptor activity. PMID:24062648

  6. Acutely increasing δGABAA receptor activity impairs memory and inhibits synaptic plasticity in the hippocampus

    Directory of Open Access Journals (Sweden)

    Paul David Whissell

    2013-09-01

    Full Text Available Extrasynaptic γ-aminobutyric acid type A (GABAA receptors that contain the δ subunit (δGABAA receptors are expressed in several brain regions including the dentate gyrus (DG and CA1 subfields of the hippocampus. Drugs that increase δGABAA receptor activity have been proposed as treatments for a variety of disorders including insomnia, epilepsy and chronic pain. Also, long-term pretreatment with the δGABAA receptor–preferring agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP enhances discrimination memory and increases neurogenesis in the DG. Despite the potential therapeutic benefits of such treatments, the effects of acutely increasing δGABAA receptor activity on memory behaviors remain unknown. Here, we studied the effects of THIP (4 mg/kg, i.p. on memory performance in wild-type (WT and δGABAA receptor null mutant (Gabrd–/– mice. Additionally, the effects of THIP on long-term potentiation (LTP, a molecular correlate of memory, were studied within the DG and CA1 subfields of the hippocampus using electrophysiological recordings of field potentials in hippocampal slices. The results showed that THIP impaired performance in the Morris water maze, contextual fear conditioning and object recognition tasks in WT mice but not Gabrd–/– mice. Furthermore, THIP inhibited LTP in hippocampal slices from WT but not Gabrd–/– mice, an effect that was blocked by GABAA receptor antagonist bicuculline. Thus, acutely increasing δGABAA receptor activity impairs memory behaviors and inhibits synaptic plasticity. These results have important implications for the development of therapies aimed at increasing δGABAA receptor activity.

  7. Cow's milk increases the activities of human nuclear receptors peroxisome proliferator-activated receptors alpha and delta and retinoid X receptor alpha involved in the regulation of energy homeostasis, obesity, and inflammation.

    Science.gov (United States)

    Suhara, W; Koide, H; Okuzawa, T; Hayashi, D; Hashimoto, T; Kojo, H

    2009-09-01

    The nuclear peroxisome proliferator-activated receptors (PPAR) have been shown to play crucial roles in regulating energy homeostasis including lipid and carbohydrate metabolism, inflammatory responses, and cell proliferation, differentiation, and survival. Because PPAR agonists have the potential to prevent or ameliorate diseases such as hyperlipidemia, diabetes, atherosclerosis, and obesity, we have explored new natural agonists for PPAR. For this purpose, cow's milk was tested for agonistic activity toward human PPAR subtypes using a reporter gene assay. Milk increased human PPARalpha activity in a dose-dependent manner with a 3.2-fold increase at 0.5% (vol/vol). It also enhanced human PPARdelta activity in a dose-dependent manner with an 11.5-fold increase at 0.5%. However, it only slightly affected human PPARgamma activity. Ice cream, butter, and yogurt also increased the activities of PPARalpha and PPARdelta, whereas vegetable cream affected activity of PPARdelta but not PPARalpha. Skim milk enhanced the activity of PPAR to a lesser degree than regular milk. Milk and fresh cream increased the activity of human retinoid X receptor (RXR)alpha as well as PPARalpha and PPARdelta, whereas neither affected vitamin D3 receptor, estrogen receptors alpha and beta, or thyroid receptors alpha and beta. Both milk and fresh cream were shown by quantitative real-time PCR to increase the quantity of mRNA for uncoupling protein 2 (UCP2), an energy expenditure gene, in a dose-dependent manner. The increase in UCP2 mRNA was found to be reduced by treatment with PPARdelta-short interfering (si)RNA. This study unambiguously clarified at the cellular level that cow's milk increased the activities of human PPARalpha, PPARdelta, and RXRalpha. The possible role in enhancing the activities of PPARalpha, PPARdelta, and RXRalpha, and the health benefits of cow's milk were discussed.

  8. Histamine induces microglia activation and dopaminergic neuronal toxicity via H1 receptor activation.

    Science.gov (United States)

    Rocha, Sandra M; Saraiva, Tatiana; Cristóvão, Ana C; Ferreira, Raquel; Santos, Tiago; Esteves, Marta; Saraiva, Cláudia; Je, Goun; Cortes, Luísa; Valero, Jorge; Alves, Gilberto; Klibanov, Alexander; Kim, Yoon-Seong; Bernardino, Liliana

    2016-06-04

    Histamine is an amine widely known as a peripheral inflammatory mediator and as a neurotransmitter in the central nervous system. Recently, it has been suggested that histamine acts as an innate modulator of microglial activity. Herein, we aimed to disclose the role of histamine in microglial phagocytic activity and reactive oxygen species (ROS) production and to explore the consequences of histamine-induced neuroinflammation in dopaminergic (DA) neuronal survival. The effect of histamine on phagocytosis was assessed both in vitro by using a murine N9 microglial cell line and primary microglial cell cultures and in vivo. Cells were exposed to IgG-opsonized latex beads or phosphatidylserine (PS) liposomes to evaluate Fcγ or PS receptor-mediated microglial phagocytosis, respectively. ROS production and protein levels of NADPH oxidases and Rac1 were assessed as a measure of oxidative stress. DA neuronal survival was evaluated in vivo by counting the number of tyrosine hydroxylase-positive neurons in the substantia nigra (SN) of mice. We found that histamine triggers microglial phagocytosis via histamine receptor 1 (H1R) activation and ROS production via H1R and H4R activation. By using apocynin, a broad NADPH oxidase (Nox) inhibitor, and Nox1 knockout mice, we found that the Nox1 signaling pathway is involved in both phagocytosis and ROS production induced by histamine in vitro. Interestingly, both apocynin and annexin V (used as inhibitor of PS-induced phagocytosis) fully abolished the DA neurotoxicity induced by the injection of histamine in the SN of adult mice in vivo. Blockade of H1R protected against histamine-induced Nox1 expression and death of DA neurons in vivo. Overall, our results highlight the relevance of histamine in the modulation of microglial activity that ultimately may interfere with neuronal survival in the context of Parkinson's disease (PD) and, eventually, other neurodegenerative diseases which are accompanied by microglia

  9. Exercise reduces adipose tissue via cannabinoid receptor type 1 which is regulated by peroxisome proliferator-activated receptor

    International Nuclear Information System (INIS)

    Yan Zhencheng; Liu Daoyan; Zhang Lili; Shen Chenyi; Ma Qunli; Cao Tingbing; Wang Lijuan; Nie Hai; Zidek, Walter; Tepel, Martin; Zhu Zhiming

    2007-01-01

    Obesity is one major cardiovascular risk factor. We tested effects of endurance exercise on cannabinoid receptor type 1 (CB1) and peroxisome proliferator-activated receptor-δ (PPAR-δ)-dependent pathways in adipose tissue. Male Wistar rats were randomly assigned to standard laboratory chow or a high-fat diet without and with regular endurance exercise. Exercise in rats on high-fat diet significantly reduced visceral fat mass, blood pressure, and adipocyte size (each p < 0.05). Adipocyte hypertrophy induced by high-fat diet was accompanied by increased CB1 expression in adipose tissue, whereas exercise significantly reduced CB1 expression (each p < 0.05). CB1 receptor expression and adipocyte differentiation were directly regulated by PPAR-δ. Adipocyte hypertrophy induced by high-fat diet was accompanied by reduced PPAR-δ. Furthermore, selective silencing of PPAR-δ by RNA interference in 3T3-L1-preadipocyte cells significantly increased CB1 expression from 1.00 ± 0.06 (n = 3) to 1.91 ± 0.06 (n = 3; p < 0.01) and increased adipocyte differentiation, whereas adenovirus-mediated overexpression of PPAR-δ significantly reduced CB1 expression to 0.39 ± 0.03 (n = 3; p < 0.01) and reduced adipocyte differentiation. In the presence of the CB1 antagonist rimonabant adipocyte differentiation in stimulated 3T3 L1 preadipocyte cells was significantly reduced. The study indicates that high-fat diet-induced hypertrophy of adipocytes is associated with increased CB1 receptor expression which is directly regulated by PPAR-δ. Both CB1 and PPAR-δ are intimately involved in therapeutic interventions against a most important cardiovascular risk factor

  10. Natural compounds regulate energy metabolism by the modulating the activity of lipid-sensing nuclear receptors.

    Science.gov (United States)

    Goto, Tsuyoshi; Kim, Young-Il; Takahashi, Nobuyuki; Kawada, Teruo

    2013-01-01

    Obesity causes excess fat accumulation in various tissues, most notoriously in the adipose tissue, along with other insulin-responsive organs such as skeletal muscle and the liver, which predisposes an individual to the development of metabolic abnormalities. The molecular mechanisms underlying obesity-induced metabolic abnormalities have not been completely elucidated; however, in recent years, the search for therapies to prevent the development of obesity and obesity-associated metabolic disorders has increased. It is known that several nuclear receptors, when activated by specific ligands, regulate carbohydrate and lipid metabolism at the transcriptional level. The expression of lipid metabolism-related enzymes is directly regulated by the activity of various nuclear receptors via their interaction with specific response elements in promoters of those genes. Many natural compounds act as ligands of nuclear receptors and regulate carbohydrate and lipid metabolism by regulating the activities of these nuclear receptors. In this review, we describe our current knowledge of obesity, the role of lipid-sensing nuclear receptors in energy metabolism, and several examples of food factors that act as agonists or antagonists of nuclear receptors, which may be useful for the management of obesity and the accompanying energy metabolism abnormalities. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Telmisartan prevents weight gain and obesity through activation of peroxisome proliferator-activated receptor-delta-dependent pathways

    DEFF Research Database (Denmark)

    He, Hongbo; Yang, Dachun; Ma, Liqun

    2010-01-01

    Telmisartan shows antihypertensive and several pleiotropic effects that interact with metabolic pathways. In the present study we tested the hypothesis that telmisartan prevents adipogenesis in vitro and weight gain in vivo through activation of peroxisome proliferator-activated receptor (PPAR)-d...

  12. Peroxisome Proliferator-activated Receptor gamma Regulates Expression of the Anti-lipolytic G-protein-coupled Receptor 81 (GPR81/Gpr81)

    NARCIS (Netherlands)

    Jeninga, E.H.; Bugge, A.; Nielsen, R.; Kersten, A.H.; Hamers, N.; Dani, C.; Wabitsch, M.; Berger, R.; Stunnenberg, H.G.; Mandrup, S.; Kalkhoven, E.

    2009-01-01

    The ligand-inducible nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR gamma) plays a key role in the differentiation, maintenance, and function of adipocytes and is the molecular target for the insulin-sensitizing thiazoledinediones (TZDs). Although a number of PPAR gamma

  13. Peptides derived from specific interaction sites of the fibroblast growth factor 2 - FGF receptor complexes induce receptor activation and signaling

    DEFF Research Database (Denmark)

    Manfè, Valentina; Kochoyan, Artur; Bock, Elisabeth

    2010-01-01

    J. Neurochem. (2010) 10.1111/j.1471-4159.2010.06718.x Abstract Basic fibroblast growth factor (FGF2, bFGF) is the most extensively studied member of the FGF family and is involved in neurogenesis, differentiation, neuroprotection, and synaptic plasticity in the CNS. FGF2 executes its pleiotropic...... biologic actions by binding, dimerizing, and activating FGF receptors (FGFRs). The present study reports the physiologic impact of various FGF2-FGFR1 contact sites employing three different synthetic peptides, termed canofins, designed based on structural analysis of the interactions between FGF2 and FGFR1...

  14. Reactivation of desensitized formyl peptide receptors by platelet activating factor: a novel receptor cross talk mechanism regulating neutrophil superoxide anion production.

    Directory of Open Access Journals (Sweden)

    Huamei Forsman

    Full Text Available Neutrophils express different chemoattractant receptors of importance for guiding the cells from the blood stream to sites of inflammation. These receptors communicate with one another, a cross talk manifested as hierarchical, heterologous receptor desensitization. We describe a new receptor cross talk mechanism, by which desensitized formyl peptide receptors (FPRdes can be reactivated. FPR desensitization is induced through binding of specific FPR agonists and is reached after a short period of active signaling. The mechanism that transfers the receptor to a non-signaling desensitized state is not known, and a signaling pathway has so far not been described, that transfers FPRdes back to an active signaling state. The reactivation signal was generated by PAF stimulation of its receptor (PAFR and the cross talk was uni-directional. LatrunculinA, an inhibitor of actin polymerization, induced a similar reactivation of FPRdes as PAF while the phosphatase inhibitor CalyculinA inhibited reactivation, suggesting a role for the actin cytoskeleton in receptor desensitization and reactivation. The activated PAFR could, however, reactivate FPRdes also when the cytoskeleton was disrupted prior to activation. The receptor cross talk model presented prophesies that the contact on the inner leaflet of the plasma membrane that blocks signaling between the G-protein and the FPR is not a point of no return; the receptor cross-talk from the PAFRs to the FPRdes initiates an actin-independent signaling pathway that turns desensitized receptors back to a signaling state. This represents a novel mechanism for amplification of neutrophil production of reactive oxygen species.

  15. Structural mechanism of ligand activation in human calcium-sensing receptor

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Yong; Mosyak, Lidia; Kurinov, Igor; Zuo, Hao; Sturchler, Emmanuel; Cheng, Tat Cheung; Subramanyam, Prakash; Brown, Alice P.; Brennan, Sarah C.; Mun, Hee-chang; Bush, Martin; Chen, Yan; Nguyen, Trang X.; Cao, Baohua; Chang, Donald D.; Quick, Matthias; Conigrave, Arthur D.; Colecraft, Henry M.; McDonald, Patricia; Fan, Qing R.

    2016-07-19

    Human calcium-sensing receptor (CaSR) is a G-protein-coupled receptor (GPCR) that maintains extracellular Ca2+homeostasis through the regulation of parathyroid hormone secretion. It functions as a disulfide-tethered homodimer composed of three main domains, the Venus Flytrap module, cysteine-rich domain, and seven-helix transmembrane region. Here, we present the crystal structures of the entire extracellular domain of CaSR in the resting and active conformations. We provide direct evidence that L-amino acids are agonists of the receptor. In the active structure, L-Trp occupies the orthosteric agonist-binding site at the interdomain cleft and is primarily responsible for inducing extracellular domain closure to initiate receptor activation. Our structures reveal multiple binding sites for Ca2+and PO43-ions. Both ions are crucial for structural integrity of the receptor. While Ca2+ions stabilize the active state, PO43-ions reinforce the inactive conformation. The activation mechanism of CaSR involves the formation of a novel dimer interface between subunits.

  16. Kinetic properties of 'dual' orexin receptor antagonists at OX1R and OX2R orexin receptors.

    Directory of Open Access Journals (Sweden)

    Gabrielle Elizabeth Callander

    2013-12-01

    Full Text Available Orexin receptor antagonists represent attractive targets for the development of drugs for the treatment of insomnia. Both efficacy and safety are crucial in clinical settings and thorough investigations of pharmacokinetics and pharmacodynamics can predict contributing factors such as duration of action and undesirable effects. To this end, we studied the interactions between various ‘dual’ orexin receptor antagonists and the orexin receptors, OX1R and OX2R, over time using saturation and competition radioligand binding with [3H]-BBAC ((S-N-([1,1'-biphenyl]-2-yl-1-(2-((1-methyl-1H-benzo[d]imidazol-2-ylthioacetylpyrrolidine-2-carboxamide. In addition, the kinetics of these compounds were investigated in cells expressing human, mouse and rat OX1R and OX2R using FLIPR® assays for calcium accumulation. We demonstrate that almorexant reaches equilibrium very slowly at OX2R, whereas SB-649868, suvorexant and filorexant may take hours to reach steady state at both orexin receptors. By contrast, compounds such as BBAC or the selective OX2R antagonist IPSU ((2-((1H-Indol-3-ylmethyl-9-(4-methoxypyrimidin-2-yl-2,9-diazaspiro[5.5]undecan-1-one bind rapidly and reach equilibrium very quickly in both binding and / or functional assays. Overall, the dual antagonists tested here tend to be rather unselective under non-equilibrium conditions and reach equilibrium very slowly. Once equilibrium is reached, each ligand demonstrates a selectivity profile that is however, distinct from the non-equilibrium condition. The slow kinetics of the dual antagonists tested suggest that in vitro receptor occupancy may be longer lasting than would be predicted. This raises questions as to whether pharmacokinetic studies measuring plasma or brain levels of these antagonists are accurate reflections of receptor occupancy in vivo.

  17. A peptide antagonist of the ErbB1 receptor inhibits receptor activation, tumor cell growth and migration in vitro and xenograft tumor growth in vivo

    DEFF Research Database (Denmark)

    Xu, Ruodan; Povlsen, Gro Klitgaard; Soroka, Vladislav

    2010-01-01

    The epidermal growth factor family of receptor tyrosine kinases (ErbBs) plays essential roles in tumorigenesis and cancer disease progression, and therefore has become an attractive target for structure-based drug design. ErbB receptors are activated by ligand-induced homo- and heterodimerization...... constitutes part of the dimerization arm of ErbB3. Inherbin3 binds to the extracellular domains of all four ErbB receptors, with the lowest peptide binding affinity for ErbB4. Inherbin3 functions as an antagonist of epidermal growth factor (EGF)-ErbB1 signaling. We show that Inherbin3 inhibits EGF-induced Erb....... Structural studies have revealed that ErbB receptor dimers are stabilized by receptor-receptor interactions, primarily mediated by a region in the second extracellular domain, termed the "dimerization arm". The present study is the first biological characterization of a peptide, termed Inherbin3, which...

  18. ALK receptor activation, ligands and therapeutic targeting in glioblastoma and in other cancers

    International Nuclear Information System (INIS)

    Wellstein, Anton

    2012-01-01

    The intracellular anaplastic lymphoma kinase (ALK) fragment shows striking homology with members of the insulin receptor family and was initially identified as an oncogenic fusion protein resulting from a translocation in lymphoma and more recently in a range of cancers. The full-length ALK transmembrane receptor of ~220 kDa was identified based on this initial work. This tyrosine kinase receptor and its ligands, the growth factors pleiotrophin (PTN) and midkine (MK) are highly expressed during development of the nervous system and other organs. Each of these genes has been implicated in malignant progression of different tumor types and shown to alter phenotypes as well as signal transduction in cultured normal and tumor cells. Beyond its role in cancer, the ALK receptor pathway is thought to contribute to nervous system development, function, and repair, as well as metabolic homeostasis and the maintenance of tissue regeneration. ALK receptor activity in cancer can be up-regulated by amplification, overexpression, ligand binding, mutations in the intracellular domain of the receptor and by activity of the receptor tyrosine phosphatase PTPRz. Here we discuss the evidence for ligand control of ALK activity as well as the potential prognostic and therapeutic implications from gene expression and functional studies. An analysis of 18 published gene expression data sets from different cancers shows that overexpression of ALK, its smaller homolog LTK (leukocyte tyrosine kinase) and the ligands PTN and MK in cancer tissues from patients correlate significantly with worse course and outcome of the disease. This observation together with preclinical functional studies suggests that this pathway could be a valid therapeutic target for which complementary targeting strategies with small molecule kinase inhibitors as well as antibodies to ligands or the receptors may be used.

  19. Increased dopamine D1 receptor binding in the human mesocortical system following central cholinergic activation

    International Nuclear Information System (INIS)

    Fedi, M.; Berkovic, S.F.; Tochon-Danguy, H.J.; Reutens, D.C.

    2002-01-01

    Full text: The interaction between the cholinergic and dopaminergic system has been implicated in many pathological processes including, Alzheimer's disease, schizophrenia and drug addiction. Little is known about the control of dopamine (DA) release following central cholinergic activation in humans, but experimental studies suggest that endogenously released Acetylcholine (ACh) achieved by the administration of cholinesterase inhibitors, can increase dopamine efflux in different regions of the brain. This leads to the activation of different types of post-synaptic dopaminergic receptors which belong to the family of G-protein coupled receptors (GPCRs). A common paradigm of the GPCRs desensitization is that agonist-induced receptor signaling is rapidly attenuated by receptor internalisation. Several experiments have shown that the activation of Dl receptors in acute conditions leads, within minutes, to translocation of the receptor from the surface of the neurons to the endosomal compartment in the cytoplasm and increased receptor turnover. To assess changes in Dl receptor density following an intravenous infusion of the selective cholinesterase inhibitor physostigmine salicylate (PHY), we studied eleven normal subjects (10 male and 1 female, mean age 36.1 and 61617; 9.9) using [11C]-SCH23390 and PET The binding potential (BP) for SCH23390 was significantly (p 0.05). There was no statistically significant difference between baseline and physostigmine Kl ratio (p>0.05) suggesting that BP changes observed were not secondary to regional blood flow changes or to an order effect of the scans. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

  20. 5-HT1A receptors modulate small-conductance Ca2+-activated K+ channels

    DEFF Research Database (Denmark)

    Grunnet, Morten; Jespersen, Thomas; Perrier, Jean-François

    2004-01-01

    Small-conductance calcium-activated potassium channels (SK) are responsible for the medium afterhyperpolarisation (mAHP) following action potentials in neurons. Here we tested the ability of serotonin (5-HT) to modulate the activity of SK channels by coexpressing 5-HT1A receptors with different...

  1. Protease-activated receptor-1 impairs host defense in murine pneumococcal pneumonia: a controlled laboratory study

    NARCIS (Netherlands)

    Schouten, Marcel; van't Veer, Cornelis; Roelofs, Joris J. T. H.; Levi, Marcel; van der Poll, Tom

    2012-01-01

    Streptococcus pneumoniae is the most common causative pathogen in community-acquired pneumonia. Protease-activated receptor-1 (PAR-1) is expressed by multiple cell types present in the lungs and can be activated by various proteases generated during acute inflammation. The cellular effect of PAR-1

  2. Morphine withdrawal enhances constitutive μ-opioid receptor activity in the ventral tegmental area

    NARCIS (Netherlands)

    Meye, F.J.; van Zessen, R.; Smidt, M.P.; Adan, R.A.H.; Ramakers, G.M.J.

    2012-01-01

    μ-opioid receptors (MORs) in the ventral tegmental area (VTA) are pivotally involved in addictive behavior. While MORs are typically activated by opioids, they can also become constitutively active in the absence of any agonist. In the current study, we present evidence that MOR constitutive

  3. Prediction of in vitro and in vivo oestrogen receptor activity using hierarchical clustering

    Science.gov (United States)

    In this study, hierarchical clustering classification models were developed to predict in vitro and in vivo oestrogen receptor (ER) activity. Classification models were developed for binding, agonist, and antagonist in vitro ER activity and for mouse in vivo uterotrophic ER bindi...

  4. Identification of a second putative receptor of platelet activating factor on human polymorphonuclear leukocytes

    International Nuclear Information System (INIS)

    Hwang, S.B.

    1987-01-01

    Due to multiple molecular species of platelet activating factor (PAF) and the existence of high affinity binding sites in a variety of cells and tissues, possible existence of PAF receptor subtypes has been suggested. This report shows differences between specific PAF receptors on human leukocytes and platelets. Human PMN leukocyte membranes showed high affinity binding sites for PAF with an equilibrium dissociation constant (Kd) of 4.7 (+/- 1.4) x 10 -10 M. The maximal number (B/sub max/) of receptor sites was estimated to be 3.13 (+/- 1.4) x 10 -13 mol/mg protein. They compared the relative potencies of several PAF agonists and receptor antagonists between human platelet and human leukocyte membranes. One antagonist (Ono-6240) was found to be 8 times less potent at inhibiting the [ 3 H]PAF specific receptor binding to human leukocytes than to human platelets. Mg 2+ , Ca 2+ and K + ions potentiated the [ 3 H]PAF specific binding in both systems. Na + ions inhibited the [ 3 H]PAF specific binding to human platelets but showed no effects in human leukocytes. K + ions decreased the Mg 2+ -potentiated [ 3 H]PAF binding in human leukocytes but showed no effects in human platelets. These results suggest that the PAF specific receptors in human leukocytes are different structurally and possibly functionally from the receptors identified in human platelets

  5. Peroxisome proliferator-activated receptor α activation induces hepatic steatosis, suggesting an adverse effect.

    Directory of Open Access Journals (Sweden)

    Fang Yan

    Full Text Available Non-alcoholic fatty liver disease (NAFLD is characterized by hepatic triglyceride accumulation, ranging from steatosis to steatohepatitis and cirrhosis. NAFLD is a risk factor for cardiovascular diseases and is associated with metabolic syndrome. Antihyperlipidemic drugs are recommended as part of the treatment for NAFLD patients. Although fibrates activate peroxisome proliferator-activated receptor α (PPARα, leading to the reduction of serum triglyceride levels, the effects of these drugs on NAFLD remain controversial. Clinical studies have reported that PPARα activation does not improve hepatic steatosis. In the present study, we focused on exploring the effect and mechanism of PPARα activation on hepatic triglyceride accumulation and hepatic steatosis. Male C57BL/6J mice, Pparα-null mice and HepG2 cells were treated with fenofibrate, one of the most commonly used fibrate drugs. Both low and high doses of fenofibrate were administered. Hepatic steatosis was detected through oil red O staining and electron microscopy. Notably, in fenofibrate-treated mice, the serum triglyceride levels were reduced and the hepatic triglyceride content was increased in a dose-dependent manner. Oil red O staining of liver sections demonstrated that fenofibrate-fed mice accumulated abundant neutral lipids. Fenofibrate also increased the intracellular triglyceride content in HepG2 cells. The expression of sterol regulatory element-binding protein 1c (SREBP-1c and the key genes associated with lipogenesis were increased in fenofibrate-treated mouse livers and HepG2 cells in a dose-dependent manner. However, the effect was strongly impaired in Pparα-null mice treated with fenofibrate. Fenofibrate treatment induced mature SREBP-1c expression via the direct binding of PPARα to the DR1 motif of the SREBP-1c gene. Taken together, these findings indicate the molecular mechanism by which PPARα activation increases liver triglyceride accumulation and suggest an

  6. Dithiothreitol activation of the insulin receptor/kinase does not involve subunit dissociation of the native α2β2 insulin receptor subunit complex

    International Nuclear Information System (INIS)

    Sweet, L.J.; Wilden, P.A.; Pessin, J.E.

    1986-01-01

    The subunit composition of the dithiothreitol- (DTT) activated insulin receptor/kinase was examined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and gel filtration chromatography under denaturing or nondenaturing conditions. Pretreatment of 32 P-labeled insulin receptors with 50 mM DTT followed by gel filtration chromatography in 0.1% SDS demonstrated the dissociation of the α 2 β 2 insulin receptor complex (M/sub r/ 400,000) into the monomeric 95,000 β subunit. In contrast, pretreatment of the insulin receptors with 1-50 mM DTT followed by gel filtration chromatography in 0.1% Triton X-100 resulted in no apparent alteration in mobility compared to the untreated insulin receptors. Resolution of this complex by nonreducing SDS-polyacrylamide gel electrophoresis and autoradiography demonstrated the existence of the α 2 β 2 heterotetrameric complex with essentially no αβ heterodimeric or free monomeric β subunit species present. This suggests that the insulin receptor can reoxidize into the M/sub r/ 400,000 complex after the removal of DTT by gel filtration chromatography. To prevent reoxidation, the insulin receptors were pretreated with 50 mM DTT. Under the conditions the insulin receptors migrated as the M/sub r/ 400,000 α 2 β 2 complex. These results demonstrate that treatment of the insulin receptors with high concentrations of DTT, followed by removal of DTT by gel filtration, results in reoxidation of the reduced α 2 β 2 insulin receptor complex. Further, these results document that although the DTT stimulation of the insulin receptor/kinase does involve reduction of the insulin receptor subunits, it does not result in dissociation of the native α 2 β 2 insulin receptor subunit complex

  7. Protection against methamphetamine-induced neurotoxicity to neostriatal dopaminergic neurons by adenosine receptor activation.

    Science.gov (United States)

    Delle Donne, K T; Sonsalla, P K

    1994-12-01

    Methamphetamine (METH)-induced neurotoxicity to nigrostriatal dopaminergic neurons in experimental animals appears to have a glutamatergic component because blockade of N-methyl-D-aspartate receptors prevents the neuropathologic consequences. Because adenosine affords neuroprotection against various forms of glutamate-mediated neuronal damage, the present studies were performed to investigate whether adenosine plays a protective role in METH-induced toxicity. METH-induced decrements in neostriatal dopamine content and tyrosine hydroxylase activity in mice were potentiated by concurrent treatment with caffeine, a nonselective adenosine antagonist that blocks both A1 and A2 adenosine receptors. In contrast, chronic treatment of mice with caffeine through their drinking water for 4 weeks, which increased the number of adenosine A1 receptors in the neostriatum and frontal cortex, followed by drug washout, prevented the neurochemical changes produced by the treatment of mice with METH treatment. In contrast, this treatment did not prevent 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine-induced dopaminergic neurotoxicity. Furthermore, concurrent administration of cyclopentyladenosine, an adenosine A1 receptor agonist, attenuated the METH-induced neurochemical changes. This protection by cyclopentyladenosine was blocked by cyclopentyltheophylline, an A1 receptor antagonist. These results indicate that activation of A1 receptors can protect against METH-induced neurotoxicity in mice.

  8. Castor oil induces laxation and uterus contraction via ricinoleic acid activating prostaglandin EP3 receptors.

    Science.gov (United States)

    Tunaru, Sorin; Althoff, Till F; Nüsing, Rolf M; Diener, Martin; Offermanns, Stefan

    2012-06-05

    Castor oil is one of the oldest drugs. When given orally, it has a laxative effect and induces labor in pregnant females. The effects of castor oil are mediated by ricinoleic acid, a hydroxylated fatty acid released from castor oil by intestinal lipases. Despite the wide-spread use of castor oil in conventional and folk medicine, the molecular mechanism by which ricinoleic acid acts remains unknown. Here we show that the EP(3) prostanoid receptor is specifically activated by ricinoleic acid and that it mediates the pharmacological effects of castor oil. In mice lacking EP(3) receptors, the laxative effect and the uterus contraction induced via ricinoleic acid are absent. Although a conditional deletion of the EP(3) receptor gene in intestinal epithelial cells did not affect castor oil-induced diarrhea, mice lacking EP(3) receptors only in smooth-muscle cells were unresponsive to this drug. Thus, the castor oil metabolite ricinoleic acid activates intestinal and uterine smooth-muscle cells via EP(3) prostanoid receptors. These findings identify the cellular and molecular mechanism underlying the pharmacological effects of castor oil and indicate a role of the EP(3) receptor as a target to induce laxative effects.

  9. Mechanisms of integrin-vascular endothelial growth factor receptor cross-activation in angiogenesis.

    Science.gov (United States)

    Mahabeleshwar, Ganapati H; Feng, Weiyi; Reddy, Kumar; Plow, Edward F; Byzova, Tatiana V

    2007-09-14

    The functional responses of endothelial cells are dependent on signaling from peptide growth factors and the cellular adhesion receptors, integrins. These include cell adhesion, migration, and proliferation, which, in turn, are essential for more complex processes such as formation of the endothelial tube network during angiogenesis. This study identifies the molecular requirements for the cross-activation between beta3 integrin and tyrosine kinase receptor 2 for vascular endothelial growth factor (VEGF) receptor (VEGFR-2) on endothelium. The relationship between VEGFR-2 and beta3 integrin appears to be synergistic, because VEGFR-2 activation induces beta3 integrin tyrosine phosphorylation, which, in turn, is crucial for VEGF-induced tyrosine phosphorylation of VEGFR-2. We demonstrate here that adhesion- and growth factor-induced beta3 integrin tyrosine phosphorylation are directly mediated by c-Src. VEGF-stimulated recruitment and activation of c-Src and subsequent beta3 integrin tyrosine phosphorylation are critical for interaction between VEGFR-2 and beta3 integrin. Moreover, c-Src mediates growth factor-induced beta3 integrin activation, ligand binding, beta3 integrin-dependent cell adhesion, directional migration of endothelial cells, and initiation of angiogenic programming in endothelial cells. Thus, the present study determines the molecular mechanisms and consequences of the synergism between 2 cell surface receptor systems, growth factor receptor and integrins, and opens new avenues for the development of pro- and antiangiogenic strategies.

  10. Receptor-mediated endocytosis generates nanomechanical force reflective of ligand identity and cellular property.

    Science.gov (United States)

    Zhang, Xiao; Ren, Juan; Wang, Jingren; Li, Shixie; Zou, Qingze; Gao, Nan

    2018-08-01

    Whether environmental (thermal, chemical, and nutrient) signals generate quantifiable, nanoscale, mechanophysical changes in the cellular plasma membrane has not been well elucidated. Assessment of such mechanophysical properties of plasma membrane may shed lights on fundamental cellular process. Atomic force microscopic (AFM) measurement of the mechanical properties of live cells was hampered by the difficulty in accounting for the effects of the cantilever motion and the associated hydrodynamic force on the mechanical measurement. These challenges have been addressed in our recently developed control-based AFM nanomechanical measurement protocol, which enables a fast, noninvasive, broadband measurement of the real-time changes in plasma membrane elasticity in live cells. Here we show using this newly developed AFM platform that the plasma membrane of live mammalian cells exhibits a constant and quantifiable nanomechanical property, the membrane elasticity. This mechanical property sensitively changes in response to environmental factors, such as the thermal, chemical, and growth factor stimuli. We demonstrate that different chemical inhibitors of endocytosis elicit distinct changes in plasma membrane elastic modulus reflecting their specific molecular actions on the lipid configuration or the endocytic machinery. Interestingly, two different growth factors, EGF and Wnt3a, elicited distinct elastic force profiles revealed by AFM at the plasma membrane during receptor-mediated endocytosis. By applying this platform to genetically modified cells, we uncovered a previously unknown contribution of Cdc42, a key component of the cellular trafficking network, to EGF-stimulated endocytosis at plasma membrane. Together, this nanomechanical AFM study establishes an important foundation that is expandable and adaptable for investigation of cellular membrane evolution in response to various key extracellular signals. © 2017 Wiley Periodicals, Inc.

  11. Activation of Toll-like receptors nucleates assembly of the MyDDosome signaling hub.

    Science.gov (United States)

    Latty, Sarah Louise; Sakai, Jiro; Hopkins, Lee; Verstak, Brett; Paramo, Teresa; Berglund, Nils A; Cammorota, Eugenia; Cicuta, Pietro; Gay, Nicholas J; Bond, Peter J; Klenerman, David; Bryant, Clare E

    2018-01-24

    Infection and tissue damage induces assembly of supramolecular organizing centres (SMOCs)), such as the Toll-like receptor (TLR) MyDDosome, to co-ordinate inflammatory signaling. SMOC assembly is thought to drive digital all-or-none responses, yet TLR activation by diverse microbes induces anything from mild to severe inflammation. Using single-molecule imaging of TLR4-MyDDosome signaling in living macrophages, we find that MyDDosomes assemble within minutes of TLR4 stimulation. TLR4/MD2 activation leads only to formation of TLR4/MD2 heterotetramers, but not oligomers, suggesting a stoichiometric mismatch between activated receptors and MyDDosomes. The strength of TLR4 signalling depends not only on the number and size of MyDDosomes formed but also how quickly these structures assemble. Activated TLR4, therefore, acts transiently nucleating assembly of MyDDosomes, a process that is uncoupled from receptor activation. These data explain how the oncogenic mutation of MyD88 (L265P) assembles MyDDosomes in the absence of receptor activation to cause constitutive activation of pro-survival NF-κB signalling. © 2018, Latty et al.

  12. Communication over the network of binary switches regulates the activation of A2A adenosine receptor.

    Directory of Open Access Journals (Sweden)

    Yoonji Lee

    2015-02-01

    Full Text Available Dynamics and functions of G-protein coupled receptors (GPCRs are accurately regulated by the type of ligands that bind to the orthosteric or allosteric binding sites. To glean the structural and dynamical origin of ligand-dependent modulation of GPCR activity, we performed total ~ 5 μsec molecular dynamics simulations of A2A adenosine receptor (A2AAR in its apo, antagonist-bound, and agonist-bound forms in an explicit water and membrane environment, and examined the corresponding dynamics and correlation between the 10 key structural motifs that serve as the allosteric hotspots in intramolecular signaling network. We dubbed these 10 structural motifs "binary switches" as they display molecular interactions that switch between two distinct states. By projecting the receptor dynamics on these binary switches that yield 2(10 microstates, we show that (i the receptors in apo, antagonist-bound, and agonist-bound states explore vastly different conformational space; (ii among the three receptor states the apo state explores the broadest range of microstates; (iii in the presence of the agonist, the active conformation is maintained through coherent couplings among the binary switches; and (iv to be most specific, our analysis shows that W246, located deep inside the binding cleft, can serve as both an agonist sensor and actuator of ensuing intramolecular signaling for the receptor activation. Finally, our analysis of multiple trajectories generated by inserting an agonist to the apo state underscores that the transition of the receptor from inactive to active form requires the disruption of ionic-lock in the DRY motif.

  13. Endothelin receptors and activity differ in human, dog, and rabbit lung.

    Science.gov (United States)

    McKay, K O; Armour, C L; Black, J L

    1996-01-01

    In this study, we have examined dog and rabbit airways as potential models for human airways in regard to the activity of endothelin. The receptors involved in the response to endothelin-1 (ET-1) in airway tissue from human, rabbit, and dog lung were investigated, as was the mechanism responsible for the contraction to ET-1 in tissue from the three species. By using specific endothelin receptor agonists and antagonists, we have demonstrated that ETB receptors predominate in rabbit and human airways and ETA receptors in dog airways. The contraction to ET-1 is not dependent on cyclooxygenase products of arachidonic acid, as indomethacin had no effect on the response to ET-1. Extracellular calcium influx via voltage-dependent channels is necessary for contraction to ET-1 in rabbit and dog airways. These results are in contrast to our previously reported results in human airways, in which neither removal of extracellular calcium nor verapamil affected the ET-1 response. The sustained phase of the contraction to ET-1 in all three species may be mediated in part by activation of protein kinase C (PKC), as the inhibitor staurosporine significantly altered the time course of the response to endothelin. We therefore conclude that in rabbit airways ET-1 activates ETB receptors, triggers the influx of extracellular calcium through voltage-dependent channels, and induces a contractile response that is, in part, dependent upon stimulation of PKC. The same mechanism is triggered in dog bronchus; however, the receptors involved in this species are of the ETA type. Finally, in human airways, the contractile response to ET-1, while independent of extracellular calcium influx, is dependent upon PKC activation after binding of the peptide to ETB receptors.

  14. Structure of the Nanobody-Stabilized Active State of the Kappa Opioid Receptor.

    Science.gov (United States)

    Che, Tao; Majumdar, Susruta; Zaidi, Saheem A; Ondachi, Pauline; McCorvy, John D; Wang, Sheng; Mosier, Philip D; Uprety, Rajendra; Vardy, Eyal; Krumm, Brian E; Han, Gye Won; Lee, Ming-Yue; Pardon, Els; Steyaert, Jan; Huang, Xi-Ping; Strachan, Ryan T; Tribo, Alexandra R; Pasternak, Gavril W; Carroll, F Ivy; Stevens, Raymond C; Cherezov, Vadim; Katritch, Vsevolod; Wacker, Daniel; Roth, Bryan L

    2018-01-11

    The κ-opioid receptor (KOP) mediates the actions of opioids with hallucinogenic, dysphoric, and analgesic activities. The design of KOP analgesics devoid of hallucinatory and dysphoric effects has been hindered by an incomplete structural and mechanistic understanding of KOP agonist actions. Here, we provide a crystal structure of human KOP in complex with the potent epoxymorphinan opioid agonist MP1104 and an active-state-stabilizing nanobody. Comparisons between inactive- and active-state opioid receptor structures reveal substantial conformational changes in the binding pocket and intracellular and extracellular regions. Extensive structural analysis and experimental validation illuminate key residues that propagate larger-scale structural rearrangements and transducer binding that, collectively, elucidate the structural determinants of KOP pharmacology, function, and biased signaling. These molecular insights promise to accelerate the structure-guided design of safer and more effective κ-opioid receptor therapeutics. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Activation of the Ca2+-sensing receptors increases currents through inward rectifier K+ channels via activation of phosphatidylinositol 4-kinase

    OpenAIRE

    Liu, Chung-Hung; Chang, Hsueh-Kai; Lee, Sue-Ping; Shieh, Ru-Chi

    2016-01-01

    Inward rectifier K+ channels are important for maintaining normal electrical function in many cell types. The proper function of these channels requires the presence of membrane phosphoinositide 4,5-bisphosphate (PIP2). Stimulation of the Ca2+-sensing receptor CaR, a pleiotropic G protein-coupled receptor, activates both Gq/11, which decreases PIP2, and phosphatidylinositol 4-kinase (PI-4-K), which, conversely, increases PIP2. How membrane PIP2 levels are regulated by CaR activation and wheth...

  16. Conditioned place preference and locomotor activity in response to methylphenidate, amphetamine and cocaine in mice lacking dopamine D4 receptors

    Energy Technology Data Exchange (ETDEWEB)

    Thanos, P.K.; Thanos, P.K.; Bermeo, C.; Rubinstein, M.; Suchland, K.L.; Wang, G.-J.; Grandy, D.K.; Volkow, N.D.

    2010-05-01

    Methylphenidate (MP) and amphetamine (AMPH) are the most frequently prescribed medications for the treatment of attention-deficit/hyperactivity disorder (ADHD). Both drugs are believed to derive their therapeutic benefit by virtue of their dopamine (DA)-enhancing effects, yet an explanation for the observation that some patients with ADHD respond well to one medication but not to the other remains elusive. The dopaminergic effects of MP and AMPH are also thought to underlie their reinforcing properties and ultimately their abuse. Polymorphisms in the human gene that codes for the DA D4 receptor (D4R) have been repeatedly associated with ADHD and may correlate with the therapeutic as well as the reinforcing effects of responses to these psychostimulant medications. Conditioned place preference (CPP) for MP, AMPH and cocaine were evaluated in wild-type (WT) mice and their genetically engineered littermates, congenic on the C57Bl/6J background, that completely lack D4Rs (knockout or KO). In addition, the locomotor activity in these mice during the conditioning phase of CPP was tested in the CPP chambers. D4 receptor KO and WT mice showed CPP and increased locomotor activity in response to each of the three psychostimulants tested. D4R differentially modulates the CPP responses to MP, AMPH and cocaine. While the D4R genotype affected CPP responses to MP (high dose only) and AMPH (low dose only) it had no effects on cocaine. Inasmuch as CPP is considered an indicator of sensitivity to reinforcing responses to drugs these data suggest a significant but limited role of D4Rs in modulating conditioning responses to MP and AMPH. In the locomotor test, D4 receptor KO mice displayed attenuated increases in AMPH-induced locomotor activity whereas responses to cocaine and MP did not differ. These results suggest distinct mechanisms for D4 receptor modulation of the reinforcing (perhaps via attenuating dopaminergic signalling) and locomotor properties of these stimulant drugs

  17. Activity-dependent control of NMDA receptor subunit composition at hippocampal mossy fibre synapses.

    Science.gov (United States)

    Carta, Mario; Srikumar, Bettadapura N; Gorlewicz, Adam; Rebola, Nelson; Mulle, Christophe

    2018-02-15

    CA3 pyramidal cells display input-specific differences in the subunit composition of synaptic NMDA receptors (NMDARs). Although at low density, GluN2B contributes significantly to NMDAR-mediated EPSCs at mossy fibre synapses. Long-term potentiation (LTP) of NMDARs triggers a modification in the subunit composition of synaptic NMDARs by insertion of GluN2B. GluN2B subunits are essential for the expression of LTP of NMDARs at mossy fibre synapses. Single neurons express NMDA receptors (NMDARs) with distinct subunit composition and biophysical properties that can be segregated in an input-specific manner. The dynamic control of the heterogeneous distribution of synaptic NMDARs is crucial to control input-dependent synaptic integration and plasticity. In hippocampal CA3 pyramidal cells from mice of both sexes, we found that mossy fibre (MF) synapses display a markedly lower proportion of GluN2B-containing NMDARs than associative/commissural synapses. The mechanism involved in such heterogeneous distribution of GluN2B subunits is not known. Here we show that long-term potentiation (LTP) of NMDARs, which is selectively expressed at MF-CA3 pyramidal cell synapses, triggers a modification in the subunit composition of synaptic NMDARs by insertion of GluN2B. This activity-dependent recruitment of GluN2B at mature MF-CA3 pyramidal cell synapses contrasts with the removal of GluN2B subunits at other glutamatergic synapses during development and in response to activity. Furthermore, although expressed at low levels, GluN2B is necessary for the expression of LTP of NMDARs at MF-CA3 pyramidal cell synapses. Altogether, we reveal a previously unknown activity-dependent regulation and function of GluN2B subunits that may contribute to the heterogeneous plasticity induction rules in CA3 pyramidal cells. © 2017 Centre Nationnal de la Recherche Scientifique. The Journal of Physiology © 2017 The Physiological Society.

  18. Serotoninergic receptors in brain tissue: properties and identification of various 3H-ligand binding sites in vitro

    International Nuclear Information System (INIS)

    Leysen, J.E.

    1981-01-01

    In vitro binding studies to serotoninergic receptors were performed using 3 H-LSD, 3 H-5-HT and 3 H-spiperone. An overwiew is given on findings using these three ligands with respect to the following: localization of specific binding sites, in various animal species, the regional distribution in the brain and periphery, the subcellular and cellular distribution. Properties of the binding sites, influence of the composition of the assay medium, binding kinetic properties, receptor regulation in vivo. Identity of the binding sites, differences between site for various 3 H-ligands, pharmacological specificity of the membranous binding sites, chemical composition of the macromolecular complex constituting the binding site. Function of the receptor. Binding affinities of 44 compounds were measured in binding assays using 3 H-spiperone and 3 H-LSD with rat frontal cortex membrane preparations and using 3 H-5-HT and 3 H-LSD with rat hippocampal membrane preparations

  19. Pancreatic acini possess endothelin receptors whose internalization is regulated by PLC-activating agents.

    Science.gov (United States)

    Hildebrand, P; Mrozinski, J E; Mantey, S A; Patto, R J; Jensen, R T

    1993-05-01

    Endothelin-1 (ET-1) and ET-3 mRNA have been found in the pancreas. We investigated the ability of ET-1, ET-2, and ET-3 to interact with and alter dispersed rat pancreatic acinar cell function. Radiolabeled ETs bound in a time- and temperature-dependent fashion, which was specific and saturable. Analysis demonstrated two classes of receptors, one class (ETA receptor) had a high affinity for ET-1 but a low affinity for ET-3, and the other class (ETB receptor) had equally high affinities for ET-1 and ET-3. No specific receptor for ET-2 was identified. Pancreatic secretagogues that activate phospholipase C (PLC) inhibited binding of 125I-labeled ET-1 (125I-ET-1) or 125I-ET-3, whereas agents that act through adenosine 3',5'-cyclic monophosphate (cAMP) did not. A23187 had no effect on 125I-ET-1 or 125I-ET-3 binding, whereas the phorbol ester 12-O-tetradecanoylphorbol 13-acetate reduced binding. The effect of cholecystokinin octapeptide (CCK-8) was mediated through its own receptor. Stripping of surface bound ligand studies demonstrated that both 125I-labeled ET-1 and 125I-labeled ET-3 were rapidly internalized. CCK-8 decreased the internalization but did not change the amount of surface bound ligand. Endothelins neither stimulate nor alter changes in enzyme secretion, intracellular calcium, cAMP, or [3H]inositol trisphosphate (IP3). This study demonstrates the presence of ETA and ETB receptors on rat pancreatic acini; occupation of both receptors resulted in rapid internalization, which is regulated by PLC-activating secretagogues. Occupation of either ET receptor did not alter intracellular calcium, cAMP, IP3, or stimulate amylase release.

  20. Activated prostaglandin D2 receptors on macrophages enhance neutrophil recruitment into the lung

    Science.gov (United States)

    Jandl, Katharina; Stacher, Elvira; Bálint, Zoltán; Sturm, Eva Maria; Maric, Jovana; Peinhaupt, Miriam; Luschnig, Petra; Aringer, Ida; Fauland, Alexander; Konya, Viktoria; Dahlen, Sven-Erik; Wheelock, Craig E.; Kratky, Dagmar; Olschewski, Andrea; Marsche, Gunther; Schuligoi, Rufina; Heinemann, Akos

    2016-01-01

    Background Prostaglandin (PG) D2 is an early-phase mediator in inflammation, but its action and the roles of the 2 D-type prostanoid receptors (DPs) DP1 and DP2 (also called chemoattractant receptor–homologous molecule expressed on TH2 cells) in regulating macrophages have not been elucidated to date. Objective We investigated the role of PGD2 receptors on primary human macrophages, as well as primary murine lung macrophages, and their ability to influence neutrophil action in vitro and in vivo. Methods In vitro studies, including migration, Ca2+ flux, and cytokine secretion, were conducted with primary human monocyte-derived macrophages and neutrophils and freshly isolated murine alveolar and pulmonary interstitial macrophages. In vivo pulmonary inflammation was assessed in male BALB/c mice. Results Activation of DP1, DP2, or both receptors on human macrophages induced strong intracellular Ca2+ flux, cytokine release, and migration of macrophages. In a murine model of LPS-induced pulmonary inflammation, activation of each PGD2 receptor resulted in aggravated airway neutrophilia, tissue myeloperoxidase activity, cytokine contents, and decreased lung compliance. Selective depletion of alveolar macrophages abolished the PGD2-enhanced inflammatory response. Activation of PGD2 receptors on human macrophages enhanced the migratory capacity and prolonged the survival of neutrophils in vitro. In human lung tissue specimens both DP1 and DP2 receptors were located on alveolar macrophages along with hematopoietic PGD synthase, the rate-limiting enzyme of PGD2 synthesis. Conclusion For the first time, our results show that PGD2 markedly augments disease activity through its ability to enhance the proinflammatory actions of macrophages and subsequent neutrophil activation. PMID:26792210

  1. Covalent modification of mutant rat P2X2 receptors with a thiol-reactive fluorophore allows channel activation by zinc or acidic pH without ATP.

    Directory of Open Access Journals (Sweden)

    Shlomo S Dellal

    Full Text Available Rat P2X2 receptors open at an undetectably low rate in the absence of ATP. Furthermore, two allosteric modulators, zinc and acidic pH, cannot by themselves open these channels. We describe here the properties of a mutant receptor, K69C, before and after treatment with the thiol-reactive fluorophore Alexa Fluor 546 C(5-maleimide (AM546. Xenopus oocytes expressing unmodified K69C were not activated under basal conditions nor by 1,000 µM ATP. AM546 treatment caused a small increase in the inward holding current which persisted on washout and control experiments demonstrated this current was due to ATP independent opening of the channels. Following AM546 treatment, zinc (100 µM or acidic external solution (pH 6.5 elicited inward currents when applied without any exogenous ATP. In the double mutant K69C/H319K, zinc elicited much larger inward currents, while acidic pH generated outward currents. Suramin, which is an antagonist of wild type receptors, behaved as an agonist at AM546-treated K69C receptors. Several other cysteine-reactive fluorophores tested on K69C did not cause these changes. These modified receptors show promise as a tool for studying the mechanisms of P2X receptor activation.

  2. Glucocorticoid receptor modulators.

    Science.gov (United States)

    Meijer, Onno C; Koorneef, Lisa L; Kroon, Jan

    2018-06-01

    The glucocorticoid hormone cortisol acts throughout the body to support circadian processes and adaptation to stress. The glucocorticoid receptor is the target of cortisol and of synthetic glucocorticoids, which are used widely in the clinic. Both agonism and antagonism of the glucocorticoid receptor may be beneficial in disease, but given the wide expression of the receptor and involvement in various processes, beneficial effects are often accompanied by unwanted side effects. Selective glucocorticoid receptor modulators are ligands that induce a receptor conformation that allows activation of only a subset of downstream signaling pathways. Such molecules thereby combine agonistic and antagonistic properties. Here we discuss the mechanisms underlying selective receptor modulation and their promise in treating diseases in several organ systems where cortisol signaling plays a role. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  3. Potentiated antibodies to mu-opiate receptors: effect on integrative activity of the brain.

    Science.gov (United States)

    Geiko, V V; Vorob'eva, T M; Berchenko, O G; Epstein, O I

    2003-01-01

    The effect of homeopathically potentiated antibodies to mu-receptors (10(-100) wt %) on integrative activity of rat brain was studied using the models of self-stimulation of the lateral hypothalamus and convulsions produced by electric current. Electric current was delivered through electrodes implanted into the ventromedial hypothalamus. Single treatment with potentiated antibodies to mu-receptors increased the rate of self-stimulation and decreased the threshold of convulsive seizures. Administration of these antibodies for 7 days led to further activation of the positive reinforcement system and decrease in seizure thresholds. Distilled water did not change the rate of self-stimulation and seizure threshold.

  4. Discoidin domain receptor 1 is activated independently of beta(1) integrin

    DEFF Research Database (Denmark)

    Vogel, W; Brakebusch, C; Fässler, R

    2000-01-01

    independent of the epidermal growth factor (EGF) receptor. In cells that endogenously express both DDR1 and the EGF receptor, stimulation with EGF does not induce DDR activation. Third, we detected full DDR1 activation after collagen stimulation in cells that have been treated with blocking antibodies...... for alpha(2)beta(1) integrin or in cells with a targeted deletion of the beta(1) integrin gene. Finally, we show that overexpression of dominant negative DDR1 in the myoblast cell line C2C12 blocks cellular differentiation and the formation of myofibers....

  5. Similar activation of signal transduction pathways by the herpesvirus-encoded chemokine receptors US28 and ORF74

    DEFF Research Database (Denmark)

    McLean, Katherine A; Holst, Peter J; Martini, Lene

    2004-01-01

    The virally encoded chemokine receptors US28 from human cytomegalovirus and ORF74 from human herpesvirus 8 are both constitutively active. We show that both receptors constitutively activate the transcription factors nuclear factor of activated T cells (NFAT) and cAMP response element binding...

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

    Science.gov (United States)

    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.

  7. Activation of G-proteins by receptor-stimulated nucleoside diphosphate kinase in Dictyostelium.

    Science.gov (United States)

    Bominaar, A A; Molijn, A C; Pestel, M; Veron, M; Van Haastert, P J

    1993-01-01

    Recently, interest in the enzyme nucleoside diphosphate kinase (EC2.7.4.6) has increased as a result of its possible involvement in cell proliferation and development. Since NDP kinase is one of the major sources of GTP in cells, it has been suggested that the effects of an altered NDP kinase activity on cellular processes might be the result of altered transmembrane signal transduction via guanine nucleotide-binding proteins (G-proteins). In the cellular slime mould Dictyostelium discoideum, extracellular cAMP induces an increase of phospholipase C activity via a surface cAMP receptor and G-proteins. In this paper it is demonstrated that part of the cellular NDP kinase is associated with the membrane and stimulated by cell surface cAMP receptors. The GTP produced by the action of NDP kinase is capable of activating G-proteins as monitored by altered G-protein-receptor interaction and the activation of the effector enzyme phospholipase C. Furthermore, specific monoclonal antibodies inhibit the effect of NDP kinase on G-protein activation. These results suggest that receptor-stimulated NDP kinase contributes to the mediation of hormone action by producing GTP for the activation of GTP-binding proteins. Images PMID:8389692

  8. Therapeutic actions of an insulin receptor activator and a novel peroxisome proliferator-activated receptor gamma agonist in the spontaneously hypertensive obese rat model of metabolic syndrome X.

    Science.gov (United States)

    Velliquette, Rodney A; Friedman, Jacob E; Shao, J; Zhang, Bei B; Ernsberger, Paul

    2005-07-01

    Insulin resistance clusters with hyperlipidemia, impaired glucose tolerance, and hypertension as metabolic syndrome X. We tested a low molecular weight insulin receptor activator, demethylasterriquinone B-1 (DMAQ-B1), and a novel indole peroxisome proliferator-activated receptor gamma agonist, 2-(2-(4-phenoxy-2-propylphenoxy)ethyl)indole-5-acetic acid (PPEIA), in spontaneously hypertensive obese rats (SHROB), a genetic model of syndrome X. Agents were given orally for 19 days. SHROB showed fasting normoglycemia but impaired glucose tolerance after an oral load, as shown by increased glucose area under the curve (AUC) [20,700 mg x min/ml versus 8100 in lean spontaneously hypertensive rats (SHR)]. Insulin resistance was indicated by 20-fold excess fasting insulin and increased insulin AUC (6300 ng x min/ml versus 990 in SHR). DMAQ-B1 did not affect glucose tolerance (glucose AUC = 21,300) but reduced fasting insulin 2-fold and insulin AUC (insulin AUC = 4300). PPEIA normalized glucose tolerance (glucose AUC = 9100) and reduced insulin AUC (to 3180) without affecting fasting insulin. PPEIA also increased food intake, fat mass, and body weight gain (81 +/- 12 versus 45 +/- 8 g in untreated controls), whereas DMAQ-B1 had no effect on body weight but reduced subscapular fat mass. PPEIA but not DMAQ-B1 reduced blood pressure. In skeletal muscle, insulin-stimulated phosphorylation of the insulin receptor and insulin receptor substrate protein 1-associated phosphatidylinositol 3-kinase activity were decreased by 40 to 55% in SHROB relative to lean SHR. PPEIA, but not DMAQ-B1, enhanced both insulin actions. SHROB also showed severe hypertriglyceridemia (355 +/- 42 mg/dl versus 65 +/- 3 in SHR) attenuated by both agents (DMAQ-B1, 228 +/- 18; PPEIA, 79 +/- 3). Both these novel antidiabetic agents attenuate insulin resistance and hypertriglyceridemia associated with metabolic syndrome but via distinct mechanisms.

  9. Imaging and measuring the biophysical properties of Fc gamma receptors on single macrophages using atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mi [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, Lianqing, E-mail: lqliu@sia.cn [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China); Xi, Ning [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Hong Kong (China); Wang, Yuechao [State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China); Xiao, Xiubin [Department of Lymphoma, Affiliated Hospital of Military Medical Academy of Sciences, Beijing 100071 (China); Zhang, Weijing, E-mail: zhangwj3072@163.com [Department of Lymphoma, Affiliated Hospital of Military Medical Academy of Sciences, Beijing 100071 (China)

    2013-09-06

    Highlights: •Nanoscale cellular ultra-structures of macrophages were observed. •The binding affinities of FcγRs were measured directly on macrophages. •The nanoscale distributions of FcγRs were mapped on macrophages. -- Abstract: Fc gamma receptors (FcγR), widely expressed on effector cells (e.g., NK cells, macrophages), play an important role in clinical cancer immunotherapy. The binding of FcγRs to the Fc portions of antibodies that are attached to the target cells can activate the antibody-dependent cell-mediated cytotoxicity (ADCC) killing mechanism which leads to the lysis of target cells. In this work, we used atomic force microscopy (AFM) to observe the cellular ultra-structures and measure the biophysical properties (affinity and distribution) of FcγRs on single macrophages in aqueous environments. AFM imaging was used to obtain the topographies of macrophages, revealing the nanoscale cellular fine structures. For molecular interaction recognition, antibody molecules were attached onto AFM tips via a heterobifunctional polyethylene glycol (PEG) crosslinker. With AFM single-molecule force spectroscopy, the binding affinities of FcγRs were quantitatively measured on single macrophages. Adhesion force mapping method was used to localize the FcγRs, revealing the nanoscale distribution of FcγRs on local areas of macrophages. The experimental results can improve our understanding of FcγRs on macrophages; the established approach will facilitate further research on physiological activities involved in antibody-based immunotherapy.

  10. Phasic dopamine release drives rapid activation of striatal D2-receptors

    Science.gov (United States)

    Marcott, Pamela F; Mamaligas, Aphroditi A; Ford, Christopher P

    2014-01-01

    Summary Striatal dopamine transmission underlies numerous goal-directed behaviors. Medium spiny neurons (MSNs) are a major target of dopamine in the striatum. However, as dopamine does not directly evoke a synaptic event in MSNs, the time course of dopamine signaling in these cells remains unclear. To examine how dopamine release activates D2-receptors on MSNs, G-protein activated inwardly rectifying potassium (GIRK2; Kir 3.2) channels were virally overexpressed in the striatum and the resulting outward currents were used as a sensor of D2-receptor activation. Electrical and optogenetic stimulation of dopamine terminals evoked robust D2-receptor inhibitory post-synaptic currents (IPSCs) in GIRK2-expressing MSNs that occurred in under a second. Evoked D2-IPSCs could be driven by repetitive stimulation and were not occluded by background dopamine tone. Together, the results indicate that D2-receptors on MSNs exhibit functional low affinity and suggest that striatal D2-receptors can encode both tonic and phasic dopamine signals. PMID:25242218

  11. The apelin receptor influences biomechanical and morphological properties of endothelial cells.

    Science.gov (United States)

    Strohbach, Anne; Pennewitz, Malte; Glaubitz, Michael; Palankar, Raghavendra; Groß, Stefan; Lorenz, Florian; Materzok, Ilka; Rong, Alena; Busch, Mathias C; Felix, Stephan B; Delcea, Mihaela; Busch, Raila

    2018-08-01

    The adaption of endothelial cells to local flow conditions is a multifunctional process which leads to distinct alterations in cell shape, the subcellular distribution of structural proteins, and cellular function. G-protein-coupled receptors (GPCRs) have been identified to be fundamentally involved in such processes. Recently, we and others have shown that the expression of the endothelial GPCR apelin receptor (APJ) is regulated by fluid flow and that activation of APJ participates in signaling pathways which are related to processes of mechanotransduction. The present study aims to illuminate these findings by further visualization of APJ function. We show that APJ is located to the cellular junctions and might thus be associated with platelet endothelial cell adhesion molecule-1 (PECAM-1) in human umbilical vein endothelial cells (HUVEC). Furthermore, siRNA-mediated silencing of APJ expression influences the shear-induced adaption of HUVEC in terms of cytoskeletal remodeling, cellular elasticity, cellular motility, attachment, and distribution of adhesion complexes. Taken together, our results demonstrate that APJ is crucial for complemented endothelial adaption to local flow conditions. © 2018 Wiley Periodicals, Inc.

  12. Activation of neurotensin receptors and purinoceptors in human colonic adenocarcinoma cells detected with the microphysiometer.

    Science.gov (United States)

    Richards, M; van Giersbergen, P; Zimmermann, A; Lesur, B; Hoflack, J

    1997-10-01

    Activation of endogenous neurotensin (NT) receptors and P2-purinoceptors expressed by human colonic adenocarcinoma HT-29 cells increased extracellular acidification rates that were detected in the microphysiometer. NT (pGlu-Leu-Tyr-Glu-Asn-Lys-Pro-Arg-Arg-Pro-Tyr-Ile-Leu), NT[8-13] (Arg-Arg-Pro-Tyr-Ile-Leu), NT[9-13] (Arg-Pro-Tyr-Ile-Leu), and NT1 (N alpha methyl-Arg-Lys-Pro-Trp-Tle-Leu [Tle = tert-leucine]) were full agonists, whereas XL 775 (N-[N-[2-[3-[[6-amino-1-oxo-2-[[(phenylmethoxy)carbonyl]-amino]hex yl]amino]phenyl]-3-(4-hydroxyphenyl)-1-oxo-2-propenyl]-L-isoleucyl]-L-le ucine) was a partial agonist for activating NT receptors expressed by HT-29 cells. Desensitization induced by NT was rapid and monophasic with 85% of the initial response lost by a 30-s exposure. Once initiated, the rate and extent of desensitization were similar for different concentrations of a given agonist, for agonists of different potencies, and for agonists of different efficacies, which suggests that desensitization may be independent of receptor occupancy or agonist efficacy. Resensitization was a much slower process, requiring 60 min before the full agonist response to NT was recovered. ATP, via P2-purinoceptors, also activated cellular acidification rates in a concentration-dependent manner. ATP induced a biphasic desensitization of purinoceptors with a loss of ca. 50% of the initial stimulation detectable between 30 and 90 s of exposure to the agonist. Desensitization of NT receptors did not influence the activation of P2-purinoceptors by ATP, suggesting there was no heterologous desensitization between the two types of receptors. Superfusion with NT receptor agonists for 15 min at concentrations that did not elicit changes in extracellular acidification rates blocked, in a concentration-dependent manner, the agonist response induced by 100 nM NT. This may reflect sequestration of the receptor. These results suggest that the high agonist affinity state of NT receptors may

  13. The 5HT(1A) receptor ligand, S15535, antagonises G-protein activation: a [35S]GTPgammaS and [3H]S15535 autoradiography study.

    Science.gov (United States)

    Newman-Tancredi, A; Rivet, J; Chaput, C; Touzard, M; Verrièle, L; Millan, M J

    1999-11-19

    4-(Benzodioxan-5-yl)1-(indan-2-yl)piperazine (S15535) is a highly selective ligand at 5-HT(1A) receptors. The present study compared its autoradiographic labelling of rat brain sections with its functional actions, visualised by guanylyl-5'-[gamma-thio]-triphosphate ([35S]GTPgammaS) autoradiography, which affords a measure of G-protein activation. [3H]S15535 binding was highest in hippocampus, frontal cortex, entorhinal cortex, lateral septum, interpeduncular nucleus and dorsal raphe, consistent with specific labelling of 5-HT(1A) receptors. In functional studies, S15535 (10 microM) did not markedly stimulate G-protein activation in any brain region, but abolished the activation induced by the selective 5-HT(1A) agonist, (+)-8-hydroxy-dipropyl-aminotetralin ((+)-8-OH-DPAT, 1 microM), in structures enriched in [3H]S15535 labelling. S15535 did not block 5-HT-stimulated activation in caudate nucleus or substantia nigra, regions where (+)-8-OH-DPAT was ineffective and [3H]S15535 binding was absent. Interestingly, S15535 attenuated (+)-8-OH-DPAT and 5-HT-stimulated G-protein activation in dorsal raphe, a region in which S15535 is known to exhibit agonist properties in vivo [Lejeune, F., Millan, M.J., 1998. Induction of burst firing in ventral tegmental area dopaminergic neurons by activation of serotonin (5-HT)(1A) receptors: WAY100,635-reversible actions of the highly selective ligands, flesinoxan and S15535. Synapse 30, 172-180.]. The present data show that (i) [3H]S15535 labels pre- and post-synaptic populations of 5-HT(1A) sites in rat brain sections, (ii) S15535 exhibits antagonist properties at post-synaptic 5-HT(1A) receptors in corticolimbic regions, and (iii) S15535 also attenuates agonist-stimulated G-protein activation at raphe-localised 5-HT(1A) receptors.

  14. GABAA receptors in visual and auditory cortex and neural activity changes during basic visual stimulation

    Directory of Open Access Journals (Sweden)

    Pengmin eQin

    2012-12-01

    Full Text Available Recent imaging studies have demonstrated that levels of resting GABA in the visual cortex predict the degree of stimulus-induced activity in the same region. These studies have used the presentation of discrete visual stimulus; the change from closed eyes to open also represents a simple visual stimulus, however, and has been shown to induce changes in local brain activity and in functional connectivity between regions. We thus aimed to investigate the role of the GABA system, specifically GABAA receptors, in the changes in brain activity between the eyes closed (EC and eyes open (EO state in order to provide detail at the receptor level to complement previous studies of GABA concentrations. We conducted an fMRI study involving two different modes of the change from EC to EO: An EO and EC block design, allowing the modelling of the haemodynamic response, followed by longer periods of EC and EO to allow the measuring of functional connectivity. The same subjects also underwent [18F]Flumazenil PET measure GABAA receptor binding potentials. It was demonstrated that the local-to-global ratio of GABAA receptor binding potential in the visual cortex predicted the degree of changes in neural activity from EC to EO. This same relationship was also shown in the auditory cortex. Furthermore, the local-to-global ratio of GABAA receptor binding potential in the visual cortex also predicts the change of functional connectivity between visual and auditory cortex from EC to EO. These findings contribute to our understanding of the role of GABAA receptors in stimulus-induced neural activity in local regions and in inter-regional functional connectivity.

  15. Accessibility of receptor-bound urokinase to type-1 plasminogen activator inhibitor

    Energy Technology Data Exchange (ETDEWEB)

    Cubellis, M.V.; Andreasen, P.; Ragno, P.; Mayer, M.; Dano, K.; Blasi, F. (Univ. of Copenhagen (Denmark))

    1989-07-01

    Urokinase plasminogen activator (uPA) interacts with a surface receptor and with specific inhibitors, such as plasminogen activator inhibitor type 1 (PAI-1). These interactions are mediated by two functionally independent domains of the molecule: the catalytic domain (at the carboxyl terminus) and the growth factor domain (at the amino terminus). The authors have now investigated whether PAI-1 can bind and inhibit receptor-bound uPA. Binding of {sup 125}I-labeled ATF (amino-terminal fragment of uPA) to human U937 monocyte-like cells can be competed for by uPA-PAI-1 complexes, but not by PAI-1 alone. Preformed {sup 125}I-labeled uPA-PAI-1 complexes can bind to uPA receptor with the same binding specificity as uPA. PAI-1 also binds to, and inhibits the activity of, receptor-bound uPA in U937 cells, as shown in U937 cells by a caseinolytic plaque assay. Plasminogen activator activity of these cells is dependent on exogenous uPA, is competed for by receptor-binding diisopropyl fluorophosphate-treated uPA, and is inhibited by the addition of PAI-1. In conclusion, in U937 cells the binding to the receptor does not shield uPA from the action of PAI-1. The possibility that in adherent cells a different localization of PAI-1 and uPA leads to protection of uPA from PAI-1 is to be considered.

  16. Activation-Dependent Rapid Postsynaptic Clustering of Glycine Receptors in Mature Spinal Cord Neurons

    Science.gov (United States)

    Eto, Kei; Murakoshi, Hideji; Watanabe, Miho; Hirata, Hiromi; Moorhouse, Andrew J.; Ishibashi, Hitoshi

    2017-01-01

    Abstract Inhibitory synapses are established during development but continue to be generated and modulated in strength in the mature nervous system. In the spinal cord and brainstem, presynaptically released inhibitory neurotransmitter dominantly switches from GABA to glycine during normal development in vivo. While presynaptic mechanisms of the shift of inhibitory neurotransmission are well investigated, the contribution of postsynaptic neurotransmitter receptors to this shift is not fully elucidated. Synaptic clustering of glycine receptors (GlyRs) is regulated by activation-dependent depolarization in early development. However, GlyR activation induces hyperpolarization after the first postnatal week, and little is known whether and how presynaptically released glycine regulates postsynaptic receptors in a depolarization-independent manner in mature developmental stage. Here we developed spinal cord neuronal culture of rodents using chronic strychnine application to investigate whether initial activation of GlyRs in mature stage could change postsynaptic localization of GlyRs. Immunocytochemical analyses demonstrate that chronic blockade of GlyR activation until mature developmental stage resulted in smaller clusters of postsynaptic GlyRs that could be enlarged upon receptor activation for 1 h in the mature stage. Furthermore, live cell-imaging techniques show that GlyR activation decreases its lateral diffusion at synapses, and this phenomenon is dependent on PKC, but neither Ca2+ nor CaMKII activity. These results suggest that the GlyR activation can regulate receptor diffusion and cluster size at inhibitory synapses in mature stage, providing not only new insights into the postsynaptic mechanism of shifting inhibitory neurotransmission but also the inhibitory synaptic plasticity in mature nervous system. PMID:28197549

  17. An Angiotensin II type 1 receptor activation switch patch revealed through Evolutionary Trace analysis

    DEFF Research Database (Denmark)

    Bonde, Marie Mi; Yao, Rong; Ma, Jian-Nong

    2010-01-01

    to be completely resolved. Evolutionary Trace (ET) analysis is a computational method, which identifies clusters of functionally important residues by integrating information on evolutionary important residue variations with receptor structure. Combined with known mutational data, ET predicted a patch of residues......) displayed phenotypes associated with changed activation state, such as increased agonist affinity or basal activity, promiscuous activation, or constitutive internalization highlighting the importance of testing different signaling pathways. We conclude that this evolutionary important patch mediates...

  18. Excessive D1 Dopamine Receptor Activation in the Dorsal Striatum Promotes Autistic-Like Behaviors.

    Science.gov (United States)

    Lee, Yunjin; Kim, Hannah; Kim, Ji-Eun; Park, Jin-Young; Choi, Juli; Lee, Jung-Eun; Lee, Eun-Hwa; Han, Pyung-Lim

    2018-07-01

    The dopamine system has been characterized in motor function, goal-directed behaviors, and rewards. Recent studies recognize various dopamine system genes as being associated with autism spectrum disorder (ASD). However, how dopamine system dysfunction induces ASD pathophysiology remains unknown. In the present study, we demonstrated that mice with increased dopamine functions in the dorsal striatum via the suppression of dopamine transporter expression in substantia nigra neurons or the optogenetic stimulation of the nigro-striatal circuitry exhibited sociability deficits and repetitive behaviors relevant to ASD pathology in animal models, while these behavioral changes were blocked by a D1 receptor antagonist. Pharmacological activation of D1 dopamine receptors in normal mice or the genetic knockout (KO) of D2 dopamine receptors also produced typical autistic-like behaviors. Moreover, the siRNA-mediated inhibition of D2 dopamine receptors in the dorsal striatum was sufficient to replicate autistic-like phenotypes in D2 KO mice. Intervention of D1 dopamine receptor functions or the signaling pathways-related D1 receptors in D2 KO mice produced anti-autistic effects. Together, our results indicate that increased dopamine function in the dorsal striatum promotes autistic-like behaviors and that the dorsal striatum is the neural correlate of ASD core symptoms.

  19. Internalization mechanisms of the epidermal growth factor receptor after activation with different ligands.

    Directory of Open Access Journals (Sweden)

    Lasse Henriksen

    Full Text Available The epidermal growth factor receptor (EGFR regulates normal growth and differentiation, but dysregulation of the receptor or one of the EGFR ligands is involved in the pathogenesis of many cancers. There are eight ligands for EGFR, however most of the research into trafficking of the receptor after ligand activation focuses on the effect of epidermal growth factor (EGF and transforming growth factor-α (TGF-α. For a long time it was believed that clathrin-mediated endocytosis was the major pathway for internalization of the receptor, but recent work suggests that different pathways exist. Here we show that clathrin ablation completely inhibits internalization of EGF- and TGF-α-stimulated receptor, however the inhibition of receptor internalization in cells treated with heparin-binding EGF-like growth factor (HB-EGF or betacellulin (BTC was only partial. In contrast, clathrin knockdown fully inhibits EGFR degradation after all ligands tested. Furthermore, inhibition of dynamin function blocked EGFR internalization after stimulation with all ligands. Knocking out a number of clathrin-independent dynamin-dependent pathways of internalization had no effect on the ligand-induced endocytosis of the EGFR. We suggest that EGF and TGF-α lead to EGFR endocytosis mainly via the clathrin-mediated pathway. Furthermore, we suggest that HB-EGF and BTC also lead to EGFR endocytosis via a clathrin-mediated pathway, but can additionally use an unidentified internalization pathway or better recruit the small amount of clathrin remaining after clathrin knockdown.

  20. Internalization Mechanisms of the Epidermal Growth Factor Receptor after Activation with Different Ligands

    Science.gov (United States)

    Henriksen, Lasse; Grandal, Michael Vibo; Knudsen, Stine Louise Jeppe; van Deurs, Bo; Grøvdal, Lene Melsæther

    2013-01-01

    The epidermal growth factor receptor (EGFR) regulates normal growth and differentiation, but dysregulation of the receptor or one of the EGFR ligands is involved in the pathogenesis of many cancers. There are eight ligands for EGFR, however most of the research into trafficking of the receptor after ligand activation focuses on the effect of epidermal growth factor (EGF) and transforming growth factor-α (TGF-α). For a long time it was believed that clathrin-mediated endocytosis was the major pathway for internalization of the receptor, but recent work suggests that different pathways exist. Here we show that clathrin ablation completely inhibits internalization of EGF- and TGF-α-stimulated receptor, however the inhibition of receptor internalization in cells treated with heparin-binding EGF-like growth factor (HB-EGF) or betacellulin (BTC) was only partial. In contrast, clathrin knockdown fully inhibits EGFR degradation after all ligands tested. Furthermore, inhibition of dynamin function blocked EGFR internalization after stimulation with all ligands. Knocking out a number of clathrin-independent dynamin-dependent pathways of internalization had no effect on the ligand-induced endocytosis of the EGFR. We suggest that EGF and TGF-α lead to EGFR endocytosis mainly via the clathrin-mediated pathway. Furthermore, we suggest that HB-EGF and BTC also lead to EGFR endocytosis via a clathrin-mediated pathway, but can additionally use an unidentified internalization pathway or better recruit the small amount of clathrin remaining after clathrin knockdown. PMID:23472148

  1. Activation of GABAB receptors inhibits protein kinase B /Glycogen Synthase Kinase 3 signaling

    Directory of Open Access Journals (Sweden)

    Lu Frances Fangjia

    2012-11-01

    Full Text Available Abstract Accumulated evidence has suggested that potentiation of cortical GABAergic inhibitory neurotransmission may be a key mechanism in the treatment of schizophrenia. However, the downstream molecular mechanisms related to GABA potentiation remain unexplored. Recent studies have suggested that dopamine D2 receptor antagonists, which are used in the clinical treatment of schizophrenia, modulate protein kinase B (Akt/glycogen synthase kinase (GSK-3 signaling. Here we report that activation of GABAB receptors significantly inhibits Akt/GSK-3 signaling in a β-arrestin-dependent pathway. Agonist stimulation of GABAB receptors enhances the phosphorylation of Akt (Thr-308 and enhances the phosphorylation of GSK-3α (Ser-21/β (Ser-9 in both HEK-293T cells expressing GABAB receptors and rat hippocampal slices. Furthermore, knocking down the expression of β-arrestin2 using siRNA abolishes the GABAB receptor-mediated modulation of GSK-3 signaling. Our data may help to identify potentially novel targets through which GABAB receptor agents may exert therapeutic effects in the treatment of schizophrenia.

  2. Synthesis and nicotinic receptor activity of a hydroxylated tropane

    DEFF Research Database (Denmark)

    Bremner, John B; Godfrey, Colette A; Jensen, Anders A.

    2004-01-01

    (+/-)-3alpha-hydroxy homoepibatidine 4 has been synthesized from the alkaloid scopolamine 5 and its properties as a nicotinic agonist assessed. While still binding strongly, the compound showed reduced agonist potency for the alpha(4)beta(2) nAChR compared with the parent compound epibatidine 1....... Compound 4 also displayed generally similar binding and selectivity profiles at alpha(4)beta(2), alpha(2)beta(4), alpha(3)beta(4), and alpha(4)beta(4) nAChR subtypes to those for nicotine....

  3. Direct activation of Transient Receptor Potential Vanilloid 1(TRPV1 by Diacylglycerol (DAG

    Directory of Open Access Journals (Sweden)

    Oh Seog

    2008-10-01

    Full Text Available Abstract The capsaicin receptor, known as transient receptor potential channel vanilloid subtype 1 (TRPV1, is activated by a wide range of noxious stimulants and putative ligands such as capsaicin, heat, pH, anandamide, and phosphorylation by protein kinase C (PKC. However, the identity of endogenous activators for TRPV1 under physiological condition is still debated. Here, we report that diacylglycerol (DAG directly activates TRPV1 channel in a membrane-delimited manner in rat dorsal root ganglion (DRG neurons. 1-oleoyl-2-acetyl-sn-glycerol (OAG, a membrane-permeable DAG analog, elicited intracellular Ca2+ transients, cationic currents and cobalt uptake that were blocked by TRPV1-selective antagonists, but not by inhibitors of PKC and DAG lipase in rat DRG neurons or HEK 293 cells heterologously expressing TRPV1. OAG induced responses were about one fifth of capsaicin induced signals, suggesting that OAG displays partial agonism. We also found that endogenously produced DAG can activate rat TRPV1 channels. Mutagenesis of rat TRPV1 revealed that DAG-binding site is at Y511, the same site for capsaicin binding, and PtdIns(4,5P2binding site may not be critical for the activation of rat TRPV1 by DAG in heterologous system. We propose that DAG serves as an endogenous ligand for rat TRPV1, acting as an integrator of Gq/11-coupled receptors and receptor tyrosine kinases that are linked to phospholipase C.

  4. Role of tissue factor and protease-activated receptors in a mouse model of endotoxemia.

    Science.gov (United States)

    Pawlinski, Rafal; Pedersen, Brian; Schabbauer, Gernot; Tencati, Michael; Holscher, Todd; Boisvert, William; Andrade-Gordon, Patricia; Frank, Rolf Dario; Mackman, Nigel

    2004-02-15

    Sepsis is associated with a systemic activation of coagulation and an excessive inflammatory response. Anticoagulants have been shown to inhibit both coagulation and inflammation in sepsis. In this study, we used both genetic and pharmacologic approaches to analyze the role of tissue factor and protease-activated receptors in coagulation and inflammation in a mouse endotoxemia model. We used mice expressing low levels of the procoagulant molecule, tissue factor (TF), to analyze the effects of TF deficiency either in all tissues or selectively in hematopoietic cells. Low TF mice had reduced coagulation, inflammation, and mortality compared with control mice. Similarly, a deficiency of TF expression by hematopoietic cells reduced lipopolysaccharide (LPS)-induced coagulation, inflammation, and mortality. Inhibition of the down-stream coagulation protease, thrombin, reduced fibrin deposition and prolonged survival without affecting inflammation. Deficiency of either protease activated receptor-1 (PAR-1) or protease activated receptor-2 (PAR-2) alone did not affect inflammation or survival. However, a combination of thrombin inhibition and PAR-2 deficiency reduced inflammation and mortality. These data demonstrate that hematopoietic cells are the major pathologic site of TF expression during endotoxemia and suggest that multiple protease-activated receptors mediate crosstalk between coagulation and inflammation.

  5. Peroxisome Proliferator-Activated Receptor Ligands and Their Role in Chronic Myeloid Leukemia: Therapeutic Strategies.

    Science.gov (United States)

    Yousefi, Bahman; Samadi, Nasser; Baradaran, Behzad; Shafiei-Irannejad, Vahid; Zarghami, Nosratollah

    2016-07-01

    Imatinib therapy remains the gold standard for treatment of chronic myeloid leukemia; however, the acquired resistance to this therapeutic agent in patients has urged the scientists to devise modalities for overcoming this chemoresistance. For this purpose, initially therapeutic agents with higher tyrosine kinase activity were introduced, which had the potential for inhibiting even mutant forms of Bcr-Abl. Furthermore, coupling imatinib with peroxisome proliferator-activated receptor ligands also showed beneficial effects in chronic myeloid leukemia cell proliferation. These combination protocols inhibited cell growth and induced apoptosis as well as differentiation in chronic myeloid leukemia cell lines. In addition, peroxisome proliferator-activated receptors ligands increased imatinib uptake by upregulating the expression of human organic cation transporter 1. Taken together, peroxisome proliferator-activated receptors ligands are currently being considered as novel promising therapeutic candidates for chronic myeloid leukemia treatment, because they can synergistically enhance the efficacy of imatinib. In this article, we reviewed the potential of peroxisome proliferator-activated receptors ligands for use in chronic myeloid leukemia treatment. The mechanism of action of these therapeutics modalities are also presented in detail. © 2016 John Wiley & Sons A/S.

  6. [Study on influence between activated carbon property and immobilized biological activated carbon purification effect].

    Science.gov (United States)

    Wang, Guang-zhi; Li, Wei-guang; He, Wen-jie; Han, Hong-da; Ding, Chi; Ma, Xiao-na; Qu, Yan-ming

    2006-10-01

    By means of immobilizing five kinds of activated carbon, we studied the influence between the chief activated carbon property items and immobilized bioactivated carbon (IBAC) purification effect with the correlation analysis. The result shows that the activated carbon property items which the correlation coefficient is up 0.7 include molasses, abrasion number, hardness, tannin, uniform coefficient, mean particle diameter and effective particle diameter; the activated carbon property items which the correlation coefficient is up 0.5 include pH, iodine, butane and tetrachloride. In succession, the partial correlation analysis shows that activated carbon property items mostly influencing on IBAC purification effect include molasses, hardness, abrasion number, uniform coefficient, mean particle diameter and effective particle diameter. The causation of these property items bringing influence on IBAC purification is that the activated carbon holes distribution (representative activated carbon property item is molasses) provides inhabitable location and adjust food for the dominance bacteria; the mechanical resist-crash property of activated carbon (representative activated carbon property items: abrasion number and hardness) have influence on the stability of biofilm; and the particle diameter size and distribution of activated carbon (representative activated carbon property items: uniform coefficient, mean particle diameter and effective particle diameter) can directly affect the force of water in IBAC filter bed, which brings influence on the dominance bacteria immobilizing on activated carbon.

  7. Anti-tumor Activity of Toll-Like Receptor 7 Agonists

    Directory of Open Access Journals (Sweden)

    Huju Chi

    2017-05-01

    Full Text Available Toll-like receptors (TLRs are a class of pattern recognition receptors that play a bridging role in innate immunity and adaptive immunity. The activated TLRs not only induce inflammatory responses, but also elicit the development of antigen specific immunity. TLR7, a member of TLR family, is an intracellular receptor expressed on the membrane of endosomes. TLR7 can be triggered not only by ssRNA during viral infections, but also by immune modifiers that share a similar structure to nucleosides. Its powerful immune stimulatory action can be potentially used in the anti-tumor therapy. This article reviewed the anti-tumor activity and mechanism of TLR7 agonists that are frequently applied in preclinical and clinical investigations, and mainly focused on small synthetic molecules, including imiquimod, resiquimod, gardiquimod, and 852A, etc.

  8. Synthetic ligands of the elastin receptor induce elastogenesis in human dermal fibroblasts via activation of their IGF-1 receptors.

    Science.gov (United States)

    Qa'aty, Nour; Vincent, Matthew; Wang, Yanting; Wang, Andrew; Mitts, Thomas F; Hinek, Aleksander

    2015-12-01

    We have previously reported that a mixture of peptides obtained after chemical or enzymatic degradation of bovine elastin, induced new elastogenesis in human skin. Now, we investigated the elastogenic potential of synthetic peptides mimicking the elastin-derived, VGVAPG sequence, IGVAPG sequence that we found in the rice bran, and a similar peptide, VGVTAG that we identified in the IGF-1-binding protein-1 (IGFBP-1). We now demonstrate that treatment with each of these xGVxxG peptides (recognizable by the anti-elastin antibody), up-regulated the levels of elastin-encoding mRNA, tropoelastin protein, and the deposition of new elastic fibers in cultures of human dermal fibroblasts and in cultured explants of human skin. Importantly, we found that such induction of new elastogenesis may involve two parallel signaling pathways triggered after activation of IGF-1 receptor. In the first one, the xGVxxG peptides interact with the cell surface elastin receptor, thereby causing the downstream activation of the c-Src kinase and a consequent cross-activation of the adjacent IGF-1R, even in the absence of its principal ligand. In the second pathway their hydrophobic association with the N-terminal domain (VGVTAG) of the serum-derived IGFBP-1 induces conformational changes of this IGF-1 chaperone allowing for the release of its cargo and a consequent ligand-specific phosphorylation of IGF-1R. We present a novel, clinically relevant mechanism in which products of partial degradation of dermal elastin may stimulate production of new elastic fibers by dermal fibroblasts. Our findings particularly encourage the use of biologically safe synthetic xGVxxG peptides for regeneration of the injured or aged human skin. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  9. Protease-Activated Receptor 4 Variant p.Tyr157Cys Reduces Platelet Functional Responses and Alters Receptor Trafficking.

    Science.gov (United States)

    Norman, Jane E; Cunningham, Margaret R; Jones, Matthew L; Walker, Mary E; Westbury, Sarah K; Sessions, Richard B; Mundell, Stuart J; Mumford, Andrew D

    2016-05-01

    Protease-activated receptor 4 (PAR4) is a key regulator of platelet reactivity and is encoded by F2RL3, which has abundant rare missense variants. We aimed to provide proof of principle that rare F2LR3 variants potentially affect platelet reactivity and responsiveness to PAR1 antagonist drugs and to explore underlying molecular mechanisms. We identified 6 rare F2RL3 missense variants in 236 cardiac patients, of which the variant causing a tyrosine 157 to cysteine substitution (Y157C) was predicted computationally to have the greatest effect on PAR4 structure. Y157C platelets from 3 cases showed reduced responses to PAR4-activating peptide and to α-thrombin compared with controls, but no reduction in responses to PAR1-activating peptide. Pretreatment with the PAR1 antagonist vorapaxar caused lower residual α-thrombin responses in Y157C platelets than in controls, indicating greater platelet inhibition. HEK293 cells transfected with a PAR4 Y157C expression construct had reduced PAR4 functional responses, unchanged total PAR4 expression but reduced surface expression. PAR4 Y157C was partially retained in the endoplasmic reticulum and displayed an expression pattern consistent with defective N-glycosylation. Mutagenesis of Y322, which is the putative hydrogen bond partner of Y157, also reduced PAR4 surface expression in HEK293 cells. Reduced PAR4 responses associated with Y157C result from aberrant anterograde surface receptor trafficking, in part, because of disrupted intramolecular hydrogen bonding. Characterization of PAR4 Y157C establishes that rare F2RL3 variants have the potential to markedly alter platelet PAR4 reactivity particularly after exposure to therapeutic PAR1 antagonists. © 2016 American Heart Association, Inc.

  10. Nifedipine inhibits advanced glycation end products (AGEs) and their receptor (RAGE) interaction-mediated proximal tubular cell injury via peroxisome proliferator-activated receptor-gamma activation

    International Nuclear Information System (INIS)

    Matsui, Takanori; Yamagishi, Sho-ichi; Takeuchi, Masayoshi; Ueda, Seiji; Fukami, Kei; Okuda, Seiya

    2010-01-01

    Research highlights: → Nifedipine inhibited the AGE-induced up-regulation of RAGE mRNA levels in tubular cells, which was prevented by GW9662, an inhibitor of peroxisome proliferator-activated receptor-γ. → GW9662 treatment alone increased RAGE mRNA levels in tubular cells. → Nifedipine inhibited the AGE-induced reactive oxygen species generation, NF-κB activation and increases in intercellular adhesion molecule-1 and transforming growth factor-β gene expression in tubular cells, all of which were blocked by GW9662. -- Abstract: There is a growing body of evidence that advanced glycation end products (AGEs) and their receptor (RAGE) interaction evokes oxidative stress generation and subsequently elicits inflammatory and fibrogenic reactions, thereby contributing to the development and progression of diabetic nephropathy. We have previously found that nifedipine, a calcium-channel blocker (CCB), inhibits the AGE-induced mesangial cell damage in vitro. However, effects of nifedipine on proximal tubular cell injury remain unknown. We examined here whether and how nifedipine blocked the AGE-induced tubular cell damage. Nifedipine, but not amlodipine, a control CCB, inhibited the AGE-induced up-regulation of RAGE mRNA levels in tubular cells, which was prevented by the simultaneous treatment of GW9662, an inhibitor of peroxisome proliferator-activated receptor-γ (PPARγ). GW9662 treatment alone was found to increase RAGE mRNA levels in tubular cells. Further, nifedipine inhibited the AGE-induced reactive oxygen species generation, NF-κB activation and increases in intercellular adhesion molecule-1 and transforming growth factor-beta gene expression in tubular cells, all of which were blocked by GW9662. Our present study provides a unique beneficial aspect of nifedipine on diabetic nephropathy; it could work as an anti-oxidative and anti-inflammatory agent against AGEs in tubular cells by suppressing RAGE expression via PPARγ activation.

  11. Nifedipine inhibits advanced glycation end products (AGEs) and their receptor (RAGE) interaction-mediated proximal tubular cell injury via peroxisome proliferator-activated receptor-gamma activation

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, Takanori [Department of Pathophysiology and Therapeutics of Diabetic Vascular Complications, Kurume University School of Medicine, Kurume (Japan); Yamagishi, Sho-ichi, E-mail: shoichi@med.kurume-u.ac.jp [Department of Pathophysiology and Therapeutics of Diabetic Vascular Complications, Kurume University School of Medicine, Kurume (Japan); Takeuchi, Masayoshi [Department of Pathophysiological Science, Faculty of Pharmaceutical Science, Hokuriku University, Kanazawa (Japan); Ueda, Seiji; Fukami, Kei; Okuda, Seiya [Department of Medicine, Kurume University School of Medicine, Kurume (Japan)

    2010-07-23

    Research highlights: {yields} Nifedipine inhibited the AGE-induced up-regulation of RAGE mRNA levels in tubular cells, which was prevented by GW9662, an inhibitor of peroxisome proliferator-activated receptor-{gamma}. {yields} GW9662 treatment alone increased RAGE mRNA levels in tubular cells. {yields} Nifedipine inhibited the AGE-induced reactive oxygen species generation, NF-{kappa}B activation and increases in intercellular adhesion molecule-1 and transforming growth factor-{beta} gene expression in tubular cells, all of which were blocked by GW9662. -- Abstract: There is a growing body of evidence that advanced glycation end products (AGEs) and their receptor (RAGE) interaction evokes oxidative stress generation and subsequently elicits inflammatory and fibrogenic reactions, thereby contributing to the development and progression of diabetic nephropathy. We have previously found that nifedipine, a calcium-channel blocker (CCB), inhibits the AGE-induced mesangial cell damage in vitro. However, effects of nifedipine on proximal tubular cell injury remain unknown. We examined here whether and how nifedipine blocked the AGE-induced tubular cell damage. Nifedipine, but not amlodipine, a control CCB, inhibited the AGE-induced up-regulation of RAGE mRNA levels in tubular cells, which was prevented by the simultaneous treatment of GW9662, an inhibitor of peroxisome proliferator-activated receptor-{gamma} (PPAR{gamma}). GW9662 treatment alone was found to increase RAGE mRNA levels in tubular cells. Further, nifedipine inhibited the AGE-induced reactive oxygen species generation, NF-{kappa}B activation and increases in intercellular adhesion molecule-1 and transforming growth factor-beta gene expression in tubular cells, all of which were blocked by GW9662. Our present study provides a unique beneficial aspect of nifedipine on diabetic nephropathy; it could work as an anti-oxidative and anti-inflammatory agent against AGEs in tubular cells by suppressing RAGE expression

  12. Palliation of bone cancer pain by antagonists of platelet-activating factor receptors.

    Directory of Open Access Journals (Sweden)

    Katsuya Morita

    Full Text Available Bone cancer pain is the most severe among cancer pain and is often resistant to current analgesics. Thus, the development of novel analgesics effective at treating bone cancer pain are desired. Platelet-activating factor (PAF receptor antagonists were recently demonstrated to have effective pain relieving effects on neuropathic pain in several animal models. The present study examined the pain relieving effect of PAF receptor antagonists on bone cancer pain using the femur bone cancer (FBC model in mice. Animals were injected with osteolytic NCTC2472 cells into the tibia, and subsequently the effects of PAF receptor antagonists on pain behaviors were evaluated. Chemical structurally different type of antagonists, TCV-309, BN 50739 and WEB 2086 ameliorated the allodynia and improved pain behaviors such as guarding behavior and limb-use abnormalities in FBC model mice. The pain relieving effects of these antagonists were achieved with low doses and were long lasting. Blockade of spinal PAF receptors by intrathecal injection of TCV-309 and WEB 2086 or knockdown of the expression of spinal PAF receptor protein by intrathecal transfer of PAF receptor siRNA also produced a pain relieving effect. The amount of an inducible PAF synthesis enzyme, lysophosphatidylcholine acyltransferase 2 (LPCAT2 protein significantly increased in the spinal cord after transplantation of NCTC 2472 tumor cells into mouse tibia. The combination of morphine with PAF receptor antagonists develops marked enhancement of the analgesic effect against bone cancer pain without affecting morphine-induced constipation. Repeated administration of TCV-309 suppressed the appearance of pain behaviors and prolonged survival of FBC mice. The present results suggest that PAF receptor antagonists in combination with, or without, opioids may represent a new strategy for the treatment of persistent bone cancer pain and improve the quality of life of patients.

  13. Activation of temperature-sensitive TRPV1-like receptors in ARC POMC neurons reduces food intake.

    Directory of Open Access Journals (Sweden)

    Jae Hoon Jeong

    2018-04-01

    Full Text Available Proopiomelanocortin (POMC neurons in the arcuate nucleus of the hypothalamus (ARC respond to numerous hormonal and neural signals, resulting in changes in food intake. Here, we demonstrate that ARC POMC neurons express capsaicin-sensitive transient receptor potential vanilloid 1 receptor (TRPV1-like receptors. To show expression of TRPV1-like receptors in ARC POMC neurons, we use single-cell reverse transcription-polymerase chain reaction (RT-PCR, immunohistochemistry, electrophysiology, TRPV1 knock-out (KO, and TRPV1-Cre knock-in mice. A small elevation of temperature in the physiological range is enough to depolarize ARC POMC neurons. This depolarization is blocked by the TRPV1 receptor antagonist and by Trpv1 gene knockdown. Capsaicin-induced activation reduces food intake that is abolished by a melanocortin receptor antagonist. To selectively stimulate TRPV1-like receptor-expressing ARC POMC neurons in the ARC, we generate an adeno-associated virus serotype 5 (AAV5 carrying a Cre-dependent channelrhodopsin-2 (ChR2-enhanced yellow fluorescent protein (eYFP expression cassette under the control of the two neuronal POMC enhancers (nPEs. Optogenetic stimulation of TRPV1-like receptor-expressing POMC neurons decreases food intake. Hypothalamic temperature is rapidly elevated and reaches to approximately 39 °C during treadmill running. This elevation is associated with a reduction in food intake. Knockdown of the Trpv1 gene exclusively in ARC POMC neurons blocks the feeding inhibition produced by increased hypothalamic temperature. Taken together, our findings identify a melanocortinergic circuit that links acute elevations in hypothalamic temperature with acute reductions in food intake.

  14. Hyperfunctioning thyroid nodules in toxic multinodular goiter share activating thyrotropin receptor mutations with solitary toxic adenoma.

    Science.gov (United States)

    Tonacchera, M; Chiovato, L; Pinchera, A; Agretti, P; Fiore, E; Cetani, F; Rocchi, R; Viacava, P; Miccoli, P; Vitti, P

    1998-02-01

    Toxic multinodular goiter is a cause of nonautoimmune hyperthyroidism and is believed to differ in its nature and pathogenesis from toxic adenoma. Gain-of-function mutations of the TSH receptor gene have been identified as a cause of toxic adenoma. The pathogenesis at the molecular level of hyperfunctioning nodules in toxic multinodular goiter has yet not been reported. Six patients with a single hot nodule within a multinodular goiter and 11 patients with toxic thyroid adenoma were enrolled in our study. At histology five hyperfunctioning nodules in multinodular goiters showed the features of adenomas, and one was identified as a hyperplastic nodule. The entire exon 10 of the TSH receptor gene was directly sequenced after PCR amplification from genomic DNA obtained from surgical specimens. Functional studies of mutated receptors were performed in COS-7 cells. Five out of 6 (83%) hyperfunctioning nodules within toxic multinodular goiters harbored a TSH receptor mutation. A TSH receptor mutation was also evident in the hyperfunctioning nodule that at histology had the features of noncapsulated hyperplastic nodule. Among toxic adenomas, 8 out of 11 (72%) nodules harbored a TSH receptor mutation. All the mutations were heterozygotic and somatic. Nonfunctioning nodules, whether adenomas or hyperplastic nodules present in association with hyperfunctioning nodules in the same multinodular goiters, had no TSH receptor mutation. All the mutations identified had constitutive activity as assessed by cAMP production after expression in COS-7 cells. Hyperfunctioning thyroid nodules in multinodular goiters recognize the same pathogenetic event (TSH receptor mutation) as toxic adenoma. Other mechanisms are implicated in the growth of nonfunctioning thyroid nodules coexistent in the same gland.

  15. Receptor-G Protein Interaction Studied by Bioluminescence Resonance Energy Transfer: Lessons From Protease-Activated Receptor 1

    Directory of Open Access Journals (Sweden)

    Mohammed Akli eAYOUB

    2012-06-01

    Full Text Available Since its development, the bioluminescence resonance energy transfer (BRET approach has been extensively applied to study G protein-coupled receptors (GPCRs in real time and in live cells. One of the major aspects of GPCRs investigated in considerable details is their physical coupling to the heterotrimeric G proteins. As a result, new concepts have emerged, but few questions are still a matter of debate illustrating the complexity of GPCR-G protein interactions and coupling. Here, we summarized the recent advances on our understanding of GPCR-G protein coupling based on BRET approaches and supported by other FRET-based studies. We essentially focused on our recent studies in which we addressed the concept of preassembly versus the agonist-dependent interaction between the protease-activated receptor 1 (PAR1 and its cognate G proteins. We discussed the concept of agonist-induced conformational changes within the preassembled PAR1-G protein complexes as well as the critical question how the multiple coupling of PAR1 with two different G proteins, Gi1 and G12, but also -arrestin 1, can be regulated.

  16. Multiplicity of nuclear receptor activation by PFOA and PFOS in primary human and rodent hepatocytes

    International Nuclear Information System (INIS)

    Bjork, J.A.; Butenhoff, J.L.; Wallace, K.B.

    2011-01-01

    Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) are surface active fluorochemicals that, due to their exceptional stability to degradation, are persistent in the environment. Both PFOA and PFOS are eliminated slowly in humans, with geometric mean serum elimination half-lives estimated at 3.5 and 4.8 years, respectively. The biological activity of PFOA and PFOS in rodents is attributed primarily to transactivation of the nuclear receptor peroxisome proliferator activated receptor alpha (PPARA), which is an important regulator of lipid and carbohydrate metabolism. However, there are significant species-specific differences in the response to PFOA and PFOS exposure; non-rodent species, including humans, are refractory to several but not all of these effects. Many of the metabolic effects have been attributed to the activation of PPARA; however, recent studies using PPARα knockout mice demonstrate residual PPARA-independent effects, some of which may involve the activation of alternate nuclear receptors, including NR1I2 (PXR), NR1I3 (CAR), NR1H3 (LXRA), and NR1H4 (FXR). The objective of this investigation was to characterize the activation of multiple nuclear receptors and modulation of metabolic pathways associated with exposure to PFOA and PFOS, and to compare and contrast the effects between rat and human primary liver cells using quantitative reverse transcription PCR (RT-qPCR). Our results demonstrate that multiple nuclear receptors participate in the metabolic response to PFOA and PFOS exposure resulting in a substantial shift from carbohydrate metabolism to fatty acid oxidation and hepatic triglyceride accumulation in rat liver cells. This shift in intermediary metabolism was more pronounced for PFOA than PFOS. Furthermore, while there is some similarity in the activation of metabolic pathways between rat and humans, particularly in PPARA regulated responses; the changes in primary human cells were more subtle and possibly reflect an adaptive

  17. Structure-dependent binding and activation of perfluorinated compounds on human peroxisome proliferator-activated receptor γ

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lianying [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, 18 Shuangqing Road, Beijing 100085 (China); College of Life Science, Dezhou University, Dezhou 253023 (China); Ren, Xiao-Min; Wan, Bin [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, 18 Shuangqing Road, Beijing 100085 (China); Guo, Liang-Hong, E-mail: LHGuo@rcees.ac.cn [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, 18 Shuangqing Road, Beijing 100085 (China)

    2014-09-15

    Perfluorinated compounds (PFCs) have been shown to disrupt lipid metabolism and even induce cancer in rodents through activation of peroxisome proliferator-activated receptors (PPARs). Lines of evidence showed that PPARα was activated by PFCs. However, the information on the binding interactions between PPARγ and PFCs and subsequent alteration of PPARγ activity is still limited and sometimes inconsistent. In the present study, in vitro binding of 16 PFCs to human PPARγ ligand binding domain (hPPARγ-LBD) and their activity on the receptor in cells were investigated. The results showed that the binding affinity was strongly dependent on their carbon number and functional group. For the eleven perfluorinated carboxylic acids (PFCAs), the binding affinity increased with their carbon number from 4 to 11, and then decreased slightly. The binding affinity of the three perfluorinated sulfonic acids (PFSAs) was stronger than their PFCA counterparts. No binding was detected for the two fluorotelomer alcohols (FTOHs). Circular dichroim spectroscopy showed that PFC binding induced distinctive structural change of the receptor. In dual luciferase reporter assays using transiently transfected Hep G2 cells, PFCs acted as hPPARγ agonists, and their potency correlated with their binding affinity with hPPARγ-LBD. Molecular docking showed that PFCs with different chain length bind with the receptor in different geometry, which may contribute to their differences in binding affinity and transcriptional activity. - Highlights: • Binding affinity between PFCs and PPARγ was evaluated for the first time. • The binding strength was dependent on fluorinated carbon chain and functional group. • PFC binding induced distinctive structural change of the receptor. • PFCs could act as hPPARγ agonists in Hep G2 cells.

  18. Physicochemical and biological properties of novel amide-based steroidal inhibitors of NMDA receptors

    Czech Academy of Sciences Publication Activity Database

    Adla, Santosh Kumar; Slavíková, Barbora; Šmídková, Markéta; Tloušťová, Eva; Svoboda, Martin; Vyklický, Vojtěch; Krausová, Barbora; Hubálková, Pavla; Nekardová, Michaela; Holubová, Kristína; Valeš, Karel; Buděšínský, Miloš; Vyklický ml., Ladislav; Chodounská, Hana; Kudová, Eva

    2017-01-01

    Roč. 117, Jan (2017), s. 52-61 ISSN 0039-128X. [Conference on Isoprenoids /23./. Minsk, 04.09.2016-07.09.2016] R&D Projects: GA TA ČR(CZ) TE01020028; GA ČR(CZ) GAP303/12/1464; GA MŠk LO1302; GA MZd(CZ) NV15-29370A; GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:61388963 ; RVO:67985823 Keywords : neurosteroid * NMDA receptor * structure-activity relationship * amide * blood-brain-barrier permeability * Caco-2 assay Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry; Organic chemistry (FGU-C) Impact factor: 2.282, year: 2016

  19. Morphological and Photometric Properties of Active and Non-Active ...

    African Journals Online (AJOL)

    kagoyire

    2Mbarara University of Science and Technology, Fac. of Science, Physics Department, P.O.. Box 1410 ... evolutionary transition from the blue cloud to the red sequence galaxies. ... galaxies, we studied their properties in the green valley, and established the ..... The Morphological Content and Environmental Dependence of.

  20. Resveratrol, piceatannol and analogs inhibit activation of both wild-type and T877A mutant androgen receptor.

    Science.gov (United States)

    Lundqvist, Johan; Tringali, Corrado; Oskarsson, Agneta

    2017-11-01

    Prostate cancer growth and progression are mainly dependent on androgens and many current prostate cancer treatment options target the synthesis or function of androgens. We have previously reported that resveratrol and synthetic analogs of resveratrol with a higher bioavailability inhibit the synthesis of androgens in human adrenocortical H295R cells. Now we have studied the antiandrogenic properties of resveratrol, piceatannol and analogs in two different prostate cell lines; LNCaP and RWPE. LNCaP carry a T877A mutation in the androgen receptor while RWPE has a wild-type androgen receptor. We found that resveratrol, piceatannol and all studied analogs were able to inhibit a dihydrotestosterone-induced activation of the androgen receptor, showing that they act as antiandrogens. In LNCaP cells, all studied compounds were able to statistically significantly decrease the androgenic signaling in concentrations ≥1μM and the synthetic analogs trimethylresveratrol (RSVTM) and tetramethylpiceatannol (PICTM) were the most potent compounds. RWPE cells were not as responsive to the studied compounds as the LNCaP cells. A statistically significant decrease in the androgenic signaling was observed at concentrations ≤5μM for most compounds and RSVTM was found to be the most potent compound. Further, we studied the effects of resveratrol, piceatannol and analogs on the levels of prostate-specific antigen (PSA) in LNCaP cells and found that all studied compounds decreased the level of PSA and that the synthetic analogs diacetylresveratrol (RSVDA), triacetylresveratrol (RSVTA) and RSVTM were the most potent compounds, decreasing the PSA level by approx. 50% at concentrations ≥10μM. In a cell-free receptor binding assay we were unable to show binding of resveratrol or analogs to the ligand binding domain of the androgen receptor, indicating that the observed effects are mediated via other mechanisms than direct ligand competition. We conclude that the resveratrol

  1. Precursor Dependent Structural Properties and Antibacterial Activity ...

    Indian Academy of Sciences (India)

    71

    10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30 ... absorption spectroscopy, Scanning electron microscopy (SEM) and Zeta ... The antibacterial activity of the synthesized CuO were studied against human .... Sample d : Copper oxide synthesized with cupric sulphate as precursor ...... Chem.4 86.

  2. Medium chain fatty acids are selective peroxisome proliferator activated receptor (PPAR) γ activators and pan-PPAR partial agonists

    NARCIS (Netherlands)

    Liberato, Marcelo Vizoná; Nascimento, Alessandro S; Ayers, Steven D; Lin, Jean Z; Cvoro, Aleksandra; Silveira, Rodrigo L; Martínez, Leandro; Souza, Paulo C T; Saidemberg, Daniel; Deng, Tuo; Amato, Angela Angelica; Togashi, Marie; Hsueh, Willa A; Phillips, Kevin; Palma, Mário Sérgio; Neves, Francisco A R; Skaf, Munir S; Webb, Paul; Polikarpov, Igor

    2012-01-01

    Thiazolidinediones (TZDs) act through peroxisome proliferator activated receptor (PPAR) γ to increase insulin sensitivity in type 2 diabetes (T2DM), but deleterious effects of these ligands mean that selective modulators with improved clinical profiles are needed. We obtained a crystal structure of

  3. Constitutive Activity among Orphan Class-A G Protein Coupled Receptors.

    Directory of Open Access Journals (Sweden)

    Adam L Martin

    Full Text Available The purpose of this study was to evaluate the extent of constitutive activity among orphan class-A G protein coupled receptors within the cAMP signaling pathway. Constitutive signaling was revealed by changes in gene expression under control of the cAMP response element. Gene expression was measured in Chinese hamster ovary cells transiently co-transfected with plasmids containing a luciferase reporter and orphan receptor. Criteria adopted for defining constitutive activation were: 1 200% elevation over baseline reporter gene expression; 2 40% inhibition of baseline expression; and 3 40% inhibition of expression stimulated by 3 μM forskolin. Five patterns of activity were noted: 1 inhibition under both baseline and forskolin stimulated expression (GPR15, GPR17, GPR18, GPR20, GPR25, GPR27, GPR31, GPR32, GPR45, GPR57, GPR68, GPR83, GPR84, GPR132, GPR150, GPR176; 2 no effect on baseline expression, but inhibition of forskolin stimulated expression (GPR4, GPR26, GPR61, GPR62, GPR78, GPR101, GPR119; 3 elevation of baseline signaling coupled with inhibition of forskolin stimulated expression (GPR6, GPR12; 4 elevation of baseline signaling without inhibition of forskolin stimulated expression (GPR3, GPR21, GPR52, GPR65; and 5 no effect on expression (GPR1, GPR19, GPR22, GPR34, GPR35, GPR39, GPR63, GPR82, GPR85, GPR87. Constitutive activity was observed in 75% of the orphan class-A receptors examined (30 of 40. This constitutive signaling cannot be explained by simple overexpression of the receptor. Inhibition of cAMP mediated expression was far more common (65% than stimulation of expression (15%. Orphan receptors that were closely related based on amino acid homology tended to have similar effects on gene expression. These results suggest that identification of inverse agonists may be a fruitful approach for categorizing these orphan receptors and targeting them for pharmacological intervention.

  4. Constitutive Activity among Orphan Class-A G Protein Coupled Receptors.

    Science.gov (United States)

    Martin, Adam L; Steurer, Michael A; Aronstam, Robert S

    2015-01-01

    The purpose of this study was to evaluate the extent of constitutive activity among orphan class-A G protein coupled receptors within the cAMP signaling pathway. Constitutive signaling was revealed by changes in gene expression under control of the cAMP response element. Gene expression was measured in Chinese hamster ovary cells transiently co-transfected with plasmids containing a luciferase reporter and orphan receptor. Criteria adopted for defining constitutive activation were: 1) 200% elevation over baseline reporter gene expression; 2) 40% inhibition of baseline expression; and 3) 40% inhibition of expression stimulated by 3 μM forskolin. Five patterns of activity were noted: 1) inhibition under both baseline and forskolin stimulated expression (GPR15, GPR17, GPR18, GPR20, GPR25, GPR27, GPR31, GPR32, GPR45, GPR57, GPR68, GPR83, GPR84, GPR132, GPR150, GPR176); 2) no effect on baseline expression, but inhibition of forskolin stimulated expression (GPR4, GPR26, GPR61, GPR62, GPR78, GPR101, GPR119); 3) elevation of baseline signaling coupled with inhibition of forskolin stimulated expression (GPR6, GPR12); 4) elevation of baseline signaling without inhibition of forskolin stimulated expression (GPR3, GPR21, GPR52, GPR65); and 5) no effect on expression (GPR1, GPR19, GPR22, GPR34, GPR35, GPR39, GPR63, GPR82, GPR85, GPR87). Constitutive activity was observed in 75% of the orphan class-A receptors examined (30 of 40). This constitutive signaling cannot be explained by simple overexpression of the receptor. Inhibition of cAMP mediated expression was far more common (65%) than stimulation of expression (15%). Orphan receptors that were closely related based on amino acid homology tended to have similar effects on gene expression. These results suggest that identification of inverse agonists may be a fruitful approach for categorizing these orphan receptors and targeting them for pharmacological intervention.

  5. THERMOPHYSICAL PROPERTIES AND WATER ACTIVITY OF TRANSFERRED CHEESE (UF

    Directory of Open Access Journals (Sweden)

    Mohsen Dalvi Esfahan

    2015-06-01

    Full Text Available Few data are available on the thermophysical properties of cheese in the ripening process.The main objective of this work was to investigate the effects of brining and temperature on the thermophysical properties, i.e., thermal conductivity, specific heat, density and water activity of UF cheese and finally we measure surface heat transfer coefficient .Then we develop models for thermophysical properties based on physical and multiple regression concept .

  6. Palmitoylethanolamide exerts neuroprotective effects in mixed neuroglial cultures and organotypic hippocampal slices via peroxisome proliferator-activated receptor

    Directory of Open Access Journals (Sweden)

    Scuderi Caterina

    2012-03-01

    Full Text Available Abstract Background In addition to cytotoxic mechanisms directly impacting neurons, β-amyloid (Aβ-induced glial activation also promotes release of proinflammatory molecules that may self-perpetuate reactive gliosis and damage neighbouring neurons, thus amplifying neuropathological lesions occurring in Alzheimer's disease (AD. Palmitoylethanolamide (PEA has been studied extensively for its anti-inflammatory, analgesic, antiepileptic and neuroprotective effects. PEA is a lipid messenger isolated from mammalian and vegetable tissues that mimics several endocannabinoid-driven actions, even though it does not bind to cannabinoid receptors. Some of its pharmacological properties are considered to be dependent on the expression of peroxisome proliferator-activated receptors-α (PPARα. Findings In the present study, we evaluated the effect of PEA on astrocyte activation and neuronal loss in models of Aβ neurotoxicity. To this purpose, primary rat mixed neuroglial co-cultures and organotypic hippocampal slices were challenged with Aβ1-42 and treated with PEA in the presence or absence of MK886 or GW9662, which are selective PPARα and PPARγ antagonists, respectively. The results indicate that PEA is able to blunt Aβ-induced astrocyte activation and, subsequently, to improve neuronal survival through selective PPARα activation. The data from organotypic cultures confirm that PEA anti-inflammatory properties implicate PPARα mediation and reveal that the reduction of reactive gliosis subsequently induces a marked rebound neuroprotective effect on neurons. Conclusions In line with our previous observations, the results of this study show that PEA treatment results in decreased numbers of infiltrating astrocytes during Aβ challenge, resulting in significant neuroprotection. PEA could thus represent a promising pharmacological tool because it is able to reduce Aβ-evoked neuroinflammation and attenuate its neurodegenerative consequences.

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

    Energy Technology Data Exchange (ETDEWEB)

    Whelan, Jarrett T.; Wang, Lei; Chen, Jianming; Metts, Meagan E.; Nasser, Taj A.; McGoldrick, Liam J. [Department of Biochemistry and Molecular Biology, The Brody School of Medicine at East Carolina University, Greenville, NC 27834 (United States); Bridges, Lance C., E-mail: bridgesl@ecu.edu [Department of Biochemistry and Molecular Biology, The Brody School of Medicine at East Carolina University, Greenville, NC 27834 (United States); East Carolina Diabetes and Obesity Institute, The Brody School of Medicine at East Carolina University, Greenville, NC 27834 (United States)

    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 X 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 RAR-α receptor isotype. The current study provides novel molecular resolution as to which nuclear receptors transduce retinoid exposure into immune cell adhesion.

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

    International Nuclear Information System (INIS)

    Whelan, Jarrett T.; Wang, Lei; Chen, Jianming; Metts, Meagan E.; Nasser, Taj A.; McGoldrick, Liam J.; Bridges, Lance C.

    2014-01-01

    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 X 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) 2 D 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 RAR-α receptor isotype. The current study provides novel molecular resolution as to which nuclear receptors transduce retinoid exposure into immune cell adhesion

  9. Activation of muscarinic acetylcholine receptors elicits pigment granule dispersion in retinal pigment epithelium isolated from bluegill.

    Science.gov (United States)

    González, Alfredo; Crittenden, Elizabeth L; García, Dana M

    2004-07-13

    In fish, melanin pigment granules in the retinal pigment epithelium disperse into apical projections as part of the suite of responses the eye makes to bright light conditions. This pigment granule dispersion serves to reduce photobleaching and occurs in response to neurochemicals secreted by the retina. Previous work has shown that acetylcholine may be involved in inducing light-adaptive pigment dispersion. Acetylcholine receptors are of two main types, nicotinic and muscarinic. Muscarinic receptors are in the G-protein coupled receptor superfamily, and five different muscarinic receptors have been molecularly cloned in human. These receptors are coupled to adenylyl cyclase, calcium mobilization and ion channel activation. To determine the receptor pathway involved in eliciting pigment granule migration, we isolated retinal pigment epithelium from bluegill and subjected it to a battery of cholinergic agents. The general cholinergic agonist carbachol induces pigment granule dispersion in isolated retinal pigment epithelium. Carbachol-induced pigment granule dispersion is blocked by the muscarinic antagonist atropine, by the M1 antagonist pirenzepine, and by the M3 antagonist 4-DAMP. Pigment granule dispersion was also induced by the M1 agonist 4-[N-(4-chlorophenyl) carbamoyloxy]-4-pent-2-ammonium iodide. In contrast the M2 antagonist AF-DX 116 and the M4 antagonist tropicamide failed to block carbachol-induced dispersion, and the M2 agonist arecaidine but-2-ynyl ester tosylate failed to elicit dispersion. Our results suggest that carbachol-mediated pigment granule dispersion occurs through the activation of Modd muscarinic receptors, which in other systems couple to phosphoinositide hydrolysis and elevation of intracellular calcium. This conclusion must be corroborated by molecular studies, but suggests Ca2+-dependent pathways may be involved in light-adaptive pigment dispersion.

  10. Activation of muscarinic acetylcholine receptors elicits pigment granule dispersion in retinal pigment epithelium isolated from bluegill

    Directory of Open Access Journals (Sweden)

    Crittenden Elizabeth L

    2004-07-01

    Full Text Available Abstract Background In fish, melanin pigment granules in the retinal pigment epithelium disperse into apical projections as part of the suite of responses the eye makes to bright light conditions. This pigment granule dispersion serves to reduce photobleaching and occurs in response to neurochemicals secreted by the retina. Previous work has shown that acetylcholine may be involved in inducing light-adaptive pigment dispersion. Acetylcholine receptors are of two main types, nicotinic and muscarinic. Muscarinic receptors are in the G-protein coupled receptor superfamily, and five different muscarinic receptors have been molecularly cloned in human. These receptors are coupled to adenylyl cyclase, calcium mobilization and ion channel activation. To determine the receptor pathway involved in eliciting pigment granule migration, we isolated retinal pigment epithelium from bluegill and subjected it to a battery of cholinergic agents. Results The general cholinergic agonist carbachol induces pigment granule dispersion in isolated retinal pigment epithelium. Carbachol-induced pigment granule dispersion is blocked by the muscarinic antagonist atropine, by the M1 antagonist pirenzepine, and by the M3 antagonist 4-DAMP. Pigment granule dispersion was also induced by the M1 agonist 4-[N-(4-chlorophenyl carbamoyloxy]-4-pent-2-ammonium iodide. In contrast the M2 antagonist AF-DX 116 and the M4 antagonist tropicamide failed to block carbachol-induced dispersion, and the M2 agonist arecaidine but-2-ynyl ester tosylate failed to elicit dispersion. Conclusions Our results suggest that carbachol-mediated pigment granule dispersion occurs through the activation of Modd muscarinic receptors, which in other systems couple to phosphoinositide hydrolysis and elevation of intracellular calcium. This conclusion must be corroborated by molecular studies, but suggests Ca2+-dependent pathways may be involved in light-adaptive pigment dispersion.

  11. Activation of neurokinin-1 receptors during ozone inhalation contributes to epithelial injury and repair.

    Science.gov (United States)

    Oslund, Karen L; Hyde, Dallas M; Putney, Leialoha F; Alfaro, Mario F; Walby, William F; Tyler, Nancy K; Schelegle, Edward S

    2008-09-01

    We investigated the importance of neurokinin (NK)-1 receptors in epithelial injury and repair and neutrophil function. Conscious Wistar rats were exposed to 1 ppm ozone or filtered air for 8 hours, followed by an 8-hour postexposure period. Before exposure, we administered either the NK-1 receptor antagonist, SR140333, or saline as a control. Ethidium homodimer was instilled into lungs as a marker of necrotic airway epithelial cells. After fixation, whole mounts of airway dissected lung lobes were immunostained for 5-bromo-2'-deoxyuridine, a marker of epithelial proliferation. Both ethidium homodimer and 5-bromo-2'-deoxyuridine-positive epithelial cells were quantified in specific airway generations. Rats treated with the NK-1 receptor antagonist had significantly reduced epithelial injury and epithelial proliferation compared with control rats. Sections of terminal bronchioles showed no significant difference in the number of neutrophils in airways between groups. In addition, staining ozone-exposed lung sections for active caspase 3 showed no apoptotic cells, but ethidium-positive cells colocalized with the orphan nuclear receptor, Nur77, a marker of nonapoptotic, programmed cell death mediated by the NK-1 receptor. An immortalized human airway epithelial cell line, human bronchial epithelial-1, showed no significant difference in the number of oxidant stress-positive cells during exposure to hydrogen peroxide and a range of SR140333 doses, demonstrating no antioxidant effect of the receptor antagonist. We conclude that activation of the NK-1 receptor during acute ozone inhalation contributes to epithelial injury and subsequent epithelial proliferation, a critical component of repair, but does not influence neutrophil emigration into airways.

  12. Peroxisome proliferator-activated receptor gamma coactivator-1 alpha acts as a tumor suppressor in hepatocellular carcinoma.

    Science.gov (United States)

    Liu, Rui; Zhang, Haiyang; Zhang, Yan; Li, Shuang; Wang, Xinyi; Wang, Xia; Wang, Cheng; Liu, Bin; Zen, Ke; Zhang, Chen-Yu; Zhang, Chunni; Ba, Yi

    2017-04-01

    Peroxisome proliferator-activated receptor gamma coactivator-1 alpha plays a crucial role in regulating the biosynthesis of mitochondria, which is closely linked to the energy metabolism in various tumors. This study investigated the regulatory role of peroxisome proliferator-activated receptor gamma coactivator-1 alpha in the pathogenesis of hepatocellular carcinoma. In this study, the changes of peroxisome proliferator-activated receptor gamma coactivator-1 alpha messenger RNA levels between normal human liver and hepatocellular carcinoma tissue were examined by quantitative reverse transcription polymerase chain reaction. Knockdown of peroxisome proliferator-activated receptor gamma coactivator-1 alpha was conducted by RNA interference in the human liver cell line L02, while overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha was conducted by adenovirus encoding peroxisome proliferator-activated receptor gamma coactivator-1 alpha complementary DNA in the human hepatocarcinoma cell line HepG2. Cellular morphological changes were observed via optical and electron microscopy. Cellular apoptosis was determined by Hoechst 33258 staining. In addition, the expression levels of 21,400 genes in tissues and cells were detected by microarray. It was shown that peroxisome proliferator-activated receptor gamma coactivator-1 alpha expression was significantly downregulated in hepatocellular carcinoma compared with normal liver tissues. After knockdown of peroxisome proliferator-activated receptor gamma coactivator-1 alpha expression in L02 cells, cells reverted to immature and dedifferentiated morphology exhibiting cancerous tendency. Apoptosis occurred in the HepG2 cells after transfection by adenovirus encoding peroxisome proliferator-activated receptor gamma coactivator-1 alpha. Microarray analysis showed consistent results. The results suggest that peroxisome proliferator-activated receptor gamma coactivator-1 alpha acts as a tumor

  13. Effects of histamine H1 receptor signaling on glucocorticoid receptor activity. Role of canonical and non-canonical pathways

    NARCIS (Netherlands)

    Zappia, C.D.; Granja-Galeano, G.; Fernández, N.; Shayo, C.; Davio, C.; Fitzsimons, C.P.; Monczor, F.

    2015-01-01

    Histamine H1 receptor (H1R) antagonists and glucocorticoid receptor (GR) agonists are used to treat inflammatory conditions such as allergic rhinitis, atopic dermatitis and asthma. Consistent with the high morbidity levels of such inflammatory conditions, these receptors are the targets of a vast

  14. Screening of phytochemicals against protease activated receptor 1 (PAR1), a promising target for cancer.

    Science.gov (United States)

    Kakarala, Kavita Kumari; Jamil, Kaiser

    2015-02-01

    Drug resistance and drug-associated toxicity are the primary causes for withdrawal of many drugs, although patient recovery is satisfactory in many instances. Interestingly, the use of phytochemicals in the treatment of cancer as an alternative to synthetic drugs comes with a host of advantages; minimum side effects, good human absorption and low toxicity to normal cells. Protease activated receptor 1 (PAR1) has been established as a promising target in many diseases including various cancers. Strong evidences suggest its role in metastasis also. There are no natural compounds known to inhibit its activity, so we aimed to identify phytochemicals with antagonist activity against PAR1. We screened phytochemicals from Naturally Occurring Plant-based Anticancer Compound-Activity-Target database (NPACT, http://crdd.osdd.net/raghava/npact/ ) against PAR1 using virtual screening workflow of Schrödinger software. It analyzes pharmaceutically relevant properties using Qikprop and calculates binding energy using Glide at three accuracy levels (high-throughput virtual screening, standard precision and extra precision). Our study led to the identification of phytochemicals, which showed interaction with at least one experimentally determined active site residue of PAR1, showed no violations to Lipinski's rule of five along with predicted high human absorption. Furthermore, structural interaction fingerprint analysis indicated that the residues H255, D256, E260, S344, V257, L258, L262, Y337 and S344 may play an important role in the hydrogen bond interactions of the phytochemicals screened. Of these residues, H255 and L258 residues were experimentally proved to be important for antagonist binding. The residues Y183, L237, L258, L262, F271, L332, L333, Y337, L340, A349, Y350, A352, and Y353 showed maximum hydrophobic interactions with the phytochemicals screened. The results of this work suggest that phytochemicals Reissantins D, 24,25-dihydro-27-desoxywithaferin A, Isoguaiacin

  15. Insulin resistance in uremia: Insulin receptor kinase activity in liver and muscle from chronic uremic rats

    International Nuclear Information System (INIS)

    Cecchin, F.; Ittoop, O.; Sinha, M.K.; Caro, J.F.

    1988-01-01

    The authors have studied the structure and function of the partially purified insulin receptors from liver and skeletal muscle in a rat model of severe chronic uremia. 125 I-insulin binding was higher in the liver from uremic rats when compared with ad libitum- and pair-fed controls. Furthermore, the ability of insulin to stimulate the autophosphorylation of the β-subunit and insulin receptor kinase activity using Glu 80 , Tyr 20 as exogenous phosphoacceptor was increased in the liver of the uremic animals. The structural characteristics of the receptors, as determined by electrophoretic mobilities of affinity labeled α-subunit and the phosphorylated β-subunit, were normal in uremia. 125 I-insulin binding and insulin receptor kinase activity were similar in the skeletal muscle from uremic and pair- and ad libitum-fed animals. Thus the data are supportive of the hypothesis that in liver and muscle of chronic uremic rats, insulin resistance is due to a defect(s) distal to the insulin receptor kinase

  16. High affinity soluble ILT2 receptor: a potent inhibitor of CD8(+) T cell activation.

    Science.gov (United States)

    Moysey, Ruth K; Li, Yi; Paston, Samantha J; Baston, Emma E; Sami, Malkit S; Cameron, Brian J; Gavarret, Jessie; Todorov, Penio; Vuidepot, Annelise; Dunn, Steven M; Pumphrey, Nicholas J; Adams, Katherine J; Yuan, Fang; Dennis, Rebecca E; Sutton, Deborah H; Johnson, Andy D; Brewer, Joanna E; Ashfield, Rebecca; Lissin, Nikolai M; Jakobsen, Bent K

    2010-12-01

    Using directed mutagenesis and phage display on a soluble fragment of the human immunoglobulin super-family receptor ILT2 (synonyms: LIR1, MIR7, CD85j), we have selected a range of mutants with binding affinities enhanced by up to 168,000-fold towards the conserved region of major histocompatibility complex (MHC) class I molecules. Produced in a dimeric form, either by chemical cross-linking with bivalent polyethylene glycol (PEG) derivatives or as a genetic fusion with human IgG Fc-fragment, the mutants exhibited a further increase in ligand-binding strength due to the avidity effect, with resident half-times (t(1/2)) on the surface of MHC I-positive cells of many hours. The novel compounds antagonized the interaction of CD8 co-receptor with MHC I in vitro without affecting the peptide-specific binding of T-cell receptors (TCRs). In both cytokine-release assays and cell-killing experiments the engineered receptors inhibited the activation of CD8(+) cytotoxic T lymphocytes (CTLs) in the presence of their target cells, with subnanomolar potency and in a dose-dependent manner. As a selective inhibitor of CD8(+) CTL responses, the engineered high affinity ILT2 receptor presents a new tool for studying the activation mechanism of different subsets of CTLs and could have potential for the development of novel autoimmunity therapies.

  17. Enveloped viruses disable innate immune responses in dendritic cells by direct activation of TAM receptors.

    Science.gov (United States)

    Bhattacharyya, Suchita; Zagórska, Anna; Lew, Erin D; Shrestha, Bimmi; Rothlin, Carla V; Naughton, John; Diamond, Michael S; Lemke, Greg; Young, John A T

    2013-08-14

    Upon activation by the ligands Gas6 and Protein S, Tyro3/Axl/Mer (TAM) receptor tyrosine kinases promote phagocytic clearance of apoptotic cells and downregulate immune responses initiated by Toll-like receptors and type I interferons (IFNs). Many enveloped viruses display the phospholipid phosphatidylserine on their membranes, through which they bind Gas6 and Protein S and engage TAM receptors. We find that ligand-coated viruses activate TAM receptors on dendritic cells (DCs), dampen type I IFN signaling, and thereby evade host immunity and promote infection. Upon virus challenge, TAM-deficient DCs display type I IFN responses that are elevated in comparison to wild-type cells. As a consequence, TAM-deficient DCs are relatively resistant to infection by flaviviruses and pseudotyped retroviruses, but infection can be restored with neutralizing type I IFN antibodies. Correspondingly, a TAM kinase inhibitor antagonizes the infection of wild-type DCs. Thus, TAM receptors are engaged by viruses in order to attenuate type I IFN signaling and represent potential therapeutic targets. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Dreamlike effects of LSD on waking imagery in humans depend on serotonin 2A receptor activation.

    Science.gov (United States)

    Kraehenmann, Rainer; Pokorny, Dan; Vollenweider, Leonie; Preller, Katrin H; Pokorny, Thomas; Seifritz, Erich; Vollenweider, Franz X

    2017-07-01

    Accumulating evidence indicates that the mixed serotonin and dopamine receptor agonist lysergic acid diethylamide (LSD) induces an altered state of consciousness that resembles dreaming. This study aimed to test the hypotheses that LSD produces dreamlike waking imagery and that this imagery depends on 5-HT2A receptor activation and is related to subjective drug effects. Twenty-five healthy subjects performed an audiorecorded guided mental imagery task 7 h after drug administration during three drug conditions: placebo, LSD (100 mcg orally) and LSD together with the 5-HT2A receptor antagonist ketanserin (40 mg orally). Cognitive bizarreness of guided mental imagery reports was quantified as a standardised formal measure of dream mentation. State of consciousness was evaluated using the Altered State of Consciousness (5D-ASC) questionnaire. LSD, compared with placebo, significantly increased cognitive bizarreness (p < 0.001). The LSD-induced increase in cognitive bizarreness was positively correlated with the LSD-induced loss of self-boundaries and cognitive control (p < 0.05). Both LSD-induced increases in cognitive bizarreness and changes in state of consciousness were fully blocked by ketanserin. LSD produced mental imagery similar to dreaming, primarily via activation of the 5-HT2A receptor and in relation to loss of self-boundaries and cognitive control. Future psychopharmacological studies should assess the differential contribution of the D2/D1 and 5-HT1A receptors to cognitive bizarreness.

  19. The role of chemokines and chemokine receptors in eosinophil activation during inflammatory allergic reactions

    Directory of Open Access Journals (Sweden)

    Oliveira S.H.P.

    2003-01-01

    Full Text Available Chemokines are important chemotactic cytokines that play a fundamental role in the trafficking of leukocytes to sites of inflammation. They are also potent cell-activating factors, inducing cytokine and histamine release and free radical production, a fact that makes them particularly important in the pathogenesis of allergic inflammation. The action of chemokines is regulated at the level of agonist production and processing as well as at the level of receptor expression and coupling. Therefore, an analysis of the ligands must necessarily consider receptors. Eosinophils are target cells involved in the allergic inflammatory response since they are able to release a wide variety of mediators including CC and CXC chemokines and express their receptors. These mediators could damage the airway epithelial cells and might be important to stimulate other cells inducing an amplification of the allergic response. This review focuses on recently emerging data pertaining to the importance of chemokines and chemokine receptors in promoting eosinophil activation and migration during the allergic inflammatory process. The analysis of the function of eosinophils and their chemokine receptors during allergic inflammation might be a good approach to understanding the determinants of asthma severity and to developing novel therapies.

  20. Microwave absorbing properties of activated carbon fibre polymer ...

    Indian Academy of Sciences (India)

    cations in the field of radar and electromagnetic compatibility. (Singh et al ... fibres have irregular-shaped cross sections (shown in fig- ure 1) ... Microwave absorbing properties of activated carbon fibre polymer composites. 77. 2. 4. 6. 8. 10. 12.

  1. Structural rearrangement of the intracellular domains during AMPA receptor activation

    DEFF Research Database (Denmark)

    Zachariassen, Linda Grønborg; Katchan, Ljudmila; Jensen, Anna Guldvang

    2016-01-01

    -clamp fluorometry of the double- and single-insert constructs showed that both the intracellular C-terminal domain (CTD) and the loop region between the M1 and M2 helices move during activation and the CTD is detached from the membrane. Our time-resolved measurements revealed unexpectedly complex fluorescence...

  2. Receptor-heteromer mediated regulation of endocannabinoid signaling in activated microglia. Role of CB1 and CB2 receptors and relevance for Alzheimer's disease and levodopa-induced dyskinesia.

    Science.gov (United States)

    Navarro, Gemma; Borroto-Escuela, Dasiel; Angelats, Edgar; Etayo, Íñigo; Reyes-Resina, Irene; Pulido-Salgado, Marta; Rodríguez-Pérez, Ana I; Canela, Enric I; Saura, Josep; Lanciego, José Luis; Labandeira-García, José Luis; Saura, Carlos A; Fuxe, Kjell; Franco, Rafael

    2018-01-01

    Endocannabinoids are important regulators of neurotransmission and, acting on activated microglia, they are postulated as neuroprotective agents. Endocannabinoid action is mediated by CB 1 and CB 2 receptors, which may form heteromeric complexes (CB 1 -CB 2 Hets) with unknown function in microglia. We aimed at establishing the expression and signaling properties of cannabinoid receptors in resting and LPS/IFN-γ-activated microglia. In activated microglia mRNA transcripts increased (2 fold for CB 1 and circa 20 fold for CB 2 ), whereas receptor levels were similar for CB 1 and markedly upregulated for CB 2 ; CB 1 -CB 2 Hets were also upregulated. Unlike in resting cells, CB 2 receptors became robustly coupled to G i in activated cells, in which CB 1 -CB 2 Hets mediated a potentiation effect. Hence, resting cells were refractory while activated cells were highly responsive to cannabinoids. Interestingly, similar results were obtained in cultures treated with ß-amyloid (Aß 1-42 ). Microglial activation markers were detected in the striatum of a Parkinson's disease (PD) model and, remarkably, in primary microglia cultures from the hippocampus of mutant β-amyloid precursor protein (APP Sw,Ind ) mice, a transgenic Alzheimer's disease (AD) model. Also of note was the similar cannabinoid receptor signaling found in primary cultures of microglia from APP Sw,Ind and in cells from control animals activated using LPS plus IFN-γ. Expression of CB 1 -CB 2 Hets was increased in the striatum from rats rendered dyskinetic by chronic levodopa treatment. In summary, our results showed sensitivity of activated microglial cells to cannabinoids, increased CB 1 -CB 2 Het expression in activated microglia and in microglia from the hippocampus of an AD model, and a correlation between levodopa-induced dyskinesia and striatal microglial activation in a PD model. Cannabinoid receptors and the CB 1 -CB 2 heteroreceptor complex in activated microglia have potential as targets in the

  3. Protease-activated receptor (PAR)-2 is required for PAR-1 signalling in pulmonary fibrosis

    NARCIS (Netherlands)

    Lin, Cong; von der Thüsen, Jan; Daalhuisen, Joost; ten Brink, Marieke; Crestani, Bruno; van der Poll, Tom; Borensztajn, Keren; Spek, C. Arnold

    2015-01-01

    Idiopathic pulmonary fibrosis is the most devastating diffuse fibrosing lung disease of unknown aetiology. Compelling evidence suggests that both protease-activated receptor (PAR)-1 and PAR-2 participate in the development of pulmonary fibrosis. Previous studies have shown that bleomycin-induced

  4. Pharmacological targeting of protease-activated receptor 2 affords protection from bleomycin-induced pulmonary fibrosis

    NARCIS (Netherlands)

    C. Lin (Cong); J. von der Thusen (Jan); J. Daalhuisen (Joost); M. Ten Brink (Marieke); B. Crestani (Bruno); T. van der Poll (Tom); K. Borensztajn (Keren); C. Arnold Spek (C.)

    2015-01-01

    textabstractIdiopathic pulmonary fibrosis is the most devastating diffuse fibrosing lung disease that remains refractory to therapy. Despite increasing evidence that protease-activated receptor 2 (PAR-2) contributes to fibrosis, its importance in pulmonary fibrosis is under debate. We addressed

  5. Pharmacological Targeting of Protease-Activated Receptor 2 Affords Protection from Bleomycin-Induced Pulmonary Fibrosis

    NARCIS (Netherlands)

    Lin, Cong; von der Thüsen, Jan; Daalhuisen, Joost; ten Brink, Marieke; Crestani, Bruno; van der Poll, Tom; Borensztajn, Keren; Spek, C. Arnold

    2015-01-01

    Idiopathic pulmonary fibrosis is the most devastating diffuse fibrosing lung disease that remains refractory to therapy. Despite increasing evidence that protease-activated receptor 2 (PAR-2) contributes to fibrosis, its importance in pulmonary fibrosis is under debate. We addressed whether PAR-2

  6. Distinct neural pathways mediate alpha7 nicotinic acetylcholine receptor-dependent activation of the forebrain

    DEFF Research Database (Denmark)

    Thomsen, Morten S; Hay-Schmidt, Anders; Hansen, Henrik H

    2010-01-01

    alpha(7) nicotinic acetylcholine receptor (nAChR) agonists are candidates for the treatment of cognitive deficits in schizophrenia. Selective alpha(7) nAChR agonists, such as SSR180711, activate neurons in the medial prefrontal cortex (mPFC) and nucleus accumbens shell (ACCshell) in rats, regions...

  7. Activation of the Ah receptor by extracts of dietary herbal supplements, vegetables and fruits

    NARCIS (Netherlands)

    Jeuken, A.; Keser, B.J.G.; Khan, E.; Brouwer, A.; Koeman, J.; Denison, M.S.

    2003-01-01

    The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that can be activated by a structurally diverse range of synthetic and natural chemicals, and it mediates the toxic and biological effects of environmental contaminants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

  8. Activation of the Ah receptor by extracts of dietary herbal supplements, vegetables, and fruits

    NARCIS (Netherlands)

    Jeuken, A.; Keser, B.J.G.; Khan, E.; Brouwer, A.; Koeman, J.H.; Denison, M.S.

    2003-01-01

    The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that can be activated by a structurally diverse range of synthetic and natural chemicals, and it mediates the toxic and biological effects of environmental contaminants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

  9. RECEPTOR POTENTIAL AND LIGHT-INDUCED MITOCHONDRIAL ACTIVATION IN BLOWFLY PHOTORECEPTOR MUTANTS

    NARCIS (Netherlands)

    MOJET, MH; TINBERGEN, J; STAVENGA, DG

    1991-01-01

    1. Simultaneous measurements of the receptor potential and the light-induced mitochondrial activation were performed in white-eyed blowflies Calliphora vicina, mutant chalky, and Lucilia cuprina, mutants w(F) and w'nss. The intensity dependence and the temporal dynamics were investigated. 2. The

  10. Soluble receptors for tumor necrosis factor as markers of disease activity in visceral leishmaniasis

    NARCIS (Netherlands)

    Zijlstra, E. E.; van der Poll, T.; Mevissen, M.

    1995-01-01

    Serum concentrations of soluble receptors for tumor necrosis factor (sTNFRs) were measured before and after antimony therapy in 25 Sudanese patients with active visceral leishmaniasis (VL). Both sTNFR types I and II were significantly elevated in patients with VL compared with healthy controls from

  11. The orphan G protein-coupled receptor GPR139 is activated by the peptides

    DEFF Research Database (Denmark)

    Jensen, Anne Cathrine Nøhr; Shehata, Mohamed A; Hauser, Alexander S

    2017-01-01

    GPR139 is an orphan G protein-coupled receptor that is expressed primarily in the brain. Not much is known regarding the function of GPR139. Recently we have shown that GPR139 is activated by the amino acids l-tryptophan and l-phenylalanine (EC50 values of 220 μM and 320 μM, respectively), as well...

  12. Genomic organization of the mouse peroxisome proliferator-activated receptor beta/delta gene

    DEFF Research Database (Denmark)

    Larsen, Leif K; Amri, Ez-Zoubir; Mandrup, Susanne

    2002-01-01

    Peroxisome proliferator-activated receptor (PPAR) beta/delta is ubiquitously expressed, but the level of expression differs markedly between different cell types. In order to determine the molecular mechanisms governing PPARbeta/delta gene expression, we have isolated and characterized the mouse...

  13. A new metabotropic glutamate receptor agonist with in vivo anti-allodynic activity

    DEFF Research Database (Denmark)

    Stanley, Nathan J; Hutchinson, Mark R; Kvist, Trine

    2010-01-01

    -substituted carboxycyclopropylglycines, utilizing novel synthetic chemistry. The reaction between substituted 1,2-dioxines and an aminophosphonate furnished the cyclopropane core in a single step with all required stereochemistry of pendant groups. In vitro binding assays at metabotropic glutamate receptors revealed selective activity...

  14. Epigenetic Basis for the Regulation of Estrogen Receptor Alpha Activity in Breast Cancer Cells

    Science.gov (United States)

    2009-04-01

    Contreras, J.I., Prescott , M.S., Dagenais, S.L., Wu, R., Yee, J., Orringer, M.B., Misek, D.E., Hanash, S.M., et al. (2002). The hepatocyte nuclear... Microbiology . All Rights Reserved. Coactivator Function Defines the Active Estrogen Receptor Alpha Cistrome† Mathieu Lupien,1‡ Jérôme Eeckhoute,1

  15. Deletion of protease-activated receptor 2 prolongs survival of scrapie-inoculated mice

    Czech Academy of Sciences Publication Activity Database

    Matěj, R.; Olejár, Tomáš; Janoušková, O.; Holada, K.

    2012-01-01

    Roč. 93, č. 9 (2012), s. 2057-2061 ISSN 0022-1317 Institutional support: RVO:67985823 Keywords : protease-activated receptor (PAR2) * scrapie * neurodegenerative disorders Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology Impact factor: 3.127, year: 2012

  16. Metal ion site engineering indicates a global toggle switch model for seven-transmembrane receptor activation

    DEFF Research Database (Denmark)

    Elling, Christian E; Frimurer, Thomas M; Gerlach, Lars-Ole

    2006-01-01

    for monoamine binding in TM-III, was used as the starting point to engineer activating metal ion sites between the extracellular segments of the beta2-adrenergic receptor. Cu(II) and Zn(II) alone and in complex with aromatic chelators acted as potent (EC50 decreased to 0.5 microm) and efficacious agonists...

  17. Soluble urokinase plasminogen activator receptor as a prognostic marker in men participating in prostate cancer screening

    DEFF Research Database (Denmark)

    Kjellman, A; Akre, O; Gustafsson, O

    2011-01-01

    BACKGROUND: The urokinase plasminogen activator (uPA) system is involved in tissue remodelling processes and is up-regulated in many types of malignancies. We investigated whether serum levels of different forms of soluble uPA receptor (suPAR) are associated with survival and in particular with p...

  18. Toll-like receptor activation reveals developmental reorganization and unmasks responder subsets of microglia

    NARCIS (Netherlands)

    Scheffel, Joerg; Regen, Tommy; Van Rossum, Denise; Seifert, Stefanie; Ribes, Sandra; Nau, Roland; Parsa, Roham; Harris, Robert A.; Boddeke, Hendrikus W. G. M.; Chuang, Han-Ning; Pukrop, Tobias; Wessels, Johannes T.; Juergens, Tanja; Merkler, Doron; Brueck, Wolfgang; Schnaars, Mareike; Simons, Mikael; Kettenmann, Helmut; Hanisch, Uwe-Karsten

    2012-01-01

    The sentinel and immune functions of microglia require rapid and appropriate reactions to infection and damage. Their Toll-like receptors (TLRs) sense both as threats. However, whether activated microglia mount uniform responses or whether subsets conduct selective tasks is unknown. We demonstrate

  19. Liver X receptor activation restores memory in aged AD mice without reducing amyloid

    NARCIS (Netherlands)

    Vanmierlo, Tim; Rutten, Kris; Dederen, Jos; Bloks, Vincent W.; van Vark-van der Zee, Leonie C.; Kuipers, Folkert; Kiliaan, Amanda; Blokland, Arjan; Sijbrands, Eric J. G.; Steinbusch, Harry; Prickaerts, Jos; Luetjohann, Dieter; Mulder, Monique

    Alterations in cerebral cholesterol metabolism are thought to play a role in the progression of Alzheimer's disease (AD). Liver X receptors (LXRs) are key regulators of cholesterol metabolism. The synthetic LXR activator, T0901317 has been reported to improve memory functions in animal models for AD

  20. Soluble urokinase-type plasminogen activator receptor forms in plasma as markers of atherosclerotic plaque vulnerability

    DEFF Research Database (Denmark)

    Olson, Fredrik J; Thurison, Tine; Ryndel, Mikael

    2009-01-01

    OBJECTIVES:: To test if circulating forms of the soluble urokinase-type plasminogen activator receptor (suPAR) are potential biomarkers of plaque vulnerability. DESIGN AND METHODS:: Plasma concentrations of suPAR(I-III), suPAR(II-III) and uPAR(I) were measured by time-resolved fluorescence immuno...

  1. The human receptor for urokinase plasminogen activator. NH2-terminal amino acid sequence and glycosylation variants

    DEFF Research Database (Denmark)

    Behrendt, N; Rønne, E; Ploug, M

    1990-01-01

    The receptor for human urokinase-type plasminogen activator (u-PA) was purified from phorbol 12-myristate 13-acetate-stimulated U937 cells by temperature-induced phase separation of detergent extracts, followed by affinity chromatography with immobilized diisopropyl fluorophosphate-treated u...

  2. Importance of the extracellular loops in G protein-coupled receptors for ligand recognition and receptor activation.

    Science.gov (United States)

    Peeters, M C; van Westen, G J P; Li, Q; IJzerman, A P

    2011-01-01

    G protein-coupled receptors (GPCRs) are the major drug target of medicines on the market today. Therefore, much research is and has been devoted to the elucidation of the function and three-dimensional structure of this large family of membrane proteins, which includes multiple conserved transmembrane domains connected by intra- and extracellular loops. In the last few years, the less conserved extracellular loops have garnered increasing interest, particularly after the publication of several GPCR crystal structures that clearly show the extracellular loops to be involved in ligand binding. This review will summarize the recent progress made in the clarification of the ligand binding and activation mechanism of class-A GPCRs and the role of extracellular loops in this process. Copyright © 2010 Elsevier Ltd. All rights reserved.

  3. Assessment of human pregnane X receptor involvement in pesticide-mediated activation of CYP3A4 gene.

    Science.gov (United States)

    Matsubara, Tsutomu; Noracharttiyapot, Wachiraporn; Toriyabe, Takayoshi; Yoshinari, Kouichi; Nagata, Kiyoshi; Yamazoe, Yasushi

    2007-05-01

    Assessment of foreign chemical inducibility on CYP3A4 is necessary to optimize drug therapies. The properties of chemicals such as pesticides, however, are not well investigated. In the present study, properties of various pesticides on human CYP3A4 induction have been tested using HepG2-derived cells stably expressing the CYP3A4 promoter/enhancer (3-1-10 cells) and the human pregnane X receptor (hPXR)-small interfering RNA (siRNA) system. Among the examined pesticides, 13 pesticides were observed to activate the CYP3A4 gene. Surprisingly, pyributicarb was found to increase the CYP3A4 reporter activity at 0.1 to 1 microM more strongly than typical CYP3A4 inducer rifampicin. Expression of hPXR-siRNA clearly diminished the pyributicarb-stimulated CYP3A4 reporter activity in 3-1-10 cells and decreased the endogenous CYP3A4 mRNA levels in HepG2 cells. Pyributicarb caused enhancement of CYP3A4-derived reporter activity in mouse livers introduced with hPXR by adenovirus. These results indicate pyributicarb as a potent activator of CYP3A4 gene, suggesting the existence of pesticides leading to CYP3A4 induction in our environment.

  4. Biological activity of cloned mammary tumor virus DNA fragments that bind purified glucocorticoid receptor protein in vitro

    International Nuclear Information System (INIS)

    Yamamoto, K.R.; Payvar, F.; Firestone, G.L.; Maler, B.A.; Wrange, O.; Carlstedt-Duke, J.; Gustafsson, J.A.; Chandler, V.L.; Karolinska Institutet, Stockholm, Sweden)

    1983-01-01

    To test whether high-affinity receptor:DNA interactions can be correlated with receptor effects on promoter function in vivo, we have mapped in greater detail the receptor-binding regions on murine mammary tumor virus DNA, using both nitrocellulose-filter binding and electron microscopy. Recombinant plasmids bearing these receptor-binding domains have been transfected into cultured cells, and the expression of the plasmid sequences has been monitored for hormonal regulation. The results are considered in terms of a speculative proposal that the glucocorticoid receptor may effect changes in promoter activity via specific alteration of chromatin and/or DNA structure. 37 references, 6 figures, 2 tables

  5. Neuroligin-1 induces neurite outgrowth through interaction with neurexin-1ß and activation of fibroblast growth factor receptor-1

    DEFF Research Database (Denmark)

    Gjørlund, Michelle D; Nielsen, Janne; Pankratova, Stanislava

    2012-01-01

    Neurexin-1 (NRXN1) and neuroligin-1 (NLGN1) are synaptic cell adhesion molecules that connect pre- and postsynaptic neurons at synapses and mediate signaling across the synapse, which modulates synaptic activity and determines the properties of neuronal networks. Defects in the genes encoding NLGN1...... have been linked to cognitive diseases such as autism. The roles of both NRXN1 and NLGN1 during synaptogenesis have been studied extensively, but little is known about the role of these molecules in neuritogenesis, which eventually results in neuronal circuitry formation. The present study investigated...... the neuritogenic effect of NLGN1 in cultures of hippocampal neurons. Our results show that NLGN1, both in soluble and membrane-bound forms, induces neurite outgrowth that depends on the interaction with NRXN1ß and on activation of fibroblast growth factor receptor-1. In addition, we demonstrate that a synthetic...

  6. Cloning and expression of the receptor for human urokinase plasminogen activator, a central molecule in cell surface, plasmin dependent proteolysis

    DEFF Research Database (Denmark)

    Roldan, A.L.; Cubellis, M.V.; Masucci, M.T.

    1990-01-01

    , and therefore the capacity of cells to migrate and invade neighboring tissues. We have isolated a 1.4 kb cDNA clone coding for the entire human uPAR. An oligonucleotide synthesized on the basis of the N-terminal sequence of the purified protein was used to screen a cDNA library made from SV40 transformed human......, a size very close to that of the cloned cDNA. Expression of the uPAR cDNA in mouse cells confirms that the clone is complete and expresses a functional uPA binding protein, located on the cell surface and with properties similar to the human uPAR. Caseinolytic plaque assay, immunofluorescence analysis......The surface receptor for urokinase plasminogen activator (uPAR) has been recognized in recent years as a key molecule in regulating plasminogen mediated extracellular proteolysis. Surface plasminogen activation controls the connections between cells, basement membrane and extracellular matrix...

  7. Multiple autophosphorylation sites of the epidermal growth factor receptor are essential for receptor kinase activity and internalization. Contrasting significance of tyrosine 992 in the native and truncated receptors

    DEFF Research Database (Denmark)

    Sorkin, A; Helin, K; Waters, C M

    1992-01-01

    The role of epidermal growth factor (EGF) receptor autophosphorylation sites in the regulation of receptor functions has been studied using cells transfected with mutant EGF receptors. Simultaneous point mutation of 4 tyrosines (Y1068, Y1086, Y1148, Y1173) to phenylalanine, as well as removal of ...

  8. Insect Repellents: Modulators of Mosquito Odorant Receptor Activity

    Science.gov (United States)

    2010-08-01

    Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Plant Sciences Institute, Agricultural Research Service, United States Department...origin. 2-U is a naturally occurring compound produced by the glandular trichomes of wild tomato plants as part of a plant defense mechanism against...antennal OSNs responding to carboxylic acids and monoterpenes [23]. In our study, we investigate the action of 4 insect repellents on the activities of

  9. Activation of dopamine receptors in the nucleus accumbens promotes sucrose-reinforced cued approach behavior

    Directory of Open Access Journals (Sweden)

    Saleem M. Nicola

    2016-07-01

    Full Text Available Dopamine receptor activation in the nucleus accumbens (NAc promotes vigorous environmentally-cued food-seeking in hungry rats. Rats fed ad libitum, however, respond to fewer food-predictive cues, particularly when the value of food reward is low. Here, we investigated whether this difference could be due to differences in the degree of dopamine receptor activation in the NAc. First, we observed that although rats given ad libitum access to chow in their home cages approached a food receptacle in response to reward-predictive cues, the number of such approaches declined as animals accumulated food rewards. Intriguingly, cued approach to food occurred in clusters, with several cued responses followed by successive non-responses. This pattern suggested that behavior was dictated by transitions between two states, responsive and non-responsive. Injection of D1 or D2 dopamine receptor agonists into the NAc dose-dependently increased cue responding by promoting transitions to the responsive state and by preventing transitions to the non-responsive state. In contrast, antagonists of either D1 or D2 receptors promoted long bouts of non-responding by inducing transitions to the non-responsive state and by preventing transitions to the responsive state. Moreover, locomotor behavior during the inter-trial interval was correlated with the responsive state, and was also increased by dopamine receptor agonists. These results suggest that activation of NAc dopamine receptors plays an important role in regulating the probability of approach to food under conditions of normative satiety.

  10. Insulin receptor substrates 1 and 2 but not Shc can activate the insulin receptor independent of insulin and induce proliferation in CHO-IR cells

    International Nuclear Information System (INIS)

    Niessen, Markus; Jaschinski, Frank; Item, Flurin; McNamara, Morgan P.; Spinas, Giatgen A.; Trueb, Thomas

    2007-01-01

    Ligand-activated insulin receptor (IR) attracts and phosphorylates various substrates such as insulin receptor substrates 1-4 (IRS) and Shc. To investigate how binding affinity for substrate affects signalling we generated chimeric receptors with the β-chain of the insulin receptor containing NPXY motives with different affinities for receptor substrates. We found that the extent of receptor tyrosine phosphorylation positively correlates with binding affinity towards IRS1/2 but not towards Shc. Moreover, overexpression of IRS1 or IRS2 but not of Shc increased IR tyrosine phosphorylation in a dose-dependent manner, also independent of insulin. Molecular truncations of IRS1 revealed that neither the isolated PH and PTB domains nor the C-terminus with the tyrosine phosphorylation sites alone are sufficient for substrate-dependent receptor activation. Overexpression of IRS1 and IRS2 impaired insulin-induced internalization of the IR in a dose-dependent manner suggesting that IRS proteins prevent endosome-associated receptor dephosphorylation/inactivation. IRS1 and IRS2 could therefore target the activated IR to different cellular compartments. Overexpression of IRS1 and IRS2 inhibited insulin-stimulated activation of the MAP kinases Erk1/2 while it increased/induced activation of Akt/PKB. Finally, overexpression of IRS1 and IRS2 but not of Shc induced DNA synthesis in starved CHO-IR cells independent of exogenous growth factors. Our results demonstrate that variations in cellular IRS1 and IRS2 concentration affect insulin signalling both upstream and downstream and that IRS proteins could play instructive rather than just permissive roles in signal transmission

  11. mTORC2 promotes type I insulin-like growth factor receptor and insulin receptor activation through the tyrosine kinase activity of mTOR.

    Science.gov (United States)

    Yin, Yancun; Hua, Hui; Li, Minjing; Liu, Shu; Kong, Qingbin; Shao, Ting; Wang, Jiao; Luo, Yuanming; Wang, Qian; Luo, Ting; Jiang, Yangfu

    2016-01-01

    Mammalian target of rapamycin (mTOR) is a core component of raptor-mTOR (mTORC1) and rictor-mTOR (mTORC2) complexes that control diverse cellular processes. Both mTORC1 and mTORC2 regulate several elements downstream of type I insulin-like growth factor receptor (IGF-IR) and insulin receptor (InsR). However, it is unknown whether and how mTOR regulates IGF-IR and InsR themselves. Here we show that mTOR possesses unexpected tyrosine kinase activity and activates IGF-IR/InsR. Rapamycin induces the tyrosine phosphorylation and activation of IGF-IR/InsR, which is largely dependent on