Involvement of ERK in NMDA receptor-independent cortical neurotoxicity of hydrogen sulfide

International Nuclear Information System (INIS)

Kurokawa, Yuko; Sekiguchi, Fumiko; Kubo, Satoko; Yamasaki, Yoshiko; Matsuda, Sachi; Okamoto, Yukari; Sekimoto, Teruki; Fukatsu, Anna; Nishikawa, Hiroyuki; Kume, Toshiaki; Fukushima, Nobuyuki; Akaike, Akinori; Kawabata, Atsufumi

2011-01-01

Highlights: ► Hydrogen sulfide causes NMDA receptor-independent neurotoxicity in mouse fetal cortical neurons. ► Activation of ERK mediates the toxicity of hydrogen sulfide. ► Apoptotic mechanisms are involved in the hydrogen-induced cell death. -- Abstract: Hydrogen sulfide (H 2 S), a gasotransmitter, exerts both neurotoxicity and neuroprotection, and targets multiple molecules including NMDA receptors, T-type calcium channels and NO synthase (NOS) that might affect neuronal viability. Here, we determined and characterized effects of NaHS, an H 2 S donor, on cell viability in the primary cultures of mouse fetal cortical neurons. NaHS caused neuronal death, as assessed by LDH release and trypan blue staining, but did not significantly reduce the glutamate toxicity. The neurotoxicity of NaHS was resistant to inhibitors of NMDA receptors, T-type calcium channels and NOS, and was blocked by inhibitors of MEK, but not JNK, p38 MAP kinase, PKC and Src. NaHS caused prompt phosphorylation of ERK and upregulation of Bad, followed by translocation of Bax to mitochondria and release of mitochondrial cytochrome c, leading to the nuclear condensation/fragmentation. These effects of NaHS were suppressed by the MEK inhibitor. Our data suggest that the NMDA receptor-independent neurotoxicity of H 2 S involves activation of the MEK/ERK pathway and some apoptotic mechanisms.

Postoperative ileus involves interleukin-1 receptor signaling in enteric glia.

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Stoffels, Burkhard; Hupa, Kristof Johannes; Snoek, Susanne A; van Bree, Sjoerd; Stein, Kathy; Schwandt, Timo; Vilz, Tim O; Lysson, Mariola; Veer, Cornelis Van't; Kummer, Markus P; Hornung, Veit; Kalff, Joerg C; de Jonge, Wouter J; Wehner, Sven

2014-01-01

Postoperative ileus (POI) is a common consequence of abdominal surgery that increases the risk of postoperative complications and morbidity. We investigated the cellular mechanisms and immune responses involved in the pathogenesis of POI. We studied a mouse model of POI in which intestinal manipulation leads to inflammation of the muscularis externa and disrupts motility. We used C57BL/6 (control) mice as well as mice deficient in Toll-like receptors (TLRs) and cytokine signaling components (TLR-2(-/-), TLR-4(-/-), TLR-2/4(-/-), MyD88(-/-), MyD88/TLR adaptor molecule 1(-/-), interleukin-1 receptor [IL-1R1](-/-), and interleukin (IL)-18(-/-) mice). Bone marrow transplantation experiments were performed to determine which cytokine receptors and cell types are involved in the pathogenesis of POI. Development of POI did not require TLRs 2, 4, or 9 or MyD88/TLR adaptor molecule 2 but did require MyD88, indicating a role for IL-1R1. IL-1R1(-/-) mice did not develop POI; however, mice deficient in IL-18, which also signals via MyD88, developed POI. Mice given injections of an IL-1 receptor antagonist (anakinra) or antibodies to deplete IL-1α and IL-1β before intestinal manipulation were protected from POI. Induction of POI activated the inflammasome in muscularis externa tissues of C57BL6 mice, and IL-1α and IL-1β were released in ex vivo organ bath cultures. In bone marrow transplantation experiments, the development of POI required activation of IL-1 receptor in nonhematopoietic cells. IL-1R1 was expressed by enteric glial cells in the myenteric plexus layer, and cultured primary enteric glia cells expressed IL-6 and the chemokine monocyte chemotactic protein 1 in response to IL-1β stimulation. Immunohistochemical analysis of human small bowel tissue samples confirmed expression of IL-1R1 in the ganglia of the myenteric plexus. IL-1 signaling, via IL-1R1 and MyD88, is required for development of POI after intestinal manipulation in mice. Agents that interfere with

Glucocorticoid receptor modulators.

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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.

Electroacupuncture Inhibition of Hyperalgesia in Rats with Adjuvant Arthritis: Involvement of Cannabinoid Receptor 1 and Dopamine Receptor Subtypes in Striatum

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Yin Shou

2013-01-01

Full Text Available Electroacupuncture (EA has been regarded as an alternative treatment for inflammatory pain for several decades. However, the molecular mechanisms underlying the antinociceptive effect of EA have not been thoroughly clarified. Previous studies have shown that cannabinoid CB1 receptors are related to pain relief. Accumulating evidence has shown that the CB1 and dopamine systems sometimes interact and may operate synergistically in rat striatum. To our knowledge, dopamine D1/D2 receptors are involved in EA analgesia. In this study, we found that repeated EA at Zusanli (ST36 and Kunlun (BL60 acupoints resulted in marked improvements in thermal hyperalgesia. Both western blot assays and FQ-PCR analysis results showed that the levels of CB1 expression in the repeated-EA group were much higher than those in any other group (P=0.001. The CB1-selective antagonist AM251 inhibited the effects of repeated EA by attenuating the increases in CB1 expression. The two kinds of dopamine receptors imparted different actions on the EA-induced CB1 upregulation in AA rat model. These results suggested that the strong activation of the CB1 receptor after repeated EA resulted in the concomitant phenomenon of the upregulation of D1 and D2 levels of gene expression.

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...

Involvement of dopamine D2 receptors in addictive-like behaviour for acetaldehyde.

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Brancato, Anna; Plescia, Fulvio; Marino, Rosa Anna Maria; Maniaci, Giuseppe; Navarra, Michele; Cannizzaro, Carla

2014-01-01

Acetaldehyde, the first metabolite of ethanol, is active in the central nervous system, where it exerts motivational properties. Acetaldehyde is able to induce drinking behaviour in operant-conflict paradigms that resemble the core features of the addictive phenotype: drug-intake acquisition and maintenance, drug-seeking, relapse and drug use despite negative consequences. Since acetaldehyde directly stimulates dopamine neuronal firing in the mesolimbic system, the aim of this study was the investigation of dopamine D2-receptors' role in the onset of the operant drinking behaviour for acetaldehyde in different functional stages, by the administration of two different D2-receptor agonists, quinpirole and ropinirole. Our results show that acetaldehyde was able to induce and maintain a drug-taking behaviour, displaying an escalation during training, and a reinstatement behaviour after 1-week forced abstinence. Acetaldehyde operant drinking behaviour involved D2-receptor signalling: in particular, quinpirole administration at 0.03 mg/kg, induced a significant decrease in the number of lever presses both in extinction and in relapse. Ropinirole, administered at 0.03 mg/kg during extinction, did not produce any modification but, when administered during abstinence, induced a strong decrease in acetaldehyde intake in the following relapse session. Taken together, our data suggest that acetaldehyde exerts its own motivational properties, involving the dopaminergic transmission: indeed, activation of pre-synaptic D2-receptors by quinpirole, during extinction and relapse, negatively affects operant behaviour for acetaldehyde, likely decreasing acetaldehyde-induced dopamine release. The activation of post-synaptic D2-receptors by ropinirole, during abstinence, decreases the motivation to the consecutive reinstatement of acetaldehyde drinking behaviour, likely counteracting the reduction in the dopaminergic tone typical of withdrawal. These data further strengthen the evidence

Involvement of dopamine D2 receptors in addictive-like behaviour for acetaldehyde.

Directory of Open Access Journals (Sweden)

Anna Brancato

Full Text Available Acetaldehyde, the first metabolite of ethanol, is active in the central nervous system, where it exerts motivational properties. Acetaldehyde is able to induce drinking behaviour in operant-conflict paradigms that resemble the core features of the addictive phenotype: drug-intake acquisition and maintenance, drug-seeking, relapse and drug use despite negative consequences. Since acetaldehyde directly stimulates dopamine neuronal firing in the mesolimbic system, the aim of this study was the investigation of dopamine D2-receptors' role in the onset of the operant drinking behaviour for acetaldehyde in different functional stages, by the administration of two different D2-receptor agonists, quinpirole and ropinirole. Our results show that acetaldehyde was able to induce and maintain a drug-taking behaviour, displaying an escalation during training, and a reinstatement behaviour after 1-week forced abstinence. Acetaldehyde operant drinking behaviour involved D2-receptor signalling: in particular, quinpirole administration at 0.03 mg/kg, induced a significant decrease in the number of lever presses both in extinction and in relapse. Ropinirole, administered at 0.03 mg/kg during extinction, did not produce any modification but, when administered during abstinence, induced a strong decrease in acetaldehyde intake in the following relapse session. Taken together, our data suggest that acetaldehyde exerts its own motivational properties, involving the dopaminergic transmission: indeed, activation of pre-synaptic D2-receptors by quinpirole, during extinction and relapse, negatively affects operant behaviour for acetaldehyde, likely decreasing acetaldehyde-induced dopamine release. The activation of post-synaptic D2-receptors by ropinirole, during abstinence, decreases the motivation to the consecutive reinstatement of acetaldehyde drinking behaviour, likely counteracting the reduction in the dopaminergic tone typical of withdrawal. These data further

Evidence for the involvement of MC4 receptors in the central mechanisms of opioid antinociception

NARCIS (Netherlands)

Starowicz, Katarzyna

2005-01-01

The data described in this thesis extend general knowledge of the involvement of the MC4 receptor in mechanisms of analgesia. The following aspects outlined below constitute novel information. Firstly, the MC4R localization in the DRG is demonstrated. The MC4 receptor was assumed to exist

Receptors involved in the modulation of guinea pig urinary bladder motility by prostaglandin D2

Science.gov (United States)

Guan, Na N; Svennersten, Karl; de Verdier, Petra J; Wiklund, N Peter; Gustafsson, Lars E

2015-01-01

Background and Purpose We have described a urothelium-dependent release of PGD2-like activity which had inhibitory effects on the motility of guinea pig urinary bladder. Here, we have pharmacologically characterized the receptors involved and localized the sites of PGD2 formation and of its receptors. Experimental Approach In the presence of selective DP and TP receptor antagonists alone or combined, PGD2 was applied to urothelium-denuded diclofenac-treated urinary bladder strips mounted in organ baths. Antibodies against PGD2 synthase and DP1 receptors were used with Western blots and for histochemistry. Key Results PGD2 inhibited nerve stimulation -induced contractions in strips of guinea pig urinary bladder with estimated pIC50 of 7.55 ± 0.15 (n = 13), an effect blocked by the DP1 receptor antagonist BW-A868C. After blockade of DP1 receptors, PGD2 enhanced the contractions, an effect abolished by the TP receptor antagonist SQ-29548. Histochemistry revealed strong immunoreactivity for PGD synthase in the urothelium/suburothelium with strongest reaction in the suburothelium. Immunoreactive DP1 receptors were found in the smooth muscle of the bladder wall with a dominant localization to smooth muscle membranes. Conclusions and Implications In guinea pig urinary bladder, the main effect of PGD2 is an inhibitory action via DP1 receptors localized to the smooth muscle, but an excitatory effect via TP receptors can also be evoked. The urothelium with its suburothelium might signal to the smooth muscle which is rich in PGD2 receptors of the DP1 type. The results are important for our understanding of regulation of bladder motility. PMID:25917171

The hedgehog receptor patched is involved in cholesterol transport.

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Michel Bidet

Full Text Available Sonic hedgehog (Shh signaling plays a crucial role in growth and patterning during embryonic development, and also in stem cell maintenance and tissue regeneration in adults. Aberrant Shh pathway activation is involved in the development of many tumors, and one of the most affected Shh signaling steps found in these tumors is the regulation of the signaling receptor Smoothened by the Shh receptor Patched. In the present work, we investigated Patched activity and the mechanism by which Patched inhibits Smoothened.Using the well-known Shh-responding cell line of mouse fibroblasts NIH 3T3, we first observed that enhancement of the intracellular cholesterol concentration induces Smoothened enrichment in the plasma membrane, which is a crucial step for the signaling activation. We found that binding of Shh protein to its receptor Patched, which involves Patched internalization, increases the intracellular concentration of cholesterol and decreases the efflux of a fluorescent cholesterol derivative (BODIPY-cholesterol from these cells. Treatment of fibroblasts with cyclopamine, an antagonist of Shh signaling, inhibits Patched expression and reduces BODIPY-cholesterol efflux, while treatment with the Shh pathway agonist SAG enhances Patched protein expression and BODIPY-cholesterol efflux. We also show that over-expression of human Patched in the yeast S. cerevisiae results in a significant boost of BODIPY-cholesterol efflux. Furthermore, we demonstrate that purified Patched binds to cholesterol, and that the interaction of Shh with Patched inhibits the binding of Patched to cholesterol.Our results suggest that Patched may contribute to cholesterol efflux from cells, and to modulation of the intracellular cholesterol concentration. This activity is likely responsible for the inhibition of the enrichment of Smoothened in the plasma membrane, which is an important step in Shh pathway activation.

Knock-In Mice with NOP-eGFP Receptors Identify Receptor Cellular and Regional Localization.

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Ozawa, Akihiko; Brunori, Gloria; Mercatelli, Daniela; Wu, Jinhua; Cippitelli, Andrea; Zou, Bende; Xie, Xinmin Simon; Williams, Melissa; Zaveri, Nurulain T; Low, Sarah; Scherrer, Grégory; Kieffer, Brigitte L; Toll, Lawrence

2015-08-19

The nociceptin/orphanin FQ (NOP) receptor, the fourth member of the opioid receptor family, is involved in many processes common to the opioid receptors including pain and drug abuse. To better characterize receptor location and trafficking, knock-in mice were created by inserting the gene encoding enhanced green fluorescent protein (eGFP) into the NOP receptor gene (Oprl1) and producing mice expressing a functional NOP-eGFP C-terminal fusion in place of the native NOP receptor. The NOP-eGFP receptor was present in brain of homozygous knock-in animals in concentrations somewhat higher than in wild-type mice and was functional when tested for stimulation of [(35)S]GTPγS binding in vitro and in patch-clamp electrophysiology in dorsal root ganglia (DRG) neurons and hippocampal slices. Inhibition of morphine analgesia was equivalent when tested in knock-in and wild-type mice. Imaging revealed detailed neuroanatomy in brain, spinal cord, and DRG and was generally consistent with in vitro autoradiographic imaging of receptor location. Multicolor immunohistochemistry identified cells coexpressing various spinal cord and DRG cellular markers, as well as coexpression with μ-opioid receptors in DRG and brain regions. Both in tissue slices and primary cultures, the NOP-eGFP receptors appear throughout the cell body and in processes. These knock-in mice have NOP receptors that function both in vitro and in vivo and appear to be an exceptional tool to study receptor neuroanatomy and correlate with NOP receptor function. The NOP receptor, the fourth member of the opioid receptor family, is involved in pain, drug abuse, and a number of other CNS processes. The regional and cellular distribution has been difficult to determine due to lack of validated antibodies for immunohistochemical analysis. To provide a new tool for the investigation of receptor localization, we have produced knock-in mice with a fluorescent-tagged NOP receptor in place of the native NOP receptor. These

Involvement of Opioid System, TRPM8, and ASIC Receptors in Antinociceptive Effect of Arrabidaea brachypoda (DC) Bureau.

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Rodrigues, Vinícius Peixoto; Rocha, Cláudia Quintino da; Périco, Larissa Lucena; Santos, Raquel de Cássia Dos; Ohara, Rie; Nishijima, Catarine Massucato; Ferreira Queiroz, Emerson; Wolfender, Jean-Luc; Rocha, Lúcia Regina Machado da; Santos, Adair Roberto Soares; Vilegas, Wagner; Hiruma-Lima, Clélia Akiko

2017-11-02

Arrabidaea brachypoda (DC) Bureau is a medicinal plant found in Brazil. Known as "cipó-una", it is popularly used as a natural therapeutic agent against pain and inflammation. This study evaluated the chemical composition and antinociceptive activity of the dichloromethane fraction from the roots of A. brachypoda (DEAB) and its mechanism of action. The chemical composition was characterized by high-performance liquid chromatography, and this fraction is composed only of dimeric flavonoids. The antinociceptive effect was evaluated in formalin and hot plate tests after oral administration (10-100 mg/kg) in male Swiss mice. We also investigated the involvement of TRPV1 (transient receptor potential vanilloid 1), TRPA1 (transient receptor potential ankyrin 1), TRPM8 (transient receptor potential melastatin 8), and ASIC (acid-sensing ion channel), as well as the opioidergic, glutamatergic, and supraspinal pathways. Moreover, the nociceptive response was reduced (30 mg/kg) in the early and late phase of the formalin test. DEAB activity appears to involve the opioid system, TRPM8, and ASIC receptors, clearly showing that the DEAB alleviates acute pain in mice and suggesting the involvement of the TRPM8 and ASIC receptors and the opioid system in acute pain relief.

Involvement of NMDA receptor in low-frequency magnetic field-induced anxiety in mice.

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Salunke, Balwant P; Umathe, Sudhir N; Chavan, Jagatpalsingh G

2014-12-01

It had been reported that exposure to extremely low-frequency magnetic field (ELFMF) induces anxiety in human and rodents. Anxiety mediates via the activation of N-methyl-d-aspartate (NMDA) receptor, whereas activation of γ-aminobutyric acid (GABA) receptor attenuates the same. Hence, the present study was carried out to understand the contribution of NMDA and/or GABA receptors modulation in ELFMF-induced anxiety for which Swiss albino mice were exposed to ELFMF (50 Hz, 10 G) by subjecting them to Helmholtz coils. The exposure was for 8 h/day for 7, 30, 60, 90 and 120 days. Anxiety level was assessed in elevated plus maze, open field test and social interaction test, on 7th, 30th, 60th, 90th and 120th exposure day, respectively. Moreover, the role of GABA and glutamate in ELFMF-induced anxiety was assessed by treating mice with muscimol [0.25 mg/kg intraperitoneally (i.p.)], bicuculline (1.0 mg/kg i.p.), NMDA (15 mg/kg i.p.) and MK-801 (0.03 mg/kg i.p.), as a GABAA and NMDA receptor agonist and antagonist, respectively. Glutamate receptor agonist exacerbated while inhibitor attenuated the ELFMF-induced anxiety. In addition, levels of GABA and glutamate were determined in regions of the brain viz, cortex, striatum, hippocampus and hypothalamus. Experiments demonstrated significant elevation of GABA and glutamate levels in the hippocampus and hypothalamus. However, GABA receptor modulators did not produce significant effect on ELFMF-induced anxiety and elevated levels of GABA at tested dose. Together, these findings suggest that ELFMF significantly induced anxiety behavior, and indicated the involvement of NMDA receptor in its effect.

Adenosine receptor desensitization and trafficking.

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Mundell, Stuart; Kelly, Eamonn

2011-05-01

As with the majority of G-protein-coupled receptors, all four of the adenosine receptor subtypes are known to undergo agonist-induced regulation in the form of desensitization and trafficking. These processes can limit the ability of adenosine receptors to couple to intracellular signalling pathways and thus reduce the ability of adenosine receptor agonists as well as endogenous adenosine to produce cellular responses. In addition, since adenosine receptors couple to multiple signalling pathways, these pathways may desensitize differentially, while the desensitization of one pathway could even trigger signalling via another. Thus, the overall picture of adenosine receptor regulation can be complex. For all adenosine receptor subtypes, there is evidence to implicate arrestins in agonist-induced desensitization and trafficking, but there is also evidence for other possible forms of regulation, including second messenger-dependent kinase regulation, heterologous effects involving G proteins, and the involvement of non-clathrin trafficking pathways such as caveolae. In this review, the evidence implicating these mechanisms is summarized for each adenosine receptor subtype, and we also discuss those issues of adenosine receptor regulation that remain to be resolved as well as likely directions for future research in this field. Copyright © 2010 Elsevier B.V. All rights reserved.

Potential Involvement of P2 Receptors in the Pathological Processes of Hyperthyroidism: A Pilot Study.

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Hong, Wu; Li, Guodong; Nie, Yijun; Zou, Lifang; Zhang, Xi; Liu, Shuangmei; Li, Guilin; Xu, Hong; Zhang, Chun-Ping; Liang, Shangdong

2016-05-01

Symptoms of hyperthyroidism manifest mainly as changes in the nervous and metabolic systems. Whether P2X receptors (ionotropic ATP purinergic receptors, including P2X3 receptor and P2X7 receptor) are involved in the alterations of these disorders still remains unclear. Thus, this study aimed to assess the association of hyperthyroidism with the expression of P2X3 and P2X7 receptors and the concentrations of ATP in blood leukocytes and catecholamine. Twelve healthy subjects and twelve patients diagnosed with hyperthyroidism were recruited. Serum free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) levels had been detected by chemiluminescence method. Meanwhile, the catecholamine levels (including adrenaline, noradrenaline, and dopamine) in plasma, ATP level and P2X receptors (including P2X3 receptor and P2X7 receptor) in peripheral blood had been detected by high performance liquid chromatography, bioluminescence method, and reverse transcription polymerase chain reaction, respectively. Levels of epinephrine and norepinephrine were significantly higher in the hyperthyroidism group compared with the control group. The concentration of ATP in the hyperthyroidism group was significantly higher than its in the control group. The expression of P2X3 mRNA and P2X7 mRNA in hyperthyroidism group were significantly increased compared with those in control group. In a conclusion, there is a relationship between the elevated expression of P2X3 receptor and P2X7 receptor in peripheral blood leukocytes and high serum epinephrine and norepinephrine levels in hyperthyroidism patients. © 2016 by the Association of Clinical Scientists, Inc.

Oleocanthal Modulates Estradiol-Induced Gene Expression Involving Estrogen Receptor α.

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Keiler, Annekathrin Martina; Djiogue, Sefirin; Ehrhardt, Tino; Zierau, Oliver; Skaltsounis, Leandros; Halabalaki, Maria; Vollmer, Günter

2015-09-01

Oleocanthal is a bioactive compound from olive oil. It has attracted considerable attention as it is anti-inflammatory, antiproliferative, and has been shown to possess neuroprotective properties in vitro and in vivo. Delineated from its polyphenolic structure, the aim of this study was to characterize oleocanthal towards estrogenic properties. This might contribute to partly explain the beneficial effects described for the Mediterranean diet. Estrogenic properties of oleocanthal were assessed by different methods: a) stimulation of reporter gene activity in MVLN or RNDA cells either expressing estrogen receptor α or β, b) stimulation of luciferase reporter gene activity in U2OS osteosarcoma cells expressing estrogen receptor α or β, and c) elucidation of the impact on estradiol-induced gene expression in U2OS cells transduced with both estrogen receptors. Depending on the cell line origin, oleocanthal inhibited luciferase activity (MVLN, U2OS-estrogen receptor β) or weakly induced reporter gene activity at 10 µM in U2OS-estrogen receptor α cells. However, oleocanthal inhibited stimulation of luciferase activity by estradiol from both estrogen receptors. Oleocanthal, if given alone, did not stimulate gene expression in U2OS cells, but it significantly modulated the response of estradiol. Oleocanthal enhanced the effect of estradiol on the regulation of those genes, which are believed to be regulated through heterodimeric estrogen receptors. As the estrogenic response pattern of oleocanthal is rather unique, we compared the results obtained with oleacein. Oleocanthal binds to both estrogen receptors inducing estradiol-agonistic or antiagonistic effects depending on the cell line. Regarding regulation of gene expression in U2OS-estrogen receptor α/β cells, oleocanthal and oleacein enhanced estradiol-mediated regulation of heterodimer-regulated genes. Georg Thieme Verlag KG Stuttgart · New York.

PI3K is involved in PDGF-beta receptor upregulation post-PDGF-BB treatment in mouse HSC.

Science.gov (United States)

Lechuga, Carmen G; Hernández-Nazara, Zamira H; Hernández, Elizabeth; Bustamante, Marcia; Desierto, Gregory; Cotty, Adam; Dharker, Nachiket; Choe, Moran; Rojkind, Marcos

2006-12-01

Increased expression of PDGF-beta receptors is a landmark of hepatic stellate cell activation and transdifferentiation into myofibroblasts. However, the molecular mechanisms that regulate the fate of the receptor are lacking. Recent studies suggested that N-acetylcysteine enhances the extracellular degradation of PDGF-beta receptor by cathepsin B, thus suggesting that the absence of PDGF-beta receptors in quiescent cells is due to an active process of elimination and not to a lack of expression. In this communication we investigated further molecular mechanisms involved in PDGF-beta receptor elimination and reappearance after incubation with PDGF-BB. We showed that in culture-activated hepatic stellate cells there is no internal protein pool of receptor, that the protein is maximally phosphorylated by 5 min and completely degraded after 1 h by a lysosomal-dependent mechanism. Inhibition of receptor autophosphorylation by tyrphostin 1296 prevented its degradation, but several proteasomal inhibitors had no effect. We also showed that receptor reappearance is time and dose dependent, being more delayed in cells treated with 50 ng/ml (48 h) compared with 10 ng/ml (24 h).

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

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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.

Kinetics in Signal Transduction Pathways Involving Promiscuous Oligomerizing Receptors Can Be Determined by Receptor Specificity : Apoptosis Induction by TRAIL

NARCIS (Netherlands)

Szegezdi, Eva; van der Sloot, Almer M.; Mahalingam, Devalingam; O'Leary, Lynda; Cool, Robbert H.; Munoz, Ines G.; Montoya, Guillermo; Quax, Wim J.; de Jong, Steven; Samali, Afshin; Serrano, Luis

Here we show by computer modeling that kinetics and outcome of signal transduction in case of hetero-oligomerizing receptors of a promiscuous ligand largely depend on the relative amounts of its receptors. Promiscuous ligands can trigger the formation of nonproductive receptor complexes, which slows

Differential involvement of cortical muscarinic and NMDA receptors in short- and long-term taste aversion memory.

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Ferreira, G; Gutiérrez, R; De La Cruz, V; Bermúdez-Rattoni, F

2002-09-01

In conditioned taste aversion, an animal avoids a taste previously associated with toxic effects, and this aversive memory formation requires an intact insular cortex. In this paper, we investigated the possible differential involvement of cholinergic and glutamatergic receptors in the insular cortex in short-term memory (STM) and long-term memory (LTM) of taste aversion in rats. Taste aversion was induced by intraperitoneal administration of lithium chloride (a malaise-inducing drug) 15 min after experience with an unfamiliar taste. In order to test STM and LTM of taste aversion, taste stimulus was again presented 4 h and 72 h after lithium injection, respectively. During the acquisition, microinjection of the muscarinic antagonist, scopolamine, in the insular cortex before, but not after, the presentation of the new taste, abolished STM as well as LTM. Blockade of the NMDA receptor, in the insular cortex, by AP5 before, but not after, the presentation of the taste stimulus, impaired LTM but left STM intact. Moreover, when injected 1 h after malaise induction (i.e., during taste-illness association), AP5 disrupted both STM and LTM. These results suggest that activation of muscarinic receptors in the insular cortex is involved in the acquisition of taste memory, whereas NMDA receptors participate in taste memory consolidation. These data demonstrate that different neurochemical mechanisms subserve different memory phases. NMDA receptors are also probably involved in processing the visceral input, thus allowing subsequent taste-illness association. This indicates that in the same cortical area the same neurotransmitter system can be involved in distinct processes: taste memory consolidation vs. taste-illness association.

Involvement of Opioid System, TRPM8, and ASIC Receptors in Antinociceptive Effect of Arrabidaea brachypoda (DC Bureau

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Vinícius Peixoto Rodrigues

2017-11-01

Full Text Available Arrabidaea brachypoda (DC Bureau is a medicinal plant found in Brazil. Known as “cipó-una”, it is popularly used as a natural therapeutic agent against pain and inflammation. This study evaluated the chemical composition and antinociceptive activity of the dichloromethane fraction from the roots of A. brachypoda (DEAB and its mechanism of action. The chemical composition was characterized by high-performance liquid chromatography, and this fraction is composed only of dimeric flavonoids. The antinociceptive effect was evaluated in formalin and hot plate tests after oral administration (10–100 mg/kg in male Swiss mice. We also investigated the involvement of TRPV1 (transient receptor potential vanilloid 1, TRPA1 (transient receptor potential ankyrin 1, TRPM8 (transient receptor potential melastatin 8, and ASIC (acid-sensing ion channel, as well as the opioidergic, glutamatergic, and supraspinal pathways. Moreover, the nociceptive response was reduced (30 mg/kg in the early and late phase of the formalin test. DEAB activity appears to involve the opioid system, TRPM8, and ASIC receptors, clearly showing that the DEAB alleviates acute pain in mice and suggesting the involvement of the TRPM8 and ASIC receptors and the opioid system in acute pain relief.

FpvA receptor involvement in pyoverdine biosynthesis in Pseudomonas aeruginosa.

Science.gov (United States)

Shen, Jiangsheng; Meldrum, Allison; Poole, Keith

2002-06-01

Alignment of the Pseudomonas aeruginosa ferric pyoverdine receptor, FpvA, with similar ferric-siderophore receptors revealed that the mature protein carries an extension of ca. 70 amino acids at its N terminus, an extension shared by the ferric pseudobactin receptors of P. putida. Deletion of fpvA from the chromosome of P. aeruginosa reduced pyoverdine production in this organism, as a result of a decline in expression of genes (e.g., pvdD) associated with the biosynthesis of the pyoverdine peptide moiety. Wild-type fpvA restored pvd expression in the mutant, thereby complementing its pyoverdine deficiency, although a deletion derivative of fpvA encoding a receptor lacking the N terminus of the mature protein did not. The truncated receptor was, however, functional in pyoverdine-mediated iron uptake, as evidenced by its ability to promote pyoverdine-dependent growth in an iron-restricted medium. These data are consistent with the idea that the N-terminal extension plays a role in FpvA-mediated pyoverdine biosynthesis in P. aeruginosa.

Urokinase receptor expression involves tyrosine phosphorylation of phosphoglycerate kinase.

Science.gov (United States)

Shetty, Praveenkumar; Velusamy, Thirunavukkarasu; Bhandary, Yashodhar P; Liu, Ming C; Shetty, Sreerama

2010-02-01

The interaction of urokinase-type plasminogen activator (uPA) with its receptor, uPAR, plays a central role in several pathophysiological processes, including cancer. uPA induces its own cell surface receptor expression through stabilization of uPAR mRNA. The mechanism involves binding of a 51 nt uPAR mRNA coding sequence with phosphoglycerate kinase (PGK) to down regulate cell surface uPAR expression. Tyrosine phosphorylation of PGK mediated by uPA treatment enhances uPAR mRNA stabilization. In contrast, inhibition of tyrosine phosphorylation augments PGK binding to uPAR mRNA and attenuates uPA-induced uPAR expression. Mapping the specific peptide region of PGK indicated that its first quarter (amino acids 1-100) interacts with uPAR mRNA. To determine if uPAR expression by uPA is regulated through activation of tyrosine residues of PGK, we mutated the specific tyrosine residue and tested mutant PGK for its ability to interfere with uPAR expression. Inhibition of tyrosine phosphorylation by mutating Y76 residue abolished uPAR expression induced by uPA treatment. These findings collectively demonstrate that Y76 residue present in the first quarter of the PGK molecule is involved in lung epithelial cell surface uPAR expression. This region can effectively mimic the function of a whole PGK molecule in inhibiting tumor cell growth.

Human umbilical vein: involvement of cyclooxygenase-2 pathway in bradykinin B1 receptor-sensitized responses.

Science.gov (United States)

Errasti, A E; Rey-Ares, V; Daray, F M; Rogines-Velo, M P; Sardi, S P; Paz, C; Podestá, E J; Rothlin, R P

2001-08-01

In isolated human umbilical vein (HUV), the contractile response to des-Arg9-bradykinin (des-Arg9-BK), selective BK B1 receptor agonist, increases as a function of the incubation time. Here, we evaluated whether cyclooxygenase (COX) pathway is involved in BK B1-sensitized response obtained in 5-h incubated HUV rings. The effect of different concentrations of indomethacin, sodium salicylate, ibuprofen, meloxicam, lysine clonixinate or NS-398 administrated 30 min before concentration-response curves (CRC) was studied. All treatments produced a significant rightward shift of the CRC to des-Arg9-BK in a concentration-dependent manner, which provides pharmacological evidence that COX pathway is involved in the BK B1 responses. Moreover, in this tissue, the NS-398 pKb (5.2) observed suggests that COX-2 pathway is the most relevant. The strong correlation between published pIC50 for COX-2 and the NSAIDs' pKbs estimated further supports the hypothesis that COX-2 metabolites are involved in BK B1 receptor-mediated responses. In other rings, indomethacin (30, 100 micromol/l) or NS-398 (10, 30 micromol/l) produced a significant rightward shift of the CRC to BK, selective BK B2 agonist, and its pKbs were similar to the values to inhibit BK B1 receptor responses, suggesting that COX-2 pathway also is involved in BK B2 receptor responses. Western blot analysis shows that COX-1 and COX-2 isoenzymes are present before and after 5-h in vitro incubation and apparently COX-2 does not suffer additional induction.

Thyrotropin-luteinizing hormone/chorionic gonadotropin receptor extracellular domain chimeras as probes for thyrotropin receptor function

International Nuclear Information System (INIS)

Nagayama, Yuji; Wadsworth, H.L.; Chazenbalk, G.D.; Russo, D.; Seto, Pui; Rapoport, B.

1991-01-01

To define the sites in the extracellular domain of the human thyrotropin (TSH) receptor that are involved in TSH binding and signal transduction the authors constructed chimeric thyrotropin-luteinizing hormone/chorionic gonadotropin (TSH-LH/CG) receptors. The extracellular domain of the human TSH receptor was divided into five regions that were replaced, either singly or in various combinations, with homologous regions of the rat LH/CG receptor. The chimeric receptors were stably expressed in Chinese hamster ovary cells. The data obtained suggest that the carboxyl region of the extracellular domain (amino acid residues 261-418) and particularly the middle region (residues 171-260) play a role in signal transduction. The possibility is also raised of an interaction between the amino and carboxyl regions of the extracellular domain in the process of signal transduction. In summary, these studies suggest that the middle region and carboxyl half of the extracellular domain of the TSH receptor are involved in signal transduction and that the TSH-binding region is likely to span the entire extracellular domain, with multiple discontinuous contact sites

Molecular mechanism for the involvement of nuclear receptor FXR in HBV-associated hepatocellular carcinoma

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Yong-dong Niu

2011-08-01

Full Text Available Farnesoid X receptor (FXR, also termed nuclear receptor NR1H4 is critically involved in the regulation of nascent bile formation and bile acid enterohepatic circulation. FXR and bile acids have been shown to play roles in liver regeneration and inflammatory responses. There is increasing evidence suggesting that FXR and the FXR signaling pathway are involved in the pathophysiology of a wide range of liver diseases, such as viral hepatitis, cirrhosis, and hepatocellular carcinoma (HCC. Here we discuss the latest discoveries of FXR functions with relevance to bile acid metabolism and HBV-associated HCC. More specifically, the goal of this review is to discuss the roles of FXR and bile acids in regulating HBV replication and how disregulation of the FXR-bile acid signaling pathway is involved in HBV-associated hepatocarcinogenesis.

Involvement of histamine H1 and H2 receptors in hypothermia induced by ionizing radiation in guinea pigs

International Nuclear Information System (INIS)

Kandasamy, S.B.; Hunt, W.A.

1988-01-01

Radiation-induced hypothermia was examined in guinea pigs. Exposure to the head alone or whole-body irradiation induced hypothermia, whereas exposure of the body alone produced a small insignificant response. Systemic injection of disodium cromoglycate (a mast cell stabilizer) and cimetidine (H2-receptor antagonist) had no effect on radiation-induced hypothermia, whereas systemic and central administration of mepyramine (H1-receptor antagonist) or central administration of disodium cromoglycate or cimetidine attenuated it, indicating the involvement of central histamine through both H1 and H2 receptors in this response. Serotonin is not involved, since the serotonin antagonist methysergide had no effect on radiation-induced hypothermia. These results indicate that central histaminergic systems may be involved in radiation-induced hypothermia. 34 references, 5 figures, 2 tables

Involvement of Cholinergic and Adrenergic Receptors in Pathogenesis and Inflammatory Response Induced by Alpha-Neurotoxin Bot III of Scorpion Venom.

Science.gov (United States)

Nakib, Imene; Martin-Eauclaire, Marie-France; Laraba-Djebari, Fatima

2016-10-01

Bot III neurotoxin is the most lethal α neurotoxin purified from Buthus occitanus tunetanus scorpion venom. This toxin binds to the voltage-gated sodium channel of excitable cells and blocks its inactivation, inducing an increased release of neurotransmitters (acetylcholine and catecholamines). This study aims to elucidate the involvement of cholinergic and adrenergic receptors in pathogenesis and inflammatory response triggered by this toxin. Injection of Bot III to animals induces an increase of peroxidase activities, an imbalance of oxidative status, tissue damages in lung parenchyma, and myocardium correlated with metabolic disorders. The pretreatment with nicotine (nicotinic receptor agonist) or atropine (muscarinic receptor antagonist) protected the animals from almost all disorders caused by Bot III toxin, especially the immunological alterations. Bisoprolol administration (selective β1 adrenergic receptor antagonist) was also efficient in the protection of animals, mainly on tissue damage. Propranolol (non-selective adrenergic receptor antagonist) showed less effect. These results suggest that both cholinergic and adrenergic receptors are activated in the cardiopulmonary manifestations induced by Bot III. Indeed, the muscarinic receptor appears to be more involved than the nicotinic one, and the β1 adrenergic receptor seems to dominate the β2 receptor. These results showed also that the activation of nicotinic receptor leads to a significant protection of animals against Bot III toxin effect. These findings supply a supplementary data leading to better understanding of the mechanism triggered by scorpionic neurotoxins and suggest the use of drugs targeting these receptors, especially the nicotinic one in order to counteract the inflammatory response observed in scorpion envenomation.

Modulating Estrogen Receptor-related Receptor-α Activity 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

Adenosine Receptors and Wound Healing

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Bruce N. Cronstein

2004-01-01

Full Text Available Recent studies have demonstrated that application of topical adenosine A2A receptor agonists promotes more rapid wound closure and clinical studies are currently underway to determine the utility of topical A2A adenosine receptor agonists in the therapy of diabetic foot ulcers. The effects of adenosine A2A receptors on the cells and tissues of healing wounds have only recently been explored. We review here the known effects of adenosine A2A receptor occupancy on the cells involved in wound healing.

Potential cellular receptors involved in hepatitis C virus entry into cells

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Muellhaupt Beat

2005-04-01

Full Text Available Abstract Hepatitis C virus (HCV infects hepatocytes and leads to permanent, severe liver damage. Since the genomic sequence of HCV was determined, progress has been made towards understanding the functions of the HCV-encoded proteins and identifying the cellular receptor(s responsible for adsorption and penetration of the virus particle into the target cells. Several cellular receptors for HCV have been proposed, all of which are associated with lipid and lipoprotein metabolism. This article reviews the cellular receptors for HCV and suggests a general model for HCV entry into cells, in which lipoproteins play a crucial role.

Symposium overview: alterations in cytokine receptors by xenobiotics.

Science.gov (United States)

Cohen, M D; Schook, L B; Oppenheim, J J; Freed, B M; Rodgers, K E

1999-04-01

A symposium entitled Alterations in Cytokine Receptors by Xenobiotics was held at the 37th Annual Meeting of the Society of Toxicology (SOT) in Seattle, Washington. The symposium was sponsored by the Immunotoxicology Specialty Section of SOT and was designed to present information on the effect of several different classes of xenobiotics on various aspects of receptor function (i.e., post-receptor signal transduction of receptor expression), or the involvement of cytokine receptors in the action of the toxicant under consideration. This symposium brought together scientists in the area of receptor immunobiology whose expertise in receptor modulation encompassed those major signaling agents involved in the normal immune response, i.e., proinflammatory cytokines, chemokines, interleukins, and interferons. The following is a summary of each of the individual presentations.

Synergistic Action of Presynaptic Muscarinic Acetylcholine Receptors and Adenosine Receptors in Developmental Axonal Competition at the Neuromuscular Junction.

Science.gov (United States)

Nadal, Laura; Garcia, Neus; Hurtado, Erica; Simó, Anna; Tomàs, Marta; Lanuza, Maria Angel; Cilleros, Victor; Tomàs, Josep Maria

2016-01-01

The development of the nervous system involves the initial overproduction of synapses, which promotes connectivity. Hebbian competition between axons with different activities leads to the loss of roughly half of the overproduced elements and this refines connectivity. We used quantitative immunohistochemistry to investigate, in the postnatal day 7 (P7) to P9 neuromuscular junctions, the involvement of muscarinic receptors (muscarinic acetylcholine autoreceptors and the M1, M2, and M4 subtypes) and adenosine receptors (A1 and A2A subtypes) in the control of axonal elimination after the mouse levator auris longus muscle had been exposed to selective antagonists in vivo. In a previous study we analyzed the role of each of the individual receptors. Here we investigate the additive or occlusive effects of their inhibitors and thus the existence of synergistic activity between the receptors. The main results show that the A2A, M1, M4, and A1 receptors (in this order of ability) delayed axonal elimination at P7. M4 produces some occlusion of the M1 pathway and some addition to the A1 pathway, which suggests that they cooperate. M2 receptors may modulate (by allowing a permissive action) the other receptors, mainly M4 and A1. The continued action of these receptors (now including M2 but not M4) finally promotes axonal loss at P9. All 4 receptors (M2, M1, A1, and A2A, in this order of ability) are necessary. The M4 receptor (which in itself does not affect axon loss) seems to modulate the other receptors. We found a synergistic action between the M1, A1, and A2A receptors, which show an additive effect, whereas the potent M2 effect is largely independent of the other receptors (though can be modulated by M4). At P9, there is a full mutual dependence between the A1 and A2A receptors in regulating axon loss. In summary, postnatal axonal elimination is a regulated multireceptor mechanism that involves the cooperation of several muscarinic and adenosine receptor subtypes. �

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...

Possible Relevance of Receptor-Receptor Interactions between Viral- and Host-Coded Receptors for Viral-Induced Disease

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Luigi F. Agnati

2007-01-01

Full Text Available It has been demonstrated that some viruses, such as the cytomegalovirus, code for G-protein coupled receptors not only to elude the immune system, but also to redirect cellular signaling in the receptor networks of the host cells. In view of the existence of receptor-receptor interactions, the hypothesis is introduced that these viral-coded receptors not only operate as constitutively active monomers, but also can affect other receptor function by interacting with receptors of the host cell. Furthermore, it is suggested that viruses could also insert not single receptors (monomers, but clusters of receptors (receptor mosaics, altering the cell metabolism in a profound way. The prevention of viral receptor-induced changes in host receptor networks may give rise to novel antiviral drugs that counteract viral-induced disease.

Evaluation of Analgesic Activity of Papaver libanoticum Extract in Mice: Involvement of Opioids Receptors

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Mohamad Ali Hijazi

2017-01-01

Full Text Available Papaver libanoticum is an endemic plant to Lebanese region (family Papaveraceae that has not been investigated before. The present study aimed to explore the analgesic activity of dried ethanolic extract of Papaver libanoticum (PLE using tail flick, hot plate, and acetic acid induced writhing models in mice. The involvement of opioid receptors in the analgesic mechanism was investigated using naloxone antagonism. Results demonstrated that PLE exhibited a potent dose dependent analgesic activity in all tested models for analgesia. The analgesic effect involved activation of opioid receptors in the central nervous system, where both spinal and supraspinal components might be involved. The time course for analgesia revealed maximum activity after three hours in both tail flick and hot plate methods, which was prolonged to 24 hours. Metabolites of PLE could be responsible for activation of opioid receptors. The EC50 of PLE was 79 and 50 mg/kg in tail flick and hot plate tests, respectively. The total coverage of analgesia by PLE was double that of morphine in both tests. In conclusion, PLE proved to have opioid agonistic activity with a novel feature of slow and prolonged effect. The present study could add a potential tool in the armaments of opioid drugs as a natural potent analgesic and for treatment of opioid withdrawal syndrome.

Neurobeachin regulates neurotransmitter receptor trafficking to synapses

NARCIS (Netherlands)

Nair, R.; Lauks, J.; Jung, S; Cooke, N.E.; de Wit, H.; Brose, N.; Kilimann, M.W.; Verhage, M.; Rhee, J.

2013-01-01

The surface density of neurotransmitter receptors at synapses is a key determinant of synaptic efficacy. Synaptic receptor accumulation is regulated by the transport, postsynaptic anchoring, and turnover of receptors, involving multiple trafficking, sorting, motor, and scaffold proteins. We found

Androgen Receptor Involvement in Rat Amelogenesis: An Additional Way for Endocrine-Disrupting Chemicals to Affect Enamel Synthesis.

Science.gov (United States)

Jedeon, Katia; Loiodice, Sophia; Salhi, Khaled; Le Normand, Manon; Houari, Sophia; Chaloyard, Jessica; Berdal, Ariane; Babajko, Sylvie

2016-11-01

Endocrine-disrupting chemicals (EDCs) that interfere with the steroid axis can affect amelogenesis, leading to enamel hypomineralization similar to that of molar incisor hypomineralization, a recently described enamel disease. We investigated the sex steroid receptors that may mediate the effects of EDCs during rat amelogenesis. The expression of androgen receptor (AR), estrogen receptor (ER)-α, and progesterone receptor was dependent on the stage of ameloblast differentiation, whereas ERβ remained undetectable. AR was the only receptor selectively expressed in ameloblasts involved in final enamel mineralization. AR nuclear translocation and induction of androgen-responsive element-containing promoter activity upon T treatment, demonstrated ameloblast responsiveness to androgens. T regulated the expression of genes involved in enamel mineralization such as KLK4, amelotin, SLC26A4, and SLC5A8 but not the expression of genes encoding matrix proteins, which determine enamel thickness. Vinclozolin and to a lesser extent bisphenol A, two antiandrogenic EDCs that cause enamel defects, counteracted the actions of T. In conclusion, we show, for the first time, the following: 1) ameloblasts express AR; 2) the androgen signaling pathway is involved in the enamel mineralization process; and 3) EDCs with antiandrogenic effects inhibit AR activity and preferentially affect amelogenesis in male rats. Their action, through the AR pathway, may specifically and irreversibly affect enamel, potentially leading to the use of dental defects as a biomarker of exposure to environmental pollutants. These results are consistent with the steroid hormones affecting ameloblasts, raising the issue of the hormonal influence on amelogenesis and possible sexual dimorphism in enamel quality.

AMPK is involved in the regulation of incretin receptors expression in pancreatic islets under a low glucose concentration.

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Kazuki Tajima

Full Text Available The precise role of AMP-activated protein kinase (AMPK, a target of metformin, in pancreatic β cells remains controversial, even though metformin was recently shown to enhance the expression of incretin receptors (GLP-1 and GIP receptors in pancreatic β cells. In this study, we investigated the effect of AMPK in the regulation of incretin receptors expression in pancreatic islets. The phosphorylation of AMPK in the mouse islets was decreased by increasing glucose concentrations. We showed the expression of incretin receptors in bell-shaped response to glucose. Expression of the incretin receptors in the isolated islets showed higher levels under a medium glucose concentration (11.1 mM than that under a low glucose concentration (2.8 mM, but was suppressed under a high glucose concentration (22.2 mM. Both treatment with an AMPK inhibitor and DN-AMPK expression produced a significant increase of the incretin receptors expression under a low glucose concentration. By contrast, in hyperglycemic db/db islets, the enhancing effect of the AMPK inhibitor on the expression of incretin receptors was diminished under a low glucose concentration. Taken together, AMPK is involved in the regulation of incretin receptors expression in pancreatic islets under a low glucose concentration.

Melatonin Receptor Genes in Vertebrates

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Hua Dong Yin

2013-05-01

Full Text Available Melatonin receptors are members of the G protein-coupled receptor (GPCR family. Three genes for melatonin receptors have been cloned. The MT1 (or Mel1a or MTNR1A and MT2 (or Mel1b or MTNR1B receptor subtypes are present in humans and other mammals, while an additional melatonin receptor subtype, Mel1c (or MTNR1C, has been identified in fish, amphibians and birds. Another melatonin related orphan receptor, GPR50, which does not bind melatonin, is found exclusively in mammals. The hormone melatonin is secreted primarily by the pineal gland, with highest levels occurring during the dark period of a circadian cycle. This hormone acts systemically in numerous organs. In the brain, it is involved in the regulation of various neural and endocrine processes, and it readjusts the circadian pacemaker, the suprachiasmatic nucleus. This article reviews recent studies of gene organization, expression, evolution and mutations of melatonin receptor genes of vertebrates. Gene polymorphisms reveal that numerous mutations are associated with diseases and disorders. The phylogenetic analysis of receptor genes indicates that GPR50 is an outgroup to all other melatonin receptor sequences. GPR50 may have separated from a melatonin receptor ancestor before the split between MTNR1C and the MTNR1A/B ancestor.

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...

Secretory phospholipase A2-mediated neuronal cell death involves glutamate ionotropic receptors

DEFF Research Database (Denmark)

Kolko, Miriam; de Turco, Elena B; Diemer, Nils Henrik

2002-01-01

To define the significance of glutamate ionotropic receptors in sPLA -mediated neuronal cell death we used the NMDA receptor antagonist MK-801 and the AMPA receptor antagonist PNQX. In primary neuronal cell cultures both MK-801 and PNQX inhibited sPLA - and glutamate-induced neuronal death. [ H...

Possible involvement of α- and β-receptors in the natural colour change and the MSH-induced dispersion in Xenopus laevis in vivo

NARCIS (Netherlands)

Brouwer, E.; Veerdonk, F.C.G. van de

Participation of adrenergic receptors in the darkening reaction has been demonstrated in Xenopus laevis in vivo. Blockade of the β-receptors inhibited adaptation to a black background as well as the artificially MSH-induced dispersion. α-Receptors could not be proved to be involved in the dispersion

Angiotensin receptors and norepinephrine neuromodulation: implications of functional coupling.

Science.gov (United States)

Gelband, C H; Sumners, C; Lu, D; Raizada, M K

1998-02-27

The objective of this review is to examine the role of neuronal angiotensin II (Ang II) receptors in vitro. Two types of G protein-coupled Ang II receptors have been identified in cardiovascularly relevant areas of the brain: the AT1 and the AT2. We have utilized neurons in culture to study the signaling mechanisms of AT1 and AT2 receptors. Neuronal AT1 receptors are involved in norepinephrine (NE) neuromodulation. NE neuromodulation can be either evoked or enhanced. Evoked NE neuromodulation involves AT1 receptor-mediated, losartan-dependent, rapid NE release, inhibition of K+ channels and stimulation of Ca2+ channels. AT1 receptor-mediated enhanced NE neuromodulation involves the Ras-Raf-MAP kinase cascade and ultimately leads to an increase in NE transporter, tyrosine hydroxylase and dopamine beta-hydroxylase mRNA transcription. Neuronal AT2 receptors signal via a Gi protein and are coupled to activation of PP2A and PLA2 and stimulation of K+ channels. Finally, putative cross-talk pathways between AT1 and AT2 receptors will be discussed.

Somatostatin receptors

DEFF Research Database (Denmark)

Møller, Lars Neisig; Stidsen, Carsten Enggaard; Hartmann, Bolette

2003-01-01

functional units, receptors co-operate. The total receptor apparatus of individual cell types is composed of different-ligand receptors (e.g. SRIF and non-SRIF receptors) and co-expressed receptor subtypes (e.g. sst(2) and sst(5) receptors) in characteristic proportions. In other words, levels of individual......-peptides, receptor agonists and antagonists. Relatively long half lives, as compared to those of the endogenous ligands, have been paramount from the outset. Motivated by theoretical puzzles or the shortcomings of present-day diagnostics and therapy, investigators have also aimed to produce subtype...

Pharmacological significance of the interplay between angiotensin receptors: MAS receptors as putative final mediators of the effects elicited by angiotensin AT1 receptors antagonists.

Science.gov (United States)

Pernomian, Larissa; Pernomian, Laena; Gomes, Mayara S; da Silva, Carlos H T P

2015-12-15

The interplay between angiotensin AT1 receptors and MAS receptors relies on several inward regulatory mechanisms from renin-angiotensin system (RAS) including the functional crosstalk between angiotensin II and angiotensin-(1-7), the competitive AT1 antagonism exhibited by angiotensin-(1-7), the antagonist feature assigned to AT1/MAS heterodimerization on AT1 signaling and the AT1-mediated downregulation of angiotensin-converting enzyme 2 (ACE2). Recently, such interplay has acquired an important significance to RAS Pharmacology since a few studies have supporting strong evidences that MAS receptors mediate the effects elicited by AT1 antagonists. The present Perspective provides an overview of the regulatory mechanisms involving AT1 and MAS receptors, their significance to RAS Pharmacology and the future directions on the interplay between angiotensin receptors. Copyright © 2015 Elsevier B.V. All rights reserved.

NK-1 receptor antagonists as anti-cancer drugs

Indian Academy of Sciences (India)

The substance P (SP)/neurokinin (NK)-1 receptor system plays an important role in cancer. SP promotes the proliferation of tumour cells, angiogenesis and the migration of tumour cells. We review the involvement of SP, the NK-1 receptor and NK-1 receptor antagonists in cancer. Tumour cells overexpress NK-1 receptors, ...

The First Fifteen Years of Steroid Receptor Research in Zebrafish; Characterization and Functional Analysis of the Receptors

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Marcel J. M. Schaaf

2017-07-01

Full Text Available Steroid hormones regulate a wide range of processes in our body, and their effects are mediated by steroid receptors. In addition to their physiological role, these receptors mediate the effects of endocrine disrupting chemicals (EDCs and are widely used targets for dugs involved in the treatment of numerous diseases, ranging from cancer to inflammatory disorders. Over the last fifteen years, the zebrafish has increasingly been used as an animal model in steroid receptor research. Orthologues of all human steroid receptor genes appear to be present in zebrafish. All zebrafish steroid receptors have been characterized in detail, and their expression patterns have been analyzed. Functional studies have been performed using morpholino knockdown of receptor expression and zebrafish lines carrying mutations in one of their steroid receptor genes. To investigate the activity of the receptors in vivo, specific zebrafish reporter lines have been developed, and transcriptomic studies have been carried out to identify biomarkers for steroid receptor action. In this review, an overview of research on steroid receptors in zebrafish is presented, and it is concluded that further exploitation of the possibilities of the zebrafish model system will contribute significantly to the advancement of steroid receptor research in the next decade.

Internalization of G-protein-coupled receptors: Implication in receptor function, physiology and diseases.

Science.gov (United States)

Calebiro, Davide; Godbole, Amod

2018-04-01

G protein-coupled receptors (GPCRs) are the largest family of membrane receptors and mediate the effects of numerous hormones and neurotransmitters. The nearly 1000 GPCRs encoded by the human genome regulate virtually all physiological functions and are implicated in the pathogenesis of prevalent human diseases such as thyroid disorders, hypertension or Parkinson's disease. As a result, 30-50% of all currently prescribed drugs are targeting these receptors. Once activated, GPCRs induce signals at the cell surface. This is often followed by internalization, a process that results in the transfer of receptors from the plasma membrane to membranes of the endosomal compartment. Internalization was initially thought to be mainly implicated in signal desensitization, a mechanism of adaptation to prolonged receptor stimulation. However, several unexpected functions have subsequently emerged. Most notably, accumulating evidence indicates that internalization can induce prolonged receptor signaling on intracellular membranes, which is apparently required for at least some biological effects of hormones like TSH, LH and adrenaline. These findings reveal an even stronger connection between receptor internalization and signaling than previously thought. Whereas new studies are just beginning to reveal an important physiological role for GPCR signaling after internalization and ways to exploit it for therapeutic purposes, future investigations will be required to explore its involvement in human disease. Copyright © 2018 Elsevier Ltd. All rights reserved.

CysLT2 receptor activation is involved in LTC4-induced lung air-trapping in guinea pigs.

Science.gov (United States)

Sekioka, Tomohiko; Kadode, Michiaki; Yonetomi, Yasuo; Kamiya, Akihiro; Fujita, Manabu; Nabe, Takeshi; Kawabata, Kazuhito

2017-01-05

CysLT 1 receptors are known to be involved in the pathogenesis of asthma. However, the functional roles of CysLT 2 receptors in this condition have not been determined. The purpose of this study is to develop an experimental model of CysLT 2 receptor-mediated LTC 4 -induced lung air-trapping in guinea pigs and use this model to clarify the mechanism underlying response to such trapping. Because LTC 4 is rapidly converted to LTD 4 by γ-glutamyltranspeptidase (γ-GTP) under physiological conditions, S-hexyl GSH was used as a γ-GTP inhibitor. In anesthetized artificially ventilated guinea pigs with no S-hexyl GSH treatment, i.v. LTC 4 -induced bronchoconstriction was almost completely inhibited by montelukast, a CysLT 1 receptor antagonist, but not by BayCysLT 2 RA, a CysLT 2 receptor antagonist. The inhibitory effect of montelukast was diminished by treatment with S-hexyl GSH, whereas the effect of BayCysLT 2 RA was enhanced with increasing dose of S-hexyl GSH. Macroscopic and histological examination of lung tissue isolated from LTC 4 -/S-hexyl-GSH-treated guinea pigs revealed air-trapping expansion, particularly at the alveolar site. Inhaled LTC 4 in conscious guinea pigs treated with S-hexyl GSH increased both airway resistance and airway hyperinflation. On the other hand, LTC 4 -induced air-trapping was only partially suppressed by treatment with the bronchodilator salmeterol. Although montelukast inhibition of LTC 4 -induced air-trapping was weak, treatment with BayCysLT 2 RA resulted in complete suppression of this air-trapping. Furthermore, BayCysLT 2 RA completely suppressed LTC 4 -induced airway vascular hyperpermeability. In conclusion, we found in this study that CysLT 2 receptors mediate LTC 4 -induced bronchoconstriction and air-trapping in S-hexyl GSH-treated guinea pigs. It is therefore believed that CysLT 2 receptors contribute to asthmatic response involving air-trapping. Copyright © 2016 Elsevier B.V. All rights reserved.

The collagen receptor uPARAP/Endo180

DEFF Research Database (Denmark)

Engelholm, Lars H; Ingvarsen, Signe; Jürgensen, Henrik J

2009-01-01

The uPAR-associated protein (uPARAP/Endo180), a type-1 membrane protein belonging to the mannose receptor family, is an endocytic receptor for collagen. Through this endocytic function, the protein takes part in a previously unrecognized mechanism of collagen turnover. uPARAP/Endo180 can bind...... and internalize both intact and partially degraded collagens. In some turnover pathways, the function of the receptor probably involves an interplay with certain matrix-degrading proteases whereas, in other physiological processes, redundant mechanisms involving both endocytic and pericellular collagenolysis seem...... in collagen breakdown seems to be involved in invasive tumor growth Udgivelsesdato: 2009...

Opioid modulation of immunocompetence: Receptor characterization and second messenger involvement

International Nuclear Information System (INIS)

Hemmick, L.M.

1989-01-01

The purpose of this thesis was to examine the effects of opioids on several indices of immunocompetence, determined the receptor specificity of these effects, and ascertain whether the actions of opioids on lymphocytes could be correlated with activation of second messenger systems. By measuring 45 Ca 2+ uptake into lymphocytes, it was demonstrated that β-endorphin 1-31 (β-END 1-31) enhanced rat thymocyte Ca 2+ uptake in response to concanavalin A (Con A) but not phytohemagglutinin (PHA). Related opioid peptides and alkaloids were unable to mimic the effect, and naloxone did not block it, suggesting that β-END 1-31 acted by binding to specific, non-opioid receptors on the thymocytes. Rat splenocyte Con A-stimulated Ca 2+ uptake was not affected by β-END 1-31. β-END 1-31 did not affect basal Ca 2+ uptake by either cell type. Using [ 3 H]thymidine uptake as an index of lymphocyte proliferation, β-END 1-31 and several related opioid peptides reversed prostaglandin E 1 (PGE 1 ) suppression of rat lymph node cell Con A- and PHA-stimulated proliferation. Naloxone did not block the reversal. β-END 1-31 was unable to reverse forskolin and cholera toxin suppression of proliferation, indicating that the lowering of cyclic AMP levels was not the mechanism involved. Verapamil inhibition of proliferation was also not reversed by β-END 1-31, suggesting that promotion of Ca 2+ influx was not a major mechanism involved

Reconstruction of the Chemotaxis Receptor-Kinase Assembly

International Nuclear Information System (INIS)

Park, S.; Borbat, P.; Gonzalez-Bonet, G.; Bhatnagar, J.; Pollard, A.; Freed, J.; Bilwes, A.; Crane, B.

2006-01-01

In bacterial chemotaxis, an assembly of transmembrane receptors, the CheA histidine kinase and the adaptor protein CheW processes environmental stimuli to regulate motility. The structure of a Thermotoga maritima receptor cytoplasmic domain defines CheA interaction regions and metal ion-coordinating charge centers that undergo chemical modification to tune receptor response. Dimeric CheA-CheW, defined by crystallography and pulsed ESR, positions two CheWs to form a cleft that is lined with residues important for receptor interactions and sized to clamp one receptor dimer. CheW residues involved in kinase activation map to interfaces that orient the CheW clamps. CheA regulatory domains associate in crystals through conserved hydrophobic surfaces. Such CheA self-contacts align the CheW receptor clamps for binding receptor tips. Linking layers of ternary complexes with close-packed receptors generates a lattice with reasonable component ratios, cooperative interactions among receptors and accessible sites for modification enzymes

Androgen Receptor Signaling in Bladder Cancer

OpenAIRE

Li, Peng; Chen, Jinbo; Miyamoto, Hiroshi

2017-01-01

Emerging preclinical findings have indicated that steroid hormone receptor signaling plays an important role in bladder cancer outgrowth. In particular, androgen-mediated androgen receptor signals have been shown to correlate with the promotion of tumor development and progression, which may clearly explain some sex-specific differences in bladder cancer. This review summarizes and discusses the available data, suggesting the involvement of androgens and/or the androgen receptor pathways in u...

Presynaptic G Protein-Coupled Receptors: Gatekeepers of Addiction?

Directory of Open Access Journals (Sweden)

Kari A Johnson

2016-11-01

Full Text Available Drug abuse and addiction cause widespread social and public health problems, and the neurobiology underlying drug actions and drug use and abuse is an area of intensive research. Drugs of abuse alter synaptic transmission, and these actions contribute to acute intoxication as well as the chronic effects of abused substances. Transmission at most mammalian synapses involves neurotransmitter activation of two receptor subtypes, ligand-gated ion channels that mediate fast synaptic responses, and G protein-coupled receptors (GPCRs that have slower neuromodulatory actions. The GPCRs represent a large proportion of neurotransmitter receptors involved in almost all facets of nervous system function. In addition, these receptors are targets for many pharmacotherapeutic agents. Drugs of abuse directly or indirectly affect neuromodulation mediated by GPCRs, with important consequences for intoxication, drug taking and responses to prolonged drug exposure, withdrawal and addiction. Among the GPCRs are several subtypes involved in presynaptic inhibition, most of which are coupled to the Gi/o class of G protein. There is increasing evidence that these presynaptic Gi/o-coupled GPCRs have important roles in the actions of drugs of abuse, as well as behaviors related to these drugs. This topic will be reviewed, with particular emphasis on receptors for three neurotransmitters, dopamine (D1- and D2-like receptors, endocannabinoids (CB1 receptors and glutamate (group II metabotropic glutamate (mGlu receptors. The focus is on recent evidence from laboratory animal models (and some evidence in humans implicating these receptors in the acute and chronic effects of numerous abused drugs, as well as in the control of drug seeking and taking. The ability of drugs targeting these receptors to modify drug seeking behavior has raised the possibility of using compounds targeting these receptors for addiction pharmacotherapy. This topic is also discussed, with emphasis on

Insulin receptors

International Nuclear Information System (INIS)

Kahn, C.R.; Harrison, L.C.

1988-01-01

This book contains the proceedings on insulin receptors. Part A: Methods for the study of structure and function. Topics covered include: Method for purification and labeling of insulin receptors, the insulin receptor kinase, and insulin receptors on special tissues

Primary structure and functional characterization of a Drosophila dopamine receptor with high homology to human D1/5 receptors.

Science.gov (United States)

Gotzes, F; Balfanz, S; Baumann, A

1994-01-01

Members of the superfamily of G-protein coupled receptors share significant similarities in sequence and transmembrane architecture. We have isolated a Drosophila homologue of the mammalian dopamine receptor family using a low stringency hybridization approach. The deduced amino acid sequence is approximately 70% homologous to the human D1/D5 receptors. When expressed in HEK 293 cells, the Drosophila receptor stimulates cAMP production in response to dopamine application. This effect was mimicked by SKF 38393, a specific D1 receptor agonist, but inhibited by dopaminergic antagonists such as butaclamol and flupentixol. In situ hybridization revealed that the Drosophila dopamine receptor is highly expressed in the somata of the optic lobes. This suggests that the receptor might be involved in the processing of visual information and/or visual learning in invertebrates.

Recent Progress in Understanding Subtype Specific Regulation of NMDA Receptors by G Protein Coupled Receptors (GPCRs

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Kai Yang

2014-02-01

Full Text Available G Protein Coupled Receptors (GPCRs are the largest family of receptors whose ligands constitute nearly a third of prescription drugs in the market. They are widely involved in diverse physiological functions including learning and memory. NMDA receptors (NMDARs, which belong to the ionotropic glutamate receptor family, are likewise ubiquitously expressed in the central nervous system (CNS and play a pivotal role in learning and memory. Despite its critical contribution to physiological and pathophysiological processes, few pharmacological interventions aimed directly at regulating NMDAR function have been developed to date. However, it is well established that NMDAR function is precisely regulated by cellular signalling cascades recruited downstream of G protein coupled receptor (GPCR stimulation. Accordingly, the downstream regulation of NMDARs likely represents an important determinant of outcome following treatment with neuropsychiatric agents that target selected GPCRs. Importantly, the functional consequence of such regulation on NMDAR function varies, based not only on the identity of the GPCR, but also on the cell type in which relevant receptors are expressed. Indeed, the mechanisms responsible for regulating NMDARs by GPCRs involve numerous intracellular signalling molecules and regulatory proteins that vary from one cell type to another. In the present article, we highlight recent findings from studies that have uncovered novel mechanisms by which selected GPCRs regulate NMDAR function and consequently NMDAR-dependent plasticity.

Involvement of spinal NR2B-containing NMDA receptors in oxaliplatin-induced mechanical allodynia in rats

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Yano Takahisa

2011-01-01

Full Text Available Abstract Background Oxaliplatin is a platinum-based chemotherapy drug characterized by the development of acute and chronic peripheral neuropathies. The chronic neuropathy is a dose-limiting toxicity. We previously reported that repeated administration of oxaliplatin induced cold hyperalgesia in the early phase and mechanical allodynia in the late phase in rats. In the present study, we investigated the involvement of NR2B-containing N-methyl-D-aspartate (NMDA receptors in oxaliplatin-induced mechanical allodynia in rats. Results Repeated administration of oxaliplatin (4 mg/kg, i.p., twice a week caused mechanical allodynia in the fourth week, which was reversed by intrathecal injection of MK-801 (10 nmol and memantine (1 μmol, NMDA receptor antagonists. Similarly, selective NR2B antagonists Ro25-6981 (300 nmol, i.t. and ifenprodil (50 mg/kg, p.o. significantly attenuated the oxaliplatin-induced pain behavior. In addition, the expression of NR2B protein and mRNA in the rat spinal cord was increased by oxaliplatin on Day 25 (late phase but not on Day 5 (early phase. Moreover, we examined the involvement of nitric oxide synthase (NOS as a downstream target of NMDA receptor. L-NAME, a non-selective NOS inhibitor, and 7-nitroindazole, a neuronal NOS (nNOS inhibitor, significantly suppressed the oxaliplatin-induced pain behavior. The intensity of NADPH diaphorase staining, a histochemical marker for NOS, in the superficial layer of spinal dorsal horn was obviously increased by oxaliplatin, and this increased intensity was reversed by intrathecal injection of Ro25-6981. Conclusion These results indicated that spinal NR2B-containing NMDA receptors are involved in the oxaliplatin-induced mechanical allodynia.

Differential Involvement of Amygdala and Cortical NMDA Receptors Activation upon Encoding in Odor Fear Memory

Science.gov (United States)

Hegoburu, Chloé; Parrot, Sandrine; Ferreira, Guilaume; Mouly, Anne-Marie

2014-01-01

Although the basolateral amygdala (BLA) plays a crucial role for the acquisition of fear memories, sensory cortices are involved in their long-term storage in rats. However, the time course of their respective involvement has received little investigation. Here we assessed the role of the glutamatergic N-methyl-D-aspartate (NMDA) receptors in the…

Opioid modulation of immunocompetence: Receptor characterization and second messenger involvement

Energy Technology Data Exchange (ETDEWEB)

Hemmick, L.M.

1989-01-01

The purpose of this thesis was to examine the effects of opioids on several indices of immunocompetence, determined the receptor specificity of these effects, and ascertain whether the actions of opioids on lymphocytes could be correlated with activation of second messenger systems. By measuring {sup 45}Ca{sup 2+} uptake into lymphocytes, it was demonstrated that {beta}-endorphin 1-31 ({beta}-END 1-31) enhanced rat thymocyte Ca{sup 2+} uptake in response to concanavalin A (Con A) but not phytohemagglutinin (PHA). Related opioid peptides and alkaloids were unable to mimic the effect, and naloxone did not block it, suggesting that {beta}-END 1-31 acted by binding to specific, non-opioid receptors on the thymocytes. Rat splenocyte Con A-stimulated Ca{sup 2+} uptake was not affected by {beta}-END 1-31. {beta}-END 1-31 did not affect basal Ca{sup 2+} uptake by either cell type. Using ({sup 3}H)thymidine uptake as an index of lymphocyte proliferation, {beta}-END 1-31 and several related opioid peptides reversed prostaglandin E{sub 1} (PGE{sub 1}) suppression of rat lymph node cell Con A- and PHA-stimulated proliferation. Naloxone did not block the reversal. {beta}-END 1-31 was unable to reverse forskolin and cholera toxin suppression of proliferation, indicating that the lowering of cyclic AMP levels was not the mechanism involved. Verapamil inhibition of proliferation was also not reversed by {beta}-END 1-31, suggesting that promotion of Ca{sup 2+} influx was not a major mechanism involved.

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

Science.gov (United States)

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

1993-06-11

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

Identification of G Protein-Coupled Receptors (GPCRs in Primary Cilia and Their Possible Involvement in Body Weight Control.

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Yoshihiro Omori

Full Text Available Primary cilia are sensory organelles that harbor various receptors such as G protein-coupled receptors (GPCRs. We analyzed subcellular localization of 138 non-odorant GPCRs. We transfected GPCR expression vectors into NIH3T3 cells, induced ciliogenesis by serum starvation, and observed subcellular localization of GPCRs by immunofluorescent staining. We found that several GPCRs whose ligands are involved in feeding behavior, including prolactin-releasing hormone receptor (PRLHR, neuropeptide FF receptor 1 (NPFFR1, and neuromedin U receptor 1 (NMUR1, localized to the primary cilia. In addition, we found that a short form of dopamine receptor D2 (DRD2S is efficiently transported to the primary cilia, while a long form of dopamine receptor D2 (DRD2L is rarely transported to the primary cilia. Using an anti-Prlhr antibody, we found that Prlhr localized to the cilia on the surface of the third ventricle in the vicinity of the hypothalamic periventricular nucleus. We generated the Npy2r-Cre transgenic mouse line in which Cre-recombinase is expressed under the control of the promoter of Npy2r encoding a ciliary GPCR. By mating Npy2r-Cre mice with Ift80 flox mice, we generated Ift80 conditional knockout (CKO mice in which Npy2r-positive cilia were diminished in number. We found that Ift80 CKO mice exhibited a body weight increase. Our results suggest that Npy2r-positive cilia are important for body weight control.

Identification of G Protein-Coupled Receptors (GPCRs) in Primary Cilia and Their Possible Involvement in Body Weight Control.

Science.gov (United States)

Omori, Yoshihiro; Chaya, Taro; Yoshida, Satoyo; Irie, Shoichi; Tsujii, Toshinori; Furukawa, Takahisa

2015-01-01

Primary cilia are sensory organelles that harbor various receptors such as G protein-coupled receptors (GPCRs). We analyzed subcellular localization of 138 non-odorant GPCRs. We transfected GPCR expression vectors into NIH3T3 cells, induced ciliogenesis by serum starvation, and observed subcellular localization of GPCRs by immunofluorescent staining. We found that several GPCRs whose ligands are involved in feeding behavior, including prolactin-releasing hormone receptor (PRLHR), neuropeptide FF receptor 1 (NPFFR1), and neuromedin U receptor 1 (NMUR1), localized to the primary cilia. In addition, we found that a short form of dopamine receptor D2 (DRD2S) is efficiently transported to the primary cilia, while a long form of dopamine receptor D2 (DRD2L) is rarely transported to the primary cilia. Using an anti-Prlhr antibody, we found that Prlhr localized to the cilia on the surface of the third ventricle in the vicinity of the hypothalamic periventricular nucleus. We generated the Npy2r-Cre transgenic mouse line in which Cre-recombinase is expressed under the control of the promoter of Npy2r encoding a ciliary GPCR. By mating Npy2r-Cre mice with Ift80 flox mice, we generated Ift80 conditional knockout (CKO) mice in which Npy2r-positive cilia were diminished in number. We found that Ift80 CKO mice exhibited a body weight increase. Our results suggest that Npy2r-positive cilia are important for body weight control.

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...

Expression of melatonin receptors in arteries involved in thermoregulation

International Nuclear Information System (INIS)

Viswanathan, M.; Laitinen, J.T.; Saavedra, J.M.

1990-01-01

Melatonin binding sites were localized and characterized in the vasculature of the rat by using the melatonin analogue 2-[125I]iodomelatonin (125I-melatonin) and quantitative in vitro autoradiography. The expression of these sites was restricted to the caudal artery and to the arteries that form the circle of Willis at the base of the brain. The arterial 125I-melatonin binding was stable, saturable, and reversible. Saturation studies revealed that the binding represented a single class of high-affinity binding sites with a dissociation constant (Kd) of 3.4 x 10(-11) M in the anterior cerebral artery and 1.05 x 10(-10) M in the caudal artery. The binding capacities (Bmax) in these arteries were 19 and 15 fmol/mg of protein, respectively. The relative order of potency of indoles for inhibition of 125I-melatonin binding at these sites was typical of a melatonin receptor: 2-iodomelatonin greater than melatonin greater than N-acetylserotonin much much greater than 5-hydroxytryptamine. Norepinephrine-induced contraction of the caudal artery in vitro was significantly prolonged and potentiated by melatonin in a concentration-dependent manner, suggesting that these arterial binding sites are functional melatonin receptors. Neither primary steps in smooth muscle contraction (inositol phospholipid hydrolysis) nor relaxation (adenylate cyclase activation) were affected by melatonin. Melatonin, through its action on the tone of these arteries, may cause circulatory adjustments in these arteries, which are believed to be involved in thermoregulation

{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.

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.

Secretin receptor involvement in prion-infected cells and animals.

Science.gov (United States)

Kimura, Tomohiro; Nishizawa, Keiko; Oguma, Ayumi; Nishimura, Yuki; Sakasegawa, Yuji; Teruya, Kenta; Nishijima, Ichiko; Doh-ura, Katsumi

2015-07-08

The cellular mechanisms behind prion biosynthesis and metabolism remain unclear. Here we show that secretin signaling via the secretin receptor regulates abnormal prion protein formation in prion-infected cells. Animal studies demonstrate that secretin receptor deficiency slightly, but significantly, prolongs incubation time in female but not male mice. This gender-specificity is consistent with our finding that prion-infected cells are derived from females. Therefore, our results provide initial insights into the reasons why age of disease onset in certain prion diseases is reported to occur slightly earlier in females than males. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Characterization of the 5-HT1A receptor of the honeybee (Apis mellifera) and involvement of serotonin in phototactic behavior.

Science.gov (United States)

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

2010-07-01

Serotonin plays a key role in modulating various physiological and behavioral processes in both protostomes and deuterostomes. The vast majority of serotonin receptors belong to the superfamily of G-protein-coupled receptors. We report the cloning of a cDNA from the honeybee (Am5-ht1A) sharing high similarity with members of the 5-HT(1) receptor class. Activation of Am5-HT(1A) by serotonin inhibited the production of cAMP in a dose-dependent manner (EC(50) = 16.9 nM). Am5-HT(1A) was highly expressed in brain regions known to be involved in visual information processing. Using in vivo pharmacology, we could demonstrate that Am5-HT(1A) receptor ligands had a strong impact on the phototactic behavior of individual bees. The data presented here mark the first comprehensive study-from gene to behavior-of a 5-HT(1A) receptor in the honeybee, paving the way for the eventual elucidation of additional roles of this receptor subtype in the physiology and behavior of this social insect.

Sensing of Blood Pressure Increase by Transient Receptor Potential Vanilloid 1 Receptors on Baroreceptors

OpenAIRE

Sun, Hao; Li, De-Pei; Chen, Shao-Rui; Hittelman, Walter N.; Pan, Hui-Lin

2009-01-01

The arterial baroreceptor is critically involved in the autonomic regulation of homoeostasis. The transient receptor potential vanilloid 1 (TRPV1) receptor is expressed on both somatic and visceral sensory neurons. Here, we examined the TRPV1 innervation of baroreceptive pathways and its functional significance in the baroreflex. Resiniferatoxin (RTX), an ultrapotent analog of capsaicin, was used to ablate TRPV1-expressing afferent neurons and fibers in adult rats. Immunofluorescence labeling...

Androgen Receptor Signaling in Bladder Cancer

Science.gov (United States)

Li, Peng; Chen, Jinbo; Miyamoto, Hiroshi

2017-01-01

Emerging preclinical findings have indicated that steroid hormone receptor signaling plays an important role in bladder cancer outgrowth. In particular, androgen-mediated androgen receptor signals have been shown to correlate with the promotion of tumor development and progression, which may clearly explain some sex-specific differences in bladder cancer. This review summarizes and discusses the available data, suggesting the involvement of androgens and/or the androgen receptor pathways in urothelial carcinogenesis as well as tumor growth. While the precise mechanisms of the functions of the androgen receptor in urothelial cells remain far from being fully understood, current evidence may offer chemopreventive or therapeutic options, using androgen deprivation therapy, in patients with bladder cancer. PMID:28241422

Androgen Receptor Signaling in Bladder Cancer

Directory of Open Access Journals (Sweden)

Peng Li

2017-02-01

Full Text Available Emerging preclinical findings have indicated that steroid hormone receptor signaling plays an important role in bladder cancer outgrowth. In particular, androgen-mediated androgen receptor signals have been shown to correlate with the promotion of tumor development and progression, which may clearly explain some sex-specific differences in bladder cancer. This review summarizes and discusses the available data, suggesting the involvement of androgens and/or the androgen receptor pathways in urothelial carcinogenesis as well as tumor growth. While the precise mechanisms of the functions of the androgen receptor in urothelial cells remain far from being fully understood, current evidence may offer chemopreventive or therapeutic options, using androgen deprivation therapy, in patients with bladder cancer.

The interleukin-4 receptor: signal transduction by a hematopoietin receptor.

Science.gov (United States)

Keegan, A D; Pierce, J H

1994-02-01

Over the last several years, the receptors for numerous cytokines have been molecularly characterized. Analysis of their amino acid sequences shows that some of these receptors bear certain motifs in their extracellular domains that define a family of receptors called the Hematopoietin receptor superfamily. Significant advances in characterizing the structure, function, and mechanisms of signal transduction have been made for several members of this family. The purpose of this review is to discuss the recent advances made for one of the family members, the interleukin (IL) 4 receptor. Other receptor systems have recently been reviewed elsewhere. The IL-4 receptor consists of, at the minimum, the cloned 140 kDa IL-4-binding chain with the potential for associating with other chains. The IL-4 receptor transduces its signal by activating a tyrosine kinase that phosphorylates cellular substrates, including the receptor itself, and the 170 kDa substrate called 4PS. Phosphorylated 4PS interacts with the SH2 domain of the enzyme PI-3'-kinase and increases its enzymatic activity. These early events in the IL-4 receptor initiated signaling pathway may trigger a series of signals that will ultimately lead to an IL-4 specific biologic outcome.

Opioid receptor desensitization: mechanisms and its link to tolerance

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Stéphane eAllouche

2014-12-01

Full Text Available Opioid receptors are part of the class A of G-protein coupled receptors and the target of the opiates, the most powerful analgesic molecules used in clinic. During a protracted use, a tolerance to analgesic effect develops resulting in a reduction of the effectiveness. So understanding mechanisms of tolerance is a great challenge and may help to find new strategies to tackle this side effect. This review will summarize receptor-related mechanisms that could underlie tolerance especially receptor desensitization. We will focus on the latest data obtained on molecular mechanisms involved in opioid receptor desensitization: phosphorylation, receptor uncoupling, internalization and post-endocytic fate of the receptor.

Involvement of the Retinoid X Receptor Ligand in the Anti-Inflammatory Effect Induced by Peroxisome Proliferator-Activated Receptor Agonist In Vivo

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Atsuki Yamamoto

2011-01-01

Full Text Available Peroxisome proliferator-activated receptor γ (PPARγ forms a heterodimeric DNA-binding complex with retinoid X receptors (RXRs. It has been reported that the effect of the PPAR agonist is reduced in hepatocyte RXR-deficient mice. Therefore, it is suggested that the endogenous RXR ligand is involved in the PPARγ agonist-induced anti-inflammatory effect. However, the participation of the RXR ligand in the PPARγ-induced anti-inflammatory effect is unknown. Here, we investigated the influence of RXR antagonist on the anti-inflammatory effect of PPARγ agonist pioglitazone in carrageenan test. In addition, we also examined the influence of PPAR antagonist on the anti-inflammatory effect induced by RXR agonist NEt-3IP. The RXR antagonist suppressed the antiedema effect of PPARγ agonist. In addition, the anti-inflammatory effect of RXR agonist was suppressed by PPARγ antagonist. PPARγ agonist-induced anti-inflammatory effects were reversed by the RXR antagonist. Thus, we showed that the endogenous RXR ligand might contribute to the PPARγ agonist-induced anti-inflammatory effect.

Membrane Trafficking of Death Receptors: Implications on Signalling

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Wulf Schneider-Brachert

2013-07-01

Full Text Available Death receptors were initially recognised as potent inducers of apoptotic cell death and soon ambitious attempts were made to exploit selective ignition of controlled cellular suicide as therapeutic strategy in malignant diseases. However, the complexity of death receptor signalling has increased substantially during recent years. Beyond activation of the apoptotic cascade, involvement in a variety of cellular processes including inflammation, proliferation and immune response was recognised. Mechanistically, these findings raised the question how multipurpose receptors can ensure selective activation of a particular pathway. A growing body of evidence points to an elegant spatiotemporal regulation of composition and assembly of the receptor-associated signalling complex. Upon ligand binding, receptor recruitment in specialized membrane compartments, formation of receptor-ligand clusters and internalisation processes constitute key regulatory elements. In this review, we will summarise the current concepts of death receptor trafficking and its implications on receptor-associated signalling events.

Intracellular postsynaptic cannabinoid receptors link thyrotropin-releasing hormone receptors to TRPC-like channels in thalamic paraventricular nucleus neurons.

Science.gov (United States)

Zhang, L; Kolaj, M; Renaud, L P

2015-12-17

In rat thalamic paraventricular nucleus of thalamus (PVT) neurons, activation of thyrotropin-releasing hormone (TRH) receptors enhances excitability via concurrent decrease in G protein-coupled inwardly-rectifying potassium (GIRK)-like and activation of transient receptor potential cation (TRPC)4/5-like cationic conductances. An exploration of intracellular signaling pathways revealed the TRH-induced current to be insensitive to phosphatidylinositol-specific phospholipase C (PI-PLC) inhibitors, but reduced by D609, an inhibitor of phosphatidylcholine-specific PLC (PC-PLC). A corresponding change in the I-V relationship implied suppression of the cationic component of the TRH-induced current. Diacylglycerol (DAG) is a product of the hydrolysis of PC. Studies focused on the isolated cationic component of the TRH-induced response revealed a reduction by RHC80267, an inhibitor of DAG lipase, the enzyme involved in the hydrolysis of DAG to the endocannabinoid 2-arachidonoylglycerol (2-AG). Further investigation revealed enhancement of the cationic component in the presence of either JZL184 or WWL70, inhibitors of enzymes involved in the hydrolysis of 2-AG. A decrease in the TRH-induced response was noted in the presence of rimonabant or SR144528, membrane permeable CB1 and CB2 receptor antagonists, respectively. A decrease in the TRH-induced current by intracellular, but not by bath application of the membrane impermeable peptide hemopressin, selective for CB1 receptors, suggests a postsynaptic intracellular localization of these receptors. The TRH-induced current was increased in the presence of arachidonyl-2'-chloroethylamide (ACEA) or JWH133, CB1 and CB2 receptor agonists, respectively. The PI3-kinase inhibitor LY294002, known to inhibit TRPC translocation, decreased the response to TRH. In addition, a TRH-induced enhancement of the low-threshold spike was prevented by both rimonabant, and SR144528. TRH had no influence on excitatory or inhibitory miniature

Microglia P2Y13 Receptors Prevent Astrocyte Proliferation Mediated by P2Y1 Receptors

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Clara Quintas

2018-05-01

Full Text Available Cerebral inflammation is a common feature of several neurodegenerative diseases that requires a fine interplay between astrocytes and microglia to acquire appropriate phenotypes for an efficient response to neuronal damage. During brain inflammation, ATP is massively released into the extracellular medium and converted into ADP. Both nucleotides acting on P2 receptors, modulate astrogliosis through mechanisms involving microglia-astrocytes communication. In previous studies, primary cultures of astrocytes and co-cultures of astrocytes and microglia were used to investigate the influence of microglia on astroglial proliferation induced by ADPβS, a stable ADP analog. In astrocyte cultures, ADPβS increased cell proliferation through activation of P2Y1 and P2Y12 receptors, an effect abolished in co-cultures (of astrocytes with ∼12.5% microglia. The possibility that the loss of the ADPβS-mediated effect could have been caused by a microglia-induced degradation of ADPβS or by a preferential microglial localization of P2Y1 or P2Y12 receptors was excluded. Since ADPβS also activates P2Y13 receptors, the contribution of microglial P2Y13 receptors to prevent the proliferative effect of ADPβS in co-cultures was investigated. The results obtained indicate that P2Y13 receptors are low expressed in astrocytes and mainly expressed in microglia. Furthermore, in co-cultures, ADPβS induced astroglial proliferation in the presence of the selective P2Y13 antagonist MRS 2211 (3 μM and of the selective P2Y12 antagonist AR-C66096 (0.1 μM, suggesting that activation of microglial P2Y12 and P2Y13 receptors may induce the release of messengers that inhibit astroglial proliferation mediated by P2Y1,12 receptors. In this microglia-astrocyte paracrine communication, P2Y12 receptors exert opposite effects in astroglial proliferation as a result of its cellular localization: cooperating in astrocytes with P2Y1 receptors to directly stimulate proliferation and in

The LDL receptor.

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Goldstein, Joseph L; Brown, Michael S

2009-04-01

In this article, the history of the LDL receptor is recounted by its codiscoverers. Their early work on the LDL receptor explained a genetic cause of heart attacks and led to new ways of thinking about cholesterol metabolism. The LDL receptor discovery also introduced three general concepts to cell biology: receptor-mediated endocytosis, receptor recycling, and feedback regulation of receptors. The latter concept provides the mechanism by which statins selectively lower plasma LDL, reducing heart attacks and prolonging life.

Structural Insights into Selective Ligand-Receptor Interactions Leading to Receptor Inactivation Utilizing Selective Melanocortin 3 Receptor Antagonists.

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Cai, Minying; Marelli, Udaya Kiran; Mertz, Blake; Beck, Johannes G; Opperer, Florian; Rechenmacher, Florian; Kessler, Horst; Hruby, Victor J

2017-08-15

Systematic N-methylated derivatives of the melanocortin receptor ligand, SHU9119, lead to multiple binding and functional selectivity toward melanocortin receptors. However, the relationship between N-methylation-induced conformational changes in the peptide backbone and side chains and melanocortin receptor selectivity is still unknown. We conducted comprehensive conformational studies in solution of two selective antagonists of the third isoform of the melanocortin receptor (hMC3R), namely, Ac-Nle-c[Asp-NMe-His 6 -d-Nal(2') 7 -NMe-Arg 8 -Trp 9 -Lys]-NH 2 (15) and Ac-Nle-c[Asp-His 6 -d-Nal(2') 7 -NMe-Arg 8 -NMe-Trp 9 -NMe-Lys]-NH 2 (17). It is known that the pharmacophore (His 6 -DNal 7 -Arg 8 -Trp 9 ) of the SHU-9119 peptides occupies a β II-turn-like region with the turn centered about DNal 7 -Arg 8 . The analogues with hMC3R selectivity showed distinct differences in the spatial arrangement of the Trp 9 side chains. In addition to our NMR studies, we also carried out molecular-level interaction studies of these two peptides at the homology model of hMC3R. Earlier chimeric human melanocortin 3 receptor studies revealed insights regarding the binding and functional sites of hMC3R selectivity. Upon docking of peptides 15 and 17 to the binding pocket of hMC3R, it was revealed that Arg 8 and Trp 9 side chains are involved in a majority of the interactions with the receptor. While Arg 8 forms polar contacts with D154 and D158 of hMC3R, Trp 9 utilizes π-π stacking interactions with F295 and F298, located on the transmembrane domain of hMC3R. It is hypothesized that as the frequency of Trp 9 -hMC3R interactions decrease, antagonistic activity increases. The absence of any interactions of the N-methyl groups with hMC3R suggests that their primary function is to modulate backbone conformations of the ligands.

Involvement of endothelin and ET(A) endothelin receptor in mechanical allodynia in mice given orthotopic melanoma inoculation.

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Fujita, Masahide; Andoh, Tsugunobu; Saiki, Ikuo; Kuraishi, Yasushi

2008-02-01

We investigated whether endothelin (ET) would be involved in skin cancer pain in mice. Orthotopic inoculation of B16-BL6 melanoma cells into the plantar region of the hind paw produced marked mechanical allodynia in C57BL/6 mice. Intraplantar injections of the ET(A)-receptor antagonist BQ-123 (0.3 - 3 nmol/site), but not the ET(B)-receptor antagonist BQ-788 (1 and 3 nmol/site), inhibited mechanical allodynia in mice with grown melanoma. In naive mice, an intraplantar injection of tumor extract (1 and 3 mg/site), which was prepared from the grown melanoma in the paw, produced mechanical allodynia, which was inhibited by BQ-123 and BQ-788 at doses of 3 and 10 nmol/site. An intraplantar injection of ET-1 (1 and 10 pmol/site) elicited licking behavior, which was increased in the melanoma-bearing hind paw. BQ-123 (3 and 10 nmol/site) inhibited licking induced by ET-1 (10 pmol/site). The level of mRNA of ET(A), but not ET(B), receptor, was significantly increased in the dorsal root ganglia on the inoculated side. Cultured B16-BL6 cells contained ET, and the melanoma mass increased the concentration of ET as it grew bigger. These results suggest that ET-1 and ET(A) receptor are at least partly involved in the induction of pain induced by melanoma cell inoculation.

Involvement of hippocampal NMDA receptors in retrieval of spontaneous object recognition memory in rats.

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Iwamura, Etsushi; Yamada, Kazuo; Ichitani, Yukio

2016-07-01

The involvement of hippocampal N-methyl-d-aspartate (NMDA) receptors in the retrieval process of spontaneous object recognition memory was investigated. The spontaneous object recognition test consisted of three phases. In the sample phase, rats were exposed to two identical objects several (2-5) times in the arena. After the sample phase, various lengths of delay intervals (24h-6 weeks) were inserted (delay phase). In the test phase in which both the familiar and the novel objects were placed in the arena, rats' novel object exploration behavior under the hippocampal treatment of NMDA receptor antagonist, AP5, or vehicle was observed. With 5 exposure sessions in the sample phase (experiment 1), AP5 treatment in the test phase significantly decreased discrimination ratio when the delay was 3 weeks but not when it was one week. On the other hand, with 2 exposure sessions in the sample phase (experiment 2) in which even vehicle-injected control animals could not discriminate the novel object from the familiar one with a 3 week delay, AP5 treatment significantly decreased discrimination ratio when the delay was one week, but not when it was 24h. Additional experiment (experiment 3) showed that the hippocampal treatment of an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, NBQX, decreased discrimination ratio with all delay intervals tested (24h-3 weeks). Results suggest that hippocampal NMDA receptors play an important role in the retrieval of spontaneous object recognition memory especially when the memory trace weakens. Copyright © 2016. Published by Elsevier B.V.

Atypical chemokine receptors in cancer: friends or foes?

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Massara, Matteo; Bonavita, Ornella; Mantovani, Alberto; Locati, Massimo; Bonecchi, Raffaella

2016-06-01

The chemokine system is a fundamental component of cancer-related inflammation involved in all stages of cancer development. It controls not only leukocyte infiltration in primary tumors but also angiogenesis, cancer cell proliferation, and migration to metastatic sites. Atypical chemokine receptors are a new, emerging class of regulators of the chemokine system. They control chemokine bioavailability by scavenging, transporting, or storing chemokines. They can also regulate the activity of canonical chemokine receptors with which they share the ligands by forming heterodimers or by modulating their expression levels or signaling activity. Here, we summarize recent results about the role of these receptors (atypical chemokine receptor 1/Duffy antigen receptor for chemokine, atypical chemokine receptor 2/D6, atypical chemokine receptor 3/CXC-chemokine receptor 7, and atypical chemokine receptor 4/CC-chemokine receptor-like 1) on the tumorigenesis process, indicating that their effects are strictly dependent on the cell type on which they are expressed and on their coexpression with other chemokine receptors. Indeed, atypical chemokine receptors inhibit tumor growth and progression through their activity as negative regulators of chemokine bioavailability, whereas, on the contrary, they can promote tumorigenesis when they regulate the signaling of other chemokine receptors, such as CXC-chemokine receptor 4. Thus, atypical chemokine receptors are key components of the regulatory network of inflammation and immunity in cancer and may have a major effect on anti-inflammatory and immunotherapeutic strategies. © Society for Leukocyte Biology.

Involvement of α₂-adrenoceptors, imidazoline, and endothelin-A receptors in the effect of agmatine on morphine and oxycodone-induced hypothermia in mice.

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Bhalla, Shaifali; Andurkar, Shridhar V; Gulati, Anil

2013-10-01

Potentiation of opioid analgesia by endothelin-A (ET(A)) receptor antagonist, BMS182874, and imidazoline receptor/α₂-adrenoceptor agonists such as clonidine and agmatine are well known. It is also known that agmatine blocks morphine hyperthermia in rats. However, the effect of agmatine on morphine or oxycodone hypothermia in mice is unknown. The present study was carried out to study the role of α₂-adrenoceptors, imidazoline, and ET(A) receptors in morphine and oxycodone hypothermia in mice. Body temperature was determined over 6 h in male Swiss Webster mice treated with morphine, oxycodone, agmatine, and combination of agmatine with morphine or oxycodone. Yohimbine, idazoxan, and BMS182874 were used to determine involvement of α₂-adrenoceptors, imidazoline, and ET(A) receptors, respectively. Morphine and oxycodone produced significant hypothermia that was not affected by α₂-adrenoceptor antagonist yohimbine, imidazoline receptor/α₂ adrenoceptor antagonist idazoxan, or ET(A) receptor antagonist, BMS182874. Agmatine did not produce hypothermia; however, it blocked oxycodone but not morphine-induced hypothermia. Agmatine-induced blockade of oxycodone hypothermia was inhibited by idazoxan and yohimbine. The blockade by idazoxan was more pronounced compared with yohimbine. Combined administration of BMS182874 and agmatine did not produce changes in body temperature in mice. However, when BMS182874 was administered along with agmatine and oxycodone, it blocked agmatine-induced reversal of oxycodone hypothermia. This is the first report demonstrating that agmatine does not affect morphine hypothermia in mice, but reverses oxycodone hypothermia. Imidazoline receptors and α₂-adrenoceptors are involved in agmatine-induced reversal of oxycodone hypothermia. Our findings also suggest that ET(A) receptors may be involved in blockade of oxycodone hypothermia by agmatine. © 2012 The Authors Fundamental and Clinical Pharmacology © 2012 Société Française de

Mediator-dependent Nuclear Receptor Functions

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Chen, Wei; Roeder, Robert

2011-01-01

As gene-specific transcription factors, nuclear hormone receptors are broadly involved in many important biological processes. Their function on target genes requires the stepwise assembly of different coactivator complexes that facilitate chromatin remodeling and subsequent preinitiation complex (PIC) formation and function. Mediator has proved to be a crucial, and general, nuclear receptor-interacting coactivator, with demonstrated functions in transcription steps ranging from chromatin remodeling to subsequent PIC formation and function. Here we discuss (i) our current understanding of pathways that nuclear receptors and other interacting cofactors employ to recruit Mediator to target gene enhancers and promoters, including conditional requirements for the strong NR-Mediator interactions mediated by the NR AF2 domain and the MED1 LXXLLL motifs and (ii) mechanisms by which Mediator acts to transmit signals from enhancer-bound nuclear receptors to the general transcription machinery at core promoters to effect PIC formation and function. PMID:21854863

Receptor-like proteins involved in plant disease resistance

NARCIS (Netherlands)

Kruijt, M.; Kock, de M.J.D.; Wit, de P.J.G.M.

2005-01-01

Race-specific resistance in plants against microbial pathogens is governed by several distinct classes of resistance (R) genes. This review focuses on the class that consists of the plasma membrane-bound leucine-rich repeat proteins known as receptor-like proteins (RLPs). The first isolated

Palmitoylation as a Functional Regulator of Neurotransmitter Receptors

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Vladimir S. Naumenko

2018-01-01

Full Text Available The majority of neuronal proteins involved in cellular signaling undergo different posttranslational modifications significantly affecting their functions. One of these modifications is a covalent attachment of a 16-C palmitic acid to one or more cysteine residues (S-palmitoylation within the target protein. Palmitoylation is a reversible modification, and repeated cycles of palmitoylation/depalmitoylation might be critically involved in the regulation of multiple signaling processes. Palmitoylation also represents a common posttranslational modification of the neurotransmitter receptors, including G protein-coupled receptors (GPCRs and ligand-gated ion channels (LICs. From the functional point of view, palmitoylation affects a wide span of neurotransmitter receptors activities including their trafficking, sorting, stability, residence lifetime at the cell surface, endocytosis, recycling, and synaptic clustering. This review summarizes the current knowledge on the palmitoylation of neurotransmitter receptors and its role in the regulation of receptors functions as well as in the control of different kinds of physiological and pathological behavior.

The Memory-Impairing Effects of Septal GABA Receptor Activation Involve GABAergic Septo-Hippocampal Projection Neurons

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Krebs-Kraft, Desiree L.; Wheeler, Marina G.; Parent, Marise B.

2007-01-01

Septal infusions of the [gamma]-aminobutyric acid (GABA)[subscript A] agonist muscimol impair memory, and the effect likely involves the hippocampus. GABA[subscript A] receptors are present on the perikarya of cholinergic and GABAergic septo-hippocampal (SH) projections. The current experiments determined whether GABAergic SH projections are…

Do orphan G-protein-coupled receptors have ligand-independent functions? New insights from receptor heterodimers

OpenAIRE

Levoye, Angélique; Dam, Julie; Ayoub, Mohammed A; Guillaume, Jean-Luc; Jockers, Ralf

2006-01-01

G-protein-coupled receptors (GPCRs) are important drug targets and are involved in virtually every biological process. However, there are still more than 140 orphan GPCRs, and deciphering their function remains a priority for fundamental and clinical research. Research on orphan GPCRs has concentrated mainly on the identification of their natural ligands, whereas recent data suggest additional ligand-independent functions for these receptors. This emerging concept is connected with the observ...

β-Adrenergic receptor-mediated suppression of interleukin 2 receptors in human lymphocytes

International Nuclear Information System (INIS)

Feldman, R.D.; Hunninghake, G.W.; McArdle, W.L.

1987-01-01

Adrenergic receptor agonists are know to attenuate the proliferative response of human lymphocytes after activation; however, their mechanism of action is unknown. Since expression of interleukin 2 (IL-2) receptors is a prerequisite for proliferation, the effect of β-adrenergic receptor agonists on lymphocyte IL-2 receptors was studied on both mitogen-stimulated lymphocytes and IL-2-dependent T lymphocyte cell lines. In both cell types the β-adrenergic receptor agonist isoproterenol blocked the expression of IL-2 receptors, as determined with the IL-2 receptor anti-TAC antibody. To determine the effect of β-adrenergic agonists on expression of the high affinity IL-2 receptors, [ 125 I]IL-2 binding studies were performed at concentrations selective for high affinity sites. No significant effect of β-adrenergic agonists on high affinity IL-2 receptor sites could be detected. The data demonstrate that β-adrenergic receptor agonists down-regulate IL-2 receptors primarily affecting low affinity sites

The ABA receptors -- we report you decide.

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McCourt, Peter; Creelman, Robert

2008-10-01

The plant hormone abscisic acid (ABA) has been implicated in a variety of physiological responses ranging from seed dormancy to stomatal conductance. Recently, three groups have reported the molecular identification of three disparate ABA receptors. Unlike the identification of other hormone receptors, in these three cases high affinity binding to ABA rather than the isolation of ABA insensitive mutants led to these receptor genes. Interestingly, two of the receptors encode genes involved in floral timing and chlorophyll biosynthesis, which are not considered traditional ABA responses. And the third receptor has been clouded in issues of its molecular identity. To clearly determine the roles of these genes in ABA perception it will require placing of these ABA-binding proteins into the rich ABA physiological context that has built up over the years.

Dynamic mobility of functional GABAA receptors at inhibitory synapses.

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Thomas, Philip; Mortensen, Martin; Hosie, Alastair M; Smart, Trevor G

2005-07-01

Importing functional GABAA receptors into synapses is fundamental for establishing and maintaining inhibitory transmission and for controlling neuronal excitability. By introducing a binding site for an irreversible inhibitor into the GABAA receptor alpha1 subunit channel lining region that can be accessed only when the receptor is activated, we have determined the dynamics of receptor mobility between synaptic and extrasynaptic locations in hippocampal pyramidal neurons. We demonstrate that the cell surface GABAA receptor population shows no fast recovery after irreversible inhibition. In contrast, after selective inhibition, the synaptic receptor population rapidly recovers by the import of new functional entities within minutes. The trafficking pathways that promote rapid importation of synaptic receptors do not involve insertion from intracellular pools, but reflect receptor diffusion within the plane of the membrane. This process offers the synapse a rapid mechanism to replenish functional GABAA receptors at inhibitory synapses and a means to control synaptic efficacy.

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.

Quantitative receptor radioautography in the study of receptor-receptor interactions in the nucleus tractus solitarii

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Fior-Chadi D.R.

1998-01-01

Full Text Available The nucleus tractus solitarii (NTS in the dorsomedial medulla comprises a wide range of neuropeptides and biogenic amines. Several of them are related to mechanisms of central blood pressure control. Angiotensin II (Ang II, neuropeptide Y (NPY and noradrenaline (NA are found in the NTS cells, as well as their receptors. Based on this observation we have evaluated the modulatory effect of these peptide receptors on a2-adrenoceptors in the NTS. Using quantitative receptor radioautography, we observed that NPY and Ang II receptors decreased the affinity of a2-adrenoceptors for their agonists in the NTS of the rat. Cardiovascular experiments agreed with the in vitro data. Coinjection of a threshold dose of Ang II or of the NPY agonists together with an ED50 dose of adrenergic agonists such as NA, adrenaline and clonidine counteracted the depressor effect produced by the a2-agonist in the NTS. The results provide evidence for the existence of an antagonistic interaction between Ang II at1 receptors and NPY receptor subtypes with the a2-adrenoceptors in the NTS. This receptor interaction may reduce the transduction over the a2-adrenoceptors which can be important in central cardiovascular regulation and in the development of hypertension

Adenosine Receptors in Developing and Adult Mouse Neuromuscular Junctions and Functional Links With Other Metabotropic Receptor Pathways.

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Tomàs, Josep; Garcia, Neus; Lanuza, Maria A; Santafé, Manel M; Tomàs, Marta; Nadal, Laura; Hurtado, Erica; Simó-Ollé, Anna; Cilleros-Mañé, Víctor; Just-Borràs, Laia

2018-01-01

In the last few years, we have studied the presence and involvement in synaptogenesis and mature transmitter release of the adenosine autoreceptors (AR) in the mammalian neuromuscular junction (NMJ). Here, we review and bring together the previously published data to emphasize the relevance of these receptors for developmental axonal competition, synaptic loss and mature NMJ functional modulation. However, in addition to AR, activity-dependent mediators originating from any of the three cells that make the synapse (nerve, muscle, and glial cells) cross the extracellular cleft to generate signals in target metabotropic receptors. Thus, the integrated interpretation of the complementary function of all these receptors is needed. We previously studied, in the NMJ, the links of AR with mAChR and the neurotrophin receptor TrkB in the control of synapse elimination and transmitter release. We conclude that AR cooperate with these receptors through synergistic and antagonistic effects in the developmental synapse elimination process. In the adult NMJ, this cooperation is manifested so as that the functional integrity of a given receptor group depends on the other receptors operating normally (i.e., the functional integrity of mAChR depends on AR operating normally). These observations underlie the relevance of AR in the NMJ function.

Adenosine Receptors in Developing and Adult Mouse Neuromuscular Junctions and Functional Links With Other Metabotropic Receptor Pathways

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Josep Tomàs

2018-04-01

Full Text Available In the last few years, we have studied the presence and involvement in synaptogenesis and mature transmitter release of the adenosine autoreceptors (AR in the mammalian neuromuscular junction (NMJ. Here, we review and bring together the previously published data to emphasize the relevance of these receptors for developmental axonal competition, synaptic loss and mature NMJ functional modulation. However, in addition to AR, activity-dependent mediators originating from any of the three cells that make the synapse (nerve, muscle, and glial cells cross the extracellular cleft to generate signals in target metabotropic receptors. Thus, the integrated interpretation of the complementary function of all these receptors is needed. We previously studied, in the NMJ, the links of AR with mAChR and the neurotrophin receptor TrkB in the control of synapse elimination and transmitter release. We conclude that AR cooperate with these receptors through synergistic and antagonistic effects in the developmental synapse elimination process. In the adult NMJ, this cooperation is manifested so as that the functional integrity of a given receptor group depends on the other receptors operating normally (i.e., the functional integrity of mAChR depends on AR operating normally. These observations underlie the relevance of AR in the NMJ function.

Involvement of growth factors and their receptors in radon-induced rat lung tumors

International Nuclear Information System (INIS)

Leung, F.C.; Dagle, G.E.; Cross, F.T.

1992-01-01

In this paper we examine the role of growth factors (GF) and their receptors (GFR) in radon-induced rat lung tumors. Inhalation exposure of radon and its daughters induced lung tumors in rats, but the molecule/cellular mechanisms are not known. Recent evidence suggests that GF/GFR play a critical role in the growth and development of lung cancer in humans and animals. We have developed immunocytochemical methods for identifying sites of production and action of GF/GFR at the cellular level; for example, the avidin-biotin horseradish peroxidase technique. In radon-induced rat epidermoid carcinomas, epidermal growth factor (EGF), EGF-receptors (EGF-R), transforming growth factor alpha (TGF-α), and bombesin were found to be abnormally expressed. These abnormal expressions, mainly associated with epidermoid carcinomas of the lung, were not found in any other lung tumor types. Our data suggest that EGF, EGF-R, TGF-α, and bombesin are involved in radon oncogenesis in rat lungs, especially in epidermoid carcinomas, possibly through the autocrine/paracrine pathway

Stereochemistry of charged nitrogen-aromatic interactions and its involvement in ligand-receptor binding

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Verdonk, Marcel L.; Boks, Gertjan J.; Kooijman, Huub; Kanters, Jan A.; Kroon, Jan

1993-04-01

Recently, new evidence was found for the involvement of charged nitrogen-aromatic interactions in ligand-receptor binding. In this study we report two favourable orientations of a phenyl ring with respect to a R-N+(CH3)3 group, based on crystal structure statistics from the Cambridge Structural Database. In the first orientation, the phenyl ring is situated in between the substituents at about 4.5 Å from the nitrogen atom, and the ring is approximately oriented on the sphere around the nitrogen atom. In the second orientation, the phenyl ring is situated in the same direction as one of the N-C bonds at about 6.0 Å from the nitrogen atom, and the ring is tilted with respect to the sphere around the nitrogen atom. The same two orientations were also found in the crystal structures of three ligand-receptor complexes, which implies that these orientations probably play a major role in molecular recognition mechanisms.

Purinergic receptors are involved in tooth-pulp evoked nocifensive behavior and brainstem neuronal activity

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Sessle Barry J

2010-09-01

Full Text Available Abstract Background To evaluate whether P2X receptors are involved in responses to noxious pulp stimulation, the P2X3 and P2X2/3 receptor agonist α,β-methyleneATP (α,β-meATP was applied to the molar tooth pulp and nocifensive behavior and extracellular-signal regulated kinase (ERK phosphorylation in trigeminal spinal subnucleus caudalis (Vc, trigeminal spinal subnucleus interpolaris (Vi, upper cervical spinal cord (C1/C2 and paratrigeminal nucleus (Pa5 neurons were analyzed in rats. Results Genioglossus (GG muscle activity was evoked by pulpal application of 100 mM α,β-meATP and was significantly larger than GG activity following vehicle (phosphate-buffered saline PBS application (p 1, P2X3 and, P2X2/3 antagonist. A large number of pERK-LI cells were expressed in the Vc, Vi/Vc, C1/C2 and Pa5 at 5 min following pulpal application of 100 mM α,β-meATP compared to PBS application to the pulp (p Conclusions The present findings suggest that activation of P2X3 and P2X2/3 receptors in the tooth pulp is sufficient to elicit nociceptive behavioral responses and trigeminal brainstem neuronal activity.

Brain nicotinic acetylcholine receptors are involved in stress-induced potentiation of nicotine reward in rats.

Science.gov (United States)

Javadi, Parastoo; Rezayof, Ameneh; Sardari, Maryam; Ghasemzadeh, Zahra

2017-07-01

The aim of the present study was to examine the possible role of nicotinic acetylcholine receptors of the dorsal hippocampus (CA1 regions), the medial prefrontal cortex or the basolateral amygdala in the effect of acute or sub-chronic stress on nicotine-induced conditioned place preference. Our results indicated that subcutaneous administration of nicotine (0.2 mg/kg) induced significant conditioned place preference. Exposure to acute or sub-chronic elevated platform stress potentiated the response of an ineffective dose of nicotine. Pre-conditioning intra-CA1 (0.5-4 µg/rat) or intra-medial prefrontal cortex (0.2-0.3 µg/rat) microinjection of mecamylamine (a non-selective nicotinic acetylcholine receptor antagonist) reversed acute stress-induced potentiation of nicotine reward as measured in the conditioned place preference paradigm. By contrast, pre-conditioning intra-basolateral amygdala microinjection of mecamylamine (4 µg/rat) potentiated the effects of acute stress on nicotine reward. Our findings also showed that intra-CA1 or intra-medial prefrontal cortex, but not intra-basolateral amygdala, microinjection of mecamylamine (4 µg/rat) prevented the effect of sub-chronic stress on nicotine reward. These findings suggest that exposure to elevated platform stress potentiates the rewarding effect of nicotine which may be associated with the involvement of nicotinic acetylcholine receptors. It seems that there is a different contribution of the basolateral amygdala, the medial prefrontal cortex or the CA1 nicotinic acetylcholine receptors in stress-induced potentiation of nicotine-induced conditioned place preference.

Identification of amino acids involved in histamine potentiation of GABA(A receptors

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Ulrike eThiel

2015-05-01

Full Text Available Histamine is a neurotransmitter involved in a number of physiological and neuronal functions. In mammals, such as humans and rodents, the histaminergic neurons found in the tuberomamillary nucleus (TMN project widely throughout the central nervous system (CNS. Histamine acts as positive modulator of GABA(A receptors (GABA(ARs and, in high concentrations (10 mM, as negative modulator of the strychnine-sensitive glycine receptor. However, the exact molecular mechanisms by which histamine acts on GABA(ARs are unknown. In our study, we aimed to identify amino acids potentially involved in the modulatory effect of histamine on GABA(ARs. We expressed GABA(ARs with 12 different point mutations in Xenopus laevis oocytes and characterized the effect of histamine on GABA-induced currents using the two-electrode voltage clamp technique. Our data demonstrate that the amino acid residues ß2(N265 and ß2(M286, which are important for modulation by propofol, are not involved in the action of histamine. However, we found that histamine modulation is dependent on the amino acid residues alpha1(R120, ß2(Y157, ß3(D163, ß3(V175 and ß3(Q185. We showed that the amino acid residues ß2(Y157 and ß3(Q185 mediate the positive modulatory effect of histamine on GABA-induced currents, whereas alpha1(R120 and ß2(D163 form a potential histamine interaction site in GABA(ARs.

XMRV: usage of receptors and potential co-receptors

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Gaddam Durga

2011-09-01

Full Text Available Abstract Background XMRV is a gammaretrovirus first identified in prostate tissues of Prostate Cancer (PC patients and later in the blood cells of patients with Chronic Fatigue Syndrome (CFS. Although XMRV is thought to use XPR1 for cell entry, it infects A549 cells that do not express XPR1, suggesting usage of other receptors or co-receptors. Methods To study the usage of different receptors and co- receptors that could play a role in XMRV infection of lymphoid cells and GHOST (GFP- Human osteosarcoma cells expressing CD4 along with different chemokine receptors including CCR1, CCR2, etc., were infected with XMRV. Culture supernatants and cells were tested for XMRV replication using real time quantitative PCR. Results Infection and replication of XMRV was seen in a variety of GHOST cells, LNCaP, DU145, A549 and Caski cell lines. The levels of XMRV replication varied in different cell lines showing differential replication in different cell lines. However, replication in A549 which lacks XPR1 expression was relatively higher than DU145 but lower than, LNCaP. XMRV replication varied in GHOST cell lines expressing CD4 and each of the co- receptors CCR1-CCR8 and bob. There was significant replication of XMRV in CCR3 and Bonzo although it is much lower when compared to DU145, A549 and LNCaP. Conclusion XMRV replication was observed in GHOST cells that express CD4 and each of the chemokine receptors ranging from CCR1- CCR8 and BOB suggesting that infectivity in hematopoietic cells could be mediated by use of these receptors.

GABA receptor imaging

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Lee, Jong Doo [Yonsei University College of Medicine, Seoul (Korea, Republic of)

2007-04-15

GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, GABA{sub A}-receptor that allows chloride to pass through a ligand gated ion channel and GABA{sub B}-receptor that uses G-proteins for signaling. The GABA{sub A}-receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate GABA{sub A}-receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with {sup 11}C-FMZ, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, {sup 18}F-fluoroflumazenil (FFMZ) has been developed to overcome {sup 11}C's short half-life. {sup 18}F-FFMZ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using '1{sup 1}C-FMZ PET instead of {sup 18}F-FDG, PET, restrict the foci better and may also help find lesions better than high resolution MR. GABA{sub A} receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, GABA imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas.

GABA receptor imaging

International Nuclear Information System (INIS)

Lee, Jong Doo

2007-01-01

GABA is primary an inhibitory neurotransmitter that is localized in inhibitory interneurons. GABA is released from presynaptic terminals and functions by binding to GABA receptors. There are two types of GABA receptors, GABA A -receptor that allows chloride to pass through a ligand gated ion channel and GABA B -receptor that uses G-proteins for signaling. The GABA A -receptor has a GABA binding site as well as a benzodiazepine binding sites, which modulate GABA A -receptor function. Benzodiazepine GABAA receptor imaging can be accomplished by radiolabeling derivates that activates benzodiazepine binding sites. There has been much research on flumazenil (FMZ) labeled with 11 C-FMZ, a benzodiazepine derivate that is a selective, reversible antagonist to GABAA receptors. Recently, 18 F-fluoroflumazenil (FFMZ) has been developed to overcome 11 C's short half-life. 18 F-FFMZ shows high selective affinity and good pharmacodynamics, and is a promising PET agent with better central benzodiazepine receptor imaging capabilities. In an epileptic focus, because the GABA/benzodiazepine receptor amount is decreased, using '1 1 C-FMZ PET instead of 18 F-FDG, PET, restrict the foci better and may also help find lesions better than high resolution MR. GABA A receptors are widely distributed in the cerebral cortex, and can be used as an viable neuronal marker. Therefore it can be used as a neuronal cell viability marker in cerebral ischemia. Also, GABA-receptors decrease in areas where neuronal plasticity develops, therefore, GABA imaging can be used to evaluate plasticity. Besides these usages, GABA receptors are related with psychological diseases, especially depression and schizophrenia as well as cerebral palsy, a motor-related disorder, so further in-depth studies are needed for these areas

Autoantibodies Targeting AT1 Receptor from Patients with Acute Coronary Syndrome Upregulate Proinflammatory Cytokines Expression in Endothelial Cells Involving NF-κB Pathway

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Weijuan Li

2014-01-01

Full Text Available Our study intended to prove whether agonistic autoantibodies to angiotensin II type 1 receptor (AT1-AAs exist in patients with coronary heart disease (CHD and affect the human endothelial cell (HEC by upregulating proinflammatory cytokines expression involved in NF-κB pathway. Antibodies were determined by chronotropic responses of cultured neonatal rat cardiomyocytes coupled with receptor-specific antagonists (valsartan and AT1-EC2 as described previously. Interleukin-6 (IL-6, vascular cell adhesion molecule-1 (VCAM-1, and monocyte chemotactic protein-1 (MCP-1 expression were improved at both mRNA and protein levels in HEC, while NF-κB in the DNA level was improved detected by electrophoretic mobility shift assays (EMSA. These improvements could be inhibited by specific AT1 receptor blocker valsartan, NF-κB blocker pyrrolidine dithiocarbamate (PDTC, and specific short peptides from the second extracellular loop of AT1 receptor. These results suggested that AT1-AAs, via the AT1 receptor, induce expression of proinflammatory cytokines involved in the activation of NF-κB. AT1-AAs may play a great role in the pathogenesis of the acute coronary syndrome by mediating vascular inflammatory effects involved in the NF-κB pathway.

Stage-specific sampling by pattern recognition receptors during Candida albicans phagocytosis.

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Sigrid E M Heinsbroek

2008-11-01

Full Text Available Candida albicans is a medically important pathogen, and recognition by innate immune cells is critical for its clearance. Although a number of pattern recognition receptors have been shown to be involved in recognition and phagocytosis of this fungus, the relative role of these receptors has not been formally examined. In this paper, we have investigated the contribution of the mannose receptor, Dectin-1, and complement receptor 3; and we have demonstrated that Dectin-1 is the main non-opsonic receptor involved in fungal uptake. However, both Dectin-1 and complement receptor 3 were found to accumulate at the site of uptake, while mannose receptor accumulated on C. albicans phagosomes at later stages. These results suggest a potential role for MR in phagosome sampling; and, accordingly, MR deficiency led to a reduction in TNF-alpha and MCP-1 production in response to C. albicans uptake. Our data suggest that pattern recognition receptors sample the fungal phagosome in a sequential fashion.

Differential modulation of Beta-adrenergic receptor signaling by trace amine-associated receptor 1 agonists.

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Gunnar Kleinau

Full Text Available Trace amine-associated receptors (TAAR are rhodopsin-like G-protein-coupled receptors (GPCR. TAAR are involved in modulation of neuronal, cardiac and vascular functions and they are potentially linked with neurological disorders like schizophrenia and Parkinson's disease. Subtype TAAR1, the best characterized TAAR so far, is promiscuous for a wide set of ligands and is activated by trace amines tyramine (TYR, phenylethylamine (PEA, octopamine (OA, but also by thyronamines, dopamine, and psycho-active drugs. Unfortunately, effects of trace amines on signaling of the two homologous β-adrenergic receptors 1 (ADRB1 and 2 (ADRB2 have not been clarified yet in detail. We, therefore, tested TAAR1 agonists TYR, PEA and OA regarding their effects on ADRB1/2 signaling by co-stimulation studies. Surprisingly, trace amines TYR and PEA are partial allosteric antagonists at ADRB1/2, whereas OA is a partial orthosteric ADRB2-antagonist and ADRB1-agonist. To specify molecular reasons for TAAR1 ligand promiscuity and for observed differences in signaling effects on particular aminergic receptors we compared TAAR, tyramine (TAR octopamine (OAR, ADRB1/2 and dopamine receptors at the structural level. We found especially for TAAR1 that the remarkable ligand promiscuity is likely based on high amino acid similarity in the ligand-binding region compared with further aminergic receptors. On the other hand few TAAR specific properties in the ligand-binding site might determine differences in ligand-induced effects compared to ADRB1/2. Taken together, this study points to molecular details of TAAR1-ligand promiscuity and identified specific trace amines as allosteric or orthosteric ligands of particular β-adrenergic receptor subtypes.

Characterization of Angiotensin II Molecular Determinants Involved in AT1 Receptor Functional Selectivity.

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Domazet, Ivana; Holleran, Brian J; Richard, Alexandra; Vandenberghe, Camille; Lavigne, Pierre; Escher, Emanuel; Leduc, Richard; Guillemette, Gaétan

2015-06-01

The octapeptide angiotensin II (AngII) exerts a variety of cardiovascular effects through the activation of the AngII type 1 receptor (AT1), a G protein-coupled receptor. The AT1 receptor engages and activates several signaling pathways, including heterotrimeric G proteins Gq and G12, as well as the extracellular signal-regulated kinases (ERK) 1/2 pathway. Additionally, following stimulation, βarrestin is recruited to the AT1 receptor, leading to receptor desensitization. It is increasingly recognized that specific ligands selectively bind and favor the activation of some signaling pathways over others, a concept termed ligand bias or functional selectivity. A better understanding of the molecular basis of functional selectivity may lead to the development of better therapeutics with fewer adverse effects. In the present study, we developed assays allowing the measurement of six different signaling modalities of the AT1 receptor. Using a series of AngII peptide analogs that were modified in positions 1, 4, and 8, we sought to better characterize the molecular determinants of AngII that underlie functional selectivity of the AT1 receptor in human embryonic kidney 293 cells. The results reveal that position 1 of AngII does not confer functional selectivity, whereas position 4 confers a bias toward ERK signaling over Gq signaling, and position 8 confers a bias toward βarrestin recruitment over ERK activation and Gq signaling. Interestingly, the analogs modified in position 8 were also partial agonists of the protein kinase C (PKC)-dependent ERK pathway via atypical PKC isoforms PKCζ and PKCι. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

The two-state dimer receptor model: a general model for receptor dimers.

Science.gov (United States)

Franco, Rafael; Casadó, Vicent; Mallol, Josefa; Ferrada, Carla; Ferré, Sergi; Fuxe, Kjell; Cortés, Antoni; Ciruela, Francisco; Lluis, Carmen; Canela, Enric I

2006-06-01

Nonlinear Scatchard plots are often found for agonist binding to G-protein-coupled receptors. Because there is clear evidence of receptor dimerization, these nonlinear Scatchard plots can reflect cooperativity on agonist binding to the two binding sites in the dimer. According to this, the "two-state dimer receptor model" has been recently derived. In this article, the performance of the model has been analyzed in fitting data of agonist binding to A(1) adenosine receptors, which are an example of receptor displaying concave downward Scatchard plots. Analysis of agonist/antagonist competition data for dopamine D(1) receptors using the two-state dimer receptor model has also been performed. Although fitting to the two-state dimer receptor model was similar to the fitting to the "two-independent-site receptor model", the former is simpler, and a discrimination test selects the two-state dimer receptor model as the best. This model was also very robust in fitting data of estrogen binding to the estrogen receptor, for which Scatchard plots are concave upward. On the one hand, the model would predict the already demonstrated existence of estrogen receptor dimers. On the other hand, the model would predict that concave upward Scatchard plots reflect positive cooperativity, which can be neither predicted nor explained by assuming the existence of two different affinity states. In summary, the two-state dimer receptor model is good for fitting data of binding to dimeric receptors displaying either linear, concave upward, or concave downward Scatchard plots.

Localization of mineralocorticoid receptors at mammalian synapses.

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Eric M Prager

Full Text Available In the brain, membrane associated nongenomic steroid receptors can induce fast-acting responses to ion conductance and second messenger systems of neurons. Emerging data suggest that membrane associated glucocorticoid and mineralocorticoid receptors may directly regulate synaptic excitability during times of stress when adrenal hormones are elevated. As the key neuron signaling interface, the synapse is involved in learning and memory, including traumatic memories during times of stress. The lateral amygdala is a key site for synaptic plasticity underlying conditioned fear, which can both trigger and be coincident with the stress response. A large body of electrophysiological data shows rapid regulation of neuronal excitability by steroid hormone receptors. Despite the importance of these receptors, to date, only the glucocorticoid receptor has been anatomically localized to the membrane. We investigated the subcellular sites of mineralocorticoid receptors in the lateral amygdala of the Sprague-Dawley rat. Immunoblot analysis revealed the presence of mineralocorticoid receptors in the amygdala. Using electron microscopy, we found mineralocorticoid receptors expressed at both nuclear including: glutamatergic and GABAergic neurons and extra nuclear sites including: presynaptic terminals, neuronal dendrites, and dendritic spines. Importantly we also observed mineralocorticoid receptors at postsynaptic membrane densities of excitatory synapses. These data provide direct anatomical evidence supporting the concept that, at some synapses, synaptic transmission is regulated by mineralocorticoid receptors. Thus part of the stress signaling response in the brain is a direct modulation of the synapse itself by adrenal steroids.

Testosterone-Dependent Interaction between Androgen Receptor and Aryl Hydrocarbon Receptor Induces Liver Receptor Homolog 1 Expression in Rat Granulosa Cells

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Wu, Yanguang; Baumgarten, Sarah C.; Zhou, Ping

2013-01-01

Androgens play a major role in the regulation of normal ovarian function; however, they are also involved in the development of ovarian pathologies. These contrasting effects may involve a differential response of granulosa cells to the androgens testosterone (T) and dihydrotestosterone (DHT). To determine the molecular pathways that mediate the distinct effects of T and DHT, we studied the expression of the liver receptor homolog 1 (LRH-1) gene, which is differentially regulated by these steroids. We found that although both T and DHT stimulate androgen receptor (AR) binding to the LRH-1 promoter, DHT prevents T-mediated stimulation of LRH-1 expression. T stimulated the expression of aryl hydrocarbon receptor (AHR) and its interaction with the AR. T also promoted the recruitment of the AR/AHR complex to the LRH-1 promoter. These effects were not mimicked by DHT. We also observed that the activation of extracellular regulated kinases by T is required for AR and AHR interaction. In summary, T, but not DHT, stimulates AHR expression and the interaction between AHR and AR, leading to the stimulation of LRH-1 expression. These findings could explain the distinct response of granulosa cells to T and DHT and provide a molecular mechanism by which DHT negatively affects ovarian function. PMID:23689136

The Role of Adenosine Receptors in Psychostimulant Addiction

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Inmaculada Ballesteros-Yáñez

2018-01-01

Full Text Available Adenosine receptors (AR are a family of G-protein coupled receptors, comprised of four members, named A1, A2A, A2B, and A3 receptors, found widely distributed in almost all human body tissues and organs. To date, they are known to participate in a large variety of physiopathological responses, which include vasodilation, pain, and inflammation. In particular, in the central nervous system (CNS, adenosine acts as a neuromodulator, exerting different functions depending on the type of AR and consequent cellular signaling involved. In terms of molecular pathways and second messengers involved, A1 and A3 receptors inhibit adenylyl cyclase (AC, through Gi/o proteins, while A2A and A2B receptors stimulate it through Gs proteins. In the CNS, A1 receptors are widely distributed in the cortex, hippocampus, and cerebellum, A2A receptors are localized mainly in the striatum and olfactory bulb, while A2B and A3 receptors are found at low levels of expression. In addition, AR are able to form heteromers, both among themselves (e.g., A1/A2A, as well as with other subtypes (e.g., A2A/D2, opening a whole range of possibilities in the field of the pharmacology of AR. Nowadays, we know that adenosine, by acting on adenosine A1 and A2A receptors, is known to antagonistically modulate dopaminergic neurotransmission and therefore reward systems, being A1 receptors colocalized in heteromeric complexes with D1 receptors, and A2A receptors with D2 receptors. This review documents the present state of knowledge of the contribution of AR, particularly A1 and A2A, to psychostimulants-mediated effects, including locomotor activity, discrimination, seeking and reward, and discuss their therapeutic relevance to psychostimulant addiction. Studies presented in this review reinforce the potential of A1 agonists as an effective strategy to counteract psychostimulant-induced effects. Furthermore, different experimental data support the hypothesis that A2A/D2 heterodimers are

Allelic association of the D2 dopamine receptor gene with receptor-binding characteristics in alcoholism

International Nuclear Information System (INIS)

Noble, E.P.; Blum, K.; Ritchie, T.; Montgomery, A.; Sheridan, P.J.

1991-01-01

The allelic association of the human D2 dopamine receptor gene with the binding characteristics of the D2 dopamine receptor was determined in 66 brains of alcoholic and non-alcoholic subjects. In a blinded experiment, DNA from the cerebral cortex was treated with the restriction endonuclease Taql and probed with a 1.5-kilobase (kb) digest of a clone (lambda hD2G1) of the human D2 dopamine receptor gene. The binding characteristics (Kd [binding affinity] and Bmax [number of binding sites]) of the D2 dopamine receptor were determined in the caudate nuclei of these brains using tritiated spiperone as the ligand. The adjusted Kd was significantly lower in alcoholic than in nonalcoholic subjects. In subjects with the A1 allele, in whom a high association with alcoholism was found, the Bmax was significantly reduced compared with the Bmax of subjects with the A2 allele. Moreover, a progressively reduced Bmax was found in subjects with A2/A2, A1/A2, and A1/A1 alleles, with subjects with A2/A2 having the highest mean values, and subjects with A1/A1, the lowest. The polymorphic pattern of the D2 dopamine receptor gene and its differential expression of receptors suggests the involvement of the dopaminergic system in conferring susceptibility to at least one subtype of severe alcoholism

Xenobiotics and the Glucocorticoid Receptor

International Nuclear Information System (INIS)

Gulliver, Linda S M

2017-01-01

Receptor. • Involvement of Glucocorticoid Receptor in multiple pathologies. • Novel xenobiotic ligands for Glucocorticoid Receptor. • Potential for multifaceted Glucocorticoid Receptor-targeted pharmacological interventions.

Xenobiotics and the Glucocorticoid Receptor

Energy Technology Data Exchange (ETDEWEB)

Gulliver, Linda S M, E-mail: linda.gulliver@otago.ac.nz

2017-03-15

Receptor. • Involvement of Glucocorticoid Receptor in multiple pathologies. • Novel xenobiotic ligands for Glucocorticoid Receptor. • Potential for multifaceted Glucocorticoid Receptor-targeted pharmacological interventions.

Signal transduction through the IL-4 and insulin receptor families.

Science.gov (United States)

Wang, L M; Keegan, A; Frankel, M; Paul, W E; Pierce, J H

1995-07-01

Activation of tyrosine kinase-containing receptors and intracellular tyrosine kinases by ligand stimulation is known to be crucial for mediating initial and subsequent events involved in mitogenic signal transduction. Receptors for insulin and insulin-like growth factor 1 (IGF-1) contain cytoplasmic tyrosine kinase domains that undergo autophosphorylation upon ligand stimulation. Activation of these receptors also leads to pronounced and rapid tyrosine phosphorylation of insulin receptor substrate 1 (IRS-1) in cells of connective tissue origin. A related substrate, designated 4PS, is similarly phosphorylated by insulin and IGF-1 stimulation in many hematopoietic cell types. IRS-1 and 4PS possess a number of tyrosine phosphorylation sites that are within motifs that bind specific SH2-containing molecules known to be involved in mitogenic signaling such as PI-3 kinase, SHPTP-2 (Syp) and Grb-2. Thus, they appear to act as docking substrates for a variety of signaling molecules. The majority of hematopoietic cytokines bind to receptors that do not possess intrinsic kinase activity, and these receptors have been collectively termed as members of the hematopoietin receptor superfamily. Despite their lack of tyrosine kinase domains, stimulation of these receptors has been demonstrated to activate intracellular kinases leading to tyrosine phosphorylation of multiple substrates. Recent evidence has demonstrated that activation of different members of the Janus family of tyrosine kinases is involved in mediating tyrosine phosphorylation events by specific cytokines. Stimulation of the interleukin 4 (IL-4) receptor, a member of the hematopoietin receptor superfamily, is thought to result in activation of Jak1, Jak3, and/or Fes tyrosine kinases.(ABSTRACT TRUNCATED AT 250 WORDS)

Nociceptin and the nociceptin receptor in learning and memory

OpenAIRE

Andero, Raül

2015-01-01

There are many processes in which the neuropeptide nociceptin/orphanin FQ (N/OFQ or nociceptin) is involved in the brain. The role of nociceptin in learning and memory holds promise in modulating these processes in health and disease in the human brain. This review summarizes the body of research focused on N/OFQ and its specific receptor, the nociceptin receptor (NOP receptor), in learning and memory, and its potential mechanisms of action, in which acetylcholine, NMDA receptor and noradrena...

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

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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

[The receptor theory of atherosclerosis].

Science.gov (United States)

Likhoded, V G; Bondarenko, V M; Gintsburg, A L

2010-01-01

Lipopolysaccharides of Gram-negative bacteria can interact with Toll-like receptor 4 (TLR4) and induce atheroma formation. The risk of atherosclerosis is decreased in case of TLR4 mutation. Other bacterial ligands and endogenous ligands of TLRs can also be involved in induction of atherogenesis. The general concept of atherosclerosis pathogentsis is presented. According to this concept atherogenesis can be initiated by some reactions resulting from interaction of exogenous and endogenous microbial ligands with Toll-like receptors.

Reduced post-synaptic serotonin type 1A receptor binding in bipolar depression

Science.gov (United States)

Nugent, Allison C.; Bain, Earle E.; Carlson, Paul J.; Neumeister, Alexander; Bonne, Omer; Carson, Richard E.; Eckelman, William; Herscovitch, Peter; Zarate, Carlos A.; Charney, Dennis S.; Drevets, Wayne C.

2013-01-01

Multiple lines of evidence suggest that serotonin type 1A (5-HT1A) receptor dysfunction is involved in the pathophysiology of mood disorders, and that alterations in 5-HT1A receptor function play a role in the mechanisms of antidepressant and mood stabilizer treatment. The literature is in disagreement, however, as to whether 5-HT1A receptor binding abnormalities exist in bipolar disorder (BD). We acquired PET images of 5-HT1A receptor binding in 26 unmedicated BD subjects and 37 healthy controls using [18F]FCWAY, a highly selective 5-HT1A receptor radio-ligand. The mean 5-HT1A receptor binding potential (BPP) was significantly lower in BD subjects compared to controls in cortical regions where 5-HT1A receptors are expressed post-synaptically, most prominently in the mesiotemporal cortex. Post-hoc assessments involving other receptor specific binding parameters suggested that this difference particularly affected the females with BD. The mean BPP did not differ between groups in the raphe nucleus, however, where 5-HT1A receptors are predominantly expressed pre-synaptically. Across subjects the BPP in the mesiotemporal cortex was inversely correlated with trough plasma cortisol levels, consistent with preclinical literature indicating that hippocampal 5-HT1A receptor expression is inhibited by glucocorticoid receptor stimulation. These findings suggest that 5-HT1A receptor binding is abnormally reduced in BD, and this abnormality may particularly involve the postsynaptic 5-HT1A receptor system of individuals with a tendency toward cortisol hypersecretion. PMID:23434290

ARF6 and GASP-1 are post-endocytic sorting proteins selectively involved in the intracellular trafficking of dopamine D2 receptors mediated by GRK and PKC in transfected cells

Science.gov (United States)

Cho, DI; Zheng, M; Min, C; Kwon, KJ; Shin, CY; Choi, HK; Kim, KM

2013-01-01

Background and Purpose GPCRs undergo both homologous and heterologous regulatory processes in which receptor phosphorylation plays a critical role. The protein kinases responsible for each pathway are well established; however, other molecular details that characterize each pathway remain unclear. In this study, the molecular mechanisms that determine the differences in the functional roles and intracellular trafficking between homologous and PKC-mediated heterologous internalization pathways for the dopamine D2 receptor were investigated. Experimental Approach All of the S/T residues located within the intracellular loops of D2 receptor were mutated, and the residues responsible for GRK- and PKC-mediated internalization were determined in HEK-293 cells and SH-SY5Y cells. The functional role of receptor internalization and the cellular components that determine the post-endocytic fate of internalized D2 receptors were investigated in the transfected cells. Key Results T134, T225/S228/S229 and S325 were involved in PKC-mediated D2 receptor desensitization. S229 and adjacent S/T residues mediated the PKC-dependent internalization of D2 receptors, which induced down-regulation and desensitization. S/T residues within the second intracellular loop and T225 were the major residues involved in GRK-mediated internalization of D2 receptors, which induced receptor resensitization. ARF6 mediated the recycling of D2 receptors internalized in response to agonist stimulation. In contrast, GASP-1 mediated the down-regulation of D2 receptors internalized in a PKC-dependent manner. Conclusions and Implications GRK- and PKC-mediated internalizations of D2 receptors occur through different intracellular trafficking pathways and mediate distinct functional roles. Distinct S/T residues within D2 receptors and different sorting proteins are involved in the dissimilar regulation of D2 receptors by GRK2 and PKC. PMID:23082996

The effects of the alpha2-adrenergic receptor agonists clonidine and rilmenidine, and antagonists yohimbine and efaroxan, on the spinal cholinergic receptor system in the rat

DEFF Research Database (Denmark)

Abelson, Klas S P; Höglund, A Urban

2004-01-01

Cholinergic agonists produce spinal antinociception via mechanisms involving an increased release of intraspinal acetylcholine. The cholinergic receptor system interacts with several other receptor types, such as alpha2-adrenergic receptors. To fully understand these interactions, the effects...... of various receptor ligands on the cholinergic system must be investigated in detail. This study was initiated to investigate the effects of the alpha2-adrenergic receptor agonists clonidine and rilmenidine and the alpha2-adrenergic receptor antagonists yohimbine and efaroxan on spinal cholinergic receptors......, all ligands possessed affinity for nicotinic receptors. Clonidine and yohimbine binding was best fit to a one site binding curve and rilmenidine and efaroxan to a two site binding curve. The present study demonstrates that the tested alpha2-adrenergic receptor ligands affect intraspinal acetylcholine...

Mode of Action and Human Relevance Analysis for Nuclear Receptor-Mediated Liver Toxicity: A Case Study with Phenobarbital as a Model Constitutive Androstane Receptor (CAR) Activator

Science.gov (United States)

The constitutive androstane receptor (CAR) and pregnane X receptor (PXR) are key nuclear receptors involved in the regulation of cellular responses. to exposure to many xenobiotics and various physiological processes. Phenobarbital (PB) is a non­ genotoxic i...

Small molecule antagonists of integrin receptors.

Science.gov (United States)

Perdih, A; Dolenc, M Sollner

2010-01-01

The complex and widespread family of integrin receptors is involved in numerous physiological processes, such as tissue remodeling, angiogenesis, development of the immune response and homeostasis. In addition, their key role has been elucidated in important pathological disorders such as cancer, cardiovascular diseases, osteoporosis, autoimmune and inflammatory diseases and in the pathogenesis of infectious diseases, making them highly important targets for modern drug design campaigns. In this review we seek to present a concise overview of the small molecule antagonists of this diverse and highly complex receptor family. Integrin antagonists are classified according to the targeted integrin receptor and are discussed in four sections. First we present the fibrinogen alpha(IIb)beta3 and the vitronectin alpha (V)beta(3) receptor antagonists. The remaining selective integrin antagonists are examined in the third section. The final section is dedicated to molecules with dual or multiple integrin activity. In addition, the use of antibodies and peptidomimetic approaches to modulate the integrin receptors are discussed, as well providing the reader with an overall appreciation of the field.

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...

Channel opening of γ-aminobutyric acid receptor from rat brain: molecular mechanisms of the receptor responses

International Nuclear Information System (INIS)

Cash, D.J.; Subbarao, K.

1987-01-01

The function of γ-aminobutyric acid (GABA) receptors, which mediate transmembrane chloride flux, can be studied by use of 36 Cl - isotope tracer with membrane from mammalian brain by quench-flow technique, with reaction times that allow resolution of the receptor desensitization rates from the ion flux rates. The rates of chloride exchange into the vesicles in the absence and presence of GABA were characterized with membrane from rat cerebral cortex. Unspecific 36 Cl - influx was completed in three phases of ca. 3% (t/sub 1/2/ = 0.6 s), 56% (t/sub 1/2 = 82 s), and 41% (t/sub 1/2 = 23 min). GABA-mediated, specific chloride exchange occurred with 6.5% of the total vesicular internal volume. The GABA-dependent 36 Cl - influx proceeded in two phases, each progressively slowed by desensitization. The measurements supported the presence of two distinguishable active GABA receptors on the same membrane mediating chloride exchange into the vesicles. The half-response concentrations were similar for both receptors. The two receptors were present in the activity ratio of ca. 4/1, similar to the ratio of low affinity to high-affinity GABA sites found in ligand binding experiments. The desensitization rates have a different dependence on GABA concentration than the channel-opening equilibria. For both receptors, the measurements over a 2000-fold GABA concentration range required a minimal mechanism involving the occupation of both of the two GABA binding sites for significant channel opening; then the receptors were ca. 80% open. Similarly for both receptors, desensitization was mediated by a different pair of binding sites, although desensitization with only one ligand molecule bound could occur at a 20-fold slower rate

Serotonergic Regulation of Prefrontal Cortical Circuitries Involved in Cognitive Processing: A Review of Individual 5-HT Receptor Mechanisms and Concerted Effects of 5-HT Receptors Exemplified by the Multimodal Antidepressant Vortioxetine.

Science.gov (United States)

Leiser, Steven C; Li, Yan; Pehrson, Alan L; Dale, Elena; Smagin, Gennady; Sanchez, Connie

2015-07-15

It has been known for several decades that serotonergic neurotransmission is a key regulator of cognitive function, mood, and sleep. Yet with the relatively recent discoveries of novel serotonin (5-HT) receptor subtypes, as well as an expanding knowledge of their expression level in certain brain regions and localization on certain cell types, their involvement in cognitive processes is still emerging. Of particular interest are cognitive processes impacted in neuropsychiatric and neurodegenerative disorders. The prefrontal cortex (PFC) is critical to normal cognitive processes, including attention, impulsivity, planning, decision-making, working memory, and learning or recall of learned memories. Furthermore, serotonergic dysregulation within the PFC is implicated in many neuropsychiatric disorders associated with prominent symptoms of cognitive dysfunction. Thus, it is important to better understand the overall makeup of serotonergic receptors in the PFC and on which cell types these receptors mediate their actions. In this Review, we focus on 5-HT receptor expression patterns within the PFC and how they influence cognitive behavior and neurotransmission. We further discuss the net effects of vortioxetine, an antidepressant acting through multiple serotonergic targets given the recent findings that vortioxetine improves cognition by modulating multiple neurotransmitter systems.

Protection against MDMA-induced dopaminergic neurotoxicity in mice by methyllycaconitine: involvement of nicotinic receptors.

Science.gov (United States)

Chipana, C; Camarasa, J; Pubill, D; Escubedo, E

2006-09-01

Methylenedioxymethamphetamine (MDMA) is a relatively selective dopaminergic neurotoxin in mice. Previous studies demonstrated the participation of alpha-7 nicotinic receptors (nAChR) in the neurotoxic effect of methamphetamine. The aim of this paper was to study the role of this receptor type in the acute effects and neurotoxicity of MDMA in mice. In vivo, methyllycaconitine (MLA), a specific alpha-7 nAChR antagonist, significantly prevented MDMA-induced neurotoxicity at dopaminergic but not at serotonergic level, without affecting MDMA-induced hyperthermia. Glial activation was also fully prevented by MLA. In vitro, MDMA induced intrasynaptosomal reactive oxygen species (ROS) generation, which was calcium-, nitric-oxide synthase-, and protein kinase C-dependent. Also, the increase in ROS was prevented by MLA and alpha-bungarotoxin. Experiments with reserpine point to endogenous dopamine (DA) as the main source of MDMA-induced ROS. MLA also brought the MDMA-induced inhibition of [3H]DA uptake down, from 73% to 11%. We demonstrate that a coordinated activation of alpha-7 nAChR, blockade of DA transporter function and displacement of DA from intracellular stores induced by MDMA produces a neurotoxic effect that can be prevented by MLA, suggesting that alpha-7 nAChR have a key role in the MDMA neurotoxicity in mice; however, the involvement of nicotinic receptors containing the beta2 subunit cannot be conclusively ruled out.

An unusual protein kinase phosphorylates the chemotactic receptor of Dictystelium discoideum

International Nuclear Information System (INIS)

Meier, K.; Klein, C.

1988-01-01

The authors report the cAMP-dependent phosphorylation of the chemotactic receptor of Dictyostelium discoideum in partially purified plasma membranes. The protein kinase responsible for receptor phosphorylation is associated with this fraction and preferentially phosphorylates the ligand-occupied form of the receptor. 8-Azido[ 32 P]cAMP labeling of the cell surface has shown that the cAMP receptor exists in two forms. A 45-kDa protein is predominant on unstimulated cells. cAMP stimulation results in an increased receptor phosphorylation such that the receptor migrates on NaDodSO 4 /PAGE as a 47-kDa protein. Phosphorylation of the chemotactic receptor is not detected in membrane preparations unless cAMP is added to the incubation mixture. Only under those conditions is the phosphorylated 47-kDa form observed. The requirement for cAMP reflects the fact that the kinase involved preferentially uses the ligand-occupied receptor as a substrate. In vitro phosphorylation of the receptor does not involve tyrosine residues. The enzyme does not appear to be a cAMP- or cGMP-dependent protein kinase nor is it sensitive to guanine nucleotides, Ca 2+ /calmodulin, Ca 2+ /phospholipid, or EGTA. Similarities with the β-adrenergic receptor protein kinase are discussed

Lipoprotein receptors in cultured bovine endothelial cells

International Nuclear Information System (INIS)

Struempfer, A.E.M.

1983-07-01

In this study, receptors that may be involved in the uptake of low density lipoproteins (LDL) and low density lipoproteins which have been modified by acetylation (AcLDL), were characterized. Aortic epithelial cells were used and a cell culture system which closely resembled the in vivo monolayer was established. Endothelial cell and lipoprotein interactions were examined by incubating the cells with 125 l-labelled lipoproteins under various conditions. The receptor affinity of bovine aortic endothelial cells was higher for AcLDL than that for LDL. Competition studies demonstrated that there were two distinct receptors for LDL and AcLDL on the endothelial cells. AcLDL did not compete with LDL for the LDL receptor, and conversely LDL did not compete with AcLDL for the AcLDL receptor. The receptor activities for LDL and AcLDL were examined as a function of culture age. Whereas the LDL receptor could be regulated, the AcLDL receptor was not as susceptible to regulation. Upon exposing endothelial cells for 72 h to either LDL or AcLDL, it was found that the total amount of cellular cholesterol increased by about 50%. However, the increase of total cholesterol was largely in the form of free cholesterol. This is in contrast to macrophages, where the increase in total cholesterol upon exposure to AcLDL is largely in the form cholesteryl esters

Nuclear receptors and nonalcoholic fatty liver disease1

Science.gov (United States)

Cave, Matthew C.; Clair, Heather B.; Hardesty, Josiah E.; Falkner, K. Cameron; Feng, Wenke; Clark, Barbara J.; Sidey, Jennifer; Shi, Hongxue; Aqel, Bashar A.; McClain, Craig J.; Prough, Russell A.

2016-01-01

Nuclear receptors are transcription factors which sense changing environmental or hormonal signals and effect transcriptional changes to regulate core life functions including growth, development, and reproduction. To support this function, following ligand-activation by xenobiotics, members of subfamily 1 nuclear receptors (NR1s) may heterodimerize with the retinoid X receptor (RXR) to regulate transcription of genes involved in energy and xenobiotic metabolism and inflammation. Several of these receptors including the peroxisome proliferator-activated receptors (PPARs), the pregnane and xenobiotic receptor (PXR), the constitutive androstane receptor (CAR), the liver X receptor (LXR) and the farnesoid X receptor (FXR) are key regulators of the gut:liver:adipose axis and serve to coordinate metabolic responses across organ systems between the fed and fasting states. Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease and may progress to cirrhosis and even hepatocellular carcinoma. NAFLD is associated with inappropriate nuclear receptor function and perturbations along the gut:liver:adipose axis including obesity, increased intestinal permeability with systemic inflammation, abnormal hepatic lipid metabolism, and insulin resistance. Environmental chemicals may compound the problem by directly interacting with nuclear receptors leading to metabolic confusion and the inability to differentiate fed from fasting conditions. This review focuses on the impact of nuclear receptors in the pathogenesis and treatment of NAFLD. Clinical trials including PIVENS and FLINT demonstrate that nuclear receptor targeted therapies may lead to the paradoxical dissociation of steatosis, inflammation, fibrosis, insulin resistance, dyslipidemia and obesity. Novel strategies currently under development (including tissue-specific ligands and dual receptor agonists) may be required to separate the beneficial effects of nuclear receptor activation from unwanted metabolic

Gβ promotes pheromone receptor polarization and yeast chemotropism by inhibiting receptor phosphorylation.

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Ismael, Amber; Tian, Wei; Waszczak, Nicholas; Wang, Xin; Cao, Youfang; Suchkov, Dmitry; Bar, Eli; Metodiev, Metodi V; Liang, Jie; Arkowitz, Robert A; Stone, David E

2016-04-12

Gradient-directed cell migration (chemotaxis) and growth (chemotropism) are processes that are essential to the development and life cycles of all species. Cells use surface receptors to sense the shallow chemical gradients that elicit chemotaxis and chemotropism. Slight asymmetries in receptor activation are amplified by downstream signaling systems, which ultimately induce dynamic reorganization of the cytoskeleton. During the mating response of budding yeast, a model chemotropic system, the pheromone receptors on the plasma membrane polarize to the side of the cell closest to the stimulus. Although receptor polarization occurs before and independently of actin cable-dependent delivery of vesicles to the plasma membrane (directed secretion), it requires receptor internalization. Phosphorylation of pheromone receptors by yeast casein kinase 1 or 2 (Yck1/2) stimulates their internalization. We showed that the pheromone-responsive Gβγ dimer promotes the polarization of the pheromone receptor by interacting with Yck1/2 and locally inhibiting receptor phosphorylation. We also found that receptor phosphorylation is essential for chemotropism, independently of its role in inducing receptor internalization. A mathematical model supports the idea that the interaction between Gβγ and Yck1/2 results in differential phosphorylation and internalization of the pheromone receptor and accounts for its polarization before the initiation of directed secretion. Copyright © 2016, American Association for the Advancement of Science.

Differential ontogenetic patterns of levocabastine-sensitive neurotensin NT2 receptors and of NT1 receptors in the rat brain revealed by in situ hybridization.

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Lépée-Lorgeoux, I; Betancur, C; Rostène, W; Pélaprat, D

1999-03-12

The postnatal ontogeny of the levocabastine-sensitive neurotensin receptor (NT2) mRNA was studied by in situ hybridization in the rat brain and compared with the distribution of the levocabastine-insensitive NT1 receptor. NT2 receptor mRNA was absent at birth from all brain structures except the ependymal cell layer lining the ventricles. The development of NT2 receptor mRNA followed three ontogenetic patterns. The first pattern, involving the majority of the cerebral gray matter, was characterized by a continuous increase from postnatal day 5 (P5) to P30. The second one, involving regions rich in myelinated fibers such as the corpus callosum and lacunosum moleculare layer of the hippocampus, exhibited a pronounced increase between P5 and P10, peaked at P15 and was followed by a plateau or a slight decrease. The third pattern was observed in the ependymal cell layer lining the olfactory and lateral ventricles, where the high labeling already present at birth continued to increase during development. These different developmental patterns could reflect the variety of cells expressing NT2 receptor mRNA, including neurons, protoplasmic astrocytes in gray matter, fibrous astrocytes present in myelinated fibers tracts, and ependymal cells. In contrast, NT1 receptor mRNA, which seems to be associated only with neurons, was highly and transiently expressed during the perinatal period in the cerebral cortex, hippocampus and striatal neuroepithelium. Other regions, notably the ventral tegmental area and substantia nigra compacta, exhibited a gradual increase in NT1 receptor signal, reaching adult levels by P21. Both the differential localization and ontogenetic profiles of NT1 and NT2 receptor mRNAs suggest different involvement of these two receptors in brain functions and development. Copyright 1999 Elsevier Science B.V.

C-Type Lectin Receptors in Asthma

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Sabelo Hadebe

2018-04-01

Full Text Available Asthma is a heterogeneous disease that affects approximately 300 million people worldwide, largely in developed countries. The etiology of the disease is poorly understood, but is likely to involve specific innate and adaptive responses to inhaled microbial components that are found in allergens. Fungal-derived allergens represent a major contributing factor in the initiation, persistence, exacerbation, and severity of allergic asthma. C-type lectin like receptors, such as dectin-1, dectin-2, DC-specific intercellular adhesion molecule 3-grabbing nonintegrin, and mannose receptor, recognize many fungal-derived allergens and other structurally similar allergens derived from house dust mites (HDM. In some cases, the fungal derived allergens have been structurally and functionally identified alongside their respective receptors in both humans and mice. In this review, we discuss recent understanding on how selected fungal and HDM derived allergens as well as their known or unknown receptors shape allergic airway diseases.

Agonist Binding to Chemosensory Receptors: A Systematic Bioinformatics Analysis

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Fabrizio Fierro

2017-09-01

Full Text Available Human G-protein coupled receptors (hGPCRs constitute a large and highly pharmaceutically relevant membrane receptor superfamily. About half of the hGPCRs' family members are chemosensory receptors, involved in bitter taste and olfaction, along with a variety of other physiological processes. Hence these receptors constitute promising targets for pharmaceutical intervention. Molecular modeling has been so far the most important tool to get insights on agonist binding and receptor activation. Here we investigate both aspects by bioinformatics-based predictions across all bitter taste and odorant receptors for which site-directed mutagenesis data are available. First, we observe that state-of-the-art homology modeling combined with previously used docking procedures turned out to reproduce only a limited fraction of ligand/receptor interactions inferred by experiments. This is most probably caused by the low sequence identity with available structural templates, which limits the accuracy of the protein model and in particular of the side-chains' orientations. Methods which transcend the limited sampling of the conformational space of docking may improve the predictions. As an example corroborating this, we review here multi-scale simulations from our lab and show that, for the three complexes studied so far, they significantly enhance the predictive power of the computational approach. Second, our bioinformatics analysis provides support to previous claims that several residues, including those at positions 1.50, 2.50, and 7.52, are involved in receptor activation.

Development of antibodies against the rat brain somatostatin receptor.

Science.gov (United States)

Theveniau, M; Rens-Domiano, S; Law, S F; Rougon, G; Reisine, T

1992-05-15

Somatostatin (SRIF) is a neurotransmitter in the brain involved in the regulation of motor activity and cognition. It induces its physiological actions by interacting with receptors. We have developed antibodies against the receptor to investigate its structural properties. Rabbit polyclonal antibodies were generated against the rat brain SRIF receptor. These antibodies (F4) were able to immunoprecipitate solubilized SRIF receptors from rat brain and the cell line AtT-20. The specificity of the interaction of these antibodies with SRIF receptors was further demonstrated by immunoblotting. F4 detected SRIF receptors of 60 kDa from rat brain and adrenal cortex and the cell lines AtT-20, GH3, and NG-108, which express high densities of SRIF receptors. They did not detect immunoreactive material from rat liver or COS-1, HEPG, or CRL cells, which do not express functional SRIF receptors. In rat brain, 60-kDa immunoreactivity was detected by F4 in the hippocampus, cerebral cortex, and striatum, which have high densities of SRIF receptors. However, F4 did not interact with proteins from cerebellum and brain stem, which express few SRIF receptors. Immunoreactive material cannot be detected in rat pancreas or pituitary, which have been reported to express a 90-kDa SRIF receptor subtype. The selective detection of 60-kDa SRIF receptors by F4 indicates that the 60- and 90-kDa SRIF receptor subtypes are immunologically distinct. The availability of antibodies that selectively detect native and denatured brain SRIF receptors provides us with a feasible approach to clone the brain SRIF receptor gene(s).

Purinergic receptors expressed in human skeletal muscle fibres

DEFF Research Database (Denmark)

Bornø, A; Ploug, Thorkil; Bune, L T

2012-01-01

distribution of purinergic receptors in skeletal muscle fibres. We speculate that the intracellular localization of purinergic receptors may reflect a role in regulation of muscle metabolism; further studies are nevertheless needed to determine the function of the purinergic system in skeletal muscle cells.......Purinergic receptors are present in most tissues and thought to be involved in various signalling pathways, including neural signalling, cell metabolism and local regulation of the microcirculation in skeletal muscles. The present study aims to determine the distribution and intracellular content...... of purinergic receptors in skeletal muscle fibres in patients with type 2 diabetes and age-matched controls. Muscle biopsies from vastus lateralis were obtained from six type 2 diabetic patients and seven age-matched controls. Purinergic receptors were analysed using light and confocal microscopy...

Computer modeling of Cannabinoid receptor type 1

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Sapundzhi Fatima

2018-01-01

Full Text Available Cannabinoid receptors are important class of receptors as they are involved in various physiological processes such as appetite, pain-sensation, mood, and memory. It is important to design receptor-selective ligands in order to treat a particular disorder. The aim of the present study is to model the structure of cannabinoid receptor CB1 and to perform docking between obtained models and known ligands. Two models of CBR1 were prepared with two different methods (Modeller of Chimera and MOE. They were used for docking with GOLD 5.2. It was established a high correlation between inhibitory constant Ki of CB1 cannabinoid ligands and the ChemScore scoring function of GOLD, which concerns both models. This suggests that the models of the CB1 receptors obtained could be used for docking studies and in further investigation and design of new potential, selective and active cannabinoids with the desired effects.

Nociceptin and the nociceptin receptor in learning and memory.

Science.gov (United States)

Andero, Raül

2015-10-01

There are many processes in which the neuropeptide nociceptin/orphanin FQ (N/OFQ or nociceptin) is involved in the brain. The role of nociceptin in learning and memory holds promise in modulating these processes in health and disease in the human brain. This review summarizes the body of research focused on N/OFQ and its specific receptor, the nociceptin receptor (NOP receptor), in learning and memory, and its potential mechanisms of action, in which acetylcholine, NMDA receptor, and noradrenaline may be critical. Finally, the association between NOP receptor and posttraumatic stress disorder (PTSD), a psychiatric disorder with altered fear learning, is examined as one of the potential outcomes resulting from pathological consequences of dysregulation of N/OFQ-NOP receptor in the brain. Copyright © 2015 Elsevier Inc. All rights reserved.

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

Science.gov (United States)

Imai, K; Yoshimura, T

1994-08-01

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

Angiotensin type 2 receptor (AT2R) and receptor Mas

DEFF Research Database (Denmark)

Villela, Daniel; Leonhardt, Julia; Patel, Neal

2015-01-01

The angiotensin type 2 receptor (AT2R) and the receptor Mas are components of the protective arms of the renin-angiotensin system (RAS), i.e. they both mediate tissue protective and regenerative actions. The spectrum of actions of these two receptors and their signalling mechanisms display striki...

Site-Directed Mutagenesis of the Fibronectin Domains in Insulin Receptor-Related Receptor

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Igor E. Deyev

2017-11-01

Full Text Available The orphan insulin receptor-related receptor (IRR, in contrast to its close homologs, the insulin receptor (IR and insulin-like growth factor receptor (IGF-IR can be activated by mildly alkaline extracellular medium. We have previously demonstrated that IRR activation is defined by its extracellular region, involves multiple domains, and shows positive cooperativity with two synergistic sites. By the analyses of point mutants and chimeras of IRR with IR in, we now address the role of the fibronectin type III (FnIII repeats in the IRR pH-sensing. The first activation site includes the intrinsically disordered subdomain ID (646–716 within the FnIII-2 domain at the C-terminus of IRR alpha subunit together with closely located residues L135, G188, R244, H318, and K319 of L1 and C domains of the second subunit. The second site involves residue T582 of FnIII-1 domain at the top of IRR lambda-shape pyramid together with M406, V407, and D408 from L2 domain within the second subunit. A possible importance of the IRR carbohydrate moiety for its activation was also assessed. IRR is normally less glycosylated than IR and IGF-IR. Swapping both FnIII-2 and FnIII-3 IRR domains with those of IR shifted beta-subunit mass from 68 kDa for IRR to about 100 kDa due to increased glycosylation and abolished the IRR pH response. However, mutations of four asparagine residues, potential glycosylation sites in chimera IRR with swapped FnIII-2/3 domains of IR, decreased the chimera glycosylation and resulted in a partial restoration of IRR pH-sensing activity, suggesting that the extensive glycosylation of FnIII-2/3 provides steric hindrance for the alkali-induced rearrangement of the IRR ectodomain.

Amyotrophic Lateral Sclerosis (ALS and Adenosine Receptors

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Ana M. Sebastião

2018-04-01

Full Text Available In the present review we discuss the potential involvement of adenosinergic signaling, in particular the role of adenosine receptors, in amyotrophic lateral sclerosis (ALS. Though the literature on this topic is not abundant, the information so far available on adenosine receptors in animal models of ALS highlights the interest to continue to explore the role of these receptors in this neurodegenerative disease. Indeed, all motor neurons affected in ALS are responsive to adenosine receptor ligands but interestingly, there are alterations in pre-symptomatic or early symptomatic stages that mirror those in advanced disease stages. Information starts to emerge pointing toward a beneficial role of A2A receptors (A2AR, most probably at early disease states, and a detrimental role of caffeine, in clear contrast with what occurs in other neurodegenerative diseases. However, some evidence also exists on a beneficial action of A2AR antagonists. It may happen that there are time windows where A2AR prove beneficial and others where their blockade is required. Furthermore, the same changes may not occur simultaneously at the different synapses. In line with this, it is not fully understood if ALS is a dying back disease or if it propagates in a centrifugal way. It thus seems crucial to understand how motor neuron dysfunction occurs, how adenosine receptors are involved in those dysfunctions and whether the early changes in purinergic signaling are compensatory or triggers for the disease. Getting this information is crucial before starting the design of purinergic based strategies to halt or delay disease progression.

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...

A search for presynaptic inhibitory histamine receptors in guinea-pig tissues: Further H3 receptors but no evidence for H4 receptors.

Science.gov (United States)

Petri, Doris; Schlicker, Eberhard

2016-07-01

The histamine H4 receptor is coupled to Gi/o proteins and expressed on inflammatory cells and lymphoid tissues; it was suggested that this receptor also occurs in the brain or on peripheral neurones. Since many Gi/o protein-coupled receptors, including the H3 receptor, serve as presynaptic inhibitory receptors, we studied whether the sympathetic neurones supplying four peripheral tissues and the cholinergic neurones in the hippocampus from the guinea-pig are equipped with release-modulating H4 and H3 receptors. For this purpose, we preincubated tissue pieces from the aorta, atrium, renal cortex and vas deferens with (3)H-noradrenaline and hippocampal slices with (3)H-choline and determined the electrically evoked tritium overflow. The stimulation-evoked overflow in the five superfused tissues was inhibited by the muscarinic receptor agonist oxotremorine, which served as a positive control, but not affected by the H4 receptor agonist 4-methylhistamine. The H3 receptor agonist R-α-methylhistamine inhibited noradrenaline release in the peripheral tissues without affecting acetylcholine release in the hippocampal slices. Thioperamide shifted the concentration-response curve of histamine in the aorta and the renal cortex to the right, yielding apparent pA2 values of 8.0 and 8.1, respectively, which are close to its affinity at other H3 receptors but higher by one log unit than its pKi at the H4 receptor of the guinea-pig. In conclusion, histamine H4 receptors could not be identified in five experimental models of the guinea-pig that are suited for the detection of presynaptic inhibitory receptors whereas H3 receptors could be shown in the peripheral tissues but not in the hippocampus. This article is part of the Special Issue entitled 'Histamine Receptors'. Copyright © 2015 Elsevier Ltd. All rights reserved.

Identification of fibroblast growth factor receptor 3 (FGFR3 as a protein receptor for botulinum neurotoxin serotype A (BoNT/A.

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Birgitte P S Jacky

Full Text Available Botulinum neurotoxin serotype A (BoNT/A causes transient muscle paralysis by entering motor nerve terminals (MNTs where it cleaves the SNARE protein Synaptosomal-associated protein 25 (SNAP25206 to yield SNAP25197. Cleavage of SNAP25 results in blockage of synaptic vesicle fusion and inhibition of the release of acetylcholine. The specific uptake of BoNT/A into pre-synaptic nerve terminals is a tightly controlled multistep process, involving a combination of high and low affinity receptors. Interestingly, the C-terminal binding domain region of BoNT/A, HC/A, is homologous to fibroblast growth factors (FGFs, making it a possible ligand for Fibroblast Growth Factor Receptors (FGFRs. Here we present data supporting the identification of Fibroblast Growth Factor Receptor 3 (FGFR3 as a high affinity receptor for BoNT/A in neuronal cells. HC/A binds with high affinity to the two extra-cellular loops of FGFR3 and acts similar to an agonist ligand for FGFR3, resulting in phosphorylation of the receptor. Native ligands for FGFR3; FGF1, FGF2, and FGF9 compete for binding to FGFR3 and block BoNT/A cellular uptake. These findings show that FGFR3 plays a pivotal role in the specific uptake of BoNT/A across the cell membrane being part of a larger receptor complex involving ganglioside- and protein-protein interactions.

The Elastin Receptor Complex: a unique matricellular receptor with high anti-tumoral potential

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Amandine eScandolera

2016-03-01

Full Text Available Elastin, one of the longest-lived proteins, confers elasticity to tissues with high mechanical constraints. During aging or pathophysiological conditions such as cancer progression, this insoluble polymer of tropoelastin undergoes an important degradation leading to the release of bioactive elastin-derived peptides (EDP, named elastokines. EDP exhibit several biological functions able to drive tumor development by regulating cell proliferation, invasion, survival, angiogenesis, and matrix metalloproteinase expression in various tumor and stromal cells. Although several receptors have been suggested to bind elastokines (αvβ3 and αvβ5 integrins, galectin-3, their main receptor remains the Elastin Receptor Complex (ERC. This heterotrimer comprises a peripheral subunit, named Elastin Binding Protein (EBP, associated to the Protective Protein/Cathepsin A (PPCA. The latter is bound to a membrane-associated protein called Neuraminidase-1 (Neu-1. The pro-tumoral effects of elastokines have been linked to their binding onto EBP. Additionally, Neu-1 sialidase activity is essential for their signal transduction. Consistently, EDP-EBP interaction and Neu-1 activity emerge as original anti-tumoral targets. Interestingly, besides its direct involvement in cancer progression, the ERC also regulates diabetes outcome and thrombosis, an important risk factor for cancer development and a vascular process highly increased in patients suffering from cancer. In this review, we will describe ERC and elastokines involvement in cancer development suggesting that this unique receptor would be a promising therapeutic target. We will also discuss the pharmacological concepts aiming at blocking its pro-tumoral activities. Finally, its emerging role in cancer-associated complications and pathologies such as diabetes and thrombotic events will be also considered.

Non-conventional Frizzled ligands and Wnt receptors.

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Hendrickx, Marijke; Leyns, Luc

2008-05-01

The Wnt family of secreted signaling factors plays numerous roles in embryonic development and in stem cell biology. In the adult, Wnt signaling is involved in tissue homeostasis and mutations that lead to the overexpression of Wnt can be linked to cancer. Wnt signaling is transduced intracellularly by the Frizzled (Fzd) family of receptors. In the canonical pathway, accumulation of beta-catenin and the subsequent formation of a complex with T cell factors (TCF) or lymphoid enhancing factors (Lef) lead to target gene activation. The identification of Ryk as an alternative Wnt receptor and the discovery of the novel Fzd ligands Norrie disease protein (NDP) and R-Spondin, changed the traditional view of Wnts binding to Fzd receptors. Mouse R-Spondin cooperates with Wnt signaling and Low density lipoprotein (LDL) receptor related protein (LRP) to activate beta-catenin dependent gene expression and is involved in processes such as limb and placental development in the mouse. NDP is the product of the Norrie disease gene and controls vascular development in the retina, inner ear and in the female reproductive system during pregnancy. In this review a functional overview of the interactions of the different Wnt and non-Wnt ligands with the Fzd receptors is given as well as a survey of Wnts binding to Ryk and we discuss the biological significance of these interactions.

Functional characterization of bursicon receptor and genome-wide analysis for identification of genes affected by bursicon receptor RNAi

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Bai, Hua; Palli, Subba R.

2010-01-01

Bursicon is an insect neuropeptide hormone that is secreted from the central nervous system into the hemolymph and initiates cuticle tanning. The receptor for bursicon is encoded by the rickets (rk) gene and belongs to the G protein-coupled receptor (GPCR) superfamily. The bursicon and its receptor regulate cuticle tanning as well as wing expansion after adult eclosion. However, the molecular action of bursicon signaling remains unclear. We utilized RNA interference (RNAi) and microarray to study the function of the bursicon receptor (Tcrk) in the model insect, Tribolium castaneum. The data included here showed that in addition to cuticle tanning and wing expansion reported previously, Tcrk is also required for development and expansion of integumentary structures and adult eclosion. Using custom microarrays, we identified 24 genes that are differentially expressed between Tcrk RNAi and control insects. Knockdown in the expression of one of these genes, TC004091, resulted in the arrest of adult eclosion. Identification of genes that are involved in bursicon receptor mediated biological processes will provide tools for future studies on mechanisms of bursicon action. PMID:20457145

Real-Time G-Protein-Coupled Receptor Imaging to Understand and Quantify Receptor Dynamics

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María S. Aymerich

2011-01-01

Full Text Available Understanding the trafficking of G-protein-coupled receptors (GPCRs and their regulation by agonists and antagonists is fundamental to develop more effective drugs. Optical methods using fluorescent-tagged receptors and spinning disk confocal microscopy are useful tools to investigate membrane receptor dynamics in living cells. The aim of this study was to develop a method to characterize receptor dynamics using this system which offers the advantage of very fast image acquisition with minimal cell perturbation. However, in short-term assays photobleaching was still a problem. Thus, we developed a procedure to perform a photobleaching-corrected image analysis. A study of short-term dynamics of the long isoform of the dopamine type 2 receptor revealed an agonist-induced increase in the mobile fraction of receptors with a rate of movement of 0.08 μm/s For long-term assays, the ratio between the relative fluorescence intensity at the cell surface versus that in the intracellular compartment indicated that receptor internalization only occurred in cells co-expressing G protein-coupled receptor kinase 2. These results indicate that the lateral movement of receptors and receptor internalization are not directly coupled. Thus, we believe that live imaging of GPCRs using spinning disk confocal image analysis constitutes a powerful tool to study of receptor dynamics.

Analgesic and anti-inflammatory effects of honey: the involvement of autonomic receptors.

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Owoyele, Bamidele Victor; Oladejo, Rasheed Olajiire; Ajomale, Kayode; Ahmed, Rasheedat Omotayo; Mustapha, Abdulrasheed

2014-03-01

The use of honey for therapeutic purposes is on the increase and many studies have shown that honey has the ability to influence biological systems including pain transmission. Therefore, this study was designed to investigate the analgesic and anti-inflammatory effects of honey and the effects of concurrent administration of autonomic nervous system blocking drugs. Studies on analgesic activities was carried out using hotplate and formalin-induced paw licking models while the anti-inflammatory activity was by the carrageenan paw oedema method. Animals were distributed into six groups consisting of five animals each. They were administered saline, honey (600 mg/kg), indomethacin (5 mg/kg), autonomic blockers (3 μg/kg of tamsulosin, 20 mg/kg (intraperitoneally) of propranolol, 2 ml/kg of atropine or 10 mg/kg (intra muscularly) of hexamethonium) or honey (200 and 600 mg/kg) with one of the blockers. The results showed that honey reduced pain perception especially inflammatory pain and the administration of tamsulosin and propranolol spared the effect of honey. Hexamethonium also spared the effects of honey at the early and late phases of the test while atropine only inhibited the early phase of the test. However, atropine and hexamethonium spared the anti-inflammatory effects of honey but tamsulosin abolished the effects while propranolol only abolished the anti-inflammatory effects at the peak of the inflammation. The results suggest the involvement of autonomic receptors in the anti-nociceptive and anti-inflammatory effects of honey although the level of involvement depends on the different types of the receptors.

Receptor assay

Energy Technology Data Exchange (ETDEWEB)

Kato, K; Ibayashi, H [Kyushu Univ., Fukuoka (Japan). Faculty of Medicine

1975-05-01

This paper summarized present status and problems of analysis of hormone receptor and a few considerations on clinical significance of receptor abnormalities. It was pointed that in future clinical field quantitative and qualitative analysis of receptor did not remain only in the etiological discussion, but that it was an epoch-making field of investigation which contained the possiblity of artificial change of sensitivity of living body on drugs and the development connected directly with treatment of various diseases.

Differential Expression of Chemokine Receptors and their Roles in Cancer Imaging

Energy Technology Data Exchange (ETDEWEB)

Nimmagadda, Sridhar, E-mail: snimmag1@jhmi.edu [Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD (United States)

2012-05-30

Chemokine/chemokine receptor interactions play diverse roles in cell migration and homeostasis. Emerging evidence suggests that cancer cells co-opt chemokine networks for survival, proliferation, immune evasion, and metastasis. Most of the chemokine receptors are reported to be involved in tumor progression. Given their extensive implication in cancer progression, several chemokine receptor/ligand axes are considered as potential therapeutic targets. This review provides a survey of chemokine receptor expression in cancer and evaluates the potential of chemokine receptor imaging as a tool for molecular characterization of cancer.

Differential Expression of Chemokine Receptors and their Roles in Cancer Imaging

International Nuclear Information System (INIS)

Nimmagadda, Sridhar

2012-01-01

Chemokine/chemokine receptor interactions play diverse roles in cell migration and homeostasis. Emerging evidence suggests that cancer cells co-opt chemokine networks for survival, proliferation, immune evasion, and metastasis. Most of the chemokine receptors are reported to be involved in tumor progression. Given their extensive implication in cancer progression, several chemokine receptor/ligand axes are considered as potential therapeutic targets. This review provides a survey of chemokine receptor expression in cancer and evaluates the potential of chemokine receptor imaging as a tool for molecular characterization of cancer.

Receptor mapping in psychiatric patients with SPECT

International Nuclear Information System (INIS)

Schlegel, S.

1997-01-01

This paper summarizes some data of our studies with the single-photon-emission-computerized tomography (SPECT), focussing on the dopamine-D2- and the benzodiazepine receptor mapping. Benzodiazepine receptors: Central benzodiazepine receptors (BZr) can be visualized with iomazenil which is an analogue of the benzodiazepine antagonist flumazenil, labeled with 123-iodine. Since the involvement of the BZr system is discussed in the pathogenesis of anxiety and depression, patients with these disorders were investigated. A third study investigated the BZr-occupancy during benzodiazepine treatment (lorazepam). Results: (a) Patients with panic disorders had lower iomazenil uptake values compared to epileptic patients. (b) Depressed patients showed a positive correlation between severity of illness and frontal uptake. (c) BZr occupancy during lorazepam treatment was measurable, but not associated with lorazepam plasma levels. Dopamine-D2-receptors: With 123-I-iodobenzamide (IBZM), and iodine-labeled dopamine receptor ligand, the D2 receptor density can be measured by a semiquantitative approach (striatum/frontal cortex=ST/FC). Therefore, we investigated the D2-receptor occupancy during treatment with typical and atypical neuroleptics in relationship to dosages (normalized with different formulas of chlorpromazine equivalents), side effects, and prolactin plasma levels. Results: Dependent on the selected formula for chlorpromazine equivalents, the ST/FC ratio was correlated with dosages. Side effects and prolactin plasma levels showed a negative association with lower ST/FC ratios. (orig.) [de

Calcitonin and calcitonin receptor-like receptors: common themes with family B GPCRs?

Science.gov (United States)

Barwell, James; Gingell, Joseph J; Watkins, Harriet A; Archbold, Julia K; Poyner, David R; Hay, Debbie L

2012-05-01

The calcitonin receptor (CTR) and calcitonin receptor-like receptor (CLR) are two of the 15 human family B (or Secretin-like) GPCRs. CTR and CLR are of considerable biological interest as their pharmacology is moulded by interactions with receptor activity-modifying proteins. They also have therapeutic relevance for many conditions, such as osteoporosis, diabetes, obesity, lymphatic insufficiency, migraine and cardiovascular disease. In light of recent advances in understanding ligand docking and receptor activation in both the family as a whole and in CLR and CTR specifically, this review reflects how applicable general family B GPCR themes are to these two idiosyncratic receptors. We review the main functional domains of the receptors; the N-terminal extracellular domain, the juxtamembrane domain and ligand interface, the transmembrane domain and the intracellular C-terminal domain. Structural and functional findings from the CLR and CTR along with other family B GPCRs are critically appraised to gain insight into how these domains may function. The ability for CTR and CLR to interact with receptor activity-modifying proteins adds another level of sophistication to these receptor systems but means careful consideration is needed when trying to apply generic GPCR principles. This review encapsulates current thinking in the realm of family B GPCR research by highlighting both conflicting and recurring themes and how such findings relate to two unusual but important receptors, CTR and CLR. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

In vivo study of central receptors in man using pet

International Nuclear Information System (INIS)

Baron, J.C.

1986-09-01

Central neurotransmitter systems and receptors are intimately involved in the mechanism of several neurologic and phychiatric disorders. Although neurotransmitter concentration and receptor function can be measured regionnally post-mortem, studies performed during life may provide insight into changes at early stages of the disease as well as follow-up data on, and pharmacological modification of, such changes. Positron Tomography (PET) allows to monitor non-invasively the time-course of regional tissue tracer concentration following administration of a radioactive drug. If the latter is known to interact selectively with specific binding sites, it can be used to probe in vivo the regional distribution and affinity of the receptors involved. As shown in this progress report, several receptor systems can now be studied reliably in humans, using PET

Steroid receptors and their ligands: Effects on male gamete functions

International Nuclear Information System (INIS)

Aquila, Saveria; De Amicis, Francesca

2014-01-01

In recent years a new picture of human sperm biology is emerging. It is now widely recognized that sperm contain nuclear encoded mRNA, mitochondrial encoded RNA and different transcription factors including steroid receptors, while in the past sperm were considered incapable of transcription and translation. One of the main targets of steroid hormones and their receptors is reproductive function. Expression studies on Progesterone Receptor, estrogen receptor, androgen receptor and their specific ligands, demonstrate the presence of these systems in mature spermatozoa as surface but also as nuclear conventional receptors, suggesting that both systemic and local steroid hormones, through sperm receptors, may influence male reproduction. However, the relationship between the signaling events modulated by steroid hormones and sperm fertilization potential as well as the possible involvement of the specific receptors are still controversial issues. The main line of this review highlights the current research in human sperm biology examining new molecular systems of response to the hormones as well as specific regulatory pathways controlling sperm cell fate and biological functions. Most significant studies regarding the identification of steroid receptors are reported and the mechanistic insights relative to signaling pathways, together with the change in sperm metabolism energy influenced by steroid hormones are discussed.The reviewed evidences suggest important effects of Progesterone, Estrogen and Testosterone and their receptors on spermatozoa and implicate the involvement of both systemic and local steroid action in the regulation of male fertility potential. - Highlights: • One of the main targets of steroid hormones and their receptors is reproductive function. • Pg/PR co-work to stimulate enzymatic activities to sustain a capacitation process. • E2/ERs regulate sperm motility, capacitation and acrosome reaction and act as survival factors. • Androgens

Steroid receptors and their ligands: Effects on male gamete functions

Energy Technology Data Exchange (ETDEWEB)

Aquila, Saveria; De Amicis, Francesca, E-mail: francesca.deamicis@unical.it

2014-11-01

In recent years a new picture of human sperm biology is emerging. It is now widely recognized that sperm contain nuclear encoded mRNA, mitochondrial encoded RNA and different transcription factors including steroid receptors, while in the past sperm were considered incapable of transcription and translation. One of the main targets of steroid hormones and their receptors is reproductive function. Expression studies on Progesterone Receptor, estrogen receptor, androgen receptor and their specific ligands, demonstrate the presence of these systems in mature spermatozoa as surface but also as nuclear conventional receptors, suggesting that both systemic and local steroid hormones, through sperm receptors, may influence male reproduction. However, the relationship between the signaling events modulated by steroid hormones and sperm fertilization potential as well as the possible involvement of the specific receptors are still controversial issues. The main line of this review highlights the current research in human sperm biology examining new molecular systems of response to the hormones as well as specific regulatory pathways controlling sperm cell fate and biological functions. Most significant studies regarding the identification of steroid receptors are reported and the mechanistic insights relative to signaling pathways, together with the change in sperm metabolism energy influenced by steroid hormones are discussed.The reviewed evidences suggest important effects of Progesterone, Estrogen and Testosterone and their receptors on spermatozoa and implicate the involvement of both systemic and local steroid action in the regulation of male fertility potential. - Highlights: • One of the main targets of steroid hormones and their receptors is reproductive function. • Pg/PR co-work to stimulate enzymatic activities to sustain a capacitation process. • E2/ERs regulate sperm motility, capacitation and acrosome reaction and act as survival factors. • Androgens

Hyperalgesic effect induced by barbiturates, midazolam and ethanol: pharmacological evidence for GABA-A receptor involvement

Directory of Open Access Journals (Sweden)

M.A.K.F. Tatsuo

1997-02-01

Full Text Available The involvement of GABA-A receptors in the control of nociception was studied using the tail-flick test in rats. Non-hypnotic doses of the barbiturates phenobarbital (5-50 mg/kg, pentobarbital (17-33 mg/kg, and thiopental (7.5-30 mg/kg, of the benzodiazepine midazolam (10 mg/kg or of ethanol (0.4-1.6 g/kg administered by the systemic route reduced the latency for the tail-flick response, thus inducing a 'hyperalgesic' state in the animals. In contrast, non-convulsant doses of the GABA-A antagonist picrotoxin (0.12-1.0 mg/kg administered systemically induced an increase in the latency for the tail-flick response, therefore characterizing an 'antinociceptive' state. Previous picrotoxin (0.12 mg/kg treatment abolished the hyperalgesic state induced by effective doses of the barbiturates, midazolam or ethanol. Since phenobarbital, midazolam and ethanol reproduced the described hyperalgesic effect of GABA-A-specific agonists (muscimol, THIP, which is specifically antagonized by the GABA-A antagonist picrotoxin, our results suggest that GABA-A receptors are tonically involved in the modulation of nociception in the rat central nervous system

Molecular modeling of ligand-receptor interactions in the OR5 olfactory receptor.

Science.gov (United States)

Singer, M S; Shepherd, G M

1994-06-02

Olfactory receptors belong to the superfamily of seven transmembrane domain, G protein-coupled receptors. In order to begin analysis of mechanisms of receptor activation, a computer model of the OR5 olfactory receptor has been constructed and compared with other members of this superfamily. We have tested docking of the odor molecule lyral, which is known to activate the OR5 receptor. The results point to specific ligand-binding residues on helices III through VII that form a binding pocket in the receptor. Some of these residues occupy sequence positions identical to ligand-binding residues conserved among other superfamily members. The results provide new insights into possible molecular mechanisms of odor recognition and suggest hypotheses to guide future experimental studies using site-directed mutagenesis.

Involvement of Gaba and Cannabinoid Receptors in Central Food Intake Regulation in Neonatal Layer Chicks: Role of CB1 and Gabaa Receptors

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M Zendehdel

Full Text Available ABSTRACT Feeding behavior is regulated via a complex network which interacts via diverse signals from central and peripheral tissues. Endocannabinoids modulate release of GABA in a variety of regions of the central nervous system. Endocannabinoids and GABAergic system have an important role in the central regulation of appetite. Thus, the present study examines the possible interaction of central canabinoidergic and GABAergic systems on food intake in 3-h food-deprived (FD3 neonatal layer-type chicks. The results of this study showed that intracerebroventricular (ICV injection of 2-AG (2-Arachidonoylglycerol, selective CB1 receptors agonist, 2µg significantly increased food intake and this effect of 2-AG was attenuated by Picrotoxin (GABAA antagonist, 0.5µg (P0.05. Also, hyperphagic effect of CB65 (CB2 receptors agonist, 1.25µg was not affected by Picrotoxin or CGP54626 (p>0.05. Moreover, the food intake of chicks was significantly increased by ICV injection of GABAA agonist (Gaboxadol, 0.2 µg and SR141716A (CB1 receptors antagonist, 6.25µg significantly decreased Gaboxadol-induced hyperphagia (P0.05. These data showed there might be an interaction between central cannabinoidergic and GABAergic systems via CB1 and GABAA receptors in control of food intake in neonatal layer chicks.

Involvement of the histamine H4 receptor in clozapine-induced hematopoietic toxicity: Vulnerability under granulocytic differentiation of HL-60 cells

International Nuclear Information System (INIS)

Goto, Aya; Mouri, Akihiro; Nagai, Tomoko; Yoshimi, Akira; Ukigai, Mako; Tsubai, Tomomi; Hida, Hirotake; Ozaki, Norio; Noda, Yukihiro

2016-01-01

Clozapine is an effective antipsychotic for treatment-resistant schizophrenia, but can cause fatal hematopoietic toxicity as agranulocytosis. To elucidate the mechanism of hematopoietic toxicity induced by clozapine, we developed an in vitro assay system using HL-60 cells, and investigated the effect on hematopoiesis. HL-60 cells were differentiated by all-trans retinoic acid (ATRA) into three states according to the following hematopoietic process: undifferentiated HL-60 cells, those undergoing granulocytic ATRA-differentiation, and ATRA-differentiated granulocytic cells. Hematopoietic toxicity was evaluated by analyzing cell survival, cell proliferation, granulocytic differentiation, apoptosis, and necrosis. In undifferentiated HL-60 cells and ATRA-differentiated granulocytic cells, both clozapine (50 and 100 μM) and doxorubicin (0.2 µM) decreased the cell survival rate, but olanzapine (1–100 µM) did not. Under granulocytic differentiation for 5 days, clozapine, even at a concentration of 25 μM, decreased survival without affecting granulocytic differentiation, increased caspase activity, and caused apoptosis rather than necrosis. Histamine H 4 receptor mRNA was expressed in HL-60 cells, whereas the expression decreased under granulocytic ATRA-differentiation little by little. Both thioperamide, a histamine H 4 receptor antagonist, and DEVD-FMK, a caspase-3 inhibitor, exerted protection against clozapine-induced survival rate reduction, but not of live cell counts. 4-Methylhistamine, a histamine H 4 receptor agonist, decreased the survival rate and live cell counts, as did clozapine. HL-60 cells under granulocytic differentiation are vulnerable under in vitro assay conditions to hematopoietic toxicity induced by clozapine. Histamine H 4 receptor is involved in the development of clozapine-induced hematopoietic toxicity through apoptosis, and may be a potential target for preventing its occurrence through granulocytic differentiation. - Highlights: • HL-60

Effect of ATP on intracellular pH in pancreatic ducts involves P2X7 receptors

DEFF Research Database (Denmark)

Henriksen, Katerine L; Novak, Ivana

2003-01-01

which P2 receptors might be involved. Ducts were obtained from rat pancreas, and the pH sensitive fluorophore BCECF was used to measure pHi and recovery rates from cellular acidosis induced by ammonium pre-pulses. In order to reveal Na+/H+ exchange, Cl-/HCO3- exchange or a Na+-HCO3- cotransport...

Medicinal Chemistry of Competitive Kainate Receptor Antagonists

Science.gov (United States)

2010-01-01

Kainic acid (KA) receptors belong to the group of ionotropic glutamate receptors and are expressed throughout in the central nervous system (CNS). The KA receptors have been shown to be involved in neurophysiological functions such as mossy fiber long-term potentiation (LTP) and synaptic plasticity and are thus potential therapeutic targets in CNS diseases such as schizophrenia, major depression, neuropathic pain and epilepsy. Extensive effort has been made to develop subtype-selective KA receptor antagonists in order to elucidate the physiological function of each of the five subunits known (GluK1−5). However, to date only selective antagonists for the GluK1 subunit have been discovered, which underlines the strong need for continued research in this area. The present review describes the structure−activity relationship and pharmacological profile for 10 chemically distinct classes of KA receptor antagonists comprising, in all, 45 compounds. To the medicinal chemist this information will serve as reference guidance as well as an inspiration for future effort in this field. PMID:22778857

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.

Receptor protection studies comparing recombinant and native nicotinic receptors: Evidence for a subpopulation of mecamylamine-sensitive native alpha3beta4* nicotinic receptors.

Science.gov (United States)

Free, R Benjamin; Kaser, Daniel J; Boyd, R Thomas; McKay, Dennis B

2006-01-09

Studies involving receptor protection have been used to define the functional involvement of specific receptor subtypes in tissues expressing multiple receptor subtypes. Previous functional studies from our laboratory demonstrate the feasibility of this approach when applied to neuronal tissues expressing multiple nicotinic acetylcholine receptors (nAChRs). In the current studies, the ability of a variety of nAChR agonists and antagonists to protect native and recombinant alpha3beta4 nAChRs from alkylation were investigated using nAChR binding techniques. Alkylation of native alpha3beta4* nAChRs from membrane preparations of bovine adrenal chromaffin cells resulted in a complete loss of specific [(3)H]epibatidine binding. This loss of binding to native nAChRs was preventable by pretreatment with the agonists, carbachol or nicotine. The partial agonist, cytisine, produced partial protection. Several nAChR antagonists were also tested for their ability to protect. Hexamethonium and decamethonium were without protective activity while mecamylamine and tubocurarine were partially effective. Addition protection studies were performed on recombinant alpha3beta4 nAChRs. As with native alpha3beta4* nAChRs, alkylation produced a complete loss of specific [(3)H]epibatidine binding to recombinant alpha3beta4 nAChRs which was preventable by pretreatment with nicotine. However, unlike native alpha3beta4* nAChRs, cytisine and mecamylamine, provide no protection for alkylation. These results highlight the differences between native alpha3beta4* nAChRs and recombinant alpha3beta4 nAChRs and support the use of protection assays to characterize native nAChR subpopulations.

Liver X receptor α and farnesoid X receptor are major transcriptional regulators of OATP1B1.

Science.gov (United States)

Meyer Zu Schwabedissen, Henriette E; Böttcher, Kerstin; Chaudhry, Amarjit; Kroemer, Heyo K; Schuetz, Erin G; Kim, Richard B

2010-11-01

Organic anion transporting polypeptide 1B1 (OATP1B1) is a liver-enriched transporter involved in the hepatocellular uptake of many endogenous molecules and several structurally divergent drugs in clinical use. Although OATP1B1 coding region polymorphisms are known to make an impact on substrate drug disposition in humans, little is known regarding the mechanisms underlying the transcriptional regulation of this transporter. In this study, we note that messenger RNA (mRNA) expression of OATP1B1 in a large human liver bank exhibited marked interindividual variability that was not associated with coding region polymorphisms. Accordingly, we hypothesized that such variability in expression is reflective of nuclear receptor-mediated transcriptional regulation of this transporter. We tested prototypical ligands for the nuclear receptors pregnane X receptor (PXR), constitutive androstane receptor (CAR), liver X receptor (LXR) α, and farnesoid X receptor (FXR) in a human hepatoma-derived cell line and noted induction of OATP1B1 mRNA when the cells were treated with LXRα or FXR ligands. To confirm a direct role for LXRα and FXR to OATP1B1 expression, we performed detailed promoter analysis and cell-based reporter gene assays resulting in the identification of two functional FXR response elements and one LXRα response element. The direct interaction between nuclear receptors with the identified response elements was assessed using chromatin immunoprecipitation assays. Using isolated primary human hepatocytes, we show that LXRα or FXR agonists, but not PXR or CAR agonists, are capable of OATP1B1 induction. We note that OATP1B1 transcriptional regulation is under dual nuclear receptor control through the oxysterol sensing LXRα and the bile acid sensor FXR. Accordingly, the interplay between OATP1B1 and nuclear receptors may play an important and heretofore unrecognized role during cholestasis, drug-induced liver injury, and OATP1B1 induction-related drug interactions.

Receptor downregulation and desensitization enhance the information processing ability of signalling receptors

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Resat Haluk

2007-11-01

Full Text Available Abstract Background In addition to initiating signaling events, the activation of cell surface receptors also triggers regulatory processes that restrict the duration of signaling. Acute attenuation of signaling can be accomplished either via ligand-induced internalization of receptors (endocytic downregulation or via ligand-induced receptor desensitization. These phenomena have traditionally been viewed in the context of adaptation wherein the receptor system enters a refractory state in the presence of sustained ligand stimuli and thereby prevents the cell from over-responding to the ligand. Here we use the epidermal growth factor receptor (EGFR and G-protein coupled receptors (GPCR as model systems to respectively examine the effects of downregulation and desensitization on the ability of signaling receptors to decode time-varying ligand stimuli. Results Using a mathematical model, we show that downregulation and desensitization mechanisms can lead to tight and efficient input-output coupling thereby ensuring synchronous processing of ligand inputs. Frequency response analysis indicates that upstream elements of the EGFR and GPCR networks behave like low-pass filters with the system being able to faithfully transduce inputs below a critical frequency. Receptor downregulation and desensitization increase the filter bandwidth thereby enabling the receptor systems to decode inputs in a wider frequency range. Further, system-theoretic analysis reveals that the receptor systems are analogous to classical mechanical over-damped systems. This analogy enables us to metaphorically describe downregulation and desensitization as phenomena that make the systems more resilient in responding to ligand perturbations thereby improving the stability of the system resting state. Conclusion Our findings suggest that in addition to serving as mechanisms for adaptation, receptor downregulation and desensitization can play a critical role in temporal information

The role of striatal NMDA receptors in drug addiction.

Science.gov (United States)

Ma, Yao-Ying; Cepeda, Carlos; Cui, Cai-Lian

2009-01-01

The past decade has witnessed an impressive accumulation of evidence indicating that the excitatory amino acid glutamate and its receptors, in particular the N-methyl-D-aspartate (NMDA) receptor subtype, play an important role in drug addiction. Various lines of research using animal models of drug addiction have demonstrated that drug-induced craving is accompanied by significant upregulation of NR2B subunit expression. Furthermore, selective blockade of NR2B-containing NMDA receptors in the striatum, especially in the nucleus accumbens (NAc) can inhibit drug craving and reinstatement. The purpose of this review is to examine the role of striatal NMDA receptors in drug addiction. After a brief description of glutamatergic innervation and NMDA receptor subunit distribution in the striatum, we discuss potential mechanisms to explain the role of striatal NMDA receptors in drug addiction by elucidating signaling cascades involved in the regulation of subunit expression and redistribution, phosphorylation of receptor subunits, as well as activation of intracellular signals triggered by drug experience. Understanding the mechanisms regulating striatal NMDA receptor changes in drug addiction will provide more specific and rational targets to counteract the deleterious effects of drug addiction.

Low 5-HT1B receptor binding in the migraine brain

DEFF Research Database (Denmark)

Deen, Marie; Hansen, Hanne D; Hougaard, Anders

2018-01-01

Background The pathophysiology of migraine may involve dysfunction of serotonergic signaling. In particular, the 5-HT1B receptor is considered a key player due to the efficacy of 5-HT1B receptor agonists for treatment of migraine attacks. Aim To examine the cerebral 5-HT1B receptor binding....... Patients who reported migraine brain regions involved in pain modulation as regions of interest and applied a latent variable model (LVM) to assess the group effect on binding across these regions. Results Our data...... support a model wherein group status predicts the latent variable ( p = 0.038), with migraine patients having lower 5-HT1B receptor binding across regions compared to controls. Further, in a whole-brain voxel-based analysis, time since last migraine attack correlated positively with 5-HT1B receptor...

Epilepsy, E/I balance and GABAA receptor plasticity

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Jean-Marc Fritschy

2008-03-01

Full Text Available GABAA receptors mediate most of the fast inhibitory transmission in the CNS. They form heteromeric complexes assembled from a large family of subunit genes. The existence of multiple GABAA receptor subtypes differing in subunit composition, localization and functional properties underlies their role for fi ne-tuning of neuronal circuits and genesis of network oscillations. The differential regulation of GABAA receptor subtypes represents a major facet of homeostatic synaptic plasticity and contributes to the excitation/inhibition (E/I balance under physiological conditions and upon pathological challenges. The purpose of this review is to discuss recent fi ndings highlighting the signifi cance of GABAA receptor heterogeneity for the concept of E/I balance and its relevance for epilepsy. Specifi cally, we address the following issues: (1 role for tonic inhibition, mediated by extrasynaptic GABAA receptors, for controlling neuronal excitability; (2 signifi cance of chloride ion transport for maintenance of the E/I balance in adult brain; and (3 molecular mechanisms underlying GABAA receptor regulation (traffi cking, posttranslational modifi cation, gene transcription that are important for homoeostatic plasticity. Finally, the relevance of these fi ndings is discussed in light of the involvement of GABAA receptors in epileptic disorders, based on recent experimental studies of temporal lobe epilepsy (TLE and absence seizures and on the identifi cation of mutations in GABAA receptor subunit genes underlying familial forms of epilepsy.

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.

Purinergic Receptors in Ocular Inflammation

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Ana Guzman-Aranguez

2014-01-01

Full Text Available Inflammation is a complex process that implies the interaction between cells and molecular mediators, which, when not properly “tuned,” can lead to disease. When inflammation affects the eye, it can produce severe disorders affecting the superficial and internal parts of the visual organ. The nucleoside adenosine and nucleotides including adenine mononucleotides like ADP and ATP and dinucleotides such as P1,P4-diadenosine tetraphosphate (Ap4A, and P1,P5-diadenosine pentaphosphate (Ap5A are present in different ocular locations and therefore they may contribute/modulate inflammatory processes. Adenosine receptors, in particular A2A adenosine receptors, present anti-inflammatory action in acute and chronic retinal inflammation. Regarding the A3 receptor, selective agonists like N6-(3-iodobenzyl-5′-N-methylcarboxamidoadenosine (CF101 have been used for the treatment of inflammatory ophthalmic diseases such as dry eye and uveoretinitis. Sideways, diverse stimuli (sensory stimulation, large intraocular pressure increases can produce a release of ATP from ocular sensory innervation or after injury to ocular tissues. Then, ATP will activate purinergic P2 receptors present in sensory nerve endings, the iris, the ciliary body, or other tissues surrounding the anterior chamber of the eye to produce uveitis/endophthalmitis. In summary, adenosine and nucleotides can activate receptors in ocular structures susceptible to suffer from inflammatory processes. This involvement suggests the possible use of purinergic agonists and antagonists as therapeutic targets for ocular inflammation.

Glutamate receptor agonists

DEFF Research Database (Denmark)

Vogensen, Stine Byskov; Greenwood, Jeremy R; Bunch, Lennart

2011-01-01

The neurotransmitter (S)-glutamate [(S)-Glu] is responsible for most of the excitatory neurotransmission in the central nervous system. The effect of (S)-Glu is mediated by both ionotropic and metabotropic receptors. Glutamate receptor agonists are generally a-amino acids with one or more...... stereogenic centers due to strict requirements in the agonist binding pocket of the activated state of the receptor. By contrast, there are many examples of achiral competitive antagonists. The present review addresses how stereochemistry affects the activity of glutamate receptor ligands. The review focuses...... mainly on agonists and discusses stereochemical and conformational considerations as well as biostructural knowledge of the agonist binding pockets, which is useful in the design of glutamate receptor agonists. Examples are chosen to demonstrate how stereochemistry not only determines how the agonist...

Pharmacology and function of melatonin receptors

International Nuclear Information System (INIS)

Dubocovich, M.L.

1988-01-01

The hormone melatonin is secreted primarily from the pineal gland, with highest levels occurring during the dark period of a circadian cycle. This hormone, through an action in the brain, appears to be involved in the regulation of various neural and endocrine processes that are cued by the daily change in photoperiod. This article reviews the pharmacological characteristics and function of melatonin receptors in the central nervous system, and the role of melatonin in mediating physiological functions in mammals. Melatonin and melatonin agonists, at picomolar concentrations, inhibit the release of dopamine from retina through activation of a site that is pharmacologically different from a serotonin receptor. These inhibitory effects are antagonized by the novel melatonin receptor antagonist luzindole (N-0774), which suggests that melatonin activates a presynaptic melatonin receptor. In chicken and rabbit retina, the pharmacological characteristics of the presynaptic melatonin receptor and the site labeled by 2-[125I]iodomelatonin are identical. It is proposed that 2-[125I]iodomelatonin binding sites (e.g., chicken brain) that possess the pharmacological characteristics of the retinal melatonin receptor site (order of affinities: 2-iodomelatonin greater than 6-chloromelatonin greater than or equal to melatonin greater than or equal to 6,7-di-chloro-2-methylmelatonin greater than 6-hydroxymelatonin greater than or equal to 6-methoxymelatonin greater than N-acetyltryptamine greater than or equal to luzindole greater than N-acetyl-5-hydroxytryptamine greater than 5-methoxytryptamine much greater than 5-hydroxytryptamine) be classified as ML-1 (melatonin 1). The 2-[125I]iodomelatonin binding site of hamster brain membranes possesses different binding and pharmacological characteristics from the retinal melatonin receptor site and should be classified as ML-2. 64 references

5-Hydroxytryptamine 4 Receptor in the Endothelial Cells

DEFF Research Database (Denmark)

Profirovic, Jasmina; Vardya, Irina; Voyno-Yasenetskaya, Tatyana

2006-01-01

39 5-HYDROXYTRYPTAMINE 4 RECEPTOR IN THE ENDOTHELIAL CELLS. J. Profirovic, I. Vardya, T. Voyno-Yasenetskaya, Department of Pharmacology, University of Illinois at Chicago, Chicago, IL. Serotonin (5-hydroxytryptamine [5-HT]) is an important neurotransmitter that regulates multiple events in the ce......39 5-HYDROXYTRYPTAMINE 4 RECEPTOR IN THE ENDOTHELIAL CELLS. J. Profirovic, I. Vardya, T. Voyno-Yasenetskaya, Department of Pharmacology, University of Illinois at Chicago, Chicago, IL. Serotonin (5-hydroxytryptamine [5-HT]) is an important neurotransmitter that regulates multiple events...... gap formation in HUVECs. We are currently investigating the mechanism underlying 5-HT4 receptor-induced actin cytoskeleton changes in the endothelial cells. These data suggest that by activating 5-HT4 receptor, serotonin could be involved in regulation of actin cytoskeleton dynamics in the endothelial...

Neuroactive Steroids: Receptor Interactions and Responses

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Kald Beshir Tuem

2017-08-01

Full Text Available Neuroactive steroids (NASs are naturally occurring steroids, which are synthesized centrally as de novo from cholesterol and are classified as pregnane, androstane, and sulfated neurosteroids (NSs. NASs modulate many processes via interacting with gamma-aminobutyric acid (GABA, N-methyl-d-aspartate, serotonin, voltage-gated calcium channels, voltage-dependent anion channels, α-adrenoreceptors, X-receptors of the liver, transient receptor potential channels, microtubule-associated protein 2, neurotrophin nerve growth factor, and σ1 receptors. Among these, NSs (especially allopregnanolone have high potency and extensive GABA-A receptors and hence demonstrate anticonvulsant, anesthetic, central cytoprotectant, and baroreflex inhibitory effects. NSs are also involved in mood and learning via serotonin and anti-nociceptive activity via T-type voltage-gated Ca2+ channels. Moreover, they are modulators of mitochondrial function, synaptic plasticity, or regulators of apoptosis, which have a role in neuroprotective via voltage-dependent anion channels receptors. For proper functioning, NASs need to be in their normal level, whereas excess and deficiency may lead to abnormalities. When they are below the normal, NSs could have a part in development of depression, neuro-inflammation, multiple sclerosis, experimental autoimmune encephalitis, epilepsy, and schizophrenia. On the other hand, stress and attention deficit disorder could occur during excessive level. Overall, NASs are very important molecules with major neuropsychiatric activity.

Methylphenidate enhances NMDA-receptor response in medial prefrontal cortex via sigma-1 receptor: a novel mechanism for methylphenidate action.

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Chun-Lei Zhang

Full Text Available Methylphenidate (MPH, commercially called Ritalin or Concerta, has been widely used as a drug for Attention Deficit Hyperactivity Disorder (ADHD. Noteworthily, growing numbers of young people using prescribed MPH improperly for pleasurable enhancement, take high risk of addiction. Thus, understanding the mechanism underlying high level of MPH action in the brain becomes an important goal nowadays. As a blocker of catecholamine transporters, its therapeutic effect is explained as being due to proper modulation of D1 and α2A receptor. Here we showed that higher dose of MPH facilitates NMDA-receptor mediated synaptic transmission via a catecholamine-independent mechanism, in layer V∼VI pyramidal cells of the rat medial prefrontal cortex (PFC. To indicate its postsynaptic action, we next found that MPH facilitates NMDA-induced current and such facilitation could be blocked by σ1 but not D1/5 and α2 receptor antagonists. And this MPH eliciting enhancement of NMDA-receptor activity involves PLC, PKC and IP3 receptor mediated intracellular Ca(2+ increase, but does not require PKA and extracellular Ca(2+ influx. Our additional pharmacological studies confirmed that higher dose of MPH increases locomotor activity via interacting with σ1 receptor. Together, the present study demonstrates for the first time that MPH facilitates NMDA-receptor mediated synaptic transmission via σ1 receptor, and such facilitation requires PLC/IP3/PKC signaling pathway. This novel mechanism possibly explains the underlying mechanism for MPH induced addictive potential and other psychiatric side effects.

Structural–Functional Features of the Thyrotropin Receptor: A Class A G-Protein-Coupled Receptor at Work

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Gerd Krause

2017-04-01

Full Text Available The thyroid-stimulating hormone receptor (TSHR is a member of the glycoprotein hormone receptors, a sub-group of class A G-protein-coupled receptors (GPCRs. TSHR and its endogenous ligand thyrotropin (TSH are of essential importance for growth and function of the thyroid gland and proper function of the TSH/TSHR system is pivotal for production and release of thyroid hormones. This receptor is also important with respect to pathophysiology, such as autoimmune (including ophthalmopathy or non-autoimmune thyroid dysfunctions and cancer development. Pharmacological interventions directly targeting the TSHR should provide benefits to disease treatment compared to currently available therapies of dysfunctions associated with the TSHR or the thyroid gland. Upon TSHR activation, the molecular events conveying conformational changes from the extra- to the intracellular side of the cell across the membrane comprise reception, conversion, and amplification of the signal. These steps are highly dependent on structural features of this receptor and its intermolecular interaction partners, e.g., TSH, antibodies, small molecules, G-proteins, or arrestin. For better understanding of signal transduction, pathogenic mechanisms such as autoantibody action and mutational modifications or for developing new pharmacological strategies, it is essential to combine available structural data with functional information to generate homology models of the entire receptor. Although so far these insights are fragmental, in the past few decades essential contributions have been made to investigate in-depth the involved determinants, such as by structure determination via X-ray crystallography. This review summarizes available knowledge (as of December 2016 concerning the TSHR protein structure, associated functional aspects, and based on these insights we suggest several receptor complex models. Moreover, distinct TSHR properties will be highlighted in comparison to other

Structural-Functional Features of the Thyrotropin Receptor: A Class A G-Protein-Coupled Receptor at Work.

Science.gov (United States)

Kleinau, Gunnar; Worth, Catherine L; Kreuchwig, Annika; Biebermann, Heike; Marcinkowski, Patrick; Scheerer, Patrick; Krause, Gerd

2017-01-01

The thyroid-stimulating hormone receptor (TSHR) is a member of the glycoprotein hormone receptors, a sub-group of class A G-protein-coupled receptors (GPCRs). TSHR and its endogenous ligand thyrotropin (TSH) are of essential importance for growth and function of the thyroid gland and proper function of the TSH/TSHR system is pivotal for production and release of thyroid hormones. This receptor is also important with respect to pathophysiology, such as autoimmune (including ophthalmopathy) or non-autoimmune thyroid dysfunctions and cancer development. Pharmacological interventions directly targeting the TSHR should provide benefits to disease treatment compared to currently available therapies of dysfunctions associated with the TSHR or the thyroid gland. Upon TSHR activation, the molecular events conveying conformational changes from the extra- to the intracellular side of the cell across the membrane comprise reception, conversion, and amplification of the signal. These steps are highly dependent on structural features of this receptor and its intermolecular interaction partners, e.g., TSH, antibodies, small molecules, G-proteins, or arrestin. For better understanding of signal transduction, pathogenic mechanisms such as autoantibody action and mutational modifications or for developing new pharmacological strategies, it is essential to combine available structural data with functional information to generate homology models of the entire receptor. Although so far these insights are fragmental, in the past few decades essential contributions have been made to investigate in-depth the involved determinants, such as by structure determination via X-ray crystallography. This review summarizes available knowledge (as of December 2016) concerning the TSHR protein structure, associated functional aspects, and based on these insights we suggest several receptor complex models. Moreover, distinct TSHR properties will be highlighted in comparison to other class A GPCRs to

Structural–Functional Features of the Thyrotropin Receptor: A Class A G-Protein-Coupled Receptor at Work

Science.gov (United States)

Kleinau, Gunnar; Worth, Catherine L.; Kreuchwig, Annika; Biebermann, Heike; Marcinkowski, Patrick; Scheerer, Patrick; Krause, Gerd

2017-01-01

The thyroid-stimulating hormone receptor (TSHR) is a member of the glycoprotein hormone receptors, a sub-group of class A G-protein-coupled receptors (GPCRs). TSHR and its endogenous ligand thyrotropin (TSH) are of essential importance for growth and function of the thyroid gland and proper function of the TSH/TSHR system is pivotal for production and release of thyroid hormones. This receptor is also important with respect to pathophysiology, such as autoimmune (including ophthalmopathy) or non-autoimmune thyroid dysfunctions and cancer development. Pharmacological interventions directly targeting the TSHR should provide benefits to disease treatment compared to currently available therapies of dysfunctions associated with the TSHR or the thyroid gland. Upon TSHR activation, the molecular events conveying conformational changes from the extra- to the intracellular side of the cell across the membrane comprise reception, conversion, and amplification of the signal. These steps are highly dependent on structural features of this receptor and its intermolecular interaction partners, e.g., TSH, antibodies, small molecules, G-proteins, or arrestin. For better understanding of signal transduction, pathogenic mechanisms such as autoantibody action and mutational modifications or for developing new pharmacological strategies, it is essential to combine available structural data with functional information to generate homology models of the entire receptor. Although so far these insights are fragmental, in the past few decades essential contributions have been made to investigate in-depth the involved determinants, such as by structure determination via X-ray crystallography. This review summarizes available knowledge (as of December 2016) concerning the TSHR protein structure, associated functional aspects, and based on these insights we suggest several receptor complex models. Moreover, distinct TSHR properties will be highlighted in comparison to other class A GPCRs to

Cocaine Inhibits Dopamine D2 Receptor Signaling via Sigma-1-D2 Receptor Heteromers

Science.gov (United States)

Navarro, Gemma; Moreno, Estefania; Bonaventura, Jordi; Brugarolas, Marc; Farré, Daniel; Aguinaga, David; Mallol, Josefa; Cortés, Antoni; Casadó, Vicent; Lluís, Carmen; Ferre, Sergi

2013-01-01

Under normal conditions the brain maintains a delicate balance between inputs of reward seeking controlled by neurons containing the D1-like family of dopamine receptors and inputs of aversion coming from neurons containing the D2-like family of dopamine receptors. Cocaine is able to subvert these balanced inputs by altering the cell signaling of these two pathways such that D1 reward seeking pathway dominates. Here, we provide an explanation at the cellular and biochemical level how cocaine may achieve this. Exploring the effect of cocaine on dopamine D2 receptors function, we present evidence of σ1 receptor molecular and functional interaction with dopamine D2 receptors. Using biophysical, biochemical, and cell biology approaches, we discovered that D2 receptors (the long isoform of the D2 receptor) can complex with σ1 receptors, a result that is specific to D2 receptors, as D3 and D4 receptors did not form heteromers. We demonstrate that the σ1-D2 receptor heteromers consist of higher order oligomers, are found in mouse striatum and that cocaine, by binding to σ1 -D2 receptor heteromers, inhibits downstream signaling in both cultured cells and in mouse striatum. In contrast, in striatum from σ1 knockout animals these complexes are not found and this inhibition is not seen. Taken together, these data illuminate the mechanism by which the initial exposure to cocaine can inhibit signaling via D2 receptor containing neurons, destabilizing the delicate signaling balance influencing drug seeking that emanates from the D1 and D2 receptor containing neurons in the brain. PMID:23637801

Mediator and p300/CBP-Steroid Receptor Coactivator Complexes Have Distinct Roles, but Function Synergistically, during Estrogen Receptor α-Dependent Transcription with Chromatin Templates

OpenAIRE

Acevedo, Mari Luz; Kraus, W. Lee

2003-01-01

Ligand-dependent transcriptional activation by nuclear receptors involves the recruitment of various coactivators to the promoters of hormone-regulated genes assembled into chromatin. Nuclear receptor coactivators include histone acetyltransferase complexes, such as p300/CBP-steroid receptor coactivator (SRC), as well as the multisubunit mediator complexes (“Mediator”), which may help recruit RNA polymerase II to the promoter. We have used a biochemical approach, including an in vitro chromat...

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.

Prostaglandin Receptor Signaling in Disease

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Toshiyuki Matsuoka

2007-01-01

Full Text Available Prostanoids, consisting of the prostaglandins (PGs and the thromboxanes (TXs, are a group of lipid mediators formed in response to various stimuli. They include PGD2, PGE2, PGF2α, PGI2, and TXA2. They are released outside of the cells immediately after synthesis, and exert their actions by binding to a G-protein coupled rhodopsin-type receptor on the surface of target cells. There are eight types of the prostanoid receptors conserved in mammals from mouse to human. They are the PGD receptor (DP, four subtypes of the PGE receptor (EP1, EP2, EP3, and EP4, the PGF receptor (FP, PGI receptor (IP, and TXA receptor (TP. Recently, mice deficient in each of these prostanoid receptors were generated and subjected to various experimental models of disease. These studies have revealed the roles of PG receptor signaling in various pathological conditions, and suggest that selective manipulation of the prostanoid receptors may be beneficial in treatment of the pathological conditions. Here we review these recent findings of roles of prostanoid receptor signaling and their therapeutic implications.

Receptor Autoradiography Protocol for the Localized Visualization of Angiotensin II Receptors.

Science.gov (United States)

Linares, Andrea; Couling, Leena E; Carrera, Eduardo J; Speth, Robert C

2016-06-07

This protocol describes receptor binding patterns for Angiotensin II (Ang II) in the rat brain using a radioligand specific for Ang II receptors to perform receptor autoradiographic mapping. Tissue specimens are harvested and stored at -80 °C. A cryostat is used to coronally section the tissue (brain) and thaw-mount the sections onto charged slides. The slide-mounted tissue sections are incubated in (125)I-SI-Ang II to radiolabel Ang II receptors. Adjacent slides are separated into two sets: 'non-specific binding' (NSP) in the presence of a receptor saturating concentration of non-radiolabeled Ang II, or an AT1 Ang II receptor subtype (AT1R) selective Ang II receptor antagonist, and 'total binding' with no AT1R antagonist. A saturating concentration of AT2 Ang II receptor subtype (AT2R) antagonist (PD123319, 10 µM) is also present in the incubation buffer to limit (125)I-SI-Ang II binding to the AT1R subtype. During a 30 min pre-incubation at ~22 °C, NSP slides are exposed to 10 µM PD123319 and losartan, while 'total binding' slides are exposed to 10 µM PD123319. Slides are then incubated with (125)I-SI-Ang II in the presence of PD123319 for 'total binding', and PD123319 and losartan for NSP in assay buffer, followed by several 'washes' in buffer, and water to remove salt and non-specifically bound radioligand. The slides are dried using blow-dryers, then exposed to autoradiography film using a specialized film and cassette. The film is developed and the images are scanned into a computer for visual and quantitative densitometry using a proprietary imaging system and a spreadsheet. An additional set of slides are thionin-stained for histological comparisons. The advantage of using receptor autoradiography is the ability to visualize Ang II receptors in situ, within a section of a tissue specimen, and anatomically identify the region of the tissue by comparing it to an adjacent histological reference section.

Ionotropic and Metabotropic Proton-Sensing Receptors Involved in Airway Inflammation in Allergic Asthma

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Haruka Aoki

2014-01-01

Full Text Available An acidic microenvironment has been shown to evoke a variety of airway responses, including cough, bronchoconstriction, airway hyperresponsiveness (AHR, infiltration of inflammatory cells in the lung, and stimulation of mucus hyperproduction. Except for the participation of transient receptor potential vanilloid-1 (TRPV1 and acid-sensing ion channels (ASICs in severe acidic pH (of less than 6.0-induced cough and bronchoconstriction through sensory neurons, the molecular mechanisms underlying extracellular acidic pH-induced actions in the airways have not been fully understood. Recent studies have revealed that ovarian cancer G protein-coupled receptor 1 (OGR1-family G protein-coupled receptors, which sense pH of more than 6.0, are expressed in structural cells, such as airway smooth muscle cells and epithelial cells, and in inflammatory and immune cells, such as eosinophils and dendritic cells. They function in a variety of airway responses related to the pathophysiology of inflammatory diseases, including allergic asthma. In the present review, we discuss the roles of ionotropic TRPV1 and ASICs and metabotropic OGR1-family G protein-coupled receptors in the airway inflammation and AHR in asthma and respiratory diseases.

Expression of GABAergic receptors in mouse taste receptor cells.

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Margaret R Starostik

Full Text Available BACKGROUND: Multiple excitatory neurotransmitters have been identified in the mammalian taste transduction, with few studies focused on inhibitory neurotransmitters. Since the synthetic enzyme glutamate decarboxylase (GAD for gamma-aminobutyric acid (GABA is expressed in a subset of mouse taste cells, we hypothesized that other components of the GABA signaling pathway are likely expressed in this system. GABA signaling is initiated by the activation of either ionotropic receptors (GABA(A and GABA(C or metabotropic receptors (GABA(B while it is terminated by the re-uptake of GABA through transporters (GATs. METHODOLOGY/PRINCIPAL FINDINGS: Using reverse transcriptase-PCR (RT-PCR analysis, we investigated the expression of different GABA signaling molecules in the mouse taste system. Taste receptor cells (TRCs in the circumvallate papillae express multiple subunits of the GABA(A and GABA(B receptors as well as multiple GATs. Immunocytochemical analyses examined the distribution of the GABA machinery in the circumvallate papillae. Both GABA(A-and GABA(B- immunoreactivity were detected in the peripheral taste receptor cells. We also used transgenic mice that express green fluorescent protein (GFP in either the Type II taste cells, which can respond to bitter, sweet or umami taste stimuli, or in the Type III GAD67 expressing taste cells. Thus, we were able to identify that GABAergic receptors are expressed in some Type II and Type III taste cells. Mouse GAT4 labeling was concentrated in the cells surrounding the taste buds with a few positively labeled TRCs at the margins of the taste buds. CONCLUSIONS/SIGNIFICANCE: The presence of GABAergic receptors localized on Type II and Type III taste cells suggests that GABA is likely modulating evoked taste responses in the mouse taste bud.

G-protein coupling of cannabinoid receptors

International Nuclear Information System (INIS)

Glass, M.

2001-01-01

Full text: Since the cloning of the cannabinoid CB1 and CB2 receptors in the early 1990's extensive research has focused on understanding their signal transduction pathways. While it has been known for sometime that both receptors can couple to intracellular signalling via pertussis toxin sensitive G-proteins (Gi/Go), the specificity and kinetics of these interactions have only recently been elucidated. We have developed an in situ reconstitution approach to investigating receptor-G-protein interactions. This approach involves chaotropic extraction of receptor containing membranes in order to inactivate or remove endogenous G-proteins. Recombinant or isolated brain G-proteins can then be added back to the receptors, and their activation monitored through the binding of [ 35 S]-GTPγS. This technique has been utilised for an extensive study of cannabinoid receptor mediated activation of G-proteins. In these studies we have established that CB1 couples with high affinity to both Gi and Go type G-proteins. In contrast, CB2 couples strongly to Gi, but has a very low affinity for Go. This finding correlated well with the previous findings that while CB1 and CB2 both couple to the inhibition of adenylate cyclase, CB1 but not CB2 could also inhibit calcium channels. We then examined the ability of a range of cannabinoid agonists to activate the Gi and Go via CB1. Conventional receptor theory suggests that a receptor is either active or inactive with regard to a G-protein and that the active receptor activates all relevant G-proteins equally. However, in this study we found that agonists could produce different degrees of activation, depending on which G-protein was present. Further studies have compared the ability of the two endocannabinoids to drive the activation of Gi or Go. These studies show that agonists can induce multiple forms of activated receptor that differ in their ability to catalyse the activation of Gi or Go. The ability of an agonist to drive a receptor

Assessment of endocrine disruption potential of essential oils of culinary herbs and spices involving glucocorticoid, androgen and vitamin D receptors.

Science.gov (United States)

Bartoňková, Iveta; Dvořák, Zdeněk

2018-04-25

Essential oils (EOs) of culinary herbs and spices are consumed on a daily basis. They are multicomponent mixtures of compounds with already demonstrated biological activities. Taking into account regular dietary intake and the chemical composition of EOs, they may be considered as candidates for endocrine-disrupting entities. Therefore, we examined the effects of 31 EOs of culinary herbs and spices on transcriptional activities of glucocorticoid receptor (GR), androgen receptor (AR) and vitamin D receptor (VDR). Using reporter gene assays in stably transfected cell lines, weak anti-androgen and anti-glucocorticoid activity was observed for EO of vanilla and nutmeg, respectively. Moderate augmentation of calcitriol-dependent VDR activity was caused by EOs of ginger, thyme, coriander and lemongrass. Mixed anti-glucocorticoid and VDR-stimulatory activities were displayed by EOs of turmeric, oregano, dill, caraway, verveine and spearmint. The remaining 19 EOs were inactive against all receptors under investigation. Analyses of GR, AR and VDR target genes by means of RT-PCR confirmed the VDR-stimulatory effects, but could not confirm the anti-glucocorticoid and anti-androgen effects of EOs. In conclusion, although we observed minor effects of several EOs on transcriptional activities of GR, AR and VDR, the toxicological significance of these effects is very low. Hence, 31 EOs of culinary herbs and spices may be considered safe, in terms of endocrine disruption involving receptors GR, AR and VDR.

Gonadal cell surface receptor for plasma retinol-binding protein

International Nuclear Information System (INIS)

Krishna Bhat, M.; Cama, H.R.

1979-01-01

A specific membrane receptor for plasma retinol-binding protein has been demonstrated in testicular cells. Prealbumin-2 did not show any specific binding to the membrane. The affinity of retinol-binding protein for receptor drastically decreases upon delivery of retinol and the retinol-binding protein does not enter the cell. The mechanism of delivery of retinol to the target cell by plasma retinol-binding protein has been investigated. The process involves two steps; direct binding of retinol-binding protein to the receptor and uptake of retinol by the target cell with a concomitant drastic reduction in the affinity of the retinol-binding protein to the receptor. Probably the second step of the process needs a cytosolic factor, possibly the cellular retinol-binding protein or an enzyme. The binding of retinol-binding protein to the receptor is saturable and reversible. The interaction shows a Ksub(d) value of 2.1x10 -10 . The specific binding of a retinol-binding protein with great affinity has been employed in the development of a method for radioassay of the receptor. The receptor level of the gonadal cell has been found to vary with the stage of differentiation. The receptor concentrations in 11-week-old birds and adult birds are comparable. Testosterone treatment of 11-week-old birds produced a substantial increase in the receptor concentration over control, while the protein content increased marginally, indicating that, probably, synthesis of the receptor is specifcally induced by testosterone during spermatogenesis, and the concentration of receptor is relatively higher before the formation of the acrosome. (Auth.)

N-glycosylation of the β2 adrenergic receptor regulates receptor function by modulating dimerization.

Science.gov (United States)

Li, Xiaona; Zhou, Mang; Huang, Wei; Yang, Huaiyu

2017-07-01

N-glycosylation is a common post-translational modification of G-protein-coupled receptors (GPCRs). However, it remains unknown how N-glycosylation affects GPCR signaling. β 2 adrenergic receptor (β 2 AR) has three N-glycosylation sites: Asn6, Asn15 at the N-terminus, and Asn187 at the second extracellular loop (ECL2). Here, we show that deletion of the N-glycan did not affect receptor expression and ligand binding. Deletion of the N-glycan at the N-terminus rather than Asn187 showed decreased effects on isoproterenol-promoted G-protein-dependent signaling, β-arrestin2 recruitment, and receptor internalization. Both N6Q and N15Q showed decreased receptor dimerization, while N187Q did not influence receptor dimerization. As decreased β 2 AR homodimer accompanied with reduced efficiency for receptor function, we proposed that the N-glycosylation of β 2 AR regulated receptor function by influencing receptor dimerization. To verify this hypothesis, we further paid attention to the residues at the dimerization interface. Studies of Lys60 and Glu338, two residues at the receptor dimerization interface, exhibited that the K60A/E338A showed decreased β 2 AR dimerization and its effects on receptor signaling were similar to N6Q and N15Q, which further supported the importance of receptor dimerization for receptor function. This work provides new insights into the relationship among glycosylation, dimerization, and function of GPCRs. Peptide-N-glycosidase F (PNGase F, EC 3.2.2.11); endo-β-N-acetylglucosaminidase A (Endo-A, EC 3.2.1.96). © 2017 Federation of European Biochemical Societies.

Prognostic Value of Estrogen Receptor alpha and Progesterone Receptor Conversion in Distant Breast Cancer Metastases

NARCIS (Netherlands)

Hoefnagel, Laurien D. C.; Moelans, Cathy B.; Meijer, S. L.; van Slooten, Henk-Jan; Wesseling, Pieter; Wesseling, Jelle; Westenend, Pieter J.; Bart, Joost; Seldenrijk, Cornelis A.; Nagtegaal, Iris D.; Oudejans, Joost; van der Valk, Paul; van Gils, Carla H.; van der Wall, Elsken; van Diest, Paul J.

2012-01-01

BACKGROUND: Changes in the receptor profile of primary breast cancers to their metastases (receptor conversion) have been described for the estrogen receptor alpha (ER alpha) and progesterone receptor (PR). The purpose of this study was to evaluate the impact of receptor conversion for ER alpha and

(Pro)renin receptor: Involvement in diabetic retinopathy and development of molecular targeted therapy.

Science.gov (United States)

Kanda, Atsuhiro; Ishida, Susumu

2018-03-25

The renin-angiotensin system (RAS), a crucial regulator of systemic blood pressure (circulatory RAS), plays distinct roles in pathological angiogenesis and inflammation in various organs (tissue RAS), such as diabetic microvascular complications. Using ocular clinical samples and animal disease models, we elucidated molecular mechanisms in which tissue RAS excites the expression of vascular endothelial growth factor (VEGF)-A responsible for retinal inflammation and angiogenesis, the two major pathological events in diabetic retinopathy (DR). Furthermore, we showed the involvement of (pro)renin receptor [(P)RR] in retinal RAS activation and its concurrent intracellular signal transduction (e.g., extracellular signal-regulated kinase); namely, the (P)RR-induced dual pathogenic bioactivity referred to as the receptor-associated prorenin system. Indeed, neovascular endothelial cells in the fibrovascular tissue collected from eyes with proliferative DR were immunoreactive for the receptor-associated prorenin system components including prorenin, (P)RR, phosphorylated extracellular signal-regulated kinase and VEGF-A. Protein levels of soluble (P)RR increased with its positive correlations with prorenin, renin enzymatic activity and VEGF in the vitreous of proliferative DR eyes, suggesting a close link between (P)RR and VEGF-A-driven angiogenic activity. Furthermore, we revealed an unsuspected, PAPS-independent role of (P)RR in glucose-induced oxidative stress. Recently, we developed an innovative single-strand ribonucleic acid interference molecule selectively targeting human and mouse (P)RR, and confirmed its efficacy in suppressing diabetes-induced retinal inflammation in mice. Our data using clinical samples and animal models suggested the significant implication of (P)RR in the pathogenesis of DR, and the potential usefulness of the ribonucleic acid interference molecule as a therapeutic agent to attenuate ocular inflammation and angiogenesis. © 2018 The Authors

[A study on toxic effects of sodium salicylate on rat cochlear spiral ganglion neurons: dopamine receptors mediate expressions of NMDA and GABAA receptors].

Science.gov (United States)

Wei, Ting-Jia; Chen, Hui-Ying; Huang, Xi; Weng, Jing-Jin; Qin, Jiang-Yuan; Su, Ji-Ping

2017-06-25

The aim of the present study was to observe whether dopamine receptor (DR) was involved in the effects of sodium salicylate (SS) on the expressions of N-methyl-D-aspartic acid (NMDA) and γ-aminobutyric acid (GABA) receptors in rat cochlear spiral ganglion neurons (SGNs). Forty-eight hours after primary culture of rat SGNs, immunofluorescence technique was applied to detect expressions of DR1 and DR2, the two subtypes of dopamine receptors. Western blot was performed to assess NMDA receptor NR1 subunit and GABA A receptor subunit α2 (GABRα2) protein expressions in the SGNs after the treatments of SS alone or in combination with DR antagonists. The results demonstrated that: (1) The DR1 and DR2 were expressed in the bodies and axons of the SGN; (2) After the treatment with SS, the surface protein expressions of GABRα2 and NR1 were decreased by 44.69% and 21.57%, respectively, while the total protein expressions showed no significant changes; (3) Neither SS + SCH23390 (DR1 antagonist) group nor SS + Eticlopride (DR2 antagonist) group showed significant differences in GABRα2 and NR1 surface protein expressions compared with the control group. These results suggest that SS regulates the surface GABA A and NMDA receptors trafficking on SGN, and the mechanism may involve DR mediation.

Waking action of ursodeoxycholic acid (UDCA involves histamine and GABAA receptor block.

Directory of Open Access Journals (Sweden)

Yevgenij Yanovsky

Full Text Available Since ancient times ursodeoxycholic acid (UDCA, a constituent of bile, is used against gallstone formation and cholestasis. A neuroprotective action of UDCA was demonstrated recently in models of Alzheimer's disease and retinal degeneration. The mechanisms of UDCA action in the nervous system are poorly understood. We show now that UDCA promotes wakefulness during the active period of the day, lacking this activity in histamine-deficient mice. In cultured hypothalamic neurons UDCA did not affect firing rate but synchronized the firing, an effect abolished by the GABA(AR antagonist gabazine. In histaminergic neurons recorded in slices UDCA reduced amplitude and duration of spontaneous and evoked IPSCs. In acutely isolated histaminergic neurons UDCA inhibited GABA-evoked currents and sIPSCs starting at 10 µM (IC(50 = 70 µM and did not affect NMDA- and AMPA-receptor mediated currents at 100 µM. Recombinant GABA(A receptors composed of α1, β1-3 and γ2L subunits expressed in HEK293 cells displayed a sensitivity to UDCA similar to that of native GABA(A receptors. The mutation α1V256S, known to reduce the inhibitory action of pregnenolone sulphate, reduced the potency of UDCA. The mutation α1Q241L, which abolishes GABA(AR potentiation by several neurosteroids, had no effect on GABA(AR inhibition by UDCA. In conclusion, UDCA enhances alertness through disinhibition, at least partially of the histaminergic system via GABA(A receptors.

Microarray-Based Determination of Estrogen Receptor, Progesterone Receptor, and HER2 Receptor Status in Breast Cancer

NARCIS (Netherlands)

Roepman, Paul; Horlings, Hugo M.; Krijgsman, Oscar; Kok, Marleen; Bueno-de-Mesquita, Jolien M.; Bender, Richard; Linn, Sabine C.; Glas, Annuska M.; van de Vijver, Marc J.

2009-01-01

Purpose: The level of estrogen receptor (ER), progesterone receptor (PR), and HER2 aids in the determination of prognosis and treatment of breast cancer. Immunohistochemistry is currently the predominant method for assessment, but differences in methods and interpretation can substantially affect

D2-like receptors in the descending dopaminergic pathway are not involved in the decreased postoperative nociceptive threshold induced by plantar incision in adult rats

Directory of Open Access Journals (Sweden)

Ohtani N

2016-10-01

Full Text Available Norimasa Ohtani, Eiji Masaki Division of Dento-oral Anesthesiology, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan Background: Approximately half of all patients who undergo surgery develop postoperative pain, the mechanisms of which are not well understood by anesthesiologists. D2-like receptors in the descending dopaminergic pathway play an important role in regulation of pain transmission in the spinal cord. Impairment of inhibitory neurons in the spinal cord is suggested as part of the mechanism for neuropathic pain, which is one component of postoperative pain. The purpose of this study was to investigate whether impairment of D2-like receptors in the descending dopaminergic pathway in the spinal cord is involved in the decreased postoperative nociceptive threshold in rats.Methods: Male Sprague-Dawley rats (250–300 g were anesthetized with sevoflurane and an intrathecal (IT catheter was implanted. Six days later, a plantar incision was made. On the following day, saline, a D2-like receptor agonist (quinpirole, or a D2-like receptor antagonist (sulpiride was administered intrathecally. Thermal and mechanical nociceptive responses were assessed by exposure to infrared radiant heat and the von Frey filament test before and after plantar incision.Results: Plantar incision decreased both thermal latency and the mechanical nociceptive threshold. IT administration of quinpirole inhibited the nociceptive responses induced by plantar incision, but sulpiride had no effect.Conclusion: A D2-like receptor agonist had antinociceptive effects on the hypersensitivity response triggered by a surgical incision, but a D2-like receptor antagonist had no effect on this response. These results suggest that impairment and/or modification of D2-like receptors in the descending dopaminergic pathway in the spinal cord is not involved in the postoperative decrease in nociceptive threshold. Keywords: postoperative pain, descending pathway

Antidepressants inhibit P2X4 receptor function: a possible involvement in neuropathic pain relief

Directory of Open Access Journals (Sweden)

Tozaki-Saitoh Hidetoshi

2009-04-01

Full Text Available Abstract Background Neuropathic pain is characterized by pain hypersensitivity to innocuous stimuli (tactile allodynia that is nearly always resistant to known treatments such as non-steroidal anti-inflammatory drugs or even opioids. It has been reported that some antidepressants are effective for treating neuropathic pain. However, the underlying molecular mechanisms are not well understood. We have recently demonstrated that blocking P2X4 receptors in the spinal cord reverses tactile allodynia after peripheral nerve injury in rats, implying that P2X4 receptors are a key molecule in neuropathic pain. We investigated a possible role of antidepressants as inhibitors of P2X4 receptors and analysed their analgesic mechanism using an animal model of neuropathic pain. Results Antidepressants strongly inhibited ATP-mediated Ca2+ responses in P2X4 receptor-expressing 1321N1 cells, which are known to have no endogenous ATP receptors. Paroxetine exhibited the most powerful inhibition of calcium influx via rat and human P2X4 receptors, with IC50 values of 2.45 μM and 1.87 μM, respectively. Intrathecal administration of paroxetine produced a striking antiallodynic effect in an animal model of neuropathic pain. Co-administration of WAY100635, ketanserin or ondansetron with paroxetine induced no significant change in the antiallodynic effect of paroxetine. Furthermore, the antiallodynic effect of paroxetine was observed even in rats that had received intrathecal pretreatment with 5,7-dihydroxytryptamine, which dramatically depletes spinal 5-hydroxytryptamine. Conclusion These results suggest that paroxetine acts as a potent analgesic in the spinal cord via a mechanism independent of its inhibitory effect on serotonin transporters. Powerful inhibition on P2X4 receptors may underlie the analgesic effect of paroxetine, and it is possible that some antidepressants clinically used in patients with neuropathic pain show antiallodynic effects, at least in part

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.

Contributions to the study of the role of IFN gamma and its receptor on the physiopathology of disorders involving the immune system

International Nuclear Information System (INIS)

Bello, Iraldo; Lopez, Pedro; Torres, Yeny; Bermudez, Cimara

2007-01-01

Interferon gamma (IFNγ) is a Th1-type cytokine. The study of the IFNγ system and its receptor is essential for increasing the efficacy of this drug for clinical settings. Here we describe the role of IFNγ and its receptor on the physiopathology of disorders involving the immune system. Several molecular forms of IFNGR1, from 84 to 13kDa, and soluble receptor (60-67 kDa) with the capacity to bind IFNγ arising from proteolytic processing events are shown. These forms bind IFNγ. A new type of interaction between the IFNα and IFNγ receptors that depends on the presence of IFNα is also described. There are high levels of soluble IFNGR1 in the plasma of rheumatoid arthritis (RA) patients. The role of IFNγ as a negative modulator for CCR-4, a chemokine receptor up-regulated significantly in juvenile rheumatoid arthritis (JRA) patients, is described. A recombinant anti-IL-2-IFNγ antagonist was developed. This molecule inhibits the biological actions of IL-2 and IFNγ, turning this protein into a Th1 antagonist (AnTh1) potentially useful for the treatment of autoimmune disorders. (Author)

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.

Soman- or kainic acid-induced convulsions decrease muscarinic receptors but not benzodiazepine receptors

International Nuclear Information System (INIS)

Churchill, L.; Pazdernik, T.L.; Cross, R.S.; Nelson, S.R.; Samson, F.E.

1990-01-01

[3H]Quinuclidinyl benzilate (QNB) binding to muscarinic receptors decreased in the rat forebrain after convulsions induced by a single dose of either soman, a potent inhibitor of acetylcholinesterase, or kainic acid, an excitotoxin. A Rosenthal plot revealed that the receptors decreased in number rather than affinity. When the soman-induced convulsions were blocked, the decrease in muscarinic receptors at 3 days was less extensive than when convulsions occurred and at 10 days they approached control levels in most of the brain areas. The most prominent decrements in QNB binding were in the piriform cortex where the decline in QNB binding is probably related to the extensive convulsion-associated neuropathology. The decrements in QNB binding after convulsions suggest that the convulsive state leads to a down-regulation of muscarinic receptors in some brain areas. In contrast to the decrease in QNB binding after convulsions, [3H]flunitrazepam binding to benzodiazepine receptors did not change even in the piriform cortex where the loss in muscarinic receptors was most prominent. Thus, it appears that those neuronal processes that bear muscarinic receptors are more vulnerable to convulsion-induced change than those with benzodiazepine receptors

β-Adrenergic Receptor Mediation of Stress-Induced Reinstatement of Extinguished Cocaine-Induced Conditioned Place Preference in Mice: Roles for β1 and β2 Adrenergic Receptors

Science.gov (United States)

Vranjkovic, Oliver; Hang, Shona; Baker, David A.

2012-01-01

Stress can trigger the relapse of drug use in recovering cocaine addicts and reinstatement in rodent models through mechanisms that may involve norepinephrine release and β-adrenergic receptor activation. The present study examined the role of β-adrenergic receptor subtypes in the stressor-induced reinstatement of extinguished cocaine-induced (15 mg/kg i.p.) conditioned place preference in mice. Forced swim (6 min at 22°C) stress or activation of central noradrenergic neurotransmission by administration of the selective α2 adrenergic receptor antagonist 2-[(4,5-dihydro-1H-imidazol-2-yl)methyl]-2,3-dihydro-1-methyl-1H-isoindole (BRL-44,408) (10 mg/kg i.p.) induced reinstatement in wild-type, but not β- adrenergic receptor-deficient Adrb1/Adrb2 double-knockout, mice. In contrast, cocaine administration (15 mg/kg i.p.) resulted in reinstatement in both wild-type and β-adrenergic receptor knockout mice. Stress-induced reinstatement probably involved β2 adrenergic receptors. The β2 adrenergic receptor antagonist -(isopropylamino)-1-[(7-methyl-4-indanyl)oxy]butan-2-ol (ICI-118,551) (1 or 2 mg/kg i.p.) blocked reinstatement by forced swim or BRL-44,408, whereas administration of the nonselective β-adrenergic receptor agonist isoproterenol (2 or 4 mg/kg i.p.) or the β2 adrenergic receptor-selective agonist clenbuterol (2 or 4 mg/kg i.p.) induced reinstatement. Forced swim-induced, but not BRL-44,408-induced, reinstatement was also blocked by a high (20 mg/kg) but not low (10 mg/kg) dose of the β1 adrenergic receptor antagonist betaxolol, and isoproterenol-induced reinstatement was blocked by pretreatment with either ICI-118,551 or betaxolol, suggesting a potential cooperative role for β1 and β2 adrenergic receptors in stress-induced reinstatement. Overall, these findings suggest that targeting β-adrenergic receptors may represent a promising pharmacotherapeutic strategy for preventing drug relapse, particularly in cocaine addicts whose drug use is stress

Involvement of the histamine H{sub 4} receptor in clozapine-induced hematopoietic toxicity: Vulnerability under granulocytic differentiation of HL-60 cells

Energy Technology Data Exchange (ETDEWEB)

Goto, Aya; Mouri, Akihiro; Nagai, Tomoko; Yoshimi, Akira; Ukigai, Mako; Tsubai, Tomomi; Hida, Hirotake [Division of Clinical Sciences and Neuropsychopharmacology, Faculty and Graduate School of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503 (Japan); Ozaki, Norio [Department of Psychiatry, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550 (Japan); Noda, Yukihiro, E-mail: ynoda@meijo-u.ac.jp [Division of Clinical Sciences and Neuropsychopharmacology, Faculty and Graduate School of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503 (Japan)

2016-09-01

Clozapine is an effective antipsychotic for treatment-resistant schizophrenia, but can cause fatal hematopoietic toxicity as agranulocytosis. To elucidate the mechanism of hematopoietic toxicity induced by clozapine, we developed an in vitro assay system using HL-60 cells, and investigated the effect on hematopoiesis. HL-60 cells were differentiated by all-trans retinoic acid (ATRA) into three states according to the following hematopoietic process: undifferentiated HL-60 cells, those undergoing granulocytic ATRA-differentiation, and ATRA-differentiated granulocytic cells. Hematopoietic toxicity was evaluated by analyzing cell survival, cell proliferation, granulocytic differentiation, apoptosis, and necrosis. In undifferentiated HL-60 cells and ATRA-differentiated granulocytic cells, both clozapine (50 and 100 μM) and doxorubicin (0.2 µM) decreased the cell survival rate, but olanzapine (1–100 µM) did not. Under granulocytic differentiation for 5 days, clozapine, even at a concentration of 25 μM, decreased survival without affecting granulocytic differentiation, increased caspase activity, and caused apoptosis rather than necrosis. Histamine H{sub 4} receptor mRNA was expressed in HL-60 cells, whereas the expression decreased under granulocytic ATRA-differentiation little by little. Both thioperamide, a histamine H{sub 4} receptor antagonist, and DEVD-FMK, a caspase-3 inhibitor, exerted protection against clozapine-induced survival rate reduction, but not of live cell counts. 4-Methylhistamine, a histamine H{sub 4} receptor agonist, decreased the survival rate and live cell counts, as did clozapine. HL-60 cells under granulocytic differentiation are vulnerable under in vitro assay conditions to hematopoietic toxicity induced by clozapine. Histamine H{sub 4} receptor is involved in the development of clozapine-induced hematopoietic toxicity through apoptosis, and may be a potential target for preventing its occurrence through granulocytic differentiation

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...

The CCK(-like) receptor in the animal kingdom: functions, evolution and structures.

Science.gov (United States)

Staljanssens, Dorien; Azari, Elnaz Karimian; Christiaens, Olivier; Beaufays, Jérôme; Lins, Laurence; Van Camp, John; Smagghe, Guy

2011-03-01

In this review, the cholecystokinin (CCK)(-like) receptors throughout the animal kingdom are compared on the level of physiological functions, evolutionary basis and molecular structure. In vertebrates, the CCK receptor is an important member of the G-protein coupled receptors as it is involved in the regulation of many physiological functions like satiety, gastrointestinal motility, gastric acid secretion, gall bladder contraction, pancreatic secretion, panic, anxiety and memory and learning processes. A homolog for this receptor is also found in nematodes and arthropods, called CK receptor and sulfakinin (SK) receptor, respectively. These receptors seem to have evolved from a common ancestor which is probably still closely related to the nematode CK receptor. The SK receptor is more closely related to the CCK receptor and seems to have similar functions. A molecular 3D-model for the CCK receptor type 1 has been built together with the docking of the natural ligands for the CCK and SK receptors in the CCK receptor type 1. These molecular models can help to study ligand-receptor interactions, that can in turn be useful in the development of new CCK(-like) receptor agonists and antagonists with beneficial health effects in humans or potential for pest control. Copyright © 2010 Elsevier Inc. All rights reserved.

Cooperative ethylene receptor signaling

OpenAIRE

Liu, Qian; Wen, Chi-Kuang

2012-01-01

The gaseous plant hormone ethylene is perceived by a family of five ethylene receptor members in the dicotyledonous model plant Arabidopsis. Genetic and biochemical studies suggest that the ethylene response is suppressed by ethylene receptor complexes, but the biochemical nature of the receptor signal is unknown. Without appropriate biochemical measures to trace the ethylene receptor signal and quantify the signal strength, the biological significance of the modulation of ethylene responses ...

Profiling neurotransmitter receptor expression in the Ambystoma mexicanum brain.

Science.gov (United States)

Reyes-Ruiz, Jorge Mauricio; Limon, Agenor; Korn, Matthew J; Nakamura, Paul A; Shirkey, Nicole J; Wong, Jamie K; Miledi, Ricardo

2013-03-22

Ability to regenerate limbs and central nervous system (CNS) is unique to few vertebrates, most notably the axolotl (Ambystoma sp.). However, despite the fact the neurotransmitter receptors are involved in axonal regeneration, little is known regarding its expression profile. In this project, RT-PCR and qPCR were performed to gain insight into the neurotransmitter receptors present in Ambystoma. Its functional ability was studied by expressing axolotl receptors in Xenopus laevis oocytes by either injection of mRNA or by direct microtransplantation of brain membranes. Oocytes injected with axolotl mRNA expressed ionotropic receptors activated by GABA, aspartate+glycine and kainate, as well as metabotropic receptors activated by acetylcholine and glutamate. Interestingly, we did not see responses following the application of serotonin. Membranes from the axolotl brain were efficiently microtransplanted into Xenopus oocytes and two types of native GABA receptors that differed in the temporal course of their responses and affinities to GABA were observed. Results of this study are necessary for further characterization of axolotl neurotransmitter receptors and may be useful for guiding experiments aimed at understanding activity-dependant limb and CNS regeneration. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Radiolabelled GLP-1 receptor antagonist binds to GLP-1 receptor-expressing human tissues

International Nuclear Information System (INIS)

Waser, Beatrice; Reubi, Jean Claude

2014-01-01

Radiolabelled glucagon-like peptide 1 (GLP-1) receptor agonists have recently been shown to successfully image benign insulinomas in patients. For the somatostatin receptor targeting of tumours, however, it was recently reported that antagonist tracers were superior to agonist tracers. The present study therefore evaluated various forms of the 125 iodinated-Bolton-Hunter (BH)-exendin(9-39) antagonist tracer for the in vitro visualization of GLP-1 receptor-expressing tissues in rats and humans and compared it with the agonist tracer 125 I-GLP-1(7-36)amide. Receptor autoradiography studies with 125 I-GLP-1(7-36)amide agonist or 125 I-BH-exendin(9-39) antagonist radioligands were performed in human and rat tissues. The antagonist 125 I-BH-exendin(9-39) labelled at lysine 19 identifies all human and rat GLP-1 target tissues and GLP-1 receptor-expressing tumours. Binding is of high affinity and is comparable in all tested tissues in its binding properties with the agonist tracer 125 I-GLP-1(7-36)amide. For comparison, 125 I-BH-exendin(9-39) with the BH labelled at lysine 4 did identify the GLP-1 receptor in rat tissues but not in human tissues. The GLP-1 receptor antagonist exendin(9-39) labelled with 125 I-BH at lysine 19 is an excellent GLP-1 radioligand that identifies human and rat GLP-1 receptors in normal and tumoural tissues. It may therefore be the molecular basis to develop suitable GLP-1 receptor antagonist radioligands for in vivo imaging of GLP-1 receptor-expressing tissues in patients. (orig.)

Involvement of hippocampal NMDA receptors in encoding and consolidation, but not retrieval, processes of spontaneous object location memory in rats.

Science.gov (United States)

Yamada, Kazuo; Arai, Misaki; Suenaga, Toshiko; Ichitani, Yukio

2017-07-28

The hippocampus is thought to be involved in object location recognition memory, yet the contribution of hippocampal NMDA receptors to the memory processes, such as encoding, retention and retrieval, is unknown. First, we confirmed that hippocampal infusion of a competitive NMDA receptor antagonist, AP5 (2-amino-5-phosphonopentanoic acid, 20-40nmol), impaired performance of spontaneous object location recognition test but not that of novel object recognition test in Wistar rats. Next, the effects of hippocampal AP5 treatment on each process of object location recognition memory were examined with three different injection times using a 120min delay-interposed test: 15min before the sample phase (Time I), immediately after the sample phase (Time II), and 15min before the test phase (Time III). The blockade of hippocampal NMDA receptors before and immediately after the sample phase, but not before the test phase, markedly impaired performance of object location recognition test, suggesting that hippocampal NMDA receptors play an important role in encoding and consolidation/retention, but not retrieval, of spontaneous object location memory. Copyright © 2017 Elsevier B.V. All rights reserved.

Slow receptor dissociation kinetics differentiate macitentan from other endothelin receptor antagonists in pulmonary arterial smooth muscle cells.

Directory of Open Access Journals (Sweden)

John Gatfield

Full Text Available Two endothelin receptor antagonists (ERAs, bosentan and ambrisentan, are currently approved for the treatment of pulmonary arterial hypertension (PAH, a devastating disease involving an activated endothelin system and aberrant contraction and proliferation of pulmonary arterial smooth muscle cells (PASMC. The novel ERA macitentan has recently concluded testing in a Phase III morbidity/mortality clinical trial in PAH patients. Since the association and dissociation rates of G protein-coupled receptor antagonists can influence their pharmacological activity in vivo, we used human PASMC to characterize inhibitory potency and receptor inhibition kinetics of macitentan, ambrisentan and bosentan using calcium release and inositol-1-phosphate (IP(1 assays. In calcium release assays macitentan, ambrisentan and bosentan were highly potent ERAs with K(b values of 0.14 nM, 0.12 nM and 1.1 nM, respectively. Macitentan, but not ambrisentan and bosentan, displayed slow apparent receptor association kinetics as evidenced by increased antagonistic potency upon prolongation of antagonist pre-incubation times. In compound washout experiments, macitentan displayed a significantly lower receptor dissociation rate and longer receptor occupancy half-life (ROt(1/2 compared to bosentan and ambrisentan (ROt(1/2:17 minutes versus 70 seconds and 40 seconds, respectively. Because of its lower dissociation rate macitentan behaved as an insurmountable antagonist in calcium release and IP(1 assays, and unlike bosentan and ambrisentan it blocked endothelin receptor activation across a wide range of endothelin-1 (ET-1 concentrations. However, prolongation of the ET-1 stimulation time beyond ROt(1/2 rendered macitentan a surmountable antagonist, revealing its competitive binding mode. Bosentan and ambrisentan behaved as surmountable antagonists irrespective of the assay duration and they lacked inhibitory activity at high ET-1 concentrations. Thus, macitentan is a competitive

Effect of neoadjuvant chemotherapy on low-density lipoprotein (LDL) receptor and LDL receptor-related protein 1 (LRP-1) receptor in locally advanced breast cancer

International Nuclear Information System (INIS)

Pires, L.A.; Hegg, R.; Freitas, F.R.; Tavares, E.R.; Almeida, C.P.; Baracat, E.C.; Maranhão, R.C.

2012-01-01

Low-density lipoprotein (LDL) receptors are overexpressed in most neoplastic cell lines and provide a mechanism for the internalization and concentration of drug-laden nanoemulsions that bind to these receptors. The aim of the present study was to determine whether the administration of standard chemotherapeutic schemes can alter the expression of LDL and LDL receptor-related protein 1 (LRP-1) receptors in breast carcinoma. Fragments of tumoral and normal breast tissue from 16 consecutive volunteer women with breast cancer in stage II or III were obtained from biopsies before the beginning of neoadjuvant chemotherapy and after chemotherapy, from fragments excised during mastectomy. Tissues were analyzed by immunohistochemistry for both receptors. Because complete response to treatment was achieved in 4 patients, only the tumors from 12 were analyzed. Before chemotherapy, there was overexpression of LDL receptor in the tumoral tissue compared to normal breast tissue in 8 of these patients. LRP-1 receptor overexpression was observed in tumors of 4 patients. After chemotherapy, expression of both receptors decreased in the tumors of 6 patients, increased in 4 and was unchanged in 2. Nonetheless, even when chemotherapy reduced receptors expression, the expression was still above normal. The fact that chemotherapy does not impair LDL receptors expression supports the use of drug carrier systems that target neoplastic cells by the LDL receptor endocytic pathway in patients on conventional chemotherapy

Immunohistochemical Expression of Vitamin-D Receptor in Oral and ...

African Journals Online (AJOL)

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Receptor in Oral and Skin Squamous Cell Carcinoma of a Black African Subpopulation. *Corresponding Author ... Objective:The nuclear vitamin D receptor (VDR) is involved in multiple pathways that have a role to .... Figure1: Sections A (++) and B (+++) of OSCC showing nuclear positivity (red arrows) for malignant nests of ...

Histamine response and local cooling in the human skin: involvement of H1- and H2-receptors.

Science.gov (United States)

Grossmann, M; Jamieson, M J; Kirch, W

1999-08-01

Histamine may contribute locally to cutaneous blood flow control under normal and pathologic conditions. The objective of this study was to observe the influence of skin temperature on histamine vasodilation, and the roles of H1-and H2-receptors using novel noninvasive methods. Eleven healthy subjects received, double-blind, single doses of the H1-receptor antagonist cetirizine (10 mg), cetirizine (10 mg) plus the H2-receptor antagonist cimetidine (400 mg), or placebo on separate occasions. Histamine was dosed cumulatively by iontophoresis to the forearm skin at 34 degrees C and 14 degrees C. Laser-Doppler flux (LDF) was measured at the same sites using customised probeholder/iontophoretic chambers with Peltier cooling elements. Finger mean arterial pressure (MAP) was measured and cutaneous vascular conductance calculated as LDF/MAP. Histamine vasodilation was reduced in cold skin. Cetirizine shifted the histamine dose-response at both temperatures: statistically significantly at 14 degrees C only. Combined H1- and H2-receptor antagonism shifted the response significantly at both temperatures. H1- and H2-receptors mediate histamine-induced skin vasodilation. The sensitivity of these receptors, particularly the H1- receptor, is attenuated at low skin temperature. Whether the reduced effect in cold skin represents specific receptor or postreceptor desensitization, or nonspecific attenuation of cutaneous vasodilation remains to be elucidated.

Molecular pharmacology of promiscuous seven transmembrane receptors sensing organic nutrients.

Science.gov (United States)

Wellendorph, Petrine; Johansen, Lars Dan; Bräuner-Osborne, Hans

2009-09-01

A number of highly promiscuous seven transmembrane (7TM) receptors have been cloned and characterized within the last few years. It is noteworthy that many of these receptors are activated broadly by amino acids, proteolytic degradation products, carbohydrates, or free fatty acids and are expressed in taste tissue, the gastrointestinal tract, endocrine glands, adipose tissue, and/or kidney. These receptors thus hold the potential to act as sensors of food intake, regulating, for example, release of incretin hormones from the gut, insulin/glucagon from the pancreas, and leptin from adipose tissue. The promiscuous tendency in ligand recognition of these receptors is in contrast to the typical specific interaction with one physiological agonist seen for most receptors, which challenges the classic "lock-and-key" concept. We here review the molecular mechanisms of nutrient sensing of the calcium-sensing receptor, the G protein-coupled receptor family C, group 6, subtype A (GPRC6A), and the taste1 receptor T1R1/T1R3, which are sensing L-alpha-amino acids, the carbohydrate-sensing T1R2/T1R3 receptor, the proteolytic degradation product sensor GPR93 (also termed GPR92), and the free fatty acid (FFA) sensing receptors FFA1, FFA2, FFA3, GPR84, and GPR120. The involvement of the individual receptors in sensing of food intake has been validated to different degrees because of limited availability of specific pharmacological tools and/or receptor knockout mice. However, as a group, the receptors represent potential drug targets, to treat, for example, type II diabetes by mimicking food intake by potent agonists or positive allosteric modulators. The ligand-receptor interactions of the promiscuous receptors of organic nutrients thus remain an interesting subject of emerging functional importance.

Biological functionalization of drug delivery carriers to bypass size restrictions of receptor-mediated endocytosis independently from receptor targeting.

Science.gov (United States)

Ansar, Maria; Serrano, Daniel; Papademetriou, Iason; Bhowmick, Tridib Kumar; Muro, Silvia

2013-12-23

Targeting of drug carriers to cell-surface receptors involved in endocytosis is commonly used for intracellular drug delivery. However, most endocytic receptors mediate uptake via clathrin or caveolar pathways associated with ≤200-nm vesicles, restricting carrier design. We recently showed that endocytosis mediated by intercellular adhesion molecule 1 (ICAM-1), which differs from clathrin- and caveolae-mediated pathways, allows uptake of nano- and microcarriers in cell culture and in vivo due to recruitment of cellular sphingomyelinases to the plasmalemma. This leads to ceramide generation at carrier binding sites and formation of actin stress-fibers, enabling engulfment and uptake of a wide size-range of carriers. Here we adapted this paradigm to enhance uptake of drug carriers targeted to receptors associated with size-restricted pathways. We coated sphingomyelinase onto model (polystyrene) submicro- and microcarriers targeted to clathrin-associated mannose-6-phosphate receptor. In endothelial cells, this provided ceramide enrichment at the cell surface and actin stress-fiber formation, modifying the uptake pathway and enhancing carrier endocytosis without affecting targeting, endosomal transport, cell-associated degradation, or cell viability. This improvement depended on the carrier size and enzyme dose, and similar results were observed for other receptors (transferrin receptor) and cell types (epithelial cells). This phenomenon also enhanced tissue accumulation of carriers after intravenous injection in mice. Hence, it is possible to maintain targeting toward a selected receptor while bypassing natural size restrictions of its associated endocytic route by functionalization of drug carriers with biological elements mimicking the ICAM-1 pathway. This strategy holds considerable promise to enhance flexibility of design of targeted drug delivery systems.

Mannose receptor may be involved in small ruminant lentivirus pathogenesis

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Crespo Helena

2012-05-01

Full Text Available Abstract Thirty-one sheep naturally infected with small ruminant lentiviruses (SRLV of known genotype (A or B, and clinically affected with neurological disease, pneumonia or arthritis were used to analyse mannose receptor (MR expression (transcript levels and proviral load in virus target tissues (lung, mammary gland, CNS and carpal joints. Control sheep were SRLV-seropositive asymptomatic (n = 3, seronegative (n = 3 or with chronic listeriosis, pseudotuberculosis or parasitic cysts (n = 1 in each case. MR expression and proviral load increased with the severity of lesions in most analyzed organs of the SRLV infected sheep and was detected in the affected tissue involved in the corresponding clinical disease (CNS, lung and carpal joint in neurological disease, pneumonia and arthritis animal groups, respectively. The increased MR expression appeared to be SRLV specific and may have a role in lentiviral pathogenesis.

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

D2-like receptors in the descending dopaminergic pathway are not involved in the decreased postoperative nociceptive threshold induced by plantar incision in adult rats.

Science.gov (United States)

Ohtani, Norimasa; Masaki, Eiji

2016-01-01

Approximately half of all patients who undergo surgery develop postoperative pain, the mechanisms of which are not well understood by anesthesiologists. D2-like receptors in the descending dopaminergic pathway play an important role in regulation of pain transmission in the spinal cord. Impairment of inhibitory neurons in the spinal cord is suggested as part of the mechanism for neuropathic pain, which is one component of postoperative pain. The purpose of this study was to investigate whether impairment of D2-like receptors in the descending dopaminergic pathway in the spinal cord is involved in the decreased postoperative nociceptive threshold in rats. Male Sprague-Dawley rats (250-300 g) were anesthetized with sevoflurane and an intrathecal (IT) catheter was implanted. Six days later, a plantar incision was made. On the following day, saline, a D2-like receptor agonist (quinpirole), or a D2-like receptor antagonist (sulpiride) was administered intrathecally. Thermal and mechanical nociceptive responses were assessed by exposure to infrared radiant heat and the von Frey filament test before and after plantar incision. Plantar incision decreased both thermal latency and the mechanical nociceptive threshold. IT administration of quinpirole inhibited the nociceptive responses induced by plantar incision, but sulpiride had no effect. A D2-like receptor agonist had antinociceptive effects on the hypersensitivity response triggered by a surgical incision, but a D2-like receptor antagonist had no effect on this response. These results suggest that impairment and/or modification of D2-like receptors in the descending dopaminergic pathway in the spinal cord is not involved in the postoperative decrease in nociceptive threshold.

Adenosine Receptor Heteromers and their Integrative Role in Striatal Function

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Sergi Ferré

2007-01-01

Full Text Available By analyzing the functional role of adenosine receptor heteromers, we review a series of new concepts that should modify our classical views of neurotransmission in the central nervous system (CNS. Neurotransmitter receptors cannot be considered as single functional units anymore. Heteromerization of neurotransmitter receptors confers functional entities that possess different biochemical characteristics with respect to the individual components of the heteromer. Some of these characteristics can be used as a “biochemical fingerprint” to identify neurotransmitter receptor heteromers in the CNS. This is exemplified by changes in binding characteristics that are dependent on coactivation of the receptor units of different adenosine receptor heteromers. Neurotransmitter receptor heteromers can act as “processors” of computations that modulate cell signaling, sometimes critically involved in the control of pre- and postsynaptic neurotransmission. For instance, the adenosine A1-A2A receptor heteromer acts as a concentration-dependent switch that controls striatal glutamatergic neurotransmission. Neurotransmitter receptor heteromers play a particularly important integrative role in the “local module” (the minimal portion of one or more neurons and/or one or more glial cells that operates as an independent integrative unit, where they act as processors mediating computations that convey information from diverse volume-transmitted signals. For instance, the adenosine A2A-dopamine D2 receptor heteromers work as integrators of two different neurotransmitters in the striatal spine module.

Sex Hormones and Their Receptors Regulate Liver Energy Homeostasis

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Minqian Shen

2015-01-01

Full Text Available The liver is one of the most essential organs involved in the regulation of energy homeostasis. Hepatic steatosis, a major manifestation of metabolic syndrome, is associated with imbalance between lipid formation and breakdown, glucose production and catabolism, and cholesterol synthesis and secretion. Epidemiological studies show sex difference in the prevalence in fatty liver disease and suggest that sex hormones may play vital roles in regulating hepatic steatosis. In this review, we summarize current literature and discuss the role of estrogens and androgens and the mechanisms through which estrogen receptors and androgen receptors regulate lipid and glucose metabolism in the liver. In females, estradiol regulates liver metabolism via estrogen receptors by decreasing lipogenesis, gluconeogenesis, and fatty acid uptake, while enhancing lipolysis, cholesterol secretion, and glucose catabolism. In males, testosterone works via androgen receptors to increase insulin receptor expression and glycogen synthesis, decrease glucose uptake and lipogenesis, and promote cholesterol storage in the liver. These recent integrated concepts suggest that sex hormone receptors could be potential promising targets for the prevention of hepatic steatosis.

Microglial Scavenger Receptors and Their Roles in the Pathogenesis of Alzheimer's Disease

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Kim Wilkinson

2012-01-01

Full Text Available Alzheimer’s disease (AD is increasing in prevalence with the aging population. Deposition of amyloid-β (Aβ in the brain of AD patients is a hallmark of the disease and is associated with increased microglial numbers and activation state. The interaction of microglia with Aβ appears to play a dichotomous role in AD pathogenesis. On one hand, microglia can phagocytose and clear Aβ, but binding of microglia to Aβ also increases their ability to produce inflammatory cytokines, chemokines, and neurotoxic reactive oxygen species (ROS. Scavenger receptors, a group of evolutionally conserved proteins expressed on the surface of microglia act as receptors for Aβ. Of particular interest are SCARA-1 (scavenger receptor A-1, CD36, and RAGE (receptor for advanced glycation end products. SCARA-1 appears to be involved in the clearance of Aβ, while CD36 and RAGE are involved in activation of microglia by Aβ. In this review, we discuss the roles of various scavenger receptors in the interaction of microglia with Aβ and propose that these receptors play complementary, nonredundant functions in the development of AD pathology. We also discuss potential therapeutic applications for these receptors in AD.

Biochemical and immunological studies of the Muscarinic acetylcholine receptor

International Nuclear Information System (INIS)

Gainer, M.W.

1985-01-01

Muscarinic acetylcholine receptors were solubilized from bovine brain membranes with 3[3-cholamidopropyl)dimethylammonio]propanesulfonate (CHAPS). A combination of 10 mM CHAPS and 1 M NaCl solubilized 15-40% of the specific receptor binding sites from these membranes. The solubilized receptors displayed high affinity binding of the muscarinic antagonist, [ 3 H]quinuclidinyl benzilate with a K/sub D/ = 300 pM. In addition, the solubilized and retained guanyl nucleotide regulation of agonist binding characteristic of membrane bound receptors. Gel filtration experiments showed that solubilized receptors from cortex and cerebellum had different elution profiles. Analysis by sucrose density gradient centrifugation showed that receptors in the lower molecular weight peak sedimented with a coefficient of 5S. Receptors in the larger molecular weight peak sedimented to the bottom of the gradient. Attempts to purify receptors by chromatography on propylbenzilycholine Sepharose were unsuccessful. The technique used to attach the ligand to the solid support, however, was used to synthesize a PrBCM-BSA conjugate and the conjugate used as an antigen in the production of anti-ligand antibodies. Two anti-PrBCM monoclonal antibodies were isolated that recognize muscarinic but not nicotinic cholinergic ligands. The abilities of the antibodies to recognize other muscarinic ligands indicated the antibodies recognized a portion of PrBCM involved in binding to the receptor. Construction of an antibody affinity resin resulted in the purification of this fragment a minimum of 170 fold

Radiolabelled GLP-1 receptor antagonist binds to GLP-1 receptor-expressing human tissues

Energy Technology Data Exchange (ETDEWEB)

Waser, Beatrice; Reubi, Jean Claude [University of Berne, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, PO Box 62, Berne (Switzerland)

2014-06-15

Radiolabelled glucagon-like peptide 1 (GLP-1) receptor agonists have recently been shown to successfully image benign insulinomas in patients. For the somatostatin receptor targeting of tumours, however, it was recently reported that antagonist tracers were superior to agonist tracers. The present study therefore evaluated various forms of the {sup 125}iodinated-Bolton-Hunter (BH)-exendin(9-39) antagonist tracer for the in vitro visualization of GLP-1 receptor-expressing tissues in rats and humans and compared it with the agonist tracer {sup 125}I-GLP-1(7-36)amide. Receptor autoradiography studies with {sup 125}I-GLP-1(7-36)amide agonist or {sup 125}I-BH-exendin(9-39) antagonist radioligands were performed in human and rat tissues. The antagonist {sup 125}I-BH-exendin(9-39) labelled at lysine 19 identifies all human and rat GLP-1 target tissues and GLP-1 receptor-expressing tumours. Binding is of high affinity and is comparable in all tested tissues in its binding properties with the agonist tracer {sup 125}I-GLP-1(7-36)amide. For comparison, {sup 125}I-BH-exendin(9-39) with the BH labelled at lysine 4 did identify the GLP-1 receptor in rat tissues but not in human tissues. The GLP-1 receptor antagonist exendin(9-39) labelled with {sup 125}I-BH at lysine 19 is an excellent GLP-1 radioligand that identifies human and rat GLP-1 receptors in normal and tumoural tissues. It may therefore be the molecular basis to develop suitable GLP-1 receptor antagonist radioligands for in vivo imaging of GLP-1 receptor-expressing tissues in patients. (orig.)

Sigma-1 receptor: The novel intracellular target of neuropsychotherapeutic drugs

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Teruo Hayashi

2015-01-01

Full Text Available Sigma-1 receptor ligands have been long expected to serve as drugs for treatment of human diseases such as neurodegenerative disorders, depression, idiopathic pain, drug abuse, and cancer. Recent research exploring the molecular function of the sigma-1 receptor started unveiling underlying mechanisms of the therapeutic activity of those ligands. Via the molecular chaperone activity, the sigma-1 receptor regulates protein folding/degradation, ER/oxidative stress, and cell survival. The chaperone activity is activated or inhibited by synthetic sigma-1 receptor ligands in an agonist-antagonist manner. Sigma-1 receptors are localized at the endoplasmic reticulum (ER membranes that are physically associated with the mitochondria (MAM: mitochondria-associated ER membrane. In specific types of neurons (e.g., those at the spinal cord, sigma-1 receptors are also clustered at ER membranes that juxtapose postsynaptic plasma membranes. Recent studies indicate that sigma-1 receptors, partly in sake of its unique subcellular localization, regulate the mitochondria function that involves bioenergetics and free radical generation. The sigma-1 receptor may thus provide an intracellular drug target that enables controlling ER stress and free radical generation under pathological conditions.

Dengue virus receptor

OpenAIRE

Hidari, Kazuya I.P.J.; Suzuki, Takashi

2011-01-01

Dengue virus is an arthropod-borne virus transmitted by Aedes mosquitoes. Dengue virus causes fever and hemorrhagic disorders in humans and non-human primates. Direct interaction of the virus introduced by a mosquito bite with host receptor molecule(s) is crucial for virus propagation and the pathological progression of dengue diseases. Therefore, elucidation of the molecular mechanisms underlying the interaction between dengue virus and its receptor(s) in both humans and mosquitoes is essent...

Conformational transitions and interactions underlying the function of membrane embedded receptor protein kinases.

Science.gov (United States)

Bocharov, Eduard V; Sharonov, Georgy V; Bocharova, Olga V; Pavlov, Konstantin V

2017-09-01

Among membrane receptors, the single-span receptor protein kinases occupy a broad but specific functional niche determined by distinctive features of the underlying transmembrane signaling mechanisms that are briefly overviewed on the basis of some of the most representative examples, followed by a more detailed discussion of several hierarchical levels of organization and interactions involved. All these levels, including single-molecule interactions (e.g., dimerization, liganding, chemical modifications), local processes (e.g. lipid membrane perturbations, cytoskeletal interactions), and larger scale phenomena (e.g., effects of membrane surface shape or electrochemical potential gradients) appear to be closely integrated to achieve the observed diversity of the receptor functioning. Different species of receptor protein kinases meet their specific functional demands through different structural features defining their responses to stimulation, but certain common patterns exist. Signaling by receptor protein kinases is typically associated with the receptor dimerization and clustering, ligand-induced rearrangements of receptor domains through allosteric conformational transitions with involvement of lipids, release of the sequestered lipids, restriction of receptor diffusion, cytoskeleton and membrane shape remodeling. Understanding of complexity and continuity of the signaling processes can help identifying currently neglected opportunities for influencing the receptor signaling with potential therapeutic implications. This article is part of a Special Issue entitled: Interactions between membrane receptors in cellular membranes edited by Kalina Hristova. Copyright © 2017 Elsevier B.V. All rights reserved.

Structure and assembly mechanism for heteromeric kainate receptors.

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Kumar, Janesh; Schuck, Peter; Mayer, Mark L

2011-07-28

Native glutamate receptor ion channels are tetrameric assemblies containing two or more different subunits. NMDA receptors are obligate heteromers formed by coassembly of two or three divergent gene families. While some AMPA and kainate receptors can form functional homomeric ion channels, the KA1 and KA2 subunits are obligate heteromers which function only in combination with GluR5-7. The mechanisms controlling glutamate receptor assembly involve an initial step in which the amino terminal domains (ATD) assemble as dimers. Here, we establish by sedimentation velocity that the ATDs of GluR6 and KA2 coassemble as a heterodimer of K(d) 11 nM, 32,000-fold lower than the K(d) for homodimer formation by KA2; we solve crystal structures for the GluR6/KA2 ATD heterodimer and heterotetramer assemblies. Using these structures as a guide, we perform a mutant cycle analysis to probe the energetics of assembly and show that high-affinity ATD interactions are required for biosynthesis of functional heteromeric receptors. Copyright © 2011 Elsevier Inc. All rights reserved.

Involvement of Striatal Cholinergic Interneurons and M1 and M4 Muscarinic Receptors in Motor Symptoms of Parkinson's Disease.

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Ztaou, Samira; Maurice, Nicolas; Camon, Jeremy; Guiraudie-Capraz, Gaëlle; Kerkerian-Le Goff, Lydia; Beurrier, Corinne; Liberge, Martine; Amalric, Marianne

2016-08-31

Over the last decade, striatal cholinergic interneurons (ChIs) have reemerged as key actors in the pathophysiology of basal-ganglia-related movement disorders. However, the mechanisms involved are still unclear. In this study, we address the role of ChI activity in the expression of parkinsonian-like motor deficits in a unilateral nigrostriatal 6-hydroxydopamine (6-OHDA) lesion model using optogenetic and pharmacological approaches. Dorsal striatal photoinhibition of ChIs in lesioned ChAT(cre/cre) mice expressing halorhodopsin in ChIs reduces akinesia, bradykinesia, and sensorimotor neglect. Muscarinic acetylcholine receptor (mAChR) blockade by scopolamine produces similar anti-parkinsonian effects. To decipher which of the mAChR subtypes provides these beneficial effects, systemic and intrastriatal administration of the selective M1 and M4 mAChR antagonists telenzepine and tropicamide, respectively, were tested in the same model of Parkinson's disease. The two compounds alleviate 6-OHDA lesion-induced motor deficits. Telenzepine produces its beneficial effects by blocking postsynaptic M1 mAChRs expressed on medium spiny neurons (MSNs) at the origin of the indirect striatopallidal and direct striatonigral pathways. The anti-parkinsonian effects of tropicamide were almost completely abolished in mutant lesioned mice that lack M4 mAChRs specifically in dopamine D1-receptor-expressing neurons, suggesting that postsynaptic M4 mAChRs expressed on direct MSNs mediate the antiakinetic action of tropicamide. The present results show that altered cholinergic transmission via M1 and M4 mAChRs of the dorsal striatum plays a pivotal role in the occurrence of motor symptoms in Parkinson's disease. The striatum, where dopaminergic and cholinergic systems interact, is the pivotal structure of basal ganglia involved in pathophysiological changes underlying Parkinson's disease. Here, using optogenetic and pharmacological approaches, we investigated the involvement of striatal

Syntheses of 7-Substituted α-Cyperone Derivatives for Selective Sigma-1 Receptor over Cannabinoid-1 Receptor Binding Affinities

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Park, Juyoung; Shin, Younggyun; Yoon, Sunghwa [Ajou Univ., Suwon (Korea, Republic of); Kim, Keewon; Kwon, Youngbae [ChonBuk National Univ., Jeonju (Korea, Republic of)

2013-11-15

We have successfully synthesized seven α-cyperone derivatives and found that the presence of a hydrogen bond donor/acceptor groups at the C7 position of α-cyperone significantly affects specificity and potency of CB{sub 1} receptor binding affinity over sigma-1 receptor binding affinity. In particular, the presence of the amino moiety at the C7 position of α-cyperone is beneficial for binding to sigmia-1 receptor. The molecular mechanism of compound 8 involved in the high binding affinity to sigma-1 receptor is under investigation. We first synthesized α-cyperone 1 by following the previously reported synthetic routes.15-19 In brief, azeotropic imination of (+)-dihydrocarvone and (R)-(+)-1-phenylethylamine followed by alkylation with a slight excess of ethyl vinyl ketone (EVK) in THF at 40 .deg. C produced the Micheal adduct. The resulting adduct was hydrolyzed and then treated with sodium methoxide at room temperature to give an easily separable mixture of α-cyperone 1 and its side product. Flash chromatography resulted in pure α-cyperone 1 in a 30% yield from (+)-dihydrocarvone.

Increased hypothalamic 5-HT2A receptor gene expression and effects of pharmacologic 5-HT2A receptor inactivation in obese Ay mice

International Nuclear Information System (INIS)

Nonogaki, Katsunori; Nozue, Kana; Oka, Yoshitomo

2006-01-01

Serotonin (5-hydroxytryptamine; 5-HT) 2A receptors contribute to the effects of 5-HT on platelet aggregation and vascular smooth muscle cell proliferation, and are reportedly involved in decreases in plasma levels of adiponectin, an adipokine, in diabetic subjects. Here, we report that systemic administration of sarpogrelate, a 5-HT2A receptor antagonist, suppressed appetite and increased hypothalamic pro-opiomelanocortin and cocaine- and amphetamine-regulated transcript, corticotropin releasing hormone, 5-HT2C, and 5-HT1B receptor gene expression. A y mice, which have ectopic expression of the agouti protein, significantly increased hypothalamic 5-HT2A receptor gene expression in association with obesity compared with wild-type mice matched for age. Systemic administration of sarpogrelate suppressed overfeeding, body weight gain, and hyperglycemia in obese A y mice, whereas it did not increase plasma adiponectin levels. These results suggest that obesity increases hypothalamic 5-HT2A receptor gene expression, and pharmacologic inactivation of 5-HT2A receptors inhibits overfeeding and obesity in A y mice, but did not increase plasma adiponectin levels

Repeated blockade of mineralocorticoid receptors, but not of glucocorticoid receptors impairs food rewarded spatial learning

NARCIS (Netherlands)

Douma, B. R.; Korte, S. M.; Buwalda, B.; La Fleur, S. E.; Bohus, B.; Luiten, P. G.

1998-01-01

Corticosteroids from the adrenal cortex influence a variety of behaviours including cognition, learning and memory. These hormones act via two intracellular receptors, the mineralo-corticoid receptor (MR) and the glucocorticoid receptor (GR). These two receptor types display a high concentration and

Repeated blockade of mineralocorticoid receptors, but not of glucocorticoid receptors impairs food rewarded spatial learning

NARCIS (Netherlands)

Douma, BRK; Korte, SM; Buwalda, B; la Fleur, SE; Bohus, B; Luiten, PGM

Corticosteroids from the adrenal cortex influence a variety of behaviours including cognition, learning and memory. These hormones act via two intracellular receptors, the mineralo-corticoid receptor (MR) and the glucocorticoid receptor (GR). These two receptor types display a high concentration and

Functional Consequences of Glucagon-like Peptide-1 Receptor Cross-talk and Trafficking

DEFF Research Database (Denmark)

Roed, Sarah Noerklit; Nøhr, Anne Cathrine; Wismann, Pernille

2015-01-01

The signaling capacity of seven-transmembrane/G-protein-coupled receptors (7TM/GPCRs) can be regulated through ligand-mediated receptor trafficking. Classically, the recycling of internalized receptors is associated with resensitization, whereas receptor degradation terminates signaling. We have......) and glucagon (GCGR) receptors. The interaction and cross-talk between coexpressed receptors is a wide phenomenon of the 7TM/GPCR superfamily. Numerous reports show functional consequences for signaling and trafficking of the involved receptors. On the basis of the high structural similarity and tissue...... coexpression, we here investigated the potential cross-talk between GLP-1R and GIPR or GCGR in both trafficking and signaling pathways. Using a real-time time-resolved FRET-based internalization assay, we show that GLP-1R, GIPR, and GCGR internalize with differential properties. Remarkably, upon coexpression...

Distinct Subunit Domains Govern Synaptic Stability and Specificity of the Kainate Receptor

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Christoph Straub

2016-07-01

Full Text Available Synaptic communication between neurons requires the precise localization of neurotransmitter receptors to the correct synapse type. Kainate-type glutamate receptors restrict synaptic localization that is determined by the afferent presynaptic connection. The mechanisms that govern this input-specific synaptic localization remain unclear. Here, we examine how subunit composition and specific subunit domains contribute to synaptic localization of kainate receptors. The cytoplasmic domain of the GluK2 low-affinity subunit stabilizes kainate receptors at synapses. In contrast, the extracellular domain of the GluK4/5 high-affinity subunit synergistically controls the synaptic specificity of kainate receptors through interaction with C1q-like proteins. Thus, the input-specific synaptic localization of the native kainate receptor complex involves two mechanisms that underlie specificity and stabilization of the receptor at synapses.

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.

Pathophysiological consequences of receptor mistraffic: Tales from the platelet P2Y12 receptor.

Science.gov (United States)

Cunningham, Margaret R; Aungraheeta, Riyaad; Mundell, Stuart J

2017-07-05

Genetic variations in G protein-coupled receptor (GPCR) genes can disrupt receptor function in a wide variety of human genetic diseases, including platelet bleeding disorders. Platelets are critical for haemostasis with inappropriate platelet activation leading to the development of arterial thrombosis, which can result in heart attack and stroke whilst decreased platelet activity is associated with an increased risk of bleeding. GPCRs expressed on the surface of platelets play key roles in regulating platelet activity and therefore function. Receptors include purinergic receptors (P2Y 1 and P2Y 12 ), proteinase-activated receptor (PAR1 and PAR4) and thromboxane receptors (TPα), among others. Pharmacological blockade of these receptors forms a powerful therapeutic tool in the treatment and prevention of arterial thrombosis. With the advance of genomic technologies, there has been a substantial increase in the identification of naturally occurring rare and common GPCR variants. These variants include single-nucleotide polymorphisms (SNPs) and insertion or deletions that have the potential to alter GPCR expression or function. A number of defects in platelet GPCRs that disrupt receptor function have now been characterized in patients with mild bleeding disorders. This review will focus on rare, function-disrupting variants of platelet GPCRs with particular emphasis upon mutations in the P2Y 12 receptor gene that affect receptor traffic to modulate platelet function. Further this review will outline how the identification and characterization of function-disrupting GPCR mutations provides an essential link in translating our detailed understanding of receptor traffic and function in cell line studies into relevant human biological systems. Copyright © 2017. Published by Elsevier B.V.

Effects of caffeine on striatal neurotransmission: focus on cannabinoid CB1 receptors.

Science.gov (United States)

Rossi, Silvia; De Chiara, Valentina; Musella, Alessandra; Mataluni, Giorgia; Sacchetti, Lucia; Siracusano, Alberto; Bernardi, Giorgio; Usiello, Alessandro; Centonze, Diego

2010-04-01

Caffeine is the most commonly self-administered psychoactive substance worldwide. At usual doses, the effects of caffeine on vigilance, attention, mood and arousal largely depend on the modulation of central adenosine receptors. The present review article describes the action of caffeine within the striatum, to provide a possible molecular mechanism at the basis of the psychomotor and reinforcing properties of this pharmacological agent. The striatum is in fact a subcortical area involved in sensorimotor, cognitive, and emotional processes, and recent experimental findings showed that chronic caffeine consumption enhances the sensitivity of striatal GABAergic synapses to the stimulation of cannabinoid CB1 receptors. The endocannabinoid system is involved in the psychoactive effects of many compounds, and adenosine A2A receptors (the main receptor target of caffeine) elicit a permissive effect towards CB1 receptors, thus suggesting that A2A-CB1 receptor interaction plays a major role in the generation and maintenance of caffeine reinforcing behavior. Aim of this review is to describe the effects of caffeine on striatal neurotransmission with special reference to the modulation of the endocannabinoid system.

Modulation of type II TGF-β receptor degradation by integrin-linked kinase.

Science.gov (United States)

Vi, Linda; Boo, Stellar; Sayedyahossein, Samar; Singh, Randeep K; McLean, Sarah; Di Guglielmo, Gianni M; Dagnino, Lina

2015-03-01

Cutaneous responses to injury, infection, and tumor formation involve the activation of resident dermal fibroblasts and subsequent transition to myofibroblasts. The key for induction of myofibroblast differentiation is the activation of transforming growth factor-β (TGF-β) receptors and stimulation of integrins and their associated proteins, including integrin-linked kinase (ILK). Cross-talk processes between TGF-β and ILK are crucial for myofibroblast formation, as ILK-deficient dermal fibroblasts exhibit impaired responses to TGF-β receptor stimulation. We now show that ILK associates with type II TGF-β receptors (TβRII) in ligand- and receptor kinase activity-independent manners. In cells with targeted Ilk gene inactivation, cellular levels of TβRII are decreased, through mechanisms that involve enhanced ubiquitination and proteasomal degradation. Partitioning of TGF-β receptors into membrane has been linked to proteasome-dependent receptor degradation. We found that interfering with membrane raft formation in ILK-deficient cells restored TβRII levels and signaling. These observations support a model whereby ILK functions in fibroblasts to direct TβRII away from degradative pathways during their differentiation into myofibroblasts.

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

Pharmacologic implications of peroxisome proliferator activated receptors (PPAR Implicaciones farmacológicas de los receptores activados por los proliferadores de peroxisomas (PPAR

Directory of Open Access Journals (Sweden)

Luis Carlos Mejía Rivera

2001-01-01

Full Text Available PPAR are a group of proteins, members of the receptors located within the nucleus. These receptors modulate DNA transcriptional activity by binding to specific response elements on target genes. To date, three main types of PPAR have been identified designed α, δand γthese receptors are involved in the regulation of diferent metabolic processes, being the group of receptors more intensely studied. PPARαare greatly involved in both catabolism of fatty acids and transport of extracellular lipids; fibrates, their agonists, are of proved usefulness in some dyslipidemias. Thiazolidinediones used as antihyperglicemiant agents are PPARγagonists, but their relationship with carbohydrate metabolism is not yet clear; nevertheless, their use in the management of type 2 diabetes mellitus is of increasing importance. On the other hand, nonsteroidal anti-inflammatory agents are somehow related with PPARδfunctions; up to date a molecular and epidemiologic relationship of these drugs and receptors with colon cancer has been established. Los receptores activados por los proliferadores de peroxisomas (PPAR son un grupo de proteínas pertenecientes a la familia de receptores de ubicación nuclear que se comportan como factores que modulan la transcripción del DNA al unirse a elementos de respuesta específicos de ciertos genes blanco. Hasta el momento se han descrito tres tipos principales de PPAR designados como α, δ, y γ; estos receptores se encuentran involucrados en la regulación de diferentes procesos metabólicos; por esto se han convertido en uno de los grupos de receptores más intensamente estudiados. Los PPARα participan tanto en el catabolismo de los ácidos grasos como en el transporte extracelular de lípidos; los fibratos, sus agonistas, tienen utilidad ampliamente demostrada en el manejo de algunas dislipidemias. Las tiazolidindionas utilizadas como fármacos antihiperglicemiantes son agonistas de los PPARγ; todav

Acetylcholine receptor antibody

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... medlineplus.gov/ency/article/003576.htm Acetylcholine receptor antibody To use the sharing features on this page, please enable JavaScript. Acetylcholine receptor antibody is a protein found in the blood of ...

Cellular receptors for human enterovirus species A

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Yorihiro eNishimura

2012-03-01

Full Text Available Human enterovirus species A (HEV-A is one of the four species of HEV in the genus Enterovirus in the family Picornaviridae. Among HEV-A, coxsackievirus A16 (CVA16 and enterovirus 71 (EV71 are the major causative agents of hand, foot, and mouth disease (HFMD. Some other types of HEV-A are commonly associated with herpangina. Although HFMD and herpangina due to HEV-A are common febrile diseases among infants and children, EV71 can cause various neurological diseases, such as aseptic meningitis and fatal encephalitis.Recently, two human transmembrane proteins, P-selectin glycoprotein ligand-1 (PSGL-1 and scavenger receptor class B, member 2 (SCARB2, were identified as functional receptors for EV71 and CVA16. In in vitro infection experiments using the prototype HEV-A strains, PSGL-1 and SCARB2 could be responsible for the specific receptors for EV71 and CVA16. However, the involvement of both receptors in the in vitro and in vivo infections of clinical isolates of HEV-A has not been clarified yet. To elucidate a diverse array of the clinical outcome of HEV-A-associated diseases, the identification and characterization of HEV-A receptors may provide useful information in understanding the HEV-A pathogenesis at a molecular level.

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

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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.

L-glutamate Receptor In Paramecium

Science.gov (United States)

Bernal-Martínez, Juan; Ortega-Soto, Arturo

2004-09-01

Behavioral, electrophysiological and biochemical experiments were performed in order to establish the presence of a glutamate receptor in the ciliate Paramecium. It was found that an AMPA/KA receptor is functionally expressed in Paramecium and that this receptor is immunologically and fillogenetically related to the AMPA/KA receptor present in vertebrates.

Do receptors get pregnant too? Adrenergic receptor alterations in human pregnancy.

Science.gov (United States)

Smiley, R M; Finster, M

1996-01-01

In this review we discuss adrenergic receptor number and function during pregnancy, with emphasis on evidence that pregnancy results in specific receptor alterations from the nonpregnant state. Changes in adrenergic receptor function or distribution in vascular smooth muscle may be in part responsible for the decreased vascular responsiveness seen in human pregnancy, and the lack of the normal alterations may be a part of the syndromes of gestational hypertension, including preeclampsia-eclampsia. The onset of labor may be influenced by adrenergic modulation, and receptor or postreceptor level molecular alterations may trigger or facilitate normal or preterm labor. Human studies are emphasized when possible to assess the role of adrenergic signal transduction regulation in the physiology and pathophysiology of normal and complicated human pregnancy.

Bone phenotypes of P2 receptor knockout mice

DEFF Research Database (Denmark)

Orriss, Isabel; Syberg, Susanne; Wang, Ning

2011-01-01

The action of extracellular nucleotides is mediated by ionotropic P2X receptors and G-protein coupled P2Y receptors. The human genome contains 7 P2X and 8 P2Y receptor genes. Knockout mice strains are available for most of them. As their phenotypic analysis is progressing, bone abnormalities have...... been observed in an impressive number of these mice: distinct abnormalities in P2X7-/- mice, depending on the gene targeting construct and the genetic background, decreased bone mass in P2Y1-/- mice, increased bone mass in P2Y2-/- mice, decreased bone resorption in P2Y6-/- mice, decreased bone...... formation and bone resorption in P2Y13-/- mice. These findings demonstrate the unexpected importance of extracellular nucleotide signalling in the regulation of bone metabolism via multiple P2 receptors and distinct mechanisms involving both osteoblasts and osteoclasts....

Clinical and Genomic Crosstalk between Glucocorticoid Receptor and Estrogen Receptor α In Endometrial Cancer

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Jeffery M. Vahrenkamp

2018-03-01

Full Text Available Summary: Steroid hormone receptors are simultaneously active in many tissues and are capable of altering each other’s function. Estrogen receptor α (ER and glucocorticoid receptor (GR are expressed in the uterus, and their ligands have opposing effects on uterine growth. In endometrial tumors with high ER expression, we surprisingly found that expression of GR is associated with poor prognosis. Dexamethasone reduced normal uterine growth in vivo; however, this growth inhibition was abolished in estrogen-induced endometrial hyperplasia. We observed low genomic-binding site overlap when ER and GR are induced with their respective ligands; however, upon simultaneous induction they co-occupy more sites. GR binding is altered significantly by estradiol with GR recruited to ER-bound loci that become more accessible upon estradiol induction. Gene expression responses to co-treatment were more similar to estradiol but with additional regulated genes. Our results suggest phenotypic and molecular interplay between ER and GR in endometrial cancer. : Estrogen receptor α (ER and glucocorticoid receptor (GR are expressed in the uterus and have differential effects on growth. Vahrenkamp et al. find that expression of both receptors is associated with poor outcome in endometrial cancer and that simultaneous induction of ER and GR leads to molecular interplay between the receptors. Keywords: estrogen receptor, glucocorticoid receptor, endometrial cancer

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

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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.

Presynaptic Muscarinic Acetylcholine Receptors and TrkB Receptor Cooperate in the Elimination of Redundant Motor Nerve Terminals during Development.

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Nadal, Laura; Garcia, Neus; Hurtado, Erica; Simó, Anna; Tomàs, Marta; Lanuza, Maria A; Cilleros, Victor; Tomàs, Josep

2017-01-01

The development of the nervous system involves the overproduction of synapses but connectivity is refined by Hebbian activity-dependent axonal competition. The newborn skeletal muscle fibers are polyinnervated but, at the end of the competition process, some days later, become innervated by a single axon. We used quantitative confocal imaging of the autofluorescent axons from transgenic B6.Cg-Tg (Thy1-YFP)16 Jrs/J mice to investigate the possible cooperation of the muscarinic autoreceptors (mAChR, M 1 -, M 2 - and M 4 -subtypes) and the tyrosine kinase B (TrkB) receptor in the control of axonal elimination after the mice Levator auris longus (LAL) muscle had been exposed to several selective antagonist of the corresponding receptor pathways in vivo . Our previous results show that M 1 , M 2 and TrkB signaling individually increase axonal loss rate around P9. Here we show that although the M 1 and TrkB receptors cooperate and add their respective individual effects to increase axonal elimination rate even more, the effect of the M 2 receptor is largely independent of both M 1 and TrkB receptors. Thus both, cooperative and non-cooperative signaling mechanisms contribute to developmental synapse elimination.

Localización extra nuclear de receptores esteroides y activación de mecanismos no genómicos Extra nuclear localization of steroid receptors and non genomic activation mechanisms

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María Cecilia Bottino

2010-04-01

Full Text Available Los receptores de hormonas esteroides han sido considerados históricamente como factores de transcripción nucleares. Sin embargo, en los últimos años surgieron evidencias que indican que su activación desencadena eventos rápidos, independientes de la transcripción y que involucran a diferentes segundos mensajeros; muchos de estos receptores han sido localizados en la membrana celular. Por otra parte, se han caracterizado varios receptores de hormonas esteroides noveles, de estructura molecular diferente al receptor clásico, localizados principalmente en la membrana celular. Esta revisión enfoca los diferentes efectos iniciados por los glucocorticoides, mineralocorticoides, andrógenos, estrógenos y progesterona, y los posibles receptores involucrados en los mismos.Steroid hormone receptors have been historically considered as nuclear transcription factors. Nevertheless, in the last years, many of them have been detected in the cellular membrane. It has been postulated that their activation can induce transcription independent rapid events involving different second messengers. In addition, several novel steroid hormone receptors, showing a different molecular structure than the classical ones, have also been characterized and most of them are also located in the plasmatic membrane. This review focuses on the variety of effects initiated by glucocorticoids, mineralocorticoids, androgens, estrogens and progesterone, and the possible receptors involved mediating these effects.

A complex pattern of chemokine receptor expression is seen in osteosarcoma

International Nuclear Information System (INIS)

Luettichau, Irene von; Huss, Ralf; Nelson, Peter J; Segerer, Stephan; Wechselberger, Alexandra; Notohamiprodjo, Mike; Nathrath, Michaela; Kremer, Markus; Henger, Anna; Djafarzadeh, Roghieh; Burdach, Stefan

2008-01-01

Osteosarcoma is the most frequent bone tumor in childhood and adolescence. Patients with primary metastatic disease have a poor prognosis. It is therefore important to better characterize the biology of this tumor to define new prognostic markers or therapeutic targets for tailored therapy. Chemokines and their receptors have been shown to be involved in the development and progression of malignant tumors. They are thought to be active participants in the biology of osteosarcoma. The function of specific chemokines and their receptors is strongly associated with the biological context and microenvironment of their expression. In this report we characterized the expression of a series of chemokine receptors in the complex environment that defines osteosarcoma. The overall level of chemokine receptor mRNA expression was determined using TaqMan RT-PCR of microdissected archival patient biopsy samples. Expression was then verified at the protein level by immunohistochemistry using a series of receptor specific antibody reagents to elucidate the cellular association of expression. Expression at the RNA level was found for most of the tested receptors. CCR1 expression was found on infiltrating mononuclear and polynuclear giant cells in the tumor. Cells associated with the lining of intratumoral vessels were shown to express CCR4. Infiltrating mononuclear cells and tumor cells both showed expression of the receptor CCR5, while CCR7 was predominantly expressed by the mononuclear infiltrate. CCR10 was only very rarely detected in few scattered infiltrating cells. Our data elucidate for the first time the cellular context of chemokine receptor expression in osteosarcoma. This is an important issue for better understanding potential chemokine/chemokine receptor function in the complex biologic processes that underlie the development and progression of osteosarcoma. Our data support the suggested involvement of chemokines and their receptors in diverse aspects of the biology

Sigma-1 Receptor Plays a Negative Modulation on N-type Calcium Channel

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Kang Zhang

2017-05-01

Full Text Available The sigma-1 receptor is a 223 amino acids molecular chaperone with a single transmembrane domain. It is resident to eukaryotic mitochondrial-associated endoplasmic reticulum and plasma membranes. By chaperone-mediated interactions with ion channels, G-protein coupled receptors and cell-signaling molecules, the sigma-1 receptor performs broad physiological and pharmacological functions. Despite sigma-1 receptors have been confirmed to regulate various types of ion channels, the relationship between the sigma-1 receptor and N-type Ca2+ channel is still unclear. Considering both sigma-1 receptors and N-type Ca2+ channels are involved in intracellular calcium homeostasis and neurotransmission, we undertake studies to explore the possible interaction between these two proteins. In the experiment, we confirmed the expression of the sigma-1 receptors and the N-type calcium channels in the cholinergic interneurons (ChIs in rat striatum by using single-cell reverse transcription-polymerase chain reaction (scRT-PCR and immunofluorescence staining. N-type Ca2+ currents recorded from ChIs in the brain slice of rat striatum was depressed when sigma-1 receptor agonists (SKF-10047 and Pre-084 were administrated. The inhibition was completely abolished by sigma-1 receptor antagonist (BD-1063. Co-expression of the sigma-1 receptors and the N-type calcium channels in Xenopus oocytes presented a decrease of N-type Ca2+ current amplitude with an increase of sigma-1 receptor expression. SKF-10047 could further depress N-type Ca2+ currents recorded from oocytes. The fluorescence resonance energy transfer (FRET assays and co-immunoprecipitation (Co-IP demonstrated that sigma-1 receptors and N-type Ca2+ channels formed a protein complex when they were co-expressed in HEK-293T (Human Embryonic Kidney -293T cells. Our results revealed that the sigma-1 receptors played a negative modulation on N-type Ca2+ channels. The mechanism for the inhibition of sigma-1 receptors on

Receptor binding radiotracers for the angiotensin II receptor: radioiodinated [Sar1, Ile8]angiotensin II

International Nuclear Information System (INIS)

Gibson, R.E.; Beauchamp, H.T.; Fioravanti, C.; Brenner, N.; Burns, H.D.

1994-01-01

The potential for imaging the angiotensin II receptor was evaluated using the radioiodinated peptide antagonist [ 125 I][Sar 1 , Ile 8 ]angiotensin II. The radioligand provides a receptor-mediated signal in several tissues in rat (kidneys, adrenal and liver). The receptor-mediated signal of 3% ID/g kidney cortex should be sufficient to permit imaging, at least via SPECT. The radiotracer is sensitive to reductions in receptor concentration and can be used to define in vivo dose-occupancy curves of angiotensin II receptor ligands. Receptor-mediated images of [ 123 I][Sar 1 , Ile 8 ]angiotensin II were obtained in the rat kidney and Rhesus monkey liver. (author)

NR4A nuclear receptors are orphans but not lonesome

NARCIS (Netherlands)

Kurakula, Kondababu; Koenis, Duco S.; van Tiel, Claudia M.; de Vries, Carlie J. M.

2014-01-01

The NR4A subfamily of nuclear receptors consists of three mammalian members: Nur77, Nurr1, and NOR-1. The NR4A receptors are involved in essential physiological processes such as adaptive and innate immune cell differentiation, metabolism and brain function. They act as transcription factors that

The lactate receptor, G-protein-coupled receptor 81/hydroxycarboxylic acid receptor 1

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Morland, Cecilie; Lauritzen, Knut Huso; Puchades, Maja

2015-01-01

We have proposed that lactate is a “volume transmitter” in the brain and underpinned this by showing that the lactate receptor, G-protein-coupled receptor 81 (GPR81, also known as HCA1 or HCAR1), which promotes lipid storage in adipocytes, is also active in the mammalian brain. This includes......, energy metabolism, and energy substrate availability, including a glucose- and glycogen-saving response. HCAR1 may contribute to optimizing the cAMP concentration. For instance, in the prefrontal cortex, excessively high cAMP levels are implicated in impaired cognition in old age, fatigue, stress...

Receptor-mediated targeting of 67Ga-Deferoxamine-Folate to folate-receptor-positive human kb tumor xenografts

International Nuclear Information System (INIS)

Mathias, Carla J.; Wang, Susan; Low, Philip S.; Waters, David J.; Green, Mark A.

1999-01-01

The radiochemical synthesis and stability of 67 Ga-deferoxamine-folate ([ 67 Ga]Ga-DF-Folate) were examined as a function of DF-Folate concentration. Optimal labeling occurred at DF-Folate concentrations ≥2.5 μg/mL. To define the possible biological significance of variations in product formulation, the biodistribution of [ 67 Ga]Ga-DF-Folate was examined as a function of administered deferoxamine-folate dose in an athymic mouse KB tumor model. The folate-receptor-positive KB tumors were found to concentrate the 67 Ga radiolabel in a dose-dependent fashion, consistent with saturable involvement of the folate receptor in mediating tumor accumulation of the radiopharmaceutical

Analysis of the 5-HT receptor in rabbit saphenous vein exemplifies the problems of using exclusion criteria for receptor classification.

Science.gov (United States)

Martin, G R; MacLennan, S J

1990-08-01

5-Hydroxytryptamine (5-HT) contracts ring preparations of rabbit saphenous vein via direct and indirect components, the latter being compatible with a "tyramine-like" action at sympathetic nerve terminals. Here an attempt was made to establish the identity of the receptor mediating contraction directly, in terms of the currently accepted proposals (Bradley et al. 1986). Results with agonists suggested 5-HT1-like receptor activation: methylsergide behaved as a partial agonist with microcolar affinity and 5-HT effects were mimicked by 5-carboxamidotryptamine (5-CT) and GR43175. The agonist potency order was 5-CT greater than 5-HT greater than methysergide greater than or equal to GR43175, the same as that reported at the 5-HT1-like receptor in dog saphenous vein (Feniuk et al. 1985; Humphrey et al. 1988). Consistent with this, 5-HT effects were resistant to blockade by the selective 5-HT3 receptor antagonist MDL72222 (1.0 mumol/l). In contrast, methiothepin (0.01-0.3 mumol/l), ketanserin (0.3-30.0 mumol/l) and spiperone (0.3-30.0 mumol/l) each produced surmountable antagonism which, although competitive in nature only for methiothepin (pKB = 9.45 +/- 0.09, 17 d.f.), implied 5-HT2 receptor involvement. The possibility that these discrepancies resulted from mixed populations of 5-HT1-like and 5-HT2 receptors can be excluded because; 1). Ketanserin and spiperone blocked the actions of 5-HT and the selective 5-HT1-like receptor agonist GR43175 with equal facility and 2). Responses to all of the agonists studied were similarly antagonised by flesinoxan (pKB approximately 6.4), a simple competitive antagonist at the receptor in rabbit saphenous vein.(ABSTRACT TRUNCATED AT 250 WORDS)

The asymmetric binding of PGC-1α to the ERRα and ERRγ nuclear receptor homodimers involves a similar recognition mechanism.

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Maria Takacs

Full Text Available PGC-1α is a crucial regulator of cellular metabolism and energy homeostasis that functionally acts together with the estrogen-related receptors (ERRα and ERRγ in the regulation of mitochondrial and metabolic gene networks. Dimerization of the ERRs is a pre-requisite for interactions with PGC-1α and other coactivators, eventually leading to transactivation. It was suggested recently (Devarakonda et al that PGC-1α binds in a strikingly different manner to ERRγ ligand-binding domains (LBDs compared to its mode of binding to ERRα and other nuclear receptors (NRs, where it interacts directly with the two ERRγ homodimer subunits.Here, we show that PGC-1α receptor interacting domain (RID binds in an almost identical manner to ERRα and ERRγ homodimers. Microscale thermophoresis demonstrated that the interactions between PGC-1α RID and ERR LBDs involve a single receptor subunit through high-affinity, ERR-specific L3 and low-affinity L2 interactions. NMR studies further defined the limits of PGC-1α RID that interacts with ERRs. Consistent with these findings, the solution structures of PGC-1α/ERRα LBDs and PGC-1α/ERRγ LBDs complexes share an identical architecture with an asymmetric binding of PGC-1α to homodimeric ERR.These studies provide the molecular determinants for the specificity of interactions between PGC-1α and the ERRs, whereby negative cooperativity prevails in the binding of the coactivators to these receptors. Our work indicates that allosteric regulation may be a general mechanism controlling the binding of the coactivators to homodimers.

Involvement of β3-adrenergic receptors in the control of food intake in rats.

Science.gov (United States)

Kanzler, S A; Januario, A C; Paschoalini, M A

2011-11-01

This study examined the food intake changes evoked by intracerebroventricular (icv) injection of a selective agonist (BRL37344, 2 and 20 nmol) or antagonist (SR59230A, 10 and 50 nmol) of β3-adrenergic receptors in 24-h fasted rats (adult male Wistar rats, 200-350 g, N = 6/treatment). The animals were also pretreated with saline icv (SAL) or SR59230A (50 nmol) followed by BRL37344 (20 nmol) or SAL in order to determine the selectivity of the effects evoked by BRL37344 on food intake or the selectivity of the effects evoked by SR59230A on risk assessment (RA) behavior. The highest dose of BRL37344 (N = 7) decreased food intake 1 h after the treatment (6.4 ± 0.5 g in SAL-treated vs 4.2 ± 0.8 g in drug-treated rats). While both doses of SR59230A failed to affect food intake (5.1 ± 1.1 g for 10 nmol and 6.0 ± 1.8 g for 50 nmol), this treatment reduced the RA frequency (number/30 min) (4 ± 2 for SAL-treated vs 1 ± 1 for 10 nmol and 0.5 ± 1 for 50 nmol SR59230A-treated rats), an ethological parameter related to anxiety. While pretreatment with SR59230A (7.0 ± 0.5 g) abolished the hypophagia induced by BRL37344 (3.6 ± 0.9 g), BRL37344 suppressed the reduction in RA frequency caused by SR59230A. These results show that the hypophagia caused by BRL37344 is selectively mediated by β3-adrenergic receptors within the central nervous system. Moreover, they suggest the involvement of these receptors in the control of anxiety.

Involvement of β3-adrenergic receptors in the control of food intake in rats

Directory of Open Access Journals (Sweden)

S.A. Kanzler

2011-11-01

Full Text Available This study examined the food intake changes evoked by intracerebroventricular (icv injection of a selective agonist (BRL37344, 2 and 20 nmol or antagonist (SR59230A, 10 and 50 nmol of β3-adrenergic receptors in 24-h fasted rats (adult male Wistar rats, 200-350 g, N = 6/treatment. The animals were also pretreated with saline icv (SAL or SR59230A (50 nmol followed by BRL37344 (20 nmol or SAL in order to determine the selectivity of the effects evoked by BRL37344 on food intake or the selectivity of the effects evoked by SR59230A on risk assessment (RA behavior. The highest dose of BRL37344 (N = 7 decreased food intake 1 h after the treatment (6.4 ± 0.5 g in SAL-treated vs 4.2 ± 0.8 g in drug-treated rats. While both doses of SR59230A failed to affect food intake (5.1 ± 1.1 g for 10 nmol and 6.0 ± 1.8 g for 50 nmol, this treatment reduced the RA frequency (number/30 min (4 ± 2 for SAL-treated vs 1 ± 1 for 10 nmol and 0.5 ± 1 for 50 nmol SR59230A-treated rats, an ethological parameter related to anxiety. While pretreatment with SR59230A (7.0 ± 0.5 g abolished the hypophagia induced by BRL37344 (3.6 ± 0.9 g, BRL37344 suppressed the reduction in RA frequency caused by SR59230A. These results show that the hypophagia caused by BRL37344 is selectively mediated by β3-adrenergic receptors within the central nervous system. Moreover, they suggest the involvement of these receptors in the control of anxiety.

Cocaine Disrupts Histamine H3 Receptor Modulation of Dopamine D1 Receptor Signaling: σ1-D1-H3 Receptor Complexes as Key Targets for Reducing Cocaine's Effects

Science.gov (United States)

Moreno, Estefanía; Moreno-Delgado, David; Navarro, Gemma; Hoffmann, Hanne M.; Fuentes, Silvia; Rosell-Vilar, Santi; Gasperini, Paola; Rodríguez-Ruiz, Mar; Medrano, Mireia; Mallol, Josefa; Cortés, Antoni; Casadó, Vicent; Lluís, Carme; Ferré, Sergi; Ortiz, Jordi; Canela, Enric

2014-01-01

The general effects of cocaine are not well understood at the molecular level. What is known is that the dopamine D1 receptor plays an important role. Here we show that a key mechanism may be cocaine's blockade of the histamine H3 receptor-mediated inhibition of D1 receptor function. This blockade requires the σ1 receptor and occurs upon cocaine binding to σ1-D1-H3 receptor complexes. The cocaine-mediated disruption leaves an uninhibited D1 receptor that activates Gs, freely recruits β-arrestin, increases p-ERK 1/2 levels, and induces cell death when over activated. Using in vitro assays with transfected cells and in ex vivo experiments using both rats acutely treated or self-administered with cocaine along with mice depleted of σ1 receptor, we show that blockade of σ1 receptor by an antagonist restores the protective H3 receptor-mediated brake on D1 receptor signaling and prevents the cell death from elevated D1 receptor signaling. These findings suggest that a combination therapy of σ1R antagonists with H3 receptor agonists could serve to reduce some effects of cocaine. PMID:24599455

Cannabinoid receptor CB2 modulates axon guidance

DEFF Research Database (Denmark)

Duff, Gabriel; Argaw, Anteneh; Cecyre, Bruno

2013-01-01

on axon guidance. These effects are specific to CB2R since no changes were observed in mice where the gene coding for this receptor was altered (cnr2 (-/-)). The CB2R induced morphological changes observed at the growth cone are PKA dependent and require the presence of the netrin-1 receptor, Deleted...... CB2R's implication in retinothalamic development. Overall, this study demonstrates that the contribution of endocannabinoids to brain development is not solely mediated by CB1R, but also involves CB2R....

Receptor studies in biological psychiatry

International Nuclear Information System (INIS)

Fujiwara, Yutaka

1992-01-01

Recent advances in the pharmacological treatment of endogenous psychosis have led to the development of biological studies in psychiatry. Studies on neurotransmitter receptors were reviewed in order to apply positron-emission tomograph (PET) for biological psychiatry. The dopamine (DA) hypothesis for schizophrenia was advanced on the basis of the observed effects of neuroleptics and methamphetamine, and DA(D 2 ) receptor supersensitivity measured by PET and receptor binding in the schizophrenic brain. The clinical potencies of neuroleptics for schizophrenia were correlated with their abilities to inhibit the D 2 receptor, and not other receptors. The σ receptor was expected to be a site of antipsychotic action. However, the potency of drugs action on it was not correlated with clinical efficacy. Haloperidol binds with high affinity to the σ receptor, which may mediate acute dystonia, an extrapyramidal side effect of neuroleptics. Behavioral and neurochemical changes induced by methamphetamine treatment were studied as an animal model of schizophrenia, and both a decrease of D 2 receptor density and an increase of DA release were detected. The monoamine hypothesis for manic-depressive psychosis was advanced on the basis of the effect of reserpine, monoamine oxidase inhibitor and antidepressants. 3 H-clonidine binding sites were increased in platelet membranes of depressive patients, 3 H-imipramine binding sites were decreased. The GABA A receptor is the target site for the action of anxiolytics and antiepileptics such as benzodiazepines and barbiturates. Recent developments in molecular biology techniques have revealed the structure of receptor proteins, which are classified into two receptor families, the G-protein coupled type (D 2 ) and the ion-channel type (GABA A ). (J.P.N.)

Arrestin scaffolds NHERF1 to the P2Y12 receptor to regulate receptor internalization.

Science.gov (United States)

Nisar, Shaista P; Cunningham, Margaret; Saxena, Kunal; Pope, Robert J; Kelly, Eamonn; Mundell, Stuart J

2012-07-13

We have recently shown in a patient with mild bleeding that the PDZ-binding motif of the platelet G protein-coupled P2Y(12) receptor (P2Y(12)R) is required for effective receptor traffic in human platelets. In this study we show for the first time that the PDZ motif-binding protein NHERF1 exerts a major role in potentiating G protein-coupled receptor (GPCR) internalization. NHERF1 interacts with the C-tail of the P2Y(12)R and unlike many other GPCRs, NHERF1 interaction is required for effective P2Y(12)R internalization. In vitro and prior to agonist stimulation P2Y(12)R/NHERF1 interaction requires the intact PDZ binding motif of this receptor. Interestingly on receptor stimulation NHERF1 no longer interacts directly with the receptor but instead binds to the receptor via the endocytic scaffolding protein arrestin. These findings suggest a novel model by which arrestin can serve as an adaptor to promote NHERF1 interaction with a GPCR to facilitate effective NHERF1-dependent receptor internalization.

Risperidone treatment increases CB1 receptor binding in rat brain

DEFF Research Database (Denmark)

Secher, Anna; Husum, Henriette; Holst, Birgitte

2010-01-01

, the ghrelin receptor, neuropeptide Y, adiponectin and proopiomelanocortin. We investigated whether the expression of these factors was affected in rats chronically treated with the antipsychotic risperidone. METHODS: Male Sprague-Dawley rats were treated with risperidone (1.0 mg/kg/day) or vehicle (20...... showed that risperidone treatment altered CB(1) receptor binding in the rat brain. Risperidone-induced adiposity and metabolic dysfunction in the clinic may be explained by increased CB(1) receptor density in brain regions involved in appetite and regulation of metabolic function....

A candidate pheromone receptor and two odorant receptors of the hawkmoth Manduca sexta.

Science.gov (United States)

Patch, Harland M; Velarde, Rodrigo A; Walden, Kimberly K O; Robertson, Hugh M

2009-05-01

In this study, we cloned and characterized three Manduca sexta odorant receptors (ORs). One receptor is a putative pheromone receptor expressed exclusively in a cell associated with male-specific type-I trichoid sensilla. We describe the results of real-time PCR (RT-PCR) and quantitative real-time PCR (qRT-PCR) experiments that show MsextaOR1 is expressed only in male antennae. In situ hybridization labels a single cell associated with type-1 trichoid sensilla, which houses two neurons that have been previously determined to respond to the major components of the pheromone blend. The second receptor, MsextaOR2, was discovered using degenerate primers designed to conserved motifs of a unique group ORs that share as much as 88% identity. Comparison of RT-PCR, qRT-PCR, and in situ hybridization results with those of ORs in the Drosophila melanogaster Or83b subfamily shows a strong sequence and expression pattern similarity. The third receptor, MsextaOR3, was found by 5'-end sequencing of a normalized and subtracted cDNA library from male M. sexta antennae. RT-PCR and qRT-PCR show that this receptor is expressed only in male and female antennae. These are the first ORs, including a putative pheromone receptor, to be described from M. sexta.

Involvement of AMPA receptors in the antidepressant-like effects of dextromethorphan in mice.

Science.gov (United States)

Nguyen, Linda; Matsumoto, Rae R

2015-12-15

Dextromethorphan (DM) is an antitussive with rapid acting antidepressant potential based on pharmacodynamic similarities to ketamine. Building upon our previous finding that DM produces antidepressant-like effects in the mouse forced swim test (FST), the present study aimed to establish the antidepressant-like actions of DM in the tail suspension test (TST), another well-established model predictive of antidepressant efficacy. Additionally, using the TST and FST, we investigated the role of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors in the antidepressant-like properties of DM because accumulating evidence suggests that AMPA receptors play an important role in the pathophysiology of depression and may contribute to the efficacy of antidepressant medications, including that of ketamine. We found that DM displays antidepressant-like effects in the TST similar to the conventional and fast acting antidepressants characterized by imipramine and ketamine, respectively. Moreover, decreasing the first-pass metabolism of DM by concomitant administration of quinidine (CYP2D6 inhibitor) potentiated antidepressant-like actions, implying DM itself has antidepressant efficacy. Finally, in both the TST and FST, pretreatment with the AMPA receptor antagonist NBQX (2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide) significantly attenuated the antidepressant-like behavior elicited by DM. Together, the data show that DM exerts antidepressant-like actions through AMPA receptors, further suggesting DM may act as a safe and effective fast acting antidepressant drug. Copyright © 2015 Elsevier B.V. All rights reserved.

Structure and affinity of two bicyclic glutamate analogues at AMPA and kainate receptors

DEFF Research Database (Denmark)

Møllerud, Stine; Pinto, Andrea; Marconi, Laura

2017-01-01

Ionotropic glutamate receptors (iGluRs) are involved in most of the fast excitatory synaptic transmission in the central nervous system. These receptors are important for learning and memory formation, but are also involved in the development of diseases such as Alzheimer’s disease, epilepsy...

Toward engineering intra-receptor interactions into bis(crown ethers).

Science.gov (United States)

Krause, Martin R; Kubik, Stefan

2012-03-01

A synthetic receptor was designed in which cooperative binding of two crown ether moieties to an alkali metal ion simultaneously causes two hydrophobic substituents not involved in direct host-guest interactions to converge. Hydrophobic interactions between these substituents can be expected to contribute to the overall complex stability. Independent binding studies involving two diastereoisomers of this bis(crown ether), one in which intra-receptor interactions between the substituents are potentially possible and one in which they are not, using isothermal titration calorimetry showed that both isomers bind potassium ions in different solvent mixtures with the same overall affinity. Profound differences were observed for each isomer, however, in the enthalpies and entropies of binding, which are consistent with intra-receptor interactions in one compound. These interactions are counteracted by enthalpy-entropy compensation so that no overall improvement in cation affinity could be observed.

The involvement of the sigma-1 receptor in neurodegeneration and neurorestoration.

Science.gov (United States)

Ruscher, Karsten; Wieloch, Tadeusz

2015-01-01

The sigma-1 receptor (Sig-1R) is a single 25 kD polypeptide and a chaperone protein immersed in lipid rafts of the endoplasmic reticulum (ER) where it interacts with mitochondria at the mitochondria-associated ER membrane domain (MAM). Upon activation, the Sig-1R binds to the inositol trisphosphate receptor (IP3R), and modulates cellular calcium (Ca(2+)) homeostasis. Also, the activated Sig-1R modulates plasma membrane receptor and ion channel functions, and may regulate cellular excitability. Further, the Sig-1R promotes trafficking of lipids and proteins essential for neurotransmission, cell growth and motility. Activation of the Sig-1R provides neuroprotection and is neurorestorative in cellular and animal models of neurodegenerative diseases and brain ischaemia. Neuroprotection appears to be due to inhibition of cellular Ca(2+) toxicity and/or inflammation, and neurorestoration may include balancing abberant neurotransmission or stimulation of synaptogenesis, thus remodelling brain connectivity. Single nucleotide polymorphisms and mutations of the SIGMAR1 gene worsen outcome in Alzheimer's disease and myotrophic lateral sclerosis supporting a role of Sig-1R in neurodegenerative disease. The combined neuroprotective and neurorestorative actions of the Sig-1R, provide a broad therapeutic time window of Sig-1R agonists. The Sig-1R is therefore a strong therapeutic target for the development of new treatments for neurodegenerative diseases and stroke. Copyright © 2014 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.

Transcriptional targets shared by estrogen receptor- related receptors (ERRs) and estrogen receptor (ER) alpha, but not by ERbeta.

Science.gov (United States)

Vanacker, J M; Pettersson, K; Gustafsson, J A; Laudet, V

1999-01-01

The physiological activities of estrogens are thought to be mediated by specific nuclear receptors, ERalpha and ERbeta. However, certain tissues, such as the bone, that are highly responsive to estrogens only express a low level of these receptors. Starting from this apparent contradiction, we have evaluated the potentials of two related receptors ERRalpha and ERRbeta to intervene in estrogen signaling. ERalpha, ERRalpha and ERRbeta bind to and activate transcription through both the classical estrogen response element (ERE) and the SF-1 response element (SFRE). In contrast, ERbeta DNA-binding and transcriptional activity is restricted to the ERE. Accordingly, the osteopontin gene promoter is stimulated through SFRE sequences, by ERRalpha as well as by ERalpha, but not by ERbeta. Analysis of the cross-talk within the ER/ERR subgroup of nuclear receptors thus revealed common targets but also functional differences between the two ERs. PMID:10428965

Flavivirus Entry Receptors: An Update

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Manuel Perera-Lecoin

2013-12-01

Full Text Available Flaviviruses enter host cells by endocytosis initiated when the virus particles interact with cell surface receptors. The current model suggests that flaviviruses use at least two different sets of molecules for infectious entry: attachment factors that concentrate and/or recruit viruses on the cell surface and primary receptor(s that bind to virions and direct them to the endocytic pathway. Here, we present the currently available knowledge regarding the flavivirus receptors described so far with specific attention to C-type lectin receptors and the phosphatidylserine receptors, T-cell immunoglobulin and mucin domain (TIM and TYRO3, AXL and MER (TAM. Their role in flavivirus attachment and entry as well as their implication in the virus biology will be discussed in depth.

Cytotoxicity of synthetic cannabinoids on primary neuronal cells of the forebrain: the involvement of cannabinoid CB1 receptors and apoptotic cell death

International Nuclear Information System (INIS)

Tomiyama, Ken-ichi; Funada, Masahiko

2014-01-01

The abuse of herbal products containing synthetic cannabinoids has become an issue of public concern. The purpose of this paper was to evaluate the acute cytotoxicity of synthetic cannabinoids on mouse brain neuronal cells. Cytotoxicity induced by synthetic cannabinoid (CP-55,940, CP-47,497, CP-47,497-C8, HU-210, JWH-018, JWH-210, AM-2201, and MAM-2201) was examined using forebrain neuronal cultures. These synthetic cannabinoids induced cytotoxicity in the forebrain cultures in a concentration-dependent manner. The cytotoxicity was suppressed by preincubation with the selective CB 1 receptor antagonist AM251, but not with the selective CB 2 receptor antagonist AM630. Furthermore, annexin-V-positive cells were found among the treated forebrain cells. Synthetic cannabinoid treatment induced the activation of caspase-3, and preincubation with a caspase-3 inhibitor significantly suppressed the cytotoxicity. These synthetic cannabinoids induced apoptosis through a caspase-3-dependent mechanism in the forebrain cultures. Our results indicate that the cytotoxicity of synthetic cannabinoids towards primary neuronal cells is mediated by the CB 1 receptor, but not by the CB 2 receptor, and further suggest that caspase cascades may play an important role in the apoptosis induced by these synthetic cannabinoids. In conclusion, excessive synthetic cannabinoid abuse may present a serious acute health concern due to neuronal damage or deficits in the brain. - Highlights: • Synthetic cannabinoids (classical cannabinoids, non-classical cannabinoids, and aminoalkylindole derivatives) induce cytotoxicity in mouse forebrain cultures. • Synthetic cannabinoid-induced cytotoxicity towards forebrain cultures is mediated by the CB 1 receptor, but not by the CB 2 receptor, and involves caspase-dependent apoptosis. • A high concentration of synthetic cannabinoids may be toxic to neuronal cells that express CB 1 receptors

Regulation of G Protein-Coupled Receptors by Ubiquitination

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Kamila Skieterska

2017-04-01

Full Text Available G protein-coupled receptors (GPCRs comprise the largest family of membrane receptors that control many cellular processes and consequently often serve as drug targets. These receptors undergo a strict regulation by mechanisms such as internalization and desensitization, which are strongly influenced by posttranslational modifications. Ubiquitination is a posttranslational modification with a broad range of functions that is currently gaining increased appreciation as a regulator of GPCR activity. The role of ubiquitination in directing GPCRs for lysosomal degradation has already been well-established. Furthermore, this modification can also play a role in targeting membrane and endoplasmic reticulum-associated receptors to the proteasome. Most recently, ubiquitination was also shown to be involved in GPCR signaling. In this review, we present current knowledge on the molecular basis of GPCR regulation by ubiquitination, and highlight the importance of E3 ubiquitin ligases, deubiquitinating enzymes and β-arrestins. Finally, we discuss classical and newly-discovered functions of ubiquitination in controlling GPCR activity.

The putative imidazoline receptor agonist, harmane, promotes intracellular calcium mobilisation in pancreatic beta-cells.

Science.gov (United States)

Squires, Paul E; Hills, Claire E; Rogers, Gareth J; Garland, Patrick; Farley, Sophia R; Morgan, Noel G

2004-10-06

beta-Carbolines (including harmane and pinoline) stimulate insulin secretion by a mechanism that may involve interaction with imidazoline I(3)-receptors but which also appears to be mediated by actions that are additional to imidazoline receptor agonism. Using the MIN6 beta-cell line, we now show that both the imidazoline I(3)-receptor agonist, efaroxan, and the beta-carboline, harmane, directly elevate cytosolic Ca(2+) and increase insulin secretion but that these responses display different characteristics. In the case of efaroxan, the increase in cytosolic Ca(2+) was readily reversible, whereas, with harmane, the effect persisted beyond removal of the agonist and resulted in the development of a repetitive train of Ca(2+)-oscillations whose frequency, but not amplitude, was concentration-dependent. Initiation of the Ca(2+)-oscillations by harmane was independent of extracellular calcium but was sensitive to both dantrolene and high levels (20 mM) of caffeine, suggesting the involvement of ryanodine receptor-gated Ca(2+)-release. The expression of ryanodine receptor-1 and ryanodine receptor-2 mRNA in MIN6 cells was confirmed using reverse transcription-polymerase chain reaction (RT-PCR) and, since low concentrations of caffeine (1 mM) or thimerosal (10 microM) stimulated increases in [Ca(2+)](i), we conclude that ryanodine receptors are functional in these cells. Furthermore, the increase in insulin secretion induced by harmane was attenuated by dantrolene, consistent with the involvement of ryanodine receptors in mediating this response. By contrast, the smaller insulin secretory response to efaroxan was unaffected by dantrolene. Harmane-evoked changes in cytosolic Ca(2+) were maintained by nifedipine-sensitive Ca(2+)-influx, suggesting the involvement of L-type voltage-gated Ca(2+)-channels. Taken together, these data imply that harmane may interact with ryanodine receptors to generate sustained Ca(2+)-oscillations in pancreatic beta-cells and that this effect

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

Science.gov (United States)

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.

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.

Serotonin 5-HT4 receptors and forebrain cholinergic system: receptor expression in identified cell populations.

Science.gov (United States)

Peñas-Cazorla, Raúl; Vilaró, M Teresa

2015-11-01

Activation of serotonin 5-HT4 receptors has pro-cognitive effects on memory performance. The proposed underlying neurochemical mechanism is the enhancement of acetylcholine release in frontal cortex and hippocampus elicited by 5-HT4 agonists. Although 5-HT4 receptors are present in brain areas related to cognition, e.g., hippocampus and cortex, the cellular localization of the receptors that might modulate acetylcholine release is unknown at present. We have analyzed, using dual label in situ hybridization, the cellular localization of 5-HT4 receptor mRNA in identified neuronal populations of the rat basal forebrain, which is the source of the cholinergic innervation to cortex and hippocampus. 5-HT4 receptor mRNA was visualized with isotopically labeled oligonucleotide probes, whereas cholinergic, glutamatergic, GABAergic and parvalbumin-synthesizing neurons were identified with digoxigenin-labeled oligonucleotide probes. 5-HT4 receptor mRNA was not detected in the basal forebrain cholinergic cell population. In contrast, basal forebrain GABAergic, parvalbumin synthesizing, and glutamatergic cells contained 5-HT4 receptor mRNA. Hippocampal and cortical glutamatergic neurons also express this receptor. These results indicate that 5-HT4 receptors are not synthesized by cholinergic cells, and thus would be absent from cholinergic terminals. In contrast, several non-cholinergic cell populations within the basal forebrain and its target hippocampal and cortical areas express these receptors and are thus likely to mediate the enhancement of acetylcholine release elicited by 5-HT4 agonists.

Stargazin Modulation of AMPA Receptors

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Sana A. Shaikh

2016-10-01

Full Text Available Fast excitatory synaptic signaling in the mammalian brain is mediated by AMPA-type ionotropic glutamate receptors. In neurons, AMPA receptors co-assemble with auxiliary proteins, such as stargazin, which can markedly alter receptor trafficking and gating. Here, we used luminescence resonance energy transfer measurements to map distances between the full-length, functional AMPA receptor and stargazin expressed in HEK293 cells and to determine the ensemble structural changes in the receptor due to stargazin. In addition, we used single-molecule fluorescence resonance energy transfer to study the structural and conformational distribution of the receptor and how this distribution is affected by stargazin. Our nanopositioning data place stargazin below the AMPA receptor ligand-binding domain, where it is well poised to act as a scaffold to facilitate the long-range conformational selection observations seen in single-molecule experiments. These data support a model of stargazin acting to stabilize or select conformational states that favor activation.

Photo-antagonism of the GABAA receptor.

Science.gov (United States)

Mortensen, Martin; Iqbal, Favaad; Pandurangan, Arun P; Hannan, Saad; Huckvale, Rosemary; Topf, Maya; Baker, James R; Smart, Trevor G

2014-07-29

Neurotransmitter receptor trafficking is fundamentally important for synaptic transmission and neural network activity. GABAA receptors and inhibitory synapses are vital components of brain function, yet much of our knowledge regarding receptor mobility and function at inhibitory synapses is derived indirectly from using recombinant receptors, antibody-tagged native receptors and pharmacological treatments. Here we describe the use of a set of research tools that can irreversibly bind to and affect the function of recombinant and neuronal GABAA receptors following ultraviolet photoactivation. These compounds are based on the competitive antagonist gabazine and incorporate a variety of photoactive groups. By using site-directed mutagenesis and ligand-docking studies, they reveal new areas of the GABA binding site at the interface between receptor β and α subunits. These compounds enable the selected inactivation of native GABAA receptor populations providing new insight into the function of inhibitory synapses and extrasynaptic receptors in controlling neuronal excitation.

Scavenger receptors in homeostasis and immunity.

Science.gov (United States)

Canton, Johnathan; Neculai, Dante; Grinstein, Sergio

2013-09-01

Scavenger receptors were originally identified by their ability to recognize and to remove modified lipoproteins; however, it is now appreciated that they carry out a striking range of functions, including pathogen clearance, lipid transport, the transport of cargo within the cell and even functioning as taste receptors. The large repertoire of ligands recognized by scavenger receptors and their broad range of functions are not only due to the wide range of receptors that constitute this family but also to their ability to partner with various co-receptors. The ability of individual scavenger receptors to associate with different co-receptors makes their responsiveness extremely versatile. This Review highlights recent insights into the structural features that determine the function of scavenger receptors and the emerging role that these receptors have in immune responses, notably in macrophage polarization and in the pathogenesis of diseases such as atherosclerosis and Alzheimer's disease.

Targeting of the tumor necrosis factor receptor superfamily for cancer immunotherapy

NARCIS (Netherlands)

Bremer, Edwin

2013-01-01

The tumor necrosis factor (TNF) ligand and cognate TNF receptor superfamilies constitute an important regulatory axis that is pivotal for immune homeostasis and correct execution of immune responses. TNF ligands and receptors are involved in diverse biological processes ranging from the selective

Aspects of dopamine and acetylcholine release induced by glutamate receptors; Aspectos das liberacoes de dopamina e acetilcolina mediadas por receptores de glutamato

Energy Technology Data Exchange (ETDEWEB)

Paes, Paulo Cesar de Arruda

2002-07-01

The basal ganglia play an important role in the motor control of rats and humans. This control involves different neurotransmitters and the mutual control of these key elements has been subject to several studies. In this work we determined the role of glutamate on the release of radioactively labelled dopamine and acetylcholine from chopped striatal tissue in vitro. The values of Effective Concentration 50% for glutamate, NMDA, kainic, quisqualic acids and AMPA on the release of dopamine and acetylcholine were obtained. The inhibitory effects of magnesium, tetrodotoxin, MK-801, AP5 and MCPG, as well as the effects of glycin were evaluated. The results suggested that dopamine is influenced by the NMDA type glutamate receptor while acetylcholine seems to be influenced by NMDA, kainate and AMPA receptors. Tetrodotoxin experiments suggested that kainate receptors are both present in cholinergic terminals and cell bodies while AMPA and NMDA receptors are preferentially distributed in cell bodies. Magnesium effectively blocked the NMDA stimulation and unexpectedly also AMPA- and quisqualate-induced acetylcholine release. The latter could not be blocked by MCPG ruling out the participation of methabotropic receptors. MK-801 also blocked NMDA-receptors. Results point out the importance of the glutamic acid control of dopamine and acetylcholine release in striatal tissue. (author)

Physiology and Emerging Biochemistry of the Glucagon-Like Peptide-1 Receptor

Directory of Open Access Journals (Sweden)

Francis S. Willard

2012-01-01

Full Text Available The glucagon-like peptide-1 (GLP-1 receptor is one of the best validated therapeutic targets for the treatment of type 2 diabetes mellitus (T2DM. Over several years, the accumulation of basic, translational, and clinical research helped define the physiologic roles of GLP-1 and its receptor in regulating glucose homeostasis and energy metabolism. These efforts provided much of the foundation for pharmaceutical development of the GLP-1 receptor peptide agonists, exenatide and liraglutide, as novel medicines for patients suffering from T2DM. Now, much attention is focused on better understanding the molecular mechanisms involved in ligand induced signaling of the GLP-1 receptor. For example, advancements in biophysical and structural biology techniques are being applied in attempts to more precisely determine ligand binding and receptor occupancy characteristics at the atomic level. These efforts should better inform three-dimensional modeling of the GLP-1 receptor that will help inspire more rational approaches to identify and optimize small molecule agonists or allosteric modulators targeting the GLP-1 receptor. This article reviews GLP-1 receptor physiology with an emphasis on GLP-1 induced signaling mechanisms in order to highlight new molecular strategies that help determine desired pharmacologic characteristics for guiding development of future nonpeptide GLP-1 receptor activators.

P2X4: A fast and sensitive purinergic receptor

Directory of Open Access Journals (Sweden)

Jaanus Suurväli

2017-10-01

Full Text Available Extracellular nucleotides have been recognized as important mediators of activation, triggering multiple responses via plasma membrane receptors known as P2 receptors. P2 receptors comprise P2X ionotropic receptors and G protein-coupled P2Y receptors. P2X receptors are expressed in many tissues, where they are involved in a number of functions including synaptic transmission, muscle contraction, platelet aggregation, inflammation, macrophage activation, differentiation and proliferation, neuropathic and inflammatory pain. P2X4 is one of the most sensitive purinergic receptors (at nanomolar ATP concentrations, about one thousand times more than the archetypal P2X7. P2X4 is widely expressed in central and peripheral neurons, in microglia, and also found in various epithelial tissues and endothelial cells. It localizes on the plasma membrane, but also in intracellular compartments. P2X4 is preferentially localized in lysosomes, where it is protected from proteolysis by its glycosylation. High ATP concentration in the lysosomes does not activate P2X4 at low pH; P2X4 gets activated by intra-lysosomal ATP only in its fully dissociated tetra-anionic form, when the pH increases to 7.4. Thus, P2X4 is functioning as a Ca2+-channel after the fusion of late endosomes and lysosomes. P2X4 modulates major neurotransmitter systems and regulates alcohol-induced responses in microglia. P2X4 is one of the key receptors mediating neuropathic pain. However, injury-induced upregulation of P2X4 expression is gender dependent and plays a key role in pain difference between males and females. P2X4 is also involved in inflammation. Extracellular ATP being a pro-inflammatory molecule, P2X4 can trigger inflammation in response to high ATP release. It is therefore involved in multiple pathologies, like post-ischemic inflammation, rheumatoid arthritis, airways inflammation in asthma, neurodegenerative diseases and even metabolic syndrome. Although P2X4 remains poorly

Central alpha2 adrenergic receptors in the rat cerebral cortex: repopulation kinetics and receptor reserve

International Nuclear Information System (INIS)

Adler, C.H.

1986-01-01

The alpha 2 adrenergic receptor subtype is thought to play a role in the mechanism of action of antidepressant and antihypertensive drugs. This thesis has attempted to shed light on the regulation of central alpha 2 adrenergic receptors in the rat cerebral cortex. Repopulation kinetics analysis allows for the determination of the rate of receptor production, rate constant of degradation, and half-life of the receptor. This analysis was carried out using both radioligand binding and functional receptor assays at various times following the irreversible inactivation of central alpha 2 adrenergic receptors by in vivo administration of N-ethoxycarbonyl-2-ethyoxy-1,2-dihydroquinoline (EEDQ). Both alpha 2 agonist and antagonist ligand binding sites recovered with a t/sub 1/2/ equal to approximately 4 days. The function of alpha 2 adrenergic autoreceptors, which inhibit stimulation-evoked release of 3 H-norepinephrine ( 3 H-NE) and alpha 2 adrenergic heteroreceptors which inhibit stimulation-evoked release of 3 H-serotonin ( 3 H-5-HT) were assayed. The t/sub 1/2/ for recovery of maximal autoreceptor and heteroreceptor function was 2.4 days and 4.6 days, respectively. The demonstration of a receptor reserve is critical to the interpretation of past and future studies of the alpha 2 adrenergic receptor since it demonstrates that: (1) alterations in the number of alpha 2 adrenergic receptor binding sites cannot be extrapolated to the actual function of the alpha 2 adrenergic receptor; and (2) alterations in the number of alpha 2 receptors is not necessarily accompanied by a change in the maximum function being studied, but may only result in shifting of the dose-response curve

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

Science.gov (United States)

Tsuji, Motonori; Shudo, Koichi; Kagechika, Hiroyuki

2017-03-01

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

Involvement of urokinase receptor in the cross-talk between human hematopoietic stem cells and bone marrow microenvironment

DEFF Research Database (Denmark)

Selleri, Carmine; Montuori, Nunzia; Salvati, Annamaria

2016-01-01

Hematopoietic stem cells (HSCs) reside in bone marrow (BM) and can be induced to mobilize into the circulation for transplantation. Homing and lodgement into BM of transplanted HSCs are the first critical steps in their engraftment and involve multiple interactions between HSCs and the BM...... Culture (LTC)-Initiating Cells (ICs) and in the release of clonogenic progenitors from LTCs of CD34+ HSCs. Further, suPAR increases adhesion and survival of CD34+ KG1 AML cells, whereas uPAR84-95 increases their proliferation.Thus, circulating DIIDIII-suPAR, strongly increased in HSC mobilization...... microenvironment.uPAR is a three domain receptor (DIDIIDIII) which binds urokinase, vitronectin, integrins. uPAR can be cleaved and shed from the cell surface generating full-length and cleaved soluble forms (suPAR and DIIDIII-suPAR). DIIDIII-suPAR can bind fMLF receptors through the SRSRY sequence (residues 88...

Interaction of epidermal growth factor receptors with the cytoskeleton is related to receptor clustering

NARCIS (Netherlands)

van Belzen, N.; Spaargaren, M.; Verkleij, A. J.; Boonstra, J.

1990-01-01

Recently it has been established that cytoskeleton-associated epidermal growth factor (EGF) receptors are predominantly of the high-affinity class and that EGF induces a recruitment of low-affinity receptors to the cytoskeleton. The nature of this EGF-induced receptor-cytoskeleton interaction,

Involvement of dopamine D1/D2 receptors on harmane-induced amnesia in the step-down passive avoidance test.

Science.gov (United States)

Nasehi, Mohammad; Piri, Morteza; Nouri, Maryam; Farzin, Davood; Nayer-Nouri, Touraj; Zarrindast, Mohammad Reza

2010-05-25

Ingestion of harmane and other alkaloids derived from plant Peganum harmala has been shown to elicit profound behavioural and toxic effects in humans, including hallucinations, excitation, feelings of elation, and euphoria. These alkaloids in the high doses can cause a toxic syndrome characterized by tremors and convulsions. Harmane has also been shown to act on a variety of receptor systems in the mammalian brain, including those for serotonin, dopamine and benzodiazepines. In animals, it has been reported to affect short and long term memory. In the present study, effects of dopamine D1 and D2 receptor antagonists on the harmane (HA)-induced amnesia and exploratory behaviors were examined in mice. One-trial step-down and hole-board paradigms were used for the assessment of memory retention and exploratory behaviors in adult male NMRI mice respectively. Intraperitoneal (i.p.) administration of HA (5 and 10 mg/kg) immediately after training decreased memory consolidation, while had no effect on anxiety-like behavior. Memory retrieval was not altered by 15- or 30 min pre-testing administration of the D1 (SCH23390, 0.025, 0.05 and 0.1 mg/kg) or D2 (sulpiride 12.5, 25 and 50 mg/kg) receptor antagonists, respectively. In contrast, SCH23390 (0.05 and 0.1 mg/kg) or sulpiride (25 and 50 mg/kg) pre-test administration fully reversed HA-induced impairment of memory consolidation. Finally, neither D1 nor D2 receptor blockade affected exploratory behaviors in the hole-board paradigm. Altogether, these findings strongly suggest an involvement of D1 and D2 receptors modulation in the HA-induced impairment of memory consolidation. Copyright 2010 Elsevier B.V. All rights reserved.

Toll-like receptors and NOD-like receptors in rheumatic diseases.

LENUS (Irish Health Repository)

McCormack, William J

2012-02-01

The past 10 years have seen the description of families of receptors that drive proinflammatory cytokine production in infection and tissue injury. Two major classes have been examined in the context of inflammatory joint disease--the Toll-like receptors (TLRs) and NOD-like receptors (NLRs). TLRs such as TLR2 and TLR4 are being implicated in the pathology of rheumatoid arthritis, ankylosing spondylitis, lyme arthritis and osteoarthritis. Nalp3 has been identified as a key NLR for IL-1beta production and has been shown to have a particular role in gout. These findings present new therapeutic opportunities, possibly allowing for the replacement of biologics with small molecule inhibitors.

Olfactory Receptor Database: a sensory chemoreceptor resource

OpenAIRE

Skoufos, Emmanouil; Marenco, Luis; Nadkarni, Prakash M.; Miller, Perry L.; Shepherd, Gordon M.

2000-01-01

The Olfactory Receptor Database (ORDB) is a WWW-accessible database that has been expanded from an olfactory receptor resource to a chemoreceptor resource. It stores data on six classes of G-protein-coupled sensory chemoreceptors: (i) olfactory receptor-like proteins, (ii) vomeronasal receptors, (iii) insect olfactory receptors, (iv) worm chemoreceptors, (v) taste papilla receptors and (vi) fungal pheromone receptors. A complementary database of the ligands of these receptors (OdorDB) has bee...

Molecular characterization of opioid receptors

Energy Technology Data Exchange (ETDEWEB)

Howard, A.D.

1986-01-01

The aim of this research was to purify and characterize active opioid receptors and elucidate molecular aspects of opioid receptor heterogeneity. Purification to apparent homogeneity of an opioid binding protein from bovine caudate was achieved by solubilization in the non-ionic detergent, digitonin, followed by sequential chromatography on the opiate affinity matrix, ..beta..-naltrexylethylenediamine-CH-Sepharose 4B, and on the lectine affinity matrix, wheat germ agglutinin-agarose. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) followed by autoradiography revealed that radioiodinated purified receptor gave a single band. Purified receptor preparations showed a specific activity of 12,000-15,000 fmol of opiate bound per mg of protein. Radioiodinated human beta-endorphin (/sup 125/I-beta-end/sub H/) was used as a probe to investigate the ligand binding subunits of mu and delta opioid receptors. /sup 125/I-beta-end/sub H/ was shown to bind to a variety of opioid receptor-containing tissues with high affinity and specificity with preference for mu and delta sites, and with little, if any, binding to kappa sites. Affinity crosslinking techniques were employed to covalently link /sup 125/I-beta-end/sub H/ to opioid receptors, utilizing derivatives of bis-succinimidyl esters that are bifunctional crosslinkers with specificities for amino and sulfhydryl groups. This, and competition experiments with high type-selective ligands, permitted the assignment of two labeled peptides to their receptor types, namely a peptide of M/sub r/ = 65,000 for mu receptors and one of M/sub r/ = 53,000 for delta receptors.

NR4A nuclear receptors are orphans but not lonesome.

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Kurakula, Kondababu; Koenis, Duco S; van Tiel, Claudia M; de Vries, Carlie J M

2014-11-01

The NR4A subfamily of nuclear receptors consists of three mammalian members: Nur77, Nurr1, and NOR-1. The NR4A receptors are involved in essential physiological processes such as adaptive and innate immune cell differentiation, metabolism and brain function. They act as transcription factors that directly modulate gene expression, but can also form trans-repressive complexes with other transcription factors. In contrast to steroid hormone nuclear receptors such as the estrogen receptor or the glucocorticoid receptor, no ligands have been described for the NR4A receptors. This lack of known ligands might be explained by the structure of the ligand-binding domain of NR4A receptors, which shows an active conformation and a ligand-binding pocket that is filled with bulky amino acid side-chains. Other mechanisms, such as transcriptional control, post-translational modifications and protein-protein interactions therefore seem to be more important in regulating the activity of the NR4A receptors. For Nur77, over 80 interacting proteins (the interactome) have been identified so far, and roughly half of these interactions has been studied in more detail. Although the NR4As show some overlap in interacting proteins, less information is available on the interactome of Nurr1 and NOR-1. Therefore, the present review will describe the current knowledge on the interactomes of all three NR4A nuclear receptors with emphasis on Nur77. Copyright © 2014 Elsevier B.V. All rights reserved.

NMDA Receptors in Glial Cells: Pending Questions.

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Dzamba, David; Honsa, Pavel; Anderova, Miroslava

2013-05-01

Glutamate receptors of the N-methyl-D-aspartate (NMDA) type are involved in many cognitive processes, including behavior, learning and synaptic plasticity. For a long time NMDA receptors were thought to be the privileged domain of neurons; however, discoveries of the last 25 years have demonstrated their active role in glial cells as well. Despite the large number of studies in the field, there are many unresolved questions connected with NMDA receptors in glia that are still a matter of debate. The main objective of this review is to shed light on these controversies by summarizing results from all relevant works concerning astrocytes, oligodendrocytes and polydendrocytes (also known as NG2 glial cells) in experimental animals, further extended by studies performed on human glia. The results are divided according to the study approach to enable a better comparison of how findings obtained at the mRNA level correspond with protein expression or functionality. Furthermore, special attention is focused on the NMDA receptor subunits present in the particular glial cell types, which give them special characteristics different from those of neurons - for example, the absence of Mg(2+) block and decreased Ca(2+) permeability. Since glial cells are implicated in important physiological and pathophysiological roles in the central nervous system (CNS), the last part of this review provides an overview of glial NMDA receptors with respect to ischemic brain injury.

Hydrostatic pressure and muscarinic receptors are involved in the release of inflammatory cytokines in human bladder smooth muscle cells.

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Liang, Zhou; Xin, Wei; Qiang, Liu; Xiang, Cai; Bang-Hua, Liao; Jin, Yang; De-Yi, Luo; Hong, Li; Kun-Jie, Wang

2017-06-01

Abnormal intravesical pressure results in a series of pathological changes. We investigated the effects of hydrostatic pressure and muscarinic receptors on the release of inflammatory cytokines in rat and human bladder smooth muscle cells (HBSMCs). Animal model of bladder outlet obstruction was induced by urethra ligation. HBSMCs were subjected to elevated hydrostatic pressure and/or acetylcholine (Ach). Macrophage infiltration in the bladder wall was determined by immunohistochemical staining. The expression of inflammatory genes was measured by RT-PCR, ELISA and immunofluorescence. In obstructed bladder, inflammatory genes and macrophage infiltration were remarkably induced. When HBSMCs were subjected to 200-300 cm H 2 O pressure for 2-24 h in vitro, the expressions of IL-6 and RANTES were significantly increased. Hydrostatic pressure promoted the protein levels of phospho-NFκB p65 and phospho-ERK1/2 as well as muscarinic receptors. Moreover, NFκB or ERK1/2 inhibitors suppressed pressure-induced inflammatory genes mRNA. When cells were treated with 1 μM acetylcholine for 6 h, a significant increase in IL-6 mRNA expression was detected. Acetylcholine also enhanced pressure-induced phospho-NFκB p65 and IL-6 protein expression. Additionally, pressure-induced IL-6 was partially suppressed by muscarinic receptors antagonists. Hydrostatic pressure and muscarinic receptors were involved in the secretion of inflammatory cytokines in HBSMCs, indicating a pro-inflammatory effect of the two factors in the pathological process of BOO. © 2016 Wiley Periodicals, Inc.

Taking two to tango: a role for ghrelin receptor heterodimerization in stress and reward.

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Schellekens, Harriët; Dinan, Timothy G; Cryan, John F

2013-08-30

The gut hormone, ghrelin, is the only known peripherally derived orexigenic signal. It activates its centrally expressed receptor, the growth hormone secretagogue receptor (GHS-R1a), to stimulate food intake. The ghrelin signaling system has recently been suggested to play a key role at the interface of homeostatic control of appetite and the hedonic aspects of food intake, as a critical role for ghrelin in dopaminergic mesolimbic circuits involved in reward signaling has emerged. Moreover, enhanced plasma ghrelin levels are associated with conditions of physiological stress, which may underline the drive to eat calorie-dense "comfort-foods" and signifies a role for ghrelin in stress-induced food reward behaviors. These complex and diverse functionalities of the ghrelinergic system are not yet fully elucidated and likely involve crosstalk with additional signaling systems. Interestingly, accumulating data over the last few years has shown the GHS-R1a receptor to dimerize with several additional G-protein coupled receptors (GPCRs) involved in appetite signaling and reward, including the GHS-R1b receptor, the melanocortin 3 receptor (MC3), dopamine receptors (D1 and D2), and more recently, the serotonin 2C receptor (5-HT2C). GHS-R1a dimerization was shown to affect downstream signaling and receptor trafficking suggesting a potential novel mechanism for fine-tuning GHS-R1a receptor mediated activity. This review summarizes ghrelin's role in food reward and stress and outlines the GHS-R1a dimer pairs identified to date. In addition, the downstream signaling and potential functional consequences of dimerization of the GHS-R1a receptor in appetite and stress-induced food reward behavior are discussed. The existence of multiple GHS-R1a heterodimers has important consequences for future pharmacotherapies as it significantly increases the pharmacological diversity of the GHS-R1a receptor and has the potential to enhance specificity of novel ghrelin-targeted drugs.

Taking Two to Tango: A Role for Ghrelin Receptor Heterodimerization in Stress and Reward

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Harriet eSchellekens

2013-08-01

Full Text Available The gut hormone, ghrelin, is the only known peripherally derived orexigenic signal. It activates its centrally expressed receptor, the growth hormone secretagogue receptor (GHS-R1a, to stimulate food intake. The ghrelin signalling system has recently been suggested to play a key role at the interface of homeostatic control of appetite and the hedonic aspects of food intake, as a critical role for ghrelin in dopaminergic mesolimbic circuits involved in reward signalling has emerged. Moreover, enhanced plasma ghrelin levels are associated with conditions of physiological stress, which may underline the drive to eat calorie-dense ‘comfort-foods’ and signifies a role for ghrelin in stress-induced food reward behaviours. These complex and diverse functionalities of the ghrelinergic system are not yet fully elucidated and likely involve crosstalk with additional signalling systems. Interestingly, accumulating data over the last few years has shown the GHS-R1a receptor to dimerize with several additional G-protein coupled receptors (GPCRs involved in appetite signalling and reward, including the GHS-R1b receptor, the melanocortin 3 receptor (MC3, dopamine receptors (D1 and D2, and more recently, the serotonin 2C receptor (5-HT2C. GHS-R1a dimerization was shown to affect downstream signalling and receptor trafficking suggesting a potential novel mechanism for fine-tuning GHS-R1a receptor mediated activity. This review summarizes ghrelin’s role in food reward and stress and outlines the GHS-R1a dimer pairs identified to date. In addition, the downstream signalling and potential functional consequences of dimerization of the GHS-R1a receptor in appetite and stress-induced food reward behaviour are discussed. The existence of multiple GHS-R1a heterodimers has important consequences for future pharmacotherapies as it significantly increases the pharmacological diversity of the GHS-R1a receptor and has the potential to enhance specificity of novel

Serotonin receptor activity is necessary for olfactory learning and memory in Drosophila melanogaster.

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Johnson, O; Becnel, J; Nichols, C D

2011-09-29

Learning and memory in the fruit fly, Drosophila melanogaster, is a complex behavior with many parallels to mammalian learning and memory. Although many neurotransmitters including acetylcholine, dopamine, glutamate, and GABA have previously been demonstrated to be involved in aversive olfactory learning and memory, the role of serotonin has not been well defined. Here, we present the first evidence of the involvement of individual serotonin receptors in olfactory learning and memory in the fly. We initially followed a pharmacological approach, utilizing serotonin receptor agonists and antagonists to demonstrate that all serotonin receptor families present in the fly are necessary for short-term learning and memory. Isobolographic analysis utilizing combinations of drugs revealed functional interactions are occurring between 5-HT(1A)-like and 5-HT(2), and 5-HT(2) and 5-HT(7) receptor circuits in mediating short-term learning and memory. Examination of long-term memory suggests that 5-HT(1A)-like receptors are necessary for consolidation and important for recall, 5-HT(2) receptors are important for consolidation and recall, and 5-HT(7) receptors are involved in all three phases. Importantly, we have validated our pharmacological results with genetic experiments and showed that hypomorph strains for 5-HT(2)Dro and 5-HT(1B)Dro receptors, as well as knockdown of 5-HT(7)Dro mRNA, significantly impair performance in short-term memory. Our data highlight the importance of the serotonin system and individual serotonin receptors to influence olfactory learning and memory in the fly, and position the fly as a model system to study the role of serotonin in cognitive processes relevant to mammalian CNS function. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

Lipid raft integrity affects GABAA receptor, but not NMDA receptor modulation by psychopharmacological compounds.

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Nothdurfter, Caroline; Tanasic, Sascha; Di Benedetto, Barbara; Uhr, Manfred; Wagner, Eva-Maria; Gilling, Kate E; Parsons, Chris G; Rein, Theo; Holsboer, Florian; Rupprecht, Rainer; Rammes, Gerhard

2013-07-01

Lipid rafts have been shown to play an important role for G-protein mediated signal transduction and the function of ligand-gated ion channels including their modulation by psychopharmacological compounds. In this study, we investigated the functional significance of the membrane distribution of NMDA and GABAA receptor subunits in relation to the accumulation of the tricyclic antidepressant desipramine (DMI) and the benzodiazepine diazepam (Diaz). In the presence of Triton X-100, which allowed proper separation of the lipid raft marker proteins caveolin-1 and flotillin-1 from the transferrin receptor, all receptor subunits were shifted to the non-raft fractions. In contrast, under detergent-free conditions, NMDA and GABAA receptor subunits were detected both in raft and non-raft fractions. Diaz was enriched in non-raft fractions without Triton X-100 in contrast to DMI, which preferentially accumulated in lipid rafts. Impairment of lipid raft integrity by methyl-β-cyclodextrine (MβCD)-induced cholesterol depletion did not change the inhibitory effect of DMI at the NMDA receptor, whereas it enhanced the potentiating effect of Diaz at the GABAA receptor at non-saturating concentrations of GABA. These results support the hypothesis that the interaction of benzodiazepines with the GABAA receptor likely occurs outside of lipid rafts while the antidepressant DMI acts on ionotropic receptors both within and outside these membrane microdomains.

RNAi screening of subtracted transcriptomes reveals tumor suppression by taurine-activated GABAA receptors involved in volume regulation

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van Nierop, Pim; Vormer, Tinke L.; Foijer, Floris; Verheij, Joanne; Lodder, Johannes C.; Andersen, Jesper B.; Mansvelder, Huibert D.; te Riele, Hein

2018-01-01

To identify coding and non-coding suppressor genes of anchorage-independent proliferation by efficient loss-of-function screening, we have developed a method for enzymatic production of low complexity shRNA libraries from subtracted transcriptomes. We produced and screened two LEGO (Low-complexity by Enrichment for Genes shut Off) shRNA libraries that were enriched for shRNA vectors targeting coding and non-coding polyadenylated transcripts that were reduced in transformed Mouse Embryonic Fibroblasts (MEFs). The LEGO shRNA libraries included ~25 shRNA vectors per transcript which limited off-target artifacts. Our method identified 79 coding and non-coding suppressor transcripts. We found that taurine-responsive GABAA receptor subunits, including GABRA5 and GABRB3, were induced during the arrest of non-transformed anchor-deprived MEFs and prevented anchorless proliferation. We show that taurine activates chloride currents through GABAA receptors on MEFs, causing seclusion of cell volume in large membrane protrusions. Volume seclusion from cells by taurine correlated with reduced proliferation and, conversely, suppression of this pathway allowed anchorage-independent proliferation. In human cholangiocarcinomas, we found that several proteins involved in taurine signaling via GABAA receptors were repressed. Low GABRA5 expression typified hyperproliferative tumors, and loss of taurine signaling correlated with reduced patient survival, suggesting this tumor suppressive mechanism operates in vivo. PMID:29787571

Interference by 2,3,7,8-tetrachlorodibenzo-p-dioxin with cultured mouse submandibular gland branching morphogenesis involves reduced epidermal growth factor receptor signaling

International Nuclear Information System (INIS)

Kiukkonen, Anu; Sahlberg, Carin; Partanen, Anna-Maija; Alaluusua, Satu; Pohjanvirta, Raimo; Tuomisto, Jouko; Lukinmaa, Pirjo-Liisa

2006-01-01

Toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to mouse embryonic teeth, sharing features of early development with salivary glands in common, involves enhanced apoptosis and depends on the expression of epidermal growth factor (EGF) receptor. EGF receptor signaling, on the other hand, is essential for salivary gland branching morphogenesis. To see if TCDD impairs salivary gland morphogenesis and if the impairment is associated with EGF receptor signaling, we cultured mouse (NMRI) E13 submandibular glands with TCDD or TCDD in combination with EGF or fibronectin (FN), both previously found to enhance branching morphogenesis. Explants were examined stereomicroscopically and processed to paraffin sections. TCDD exposure impaired epithelial branching and cleft formation, resulting in enlarged buds. The glands were smaller than normal. EGF and FN alone concentration-dependently stimulated or inhibited branching morphogenesis but when co-administered with TCDD, failed to compensate for its effect. TCDD induced cytochrome P4501A1 expression in the glandular epithelium, indicating activation of the aryl hydrocarbon receptor. TCDD somewhat increased epithelial apoptosis as observed by terminal deoxynucleotidyl transferase (TdT)-mediated nick end-labeling method but the increase could not be correlated with morphological changes. The frequency of proliferating cells was not altered. Corresponding to the reduced cleft sites in TCDD-exposed explants, FN immunoreactivity in the epithelium was reduced. The results show that TCDD, comparably with EGF and FN at morphogenesis-inhibiting concentrations, impaired salivary gland branching morphogenesis in vitro. Together with the failure of EGF and FN at morphogenesis-stimulating concentrations to compensate for the effect of TCDD this implies that TCDD toxicity to developing salivary gland involves reduced EGF receptor signaling

P2Y receptor-mediated transient relaxation of rat longitudinal ileum preparations involves phospholipase C activation, intracellular Ca(2+) release and SK channel activation.

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Mader, Felix; Krause, Ludwig; Tokay, Tursonjan; Hakenberg, Oliver W; Köhling, Rüdiger; Kirschstein, Timo

2016-05-01

Purinergic signaling plays a major role in the enteric nervous system, where it governs gut motility through a number of P2X and P2Y receptors. The aim of this study was to investigate the P2Y receptor-mediated motility in rat longitudinal ileum preparations. Ileum smooth muscle strips were prepared from rats, and fixed in an organ bath. Isometric contraction and relaxation responses of the muscle strips were measured with force transducers. Drugs were applied by adding of stock solutions to the organ bath to yield the individual final concentrations. Application of the non-hydrolyzable P2 receptor agonists α,β-Me-ATP or 2-Me-S-ADP (10, 100 μmol/L) dose-dependently elicited a transient relaxation response followed by a sustained contraction. The relaxation response was largely blocked by SK channel blockers apamin (500 nmol/L) and UCL1684 (10 μmol/L), PLC inhibitor U73122 (100 μmol/L), IP3 receptor blocker 2-APB (100 μmol/L) or sarcoendoplasmic Ca(2+) ATPase inhibitor thapsigargin (1 μmol/L), but not affected by atropine, NO synthase blocker L-NAME or tetrodotoxin. Furthermore, α,β-Me-ATP-induced relaxation was suppressed by P2Y1 receptor antagonist MRS2179 (50 μmol/L) or P2Y13 receptor antagonist MRS2211 (100 μmol/L), and was abolished by co-application of the two antagonists, whereas 2-Me-S-ADP-induced relaxation was abolished by P2Y6 receptor antagonist MRS2578 (50 μmol/L). In addition, P2Y1 receptor antagonist MRS2500 (1 μmol/L) not only abolished α,β-Me-ATP-induced relaxation, but also suppressed 2-Me-S-ADP-induced relaxation. P2Y receptor agonist-induced transient relaxation of rat ileum smooth muscle strips is mediated predominantly by P2Y1 receptor, but also by P2Y6 and P2Y13 receptors, and involves PLC, IP3, Ca(2+) release and SK channel activation, but is independent of acetylcholine and NO release.

An extrahepatic receptor-associated protein-sensitive mechanism is involved in the metabolism of triglyceride-rich lipoproteins

NARCIS (Netherlands)

Vlijmen, B.J.M. van; Rohlmann, A.; Page, S.T.; Bensadoun, A.; Bos, I.S.T.; Berkel, T.J.C. van; Havekes, L.M.; Herz, J.

1999-01-01

We have used adenovirus-mediated gene transfer in mice to investigate low density lipoprotein receptor (LDLR) and LDLR-related protein (LRP)- independent mechanisms that control the metabolism of chylomicron and very low density lipoprotein (VLDL) remnants in vivo. Overexpression of receptor-

3H-spiroperidol labels serotonin receptors in rat cerebral cortex and hippocampus

International Nuclear Information System (INIS)

Creese, I.; Snyder, S.H.

1978-01-01

It is found that in the cerebral cortex, butaclamol displaceable 3 H-spiroperidol binding labels both dopamine and serotonin receptors. In the hippocampus it is probable that 3 H-spiroperidol binding involves serotonin receptors exclusively. (Auth.)

Involvement of macrophage migration inhibitory factor and its receptor (CD74) in human breast cancer.

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Richard, Vincent; Kindt, Nadège; Decaestecker, Christine; Gabius, Hans-Joachim; Laurent, Guy; Noël, Jean-Christophe; Saussez, Sven

2014-08-01

Macrophage migration inhibitory factor (MIF) and its receptor CD74 appear to be involved in tumorigenesis. We evaluated, by immunohistochemical staining, the tissue expression and distribution of MIF and CD74 in serial sections of human invasive breast cancer tumor specimens. The serum MIF level was also determined in breast cancer patients. We showed a significant increase in serum MIF average levels in breast cancer patients compared to healthy individuals. MIF tissue expression, quantified by a modified Allred score, was strongly increased in carcinoma compared to tumor-free specimens, in the cancer cells and in the peritumoral stroma, with fibroblasts the most intensely stained. We did not find any significant correlation with histoprognostic factors, except for a significant inverse correlation between tumor size and MIF stromal positivity. CD74 staining was heterogeneous and significantly decreased in cancer cells but increased in the surrounding stroma, namely in lymphocytes, macrophages and vessel endothelium. There was no significant variation according to classical histoprognostic factors, except that CD74 stromal expression was significantly correlated with triple-negative receptor (TRN) status and the absence of estrogen receptors. In conclusion, our data support the concept of a functional role of MIF in human breast cancer. In addition to auto- and paracrine effects on cancer cells, MIF could contribute to shape the tumor microenvironment leading to immunomodulation and angiogenesis. Interfering with MIF effects in breast tumors in a therapeutic perspective remains an attractive but complex challenge. Level of co-expression of MIF and CD74 could be a surrogate marker for efficacy of anti-angiogenic drugs, particularly in TRN breast cancer tumor.

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.

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

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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

Delta opioid receptor on equine sperm cells: subcellular localization and involvement in sperm motility analyzed by computer assisted sperm analyzer (CASA

Directory of Open Access Journals (Sweden)

Lacalandra Giovanni M

2010-06-01

Full Text Available Abstract Background Opioid receptors and endogenous opioid peptides act not only in the control of nociceptive pathways, indeed several reports demonstrate the effects of opiates on sperm cell motility and morphology suggesting the importance of these receptors in the modulation of reproduction in mammals. In this study we investigated the expression of delta opioid receptors on equine spermatozoa by western blot/indirect immunofluorescence and its relationship with sperm cell physiology. Methods We analyzed viability, motility, capacitation, acrosome reaction and mitochondrial activity in the presence of naltrindole and DPDPE by means of a computer assisted sperm analyzer and a fluorescent confocal microscope. The evaluation of viability, capacitation and acrosome reaction was carried out by the double CTC/Hoechst staining, whereas mitochondrial activity was assessed by means of MitoTracker Orange dye. Results We showed that in equine sperm cells, delta opioid receptor is expressed as a doublet of 65 and 50 kDa molecular mass and is localized in the mid piece of tail; we also demonstrated that naltrindole, a delta opioid receptor antagonist, could be utilized in modulating several physiological parameters of the equine spermatozoon in a dose-dependent way. We also found that low concentrations of the antagonist increase sperm motility whereas high concentrations show the opposite effect. Moreover low concentrations hamper capacitation, acrosome reaction and viability even if the percentage of cells with active mitochondria seems to be increased; the opposite effect is exerted at high concentrations. We have also observed that the delta opioid receptor agonist DPDPE is scarcely involved in affecting the same parameters at the employed concentrations. Conclusions The results described in this paper add new important details in the comprehension of the mammalian sperm physiology and suggest new insights for improving reproduction and for

Evidence for Alpha Receptors in the Human Ureter

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Madeb, Ralph; Knopf, Joy; Golijanin, Dragan; Bourne, Patricia; Erturk, Erdal

2007-04-01

An immunohistochemical and western blot expression analysis of human ureters was performed in order to characterize the alpha-1-adrenergic receptor distribution along the length of the human ureteral wall. Mapping the distribution will assist in understanding the potential role alpha -1-adrenergic receptors and their subtype density might have in the pathophysiology of ureteral colic and stone passage. Patients diagnosed with renal cancer or bladder cancer undergoing nephrectomy, nephroureterectomy, or cystectomy had ureteral specimens taken from the proximal, mid, distal and tunneled ureter. Tissues were processed for fresh frozen examination and fixed in formalin. None of the ureteral specimens were involved with cancer. Serial histologic sections and immunohistochemical studies were performed using antibodies specific for alpha-1-adrenergic receptor subtypes (alpha 1a, alpha 1b, alpha 1d). The sections were examined under a light microscope and scored as positive or negative. In order to validate and quantify the alpha receptor subtypes along the human ureter. Western blotting techniques were applied. Human ureter stained positively for alpha -1-adrenergic receptors. Immunostaining appeared red, with intense reaction in the smooth muscle of the ureter and endothelium of the neighboring blood vessels. There was differential expression between all the receptors with the highest staining for alpha-1D subtype. The highest protein expression for all three subtypes was in the renal pelvis and decreased with advancement along the ureter to the distal ureter. At the distal ureter, there was marked increase in expression as one progressed towards the ureteral orifice. The same pattern of protein expression was exhibited for all three alpha -1-adrenergic receptor subtypes. We provide preliminary evidence for the ability to detect and quantify the alpha-1-receptor subtypes along the human ureter which to the best of our knowledge has never been done with

Hypocretin/Orexin regulation of dopamine signaling and cocaine self-administration is mediated predominantly by hypocretin receptor 1.

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Prince, Courtney D; Rau, Andrew R; Yorgason, Jordan T; España, Rodrigo A

2015-01-21

Extensive evidence suggests that the hypocretins/orexins influence cocaine reinforcement and dopamine signaling via actions at hypocretin receptor 1. By comparison, the involvement of hypocretin receptor 2 in reward and reinforcement processes has received relatively little attention. Thus, although there is some evidence that hypocretin receptor 2 regulates intake of some drugs of abuse, it is currently unclear to what extent hypocretin receptor 2 participates in the regulation of dopamine signaling or cocaine self-administration, particularly under high effort conditions. To address this, we examined the effects of hypocretin receptor 1, and/or hypocretin receptor 2 blockade on dopamine signaling and cocaine reinforcement. We used in vivo fast scan cyclic voltammetry to test the effects of hypocretin antagonists on dopamine signaling in the nucleus accumbens core and a progressive ratio schedule to examine the effects of these antagonists on cocaine self-administration. Results demonstrate that blockade of either hypocretin receptor 1 or both hypocretin receptor 1 and 2 significantly reduces the effects of cocaine on dopamine signaling and decreases the motivation to take cocaine. In contrast, blockade of hypocretin receptor 2 alone had no significant effects on dopamine signaling or self-administration. These findings suggest a differential involvement of the two hypocretin receptors, with hypocretin receptor 1 appearing to be more involved than hypocretin receptor 2 in the regulation of dopamine signaling and cocaine self-administration. When considered with the existing literature, these data support the hypothesis that hypocretins exert a permissive influence on dopamine signaling and motivated behavior via preferential actions on hypocretin receptor 1.

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 ...

Differences in kainate receptor involvement in hippocampal mossy fibre long-term potentiation depending on slice orientation.

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Sherwood, John L; Amici, Mascia; Dargan, Sheila L; Culley, Georgia R; Fitzjohn, Stephen M; Jane, David E; Collingridge, Graham L; Lodge, David; Bortolotto, Zuner A

2012-09-01

Long-term potentiation (LTP) is a well-established experimental model used to investigate the synaptic basis of learning and memory. LTP at mossy fibre - CA3 synapses in the hippocampus is unusual because it is normally N-methyl-d-aspartate (NMDA) receptor-independent. Instead it seems that the trigger for mossy fibre LTP involves kainate receptors (KARs). Although it is generally accepted that pre-synaptic KARs play an essential role in frequency facilitation and LTP, their subunit composition remains a matter of significant controversy. We have reported previously that both frequency facilitation and LTP can be blocked by selective antagonism of GluK1 (formerly GluR5/Glu(K5))-containing KARs, but other groups have failed to reproduce this effect. Moreover, data from receptor knockout and mRNA expression studies argue against a major role of GluK1, supporting a more central role for GluK2 (formerly GluR6/Glu(K6)). A potential reason underlying the controversy in the pharmacological experiments may reside in differences in the preparations used. Here we show differences in pharmacological sensitivity of synaptic plasticity at mossy fibre - CA3 synapses depend critically on slice orientation. In transverse slices, LTP of fEPSPs was invariably resistant to GluK1-selective antagonists whereas in parasagittal slices LTP was consistently blocked by GluK1-selective antagonists. In addition, there were pronounced differences in the magnitude of frequency facilitation and the sensitivity to the mGlu2/3 receptor agonist DCG-IV. Using anterograde labelling of granule cells we show that slices of both orientations possess intact mossy fibres and both large and small presynaptic boutons. Transverse slices have denser fibre tracts but a smaller proportion of giant mossy fibre boutons. These results further demonstrate a considerable heterogeneity in the functional properties of the mossy fibre projection. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

How calcium makes endocytic receptors attractive

DEFF Research Database (Denmark)

Andersen, Christian B F; Moestrup, Søren K

2014-01-01

of the receptor. Endosomal acidification and calcium efflux lead to the essential ligand-receptor affinity switch and separation. Recent data, including crystal structures of receptor-ligand complexes, now reveal how calcium, in different types of domain scaffolds, functions in a common way as a removable...... 'lynchpin' that stabilizes favorable positioning of ligand-attractive receptor residues. In addition to explaining how calcium depletion can cause ligand-receptor dissociation, the new data add further insight into how acidification contributes to dissociation through structural changes that affect...... the receptor calcium sites....

Blonanserin Ameliorates Phencyclidine-Induced Visual-Recognition Memory Deficits: the Complex Mechanism of Blonanserin Action Involving D3-5-HT2A and D1-NMDA Receptors in the mPFC

Science.gov (United States)

Hida, Hirotake; Mouri, Akihiro; Mori, Kentaro; Matsumoto, Yurie; Seki, Takeshi; Taniguchi, Masayuki; Yamada, Kiyofumi; Iwamoto, Kunihiro; Ozaki, Norio; Nabeshima, Toshitaka; Noda, Yukihiro

2015-01-01

Blonanserin differs from currently used serotonin 5-HT2A/dopamine-D2 receptor antagonists in that it exhibits higher affinity for dopamine-D2/3 receptors than for serotonin 5-HT2A receptors. We investigated the involvement of dopamine-D3 receptors in the effects of blonanserin on cognitive impairment in an animal model of schizophrenia. We also sought to elucidate the molecular mechanism underlying this involvement. Blonanserin, as well as olanzapine, significantly ameliorated phencyclidine (PCP)-induced impairment of visual-recognition memory, as demonstrated by the novel-object recognition test (NORT) and increased extracellular dopamine levels in the medial prefrontal cortex (mPFC). With blonanserin, both of these effects were antagonized by DOI (a serotonin 5-HT2A receptor agonist) and 7-OH-DPAT (a dopamine-D3 receptor agonist), whereas the effects of olanzapine were antagonized by DOI but not by 7-OH-DPAT. The ameliorating effect was also antagonized by SCH23390 (a dopamine-D1 receptor antagonist) and H-89 (a protein kinase A (PKA) inhibitor). Blonanserin significantly remediated the decrease in phosphorylation levels of PKA at Thr197 and of NR1 (an essential subunit of N-methyl-D-aspartate (NMDA) receptors) at Ser897 by PKA in the mPFC after a NORT training session in the PCP-administered mice. There were no differences in the levels of NR1 phosphorylated at Ser896 by PKC in any group. These results suggest that the ameliorating effect of blonanserin on PCP-induced cognitive impairment is associated with indirect functional stimulation of the dopamine-D1-PKA-NMDA receptor pathway following augmentation of dopaminergic neurotransmission due to inhibition of both dopamine-D3 and serotonin 5-HT2A receptors in the mPFC. PMID:25120077

Radiosequence analysis of the human progestin receptor charged with [3H]promegestone. A comparison with the glucocorticoid receptor

International Nuclear Information System (INIS)

Stroemstedt, P.E.B.; Berkenstam, A.; Joernvall, H.G.; Gustafsson, J.A.; Carlstedt-Duke, J.

1990-01-01

Partially purified preparations of the human progestin receptor and the human and rat glucocorticoid receptor proteins were covalently charged with the synthetic progestin, [ 3 H]promegestone, by photoaffinity labeling. After labeling, the denaturated protein was cleaved and the mixture of peptides subjected to radiosequence analysis as previously described for the rat glucocorticoid receptor protein. The radioactivity labels identified, corresponded to Met-759 and Met-909 after photoaffinity labeling of the human progestin receptor, and Met-622 and Cys-754 after labeling of the rat glucocorticoid receptor. The residues labeled in the glucocorticoid receptor are the same as those previously reported to bind triamcinolone actonide. The corresponding residues were also labeled in the human glucocorticoid receptor. Met-759 of the progestin receptor and Met-622 of the rat glucocorticoid receptor are positioned within a segment with an overall high degree of sequence similarity and are equivalent. However, Met-909 (progestin receptor) and Cys-754 (glucocorticoid receptor) do not occur within equivalent segments of the two proteins. Thus, although the two classes of steroid hormone share a common structure within the A-ring, there are subtle differences in their interaction with the two separate receptor proteins

Toll-like receptors in neonatal sepsis.

LENUS (Irish Health Repository)

O'Hare, Fiona M

2013-06-01

Toll-like receptors are vital transmembrane receptors that initiate the innate immune response to many micro-organisms. The discovery of these receptors has improved our understanding of host-pathogen interactions, and these receptors play an important role in the pathogenesis of multiple neonatal conditions such as sepsis and brain injury. Toll-like receptors, especially TLRs 2 and 4, are associated with necrotizing enterocolitis, periventricular leukomalacia and sepsis.

Human macrophage scavenger receptors: Primary structure, expression, and localization in atherosclerotic lesions

International Nuclear Information System (INIS)

Matsumoto, Akiyo; Itakura, Hiroshige; Kodama, Tatsuhiko; Naito, Makoto; Takahashi, Kiyoshi; Ikemoto, Shinji; Asaoka, Hitoshi; Hayakawa, Ikuho; Kanamori, Hiroshi; Takaku, Fumimaro; Aburatani, Hiroyuki; Suzuki, Hiroshi; Kobari, Yukage; Miyai, Tatsuya; Cohen, E.H.; Wydro, R.; Housman, D.E.

1990-01-01

Two types of cDNAs for human macrophage scavenger receptors were cloned from a cDNA library derived from the phorbol ester-treated human monocytic cell line THP-1. The type I and type II human scavenger receptors encoded by these cDNAs are homologous (73% and 71% amino acid identity) to their previously characterized bovine counterparts and consist of six domains: cytoplasmic (I), membrane-spanning (II), spacer (III), α-helical coiled-coil (IV), collagen-like (V), and a type-specific C-terminal (VI). The receptor gene is located on human chromosome 8. The human receptors expressed in CHO-K1 cells mediated endocytosis of modified low density lipoproteins. Two mRNAs, 4.0 and 3.2 kilobases, have been detected in human liver, placenta, and brain. Immunohistochemical studies using an anti-peptide antibody which recognizes human scavenger receptors indicated the presence of the scavenger receptors in the macrophages of lipid-rich atherosclerotic lesions, suggesting the involvement of scavenger receptors in atherogenesis

Labeled receptor ligands for spect

International Nuclear Information System (INIS)

Kung, H.F.

1989-01-01

Receptor specific imaging agents for single photon emission computed tomography (SPECT) can potentially be useful in the understanding of basic biochemistry and pharmacology of receptors. SPECT images may also provide tools for evaluation of density and binding kinetics of a specific receptor, information important for diagnosis and patient management. Basic requirements for receptor imaging agents are: (a) they are labeled with short-lived isotopes, (b) they show high selectivity and specific uptake, (c) they exhibit high target/background ratio, and (d) they can be modeled to obtain quantitative information. Several good examples of CNS receptor specific ligands labeled with I-123 have been developed, including iodoQNB, iodoestrogen iodobenzadiazepine, iodobenazepine, iodobenzamides for muscarinic, estrogen benzadiazepine, D-1 and D-2 dopamine receptors. With the advent of newer and faster SPECT imaging devices, it may be feasible to quantitate the receptor density by in vivo imaging techniques. These new brain imaging agents can provide unique diagnostic information, which may not be available through other imaging modalities, such as CT and MRI

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

Science.gov (United States)

Mizejewski, G J

2015-01-01

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

Role of desensitization and subunit expression for kainate receptor-mediated neurotoxicity in murine neocortical cultures

DEFF Research Database (Denmark)

Jensen, J B; Schousboe, A; Pickering, D S

1999-01-01

) toxicity mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors, and (3) toxicity that can be mediated by kainate receptors when desensitization of the receptors is blocked. The indirect action at NMDA receptors was discovered because (5R, 10S)-(+)-5-methyl-10,11-dihydro-5H...... nedioxy-5H-2,3-benzodiazepine (GYKI 53655), a selective AMPA receptor antagonist, abolished the remaining toxicity. These results indicated that kainate- and domoate-mediated toxicity involves both the NMDA and the AMPA receptors. Pretreatment of the cultures with concanavalin A to prevent desensitization...

Host factors that modify Plasmodium falciparum adhesion to endothelial receptors.

Science.gov (United States)

Mahamar, Almahamoudou; Attaher, Oumar; Swihart, Bruce; Barry, Amadou; Diarra, Bacary S; Kanoute, Moussa B; Cisse, Kadidia B; Dembele, Adama B; Keita, Sekouba; Gamain, Benoît; Gaoussou, Santara; Issiaka, Djibrilla; Dicko, Alassane; Duffy, Patrick E; Fried, Michal

2017-10-24

P. falciparum virulence is related to adhesion and sequestration of infected erythrocytes (IE) in deep vascular beds, but the endothelial receptors involved in severe malaria remain unclear. In the largest ever study of clinical isolates, we surveyed adhesion of freshly collected IE from children under 5 years of age in Mali to identify novel vascular receptors, and examined the effects of host age, hemoglobin type, blood group and severe malaria on levels of IE adhesion to a panel of endothelial receptors. Several novel molecules, including integrin α3β1, VE-cadherin, ICAM-2, junctional adhesion molecule-B (JAM-B), laminin, and cellular fibronectin, supported binding of IE from children. Severe malaria was not significantly associated with levels of IE adhesion to any of the 19 receptors. Hemoglobin AC, which reduces severe malaria risk, reduced IE binding to the receptors CD36 and integrin α5β1, while hemoglobin AS did not modify IE adhesion to any receptors. Blood groups A, AB and B significantly reduced IE binding to ICAM-1. Severe malaria risk varies with age, but age significantly impacted the level of IE binding to only a few receptors: IE binding to JAM-B decreased with age, while binding to CD36 and integrin α5β1 significantly increased with age.

GLUT2 and the incretin receptors are involved in glucose-induced incretin secretion

DEFF Research Database (Denmark)

Cani, Patrice D; Holst, Jens Juul; Drucker, Daniel J

2007-01-01

to those described for beta-cells, brain and hepatoportal sensors. We determined the role of GLUT2, GLP-1 or GIP receptors in glucose-induced incretins secretion, in the corresponding knockout mice. GLP-1 secretion was reduced in all mutant mice, while GIP secretion did not require GLUT2. Intestinal GLP-1...... content was reduced only in GIP and GLUT2 receptors knockout mice suggesting that this impairment could contribute to the phenotype. Intestinal GIP content was similar in all mice studied. Furthermore, the impaired incretins secretion was associated with a reduced glucose-stimulated insulin secretion...

Airborne fine particulate matter induces an upregulation of endothelin receptors on rat bronchi

International Nuclear Information System (INIS)

Wang, Rong; Xiao, Xue; Cao, Lei; Shen, Zhen-xing; Lei, Ying; Cao, Yong-xiao

2016-01-01

Airborne fine particulate matter (PM2.5) is a risk factor for respiratory diseases. However, little is known about the effects of PM2.5 on bronchi. The present study investigated the effect of airborne PM2.5 on rat bronchi and the underlying mechanisms. Isolated rat bronchial segments were cultured for 24 h. Endothelin (ET) receptor-mediated contractile responses were recorded using a wire myograph. The mRNA and protein expression levels of ET receptors were studied using quantitative real-time PCR, Western blotting, and immunohistochemistry. The results demonstrated that ET A and ET B receptor agonists induced remarkable contractile responses on fresh and cultured bronchial segments. PM2.5 (1.0 or 3.0 μg/ml) significantly enhanced ET A and ET B receptor-mediated contractile responses in bronchi with a markedly increased maximal contraction compared to the DMSO or fresh groups. PM2.5 increased the mRNA and protein expression levels of ET A and ET B receptors. U0126 (a MEK1/2 inhibitor) and SB203580 (a p38 inhibitor) significantly suppressed PM2.5-induced increases in ET B receptor-mediated contractile responses, mRNA and protein levels. SP600125 (a JNK inhibitor) and SB203580 significantly abrogated the PM2.5-induced enhancement of ET A receptor-mediated contraction and receptor expression. In conclusion, PM2.5 upregulates ET receptors in bronchi. ET B receptor upregulation is associated with MEK1/2 and p38 pathways, and the upregulation of ET A receptor is involved in JNK and p38 pathways. - Highlights: • Airborne PM2.5 induces bronchial hyperreactivity mediated with endothelin ET B and ET A receptors in rats. • PM2.5 increases mRNA and protein expressions of endothelin ET B and ET A receptors in bronchi. • The upregulation of ET B receptor is associated with MEK1/2 and p38 pathways. • The upregulation of ET A receptor is involved in JNK and p38 pathways. • The research provides novel understanding for PM2.5-associated respiratory diseases.

Cell surface receptors for signal transduction and ligand transport: a design principles study.

Directory of Open Access Journals (Sweden)

Harish Shankaran

2007-06-01

Full Text Available Receptors constitute the interface of cells to their external environment. These molecules bind specific ligands involved in multiple processes, such as signal transduction and nutrient transport. Although a variety of cell surface receptors undergo endocytosis, the systems-level design principles that govern the evolution of receptor trafficking dynamics are far from fully understood. We have constructed a generalized mathematical model of receptor-ligand binding and internalization to understand how receptor internalization dynamics encodes receptor function and regulation. A given signaling or transport receptor system represents a particular implementation of this module with a specific set of kinetic parameters. Parametric analysis of the response of receptor systems to ligand inputs reveals that receptor systems can be characterized as being: i avidity-controlled where the response control depends primarily on the extracellular ligand capture efficiency, ii consumption-controlled where the ability to internalize surface-bound ligand is the primary control parameter, and iii dual-sensitivity where both the avidity and consumption parameters are important. We show that the transferrin and low-density lipoprotein receptors are avidity-controlled, the vitellogenin receptor is consumption-controlled, and the epidermal growth factor receptor is a dual-sensitivity receptor. Significantly, we show that ligand-induced endocytosis is a mechanism to enhance the accuracy of signaling receptors rather than merely serving to attenuate signaling. Our analysis reveals that the location of a receptor system in the avidity-consumption parameter space can be used to understand both its function and its regulation.

Ionotropic crustacean olfactory receptors.

Directory of Open Access Journals (Sweden)

Elizabeth A Corey

Full Text Available The nature of the olfactory receptor in crustaceans, a major group of arthropods, has remained elusive. We report that spiny lobsters, Panulirus argus, express ionotropic receptors (IRs, the insect chemosensory variants of ionotropic glutamate receptors. Unlike insects IRs, which are expressed in a specific subset of olfactory cells, two lobster IR subunits are expressed in most, if not all, lobster olfactory receptor neurons (ORNs, as confirmed by antibody labeling and in situ hybridization. Ligand-specific ORN responses visualized by calcium imaging are consistent with a restricted expression pattern found for other potential subunits, suggesting that cell-specific expression of uncommon IR subunits determines the ligand sensitivity of individual cells. IRs are the only type of olfactory receptor that we have detected in spiny lobster olfactory tissue, suggesting that they likely mediate olfactory signaling. Given long-standing evidence for G protein-mediated signaling in activation of lobster ORNs, this finding raises the interesting specter that IRs act in concert with second messenger-mediated signaling.

Identification of steroid-binding and phosphorylated sites within the glucocorticoid receptor

International Nuclear Information System (INIS)

Smith, L.I.

1989-01-01

The primary goal of these studies was to localize the steroid-binding and phosphorylated sites of the glucocorticoid receptor. The synthetic steroid, dexamethasone 21-mesylate (DM) forms a covalent thioether bond via the sulfhydryl group of a cysteine residue in the receptor. To determine the covalent site of attachment of this ligand, receptors in WEHI-7 mouse thymoma cells were labeled with [ 3 H]DM and purified with a monoclonal antibody. The receptor was completely digested with trypsin and a single peptide covalently labeled with steroid identified by reversed-phase HPLC. This peptide was analyzed by automated Edman degradation to determine the location of the steroid-labeled residue. A similar analysis was performed on an overlapping peptide produced by Staphylococcus aureus protease digestion. Analysis of tryptic peptides from receptors labeled with both [ 3 H]DM and L-[ 35 S]methionine indicated that this peptide contained methionine. These analyses, coupled with the published amino acid sequence of the receptor, identified Cysteine-644 in the steroid-binding domain of the mouse glucocorticoid receptor as the residue involved in covalent steroid-binding. A synthetic peptide representing amino acids 640-650 of the mouse receptor was prepared and analyzed to confirm the identification. These biochemical studies represent a direct demonstration of an amino acid important in receptor function. It has been proposed that the receptor functions through a phosphorylation-dephosphorylation cycle to explain the dependence of hormone binding capacity upon cellular ATP. The glucocorticoid receptor has been shown to be a phosphoprotein. As an initial step to identifying a role of phosphorylation in receptor action, phosphorylated sites within the functional domains of the protein were identified

Hypoxia-inducible Lipid Droplet-associated (HILPDA) Is a Novel Peroxisome Proliferator-activated Receptor (PPAR) Target Involved in Hepatic Triglyceride Secretion

NARCIS (Netherlands)

Mattijsen, F.; Georgiadi, A.; Andasarie, T.; Szalowska, E.; Zota, A.; Krones-Herzig, A.; Kersten, A.H.

2014-01-01

Peroxisome proliferator-activated receptors (PPARs) play major roles in the regulation of hepatic lipid metabolism through the control of numerous genes involved in processes such as lipid uptake and fatty acid oxidation. Here we identify hypoxia-inducible lipid droplet-associated (Hilpda/Hig2) as a

Dynamics of the actin cytoskeleton mediates receptor cross talk: An emerging concept in tuning receptor signaling

Science.gov (United States)

Mattila, Pieta K.; Batista, Facundo D.

2016-01-01

Recent evidence implicates the actin cytoskeleton in the control of receptor signaling. This may be of particular importance in the context of immune receptors, such as the B cell receptor, where dysregulated signaling can result in autoimmunity and malignancy. Here, we discuss the role of the actin cytoskeleton in controlling receptor compartmentalization, dynamics, and clustering as a means to regulate receptor signaling through controlling the interactions with protein partners. We propose that the actin cytoskeleton is a point of integration for receptor cross talk through modulation of protein dynamics and clustering. We discuss the implication of this cross talk via the cytoskeleton for both ligand-induced and low-level constitutive (tonic) signaling necessary for immune cell survival. PMID:26833785

DMPD: Toll-like receptor 3: a link between toll-like receptor, interferon and viruses. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 15031527 Toll-like receptor 3: a link between toll-like receptor, interferon and virus... (.csml) Show Toll-like receptor 3: a link between toll-like receptor, interferon and viruses. PubmedID 1503...1527 Title Toll-like receptor 3: a link between toll-like receptor, interferon and virus

Dopamine D3 receptors regulate reconsolidation of cocaine memory.

Science.gov (United States)

Yan, Y; Kong, H; Wu, E J; Newman, A H; Xu, M

2013-06-25

Memories of learned associations between the rewarding properties of drugs of abuse and environmental cues contribute to craving and relapse in humans. Disruption of reconsolidation dampens or even erases previous memories. Dopamine (DA) mediates the acquisition of reward memory and drugs of abuse can pathologically change related neuronal circuits in the mesolimbic DA system. Previous studies showed that DA D3 receptors are involved in cocaine-conditioned place preference (CPP) and reinstatement of cocaine-seeking behavior. However, the role of D3 receptors in reconsolidation of cocaine-induced reward memory remains unclear. In the present study, we combined genetic and pharmacological approaches to investigate the role of D3 receptors in reconsolidation of cocaine-induced CPP. We found that the mutation of the D3 receptor gene weakened reconsolidation of cocaine-induced CPP in mice triggered by a 3-min (min) retrieval. Furthermore, treatment of a selective D3 receptor antagonist PG01037 immediately following the 3-min retrieval disrupted reconsolidation of cocaine-induced CPP in wild-type mice and such disruption remained at least 1 week after the 3-min retrieval. These results suggest that D3 receptors play a key role in reconsolidation of cocaine-induced CPP in mice, and that pharmacological blockade of these receptors may be therapeutic for the treatment of cocaine craving and relapse in clinical settings. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Involvement of CCR-2 chemokine receptor activation in ischemic preconditioning and postconditioning of brain in mice.

Science.gov (United States)

Rehni, Ashish K; Singh, Thakur Gurjeet

2012-10-01

The present study has been designed to investigate the potential role of CCR-2 chemokine receptor in ischemic preconditioning as well as postconditioning induced reversal of ischemia-reperfusion injury in mouse brain. Bilateral carotid artery occlusion of 17 min followed by reperfusion for 24h was employed in present study to produce ischemia and reperfusion induced cerebral injury in mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was evaluated using elevated plus-maze test and Morris water maze test. Rota rod test was employed to assess motor incoordination. Bilateral carotid artery occlusion followed by reperfusion produced cerebral infarction and impaired memory and motor co-ordination. Three preceding episodes of bilateral carotid artery occlusion for 1 min and reperfusion of 1 min were employed to elicit ischemic preconditioning of brain, while three episodes of bilateral carotid artery occlusion for 10s and reperfusion of 10s immediately after the completion of were employed to elicit ischemic postconditioning of brain. Both prior ischemic preconditioning as well as ischemic postconditioning immediately after global cerebral ischemia prevented markedly ischemia-reperfusion-induced cerebral injury as measured in terms of infarct size, loss of memory and motor coordination. RS 102895, a selective CCR-2 chemokine receptor antagonist, attenuated the neuroprotective effect of both the ischemic preconditioning as well as postconditioning. It is concluded that the neuroprotective effect of both ischemic preconditioning as well as ischemic postconditioning may involve the activation of CCR-2 chemokine receptors. Copyright © 2012 Elsevier Ltd. All rights reserved.

Homology-modeled ligand-binding domains of medaka estrogen receptors and androgen receptors: A model system for the study of reproduction

International Nuclear Information System (INIS)

Cui Jianzhou; Shen Xueyan; Yan Zuowei; Zhao Haobin; Nagahama, Yoshitaka

2009-01-01

Estrogen and androgen and their receptors play critical roles in physiological processes such as sexual differentiation and development. Using the available structural models for the human estrogen receptors alpha and beta and androgen receptor as templates, we designed in silico agonist and antagonist models of medaka estrogen receptor (meER) alpha, beta-1, and beta-2, and androgen receptor (meAR) alpha and beta. Using these models, we studied (1) the structural relationship between the ligand-binding domains (LBDs) of ERs and ARs of human and medaka, and (2) whether medaka ER and AR can be potential models for studying the ligand-binding activities of various agonists and antagonists of these receptors by docking analysis. A high level of conservation was observed between the sequences of the ligand-binding domains of meERα and huERα, meERβ1 and huERβ, meERβ2, and huERβ with 62.8%, 66.4%, and 65.1% identity, respectively. The sequence conservation between meARα and huAR, meARβ, and huAR was found with 70.1% and 61.0% of identity, respectively. Thirty-three selected endocrine disrupting chemicals (EDCs), including both agonists and antagonists, were docked into the LBD of ER and AR, and the corresponding docking score for medaka models and human templates were calculated. In order to confirm the conservation of the overall geometry and the binding pocket, the backbone root mean square deviation (RMSD) for Cα atoms was derived from the structure superposition of all 10 medaka homology models to the six human templates. Our results suggested conformational conservation between the ERs and ARs of medaka and human, Thus, medaka could be highly useful as a model system for studies involving estrogen and androgen interaction with their receptors.

Farnesoid X receptor, the bile acid sensing nuclear receptor, in liver regeneration

Directory of Open Access Journals (Sweden)

Guodong Li

2015-03-01

Full Text Available The liver is unique in regenerative potential, which could recover the lost mass and function after injury from ischemia and resection. The underlying molecular mechanisms of liver regeneration have been extensively studied in the past using the partial hepatectomy (PH model in rodents, where 2/3 PH is carried out by removing two lobes. The whole process of liver regeneration is complicated, orchestrated event involving a network of connected interactions, which still remain fully elusive. Bile acids (BAs are ligands of farnesoid X receptor (FXR, a nuclear receptor of ligand-activated transcription factor. FXR has been shown to be highly involved in liver regeneration. BAs and FXR not only interact with each other but also regulate various downstream targets independently during liver regeneration. Moreover, recent findings suggest that tissue-specific FXR also contributes to liver regeneration significantly. These novel findings suggest that FXR has much broader role than regulating BA, cholesterol, lipid and glucose metabolism. Therefore, these researches highlight FXR as an important pharmaceutical target for potential use of FXR ligands to regulate liver regeneration in clinic. This review focuses on the roles of BAs and FXR in liver regeneration and the current underlying molecular mechanisms which contribute to liver regeneration.

Andrographolide regulates epidermal growth factor receptor and transferrin receptor trafficking in epidermoid carcinoma (A-431) cells

Science.gov (United States)

Tan, Y; Chiow, KH; Huang, D; Wong, SH

2010-01-01

Background and purpose: Andrographolide is the active component of Andrographis paniculata, a plant used in both Indian and Chinese traditional medicine, and it has been demonstrated to induce apoptosis in different cancer cell lines. However, not much is known about how it may affect the key receptors implicated in cancer. Knowledge of how andrographolide affects receptor trafficking will allow us to better understand new mechanisms by which andrographolide may cause death in cancer cells. Experimental approach: We utilized the well-characterized epidermal growth factor receptor (EGFR) and transferrin receptor (TfR) expressed in epidermoid carcinoma (A-431) cells as a model to study the effect of andrographolide on receptor trafficking. Receptor distribution, the total number of receptors and surface receptors were analysed by immunofluorescence, Western blot as well as flow-cytometry respectively. Key results: Andrographolide treatment inhibited cell growth, down-regulated EGFRs on the cell surface and affected the degradation of EGFRs and TfRs. The EGFR was internalized into the cell at an increased rate, and accumulated in a compartment that co-localizes with the lysosomal-associated membrane protein in the late endosomes. Conclusion and implications: This study sheds light on how andrographolide may affect receptor trafficking by inhibiting receptor movement from the late endosomes to lysosomes. The down-regulation of EGFR from the cell surface also indicates a new mechanism by which andrographolide may induce cancer cell death. PMID:20233216

Inhibition of cisplatin-induced vomiting by selective 5-hydroxytryptamine M-receptor antagonism.

OpenAIRE

Miner, W. D.; Sanger, G. J.

1986-01-01

MDL 72222, the selective 5-hydroxytryptamine (5-HT) M-receptor antagonist, prevented or reduced cisplatin-induced emesis in ferrets. It is suggested that cisplatin-induced, and possibly other cytotoxic drug-induced vomiting may involve a 5-HT M-receptor mechanism.

In vivo studies of opiate receptors

International Nuclear Information System (INIS)

Frost, J.J.; Dannals, R.F.; Duelfer, T.; Burns, H.D.; Ravert, H.T.; Langstroem, B.; Balasubramanian, V.; Wagner, H.N. Jr.

1984-01-01

To study opiate receptors noninvasively in vivo using positron emission tomography, techniques for preferentially labeling opiate receptors in vivo can be used. The rate at which receptor-bound ligand clears from the brain in vivo can be predicted by measuring the equilibrium dissociation constant (KD) at 37 degrees C in the presence of 100 mM sodium chloride and 100 microM guanyl-5'-imidodiphosphate, the drug distribution coefficient, and the molecular weight. A suitable ligand for labeling opiate receptors in vivo is diprenorphine, which binds to mu, delta, and kappa receptors with approximately equal affinity in vitro. However, in vivo diprenorphine may bind predominantly to one opiate receptor subtype, possibly the mu receptor. To predict the affinity for binding to the opiate receptor, a Hansch correlation was determined between the 50% inhibitory concentration for a series of halogen-substituted fentanyl analogs and electronic, lipophilic, and steric parameters. Radiochemical methods for the synthesis of carbon-11-labeled diprenorphine and lofentanil are presented

In vivo studies of opiate receptors

Energy Technology Data Exchange (ETDEWEB)

Frost, J.J.; Dannals, R.F.; Duelfer, T.; Burns, H.D.; Ravert, H.T.; Langstroem, B.; Balasubramanian, V.; Wagner, H.N. Jr.

1984-01-01

To study opiate receptors noninvasively in vivo using positron emission tomography, techniques for preferentially labeling opiate receptors in vivo can be used. The rate at which receptor-bound ligand clears from the brain in vivo can be predicted by measuring the equilibrium dissociation constant (KD) at 37 degrees C in the presence of 100 mM sodium chloride and 100 microM guanyl-5'-imidodiphosphate, the drug distribution coefficient, and the molecular weight. A suitable ligand for labeling opiate receptors in vivo is diprenorphine, which binds to mu, delta, and kappa receptors with approximately equal affinity in vitro. However, in vivo diprenorphine may bind predominantly to one opiate receptor subtype, possibly the mu receptor. To predict the affinity for binding to the opiate receptor, a Hansch correlation was determined between the 50% inhibitory concentration for a series of halogen-substituted fentanyl analogs and electronic, lipophilic, and steric parameters. Radiochemical methods for the synthesis of carbon-11-labeled diprenorphine and lofentanil are presented.

Beta 2-adrenergic receptors are colocalized and coregulated with whisker barrels in rat somatosensory cortex

International Nuclear Information System (INIS)

Vos, P.; Kaufmann, D.; Hand, P.J.; Wolfe, B.B.

1990-01-01

Autoradiography has been used to visualize independently the subtypes of beta-adrenergic receptors in rat somatosensory cortex. Beta 2-adrenergic receptors, but not beta 1-adrenergic receptors colocalize with whisker barrels in this tissue. Thus, each whisker sends a specific multisynaptic pathway to the somatosensory cortex that can be histochemically visualized and only one subtype of beta-adrenergic receptor is specifically associated with this cortical representation. Additionally, neonatal lesion of any or all of the whisker follicles results in loss of the corresponding barrel(s) as shown by histochemical markers. This loss is paralleled by a similar loss in the organization of beta 2-adrenergic receptors in the somatosensory cortex. Other results indicate that these beta 2-adrenergic receptors are not involved in moment-to-moment signal transmission in this pathway and, additionally, are not involved in a gross way in the development of whisker-barrel array

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

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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.

Cytotoxicity of synthetic cannabinoids on primary neuronal cells of the forebrain: the involvement of cannabinoid CB{sub 1} receptors and apoptotic cell death

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Tomiyama, Ken-ichi; Funada, Masahiko, E-mail: mfunada@ncnp.go.jp

2014-01-01

The abuse of herbal products containing synthetic cannabinoids has become an issue of public concern. The purpose of this paper was to evaluate the acute cytotoxicity of synthetic cannabinoids on mouse brain neuronal cells. Cytotoxicity induced by synthetic cannabinoid (CP-55,940, CP-47,497, CP-47,497-C8, HU-210, JWH-018, JWH-210, AM-2201, and MAM-2201) was examined using forebrain neuronal cultures. These synthetic cannabinoids induced cytotoxicity in the forebrain cultures in a concentration-dependent manner. The cytotoxicity was suppressed by preincubation with the selective CB{sub 1} receptor antagonist AM251, but not with the selective CB{sub 2} receptor antagonist AM630. Furthermore, annexin-V-positive cells were found among the treated forebrain cells. Synthetic cannabinoid treatment induced the activation of caspase-3, and preincubation with a caspase-3 inhibitor significantly suppressed the cytotoxicity. These synthetic cannabinoids induced apoptosis through a caspase-3-dependent mechanism in the forebrain cultures. Our results indicate that the cytotoxicity of synthetic cannabinoids towards primary neuronal cells is mediated by the CB{sub 1} receptor, but not by the CB{sub 2} receptor, and further suggest that caspase cascades may play an important role in the apoptosis induced by these synthetic cannabinoids. In conclusion, excessive synthetic cannabinoid abuse may present a serious acute health concern due to neuronal damage or deficits in the brain. - Highlights: • Synthetic cannabinoids (classical cannabinoids, non-classical cannabinoids, and aminoalkylindole derivatives) induce cytotoxicity in mouse forebrain cultures. • Synthetic cannabinoid-induced cytotoxicity towards forebrain cultures is mediated by the CB{sub 1} receptor, but not by the CB{sub 2} receptor, and involves caspase-dependent apoptosis. • A high concentration of synthetic cannabinoids may be toxic to neuronal cells that express CB{sub 1} receptors.

A Review on Ubiquitination of Neurotrophin Receptors: Facts and Perspectives

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Sánchez-Sánchez, Julia; Arévalo, Juan Carlos

2017-01-01

Ubiquitination is a reversible post-translational modification involved in a plethora of different physiological functions. Among the substrates that are ubiquitinated, neurotrophin receptors (TrkA, TrkB, TrkC, and p75NTR) have been studied recently. TrkA is the most studied receptor in terms of its ubiquitination, and different E3 ubiquitin ligases and deubiquitinases have been implicated in its ubiquitination, whereas not much is known about the other neurotrophin receptors aside from their ubiquitination. Additional studies are needed that focus on the ubiquitination of TrkB, TrkC, and p75NTR in order to further understand the role of ubiquitination in their physiological and pathological functions. Here we review what is currently known regarding the ubiquitination of neurotrophin receptors and its physiological and pathological relevance. PMID:28335430

Characterization of melanocortin receptor ligands on cloned brain melanocortin receptors and on grooming behavior in the rat

NARCIS (Netherlands)

Gispen, W.H.; Adan, R.A.H.; Szklarczyk, A.W.; Oosterom, J.; Brakkee, J.H.; Nijenhuis, W.A.; Schaaper, W.M.; Meloen, R.H.

1999-01-01

Since the melanocortin MC3 and melanocortin MC4 receptors are the main melanocortin receptor subtypes expressed in rat brain, we characterized the activity and affinity of nine melanocortin receptor ligands using these receptors in vitro, as well as their activity in a well-defined

Chemokine Receptor-Specific Antibodies in Cancer Immunotherapy: Achievements and Challenges

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Vela, Maria; Aris, Mariana; Llorente, Mercedes; Garcia-Sanz, Jose A.; Kremer, Leonor

2015-01-01

The 1990s brought a burst of information regarding the structure, expression pattern, and role in leukocyte migration and adhesion of chemokines and their receptors. At that time, the FDA approved the first therapeutic antibodies for cancer treatment. A few years later, it was reported that the chemokine receptors CXCR4 and CCR7 were involved on directing metastases to liver, lung, bone marrow, or lymph nodes, and the over-expression of CCR4, CCR6, and CCR9 by certain tumors. The possibility of inhibiting the interaction of chemokine receptors present on the surface of tumor cells with their ligands emerged as a new therapeutic approach. Therefore, many research groups and companies began to develop small molecule antagonists and specific antibodies, aiming to neutralize signaling from these receptors. Despite great expectations, so far, only one anti-chemokine receptor antibody has been approved for its clinical use, mogamulizumab, an anti-CCR4 antibody, granted in Japan to treat refractory adult T-cell leukemia and lymphoma. Here, we review the main achievements obtained with anti-chemokine receptor antibodies for cancer immunotherapy, including discovery and clinical studies, proposed mechanisms of action, and therapeutic applications. PMID:25688243

Isolation and characterization of the inositol trisphosphate receptor from smooth muscle

International Nuclear Information System (INIS)

Chadwick, C.C.; Saito, A.; Fleischer, S.

1990-01-01

The release of Ca 2+ from internal stores is requisite to muscle contraction. In skeletal muscle and heart, the Ca 2+ release channels (ryanodine receptor) of sarcoplasmic reticulum, involved in excitation-contraction coupling, have recently been isolated and characterized. In smooth muscle, inositol 1,4,5-trisphosphate (IP 3 ) is believed to mobilize Ca 2+ from internal stores and thereby modulate contraction. The authors describe the isolation of an IP 3 receptor from smooth muscle. Bovine aorta smooth muscle microsomes were solubilized with 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate, and the IP 3 receptor was purified by sucrose gradient centrifugation and column chromatography with heparin-agarose and wheat germ agglutinin-agarose. The receptor is an oligomer of a single polypeptide with a M r of 224,000 as determined by SDS/PAGE. Negative-staining electron microscopy reveals that the receptor is a large pinwheel-like structure having surface dimensions of ∼250 x 250 angstrom with fourfold symmetry. The IP 3 receptor from smooth muscle is similar to the ryanodine receptor with regard to its large size and fourfold symmetry, albeit distinct with regard to appearance, protomer size, and ligand binding

A bioluminescence resonance energy transfer 2 (BRET2) assay for monitoring seven transmembrane receptor and insulin receptor crosstalk

DEFF Research Database (Denmark)

Sanni, Samra Joke; Kulahin, Nikolaj; Jorgensen, Rasmus

2017-01-01

The angiotensin AT1 receptor is a seven transmembrane (7TM) receptor, which mediates the regulation of blood pressure. Activation of angiotensin AT1 receptor may lead to impaired insulin signaling indicating crosstalk between angiotensin AT1 receptor and insulin receptor signaling pathways....... To elucidate the molecular mechanisms behind this crosstalk, we applied the BRET2 technique to monitor the effect of angiotensin II on the interaction between Rluc8 tagged insulin receptor and GFP2 tagged insulin receptor substrates 1, 4, 5 (IRS1, IRS4, IRS5) and Src homology 2 domain-containing protein (Shc......). We demonstrate that angiotensin II reduces the interaction between insulin receptor and IRS1 and IRS4, respectively, while the interaction with Shc is unaffected, and this effect is dependent on Gαq activation. Activation of other Gαq-coupled 7TM receptors led to a similar reduction in insulin...

The repertoire of olfactory C family G protein-coupled receptors in zebrafish: candidate chemosensory receptors for amino acids

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Ngai John

2006-12-01

Full Text Available Abstract Background Vertebrate odorant receptors comprise at least three types of G protein-coupled receptors (GPCRs: the OR, V1R, and V2R/V2R-like receptors, the latter group belonging to the C family of GPCRs. These receptor families are thought to receive chemosensory information from a wide spectrum of odorant and pheromonal cues that influence critical animal behaviors such as feeding, reproduction and other social interactions. Results Using genome database mining and other informatics approaches, we identified and characterized the repertoire of 54 intact "V2R-like" olfactory C family GPCRs in the zebrafish. Phylogenetic analysis – which also included a set of 34 C family GPCRs from fugu – places the fish olfactory receptors in three major groups, which are related to but clearly distinct from other C family GPCRs, including the calcium sensing receptor, metabotropic glutamate receptors, GABA-B receptor, T1R taste receptors, and the major group of V2R vomeronasal receptor families. Interestingly, an analysis of sequence conservation and selective pressure in the zebrafish receptors revealed the retention of a conserved sequence motif previously shown to be required for ligand binding in other amino acid receptors. Conclusion Based on our findings, we propose that the repertoire of zebrafish olfactory C family GPCRs has evolved to allow the detection and discrimination of a spectrum of amino acid and/or amino acid-based compounds, which are potent olfactory cues in fish. Furthermore, as the major groups of fish receptors and mammalian V2R receptors appear to have diverged significantly from a common ancestral gene(s, these receptors likely mediate chemosensation of different classes of chemical structures by their respective organisms.

Intracellular insulin-receptor dissociation and segregation in a rat fibroblast cell line transfected with a human insulin receptor gene

International Nuclear Information System (INIS)

Levy, J.R.; Olefsky, J.M.

1988-01-01

The cellular processing of insulin and insulin receptors was studied using a rat fibroblast cell line that had been transfected with a normal human insulin receptor gene, expressing approximately 500 times the normal number of native fibroblasts insulin receptors. These cells bind and internalize insulin normally. Biochemically assays based on the selective precipitation by polyethylene glycol of intact insulin-receptor complexes but not of free intracellular insulin were developed to study the time course of intracellular insulin-receptor dissociation. Fibroblasts were incubated with radiolabeled insulin at 4 0 C, and internalization of insulin-receptor complexes was initiated by warming the cells to 37 0 C. Within 2 min, 90% of the internalized radioactivity was composed of intact insulin-receptor complexes. The dissociation of insulin from internalized insulin-receptor complexes was markedly inhibited by monensin and chloroquine. Furthermore, chloroquine markedly increased the number of cross-linkable intracellular insulin-receptor complexes, as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis autoradiography. These findings suggest that acidification of intracellular vesicles is responsible for insulin-receptor dissociation. Physical segregation of dissociated intracellular insulin from its receptor was monitored. The results are consistent with the view that segregation of insulin and receptor occurs 5-10 min after initiation of dissociation. These studies demonstrate the intracellular itinerary of insulin-receptor complexes, including internalization, dissociation of insulin from the internalized receptor within an acidified compartment, segregation of insulin from the receptor, and subsequent ligand degradation

Functional ET(A)-ET(B) Receptor Cross-talk in Basilar Artery In Situ From ET(B) Receptor Deficient Rats.

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Yoon, SeongHun; Gariepy, Cheryl E; Yanagisawa, Masashi; Zuccarello, Mario; Rapoport, Robert M

2016-03-01

The role of endothelin (ET)(A)-ET(B) receptor cross-talk in limiting the ET(A) receptor antagonist inhibition of ET-1 constriction is revealed by the partial or complete dependency of the ET(A) receptor antagonist inhibition on functional removal of the ET(B) receptor. Although functional removal of the ET(B) receptor is generally accomplished with ET(B) receptor antagonist, a novel approach using rats containing a naturally occurring deletion mutation in the ET(B) receptor [rescued "spotting lethal" (sl) rats; ET(B)(sl/sl)] demonstrated increased ET(A) receptor antagonist inhibition of ET-1 constriction in vena cava. We investigated whether this deletion mutation was also sufficient to remove the ET(B) receptor dependency of the ET(A) receptor antagonist inhibition of ET-1 constriction in the basilar artery. Consistent with previous reports, ET-1 plasma levels were elevated in ET(B)(sl/sl) as compared with ET(B)(+/+) rats. ET(B) receptor antagonist failed to relax the ET-1 constricted basilar artery from ET(B)(+/+) and ET(B)(sl/sl) rats. Relaxation to combined ET(A) and ET(B) receptor antagonist was greater than relaxation to ET(A) receptor antagonist in the basilar artery from ET(B)(+/+) and, unexpectedly, ET(B)(sl/sl) rats. These findings confirm the presence of ET(A)-ET(B) receptor cross-talk in the basilar artery. We speculate that mutant ET(B) receptor expression produced by alternative splicing may be sufficient to allow cross-talk.

Dual hypocretin receptor antagonism is more effective for sleep promotion than antagonism of either receptor alone.

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Stephen R Morairty

Full Text Available The hypocretin (orexin system is involved in sleep/wake regulation, and antagonists of both hypocretin receptor type 1 (HCRTR1 and/or HCRTR2 are considered to be potential hypnotic medications. It is currently unclear whether blockade of either or both receptors is more effective for promoting sleep with minimal side effects. Accordingly, we compared the properties of selective HCRTR1 (SB-408124 and SB-334867 and HCRTR2 (EMPA antagonists with that of the dual HCRTR1/R2 antagonist almorexant in the rat. All 4 antagonists bound to their respective receptors with high affinity and selectivity in vitro. Since in vivo pharmacokinetic experiments revealed poor brain penetration for SB-408124, SB-334867 was selected for subsequent in vivo studies. When injected in the mid-active phase, SB-334867 produced small increases in rapid-eye-movement (REM and non-REM (NR sleep. EMPA produced a significant increase in NR only at the highest dose studied. In contrast, almorexant decreased NR latency and increased both NR and REM proportionally throughout the subsequent 6 h without rebound wakefulness. The increased NR was due to a greater number of NR bouts; NR bout duration was unchanged. At the highest dose tested (100 mg/kg, almorexant fragmented sleep architecture by increasing the number of waking and REM bouts. No evidence of cataplexy was observed. HCRTR1 occupancy by almorexant declined 4-6 h post-administration while HCRTR2 occupancy was still elevated after 12 h, revealing a complex relationship between occupancy of HCRT receptors and sleep promotion. We conclude that dual HCRTR1/R2 blockade is more effective in promoting sleep than blockade of either HCRTR alone. In contrast to GABA receptor agonists which induce sleep by generalized inhibition, HCRTR antagonists seem to facilitate sleep by reducing waking "drive".

Or47b receptor neurons mediate sociosexual interactions in the fruit fly Drosophila melanogaster.

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Lone, Shahnaz Rahman; Sharma, Vijay Kumar

2012-04-01

In the fruit fly Drosophila melanogaster, social interactions especially among heterosexual couples have been shown to have significant impact on the circadian timing system. Olfaction plays a major role in such interactions; however, we do not know yet specifically which receptor(s) are involved. Further, the role of circadian clock neurons in the rhythmic regulation of such sociosexual interactions (SSIs) is not fully understood. Here, we report the results of our study in which we assayed the locomotor activity and sleep-wake behaviors of male-male (MM), female-female (FF), and male-female (MF) couples from several wild-type and mutant strains of Drosophila with an aim to identify specific olfactory receptor(s) and circadian clock neurons involved in the rhythmic regulation of SSI. The results indicate that Or47b receptor neurons are necessary for SSI, as ablation or silencing of these neurons has a severe impact on SSI. Further, the neuropeptide pigment dispersing factor (PDF) and PDF-positive ventral lateral (LN(v)) clock neurons appear to be dispensable for the regulation of SSI; however, dorsal neurons may be involved.

Subtype selective kainic acid receptor agonists

DEFF Research Database (Denmark)

Bunch, Lennart; Krogsgaard-Larsen, Povl

2009-01-01

(S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the mammalian central nervous system, activating the plethora of glutamate receptors (GluRs). In broad lines, the GluRs are divided into two major classes: the ionotropic Glu receptors (iGluRs) and the metabotropic Glu receptors (m......GluRs). Within the iGluRs, five subtypes (KA1, KA2, iGluR5-7) show high affinity and express full agonist activity upon binding of the naturally occurring amino acid kainic acid (KA). Thus these receptors have been named the KA receptors. This review describes all-to our knowledge-published KA receptor agonists...

The estrogen-related receptors and the adipocyte.

Science.gov (United States)

Carnesecchi, Julie; Vanacker, Jean-Marc

2013-08-01

The estrogen-related receptors (ERRα, β, and γ) are orphan members of the nuclear receptor superfamily. ERRα and γ are highly expressed in tissues displaying elevated energy demands and are involved in several aspects of energetic metabolism, which they regulate mostly in association with members of the PGC-1 coactivator family. These activities have mostly been documented in the liver, heart, or skeletal muscle. ERRα and γ are also highly expressed in adipocytes. Their precise roles in this cell type are less documented, although published data indicate that they contribute to cell differentiation as well as functionality. This review describes these activities.

Hypoxia increases pulmonary arterial thromboxane receptor internalization independent of receptor sensitization.

Science.gov (United States)

Fediuk, J; Sikarwar, A S; Lizotte, P P; Hinton, M; Nolette, N; Dakshinamurti, S

2015-02-01

Persistent Pulmonary Hypertension of the Newborn (PPHN) is characterized by sustained vasospasm and an increased thromboxane:prostacyclin ratio. Thromboxane (TP) receptors signal via Gαq to mobilize IP3 and Ca(2+), causing pulmonary arterial constriction. We have previously reported increased TP internalization in hypoxic pulmonary arterial (PA) myocytes. Serum-deprived PA myocytes were grown in normoxia (NM) or hypoxia (HM) for 72 h. TP localization was visualized in agonist-naïve and -challenged NM and HM by immunocytochemistry. Pathways for agonist-induced TP receptor internalization were determined by inhibiting caveolin- or clathrin-mediated endocytosis, and caveolar fractionation. Roles of actin and tubulin in TP receptor internalization were assessed using inhibitors of tubulin, actin-stabilizing or -destabilizing agents. PKA, PKC or GRK activation and inhibition were used to determine the kinase responsible for post-agonist receptor internalization. Agonist-naïve HM had decreased cell surface TP, and greater TP internalization after agonist challenge. TP protein did not sort with caveolin-rich fractions. Inhibition of clathrin prevented TP internalization. Both actin-stabilizing and -destabilizing agents prevented TP endocytosis in NM, while normalizing TP internalization in HM. Velocity of TP internalization was unaffected by PKA activity, but PKC activation normalized TP receptor internalization in HM. GRK inhibition had no effect. We conclude that in hypoxic myocytes, TP is internalized faster and to a greater extent than in normoxic controls. Internalization of the agonist-challenged TP requires clathrin, dynamic actin and is sensitive to PKC activity. TP receptor trafficking and signaling in hypoxia are pivotal to understanding increased vasoconstrictor sensitivity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Positron emission tomography studies of central receptors in humans

International Nuclear Information System (INIS)

Baron, J.C.; Maziere, B.

1986-01-01

Central neurotransmitter systems and receptors are intimately involved in the mechanism of several neurologic and psychiatric disorders. One well-known example is the nigro-striatal dopaminergic system in akinesia of Parkinson's disease. Although neurotransmitter concentration and receptor function can be measured regionally post-mortem, positron tomography (PET) studies can be performed during life and therefore may provide insight into changes at early stages of the disease as well as follow-up data on, and pharmacological modification of, such changes. PET allows to monitor non-invasively the time-course of regional tissue tracer concentration following administration of a radioactive drug. If the latter is known to interact selectively with specific binding sites, it can be used to probe in vivo the regional distribution and affinity of the receptors involved. This principle was first pioneered using 3 H or 14 C-labeled ligands injected intravenously to laboratory animal, but necessitated brain tissue sampling for determination of regional radioactive concentration. The feasibility of the PET paradigm to characterize specific binding in vivo showed that trace amounts of 11 C-labeled flunitrazepam could be displaced specifically from the baboon's brain by a therapeutic load of the unlabeled competitor Lorazepam, indicating that specific in vivo binding of the radioligand to the benzodiazepine (BZD) receptors has taken place

Toll-like receptor 2 or toll-like receptor 4 deficiency does not modify lupus in MRLlpr mice.

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Simon J Freeley

Full Text Available Systemic lupus erythematosus is an autoimmune disease with a high morbidity and nephritis is a common manifestation. Previous studies in murine lupus models have suggest a role for Toll-like receptor 2 and 4. We examined the role of these molecules in MRL lpr mice which is one of the most established and robust murine models. We compared disease parameters in Toll-like receptor 2 or Toll-like receptor 4 deficient mice with their littermate controls. We found no difference in the severity of glomerulonephritis as assessed by histology, serum creatinine and albuminuria when Toll-like receptor 2 or Toll-like receptor 4 deficient MRLlpr mice were compared with Toll-like receptor sufficient controls. We also found similar levels of anti-dsDNA and anti-ssDNA antibodies. These results show that Toll-like receptor 2 and Toll-like receptor 4 do not play a significant role in MRLlpr mice, and therefore they may not be important in human lupus.

β1-adrenergic receptor stimulation by agonist Compound 49b restores insulin receptor signal transduction in vivo

Science.gov (United States)

Jiang, Youde; Zhang, Qiuhua; Ye, Eun-Ah

2014-01-01

Purpose Determine whether Compound 49b treatment ameliorates retinal changes due to the lack of β2-adrenergic receptor signaling. Methods Using retinas from 3-month-old β2-adrenergic receptor-deficient mice, we treated mice with our novel β1-/β2-adrenergic receptor agonist, Compound 49b, to assess the effects of adrenergic agonists acting only on β1-adrenergic receptors due to the absence of β2-adrenergic receptors. Western blotting or enzyme-linked immunosorbent assay (ELISA) analyses were performed for β1- and β2-adrenergic receptors, as well as key insulin resistance proteins, including TNF-α, SOCS3, IRS-1Ser307, and IRTyr960. Analyses were also performed on key anti- and proapoptotic proteins: Akt, Bcl-xL, Bax, and caspase 3. Electroretinogram analyses were conducted to assess functional changes, while histological assessment was conducted for changes in retinal thickness. Results A 2-month treatment of β2-adrenergic receptor-deficient mice with daily eye drops of 1 mM Compound 49b, a novel β1- and β2-adrenergic receptor agonist, reversed the changes in insulin resistance markers (TNF-α and SOCS3) observed in untreated β2-adrenergic receptor-deficient mice, and concomitantly increased morphological integrity (retinal thickness) and functional responses (electroretinogram amplitude). These results suggest that stimulating β1-adrenergic receptors on retinal endothelial cells or Müller cells can compensate for the loss of β2-adrenergic receptor signaling on Müller cells, restore insulin signal transduction, reduce retinal apoptosis, and enhance retinal function. Conclusions Since our previous studies with β1-adrenergic receptor knockout mice confirmed that the reverse also occurs (β2-adrenergic receptor stimulation can compensate for the loss of β1-adrenergic receptor activity), it appears that increased activity in either of these pathways alone is sufficient to block insulin resistance–based retinal cell apoptosis. PMID:24966659

Protein Connectivity in Chemotaxis Receptor Complexes.

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Stephan Eismann

2015-12-01

Full Text Available The chemotaxis sensory system allows bacteria such as Escherichia coli to swim towards nutrients and away from repellents. The underlying pathway is remarkably sensitive in detecting chemical gradients over a wide range of ambient concentrations. Interactions among receptors, which are predominantly clustered at the cell poles, are crucial to this sensitivity. Although it has been suggested that the kinase CheA and the adapter protein CheW are integral for receptor connectivity, the exact coupling mechanism remains unclear. Here, we present a statistical-mechanics approach to model the receptor linkage mechanism itself, building on nanodisc and electron cryotomography experiments. Specifically, we investigate how the sensing behavior of mixed receptor clusters is affected by variations in the expression levels of CheA and CheW at a constant receptor density in the membrane. Our model compares favorably with dose-response curves from in vivo Förster resonance energy transfer (FRET measurements, demonstrating that the receptor-methylation level has only minor effects on receptor cooperativity. Importantly, our model provides an explanation for the non-intuitive conclusion that the receptor cooperativity decreases with increasing levels of CheA, a core signaling protein associated with the receptors, whereas the receptor cooperativity increases with increasing levels of CheW, a key adapter protein. Finally, we propose an evolutionary advantage as explanation for the recently suggested CheW-only linker structures.

Constitutive dimerization of the G-protein coupled receptor, neurotensin receptor 1, reconstituted into phospholipid bilayers.

Science.gov (United States)

Harding, Peter J; Attrill, Helen; Boehringer, Jonas; Ross, Simon; Wadhams, George H; Smith, Eleanor; Armitage, Judith P; Watts, Anthony

2009-02-01

Neurotensin receptor 1 (NTS1), a Family A G-protein coupled receptor (GPCR), was expressed in Escherichia coli as a fusion with the fluorescent proteins eCFP or eYFP. A fluorophore-tagged receptor was used to study the multimerization of NTS1 in detergent solution and in brain polar lipid bilayers, using fluorescence resonance energy transfer (FRET). A detergent-solubilized receptor was unable to form FRET-competent complexes at concentrations of up to 200 nM, suggesting that the receptor is monomeric in this environment. When reconstituted into a model membrane system at low receptor density, the observed FRET was independent of agonist binding, suggesting constitutive multimer formation. In competition studies, decreased FRET in the presence of untagged NTS1 excludes the possibility of fluorescent protein-induced interactions. A simulation of the experimental data indicates that NTS1 exists predominantly as a homodimer, rather than as higher-order multimers. These observations suggest that, in common with several other Family A GPCRs, NTS1 forms a constitutive dimer in lipid bilayers, stabilized through receptor-receptor interactions in the absence of other cellular signaling components. Therefore, this work demonstrates that well-characterized model membrane systems are useful tools for the study of GPCR multimerization, allowing fine control over system composition and complexity, provided that rigorous control experiments are performed.

Atypical nuclear localization of VIP receptors in glioma cell lines and patients

Energy Technology Data Exchange (ETDEWEB)

Barbarin, Alice; Séité, Paule [Equipe Récepteurs, Régulations et Cellules Tumorales, Université de Poitiers, PBS bât 36, 1 rue Georges Bonnet, TSA 51106, 86073 Poitiers Cedex 9 (France); Godet, Julie [Laboratoire d’anatomie et de cytologie pathologiques, CHU de Poitiers, 2 rue de la Milétrie, 86000 Poitiers (France); Bensalma, Souheyla; Muller, Jean-Marc [Equipe Récepteurs, Régulations et Cellules Tumorales, Université de Poitiers, PBS bât 36, 1 rue Georges Bonnet, TSA 51106, 86073 Poitiers Cedex 9 (France); Chadéneau, Corinne, E-mail: corinne.chadeneau@univ-poitiers.fr [Equipe Récepteurs, Régulations et Cellules Tumorales, Université de Poitiers, PBS bât 36, 1 rue Georges Bonnet, TSA 51106, 86073 Poitiers Cedex 9 (France)

2014-11-28

Highlights: • The VIP receptor VPAC1 contains a putative NLS signal. • VPAC1 is predominantly nuclear in GBM cell lines but not VPAC2. • Non-nuclear VPAC1/2 protein expression is correlated with glioma grade. • Nuclear VPAC1 is observed in 50% of stage IV glioma (GBM). - Abstract: An increasing number of G protein-coupled receptors, like receptors for vasoactive intestinal peptide (VIP), are found in cell nucleus. As VIP receptors are involved in the regulation of glioma cell proliferation and migration, we investigated the expression and the nuclear localization of the VIP receptors VPAC1 and VPAC2 in this cancer. First, by applying Western blot and immunofluorescence detection in three human glioblastoma (GBM) cell lines, we observed a strong nuclear staining for the VPAC1 receptor and a weak nuclear VPAC2 receptor staining. Second, immunohistochemical staining of VPAC1 and VPAC2 on tissue microarrays (TMA) showed that the two receptors were expressed in normal brain and glioma tissues. Expression in the non-nuclear compartment of the two receptors significantly increased with the grade of the tumors. Analysis of nuclear staining revealed a significant increase of VPAC1 staining with glioma grade, with up to 50% of GBM displaying strong VPAC1 nuclear staining, whereas nuclear VPAC2 staining remained marginal. The increase in VPAC receptor expression with glioma grades and the enhanced nuclear localization of the VPAC1 receptors in GBM might be of importance for glioma progression.

P2Y12 receptor upregulation in satellite glial cells is involved in neuropathic pain induced by HIV glycoprotein 120 and 2',3'-dideoxycytidine.

Science.gov (United States)

Yi, Zhihua; Xie, Lihui; Zhou, Congfa; Yuan, Huilong; Ouyang, Shuai; Fang, Zhi; Zhao, Shanhong; Jia, Tianyu; Zou, Lifang; Wang, Shouyu; Xue, Yun; Wu, Bing; Gao, Yun; Li, Guilin; Liu, Shuangmei; Xu, Hong; Xu, Changshui; Zhang, Chunping; Liang, Shangdong

2018-03-01

The direct neurotoxicity of HIV and neurotoxicity of combination antiretroviral therapy medications both contribute to the development of neuropathic pain. Activation of satellite glial cells (SGCs) in the dorsal root ganglia (DRG) plays a crucial role in mechanical and thermal hyperalgesia. The P2Y 12 receptor expressed in SGCs of the DRG is involved in pain transmission. In this study, we explored the role of the P2Y 12 receptor in neuropathic pain induced by HIV envelope glycoprotein 120 (gp120) combined with ddC (2',3'-dideoxycytidine). A rat model of gp120+ddC-induced neuropathic pain was used. Peripheral nerve exposure to HIV-gp120+ddC increased mechanical and thermal hyperalgesia in gp120+ddC-treated model rats. The gp120+ddC treatment increased expression of P2Y 12 receptor mRNA and protein in DRG SGCs. In primary cultured DRG SGCs treated with gp120+ddC, the levels of [Ca 2+ ] i activated by the P2Y 12 receptor agonist 2-(Methylthio) adenosine 5'-diphosphate trisodium salt (2-MeSADP) were significantly increased. P2Y 12 receptor shRNA treatment inhibited 2-MeSADP-induced [Ca 2+ ] i in primary cultured DRG SGCs treated with gp120+ddC. Intrathecal treatment with a shRNA against P2Y 12 receptor in DRG SGCs reduced the release of pro-inflammatory cytokines, decreased phosphorylation of p38 MAPK in the DRG of gp120+ddC-treated rats. Thus, downregulating the P2Y 12 receptor relieved mechanical and thermal hyperalgesia in gp120+ddC-treated rats.

Crystal structure of NL63 respiratory coronavirus receptor-binding domain complexed with its human receptor

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Wu, Kailang; Li, Weikai; Peng, Guiqing; Li, Fang; (Harvard-Med); (UMM-MED)

2010-03-04

NL63 coronavirus (NL63-CoV), a prevalent human respiratory virus, is the only group I coronavirus known to use angiotensin-converting enzyme 2 (ACE2) as its receptor. Incidentally, ACE2 is also used by group II SARS coronavirus (SARS-CoV). We investigated how different groups of coronaviruses recognize the same receptor, whereas homologous group I coronaviruses recognize different receptors. We determined the crystal structure of NL63-CoV spike protein receptor-binding domain (RBD) complexed with human ACE2. NL63-CoV RBD has a novel {beta}-sandwich core structure consisting of 2 layers of {beta}-sheets, presenting 3 discontinuous receptor-binding motifs (RBMs) to bind ACE2. NL63-CoV and SARS-CoV have no structural homology in RBD cores or RBMs; yet the 2 viruses recognize common ACE2 regions, largely because of a 'virus-binding hotspot' on ACE2. Among group I coronaviruses, RBD cores are conserved but RBMs are variable, explaining how these viruses recognize different receptors. These results provide a structural basis for understanding viral evolution and virus-receptor interactions.

NMDA and AMPA/kainate glutamatergic receptors in the prelimbic medial prefrontal cortex modulate the elaborated defensive behavior and innate fear-induced antinociception elicited by GABAA receptor blockade in the medial hypothalamus.

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de Freitas, Renato Leonardo; Salgado-Rohner, Carlos José; Biagioni, Audrey Francisco; Medeiros, Priscila; Hallak, Jaime Eduardo Cecílio; Crippa, José Alexandre S; Coimbra, Norberto Cysne

2014-06-01

The aim of the present study was to investigate the involvement of N-methyl-d-aspartate (NMDA) and amino-3-hydroxy-5-methyl-isoxazole-4-proprionate (AMPA)/kainate receptors of the prelimbic (PL) division of the medial prefrontal cortex (MPFC) on the panic attack-like reactions evoked by γ-aminobutyric acid-A receptor blockade in the medial hypothalamus (MH). Rats were pretreated with NaCl 0.9%, LY235959 (NMDA receptor antagonist), and NBQX (AMPA/kainate receptor antagonist) in the PL at 3 different concentrations. Ten minutes later, the MH was treated with bicuculline, and the defensive responses were recorded for 10 min. The antagonism of NMDA receptors in the PL decreased the frequency and duration of all defensive behaviors evoked by the stimulation of the MH and reduced the innate fear-induced antinociception. However, the pretreatment of the PL cortex with NBQX was able to decrease only part of defensive responses and innate fear-induced antinociception. The present findings suggest that the NMDA-glutamatergic system of the PL is critically involved in panic-like responses and innate fear-induced antinociception and those AMPA/kainate receptors are also recruited during the elaboration of fear-induced antinociception and in panic attack-related response. The activation of the glutamatergic neurotransmission of PL division of the MPFC during the elaboration of oriented behavioral reactions elicited by the chemical stimulation of the MH recruits mainly NMDA receptors in comparison with AMPA/kainate receptors.

Fibroblast growth factor receptors in breast cancer.

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Wang, Shuwei; Ding, Zhongyang

2017-05-01

Fibroblast growth factor receptors are growth factor receptor tyrosine kinases, exerting their roles in embryogenesis, tissue homeostasis, and development of breast cancer. Recent genetic studies have identified some subtypes of fibroblast growth factor receptors as strong genetic loci associated with breast cancer. In this article, we review the recent epidemiological findings and experiment results of fibroblast growth factor receptors in breast cancer. First, we summarized the structure and physiological function of fibroblast growth factor receptors in humans. Then, we discussed the common genetic variations in fibroblast growth factor receptors that affect breast cancer risk. In addition, we also introduced the potential roles of each fibroblast growth factor receptors isoform in breast cancer. Finally, we explored the potential therapeutics targeting fibroblast growth factor receptors for breast cancer. Based on the biological mechanisms of fibroblast growth factor receptors leading to the pathogenesis in breast cancer, targeting fibroblast growth factor receptors may provide new opportunities for breast cancer therapeutic strategies.

Involvement of aberrant DNA methylation on reduced expression of lysophosphatidic acid receptor-1 gene in rat tumor cell lines

International Nuclear Information System (INIS)

Tsujiuchi, Toshifumi; Shimizu, Kyoko; Onishi, Mariko; Sugata, Eriko; Fujii, Hiromasa; Mori, Toshio; Honoki, Kanya; Fukushima, Nobuyuki

2006-01-01

Lysophosphatidic acid (LPA) is a bioactive phospholipid that stimulates cell proliferation, migration, and protects cells from apoptosis. It interacts with specific G protein-coupled transmembrane receptors. Recently, it has been reported that alterations of LPA receptor expression might be important in the malignant transformation of tumor cells. Therefore, to assess an involvement of DNA methylation in reduced expression of the LPA receptor-1 (lpa1) gene, we investigated the expression of the lpa1 gene and its DNA methylation patterns in rat tumor cell lines. Both rat brain-derived neuroblastoma B103 and liver-derived hepatoma RH7777 cells used in this study indicated no expression of lpa1. For the analysis of methylation status, bisulfite sequencing was performed with B103 and RH7777 cells, comparing with other lpa1 expressed cells and normal tissues of brain and liver. The lpa1 expressed cells and tissues were all unmethylated in this region of lpa1. In contrast, both B103 and RH7777 cells were highly methylated, correlating with reduced expression of the lpa1. Treatment with 5-aza 2'-deoxycytidine induced expression of lpa1 gene in B103 and RH7777 cells after 24 h. In RH7777 cells treated with 5-aza 2'-deoxycytidine, stress fiber formation was also observed in response to LPA in RH7777 cells, but not in untreated RH7777 cells. These results suggest that aberrant DNA methylation of the lpa1 gene may be involved in its reduced expression in rat tumor cells

The Role of Estrogen Receptor β in Prostate Cancer

OpenAIRE

Christoforou, Paraskevi; Christopoulos, Panagiotis F; Koutsilieris, Michael

2014-01-01

Although androgen receptor (AR) signaling is the main molecular tool regulating growth and function of the prostate gland, estrogen receptor β (ERβ) is involved in the differentiation of prostatic epithelial cells and numerous antiproliferative actions on prostate cancer cells. However, ERβ splice variants have been associated with prostate cancer initiation and progression mechanisms. ERβ is promising as an anticancer therapy and in the prevention of prostate cancer. Herein, we review the re...

Sigma opioid receptor: characterization and co-identity with the phencyclidine receptor

International Nuclear Information System (INIS)

Mendelsohn, L.G.; Kalra, V.; Johnson, B.G.; Kerchner, G.A.

1985-01-01

The properties of the sigma opioid receptor of rat brain cortex have been characterized using the prototypic ligand (+)-[ 3 H] SKF 10,047. Binding to this receptor was rapid, and equilibrium was obtained within 30 min at 37 degrees C. Specific binding was linear with protein concentration up to 500 micrograms/2 ml and was dependent upon protein integrity. Denaturation by boiling destroyed over 95% of the specific binding. A high-affinity binding site with a KD of 150 +/- 40 nM and a maximum binding of 2.91 +/- 0.84 pmol/mg of protein was determined from a Scatchard plot of the binding data. The addition of salt, either NaCl or CaCl 2 , to the buffers markedly decreased binding, with CaCl 2 being more potent than NaCl. A broad pH optimum for specific binding was observed; maximum binding was at pH 9.0. The affinity of a number of ligands for the sigma site and the phencyclidine receptor were compared. The binding (IC50) of 13 ligands to the sigma site showed a correlation of 0.86 (P less than .01) with binding to the phencyclidine site. The data demonstrate that the biochemical properties of the sigma and phencyclidine receptors are similar and support the view that these receptors are one and the same site

Downstream of tyrosine kinase/docking protein 6, as a novel substrate of tropomyosin-related kinase C receptor, is involved in neurotrophin 3-mediated neurite outgrowth in mouse cortex neurons

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Yuan Jian

2010-06-01

Full Text Available Abstract Background The downstream of tyrosine kinase/docking protein (Dok adaptor protein family has seven members, Dok1 to Dok7, that act as substrates of multiple receptor tyrosine kinase and non-receptor tyrosine kinase. The tropomyosin-related kinase (Trk receptor family, which has three members (TrkA, TrkB and TrkC, are receptor tyrosine kinases that play pivotal roles in many stages of nervous system development, such as differentiation, migration, axon and dendrite projection and neuron patterning. Upon related neurotrophin growth factor stimulation, dimerisation and autophosphorylation of Trk receptors can occur, recruiting adaptor proteins to mediate signal transduction. Results In this report, by using yeast two-hybrid assays, glutathione S-transferase (GST precipitation assays and coimmunoprecipitation (Co-IP experiments, we demonstrate that Dok6 selectively binds to the NPQY motif of TrkC through its phosphotyrosine-binding (PTB domain in a kinase activity-dependent manner. We further confirmed their interaction by coimmunoprecipitation and colocalisation in E18.5 mouse cortex neurons, which provided more in vivo evidence. Next, we demonstrated that Dok6 is involved in neurite outgrowth in mouse cortex neurons via the RNAi method. Knockdown of Dok6 decreased neurite outgrowth in cortical neurons upon neurotrophin 3 (NT-3 stimulation. Conclusions We conclude that Dok6 interacts with the NPQY motif of the TrkC receptor through its PTB domain in a kinase activity-dependent manner, and works as a novel substrate of the TrkC receptor involved in NT-3-mediated neurite outgrowth in mouse cortex neurons.

Insulin Receptor Substrate 2 Is a Negative Regulator of Memory Formation

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Irvine, Elaine E.; Drinkwater, Laura; Radwanska, Kasia; Al-Qassab, Hind; Smith, Mark A.; O'Brien, Melissa; Kielar, Catherine; Choudhury, Agharul I.; Krauss, Stefan; Cooper, Jonathan D.; Withers, Dominic J.; Giese, Karl Peter

2011-01-01

Insulin has been shown to impact on learning and memory in both humans and animals, but the downstream signaling mechanisms involved are poorly characterized. Insulin receptor substrate-2 (Irs2) is an adaptor protein that couples activation of insulin- and insulin-like growth factor-1 receptors to downstream signaling pathways. Here, we have…

Odor memories regulate olfactory receptor expression in the sensory periphery.

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Claudianos, Charles; Lim, Julianne; Young, Melanie; Yan, Shanzhi; Cristino, Alexandre S; Newcomb, Richard D; Gunasekaran, Nivetha; Reinhard, Judith

2014-05-01

Odor learning induces structural and functional modifications throughout the olfactory system, but it is currently unknown whether this plasticity extends to the olfactory receptors (Or) in the sensory periphery. Here, we demonstrate that odor learning induces plasticity in olfactory receptor expression in the honeybee, Apis mellifera. Using quantitative RT-PCR analysis, we show that six putative floral scent receptors were differentially expressed in the bee antennae depending on the scent environment that the bees experienced. Or151, which we characterized using an in vitro cell expression system as a broadly tuned receptor binding floral odorants such as linalool, and Or11, the specific receptor for the queen pheromone 9-oxo-decenoic acid, were significantly down-regulated after honeybees were conditioned with the respective odorants in an olfactory learning paradigm. Electroantennogram recordings showed that the neural response of the antenna was similarly reduced after odor learning. Long-term odor memory was essential for inducing these changes, suggesting that the molecular mechanisms involved in olfactory memory also regulate olfactory receptor expression. Our study demonstrates for the first time that olfactory receptor expression is experience-dependent and modulated by scent conditioning, providing novel insight into how molecular regulation at the periphery contributes to plasticity in the olfactory system. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Role of ethylene receptors during senescence and ripening in horticultural crops

Science.gov (United States)

Agarwal, Gaurav; Choudhary, Divya; Singh, Virendra P.; Arora, Ajay

2012-01-01

The past two decades have been rewarding in terms of deciphering the ethylene signal transduction and functional validation of the ethylene receptor and downstream genes involved in the cascade. Our knowledge of ethylene receptors and its signal transduction pathway provides us a robust platform where we can think of manipulating and regulating ethylene sensitivity by the use of genetic engineering and making transgenic. This review focuses on ethylene perception, receptor mediated regulation of ethylene biosynthesis, role of ethylene receptors in flower senescence, fruit ripening and other effects induced by ethylene. The expression behavior of the receptor and downstream molecules in climacteric and non climacteric crops is also elaborated upon. Possible strategies and recent advances in altering the ethylene sensitivity of plants using ethylene receptor genes in an attempt to modulate the regulation and sensitivity to ethylene have also been discussed. Not only will these transgenic plants be a boon to post-harvest physiology and crop improvement but, it will also help us in discovering the mechanism of regulation of ethylene sensitivity. PMID:22751331

G-Protein Coupled Receptors: Surface Display and Biosensor Technology