Effects of a short-term reduction in brain serotonin synthesis on the availability of the soluble leptin receptor in healthy women.

PubMed

Zepf, F D; Dingerkus, V L S; Helmbold, K; Bubenzer-Busch, S; Biskup, C S; Herpertz-Dahlmann, B; Schaab, M; Kratzsch, J; Eisert, A; Rink, L; Hagenah, U; Gaber, T J

2015-03-01

Serotonin (5-HT) and the hormone leptin have been linked to the underlying neurobiology of appetite regulation with evidence coming from animal and cellular research, but direct evidence linking these two pathways in humans is lacking. We examined the effects of reduced brain 5-HT synthesis due to acute tryptophan depletion (ATD) on levels of soluble leptin receptor (sOb-R), the main high-affinity leptin binding protein, in healthy adults using an exploratory approach. Women, but not men, showed reduced sOb-R concentrations after ATD administration. With females showing reduced baseline levels of central 5-HT synthesis compared to males diminished brain 5-HT synthesis affected the leptin axis through the sOb-R in females, thereby potentially influencing their vulnerability to dysfunctional appetite regulation and co-morbid mood symptoms.

O-linked oligosaccharides on insulin receptor

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

Collier, E.; Gorden, P.

1991-02-01

The insulin receptor, an integral membrane glycoprotein, is synthesized as a single-chain precursor that is cleaved to produce two mature subunits, both of which contain N-linked oligosaccharide chains and covalently linked fatty acids. We report that the beta-subunit also contains O-linked oligosaccharides. The proreceptor, alpha-subunit, and beta-subunit were labeled with (3H)mannose and (3H)galactose in the presence or absence of an inhibitor of O-linked glycosylation. Tryptic peptides from each component were separated by reverse-phase high-performance liquid chromatography. N- and O-linked oligosaccharide chains were identified on these peptides by specific enzymatic digestions. The proreceptor and alpha-subunit contained only N-linked oligosaccharides, whereas themore » beta-subunit contained both N- and O-linked oligosaccharides. The O-linked oligosaccharide chains were attached to a single tryptic fraction of the beta-subunit, which also contained N-linked chains. This fraction was further localized to the NH2-terminal tryptic peptide of the beta-subunit by specific immunoprecipitation with an anti-peptide antibody with specificity for this region. Binding of insulin and autophosphorylation of the beta-subunit were not dependent on O-linked glycosylation, because cells grown in the presence of the inhibitor exhibited a normal dose response to insulin. Therefore, the insulin receptor contains O-linked oligosaccharides on the NH2-terminal tryptic peptide of the beta-subunit, and these O-linked oligosaccharides are not necessary to the binding or autophosphorylation function of the receptor.« less

Adenosine A2A receptors and depression.

PubMed

El Yacoubi, Malika; Costentin, Jean; Vaugeois, Jean-Marie

2003-12-09

Adenosine and its analogues have been shown to induce "behavioral despair" in animal models believed to be relevant to depression. Recent data have shown that selective adenosine A2A receptor antagonists (e.g., SCH 58261, ZM241385, and KW6002) or genetic inactivation of the receptor was effective in reversing signs of behavioral despair in the tail suspension and forced swim tests, two screening procedures predictive of antidepressant activity. A2A antagonists were active in the tail suspension test using either mice previously screened for having high immobility scores or mice that were selectively bred for their spontaneous "helplessness" in this test. At stimulant doses, caffeine, a nonselective A1/A2A receptor antagonist, was effective in the forced swim test. The authors have hypothesized that the antidepressant-like effect of selective A2A antagonists is linked to an interaction with dopaminergic transmission, possibly in the frontal cortex. In support of this idea, administration of the dopamine D2 receptor antagonist haloperidol prevented antidepressant-like effects elicited by SCH 58261 in the forced swim test (putatively involving cortex), whereas it had no effect on stimulant motor effects of SCH 58261 (putatively linked to ventral striatum). The interaction profile of caffeine with haloperidol differed markedly from that of SCH 58261 in the forced swim and motor activity tests. Therefore, a clear-cut antidepressant-like effect could not be ascribed to caffeine. In conclusion, available data support the proposition that a selective blockade of the adenosine A2A receptor may be an interesting target for the development of effective antidepressant agents.

Identification of the bombesin receptor on murine and human cells by cross-linking experiments.

PubMed

Kris, R M; Hazan, R; Villines, J; Moody, T W; Schlessinger, J

1987-08-15

The bombesin receptor present on the surface of murine and human cells was identified using 125I-labeled gastrin-releasing peptide as a probe, the cross-linking agent disuccinimidyl suberate, and sodium dodecyl sulfate gels. A clone of NIH-3T3 cells which possesses approximately 80,000 bombesin receptors/cell with a single binding constant of approximately 1.9 X 10(-9) M was used in these studies. In addition, we used Swiss 3T3 cells and a human glioma cell line which possesses approximately 100,000 and approximately 55,000 bombesin receptors/cell, respectively. Under conditions found optimal for binding, it is demonstrated that 125I-labeled gastrin-releasing peptide can be cross-linked specifically to a glycoprotein of apparent molecular mass of 65,000 daltons on the surface of the NIH-3T3 cells. Similar results were obtained when the cross-linked product was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing or non-reducing conditions. Moreover, the cross-linking reaction is specific and saturable and the 65,000-dalton polypeptide is not observed when the cross-linking experiments were performed with a NIH-3T3 cell line which is devoid of bombesin receptors. Interestingly, glycoproteins with apparent molecular weights of 75,000 were labeled specifically by 125I-labeled gastrin-releasing peptide when similar experiments were performed with Swiss 3T3 cells and with human glioma cell line GM-340. These different molecular weights may indicate differential glycosylation as treatment with the enzyme N-glycanase reduced the apparent molecular weight of the cross-linked polypeptide to 45,000. On the basis of these results it is concluded that the cross-linked polypeptides represent the bombesin receptor or the ligand-binding subunit of a putative larger bombesin receptor expressed on the surface of these cells.

THE CONCISE GUIDE TO PHARMACOLOGY 2017/18: Overview.

PubMed

Alexander, Stephen Ph; Kelly, Eamonn; Marrion, Neil V; Peters, John A; Faccenda, Elena; Harding, Simon D; Pawson, Adam J; Sharman, Joanna L; Southan, Christopher; Buneman, O Peter; Cidlowski, John A; Christopoulos, Arthur; Davenport, Anthony P; Fabbro, Doriano; Spedding, Michael; Striessnig, Jörg; Davies, Jamie A

2017-12-01

The Concise Guide to PHARMACOLOGY 2017/18 is the third in this series of biennial publications. This version provides concise overviews of the key properties of nearly 1800 human drug targets with an emphasis on selective pharmacology (where available), plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide represents approximately 400 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.13882/full. In addition to this overview, in which are identified 'Other protein targets' which fall outside of the subsequent categorisation, there are eight areas of focus: G protein-coupled receptors, ligand-gated ion channels, voltage-gated ion channels, other ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2017, and supersedes data presented in the 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature Committee of the Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate. © 2017 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.

Characterization of atrial natriuretic peptide receptors in brain microvessel endothelial cells

NASA Technical Reports Server (NTRS)

Whitson, P. A.; Huls, M. H.; Sams, C. F.

1991-01-01

Atrial natriuretic peptide (ANP) binding and ANP-induced increases in cyclic guanosine monophosphate (cGMP) levels have been observed in brain microvessels (Chabrier et al., 1987; Steardo and Nathanson, 1987), suggesting that this fluid-regulating hormone may play a role in the fluid homeostasis of the brain. This study was initiated to characterize the ANP receptors in primary cultures of brain microvessel endothelial cells (BMECs). The apparent equilibrium dissociation constant, Kd, for ANP increased from 0.25 nM to 2.5 nM, and the number of ANP binding sites as determined by Scatchard analysis increased from 7,100 to 170,000 sites/cell between 2 and 10 days of culture following monolayer formation. Time- and concentration-dependent studies on the stimulation of cGMP levels by ANP indicated that guanylate cyclase-linked ANP receptors were present in BMECs. The relative abilities of ANP, brain natriuretic peptide (BNP), and a truncated analog of ANP containing amino acids 5-27 (ANP 5-27) to modulate the accumulation of cGMP was found to be ANP greater than BNP much greater than ANP 5-27. Affinity cross-linking with disuccinimidyl suberate and radiolabeled ANP followed by gel electrophoresis under reducing conditions demonstrated a single band corresponding to the 60-70 kD receptor, indicating the presence of the nonguanylate cyclase-linked ANP receptor. Radiolabeled ANP binding was examined in the presence of various concentrations of either ANP, BNP, or ANP 5-27 and suggested that a large proportion of the ANP receptors present in blood-brain barrier endothelial cells bind all of these ligands similarly. These data indicate both guanylate cyclase linked and nonguanylate cyclase linked receptors are present on BMECs and that a higher proportion of the nonguanylate cyclase linked receptors is expressed. This in vitro culture system may provide a valuable tool for the examination of ANP receptor expression and function in blood-brain barrier endothelial cells.

Structure and Receptor Binding of the Hemagglutinin from a Human H6N1 Influenza Virus

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

Tzarum, Netanel; de Vries, Robert P.; Zhu, Xueyong

Avian influenza viruses that cause infection and are transmissible in humans involve changes in the receptor binding site (RBS) of the viral hemagglutinin (HA) that alter receptor preference from α2-3-linked (avian-like) to α2-6-linked (human-like) sialosides. A human case of avian-origin H6N1 influenza virus was recently reported, but the molecular mechanisms contributing to it crossing the species barrier are unknown. We find that, although the H6 HA RBS contains D190V and G228S substitutions that potentially promote human receptor binding, recombinant H6 HA preferentially binds α2-3-linked sialosides, indicating no adaptation to human receptors. Crystal structures of H6 HA with avian and humanmore » receptor analogs reveal that H6 HA preferentially interacts with avian receptor analogs. Lastly, this binding mechanism differs from other HA subtypes due to a unique combination of RBS residues, highlighting additional variation in HA-receptor interactions and the challenges in predicting which influenza strains and subtypes can infect humans and cause pandemics.« less

Structure and Receptor Binding of the Hemagglutinin from a Human H6N1 Influenza Virus

DOE PAGES

Tzarum, Netanel; de Vries, Robert P.; Zhu, Xueyong; ...

2015-03-11

Avian influenza viruses that cause infection and are transmissible in humans involve changes in the receptor binding site (RBS) of the viral hemagglutinin (HA) that alter receptor preference from α2-3-linked (avian-like) to α2-6-linked (human-like) sialosides. A human case of avian-origin H6N1 influenza virus was recently reported, but the molecular mechanisms contributing to it crossing the species barrier are unknown. We find that, although the H6 HA RBS contains D190V and G228S substitutions that potentially promote human receptor binding, recombinant H6 HA preferentially binds α2-3-linked sialosides, indicating no adaptation to human receptors. Crystal structures of H6 HA with avian and humanmore » receptor analogs reveal that H6 HA preferentially interacts with avian receptor analogs. Lastly, this binding mechanism differs from other HA subtypes due to a unique combination of RBS residues, highlighting additional variation in HA-receptor interactions and the challenges in predicting which influenza strains and subtypes can infect humans and cause pandemics.« less

In the Blink of an Eye: Relating Positive-Feedback Sensitivity to Striatal Dopamine D2-Like Receptors through Blink Rate

PubMed Central

Groman, Stephanie M.; James, Alex S.; Seu, Emanuele; Tran, Steven; Clark, Taylor A.; Harpster, Sandra N.; Crawford, Maverick; Burtner, Joanna Lee; Feiler, Karen; Roth, Robert H.; Elsworth, John D.; London, Edythe D.

2014-01-01

For >30 years, positron emission tomography (PET) has proven to be a powerful approach for measuring aspects of dopaminergic transmission in the living human brain; this technique has revealed important relationships between dopamine D2-like receptors and dimensions of normal behavior, such as human impulsivity, and psychopathology, particularly behavioral addictions. Nevertheless, PET is an indirect estimate that lacks cellular and functional resolution and, in some cases, is not entirely pharmacologically specific. To identify the relationships between PET estimates of D2-like receptor availability and direct in vitro measures of receptor number, affinity, and function, we conducted neuroimaging and behavioral and molecular pharmacological assessments in a group of adult male vervet monkeys. Data gathered from these studies indicate that variation in D2-like receptor PET measurements is related to reversal-learning performance and sensitivity to positive feedback and is associated with in vitro estimates of the density of functional dopamine D2-like receptors. Furthermore, we report that a simple behavioral measure, eyeblink rate, reveals novel and crucial links between neuroimaging assessments and in vitro measures of dopamine D2 receptors. PMID:25339755

Genetically encoded photocross-linkers determine the biological binding site of exendin-4 peptide in the N-terminal domain of the intact human glucagon-like peptide-1 receptor (GLP-1R)

PubMed Central

Koole, Cassandra; Reynolds, Christopher A.; Mobarec, Juan C.; Hick, Caroline; Sexton, Patrick M.; Sakmar, Thomas P.

2017-01-01

The glucagon-like peptide-1 receptor (GLP-1R) is a key therapeutic target in the management of type II diabetes mellitus, with actions including regulation of insulin biosynthesis and secretion, promotion of satiety, and preservation of β-cell mass. Like most class B G protein-coupled receptors (GPCRs), there is limited knowledge linking biological activity of the GLP-1R with the molecular structure of an intact, full-length, and functional receptor·ligand complex. In this study, we have utilized genetic code expansion to site-specifically incorporate the photoactive amino acid p-azido-l-phenylalanine (azF) into N-terminal residues of a full-length functional human GLP-1R in mammalian cells. UV-mediated photolysis of azF was then carried out to induce targeted photocross-linking to determine the proximity of the azido group in the mutant receptor with the peptide exendin-4. Cross-linking data were compared directly with the crystal structure of the isolated N-terminal extracellular domain of the GLP-1R in complex with exendin(9–39), revealing both similarities as well as distinct differences in the mode of interaction. Generation of a molecular model to accommodate the photocross-linking constraints highlights the potential influence of environmental conditions on the conformation of the receptor·peptide complex, including folding dynamics of the peptide and formation of dimeric and higher order oligomeric receptor multimers. These data demonstrate that crystal structures of isolated receptor regions may not give a complete reflection of peptide/receptor interactions and should be combined with additional experimental constraints to reveal peptide/receptor interactions occurring in the dynamic, native, and full-length receptor state. PMID:28283573

Characterization of the Igf-II Binding Site of the IGF-II/MAN-6-P Receptor Extracellular Domain.

NASA Astrophysics Data System (ADS)

Garmroudi, Farideh

1995-01-01

In mammals, insulin-like growth factor II (IGF -II) and glycoproteins bearing the mannose 6-phosphate (Man -6-P) recognition marker bind with high affinity to the same receptor. The functional consequences of IGF-II binding to the receptor at the cell surface are not clear. In these studies, we sought to broaden our understanding of the functional regions of the receptor regarding its IGF -II binding site. The IGF-II binding/cross-linking domain of the IGF-II/Man-6-P receptor was mapped by sequencing receptor fragments covalently attached to IGF-II. Purified rat placental or bovine liver receptors were affinity-labeled, with ^{125}I-IGF-II and digested with endoproteinase Glu-C. Analysis of digests by gel electrophoresis revealed a major radiolabeled band of 18 kDa, which was purified by gel filtration chromatography followed by reverse-phase HPLC and electroblotting. Sequence analysis revealed that, the peptide S(H)VNSXPMF, located within extracellular repeat 10 and beginning with serine 1488 of the bovine receptor, was the best candidate for the IGF-II cross-linked peptide. These data indicated that residues within repeats 10-11 were important for IGF -II binding. To define the location of the IGF-II binding site further, a nested set of six human receptor cDNA constructs was designed to produce epitope-tagged fusion proteins encompassing the region between repeats 8 and 11 of the human IGF-II/Man-6-P receptor extracellular domain. These truncated receptors were transiently expressed in COS-7 cells, immunoprecipitated and analyzed for their abilities to bind and cross-link to IGF-II. All of the constructs were capable of binding/cross-linking to IGF-II, except for the 9.0-11 construct. Displacement curve analysis indicated that the truncated receptors were approximately equivalent in IGF-II binding affinity, but were of 5- to 10-fold lower affinity than full-length receptors. Sequencing of the 9.0-11 construct indicated the presence of a point mutation substituting threonine for isoleucine at position 1621, which is located in the N-terminal half of repeat 11, and was found to abrogate IGF-II binding. Collectively, our work indicates that repeat 11 of the IGF-II/Man-6-P receptor's extracellular domain encompasses the elements both for binding and cross-linking to IGF-II.

Central peptidergic mechanisms controlling reproductive hormone secretion: novel methodology reveals a role for the natriuretic peptides.

PubMed

Samson, W K; Alexander, B D; Skala, K D; Huang, F L; Fulton, R J

1992-05-01

A variety of neural factors can influence reproductive hormone secretion by neuromodulatory actions within the hypothalamus or neuroendocrine actions within the anterior pituitary gland. Passive immunoneutralization and antagonist administration protocols have suggested physiological roles for a number of these factors; however, both experimental approaches have severe technical limitations. We have developed novel methodology utilizing cytotoxin cell targeting with neuropeptides linked to the toxic A chain of the plant cytotoxin ricin. With this methodology we can target and destroy in vivo or in vitro cells bearing receptors for that peptide. Ricin A chain conjugated to atrial natriuretic peptide (ANP), a neuropeptide known to pharmacologically inhibit luteinizing hormone-releasing hormone (LHRH) release, was injected into the cerebroventricular system of intact, cycling rats and ovariectomized rats. Cytotoxin conjugate treatment significantly lengthened the estrous cycle. In ovariectomized rats the luteinizing hormone surge induced by steroid priming was completely inhibited. LHRH content of the median eminences of these rats was not significantly altered. These data suggest that ANP binding to clearance receptors in the hypothalamus displaces the C-type natriuretic peptide (CNP) from the shared clearance receptor, making more CNP available to inhibit LHRH release. In the absence of cells bearing the clearance receptor all available CNP binds to the ANPR-B receptor and exerts its effect via an inhibitory interneuron, since LHRH fibers are spared by this treatment.

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

PubMed

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.

IRS2 mutations linked to invasion in pleomorphic invasive lobular carcinoma

PubMed Central

Zhu, Sha; Ward, B. Marie; Yu, Jun; Matthew-Onabanjo, Asia N.; Janusis, Jenny; Hsieh, Chung-Cheng; Tomaszewicz, Keith; Hutchinson, Lloyd; Zhu, Lihua Julie; Kandil, Dina; Shaw, Leslie M.

2018-01-01

Pleomorphic invasive lobular carcinoma (PILC) is an aggressive variant of invasive lobular breast cancer that is associated with poor clinical outcomes. Limited molecular data are available to explain the mechanistic basis for PILC behavior. To address this issue, targeted sequencing was performed to identify molecular alterations that define PILC. This sequencing analysis identified genes that distinguish PILC from classic ILC and invasive ductal carcinoma by the incidence of their genomic changes. In particular, insulin receptor substrate 2 (IRS2) is recurrently mutated in PILC, and pathway analysis reveals a role for the insulin receptor (IR)/insulin-like growth factor-1 receptor (IGF1R)/IRS2 signaling pathway in PILC. IRS2 mutations identified in PILC enhance invasion, revealing a role for this signaling adaptor in the aggressive nature of PILC. PMID:29669935

Vinpocetine protects inner retinal neurons with functional NMDA glutamate receptors against retinal ischemia.

PubMed

Nivison-Smith, Lisa; Khoo, Pauline; Acosta, Monica L; Kalloniatis, Michael

2018-02-01

Retinal ischemia is involved in the pathogenesis of many major vision threatening diseases. Vinpocetine is a natural drug, which has a range of neuroprotective actions against retinal ischemia including modulating cation flow, improving metabolic activity and preventing apoptosis. The exact mechanism behind these actions remains unknown but may involve glutamate receptors, major components of the ischemic cascade. This study examined the effects of vinpocetine in association with specific ionotropic glutamate receptor agonists: N-methyl-D-aspartate (NMDA) and kainate. Vinpocetine's actions to improve cation channel permeability and cell marker immunoreactivity following ischemia appeared to be limited to NMDA activation with no changes observed following kainate stimulation. Vinpocetine's actions were lost in the presence of an NMDA receptor inhibitor further suggesting they may be secondary to NMDA receptor activation. NMDA receptor function was also necessary for vinpocetine's actions on glucose availability during ischemia but not lactate dehydrogenase (LDH) activity in the ischemic retina suggesting not all of vinpocetine's actions are linked to NMDA receptor function. These results may explain vinpocetine's effectiveness as a neuroprotective agent as the NMDA receptor is implicated in the pathogenesis of ischemia in a range of tissues of the central nervous system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cell-free synthesis of functional human epidermal growth factor receptor: Investigation of ligand-independent dimerization in Sf21 microsomal membranes using non-canonical amino acids

PubMed Central

Quast, Robert B.; Ballion, Biljana; Stech, Marlitt; Sonnabend, Andrei; Varga, Balázs R.; Wüstenhagen, Doreen A.; Kele, Péter; Schiller, Stefan M.; Kubick, Stefan

2016-01-01

Cell-free protein synthesis systems represent versatile tools for the synthesis and modification of human membrane proteins. In particular, eukaryotic cell-free systems provide a promising platform for their structural and functional characterization. Here, we present the cell-free synthesis of functional human epidermal growth factor receptor and its vIII deletion mutant in a microsome-containing system derived from cultured Sf21 cells. We provide evidence for embedment of cell-free synthesized receptors into microsomal membranes and asparagine-linked glycosylation. Using the cricket paralysis virus internal ribosome entry site and a repetitive synthesis approach enrichment of receptors inside the microsomal fractions was facilitated thereby providing analytical amounts of functional protein. Receptor tyrosine kinase activation was demonstrated by monitoring receptor phosphorylation. Furthermore, an orthogonal cell-free translation system that provides the site-directed incorporation of p-azido-L-phenylalanine is characterized and applied to investigate receptor dimerization in the absence of a ligand by photo-affinity cross-linking. Finally, incorporated azides are used to generate stable covalently linked receptor dimers by strain-promoted cycloaddition using a novel linker system. PMID:27670253

Characterization of rat leydig cell gonadotropin receptor structure by affinity cross-linking

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

Zhang, Q.Y.; Hwang, J.; Menon, K.M.J.

1986-05-01

The gonadotropin receptor from rat leydig cell has been characterized with respect to binding kinetics and physiological regulation. The present study was intended to examine the structure of the receptor. Leydig cell suspension was prepared by either collagenase digestion or by mechanical disruption of the testis. The cells were incubated with /sup 125/I-hCG and the unreacted hCG was removed by centrifugation. The /sup 125/I-hCG was then covalently linked to the cell surface receptor using cleavable (dithiobis (succinimidyl propionate)) and non-cleavable (disuccinimidyl suberate) cross-linking reagents. The extracted cross-linked membrane proteins were resolved on SDS-polyacrylamide gels under reducing and non-reducing conditions andmore » subjected to autoradiographic analysis. Under non-reducing conditions, two labeled species with M/sub r/ = 87,000 and 120,000 were detected. However, only one labeled band was detected under reducing conditions with M/sub r/ = 64,000. The binding of /sup 125/I-hCG to the receptor was inhibited by hCG and LH, but not by a number of peptides and proteins. The data suggest that hCG receptor in leydig cell is an oligomeric complex consisting of four subunits, ..cap alpha cap alpha beta gamma... The ..beta.. and ..gamma.. subunits are each linked to an ..cap alpha.. subunit through disulfide linkage and the hormone binds to each ..cap alpha.. subunit. The two dimers formed (..cap alpha beta cap alpha gamma..) are associated by noncovalent interactions.« less

Prolonged morphine treatment alters δ opioid receptor post-internalization trafficking

PubMed Central

Ong, E W; Xue, L; Olmstead, M C; Cahill, C M

2015-01-01

BACKGROUND AND PURPOSE The δ opioid receptor (DOP receptor) undergoes internalization both constitutively and in response to agonists. Previous work has shown that DOP receptors traffic from intracellular compartments to neuronal cell membranes following prolonged morphine treatment. Here, we examined the effects of prolonged morphine treatment on the post-internalization trafficking of DOP receptors. EXPERIMENTAL APPROACH Using primary cultures of dorsal root ganglia neurons, we measured the co-localization of endogenous DOP receptors with post-endocytic compartments following both prolonged and acute agonist treatments. KEY RESULTS A departure from the constitutive trafficking pathway was observed following acute DOP receptor agonist-induced internalization by deltorphin II. That is, the DOP receptor underwent distinct agonist-induced post-endocytic sorting. Following prolonged morphine treatment, constitutive DOP receptor trafficking was augmented. SNC80 following prolonged morphine treatment also caused non-constitutive DOP receptor agonist-induced post-endocytic sorting. The μ opioid receptor (MOP receptor) agonist DAMGO induced DOP receptor internalization and trafficking following prolonged morphine treatment. Finally, all of the alterations to DOP receptor trafficking induced by both DOP and MOP receptor agonists were inhibited or absent when those agonists were co-administered with a DOP receptor antagonist, SDM-25N. CONCLUSIONS AND IMPLICATIONS The results support the hypothesis that prolonged morphine treatment induces the formation of MOP–DOP receptor interactions and subsequent augmentation of the available cell surface DOP receptors, at least some of which are in the form of a MOP/DOP receptor species. The pharmacology and trafficking of this species appear to be unique compared to those of its individual constituents. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2 PMID:24819092

Central serotonin modulates neural responses to virtual violent actions in emotion regulation networks.

PubMed

Wolf, Dhana; Klasen, Martin; Eisner, Patrick; Zepf, Florian D; Zvyagintsev, Mikhail; Palomero-Gallagher, Nicola; Weber, René; Eisert, Albrecht; Mathiak, Klaus

2018-06-08

Disruptions in the cortico-limbic emotion regulation networks have been linked to depression, anxiety, impulsivity, and aggression. Altered transmission of the central nervous serotonin (5-HT) contributes to dysfunctions in the cognitive control of emotions. To date, studies relating to pharmaco-fMRI challenging of the 5-HT system have focused on emotion processing for facial expressions. We investigated effects of a single-dose selective 5-HT reuptake inhibitor (escitalopram) on emotion regulation during virtual violence. For this purpose, 38 male participants played a violent video game during fMRI scanning. The SSRI reduced neural responses to violent actions in right-hemispheric inferior frontal gyrus and medial prefrontal cortex encompassing the anterior cingulate cortex (ACC), but not to non-violent actions. Within the ACC, the drug effect differentiated areas with high inhibitory 5-HT1A receptor density (subgenual s25) from those with a lower density (pregenual p32, p24). This finding links functional responses during virtual violent actions with 5-HT neurotransmission in emotion regulation networks, underpinning the ecological validity of the 5-HT model in aggressive behavior. Available 5-HT receptor density data suggest that this SSRI effect is only observable when inhibitory and excitatory 5-HT receptors are balanced. The observed early functional changes may impact patient groups receiving SSRI treatment.

An emerging link between LIM domain proteins and nuclear receptors.

PubMed

Sala, Stefano; Ampe, Christophe

2018-06-01

Nuclear receptors are ligand-activated transcription factors that partake in several biological processes including development, reproduction and metabolism. Over the last decade, evidence has accumulated that group 2, 3 and 4 LIM domain proteins, primarily known for their roles in actin cytoskeleton organization, also partake in gene transcription regulation. They shuttle between the cytoplasm and the nucleus, amongst other as a consequence of triggering cells with ligands of nuclear receptors. LIM domain proteins act as important coregulators of nuclear receptor-mediated gene transcription, in which they can either function as coactivators or corepressors. In establishing interactions with nuclear receptors, the LIM domains are important, yet pleiotropy of LIM domain proteins and nuclear receptors frequently occurs. LIM domain protein-nuclear receptor complexes function in diverse physiological processes. Their association is, however, often linked to diseases including cancer.

Evidence for an asialoglycoprotein receptor on nonparenchymal cells for O-linked glycoproteins.

PubMed

Stefanich, Eric G; Ren, Song; Danilenko, Dimitry M; Lim, Amy; Song, An; Iyer, Suhasini; Fielder, Paul J

2008-11-01

B cell-activating factor receptor 3 (BR3)-Fc is an IgG1-receptor dimeric fusion protein that has multiple O-linked glycosylation sites and sialylation levels that can vary in the manufacturing process. Increased sialic acid levels resulted from increased site occupancy with the O-linked N-acetylgalactosamine (GalNAc-Gal), but because the ratio of sialic acid per mole of oligosaccharide remained approximately 1, this led to increased asialo terminal GalNAc. Previous studies have demonstrated an effect of terminal asialo Gal or GalNAc on the clearance of glycoproteins due to uptake and degradation by lectin receptors in the liver. However, the previous studies examined N-linked oligosaccharides, and there are less data regarding O-linked oligosaccharides. The objective of these studies was to determine the effects on the pharmacokinetics and distribution of the asialo terminal GalNAc and varying amounts of sialic acid residues on BR3-Fc. The results of the data presented here suggest that exposed Gal on the desialylated BR3-Fc led to rapid clearance due to uptake and degradation in the liver that was associated with nonparenchymal cells. It is interesting to note that the data indicated a decreased clearance and increased exposure of BR3-Fc as the sialic acid levels increased, even though increased sialic acid was associated with increased asialo GalNAc. Therefore, the exposed GalNAc did not seem to play a role in the clearance of BR3-Fc; although the Gal linked to the hydroxyl group at position 3 may have prevented an interaction. Because we did not see uptake of desialylated BR3-Fc in hepatocytes where the asialoglycoprotein receptor is localized, this nonparenchymal cell lectin may have preference for O-linked glycoproteins.

The A-chain of insulin contacts the insert domain of the insulin receptor. Photo-cross-linking and mutagenesis of a diabetes-related crevice.

PubMed

Huang, Kun; Chan, Shu Jin; Hua, Qing-xin; Chu, Ying-Chi; Wang, Run-ying; Klaproth, Birgit; Jia, Wenhua; Whittaker, Jonathan; De Meyts, Pierre; Nakagawa, Satoe H; Steiner, Donald F; Katsoyannis, Panayotis G; Weiss, Michael A

2007-11-30

The contribution of the insulin A-chain to receptor binding is investigated by photo-cross-linking and nonstandard mutagenesis. Studies focus on the role of Val(A3), which projects within a crevice between the A- and B-chains. Engineered receptor alpha-subunits containing specific protease sites ("midi-receptors") are employed to map the site of photo-cross-linking by an analog containing a photoactivable A3 side chain (para-azido-Phe (Pap)). The probe cross-links to a C-terminal peptide (residues 703-719 of the receptor A isoform, KTFEDYLHNVVFVPRPS) containing side chains critical for hormone binding (underlined); the corresponding segment of the holoreceptor was shown previously to cross-link to a Pap(B25)-insulin analog. Because Pap is larger than Val and so may protrude beyond the A3-associated crevice, we investigated analogs containing A3 substitutions comparable in size to Val as follows: Thr, allo-Thr, and alpha-aminobutyric acid (Aba). Substitutions were introduced within an engineered monomer. Whereas previous studies of smaller substitutions (Gly(A3) and Ser(A3)) encountered nonlocal conformational perturbations, NMR structures of the present analogs are similar to wild-type insulin; the variant side chains are accommodated within a native-like crevice with minimal distortion. Receptor binding activities of Aba(A3) and allo-Thr(A3) analogs are reduced at least 10-fold; the activity of Thr(A3)-DKP-insulin is reduced 5-fold. The hormone-receptor interface is presumably destabilized either by a packing defect (Aba(A3)) or by altered polarity (allo-Thr(A3) and Thr(A3)). Our results provide evidence that Val(A3), a site of mutation causing diabetes mellitus, contacts the insert domain-derived tail of the alpha-subunit in a hormone-receptor complex.

Graves' disease: diagnostic and therapeutic challenges (multimedia activity).

PubMed

Kahaly, George J; Grebe, Stefan K G; Lupo, Mark A; McDonald, Nicole; Sipos, Jennifer A

2011-06-01

Graves' disease is the most common cause of hyperthyroidism in the United States. Graves' disease occurs more often in women with a female:male ratio of 5:1 and a population prevalence of 1% to 2%. A genetic determinant to the susceptibility to Graves' disease is suspected because of familial clustering of the disease, a high sibling recurrence risk, the familial occurrence of thyroid autoantibodies, and the 30% concordance in disease status between identical twins. Graves' disease is an autoimmune thyroid disorder characterized by the infiltration of immune effector cells and thyroid antigen-specific T cells into the thyroid and thyroid-stimulating hormone receptor expressing tissues, with the production of autoantibodies to well-defined thyroidal antigens, such as thyroid peroxidase, thyroglobulin, and the thyroid-stimulating hormone receptor. The thyroid-stimulating hormone receptor is central to the regulation of thyroid growth and function. Stimulatory autoantibodies in Graves' disease activate the thyroid-stimulating hormone receptor leading to thyroid hyperplasia and unregulated thyroid hormone production and secretion. Below-normal levels of baseline serum thyroid-stimulating hormone receptor, normal to elevated serum levels of T4, elevated serum levels of T3 and thyroid-stimulating hormone receptor autoantibodies, and a diffusely enlarged, heterogeneous, hypervascular (increased Doppler flow) thyroid gland confirm diagnosis of Graves' disease (available at: http://supplements.amjmed.com/2010/hyperthyroid/faculty.php). This Resource Center is also available through the website of The American Journal of Medicine (www.amjmed.com). Click on the “Thyroid/Graves' Disease” link in the “Resource Centers” section, found on the right side of the Journal homepage. Copyright © 2011 Elsevier Inc. All rights reserved.

Dysregulation of D2-Mediated Dopamine Transmission in Monkeys after Chronic Escalating Methamphetamine Exposure

PubMed Central

Groman, S.M.; Lee, B.; Seu, E.; James, A.S.; Feiler, K.; Mandelkern, M.A.; London, E.D.; Jentsch, J.D.

2012-01-01

Compulsive drug-seeking and drug-taking are important substance-abuse behaviors that have been linked to alterations in dopaminergic neurotransmission and to impaired inhibitory control. Evidence supports the notions that abnormal D2 receptor-mediated dopamine transmission and inhibitory control may be heritable risk factors for addictions, and that they also reflect drug-induced neuroadaptations. To provide a mechanistic explanation for the drug-induced emergence of inhibitory-control deficits, this study examined how a chronic, escalating-dose regimen of methamphetamine administration affected dopaminergic neurochemistry and cognition in monkeys. Dopamine D2-like receptor and dopamine transporter (DAT) availability and reversal-learning performance were measured before and after exposure to methamphetamine (or saline), and brain dopamine levels were assayed at the conclusion of the study. Exposure to methamphetamine reduced dopamine D2-like receptor and DAT availability, and produced transient, selective impairments in the reversal of a stimulus-outcome association. Furthermore, individual differences in the change in D2-like receptor availability in the striatum were related to the change in response to positive feedback. These data provide evidence that chronic, escalating-dose methamphetamine administration alters the dopamine system in a manner similar to that observed in methamphetamine-dependent humans. They also implicate alterations in positive-feedback sensitivity associated with D2-like receptor dysfunction as the mechanism by which inhibitory control deficits emerge in stimulant-dependent individuals. Finally, a significant degree of neurochemical and behavioral variation in response to methamphetamine was detected, indicating that individual differences affect the degree to which drugs of abuse alter these processes. Identification of these factors ultimately may assist in the development of individualized treatments for substance dependence. PMID:22539846

Dysregulation of D₂-mediated dopamine transmission in monkeys after chronic escalating methamphetamine exposure.

PubMed

Groman, Stephanie M; Lee, Buyean; Seu, Emanuele; James, Alex S; Feiler, Karen; Mandelkern, Mark A; London, Edythe D; Jentsch, J David

2012-04-25

Compulsive drug-seeking and drug-taking are important substance-abuse behaviors that have been linked to alterations in dopaminergic neurotransmission and to impaired inhibitory control. Evidence supports the notions that abnormal D₂ receptor-mediated dopamine transmission and inhibitory control may be heritable risk factors for addictions, and that they also reflect drug-induced neuroadaptations. To provide a mechanistic explanation for the drug-induced emergence of inhibitory-control deficits, this study examined how a chronic, escalating-dose regimen of methamphetamine administration affected dopaminergic neurochemistry and cognition in monkeys. Dopamine D₂-like receptor and dopamine transporter (DAT) availability and reversal-learning performance were measured before and after exposure to methamphetamine (or saline), and brain dopamine levels were assayed at the conclusion of the study. Exposure to methamphetamine reduced dopamine D₂-like receptor and DAT availability and produced transient, selective impairments in the reversal of a stimulus-outcome association. Furthermore, individual differences in the change in D₂-like receptor availability in the striatum were related to the change in response to positive feedback. These data provide evidence that chronic, escalating-dose methamphetamine administration alters the dopamine system in a manner similar to that observed in methamphetamine-dependent humans. They also implicate alterations in positive-feedback sensitivity associated with D₂-like receptor dysfunction as the mechanism by which inhibitory control deficits emerge in stimulant-dependent individuals. Finally, a significant degree of neurochemical and behavioral variation in response to methamphetamine was detected, indicating that individual differences affect the degree to which drugs of abuse alter these processes. Identification of these factors ultimately may assist in the development of individualized treatments for substance dependence.

Anticonvulsant activity of artificial sweeteners: a structural link between sweet-taste receptor T1R3 and brain glutamate receptors.

PubMed

Talevi, Alan; Enrique, Andrea V; Bruno-Blanch, Luis E

2012-06-15

A virtual screening campaign based on application of a topological discriminant function capable of identifying novel anticonvulsant agents indicated several widely-used artificial sweeteners as potential anticonvulsant candidates. Acesulfame potassium, cyclamate and saccharin were tested in the Maximal Electroshock Seizure model (mice, ip), showing moderate anticonvulsant activity. We hypothesized a probable structural link between the receptor responsible of sweet taste and anticonvulsant molecular targets. Bioinformatic tools confirmed a highly significant sequence-similarity between taste-related protein T1R3 and several metabotropic glutamate receptors from different species, including glutamate receptors upregulated in epileptogenesis and certain types of epilepsy. Copyright © 2012 Elsevier Ltd. All rights reserved.

A Protein Microarray ELISA for the Detection of Botulinum neurotoxin A

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

Varnum, Susan M.

An enzyme-linked immunosorbent assay (ELISA) microarray was developed for the specific and sensitive detection of botulinum neurotoxin A (BoNT/A), using high-affinity recombinant monoclonal antibodies against the receptor binding domain of the heavy chain of BoNT/A. The ELISA microarray assay, because of its sensitivity, offers a screening test with detection limits comparable to the mouse bioassay, with results available in hours instead of days.

Phosphoinositide system-linked serotonin receptor subtypes and their pharmacological properties and clinical correlates.

PubMed Central

Pandey, S C; Davis, J M; Pandey, G N

1995-01-01

Serotonergic neurotransmission represents a complex mechanism involving pre- and post-synaptic events and distinct 5-HT receptor subtypes. Serotonin (5-HT) receptors have been classified into several categories, and they are termed as 5-HT1, 5-HT2, 5-HT3, 5-HT4, 5-HT5, 5-HT6 and 5-HT7 type receptors. 5-HT1 receptors have been further subdivided into 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E and 5-HT1F. 5-HT2 receptors have been divided into 5-HT2A, 5-HT2B and 5-HT2C receptors. All 5-HT2 receptor subtypes are linked to the multifunctional phosphoinositide (PI) signalling system. 5-HT3 receptors are considered ion-gated receptors and are also linked to the PI signalling system by an unknown mechanism. The 5-HT2A receptor subtype is the most widely studied of the 5-HT receptors in psychiatric disorders (for example, suicide, depression and schizophrenia) as well as in relation to the mechanism of action of antidepressant drugs. The roles of 5-HT2C and 5-HT3 receptors in psychiatric disorders are less clear. These 5-HT receptors also play an important role in alcoholism. It has been shown that 5-HT2A, 5-HT2C and 5-HT3 antagonists cause attenuation of alcohol intake in animals and humans. However, the exact mechanisms are unknown. The recent cloning of the cDNAs for 5-HT2A, 5-HT2C and 5-HT3 receptors provides the opportunity to explore the molecular mechanisms responsible for the alterations in these receptors during illness as well as pharmacotherapy. This review article will focus on the current research into the pharmacological properties, molecular biology, and clinical correlates of 5-HT2A, 5-HT2C and 5-HT3 receptors. PMID:7786883

A network of autism linked genes stabilizes two pools of synaptic GABAA receptors

PubMed Central

Tong, Xia-Jing; Hu, Zhitao; Liu, Yu; Anderson, Dorian; Kaplan, Joshua M

2015-01-01

Changing receptor abundance at synapses is an important mechanism for regulating synaptic strength. Synapses contain two pools of receptors, immobilized and diffusing receptors, both of which are confined to post-synaptic elements. Here we show that immobile and diffusing GABAA receptors are stabilized by distinct synaptic scaffolds at C. elegans neuromuscular junctions. Immobilized GABAA receptors are stabilized by binding to FRM-3/EPB4.1 and LIN-2A/CASK. Diffusing GABAA receptors are stabilized by the synaptic adhesion molecules Neurexin and Neuroligin. Inhibitory post-synaptic currents are eliminated in double mutants lacking both scaffolds. Neurexin, Neuroligin, and CASK mutations are all linked to Autism Spectrum Disorders (ASD). Our results suggest that these mutations may directly alter inhibitory transmission, which could contribute to the developmental and cognitive deficits observed in ASD. DOI: http://dx.doi.org/10.7554/eLife.09648.001 PMID:26575289

Structural analysis and localization of the carbohydrate moieties of a soluble human interferon gamma receptor produced in baculovirus-infected insect cells.

PubMed Central

Manneberg, M.; Friedlein, A.; Kurth, H.; Lahm, H. W.; Fountoulakis, M.

1994-01-01

A soluble form of the human interferon gamma receptor that is required for the identification of interferon gamma antagonists was expressed in baculovirus-infected insect cells. The protein carried N-linked carbohydrate and showed a heterogeneity on denaturing polyacrylamide gels. We investigated the utilization of the potential sites for N-linked glycosylation and the structure of the carbohydrate moieties of this soluble receptor. Amino acid sequence analysis and ion spray mass spectrometry revealed that of the five potential sites for N-linked glycosylation, Asn17 and Asn69 were always utilized, whereas Asn62 and Asn162 were utilized in approximately one-third of the protein population. Asn223 was never found to be glycosylated. The soluble receptor was treated with N-glycosidase F and the oligosaccharides released were analyzed by matrix-assisted laser desorption mass spectrometry, which showed that the protein carried six types of short carbohydrate chains. The predominant species was a hexasaccharide of molecular mass 1,039, containing a fucose subunit linked to the proximal N-acetylglucosamine residue: [formula: see text] PMID:8142896

Preferential recognition of avian-like receptors in human influenza A H7N9 viruses.

PubMed

Xu, Rui; de Vries, Robert P; Zhu, Xueyong; Nycholat, Corwin M; McBride, Ryan; Yu, Wenli; Paulson, James C; Wilson, Ian A

2013-12-06

The 2013 outbreak of avian-origin H7N9 influenza in eastern China has raised concerns about its ability to transmit in the human population. The hemagglutinin glycoprotein of most human H7N9 viruses carries Leu(226), a residue linked to adaptation of H2N2 and H3N2 pandemic viruses to human receptors. However, glycan array analysis of the H7 hemagglutinin reveals negligible binding to humanlike α2-6-linked receptors and strong preference for a subset of avian-like α2-3-linked glycans recognized by all avian H7 viruses. Crystal structures of H7N9 hemagglutinin and six hemagglutinin-glycan complexes have elucidated the structural basis for preferential recognition of avian-like receptors. These findings suggest that the current human H7N9 viruses are poorly adapted for efficient human-to-human transmission.

Link between D sub 1 and D sub 2 dopamine receptors is reduced in schizophrenia and Huntington diseased brain

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

Seeman, P.; Niznik, H.B.; Guan, H.C.

1989-12-01

Dopamine receptor types D{sub 1} and D{sub 2} can oppose enhance each other's actions for electrical, biochemical, and psychomotor effects. The authors report a D{sub 1}-D{sub 2} interaction in homogenized tissue as revealed by ligand binding. D{sub 2} agonists lowered the binding of ({sup 3}H)raclopride to D{sub 2} receptors in striatal and anterior pituitary tissues. Pretreating the tissue with the D{sub 1}-selective antagonist SCH 23390 prevented the agonist-induced decrease in ({sup 3}H)raclopride binding to D{sub 2} sites in the striatum but not in the anterior pituitary, which has no D{sub 1} receptors. Conversely, a dopamine-induced reduction in the binding ofmore » ({sup 3}H)SCH 23390 to D{sub 1} receptors could be prevented by the D{sub 2}-selective antagonist eticlopride. Receptor photolabeling experiments confirmed both these D{sub 1}-D{sub 2} interactions. The blocking effect by SCH 23390 was similar to that produced by a nonhydrolyzable guanine nucleotide analogue, and SCH 23390 reduced the number of agonist-labeled D{sub 2} receptors in the high-affinity state. Thus, the D{sub 1}-D{sub 2} link may be mediated by guanine nucleotide-binding protein components. The link may underlie D{sub 1}-D{sub 2} interactions influencing behavior, since the link was missing in over half the postmortem striata from patients with schizophrenia and Huntington disease (both diseases that show some hyperdopamine signs) but was present in human control, Alzheimer, and Parkinson striata.« less

GPCR ontology: development and application of a G protein-coupled receptor pharmacology knowledge framework.

PubMed

Przydzial, Magdalena J; Bhhatarai, Barun; Koleti, Amar; Vempati, Uma; Schürer, Stephan C

2013-12-15

Novel tools need to be developed to help scientists analyze large amounts of available screening data with the goal to identify entry points for the development of novel chemical probes and drugs. As the largest class of drug targets, G protein-coupled receptors (GPCRs) remain of particular interest and are pursued by numerous academic and industrial research projects. We report the first GPCR ontology to facilitate integration and aggregation of GPCR-targeting drugs and demonstrate its application to classify and analyze a large subset of the PubChem database. The GPCR ontology, based on previously reported BioAssay Ontology, depicts available pharmacological, biochemical and physiological profiles of GPCRs and their ligands. The novelty of the GPCR ontology lies in the use of diverse experimental datasets linked by a model to formally define these concepts. Using a reasoning system, GPCR ontology offers potential for knowledge-based classification of individuals (such as small molecules) as a function of the data. The GPCR ontology is available at http://www.bioassayontology.org/bao_gpcr and the National Center for Biomedical Ontologies Web site.

The biology of the peroxisome proliferator-activated receptor system in the female reproductive tract.

PubMed

Vélez, Leandro Martín; Abruzzese, Giselle Adriana; Motta, Alicia Beatriz

2013-01-01

Fuel sensors such as glucose, insulin or leptin, are known to be directly involved in the regulation of fertility at each level of the hypothalamic-pituitary-gonadal axis. The discovery of the peroxisome proliferator-activated receptor (PPAR) family of transcription factors has revealed the link between lipid/glucose availability and long-term metabolic adaptation. By binding to specific regions of DNA in heterodimers with the retinoid X receptors (RXRs), the members of the PPAR family (α, β/δ, γ) are able to regulate the gene expressions of several key regulators of energy homeostasis including several glucose regulators (glucose transporters, insulin receptor, substrate insulin receptor, etc), and also metabolic and endocrine pathways like lipogenesis, steroidogenesis, ovulation, oocyte maturation, maintenance of the corpus luteum, nitric oxide system, several proteases and plasminogen activator among others. All the three PPAR isoforms are expressed in different tissues of the female reproductive tract and regulate gametogenesis, ovulation, corpus luteum regression and the implantation process among others. The present review discusses the mechanisms involved in PPAR activation focusing on endogenous and synthetic ligands of PPAR not only in physiological but also in pathological conditions (such as polycystic ovary syndrome, pathologies of implantation process, chronic anovulation, etc).

Biotin-transfer from a trifunctional crosslinker for identification of cell surface receptors of soluble protein ligands

PubMed Central

Tremblay, Tammy-Lynn; Hill, Jennifer J.

2017-01-01

Here we describe a novel crosslinker and its application as a biotin-transfer reagent to identify cell surface receptors of soluble protein ligands on live cells. This crosslinker contains three functional groups: an aldehyde-reactive aminooxy group, a sulfhydryl, and a biotin (ASB). It is readily synthesized via a 3-step addition reaction using standard solid-phase peptide synthesis methods and commercially available intermediates, allowing access to laboratories without specialized synthetic chemistry capabilities. For the biotin-transfer method, ASB is linked to a protein ligand through the sulfhydryl group in a two-step process that allows the introduction of a disulfide bond between the ligand and the crosslinker. Incubation of the labelled ligand with oxidized live cells leads to the formation of crosslinks with aldehyde-containing glycans on the cell surface receptor. Subsequent reduction of the disulfide bond results in biotin transfer from the ligand to the cell surface receptor. Protein biotinylation that is mediated by ligand binding to its receptor is differentiated from background biotinylation events by comparison with a similarly labelled control protein using comparative proteomic mass spectrometry to quantify streptavidin-bound proteins. Using this method, we successfully identified the cell surface receptors of a peptide hormone, a monoclonal antibody, and a single-domain antibody-Fc fusion construct. PMID:28422167

N-Linked Glycosylation and Sequence Changes in a Critical Negative Control Region of the ASCT1 and ASCT2 Neutral Amino Acid Transporters Determine Their Retroviral Receptor Functions

PubMed Central

Marin, Mariana; Lavillette, Dimitri; Kelly, Sean M.; Kabat, David

2003-01-01

A widely dispersed interference group of retroviruses that includes the feline endogenous virus (RD114), baboon endogenous virus (BaEV), human endogenous virus type W (HERV-W), and type D primate retroviruses uses the human Na+-dependent neutral amino acid transporter type 2 (hASCT2; gene name, SLC1A5) as a common cell surface receptor. Although hamster cells are fully resistant to these viruses and murine cells are susceptible only to BaEV and HERV-W pseudotype viruses, these rodent cells both become highly susceptible to all of the viruses after treatment with tunicamycin, an inhibitor of protein N-linked glycosylation. A partial explanation for these results was recently provided by findings that the orthologous murine transporter mASCT2 is inactive as a viral receptor, that a related (ca. 55% identity) murine paralog (mASCT1; gene name, SLC1A4) mediates infections specifically of BaEV and HERV-W, and that N-deglycosylation of mASCT1 activates it as a receptor for all viruses of this interference group. Because the only two N-linked oligosaccharides in mASCT1 occur in the carboxyl-terminal region of extracellular loop 2 (ECL2), it was inferred that this region contributes in an inhibitory manner to infections by RD114 and type D primate viruses. To directly and more thoroughly investigate the receptor active sites, we constructed and analyzed a series of hASCT2/mASCT2 chimeras and site-directed mutants. Our results suggest that a hypervariable sequence of 21 amino acids in the carboxyl-terminal portion of ECL2 plays a critical role in determining the receptor properties of ASCT2 proteins for all viruses in this interference group. In addition, we analyzed the tunicamycin-dependent viral susceptibility of hamster cells. In contrast to mASCT1, which contains two N-linked oligosaccharides that partially restrict viral infections, hamster ASCT1 contains an additional N-linked oligosaccharide clustered close to the others in the carboxyl-terminal region of ECL2. Removal of this N-linked oligosaccharide by mutagenesis enabled hamster ASCT1 to function as a receptor for all viruses of this interference group. These results strongly suggest that combinations of amino acid sequence changes and N-linked oligosaccharides in a critical carboxyl-terminal region of ECL2 control retroviral utilization of both the ASCT1 and ASCT2 receptors. PMID:12584318

Emotion dysregulation and amygdala dopamine D2-type receptor availability in methamphetamine users.

PubMed

Okita, Kyoji; Ghahremani, Dara G; Payer, Doris E; Robertson, Chelsea L; Dean, Andy C; Mandelkern, Mark A; London, Edythe D

2016-04-01

Individuals who use methamphetamine chronically exhibit emotional and dopaminergic neurochemical deficits. Although the amygdala has an important role in emotion processing and receives dopaminergic innervation, little is known about how dopamine transmission in this region contributes to emotion regulation. This investigation aimed to evaluate emotion regulation in subjects who met DSM-IV criteria for methamphetamine dependence, and to test for a relationship between self-reports of difficulty in emotion regulation and D2-type dopamine receptor availability in the amygdala. Ninety-four methamphetamine-using and 102 healthy-control subjects completed the Difficulties in Emotion Regulation Scale (DERS); 33 of those who used methamphetamine completed the Addiction Severity Index (ASI). A subset of 27 methamphetamine-group and 20 control-group subjects completed positron emission tomography with [(18)F]fallypride to assay amygdala D2-type dopamine receptor availability, measured as binding potential (BPND). The methamphetamine group scored higher than the control group on the DERS total score (p<0.001), with DERS total score positively correlated with the Drug Composite Score on the ASI (p=0.02) in the methamphetamine group. The DERS total score was positively correlated with amygdala BPND in both groups and the combined group of participants (combined: r=0.331, p=0.02), and the groups did not differ in this relationship. These findings highlight problems with emotion regulation linked to methamphetamine use, possibly contributing to personal and interpersonal behavioral problems. They also suggest that D2-type dopamine receptors in the amygdala contribute to emotion regulation in both healthy and methamphetamine-using subjects. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Emotion Dysregulation and Amygdala Dopamine D2-type Receptor Availability in Methamphetamine Users

PubMed Central

Okita, Kyoji; Ghahremani, Dara G.; Payer, Doris E.; Robertson, Chelsea L.; Dean, Andy C.; Mandelkern, Mark A.; London, Edythe D.

2016-01-01

Background Individuals who use methamphetamine chronically exhibit emotional and dopaminergic neurochemical deficits. Although the amygdala has an important role in emotion processing and receives dopaminergic innervation, little is known about how dopamine transmission in this region contributes to emotion regulation. This investigation aimed to evaluate emotion regulation in subjects who met DSM-IV criteria for methamphetamine dependence, and to test for a relationship between self-reports of difficulty in emotion regulation and D2-type dopamine receptor availability in the amygdala. Method Ninety-four methamphetamine-using and 102 healthy-control subjects completed the Difficulties in Emotion Regulation Scale (DERS); 33 of those who used methamphetamine completed the Addiction Severity Index (ASI). A subset of 27 methamphetamine-group and 20 control-group subjects completed positron emission tomography with [18F]fallypride to assay amygdala D2-type dopamine receptor availability, measured as binding potential (BPND). Results The methamphetamine group scored higher than the control group on the DERS total score (p < 0.001), with DERS total score positively correlated with the Drug Composite Score on the ASI (p = 0.02) in the methamphetamine group. The DERS total score was positively correlated with amygdala BPND in both groups and the combined group of participants (combined: r = 0.331, p = 0.02), and the groups did not differ in this relationship. Conclusion These findings highlight problems with emotion regulation linked to methamphetamine use, possibly contributing to personal and interpersonal behavioral problems. They also suggest that D2-type dopamine receptors in the amygdala contribute to emotion regulation in both healthy and methamphetamine-using subjects. PMID:26880595

The Concise Guide to Pharmacology 2013/14: G Protein-Coupled Receptors

PubMed Central

Alexander, Stephen PH; Benson, Helen E; Faccenda, Elena; Pawson, Adam J; Sharman, Joanna L; Spedding, Michael; Peters, John A; Harmar, Anthony J

2013-01-01

The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. G protein-coupled receptors are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates. PMID:24517644

A role for Pyk2 and Src in linking G-protein-coupled receptors with MAP kinase activation.

PubMed

Dikic, I; Tokiwa, G; Lev, S; Courtneidge, S A; Schlessinger, J

1996-10-10

The mechanisms by which mitogenic G-protein-coupled receptors activate the MAP kinase signalling pathway are poorly understood. Candidate protein tyrosine kinases that link G-protein-coupled receptors with MAP kinase include Src family kinases, the epidermal growth factor receptor, Lyn and Syk. Here we show that lysophosphatidic acid (LPA) and bradykinin induce tyrosine phosphorylation of Pyk2 and complex formation between Pyk2 and activated Src. Moreover, tyrosine phosphorylation of Pyk2 leads to binding of the SH2 domain of Src to tyrosine 402 of Pyk2 and activation of Src. Transient overexpression of a dominant interfering mutant of Pyk2 or the protein tyrosine kinase Csk reduces LPA- or bradykinin-induced activation of MAP kinase. LPA- or bradykinin-induced MAP kinase activation was also inhibited by overexpression of dominant interfering mutants of Grb2 and Sos. We propose that Pyk2 acts with Src to link Gi- and Gq-coupled receptors with Grb2 and Sos to activate the MAP kinase signalling pathway in PC12 cells.

Analysis of ligand-receptor cross-linked fragments by mass spectrometry

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

Son, C.D.; Sargsyan, H.; Hurst, Gregory

G-protein coupled receptors (GPCRs) are a class of integral membrane receptor proteins that are characterized by a signature seven-transmembrane (7-TM) configuration. The a-factor receptor (Ste2p) from Saccharomyces cerevisiae is a GPCR that, upon binding of a peptide ligand, transduces a signal to initiate a cascade of events leading to the mating of haploid yeast cells. This study summarizes the application of affinity purification and of matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) experiments using biotinylated photoactivatable a-factor analogs. Affinity purification and enrichment of biotinylated peptides by monomeric avidin beads resulted in mass spectrometric detection of specific signals corresponding to crosslinked fragments ofmore » Ste2p. Data obtained from cyanogen bromide (CNBr) fragments of receptor cross-linked to an a-factor analog with the photoaffinity group p-benzoyl-L-phenylalanine on position 1 were in agreement with the previous results reported by our laboratory suggesting the cross-linking between position 1 of a-factor and a region of Ste2p covering residues 251 294.« less

Methylation of the Glucocorticoid Receptor Gene Promoter in Preschoolers: Links with Internalizing Behavior Problems

ERIC Educational Resources Information Center

Parade, Stephanie H.; Ridout, Kathryn K.; Seifer, Ronald; Armstrong, David A.; Marsit, Carmen J.; McWilliams, Melissa A.; Tyrka, Audrey R.

2016-01-01

Accumulating evidence suggests that early adversity is linked to methylation of the glucocorticoid receptor (GR) gene, "NR3C1," which is a key regulator of the hypothalamic-pituitary-adrenal axis. Yet no prior work has considered the contribution of methylation of "NR3C1" to emerging behavior problems and psychopathology in…

Changes of several brain receptor complexes in the cerebral cortex of patients with Alzheimer disease: probable new potential pharmaceutical targets.

PubMed

Falsafi, Soheil Keihan; Roßner, Steffen; Ghafari, Maryam; Groessl, Michael; Morawski, Markus; Gerner, Christopher; Lubec, Gert

2014-01-01

Although Alzheimer disease (AD) has been linked to defects in major brain receptors, studies thus far have been limited to the determination of receptor subunits or specific ligand binding studies. However, the availability of current technology enables the determination and quantification of brain receptor complexes. Thus, we examined levels of native receptor complexes in the brains of patients with AD. Cortical tissue was obtained from control subjects (n = 12 females and 12 males) and patients with AD (n = 12 females and 12 males) within a 3-h postmortem time period. The tissues were kept frozen until further biochemical analyses. Membrane proteins were extracted and subsequently enriched by ultracentrifugation using a sucrose gradient. Membrane proteins were then electrophoresed onto native gels and immunoblotted using antibodies against individual brain receptors. We found that the levels were comparable for complexes containing GluR2, GluR3 and GluR4 as well as 5-HT1A. Moreover, the levels of complexes containing muscarinic AChR M1, NR1 and GluR1 were significantly increased in male patients with AD. Nicotinic AChRs 4 and 7 as well as dopaminergic receptors D1 and D2 were also increased in males and females with AD. These findings reveal a pattern of altered receptor complex levels that may contribute to the deterioration of the concerted activity of these receptors and thus result in cognitive deficits observed in patients with AD. It should be emphasised that receptor complexes function as working units rather than individual subunits. Thus, the receptor deficits identified may be relevant for the design of experimental therapies. Therefore, specific pharmacological modulation of these receptors is within the pharmaceutical repertoire.

N-linked glycosylation of cortical N-methyl-D-aspartate and kainate receptor subunits in schizophrenia.

PubMed

Tucholski, Janusz; Simmons, Micah S; Pinner, Anita L; McMillan, Laurence D; Haroutunian, Vahram; Meador-Woodruff, James H

2013-08-21

Dysfunctional glutamate neurotransmission has been implicated in the pathophysiology of schizophrenia. Abnormal expressions in schizophrenia of ionotropic glutamate receptors (iGluRs) and the proteins that regulate their trafficking have been found to be region and subunit specific in brain, suggesting that abnormal trafficking of iGluRs may contribute toward altered glutamatergic neurotransmission. The post-translational modification N-glycosylation of iGluR subunits can be used as a proxy for their intracellular localization. Receptor complexes assemble in the lumen of the endoplasmic reticulum, where N-glycosylation begins with the addition of N-linked oligomannose glycans, and is subsequently trimmed and replaced by more elaborate glycans while trafficking through the Golgi apparatus. Previously, we found abnormalities in N-glycosylation of the GluR2 AMPA receptor subunit in schizophrenia. Here, we investigated N-glycosylation of N-methyl-D-aspartate and kainate (KA) receptor subunits in the dorsolateral prefrontal cortex from patients with schizophrenia and a comparison group. We used enzymatic deglycosylation with two glycosidases: endoglycosidase H (Endo H), which removes immature high mannose-containing sugars, and peptide-N-glycosidase F (PNGase F), which removes all N-linked sugars. The NR1, NR2A, NR2B, GluR6, and KA2 subunits were all sensitive to treatment with Endo H and PNGase F. The GluR6 KA receptor subunit was significantly more sensitive to Endo H-mediated deglycosylation in schizophrenia, suggesting a larger molecular mass of N-linked high mannose and/or hybrid sugars on GluR6. This finding, taken with our previous work, suggests that a cellular mechanism underlying abnormal glutamate neurotransmission in schizophrenia may involve abnormal trafficking of both AMPA and KA receptors.

The sweet taste quality is linked to a cluster of taste fibers in primates: lactisole diminishes preference and responses to sweet in S fibers (sweet best) chorda tympani fibers of M. fascicularis monkey.

PubMed

Wang, Yiwen; Danilova, Vicktoria; Cragin, Tiffany; Roberts, Thomas W; Koposov, Alexey; Hellekant, Göran

2009-02-18

Psychophysically, sweet and bitter have long been considered separate taste qualities, evident already to the newborn human. The identification of different receptors for sweet and bitter located on separate cells of the taste buds substantiated this separation. However, this finding leads to the next question: is bitter and sweet also kept separated in the next link from the taste buds, the fibers of the taste nerves? Previous studies in non-human primates, P. troglodytes, C. aethiops, M. mulatta, M. fascicularis and C. jacchus, suggest that the sweet and bitter taste qualities are linked to specific groups of fibers called S and Q fibers. In this study we apply a new sweet taste modifier, lactisole, commercially available as a suppressor of the sweetness of sugars on the human tongue, to test our hypothesis that sweet taste is conveyed in S fibers. We first ascertained that lactisole exerted similar suppression of sweetness in M. fascicularis, as reported in humans, by recording their preference of sweeteners and non- sweeteners with and without lactisole in two-bottle tests. The addition of lactisole significantly diminished the preference for all sweeteners but had no effect on the intake of non-sweet compounds or the intake of water. We then recorded the response to the same taste stimuli in 40 single chorda tympani nerve fibers. Comparison between single fiber nerve responses to stimuli with and without lactisole showed that lactisole only suppressed the responses to sweeteners in S fibers. It had no effect on the responses to any other stimuli in all other taste fibers. In M. fascicularis, lactisole diminishes the attractiveness of compounds, which taste sweet to humans. This behavior is linked to activity of fibers in the S-cluster. Assuming that lactisole blocks the T1R3 monomer of the sweet taste receptor T1R2/R3, these results present further support for the hypothesis that S fibers convey taste from T1R2/R3 receptors, while the impulse activity in non-S fibers originates from other kinds of receptors. The absence of the effect of lactisole on the faint responses in some S fibers to other stimuli as well as the responses to sweet and non-sweet stimuli in non-S fibers suggest that these responses originate from other taste receptors.

Structural Characterization of the Hemagglutinin Receptor Specificity from the 2009 H1N1 Influenza Pandemic

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

Xu, Rui; McBride, Ryan; Nycholat, Corwin M.

2012-02-13

Influenza virus hemagglutinin (HA) is the viral envelope protein that mediates viral attachment to host cells and elicits membrane fusion. The HA receptor-binding specificity is a key determinant for the host range and transmissibility of influenza viruses. In human pandemics of the 20th century, the HA normally has acquired specificity for human-like receptors before widespread infection. Crystal structures of the H1 HA from the 2009 human pandemic (A/California/04/2009 [CA04]) in complex with human and avian receptor analogs reveal conserved recognition of the terminal sialic acid of the glycan ligands. However, favorable interactions beyond the sialic acid are found only formore » {alpha}2-6-linked glycans and are mediated by Asp190 and Asp225, which hydrogen bond with Gal-2 and GlcNAc-3. For {alpha}2-3-linked glycan receptors, no specific interactions beyond the terminal sialic acid are observed. Our structural and glycan microarray analyses, in the context of other high-resolution HA structures with {alpha}2-6- and {alpha}2-3-linked glycans, now elucidate the structural basis of receptor-binding specificity for H1 HAs in human and avian viruses and provide a structural explanation for the preference for {alpha}2-6 siaylated glycan receptors for the 2009 pandemic swine flu virus.« less

Biosynthesis and processing of the mannose receptor in human macrophages.

PubMed

Lennartz, M R; Cole, F S; Stahl, P D

1989-02-05

The biosynthesis and processing of the human mannose receptor has been studied in monocyte-derived macrophages. Adherent cells were labeled for 60 min with Trans35S (a mixture of 35S-labeled methionine and cysteine), chased, and subjected to immunoprecipitation by antibody raised against the human placental receptor. The antibody immunoprecipitated a single protein of molecular mass 162 kDa; precipitation of the labeled receptor could be inhibited by placental receptor. The results presented demonstrate that the receptor is synthesized as a 154-kDa precursor which is processed to 162 kDa in 90 min. The precursor is a glycoprotein bearing endoglycosidase H-sensitive oligosaccharides; the 162-kDa form is endoglycosidase H-resistant but peptide:N-glycanase-sensitive. Desialylation of the mannose receptor with neuraminidase generates a protein which is recognized by peanut agglutinin, a lectin that specifically binds desialylated O-linked oligosaccharides. Thus, the human macrophage mannose receptor bears both N- and O-linked oligosaccharide chains. Newly synthesized mannose receptor exhibits a half-life of 33 h as determined by pulse-chase studies. This indicates that on the average, each molecule of receptor recycles between the cell surface and endosomes hundreds of times before degradation.

Effects of inhibitors of N-linked oligosaccharide processing on the biosynthesis and function of insulin and insulin-like growth factor-I receptors.

PubMed

Duronio, V; Jacobs, S; Romero, P A; Herscovics, A

1988-04-15

We have used specific inhibitors of oligosaccharide processing enzymes as probes to determine the involvement of oligosaccharide residues in the biosynthesis and function of insulin and insulin-like growth factor-I receptors. In a previous study (Duronio, V., Jacobs, S., and Cuatrecasas, P. (1986) J. Biol. Chem. 261, 970-975) swainsonine was used to inhibit mannosidase II, resulting in the production of receptors containing only hybrid-type oligosaccharides. These receptors had a slightly lower molecular weight and were much more sensitive to endoglycosidase H, but otherwise behaved identically to normal receptors. In this study, we used two compounds that inhibit oligosaccharide processing at earlier steps: (i) N-methyl-1-deoxynojirimycin (MedJN), which inhibits glucosidases I and II and yields glucosylated, high mannose oligosaccharides, and (ii) manno-1-deoxynojirimycin (MandJN), which inhibits mannosidase I and yields high mannose oligosaccharides. In the presence of MandJN, HepG2 cells synthesized receptors of lower molecular weight, which were cleaved into alpha and beta subunits and were able to bind hormone and autophosphorylate. These receptors were as sensitive to endoglycosidase H as receptors made in the presence of swainsonine. In the presence of MedJN, receptors of only slightly lower molecular weight than normal were synthesized and were shown to contain some glucosylated high mannose oligosaccharides. These receptors were able to bind hormone and retained hormone-sensitive autophosphorylation activity. In both cases, the incompletely processed receptors could be detected at the cell surface by cross-linking of iodinated hormone and susceptibility to trypsin digestion, although less receptor was present in cells treated with MedJN. Studies of receptor synthesis using pulse-chase labeling showed that the receptor precursors synthesized in the presence of MedJN were cleaved into alpha and beta subunits at a slower rate than normal receptors or those made in the presence of MandJN. Inhibition of oligosaccharide processing had no effect on the association of the receptor subunits into disulfide-linked oligomeric complexes.

Individual differences in flow proneness are linked to a dopamine D2 receptor gene variant.

PubMed

Gyurkovics, Mate; Kotyuk, Eszter; Katonai, Eniko Rozsa; Horvath, Erzsebet Zsofia; Vereczkei, Andrea; Szekely, Anna

2016-05-01

Flow is a special mental state characterized by deep concentration that occurs during the performance of optimally challenging tasks. In prior studies, proneness to experience flow has been found to be moderately heritable. In the present study, we investigated whether individual differences in flow proneness are related to a polymorphism of the dopamine D2 receptor coding gene (DRD2 C957T rs6277). This polymorphism affects striatal D2 receptor availability, a factor that has been shown to be related to flow proneness. To our knowledge, this is the first study to investigate the association between this trait and a specific gene variant. In a sample of 236 healthy Hungarian adults, we found that CC homozygotes report higher flow proneness than do T allele carriers, but only during mandatory activities (i.e., studying and working), not during leisure time. We discuss implications of this result, e.g., the potential mediators of the relationship. Copyright © 2016 Elsevier Inc. All rights reserved.

The CAG polymorphism in androgen receptor (AR) gene impacts the moral permissibility of harmful behavior in females.

PubMed

Gong, Pingyuan; Fang, Pengpeng; Yang, Xing; Ru, Wenzhao; Wang, Bei; Gao, Xiaocai; Liu, Jinting

2017-06-01

The moral permissibility of harm is strikingly varied among individuals. In light of the connection between testosterone levels and utilitarian moral judgment, this study examined to what extent a CAG polymorphism in the androgen receptor gene, a genetic polymorphism with the ability to regulate testosterone function, contributes to individual differences in moral judgment. Four hundred and thirty-nine Chinese Han participants completed permissibility ratings of harm in moral dilemmas and moral transgression scenarios. Results showed a significant association between the CAG polymorphism and moral permissibility of harm in females. Females with more copies of the S allele, which is associated with higher availability of testosterone, were more likely to judge harmful utilitarian acts and unintentionally harmful acts as permissible, while these effects were absent in males. The findings provide the first evidence for a link between the androgen receptor gene and moral judgment and highlight the role of androgens in moral foundations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ubc13 and COOH Terminus of Hsp70-interacting Protein (CHIP) Are Required for Growth Hormone Receptor Endocytosis*

PubMed Central

Slotman, Johan A.; da Silva Almeida, Ana C.; Hassink, Gerco C.; van de Ven, Robert H. A.; van Kerkhof, Peter; Kuiken, Hendrik J.; Strous, Ger J.

2012-01-01

Growth hormone receptor (GHR) endocytosis is a highly regulated process that depends on the binding and activity of the multimeric ubiquitin ligase, SCFβTrCP (Skp Cullin F-box). Despite a specific interaction between β-transducin repeat-containing protein (βTrCP) and the GHR, and a strict requirement for ubiquitination activity, the receptor is not an obligatory target for SCFβTrCP-directed Lys48 polyubiquitination. We now show that also Lys63-linked ubiquitin chain formation is required for GHR endocytosis. We identified both the ubiquitin-conjugating enzyme Ubc13 and the ubiquitin ligase COOH terminus of Hsp70 interacting protein (CHIP) as being connected to this process. Ubc13 activity and its interaction with CHIP precede endocytosis of GHR. In addition to βTrCP, CHIP interacts specifically with the cytosolic tails of the dimeric GHR, identifying both Ubc13 and CHIP as novel factors in the regulation of cell surface availability of GHR. PMID:22433856

Structural Insights into Cargo Recognition by the Yeast PTS1 Receptor*

PubMed Central

Hagen, Stefanie; Drepper, Friedel; Fischer, Sven; Fodor, Krisztian; Passon, Daniel; Platta, Harald W.; Zenn, Michael; Schliebs, Wolfgang; Girzalsky, Wolfgang; Wilmanns, Matthias; Warscheid, Bettina; Erdmann, Ralf

2015-01-01

The peroxisomal matrix protein import is facilitated by cycling import receptors that shuttle between the cytosol and the peroxisomal membrane. The import receptor Pex5p mediates the import of proteins harboring a peroxisomal targeting signal of type I (PTS1). Purified recombinant Pex5p forms a dimeric complex with the PTS1-protein Pcs60p in vitro with a KD of 0.19 μm. To analyze the structural basis for receptor-cargo recognition, the PTS1 and adjacent amino acids of Pcs60p were systematically scanned for Pex5p binding by an in vitro site-directed photo-cross-linking approach. The cross-linked binding regions of the receptor were subsequently identified by high resolution mass spectrometry. Most cross-links were found with TPR6, TPR7, as well as the 7C-loop of Pex5p. Surface plasmon resonance analysis revealed a bivalent interaction mode for Pex5p and Pcs60p. Interestingly, Pcs60p lacking its C-terminal tripeptide sequence was efficiently cross-linked to the same regions of Pex5p. The KD value of the interaction of truncated Pcs60p and Pex5p was in the range of 7.7 μm. Isothermal titration calorimetry and surface plasmon resonance measurements revealed a monovalent binding mode for the interaction of Pex5p and Pcs60p lacking the PTS1. Our data indicate that Pcs60p contains a second contact site for its receptor Pex5p, beyond the C-terminal tripeptide. The physiological relevance of the ancillary binding region was supported by in vivo import studies. The bivalent binding mode might be explained by a two-step concept as follows: first, cargo recognition and initial tethering by the PTS1-receptor Pex5p; second, lock-in of receptor and cargo. PMID:26359497

The 5-HT7 receptor as a potential target for treating drug and alcohol abuse

PubMed Central

Hauser, Sheketha R.; Hedlund, Peter B.; Roberts, Amanda J.; Sari, Youssef; Bell, Richard L.; Engleman, Eric A.

2015-01-01

Alcohol and drug abuse take a large toll on society and affected individuals. However, very few effective treatments are currently available to treat alcohol and drug addiction. Basic and clinical research has begun to provide some insights into the underlying neurobiological systems involved in the addiction process. Several neurotransmitter pathways have been implicated and distinct reward neurocircuitry have been proposed—including the mesocorticolimbic dopamine (MCL-DA) system and the extended amygdala. The serotonin (5-HT) neurotransmitter system is of particular interest and multiple 5-HT receptors are thought to play significant roles in alcohol and drug self-administration and the development of drug dependence. Among the 5-HT receptors, the 5-HT7 receptor is currently undergoing characterization as a potential target for the treatment of several psychiatric disorders. Although this receptor has received only limited research regarding addictive behaviors, aspects of its neuroanatomical, biochemical, physiological, pharmacological, and behavioral profiles suggest that it could play a key role in the addiction process. For instance, genomic studies in humans have suggested a link between variants in the gene encoding the 5-HT7 receptor and alcoholism. Recent behavioral testing using high-affinity antagonists in mice and preliminary tests with alcohol-preferring rats suggest that this receptor could mediate alcohol consumption and/or reinforcement and play a role in seeking/craving behavior. Interest in the development of new and more selective pharmacological agents for this receptor will aid in examining the 5-HT7 receptor as a novel target for treating addiction. PMID:25628528

The REV-ERBs and RORs: molecular links between circadian rhythms and lipid homeostasis

PubMed Central

Solt, Laura A; Kojetin, Douglas J; Burris, Thomas P

2011-01-01

Research efforts spanning the past two decades have established a clear link between nuclear receptor function, regulation of the circadian clock and lipid homeostasis. As such, this family of receptors represents an important area of research. Recent advances in the field have identified two nuclear receptor subfamilies, the REV-ERBs and the ‘retinoic acid receptor-related orphan receptors’ (RORs), as critical regulators of the circadian clock with significant roles in lipid homeostasis. In this review, the latest information garnered from cutting-edge research on these two nuclear receptor subfamilies will be discussed. Through direct targeting of the REV-ERBs and RORs with synthetic ligands, generation of novel tools aimed at characterizing their function in vivo have been developed, which may lead to novel therapeutics for the treatment of metabolic disorders. PMID:21526899

Microsatellites within the feline androgen receptor are suitable for X chromosome-linked clonality testing in archival material.

PubMed

Farwick, Nadine M; Klopfleisch, Robert; Gruber, Achim D; Weiss, Alexander Th A

2017-04-01

Objectives A hallmark of neoplasms is their origin from a single cell; that is, clonality. Many techniques have been developed in human medicine to utilise this feature of tumours for diagnostic purposes. One approach is X chromosome-linked clonality testing using polymorphisms of genes encoded by genes on the X chromosome. The aim of this study was to determine if the feline androgen receptor gene was suitable for X chromosome-linked clonality testing. Methods The feline androgen receptor gene was characterised and used to test clonality of feline lymphomas by PCR and polyacrylamide gel electrophoresis, using archival formalin-fixed, paraffin-embedded material. Results Clonality of the feline lymphomas under study was confirmed and the gene locus was shown to represent a suitable target in clonality testing. Conclusions and relevance Because there are some pitfalls of using X chromosome-linked clonality testing, further studies are necessary to establish this technique in the cat.

Signaling network of dendritic cells in response to pathogens: a community-input supported knowledgebase.

PubMed

Patil, Sonali; Pincas, Hanna; Seto, Jeremy; Nudelman, German; Nudelman, Irina; Sealfon, Stuart C

2010-10-07

Dendritic cells are antigen-presenting cells that play an essential role in linking the innate and adaptive immune systems. Much research has focused on the signaling pathways triggered upon infection of dendritic cells by various pathogens. The high level of activity in the field makes it desirable to have a pathway-based resource to access the information in the literature. Current pathway diagrams lack either comprehensiveness, or an open-access editorial interface. Hence, there is a need for a dependable, expertly curated knowledgebase that integrates this information into a map of signaling networks. We have built a detailed diagram of the dendritic cell signaling network, with the goal of providing researchers with a valuable resource and a facile method for community input. Network construction has relied on comprehensive review of the literature and regular updates. The diagram includes detailed depictions of pathways activated downstream of different pathogen recognition receptors such as Toll-like receptors, retinoic acid-inducible gene-I-like receptors, C-type lectin receptors and nucleotide-binding oligomerization domain-like receptors. Initially assembled using CellDesigner software, it provides an annotated graphical representation of interactions stored in Systems Biology Mark-up Language. The network, which comprises 249 nodes and 213 edges, has been web-published through the Biological Pathway Publisher software suite. Nodes are annotated with PubMed references and gene-related information, and linked to a public wiki, providing a discussion forum for updates and corrections. To gain more insight into regulatory patterns of dendritic cell signaling, we analyzed the network using graph-theory methods: bifan, feedforward and multi-input convergence motifs were enriched. This emphasis on activating control mechanisms is consonant with a network that subserves persistent and coordinated responses to pathogen detection. This map represents a navigable aid for presenting a consensus view of the current knowledge on dendritic cell signaling that can be continuously improved through contributions of research community experts. Because the map is available in a machine readable format, it can be edited and may assist researchers in data analysis. Furthermore, the availability of a comprehensive knowledgebase might help further research in this area such as vaccine development. The dendritic cell signaling knowledgebase is accessible at http://tsb.mssm.edu/pathwayPublisher/DC_pathway/DC_pathway_index.html.

Enhanced serotonin response in the hippocampus of Galphaz protein knock-out mice.

PubMed

Oleskevich, Sharon; Leck, Kwong-Joo; Matthaei, Klaus; Hendry, Ian A

2005-06-21

The serotonin-1A [5-hydroxytryptamine 1A (5HT1A)] receptor is important for emotional and homeostatic processes in the central nervous system. In the hippocampus, the 5HT1A receptor couples to inhibitory Gi/o proteins to decrease pyramidal cell excitability. Here we investigate the 5HT1A receptor in a mouse deficient in the alpha-subunit of Gz protein (Galphaz knock-out). Behavioural tests showed heightened anxiety and depression-like behaviour in the Galphaz knock-out mice. Whole-cell recording in CA1 pyramidal neurons showed a significantly greater 5HT1A receptor-mediated potassium current in Galphaz knock-out mice. The effect was independent of 5HT4 receptors as the slow after-hyperpolarization was unaffected and a slow depolarization was absent in the Galphaz knock-out mice. Other receptors linked to Gi/o proteins [gamma-aminobutyric acid type B receptor (GABAB), adenosine A1 and muscarinic acetylcholine receptors] were not affected in Galphaz knock-out mice. These results suggest that the 5HT1A receptor may be linked to Galphaz protein, as reported previously in cell culture but shown here in an intact neural network.

Biosynthesis and intracellular transport of the receptor for platelet-derived growth factor.

PubMed Central

Claesson-Welsh, L; Rönnstrand, L; Heldin, C H

1987-01-01

The biosynthesis of the receptor for platelet-derived growth factor (PDGF) was examined in metabolically labeled human foreskin fibroblasts. The receptor was synthesized as a 145-kDa precursor, which, when incubated with endo-beta-N-acetylglucosaminidase H (endo H), underwent a 15-kDa decrease in molecular mass. This indicates that the size of the core protein is about 130 kDa and that the 145-kDa form represents a receptor precursor carrying high-mannose N-linked oligosaccharide groups. Within 15 min after synthesis, the receptor was converted to a 165-kDa form. This form was entirely resistant to endo H treatment and probably represents a receptor molecule that has undergone further posttranslational modification, including O-linked glycosylation. Subsequently, within 30 min, a molecule of 170 kDa--i.e., the size of the mature receptor--appeared. A slightly larger molecule, of 175 kDa, which could be immunoprecipitated from PDGF-stimulated 32P-labeled cells, probably represents a receptor further modified by autophosphorylation. The 170-kDa molecule had an isoelectric point of about 4.5. Addition of PDGF increased the turnover rate of the 170-kDa PDGF receptor. Images PMID:2827155

Translational Evidence for a Role of Endocannabinoids in the Etiology and Treatment of Posttraumatic Stress Disorder

PubMed Central

Neumeister, Alexander; Seidel, Jordan; Ragen, Benjamin J.; Pietrzak, Robert H.

2014-01-01

Introduction Posttraumatic stress disorder (PTSD) is a prevalent, chronic, and disabling anxiety disorder that may develop following exposure to a traumatic event. Despite the public health significance of PTSD, relatively little is known about the etiology or pathophysiology of this disorder, and pharmacotherapy development to date has been largely opportunistic instead of mechanism-based. Recently, an accumulating body of evidence has implicated the endocannabinoid system in the etiology of PTSD, and targets within this system are believed to be suitable for treatment development. Methods Herein, we describe evidence from translational studies arguing for the relevance of the endocannabinoid system in the etiology of PTSD. We also show mechanisms relevant for treatment development. Results There is convincing evidence from multiple studies for reduced endocannabinoid availability in PTSD. Brain imaging studies show molecular adaptations with elevated cannabinoid type 1 (CB1) receptor availability in PTSD which is linked to abnormal threat processing and anxious arousal symptoms. Conclusion Of particular relevance is evidence showing reduced levels of the endocannabinoid anandamide and compensatory increase of CB1 receptor availability in PTSD, and an association between increased CB1 receptor availability in the amygdala and abnormal threat processing, as well as increased severity of hyperarousal, but not dysphoric symptomatology, in trauma survivors. Given that hyperarousal symptoms are the key drivers of more disabling aspects of PTSD such as emotional numbing or suicidality, novel, mechanism-based pharmacotherapies that target this particular symptom cluster in patients with PTSD may have utility in mitigating the chronicity and morbidity of the disorder. PMID:25456347

Translational evidence for a role of endocannabinoids in the etiology and treatment of posttraumatic stress disorder.

PubMed

Neumeister, Alexander; Seidel, Jordan; Ragen, Benjamin J; Pietrzak, Robert H

2015-01-01

Posttraumatic stress disorder (PTSD) is a prevalent, chronic, and disabling anxiety disorder that may develop following exposure to a traumatic event. Despite the public health significance of PTSD, relatively little is known about the etiology or pathophysiology of this disorder, and pharmacotherapy development to date has been largely opportunistic instead of mechanism-based. Recently, an accumulating body of evidence has implicated the endocannabinoid system in the etiology of PTSD, and targets within this system are believed to be suitable for treatment development. Herein, we describe evidence from translational studies arguing for the relevance of the endocannabinoid system in the etiology of PTSD. We also show mechanisms relevant for treatment development. There is convincing evidence from multiple studies for reduced endocannabinoid availability in PTSD. Brain imaging studies show molecular adaptations with elevated cannabinoid type 1 (CB1) receptor availability in PTSD which is linked to abnormal threat processing and anxious arousal symptoms. Of particular relevance is evidence showing reduced levels of the endocannabinoid anandamide and compensatory increase of CB1 receptor availability in PTSD, and an association between increased CB1 receptor availability in the amygdala and abnormal threat processing, as well as increased severity of hyperarousal, but not dysphoric symptomatology, in trauma survivors. Given that hyperarousal symptoms are the key drivers of more disabling aspects of PTSD such as emotional numbing or suicidality, novel, mechanism-based pharmacotherapies that target this particular symptom cluster in patients with PTSD may have utility in mitigating the chronicity and morbidity of the disorder. Copyright © 2014 Elsevier Ltd. All rights reserved.

General Linker Diversification Approach to Bivalent Ligand Assembly: Generation of an Array of Ligands for the Cation-Independent Mannose 6-Phosphate Receptor.

PubMed

Fei, Xiang; Zavorka, Megan E; Malik, Guillaume; Connelly, Christopher M; MacDonald, Richard G; Berkowitz, David B

2017-08-18

A generalized strategy is presented for the rapid assembly of a set of bivalent ligands with a variety of linking functionalities from a common monomer. Herein, an array of phosphatase-inert mannose-6-phosphonate-presenting ligands for the cation-independent-mannose 6-phosphate receptor (CI-MPR) is constructed. Receptor binding affinity varies with linking functionality-the simple amide and 1,5-triazole(tetrazole) being preferred over the 1,4-triazole. This approach is expected to find application across chemical biology, particularly in glycoscience, wherein multivalency often governs molecular recognition.

Ionotropic GABA and Glutamate Receptor Mutations and Human Neurologic Diseases.

PubMed

Yuan, Hongjie; Low, Chian-Ming; Moody, Olivia A; Jenkins, Andrew; Traynelis, Stephen F

2015-07-01

The advent of whole exome/genome sequencing and the technology-driven reduction in the cost of next-generation sequencing as well as the introduction of diagnostic-targeted sequencing chips have resulted in an unprecedented volume of data directly linking patient genomic variability to disorders of the brain. This information has the potential to transform our understanding of neurologic disorders by improving diagnoses, illuminating the molecular heterogeneity underlying diseases, and identifying new targets for therapeutic treatment. There is a strong history of mutations in GABA receptor genes being involved in neurologic diseases, particularly the epilepsies. In addition, a substantial number of variants and mutations have been found in GABA receptor genes in patients with autism, schizophrenia, and addiction, suggesting potential links between the GABA receptors and these conditions. A new and unexpected outcome from sequencing efforts has been the surprising number of mutations found in glutamate receptor subunits, with the GRIN2A gene encoding the GluN2A N-methyl-d-aspartate receptor subunit being most often affected. These mutations are associated with multiple neurologic conditions, for which seizure disorders comprise the largest group. The GluN2A subunit appears to be a locus for epilepsy, which holds important therapeutic implications. Virtually all α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor mutations, most of which occur within GRIA3, are from patients with intellectual disabilities, suggesting a link to this condition. Similarly, the most common phenotype for kainate receptor variants is intellectual disability. Herein, we summarize the current understanding of disease-associated mutations in ionotropic GABA and glutamate receptor families, and discuss implications regarding the identification of human mutations and treatment of neurologic diseases. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Ionotropic GABA and Glutamate Receptor Mutations and Human Neurologic Diseases

PubMed Central

Yuan, Hongjie; Low, Chian-Ming; Moody, Olivia A.; Jenkins, Andrew

2015-01-01

The advent of whole exome/genome sequencing and the technology-driven reduction in the cost of next-generation sequencing as well as the introduction of diagnostic-targeted sequencing chips have resulted in an unprecedented volume of data directly linking patient genomic variability to disorders of the brain. This information has the potential to transform our understanding of neurologic disorders by improving diagnoses, illuminating the molecular heterogeneity underlying diseases, and identifying new targets for therapeutic treatment. There is a strong history of mutations in GABA receptor genes being involved in neurologic diseases, particularly the epilepsies. In addition, a substantial number of variants and mutations have been found in GABA receptor genes in patients with autism, schizophrenia, and addiction, suggesting potential links between the GABA receptors and these conditions. A new and unexpected outcome from sequencing efforts has been the surprising number of mutations found in glutamate receptor subunits, with the GRIN2A gene encoding the GluN2A N-methyl-d-aspartate receptor subunit being most often affected. These mutations are associated with multiple neurologic conditions, for which seizure disorders comprise the largest group. The GluN2A subunit appears to be a locus for epilepsy, which holds important therapeutic implications. Virtually all α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor mutations, most of which occur within GRIA3, are from patients with intellectual disabilities, suggesting a link to this condition. Similarly, the most common phenotype for kainate receptor variants is intellectual disability. Herein, we summarize the current understanding of disease-associated mutations in ionotropic GABA and glutamate receptor families, and discuss implications regarding the identification of human mutations and treatment of neurologic diseases. PMID:25904555

Taking on breast cancer in East Africa: global challenges in breast cancer.

PubMed

Kantelhardt, Eva Johanna; Cubasch, Herbert; Hanson, Claudia

2015-02-01

To provide an update on breast cancer epidemiology, early detection, and therapy in Africa. Breast cancer has been a long neglected topic in Africa. Due to increased activities of population-based cancer registries, cancer incidence rates become available. Data from 26 African countries for 2012 suggest that in the majority of countries, breast cancer has turned into the leading cancer among the female population. Yet data from hospital-based registries show that patients often present late. Efforts are being made to implement early detection programs; however, there are open questions how best to organize screening activities, referral and how to assure pathology service. Adjuvant treatment is still limited to a small number of centers; neoadjuvant treatment is underutilized. New data have become available from different countries reporting high proportions of estrogen receptor-positive tumors, which would possibly justify the administration of tamoxifen in unknown receptor status. Breast cancer is an increasing health problem in low-resource countries. More information on incidence, clinical presentation, outcome, and tumor biology in Africa has become available. Further evidence is needed on strategies to improve awareness, appropriate treatment options, and implementation of palliative care. http://links.lww.com/COOG/A17

Striatal dopamine D2/3 receptor regulation by stress inoculation in squirrel monkeys.

PubMed

Lee, Alex G; Nechvatal, Jordan M; Shen, Bin; Buckmaster, Christine L; Levy, Michael J; Chin, Frederick T; Schatzberg, Alan F; Lyons, David M

2016-06-01

Intermittent mildly stressful situations provide opportunities to learn, practice, and improve coping in a process called stress inoculation. Stress inoculation also enhances cognitive control and response inhibition of impulsive motivated behavior. Cognitive control and motivation have been linked to striatal dopamine D2 and/or D3 receptors (DRD2/3) in rodents, monkeys, and humans. Here, we study squirrel monkeys randomized early in life to stress inoculation with or without maternal companionship and a no-stress control treatment condition. Striatal DRD2/3 availability in adulthood was measured in vivo by [ 11 C]raclopride binding using positron emission tomography (PET). DRD2/3 availability was greater in caudate and putamen compared to ventral striatum as reported in PET studies of humans and other non-human primates. DRD2/3 availability in ventral striatum was also consistently greater in stress inoculated squirrel monkeys compared to no-stress controls. Squirrel monkeys exposed to stress inoculation in the presence of their mother did not differ from squirrel monkeys exposed to stress inoculation without maternal companionship. Similar effects in different social contexts extend the generality of our findings and together suggest that stress inoculation increases striatal DRD2/3 availability as a correlate of cognitive control in squirrel monkeys.

Experimental treatment of antipsychotic-induced movement disorders

PubMed Central

Shireen, Erum

2016-01-01

Antipsychotic drugs are extensively prescribed for the treatment of schizophrenia and other related psychiatric disorders. These drugs produced their action by blocking dopamine (DA) receptors, and these receptors are widely present throughout the brain. Therefore, extended antipsychotic use also leads to severe extrapyramidal side effects. The short-term effects include parkinsonism and the later appearing tardive dyskinesia. Currently available treatments for these disorders are mostly symptomatic and insufficient, and are often linked with a number of detrimental side effects. Antipsychotic-drug-induced tardive dyskinesia prompted researchers to explore novel drugs with fewer undesirable extrapyramidal side effects. Preclinical studies suggest a role of 5-hydroxytryptamine (serotonin)-1A and 2A/2C receptors in the modulation of dopaminergic neurotransmission and motivating a search for better therapeutic strategies for schizophrenia and related disorders. In addition, adjunctive treatment with antioxidants such as vitamin E, red rice bran oil, and curcumin in the early phases of illness may prevent additional oxidative injury, and thus improve and prevent further possible worsening of related neurological and behavioral deficits in schizophrenia. This review explains the role of serotonergic receptors and oxidative stress, with the aim of providing principles for prospect development of compounds to improve therapeutic effects of antischizophrenic drugs. PMID:27540314

Structural basis of G protein-coupled receptor-Gi protein interaction: formation of the cannabinoid CB2 receptor-Gi protein complex.

PubMed

Mnpotra, Jagjeet S; Qiao, Zhuanhong; Cai, Jian; Lynch, Diane L; Grossfield, Alan; Leioatts, Nicholas; Hurst, Dow P; Pitman, Michael C; Song, Zhao-Hui; Reggio, Patricia H

2014-07-18

In this study, we applied a comprehensive G protein-coupled receptor-Gαi protein chemical cross-linking strategy to map the cannabinoid receptor subtype 2 (CB2)-Gαi interface and then used molecular dynamics simulations to explore the dynamics of complex formation. Three cross-link sites were identified using LC-MS/MS and electrospray ionization-MS/MS as follows: 1) a sulfhydryl cross-link between C3.53(134) in TMH3 and the Gαi C-terminal i-3 residue Cys-351; 2) a lysine cross-link between K6.35(245) in TMH6 and the Gαi C-terminal i-5 residue, Lys-349; and 3) a lysine cross-link between K5.64(215) in TMH5 and the Gαi α4β6 loop residue, Lys-317. To investigate the dynamics and nature of the conformational changes involved in CB2·Gi complex formation, we carried out microsecond-time scale molecular dynamics simulations of the CB2 R*·Gαi1β1γ2 complex embedded in a 1-palmitoyl-2-oleoyl-phosphatidylcholine bilayer, using cross-linking information as validation. Our results show that although molecular dynamics simulations started with the G protein orientation in the β2-AR*·Gαsβ1γ2 complex crystal structure, the Gαi1β1γ2 protein reoriented itself within 300 ns. Two major changes occurred as follows. 1) The Gαi1 α5 helix tilt changed due to the outward movement of TMH5 in CB2 R*. 2) A 25° clockwise rotation of Gαi1β1γ2 underneath CB2 R* occurred, with rotation ceasing when Pro-139 (IC-2 loop) anchors in a hydrophobic pocket on Gαi1 (Val-34, Leu-194, Phe-196, Phe-336, Thr-340, Ile-343, and Ile-344). In this complex, all three experimentally identified cross-links can occur. These findings should be relevant for other class A G protein-coupled receptors that couple to Gi proteins. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Subcortical intelligence: caudate volume predicts IQ in healthy adults.

PubMed

Grazioplene, Rachael G; G Ryman, Sephira; Gray, Jeremy R; Rustichini, Aldo; Jung, Rex E; DeYoung, Colin G

2015-04-01

This study examined the association between size of the caudate nuclei and intelligence. Based on the central role of the caudate in learning, as well as neuroimaging studies linking greater caudate volume to better attentional function, verbal ability, and dopamine receptor availability, we hypothesized the existence of a positive association between intelligence and caudate volume in three large independent samples of healthy adults (total N = 517). Regression of IQ onto bilateral caudate volume controlling for age, sex, and total brain volume indicated a significant positive correlation between caudate volume and intelligence, with a comparable magnitude of effect across each of the three samples. No other subcortical structures were independently associated with IQ, suggesting a specific biological link between caudate morphology and intelligence. © 2014 Wiley Periodicals, Inc.

A positive relationship between harm avoidance and brain nicotinic acetylcholine receptor availability.

PubMed

Storage, Steven; Mandelkern, Mark A; Phuong, Jonathan; Kozman, Maggie; Neary, Meaghan K; Brody, Arthur L

2013-12-30

Prior research indicates that disturbance of cholinergic neurotransmission reduces anxiety, leading to the hypothesis that people with heightened cholinergic function have a greater tendency toward anxiety-like and/or harm-avoidant behavior. We sought to determine if people with elevated levels of harm avoidance (HA), a dimension of temperament from the Temperament and Character Inventory (TCI), have high α4β2* nicotinic acetylcholine receptor (nAChR) availability. Healthy adults (n=105; 47 non-smokers and 58 smokers) underwent bolus-plus-continuous infusion positron emission tomography (PET) scanning using the radiotracer 2-[18F]fluoro-3-(2(S)azetidinylmethoxy) pyridine (abbreviated as 2-FA). During the uptake period of 2-FA, participants completed the TCI. The central study analysis revealed a significant association between total HA and mean nAChR availability, with higher total HA scores being linked with greater nAChR availability. In examining HA subscales, both 'Fear of Uncertainty' and 'Fatigability' were significant, based on higher levels of these characteristics being associated with greater nAChR availabilities. This study adds to a growing body of knowledge concerning the biological basis of personality and may prove useful in understanding the pathophysiology of psychiatric disorders (such as anxiety disorders) that have similar characteristics to HA. Study findings may indicate that heightened cholinergic neurotransmission is associated with increased anxiety-like traits. Published by Elsevier Ireland Ltd.

A positive relationship between harm avoidance and brain nicotinic acetylcholine receptor availability

PubMed Central

Storage, Steven; Mandelkern, Mark A.; Phuong, Jonathan; Kozman, Maggie; Neary, Meaghan K.; Brody, Arthur L.

2013-01-01

Prior research indicates that disturbance of cholinergic neurotransmission reduces anxiety, leading to the hypothesis that people with heightened cholinergic function have a greater tendency toward anxiety-like and/or harm-avoidant behavior. We sought to determine if people with elevated levels of harm avoidance (HA), a dimension of temperament from the Temperament and Character Inventory (TCI), have high α4β2* nicotinic acetylcholine receptor (nAChR) availability. Healthy adults (n = 105; 47 non-smokers and 58 smokers) underwent bolus-plus-continuous infusion positron emission tomography (PET) scanning using the radiotracer 2-[18F]fluoro-3-(2(S)azetidinylmethoxy) pyridine (abbreviated as 2-FA). During the uptake period of 2-FA, participants completed the TCI. The central study analysis revealed a significant association between total HA and mean nAChR availability, with higher total HA scores being linked with greater nAChR availability. In examining HA subscales, both ‘Fear of Uncertainty’ and ‘Fatigability’ were significant, based on higher levels of these characteristics being associated with greater nAChR availabilities. This study adds to a growing body of knowledge concerning the biological basis of personality and may prove useful in understanding the pathophysiology of psychiatric disorders (such as anxiety disorders) that have similar characteristics to HA. Study findings may indicate that heightened cholinergic neurotransmission is associated with increased anxiety-like traits. PMID:24148908

Synthesis and receptor binding studies of (+/-)1-iodo-MK-801

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

Yang, D.J.; Ciliax, B.J.; Van Dort, M.E.

1989-06-01

The glutamate analogue N-methyl-D-aspartate (NMDA) binds to a subset of glutamate receptors that are coupled to a voltage-sensitive cation channel. This NMDA-linked channel is the likely binding locus of the potent anticonvulsant MK-801. To develop single-photon emission computed tomography (SPECT) probes of this brain channel, we synthesized (+/)1-iodo-MK-801 and (+/-)1-({sup 125}I)iodo-MK-801. The effect of (+/-)1-iodo-MK-801 on ligand binding to the NMDA-linked glutamate receptor site was assessed using a rat brain homogenate assay. (+/-)1-Iodo-MK-801 displaced the dissociative anesthetic ligand ({sup 3}H)N-(1-(2-thienyl)cyclohexyl)piperidine (({sup 3}H)TCP) binding with an IC50 of 1 microM, which is a 10-fold lower binding affinity than that of (+/-)MK-801.more » In in vivo autoradiographic studies, (+/-)MK-801 failed to block selective uptake of (+/-)1-iodo-MK-801 in rat brain. These results suggest that (+/-)1-iodo-MK-801 may not be a suitable ligand for mapping NMDA-linked glutamate receptor channels.« less

Hmrbase: a database of hormones and their receptors

PubMed Central

Rashid, Mamoon; Singla, Deepak; Sharma, Arun; Kumar, Manish; Raghava, Gajendra PS

2009-01-01

Background Hormones are signaling molecules that play vital roles in various life processes, like growth and differentiation, physiology, and reproduction. These molecules are mostly secreted by endocrine glands, and transported to target organs through the bloodstream. Deficient, or excessive, levels of hormones are associated with several diseases such as cancer, osteoporosis, diabetes etc. Thus, it is important to collect and compile information about hormones and their receptors. Description This manuscript describes a database called Hmrbase which has been developed for managing information about hormones and their receptors. It is a highly curated database for which information has been collected from the literature and the public databases. The current version of Hmrbase contains comprehensive information about ~2000 hormones, e.g., about their function, source organism, receptors, mature sequences, structures etc. Hmrbase also contains information about ~3000 hormone receptors, in terms of amino acid sequences, subcellular localizations, ligands, and post-translational modifications etc. One of the major features of this database is that it provides data about ~4100 hormone-receptor pairs. A number of online tools have been integrated into the database, to provide the facilities like keyword search, structure-based search, mapping of a given peptide(s) on the hormone/receptor sequence, sequence similarity search. This database also provides a number of external links to other resources/databases in order to help in the retrieving of further related information. Conclusion Owing to the high impact of endocrine research in the biomedical sciences, the Hmrbase could become a leading data portal for researchers. The salient features of Hmrbase are hormone-receptor pair-related information, mapping of peptide stretches on the protein sequences of hormones and receptors, Pfam domain annotations, categorical browsing options, online data submission, DrugPedia linkage etc. Hmrbase is available online for public from . PMID:19589147

PEROXISOME-PROLIFERATOR ACTIVATED RECEPTORS AS A MACROMOLECULAR TARGET FOR CHEMICAL TOXICITY: MODELS OF THE INTERACTIONS OF PPARS WITH PERFLUORINATED ORGANIC COMPOUNDS.

EPA Science Inventory

The Peroxisome Proliferator Activated Receptors (PPARs), a class of nuclear receptors that modulate both transcription and metabolic processes, are implicated in a variety of metabolic disorders linked to lipidogenesis, adipose tissue accumulation, fatty-acid oxidation pathways, ...

β2-Adrenergic Receptor Knockout Mice Exhibit A Diabetic Retinopathy Phenotype

PubMed Central

Jiang, Youde; Zhang, Qiuhua; Liu, Li; Tang, Jie; Kern, Timothy S.; Steinle, Jena J.

2013-01-01

There is considerable evidence from our lab and others for a functional link between β-adrenergic receptor and insulin receptor signaling pathways in retina. Furthermore, we hypothesize that this link may contribute to lesions similar to diabetic retinopathy in that the loss of adrenergic input observed in diabetic retinopathy may disrupt normal anti-apoptotic insulin signaling, leading to retinal cell death. Our studies included assessment of neural retina function (ERG), vascular degeneration, and Müller glial cells (which express only β1 and β2-adrenergic receptor subtypes). In the current study, we produced β2-adrenergic receptor knockout mice to examine this deletion on retinal neurons and vasculature, and to identify specific pathways through which β2-adrenergic receptor modulates insulin signaling. As predicted from our hypothesis, β2-adrenergic receptor knockout mice display certain features similar to diabetic retinopathy. In addition, loss of β2-adrenergic input resulted in an increase in TNFα, a key inhibitor of insulin receptor signaling. Increased TNFα may be associated with insulin-dependent production of the anti-apoptotic factor, Akt. Since the effects occurred in vivo under normal glucose conditions, we postulate that aspects of the diabetic retinopathy phenotype might be triggered by loss of β2-adrenergic receptor signaling. PMID:23894672

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

PubMed Central

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. PMID:29740322

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

PubMed

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.

IGF-1-dependent subunit communication of the IGF-1 holoreceptor: Interactions between. alpha. beta. heterodimeric receptor halves

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

Wilden, P.A.; Treadway, J.L.; Morrison, B.D.

1989-12-12

Examination of {sup 125}I-IGF-1 affinity cross-linking and {beta}-subunit autophosphorylation has indicated that IGF-1 induces a covalent association of isolated {alpha}{beta} heterodimeric IGF-1 receptors into an {alpha}{sub 2}{beta}{sub 2} heterotetrameric state, in a similar manner to that observed for the insulin receptor. The formation of the {alpha}{sub 2}{beta}{sub 2} heterotetrameric IGF-1 receptor complex from the partially purified {alpha}{beta} heterodimers was time dependent with half-maximal formation in approximately 30 min at saturating IGF-1 concentrations. The IGF-1-dependent association of the partially purified {alpha}{beta} heterodimers into an {alpha}{sub 2}{beta}{sub 2} heterotetrameric state was specific for the IGF-1 receptors since IGF-1 was unable to stimulatemore » the protein kinase activity of the purified {alpha}{beta} heterodimeric insulin receptor complex. Incubation of the {alpha}{sub 2}{beta}{sub 2} heterotetrameric IGF-1 holoreceptor with the specific sulfhydryl agent iodoacetamide (IAN) did not alter {sup 125}I-IGF-1 binding or IGF-1 stimulation of protein kinase activity. However, IAN treatment of the {alpha}{beta} heterodimeric IGF-1 receptors inhibited the IGF-1 dependent covalent formation of the disulfide-linked {alpha}{sub 2}{beta}{sub 2} heterotetrameric complex. These data indicate that IGF-1 induces the covalent association of isolated {alpha}{beta} heterodimeric IGF-1 receptor complexes into a disulfide-linked {alpha}{sub 2}{beta}{sub 2} heterotetrameric state whereas Mn/MgATP induces a noncovalent association. Therefore, unlike the insulin receptor in which noncovalent association is sufficient for kinase activation, only the covalent assembly of the IGF-1 receptor {alpha}{beta} heterodimers into the {alpha}{sub 2}{beta}{sub 2} heterotetrameric holoreceptor complex is associated with ligand-stimulated protein kinase activation.« less

Possible roles for products of polymorphic MHC and linked olfactory receptor genes during selection processes in reproduction.

PubMed

Ziegler, Andreas; Dohr, Gotrfried; Uchanska-Ziegler, Barbara

2002-07-01

Polymorphic genes of the human major histocompatibility complex [MHC; human leukocyte antigen (HLA)] are probably important in determining resistance to parasites and avoidance of inbreeding. We investigated whether HLA-associated sexual selection could also involve HLA-linked olfactory receptor (OR) genes, which might not only participate in olfaction-guided mate choice, but also in selection processes within the testis. The testicular expression status of HLA class I molecules (by immunohistology) and HLA-linked OR genes (by transcriptional analysis) was determined. Various HLA class I heavy chains, but not beta2-microglobulin (beta2m), were expressed, mainly at the spermatocyte I stage. Of 17 HLA-linked OR genes analyzed, eight were found to be transcribed in the testis. They exhibited varying numbers of 5'- or 3'-non-coding exons as well as differential splicing. We suggest that testis-expressed polymorphic HLA and OR proteins are functionally connected and serve the selection of spermatozoa, enabling them to distinguish 'self from 'non-self [the sperm-receptor-selection (SRS) hypothesis].

Protein A Suppresses Immune Responses during Staphylococcus aureus Bloodstream Infection in Guinea Pigs

PubMed Central

Kim, Hwan Keun; Falugi, Fabiana; Thomer, Lena; Missiakas, Dominique M.

2015-01-01

ABSTRACT   Staphylococcus aureus infection is not associated with the development of protective immunity, and disease relapses occur frequently. We hypothesize that protein A, a factor that binds immunoglobulin Fcγ and cross-links VH3 clan B cell receptors (IgM), is the staphylococcal determinant for host immune suppression. To test this, vertebrate IgM was examined for protein A cross-linking. High VH3 binding activity occurred with human and guinea immunoglobulin, whereas mouse and rabbit immunoglobulins displayed little and no binding, respectively. Establishing a guinea pig model of S. aureus bloodstream infection, we show that protein A functions as a virulence determinant and suppresses host B cell responses. Immunization with SpAKKAA, which cannot bind immunoglobulin, elicits neutralizing antibodies that enable guinea pigs to develop protective immunity. Importance  Staphylococcus aureus is the leading cause of soft tissue and bloodstream infections; however, a vaccine with clinical efficacy is not available. Using mice to model staphylococcal infection, earlier work identified protective antigens; however, corresponding human clinical trials did not reach their endpoints. We show that B cell receptor (IgM) cross-linking by protein A is an important immune evasion strategy of S. aureus that can be monitored in a guinea pig model of bloodstream infection. Further, immunization with nontoxigenic protein A enables infected guinea pigs to elicit antibody responses that are protective against S. aureus. Thus, the guinea pig model may support preclinical development of staphylococcal vaccines. PMID:25564466

Zein nanoparticles as delivery systems for covalently linked and physically entrapped folic acid

NASA Astrophysics Data System (ADS)

Chuacharoen, Thanida; Sabliov, Cristina M.

2017-02-01

Zein nanoparticles covalently linked to folic acid were hypothesized to sustain the release of the folic acid in addition to targeting cancer cells overexpressing folate-binding receptors, whereas zein nanoparticles with physically entrapped folic acid would only be able to control the release of the bioactive without targeting of cancer cells. The two types of particles, folic acid covalently linked zein nanoparticles (ZN-FA nps) and zein nanoparticles with entrapped folic acid (ZN(FA) nps), were synthesized and the covalent link between folic acid and zein was assessed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR). Their size, polydispersity index, zeta potential, morphology, and loading capacity were evaluated by dynamic light scattering (DLS), transmission electron microscopy (TEM), and spectrophotometric technique. The release studies of the folic acid preformed in phosphate-buffered saline (PBS) at 37 °C for 7 days concluded that the release of the loaded folic acid was sustained over 7 days for both systems. The cytotoxicity was investigated using a methyl thiazolyl tetrazolium (MTT) assay, and the results showed that zein nanoparticles were biocompatible to HeLa (an overexpressing folate receptor cells) and A549 (a deficient folate receptor cells) cells, which have different levels of folate receptors on surface and both folic acid nanoparticle systems were able to diminish the adverse toxic effect of folic acid to cells. The increased uptake of ZN-FA nps relative to ZN(FA) nps supported the use of ZN-FA nps as targeting nanoagents to cells overexpressing folate receptors.

Comprehensive Analysis of Non-Synonymous Natural Variants of G Protein-Coupled Receptors.

PubMed

Kim, Hee Ryung; Duc, Nguyen Minh; Chung, Ka Young

2018-03-01

G protein-coupled receptors (GPCRs) are the largest superfamily of transmembrane receptors and have vital signaling functions in various organs. Because of their critical roles in physiology and pathology, GPCRs are the most commonly used therapeutic target. It has been suggested that GPCRs undergo massive genetic variations such as genetic polymorphisms and DNA insertions or deletions. Among these genetic variations, non-synonymous natural variations change the amino acid sequence and could thus alter GPCR functions such as expression, localization, signaling, and ligand binding, which may be involved in disease development and altered responses to GPCR-targeting drugs. Despite the clinical importance of GPCRs, studies on the genotype-phenotype relationship of GPCR natural variants have been limited to a few GPCRs such as β-adrenergic receptors and opioid receptors. Comprehensive understanding of non-synonymous natural variations within GPCRs would help to predict the unknown genotype-phenotype relationship and yet-to-be-discovered natural variants. Here, we analyzed the non-synonymous natural variants of all non-olfactory GPCRs available from a public database, UniProt. The results suggest that non-synonymous natural variations occur extensively within the GPCR superfamily especially in the N-terminus and transmembrane domains. Within the transmembrane domains, natural variations observed more frequently in the conserved residues, which leads to disruption of the receptor function. Our analysis also suggests that only few non-synonymous natural variations have been studied in efforts to link the variations with functional consequences.

Alpha-1A Adrenergic receptor activation increases inhibitory tone in CA1 hippocampus

PubMed Central

Hillman, Kristin L.; Lei, Saobo; Doze, Van A.

2009-01-01

The endogenous catecholamine norepinephrine (NE) exhibits anti-epileptic properties, however it is not well understood which adrenergic receptor (AR) mediates this effect. The aim of this study was to investigate α1-adrenergic receptor (AR) activation in region CA1 of the hippocampus, a subcortical structure often implicated in temporal lobe epilepsies. Using cell-attached and whole-cell recordings in rat hippocampal slices, we confirmed that selective α1-AR activation increases action potential firing in a subpopulation of CA1 interneurons. We found that this response is mediated via the α1A-AR subtype, initiated by sodium influx, and appears independent of second messenger signaling. In CA1 pyramidal cells, α1A-AR activation decreases activity due to increased pre-synaptic GABA and somatostatin release. Examination of post-synaptic receptor involvement revealed that while GABAA receptors mediate the majority of α1A-adrenergic effects on CA1 pyramidal cells, significant contributions are also made by GABAB and somatostatin receptors. Finally, to test whether α1A-AR activation could have potential therapeutic implications, we performed AR agonist challenges using two in vitro epileptiform models. When GABAA receptors were available, α1A-AR activation significantly decreased epileptiform bursting in CA1. Together, our findings directly link stimulation of the α1A-AR subtype to release of GABA and somatostatin at the single cell level and suggest that α1A-AR activation may represent one mechanism by which NE exerts anti-epileptic effects within the hippocampus. PMID:19201164

Epigenetics in breast and prostate cancer.

PubMed

Wu, Yanyuan; Sarkissyan, Marianna; Vadgama, Jaydutt V

2015-01-01

Most recent investigations into cancer etiology have identified a key role played by epigenetics. Specifically, aberrant DNA and histone modifications which silence tumor suppressor genes or promote oncogenes have been demonstrated in multiple cancer models. While the role of epigenetics in several solid tumor cancers such as colorectal cancer are well established, there is emerging evidence that epigenetics also plays a critical role in breast and prostate cancer. In breast cancer, DNA methylation profiles have been linked to hormone receptor status and tumor progression. Similarly in prostate cancer, epigenetic patterns have been associated with androgen receptor status and response to therapy. The regulation of key receptor pathways and activities which affect clinical therapy treatment options by epigenetics renders this field high priority for elucidating mechanisms and potential targets. A new set of methylation arrays are now available to screen epigenetic changes and provide the cutting-edge tools needed to perform such investigations. The role of nutritional interventions affecting epigenetic changes particularly holds promise. Ultimately, determining the causes and outcomes from epigenetic changes will inform translational applications for utilization as biomarkers for risk and prognosis as well as candidates for therapy.

Nonviral RNA transfection to transiently modify T cells with chimeric antigen receptors for adoptive therapy.

PubMed

Riet, Tobias; Holzinger, Astrid; Dörrie, Jan; Schaft, Niels; Schuler, Gerold; Abken, Hinrich

2013-01-01

Redirecting T cells with a chimeric antigen receptor (CAR) of predefined specificity showed remarkable efficacy in the adoptive therapy trials of malignant diseases. The CAR consists of a single chain fragment of variable region (scFv) antibody targeting domain covalently linked to the CD3ζ signalling domain of the T cell receptor complex to mediate T cell activation upon antigen engagement. By using an antibody-derived targeting domain a CAR can potentially redirect T cells towards any target expressed on the cell surface as long as a binding domain is available. Antibody-mediated targeting moreover circumvents MHC restriction of the targeted antigen, thereby broadening the potential of applicability of adoptive T cell therapy. While T cells were so far genetically modified by viral transduction, transient modification with a CAR by RNA transfection gained increasing interest during the last years. This chapter focuses on methods to modify human T cells from peripheral blood with a CAR by electroporation of in vitro transcribed RNA and to test modified T cells for function for use in adoptive immunotherapy.

Epigenetics in Breast and Prostate Cancer

PubMed Central

Wu, Yanyuan; Sarkissyan, Marianna; Vadgama, Jaydutt V.

2015-01-01

SUMMARY Most recent investigations into cancer etiology have identified a key role played by epigenetics. Specifically, aberrant DNA and histone modifications which silence tumor suppressor genes or promote oncogenes have been demonstrated in multiple cancer models. While the role of epigenetics in several solid tumor cancers such as colorectal cancer are well established, there is emerging evidence that epigenetics also plays a critical role in breast and prostate cancer. In breast cancer, DNA methylation profiles have been linked to hormone receptor status and tumor progression. Similarly in prostate cancer, epigenetic patterns have been associated with androgen receptor status and response to therapy. The regulation of key receptor pathways and activities which affect clinical therapy treatment options by epigenetics renders this field high priority for elucidating mechanisms and potential targets. A new set of methylation arrays are now available to screen epigenetic changes and provide the cuttingedge tools needed to perform such investigations. The role of nutritional interventions affecting epigenetic changes particularly holds promise. Ultimately, determining the causes and outcomes from epigenetic changes will inform translational applications for utilization as biomarkers for risk and prognosis as well as candidates for therapy. PMID:25421674

The Concise Guide to Pharmacology 2013/14: Enzymes

PubMed Central

Alexander, Stephen PH; Benson, Helen E; Faccenda, Elena; Pawson, Adam J; Sharman, Joanna L; Spedding, Michael; Peters, John A; Harmar, Anthony J

2013-01-01

The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Enzymes are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, nuclear hormone receptors, catalytic receptors and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates. PMID:24528243

The Concise Guide to Pharmacology 2013/14: Transporters

PubMed Central

Alexander, Stephen PH; Benson, Helen E; Faccenda, Elena; Pawson, Adam J; Sharman, Joanna L; Spedding, Michael; Peters, John A; Harmar, Anthony J

2013-01-01

The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Transporters are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates. PMID:24528242

Functional somatostatin receptors on a rat pancreatic acinar cell line

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

Viguerie, N.; Tahiri-Jouti, N.; Esteve, J.P.

1988-07-01

Somatostatin receptors from a rat pancreatic acinar cell line, AR4-2J, were characterized biochemically, structurally, and functionally. Binding of {sup 125}I-(Tyr{sup 11})Somatostatin to AR4-2J cells was saturable, exhibiting a single class of high-affinity binding sites with a maximal binding capacity of 258 {plus minus} 20 fmol/10{sup 6} cells. Somatostatin receptor structure was analyzed by covalently cross-linking {sup 125}I-(Tyr{sup 11})somatostatin to its plasma membrane receptors. Gel electrophoresis and autoradiography of cross-linked proteins revealed a peptide containing the somatostatin receptor. Somatostatin inhibited vasoactive intestinal peptide (VIP)-stimulated adenosine 3{prime},5{prime}-cyclic monophosphate (cAMP) formation in a dose-dependent manner. The concentration of somatostatin that caused half-maximal inhibitionmore » of cAMP formation was close to the receptor affinity for somatostatin. Pertussis toxin pretreatment of AR4-2J cells prevented somatostatin inhibition of VIP-stimulated cAMP formation as well as somatostatin binding. The authors conclude that AR4-2J cells exhibit functional somatostatin receptors that retain both specificity and affinity of the pancreatic acinar cell somatostatin receptors and act via the pertussis toxin-sensitive guanine nucleotide-binding protein N{sub i} to inhibit adenylate cyclase.« less

Vascular effects of advanced glycation endproducts: Clinical effects and molecular mechanisms☆

PubMed Central

Stirban, Alin; Gawlowski, Thomas; Roden, Michael

2013-01-01

The enhanced generation and accumulation of advanced glycation endproducts (AGEs) have been linked to increased risk for macrovascular and microvascular complications associated with diabetes mellitus. AGEs result from the nonenzymatic reaction of reducing sugars with proteins, lipids, and nucleic acids, potentially altering their function by disrupting molecular conformation, promoting cross-linking, altering enzyme activity, reducing their clearance, and impairing receptor recognition. AGEs may also activate specific receptors, like the receptor for AGEs (RAGE), which is present on the surface of all cells relevant to atherosclerotic processes, triggering oxidative stress, inflammation and apoptosis. Understanding the pathogenic mechanisms of AGEs is paramount to develop strategies against diabetic and cardiovascular complications. PMID:24634815

Opioid receptor desensitization: mechanisms and its link to tolerance

PubMed Central

Allouche, Stéphane; Noble, Florence; Marie, Nicolas

2014-01-01

Opioid receptors (OR) 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. PMID:25566076

Individual stress vulnerability is predicted by short-term memory and AMPA receptor subunit ratio in the hippocampus.

PubMed

Schmidt, Mathias V; Trümbach, Dietrich; Weber, Peter; Wagner, Klaus; Scharf, Sebastian H; Liebl, Claudia; Datson, Nicole; Namendorf, Christian; Gerlach, Tamara; Kühne, Claudia; Uhr, Manfred; Deussing, Jan M; Wurst, Wolfgang; Binder, Elisabeth B; Holsboer, Florian; Müller, Marianne B

2010-12-15

Increased vulnerability to aversive experiences is one of the main risk factors for stress-related psychiatric disorders as major depression. However, the molecular bases of vulnerability, on the one hand, and stress resilience, on the other hand, are still not understood. Increasing clinical and preclinical evidence suggests a central involvement of the glutamatergic system in the pathogenesis of major depression. Using a mouse paradigm, modeling increased stress vulnerability and depression-like symptoms in a genetically diverse outbred strain, and we tested the hypothesis that differences in AMPA receptor function may be linked to individual variations in stress vulnerability. Vulnerable and resilient animals differed significantly in their dorsal hippocampal AMPA receptor expression and AMPA receptor binding. Treatment with an AMPA receptor potentiator during the stress exposure prevented the lasting effects of chronic social stress exposure on physiological, neuroendocrine, and behavioral parameters. In addition, spatial short-term memory, an AMPA receptor-dependent behavior, was found to be predictive of individual stress vulnerability and response to AMPA potentiator treatment. Finally, we provide evidence that genetic variations in the AMPA receptor subunit GluR1 are linked to the vulnerable phenotype. Therefore, we propose genetic variations in the AMPA receptor system to shape individual stress vulnerability. Those individual differences can be predicted by the assessment of short-term memory, thereby opening up the possibility for a specific treatment by enhancing AMPA receptor function.

Imprinting of metal receptors into multilayer polyelectrolyte films: fabrication and applications in marine antifouling† †Electronic supplementary information (ESI) available: FTIR, NMR spectra of synthesized polymers, XPS spectra and AFM images of non-cross linked and cross linked LBLA and LBLB films, UV-Visible absorption spectra of copper complexation with PAH-His, QCM data of LBLA and LBLB films and stability of the films are provided in the electronic supplementary information. See DOI: 10.1039/c4sc02367f Click here for additional data file.

PubMed Central

Puniredd, Sreenivasa Reddy; Go, Dewi Pitrasari; Zhu, Xiaoying; Guo, Shifeng; Ming Teo, Serena Lay; Chen Lee, Serina Siew

2015-01-01

Polymeric films constructed using the layer-by-layer (LbL) fabrication process were employed as a platform for metal ion immobilization and applied as a marine antifouling coating. The novel Cu2+ ion imprinting process described is based on the use of metal ion templates and LbL multilayer covalent cross-linking. Custom synthesized, peptide mimicking polycations composed of histidine grafted poly(allylamine) (PAH) to bind metal ions, and methyl ester containing polyanions for convenient cross-linking were used in the fabrication process. Two methods of LbL film formation have been investigated using alternate polyelectrolyte deposition namely non-imprinted LbLA, and imprinted LbLB. Both LbL films were cross linked at mild temperature to yield covalent bridging of the layers for improved stability in a sea water environment. A comparative study of the non-imprinted LbLA films and imprinted LbLB films for Cu2+ ion binding capacity, leaching rate and stability of the films was performed. The results reveal that the imprinted films possess enhanced affinity to retain metal ions due to the preorganization of imidazole bearing histidine receptors. As a result the binding capacity of the films for Cu2+ could be improved by seven fold. Antifouling properties of the resulting materials in a marine environment have been demonstrated against the settlement of barnacle larvae, indicating that controlled release of Cu ions was achieved. PMID:28966763

The Androgen Receptor Gene Mutations Database.

PubMed

Gottlieb, B; Lehvaslaiho, H; Beitel, L K; Lumbroso, R; Pinsky, L; Trifiro, M

1998-01-01

The current version of the androgen receptor (AR) gene mutations database is described. The total number of reported mutations has risen from 272 to 309 in the past year. We have expanded the database: (i) by giving each entry an accession number; (ii) by adding information on the length of polymorphic polyglutamine (polyGln) and polyglycine (polyGly) tracts in exon 1; (iii) by adding information on large gene deletions; (iv) by providing a direct link with a completely searchable database (courtesy EMBL-European Bioinformatics Institute). The addition of the exon 1 polymorphisms is discussed in light of their possible relevance as markers for predisposition to prostate or breast cancer. The database is also available on the internet (http://www.mcgill. ca/androgendb/ ), from EMBL-European Bioinformatics Institute (ftp. ebi.ac.uk/pub/databases/androgen ), or as a Macintosh FilemakerPro or Word file (MC33@musica.mcgill.ca).

The Androgen Receptor Gene Mutations Database.

PubMed Central

Gottlieb, B; Lehvaslaiho, H; Beitel, L K; Lumbroso, R; Pinsky, L; Trifiro, M

1998-01-01

The current version of the androgen receptor (AR) gene mutations database is described. The total number of reported mutations has risen from 272 to 309 in the past year. We have expanded the database: (i) by giving each entry an accession number; (ii) by adding information on the length of polymorphic polyglutamine (polyGln) and polyglycine (polyGly) tracts in exon 1; (iii) by adding information on large gene deletions; (iv) by providing a direct link with a completely searchable database (courtesy EMBL-European Bioinformatics Institute). The addition of the exon 1 polymorphisms is discussed in light of their possible relevance as markers for predisposition to prostate or breast cancer. The database is also available on the internet (http://www.mcgill. ca/androgendb/ ), from EMBL-European Bioinformatics Institute (ftp. ebi.ac.uk/pub/databases/androgen ), or as a Macintosh FilemakerPro or Word file (MC33@musica.mcgill.ca). PMID:9399843

Differential activation of natriuretic peptide receptors modulates cardiomyocyte proliferation during development

PubMed Central

Becker, Jason R.; Chatterjee, Sneha; Robinson, Tamara Y.; Bennett, Jeffrey S.; Panáková, Daniela; Galindo, Cristi L.; Zhong, Lin; Shin, Jordan T.; Coy, Shannon M.; Kelly, Amy E.; Roden, Dan M.; Lim, Chee Chew; MacRae, Calum A.

2014-01-01

Organ development is a highly regulated process involving the coordinated proliferation and differentiation of diverse cellular populations. The pathways regulating cell proliferation and their effects on organ growth are complex and for many organs incompletely understood. In all vertebrate species, the cardiac natriuretic peptides (ANP and BNP) are produced by cardiomyocytes in the developing heart. However, their role during cardiogenesis is not defined. Using the embryonic zebrafish and neonatal mammalian cardiomyocytes we explored the natriuretic peptide signaling network during myocardial development. We observed that the cardiac natriuretic peptides ANP and BNP and the guanylate cyclase-linked natriuretic peptide receptors Npr1 and Npr2 are functionally redundant during early cardiovascular development. In addition, we demonstrate that low levels of the natriuretic peptides preferentially activate Npr3, a receptor with Gi activator sequences, and increase cardiomyocyte proliferation through inhibition of adenylate cyclase. Conversely, high concentrations of natriuretic peptides reduce cardiomyocyte proliferation through activation of the particulate guanylate cyclase-linked natriuretic peptide receptors Npr1 and Npr2, and activation of protein kinase G. These data link the cardiac natriuretic peptides in a complex hierarchy modulating cardiomyocyte numbers during development through opposing effects on cardiomyocyte proliferation mediated through distinct cyclic nucleotide signaling pathways. PMID:24353062

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

PubMed

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) 5.55-100< pmol/mouse) than when administered i.t. (ED(50): 1.34-4.51 pmol/mouse). These results suggest the involvement of nociceptin-like agonistic effects of the Ac-RYYRIK pharmacophore in the peptides, 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.

GPCR & company: databases and servers for GPCRs and interacting partners.

PubMed

Kowalsman, Noga; Niv, Masha Y

2014-01-01

G-protein-coupled receptors (GPCRs) are a large superfamily of membrane receptors that are involved in a wide range of signaling pathways. To fulfill their tasks, GPCRs interact with a variety of partners, including small molecules, lipids and proteins. They are accompanied by different proteins during all phases of their life cycle. Therefore, GPCR interactions with their partners are of great interest in basic cell-signaling research and in drug discovery.Due to the rapid development of computers and internet communication, knowledge and data can be easily shared within the worldwide research community via freely available databases and servers. These provide an abundance of biological, chemical and pharmacological information.This chapter describes the available web resources for investigating GPCR interactions. We review about 40 freely available databases and servers, and provide a few sentences about the essence and the data they supply. For simplification, the databases and servers were grouped under the following topics: general GPCR-ligand interactions; particular families of GPCRs and their ligands; GPCR oligomerization; GPCR interactions with intracellular partners; and structural information on GPCRs. In conclusion, a multitude of useful tools are currently available. Summary tables are provided to ease navigation between the numerous and partially overlapping resources. Suggestions for future enhancements of the online tools include the addition of links from general to specialized databases and enabling usage of user-supplied template for GPCR structural modeling.

A dual chain chimeric antigen receptor (CAR) in the native antibody format for targeting immune cells towards cancer cells without the need of an scFv.

PubMed

Faitschuk, E; Nagy, V; Hombach, A A; Abken, H

2016-10-01

Adoptive cell therapy with chimeric antigen receptor (CAR)-modified T cells showed remarkable therapeutic efficacy in the treatment of leukaemia/lymphoma. However, the application to a variety of cancer entities is often constricted by the non-availability of a single chain antibody (scFv), which is usually the targeting domain in a CAR, while antibodies in the natural format are often available. To overcome the limitation, we designed a CAR that uses an antibody in its natural configuration for binding. Such CAR consists of two chains, the immunoglobulin light and heavy chain with their constant regions, whereby the heavy chain is anchored to the membrane and linked to an intracellular signalling domain for T-cell activation. The two chains form a stable heterodimer, a so-called dual chain CAR (dcCAR), and bind with high affinity and in a specific manner to their cognate antigen. By specific binding, the dcCAR activates engineered T cells for the release of pro-inflammatory cytokines and for target cell lysis. We provide evidence by three examples that the dcCAR format is universally applicable and thereby broadens the CAR cell therapy towards a larger variety of targets for which an scFv antibody is not available.

VEGF internalization is not required for VEGFR-2 phosphorylation in bioengineered surfaces with covalently linked VEGF

PubMed Central

Anderson, Sean M.; Shergill, Bhupinder; Barry, Zachary T.; Manousiouthakis, Eleana; Chen, Tom T.; Botvinick, Elliot; Platt, Manu O.; Iruela-Arispe, M. Luisa; Segura, Tatiana

2011-01-01

Vascular endothelial growth factor (VEGF) is known to activate proliferation, migration, and survival pathways in endothelial cells through phosphorylation of VEGF receptor-2 (VEGFR-2). VEGF has been incorporated into biomaterials through encapsulation, electrostatic sequestration, and covalent attachment, but the effect of these immobilization strategies on VEGF signaling has not been thoroughly investigated. Further, although growth factor internalization along with the receptor generally occurs in a physiological setting, whether this internalization is needed for receptor phosphorylation is not entirely clear. Here we show that VEGF covalently bound through a modified heparin molecule elicits an extended response of pVEGFR-2 in human umbilical vein endothelial cells (HUVECs) and that the covalent linkage reduces internalization of the growth factor during receptor endocytosis. Optical tweezer measurements show that the rupture force required to disrupt the heparin-VEGF-VEGFR-2 interaction increases from 3–8 pN to 6–12 pN when a covalent bond is introduced between VEGF and heparin. Importantly, by covalently binding VEGF to a heparin substrate, the stability (half-life) of VEGF is extended over three-fold. Here, mathematical models support the biological conclusions, further suggesting that VEGF internalization is significantly reduced when covalently bound, and indicating that VEGF is available for repeated phosphorylation events. PMID:21826315

GPCRM: a homology modeling web service with triple membrane-fitted quality assessment of GPCR models.

PubMed

Miszta, Przemyslaw; Pasznik, Pawel; Jakowiecki, Jakub; Sztyler, Agnieszka; Latek, Dorota; Filipek, Slawomir

2018-05-21

Due to the involvement of G protein-coupled receptors (GPCRs) in most of the physiological and pathological processes in humans they have been attracting a lot of attention from pharmaceutical industry as well as from scientific community. Therefore, the need for new, high quality structures of GPCRs is enormous. The updated homology modeling service GPCRM (http://gpcrm.biomodellab.eu/) meets those expectations by greatly reducing the execution time of submissions (from days to hours/minutes) with nearly the same average quality of obtained models. Additionally, due to three different scoring functions (Rosetta, Rosetta-MP, BCL::Score) it is possible to select accurate models for the required purposes: the structure of the binding site, the transmembrane domain or the overall shape of the receptor. Currently, no other web service for GPCR modeling provides this possibility. GPCRM is continually upgraded in a semi-automatic way and the number of template structures has increased from 20 in 2013 to over 90 including structures the same receptor with different ligands which can influence the structure not only in the on/off manner. Two types of protein viewers can be used for visual inspection of obtained models. The extended sortable tables with available templates provide links to external databases and display ligand-receptor interactions in visual form.

Striatal D1- and D2-type dopamine receptors are linked to motor response inhibition in human subjects.

PubMed

Robertson, Chelsea L; Ishibashi, Kenji; Mandelkern, Mark A; Brown, Amira K; Ghahremani, Dara G; Sabb, Fred; Bilder, Robert; Cannon, Tyrone; Borg, Jacqueline; London, Edythe D

2015-04-15

Motor response inhibition is mediated by neural circuits involving dopaminergic transmission; however, the relative contributions of dopaminergic signaling via D1- and D2-type receptors are unclear. Although evidence supports dissociable contributions of D1- and D2-type receptors to response inhibition in rats and associations of D2-type receptors to response inhibition in humans, the relationship between D1-type receptors and response inhibition has not been evaluated in humans. Here, we tested whether individual differences in striatal D1- and D2-type receptors are related to response inhibition in human subjects, possibly in opposing ways. Thirty-one volunteers participated. Response inhibition was indexed by stop-signal reaction time on the stop-signal task and commission errors on the continuous performance task, and tested for association with striatal D1- and D2-type receptor availability [binding potential referred to nondisplaceable uptake (BPND)], measured using positron emission tomography with [(11)C]NNC-112 and [(18)F]fallypride, respectively. Stop-signal reaction time was negatively correlated with D1- and D2-type BPND in whole striatum, with significant relationships involving the dorsal striatum, but not the ventral striatum, and no significant correlations involving the continuous performance task. The results indicate that dopamine D1- and D2-type receptors are associated with response inhibition, and identify the dorsal striatum as an important locus of dopaminergic control in stopping. Moreover, the similar contribution of both receptor subtypes suggests the importance of a relative balance between phasic and tonic dopaminergic activity subserved by D1- and D2-type receptors, respectively, in support of response inhibition. The results also suggest that the stop-signal task and the continuous performance task use different neurochemical mechanisms subserving motor response inhibition. Copyright © 2015 the authors 0270-6474/15/355990-08$15.00/0.

Enhanced Human-Type Receptor Binding by Ferret-Transmissible H5N1 with a K193T Mutation.

PubMed

Peng, Wenjie; Bouwman, Kim M; McBride, Ryan; Grant, Oliver C; Woods, Robert J; Verheije, Monique H; Paulson, James C; de Vries, Robert P

2018-05-15

All human influenza pandemics have originated from avian influenza viruses. Although multiple changes are needed for an avian virus to be able to transmit between humans, binding to human-type receptors is essential. Several research groups have reported mutations in H5N1 viruses that exhibit specificity for human-type receptors and promote respiratory droplet transmission between ferrets. Upon detailed analysis, we have found that these mutants exhibit significant differences in fine receptor specificity compared to human H1N1 and H3N2 and retain avian-type receptor binding. We have recently shown that human influenza viruses preferentially bind to α2-6-sialylated branched N-linked glycans, where the sialic acids on each branch can bind to receptor sites on two protomers of the same hemagglutinin (HA) trimer. In this binding mode, the glycan projects over the 190 helix at the top of the receptor-binding pocket, which in H5N1 would create a stearic clash with lysine at position 193. Thus, we hypothesized that a K193T mutation would improve binding to branched N-linked receptors. Indeed, the addition of the K193T mutation to the H5 HA of a respiratory-droplet-transmissible virus dramatically improves both binding to human trachea epithelial cells and specificity for extended α2-6-sialylated N-linked glycans recognized by human influenza viruses. IMPORTANCE Infections by avian H5N1 viruses are associated with a high mortality rate in several species, including humans. Fortunately, H5N1 viruses do not transmit between humans because they do not bind to human-type receptors. In 2012, three seminal papers have shown how these viruses can be engineered to transmit between ferrets, the human model for influenza virus infection. Receptor binding, among others, was changed, and the viruses now bind to human-type receptors. Receptor specificity was still markedly different compared to that of human influenza viruses. Here we report an additional mutation in ferret-transmissible H5N1 that increases human-type receptor binding. K193T seems to be a common receptor specificity determinant, as it increases human-type receptor binding in multiple subtypes. The K193T mutation can now be used as a marker during surveillance of emerging viruses to assess potential pandemic risk. Copyright © 2018 American Society for Microbiology.

Neurotensin receptor 1 gene activation by the Tcf/beta-catenin pathway is an early event in human colonic adenomas.

PubMed

Souazé, Frédérique; Viardot-Foucault, Véronique; Roullet, Nicolas; Toy-Miou-Leong, Mireille; Gompel, Anne; Bruyneel, Erik; Comperat, Eva; Faux, Maree C; Mareel, Marc; Rostène, William; Fléjou, Jean-François; Gespach, Christian; Forgez, Patricia

2006-04-01

Alterations in the Wnt/APC (adenomatous polyposis coli) signalling pathway, resulting in beta-catenin/T cell factor (Tcf)-dependent transcriptional gene activation, are frequently detected in familial and sporadic colon cancers. The neuropeptide neurotensin (NT) is widely distributed in the gastrointestinal tract. Its proliferative and survival effects are mediated by a G-protein coupled receptor, the NT1 receptor. NT1 receptor is not expressed in normal colon epithelial cells, but is over expressed in a number of cancer cells and tissues suggesting a link to the outgrowth of human colon cancer. Our results demonstrate that the upregulation of NT1 receptor occurring in colon cancer is the result of Wnt/APC signalling pathway activation. We first established the functionality of the Tcf response element within the NT1 receptor promoter. Consequently, we observed the activation of NT1 receptor gene by agents causing beta-catenin cytosolic accumulation, as well as a strong decline of endogenous receptor when wt-APC was restored. At the cellular level, the re-establishment of wt-APC phenotype resulted in the impaired functionality of NT1 receptor, like the breakdown in NT-induced intracellular calcium mobilization and the loss of NT pro-invasive effect. We corroborated the Wnt/APC signalling pathway on the NT1 receptor promoter activation with human colon carcinogenesis, and showed that NT1 receptor gene activation was perfectly correlated with nuclear or cytoplasmic beta-catenin localization while NT1 receptor was absent when beta-catenin was localized at the cell-cell junction in early adenomas of patients with familial adenomatous polyposis, hereditary non-polyposis colorectal cancer and loss of heterozygosity tumours. In this report we establish a novel link in vitro between the Tcf/beta-catenin pathway and NT1 receptor promoter activation.

The role of androgens and polymorphisms in the androgen receptor in the epidemiology of breast cancer

PubMed Central

Lillie, Elizabeth O; Bernstein, Leslie; Ursin, Giske

2003-01-01

Testosterone binds to the androgen receptor in target tissue to mediate its effects. Variations in testosterone levels and androgen receptor activity may play a role in the etiology of breast cancer. Here, we review the epidemiologic evidence linking endogenous testosterone to breast cancer risk. Paradoxically, results from observational studies that have examined polymorphisms in the androgen receptor suggest that the low-activity androgen receptor increases breast cancer risk. We review the quality of this evidence and conclude with a discussion of how the androgen receptor and testosterone results coincide. PMID:12793900

Trifunctional Agents as a Design Strategy for Tailoring Ligand Properties: Irreversible Inhibitors of A1 Adenosine Receptors†

PubMed Central

Boring, Daniel L.; Ji, Xiao-Duo; Zimmet, Jeff; Taylor, Kirk E.; Stiles, Gary L.

2012-01-01

The 1,3-phenylene diisothiocyanate conjugate of XAC (8-[4-[[[[(2-aminoethyl)amino]carbonyl]methyl]-oxy]phenyl]-l,3-dipropylxanthine, a potent A1 selective adenosine antagonist) has been characterized as an irreversible inhibitor of A1 adenosine receptors. To further extend this work, a series of analogues were prepared containing a third substituent in the phenyl isothiocyanate ring, incorporated to modify the physiochemical or spectroscopic properties of the conjugate. Symmetrical trifunctional cross-linking reagents bearing two isothiocyanate groups were prepared as general intermediates for cross-linking functionalized congeners and receptors. Xanthine isothiocyanate derivatives containing hydrophilic, fluorescent, or reactive substituents, linked via an amide, thiourea, or methylene group in the 5-position, were synthesized and found to be irreversible inhibitors of A1 adenosine receptors. The effects of the 5-substituent on water solubility and on the A1/A2 selectivity ratio derived from binding assays in rat brain membranes were examined. Inhibition of binding of [3H]-N6-(2-phenylisopropyl)-adenosine and [3H]CGS21680 (2-[[2-[4-(2-carboxyethyl)phenyl]ethyl]amino]adenosine-5′-N-ethylcarboxamide) at central A1 and A2 adenosine receptors, respectively, was measured. A conjugate of XAC and 1,3,5-triisothiocyanatobenzene was 894-fold selective for A1 receptors. Reporter groups, such as fluorescent dyes and a spin-label, were included as chain substituents in the irreversibly binding analogues, which were designed for spectroscopic assays, histochemical characterization, and biochemical characterization of the receptor protein. PMID:1868116

Angptl4 does not control hyperglucagonemia or α-cell hyperplasia following glucagon receptor inhibition

PubMed Central

Okamoto, Haruka; Cavino, Katie; Na, Erqian; Krumm, Elizabeth; Kim, Steven; Stevis, Panayiotis E.; Harp, Joyce; Murphy, Andrew J.; Yancopoulos, George D.; Gromada, Jesper

2017-01-01

Genetic disruption or pharmacologic inhibition of glucagon signaling effectively lowers blood glucose but results in compensatory glucagon hypersecretion involving expansion of pancreatic α-cell mass. Ben-Zvi et al. recently reported that angiopoietin-like protein 4 (Angptl4) links glucagon receptor inhibition to hyperglucagonemia and α-cell proliferation [Ben-Zvi et al. (2015) Proc Natl Acad Sci USA 112:15498–15503]. Angptl4 is a secreted protein and inhibitor of lipoprotein lipase-mediated plasma triglyceride clearance. We report that Angptl4−/− mice treated with an anti-glucagon receptor monoclonal antibody undergo elevation of plasma glucagon levels and α-cell expansion similar to wild-type mice. Overexpression of Angptl4 in liver of mice caused a 8.6-fold elevation in plasma triglyceride levels, but did not alter plasma glucagon levels or α-cell mass. Furthermore, administration of glucagon receptor-blocking antibody to healthy individuals increased plasma glucagon and amino acid levels, but did not change circulating Angptl4 concentration. These data show that Angptl4 does not link glucagon receptor inhibition to compensatory hyperglucagonemia or expansion of α-cell mass, and that it cannot be given to induce such secretion and growth. The reduction of plasma triglyceride levels in Angptl4−/− mice and increase following Angptl4 overexpression suggest that changes in plasma triglyceride metabolism do not regulate α-cells in the pancreas. Our findings corroborate recent data showing that increased plasma amino acids and their transport into α-cells link glucagon receptor blockage to α-cell hyperplasia. PMID:28143927

Gene Transfer and Molecular Cloning of the Human NGF Receptor

NASA Astrophysics Data System (ADS)

Chao, Moses V.; Bothwell, Mark A.; Ross, Alonzo H.; Koprowski, Hilary; Lanahan, Anthony A.; Buck, C. Randall; Sehgal, Amita

1986-04-01

Nerve growth factor (NGF) and its receptor are important in the development of cells derived from the neural crest. Mouse L cell transformants have been generated that stably express the human NGF receptor gene transfer with total human DNA. Affinity cross-linking, metabolic labeling and immunoprecipitation, and equilibrium binding with 125I-labeled NGF revealed that this NGF receptor had the same size and binding characteristics as the receptor from human melanoma cells and rat PC12 cells. The sequences encoding the NGF receptor were molecularly cloned using the human Alu repetitive sequence as a probe. A cosmid clone that contained the human NGF receptor gene allowed efficient transfection and expression of the receptor.

EPA EcoBox Tools by Receptors - Receptors in ERA

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Glutamate and Neurodegenerative Disease

NASA Astrophysics Data System (ADS)

Schaeffer, Eric; Duplantier, Allen

As the main excitatory neurotransmitter in the mammalian central nervous system, glutamate is critically involved in most aspects of CNS function. Given this critical role, it is not surprising that glutamatergic dysfunction is associated with many CNS disorders. In this chapter, we review the literature that links aberrant glutamate neurotransmission with CNS pathology, with a focus on neurodegenerative diseases. The biology and pharmacology of the various glutamate receptor families are discussed, along with data which links these receptors with neurodegenerative conditions. In addition, we review progress that has been made in developing small molecule modulators of glutamate receptors and transporters, and describe how these compounds have helped us understand the complex pharmacology of glutamate in normal CNS function, as well as their potential for the treatment of neurodegenerative diseases.

N-linked oligosaccharides on the low density lipoprotein receptor homolog SorLA/LR11 are modified with terminal GalNAc-4-SO4 in kidney and brain.

PubMed

Fiete, Dorothy; Mi, Yiling; Oats, Edward L; Beranek, Mary C; Baenziger, Jacques U

2007-01-19

Sorting protein-related receptor (SorLA/LR11) is a highly conserved mosaic receptor that is expressed by cells in a number of different tissues including principal cells of the collecting ducts in the kidney and neurons in the central and peripheral nervous systems. SorLA/LR11 has features that indicate it serves as a sorting receptor shuttling between the plasma membrane, endosomes, and the Golgi. We have found that a fraction of SorLA/LR11 that is synthesized in the kidney and the brain bears N-linked oligosaccharides that are modified with terminal beta1,4-linked GalNAc-4-SO(4). Oligosaccharides located in the vacuolar sorting (Vps) 10p domain (Vps10p domain) are modified with beta1,4-linked GalNAc when the Vps10p domain is expressed in cells along with either of two recently cloned protein-specific beta1,4GalNAc-transferases, GalNAcTIII and GalNAcTIV. Either of two sequences with basic amino acids located within the Vps10p domain is able to mediate recognition by these beta1,4GalNAc-transferases. The highly specific modification of oligosaccharides in the Vps10p domain of SorLA/LR11 with terminal GalNAc-4-SO(4) suggests that this unusual modification may modulate the interaction of SorLA/LR11 with proteins and influence their trafficking.

G-Protein/β-Arrestin-Linked Fluctuating Network of G-Protein-Coupled Receptors for Predicting Drug Efficacy and Bias Using Short-Term Molecular Dynamics Simulation

PubMed Central

Ichikawa, Osamu; Fujimoto, Kazushi; Yamada, Atsushi; Okazaki, Susumu; Yamazaki, Kazuto

2016-01-01

The efficacy and bias of signal transduction induced by a drug at a target protein are closely associated with the benefits and side effects of the drug. In particular, partial agonist activity and G-protein/β-arrestin-biased agonist activity for the G-protein-coupled receptor (GPCR) family, the family with the most target proteins of launched drugs, are key issues in drug discovery. However, designing GPCR drugs with appropriate efficacy and bias is challenging because the dynamic mechanism of signal transduction induced by ligand—receptor interactions is complicated. Here, we identified the G-protein/β-arrestin-linked fluctuating network, which initiates large-scale conformational changes, using sub-microsecond molecular dynamics (MD) simulations of the β2-adrenergic receptor (β2AR) with a diverse collection of ligands and correlation analysis of their G protein/β-arrestin efficacy. The G-protein-linked fluctuating network extends from the ligand-binding site to the G-protein-binding site through the connector region, and the β-arrestin-linked fluctuating network consists of the NPxxY motif and adjacent regions. We confirmed that the averaged values of fluctuation in the fluctuating network detected are good quantitative indexes for explaining G protein/β-arrestin efficacy. These results indicate that short-term MD simulation is a practical method to predict the efficacy and bias of any compound for GPCRs. PMID:27187591

Visualization of arrestin recruitment by a G Protein-Coupled Receptor

PubMed Central

Reis, Rosana I.; Huang, Li-Yin; Tripathi-Shukla, Prachi; Qian, Jiang; Li, Sheng; Blanc, Adi; Oleskie, Austin N.; Dosey, Anne M.; Su, Min; Liang, Cui-Rong; Gu, Ling-Ling; Shan, Jin-Ming; Chen, Xin; Hanna, Rachel; Choi, Minjung; Yao, Xiao Jie; Klink, Bjoern U.; Kahsai, Alem W.; Sidhu, Sachdev S.; Koide, Shohei; Penczek, Pawel A.; Kossiakoff, Anthony A.; Jr, Virgil L. Woods; Kobilka, Brian K.; Skiniotis, Georgios; Lefkowitz, Robert J.

2014-01-01

G Protein Coupled Receptors (GPCRs) are critically regulated by β-arrestins (βarrs), which not only desensitize G protein signaling but also initiate a G protein independent wave of signaling1-5. A recent surge of structural data on a number of GPCRs, including the β2 adrenergic receptor (β2AR)-G protein complex, has provided novel insights into the structural basis of receptor activation6-11. Lacking however has been complementary information on recruitment of βarrs to activated GPCRs primarily due to challenges in obtaining stable receptor-βarr complexes for structural studies. Here, we devised a strategy for forming and purifying a functional β2AR-βarr1 complex that allowed us to visualize its architecture by single particle negative stain electron microscopy (EM) and to characterize the interactions between β2AR and βarr1 using hydrogen-deuterium exchange mass spectrometry (HDXMS) and chemical cross-linking. EM 2D averages and 3D reconstructions reveal bimodal binding of βarr1 to the β2AR, involving two separate sets of interactions, one with the phosphorylated carboxy-terminus of the receptor and the other with its seven-transmembrane core. Areas of reduced HDX together with identification of cross-linked residues suggest engagement of the finger loop of βarr1 with the seven-transmembrane core of the receptor. In contrast, focal areas of increased HDX indicate regions of increased dynamics in both N and C domains of βarr1 when coupled to the β2AR. A molecular model of the β2AR-βarr signaling complex was made by docking activated βarr1 and β2AR crystal structures into the EM map densities with constraints provided by HDXMS and cross-linking, allowing us to obtain valuable insights into the overall architecture of a receptor-arrestin complex. The dynamic and structural information presented herein provides a framework for better understanding the basis of GPCR regulation by arrestins. PMID:25043026

Structural Basis for a Switch in Receptor Binding Specificity of Two H5N1 Hemagglutinin Mutants

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

Zhu, Xueyong; Viswanathan, Karthik; Raman, Rahul

Avian H5N1 influenza viruses continue to spread in wild birds and domestic poultry with sporadic infection in humans. Receptor binding specificity changes are a prerequisite for H5N1 viruses and other zoonotic viruses to be transmitted among humans. Previous reported hemagglutinin (HA) mutants from ferret-transmissible H5N1 viruses of A/Viet Nam/1203/04 and A/Indonesia/5/05 showed slightly increased, but still very weak, binding to human receptors. From mutagenesis and glycan array studies, we previously identified two H5N1 HA mutants that could more effectively switch receptor specificity to human-like α2-6 linked sialosides with avidity comparable to wild-type H5 HA binding to avian-like α2-3 linked sialosides.more » Here, crystal structures of these two H5 HA mutants free and in complex with human and avian glycan receptor analogues reveal the structural basis for their preferential binding to human receptors. These findings suggest continuous surveillance should be maintained to monitor and assess human-to-human transmission potential of H5N1 viruses.« less

Activation of mas-related G-protein-coupled receptors by the house dust mite cysteine protease Der p1 provides a new mechanism linking allergy and inflammation.

PubMed

Reddy, Vemuri B; Lerner, Ethan A

2017-10-20

Cysteine and serine proteases function via protease-activated and mas-related G-protein-coupled receptors (Mrgprs) to contribute to allergy and inflammation. Der p1 is a cysteine protease and major allergen from the house dust mite and is associated with allergic rhinitis and allergic asthma. Der p1 activates protease-activated receptor 2 and induces the release of the pro-inflammatory cytokine IL-6 from cells. However, the possibility that Der p1 acts on Mrgprs has not been considered. We report here that ratiometric calcium imaging reveals that Der p1 activates the human receptor MRGPRX1 and the mouse homolog MrgprC11, implicated previously in itch. Der p1 cleavage of N-terminal receptor peptides followed by site-directed mutagenesis of the cleavage sites links receptor activation to specific amino acid residues. Der p1 also induced the release of IL-6 from heterologous cells expressing MRGPRX1. In summary, activation of Mrgprs by the allergen Der p1 may contribute to inflammation. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Structural Basis for a Switch in Receptor Binding Specificity of Two H5N1 Hemagglutinin Mutants

DOE PAGES

Zhu, Xueyong; Viswanathan, Karthik; Raman, Rahul; ...

2015-11-01

Avian H5N1 influenza viruses continue to spread in wild birds and domestic poultry with sporadic infection in humans. Receptor binding specificity changes are a prerequisite for H5N1 viruses and other zoonotic viruses to be transmitted among humans. Previous reported hemagglutinin (HA) mutants from ferret-transmissible H5N1 viruses of A/Viet Nam/1203/04 and A/Indonesia/5/05 showed slightly increased, but still very weak, binding to human receptors. From mutagenesis and glycan array studies, we previously identified two H5N1 HA mutants that could more effectively switch receptor specificity to human-like α2-6 linked sialosides with avidity comparable to wild-type H5 HA binding to avian-like α2-3 linked sialosides.more » Here, crystal structures of these two H5 HA mutants free and in complex with human and avian glycan receptor analogues reveal the structural basis for their preferential binding to human receptors. These findings suggest continuous surveillance should be maintained to monitor and assess human-to-human transmission potential of H5N1 viruses.« less

Nck recruitment to Eph receptor, EphB1/ELK, couples ligand activation to c-Jun kinase.

PubMed

Stein, E; Huynh-Do, U; Lane, A A; Cerretti, D P; Daniel, T O

1998-01-16

Eph family receptor tyrosine kinases signal axonal guidance, neuronal bundling, and angiogenesis; yet the signaling systems that couple these receptors to targeting and cell-cell assembly responses are incompletely defined. Functional links to regulators of cytoskeletal structure are anticipated based on receptor mediated cell-cell aggregation and migratory responses. We used two-hybrid interaction cloning to identify EphB1-interactive proteins. Six independent cDNAs encoding the SH2 domain of the adapter protein, Nck, were recovered in a screen of a murine embryonic library. We mapped the EphB1 subdomain that binds Nck and its Drosophila homologue, DOCK, to the juxtamembrane region. Within this subdomain, Tyr594 was required for Nck binding. In P19 embryonal carcinoma cells, activation of EphB1 (ELK) by its ligand, ephrin-B1/Fc, recruited Nck to native receptor complexes and activated c-Jun kinase (JNK/SAPK). Transient overexpression of mutant EphB1 receptors (Y594F) blocked Nck recruitment to EphB1, attenuated downstream JNK activation, and blocked cell attachment responses. These findings identify Nck as an important intermediary linking EphB1 signaling to JNK.

Research Resource: A Reference Transcriptome for Constitutive Androstane Receptor and Pregnane X Receptor Xenobiotic Signaling

PubMed Central

Ochsner, Scott A.; Tsimelzon, Anna; Dong, Jianrong; Coarfa, Cristian

2016-01-01

The pregnane X receptor (PXR) (PXR/NR1I3) and constitutive androstane receptor (CAR) (CAR/NR1I2) members of the nuclear receptor (NR) superfamily of ligand-regulated transcription factors are well-characterized mediators of xenobiotic and endocrine-disrupting chemical signaling. The Nuclear Receptor Signaling Atlas maintains a growing library of transcriptomic datasets involving perturbations of NR signaling pathways, many of which involve perturbations relevant to PXR and CAR xenobiotic signaling. Here, we generated a reference transcriptome based on the frequency of differential expression of genes across 159 experiments compiled from 22 datasets involving perturbations of CAR and PXR signaling pathways. In addition to the anticipated overrepresentation in the reference transcriptome of genes encoding components of the xenobiotic stress response, the ranking of genes involved in carbohydrate metabolism and gonadotropin action sheds mechanistic light on the suspected role of xenobiotics in metabolic syndrome and reproductive disorders. Gene Set Enrichment Analysis showed that although acetaminophen, chlorpromazine, and phenobarbital impacted many similar gene sets, differences in direction of regulation were evident in a variety of processes. Strikingly, gene sets representing genes linked to Parkinson's, Huntington's, and Alzheimer's diseases were enriched in all 3 transcriptomes. The reference xenobiotic transcriptome will be supplemented with additional future datasets to provide the community with a continually updated reference transcriptomic dataset for CAR- and PXR-mediated xenobiotic signaling. Our study demonstrates how aggregating and annotating transcriptomic datasets, and making them available for routine data mining, facilitates research into the mechanisms by which xenobiotics and endocrine-disrupting chemicals subvert conventional NR signaling modalities. PMID:27409825

Role of BMP receptor traffic in synaptic growth defects in an ALS model.

PubMed

Deshpande, Mugdha; Feiger, Zachary; Shilton, Amanda K; Luo, Christina C; Silverman, Ethan; Rodal, Avital A

2016-10-01

TAR DNA-binding protein 43 (TDP-43) is genetically and functionally linked to amyotrophic lateral sclerosis (ALS) and regulates transcription, splicing, and transport of thousands of RNA targets that function in diverse cellular pathways. In ALS, pathologically altered TDP-43 is believed to lead to disease by toxic gain-of-function effects on RNA metabolism, as well as by sequestering endogenous TDP-43 and causing its loss of function. However, it is unclear which of the numerous cellular processes disrupted downstream of TDP-43 dysfunction lead to neurodegeneration. Here we found that both loss and gain of function of TDP-43 in Drosophila cause a reduction of synaptic growth-promoting bone morphogenic protein (BMP) signaling at the neuromuscular junction (NMJ). Further, we observed a shift of BMP receptors from early to recycling endosomes and increased mobility of BMP receptor-containing compartments at the NMJ. Inhibition of the recycling endosome GTPase Rab11 partially rescued TDP-43-induced defects in BMP receptor dynamics and distribution and suppressed BMP signaling, synaptic growth, and larval crawling defects. Our results indicate that defects in receptor traffic lead to neuronal dysfunction downstream of TDP-43 misregulation and that rerouting receptor traffic may be a viable strategy for rescuing neurological impairment. © 2016 Deshpande, Feiger, et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Research Resource: A Reference Transcriptome for Constitutive Androstane Receptor and Pregnane X Receptor Xenobiotic Signaling.

PubMed

Ochsner, Scott A; Tsimelzon, Anna; Dong, Jianrong; Coarfa, Cristian; McKenna, Neil J

2016-08-01

The pregnane X receptor (PXR) (PXR/NR1I3) and constitutive androstane receptor (CAR) (CAR/NR1I2) members of the nuclear receptor (NR) superfamily of ligand-regulated transcription factors are well-characterized mediators of xenobiotic and endocrine-disrupting chemical signaling. The Nuclear Receptor Signaling Atlas maintains a growing library of transcriptomic datasets involving perturbations of NR signaling pathways, many of which involve perturbations relevant to PXR and CAR xenobiotic signaling. Here, we generated a reference transcriptome based on the frequency of differential expression of genes across 159 experiments compiled from 22 datasets involving perturbations of CAR and PXR signaling pathways. In addition to the anticipated overrepresentation in the reference transcriptome of genes encoding components of the xenobiotic stress response, the ranking of genes involved in carbohydrate metabolism and gonadotropin action sheds mechanistic light on the suspected role of xenobiotics in metabolic syndrome and reproductive disorders. Gene Set Enrichment Analysis showed that although acetaminophen, chlorpromazine, and phenobarbital impacted many similar gene sets, differences in direction of regulation were evident in a variety of processes. Strikingly, gene sets representing genes linked to Parkinson's, Huntington's, and Alzheimer's diseases were enriched in all 3 transcriptomes. The reference xenobiotic transcriptome will be supplemented with additional future datasets to provide the community with a continually updated reference transcriptomic dataset for CAR- and PXR-mediated xenobiotic signaling. Our study demonstrates how aggregating and annotating transcriptomic datasets, and making them available for routine data mining, facilitates research into the mechanisms by which xenobiotics and endocrine-disrupting chemicals subvert conventional NR signaling modalities.

Immunocytochemical assessment of sigma-1 receptor and human sterol isomerase in breast cancer and their relationship with a series of prognostic factors

PubMed Central

Simony-Lafontaine, J; Esslimani, M; Bribes, E; Gourgou, S; Lequeux, N; Lavail, R; Grenier, J; Kramar, A; Casellas, P

2000-01-01

The purpose of this study was to immunocytochemically investigate two new markers, the sigma-1 receptor and the human sterol isomerase (hSI), in comparison with a series of clinicopathological and immunocytochemical prognostic factors in a trial including 95 patients with operable primary breast cancers. Our results showed no statistically significant relationship between these two markers and the age of the patients, their menopausal status, the tumour size and its histological grade, the nodal status and the expression of the Ki-67 proliferative marker. However, we evidenced a close correlation between the sigma-1 receptor expression and the hormonal receptor positivity (P = 0.008), essentially due to a link with the progesterone receptor status (P = 0.01). By contrast there was an inverse relationship between hSI expression and the oestrogen receptor and/or progesterone receptor positivity (P = 0.098). A significant relationship was shown between both the sigma-1 receptor, hSI expressions and Bcl2 expression, with P = 0.017 and 0.035 respectively. We also assessed whether the expression of the sigma-1 receptor or hSI might be linked with disease-free survival (DFS) and found that the presence of hSI and the absence of sigma-1 receptor expression were associated with a poorer disease-free survival (P = 0.007). Altogether these results suggest that in primary breast carcinomas in association with the evaluation of the steroid receptor status, the sigma-1 receptor and hSI may be interesting new markers useful to identify those patients who might be able to benefit from an adjuvant therapy. © 2000 Cancer Research Campaign PMID:10864204

Influenza immunization elicits antibodies specific for an egg-adapted vaccine strain.

PubMed

Raymond, Donald D; Stewart, Shaun M; Lee, Jiwon; Ferdman, Jack; Bajic, Goran; Do, Khoi T; Ernandes, Michael J; Suphaphiphat, Pirada; Settembre, Ethan C; Dormitzer, Philip R; Del Giudice, Giuseppe; Finco, Oretta; Kang, Tae Hyun; Ippolito, Gregory C; Georgiou, George; Kepler, Thomas B; Haynes, Barton F; Moody, M Anthony; Liao, Hua-Xin; Schmidt, Aaron G; Harrison, Stephen C

2016-12-01

For broad protection against infection by viruses such as influenza or HIV, vaccines should elicit antibodies that bind conserved viral epitopes, such as the receptor-binding site (RBS). RBS-directed antibodies have been described for both HIV and influenza virus, and the design of immunogens to elicit them is a goal of vaccine research in both fields. Residues in the RBS of influenza virus hemagglutinin (HA) determine a preference for the avian or human receptor, α-2,3-linked sialic acid and α-2,6-linked sialic acid, respectively. Transmission of an avian-origin virus between humans generally requires one or more mutations in the sequences encoding the influenza virus RBS to change the preferred receptor from avian to human, but passage of a human-derived vaccine candidate in chicken eggs can select for reversion to avian receptor preference. For example, the X-181 strain of the 2009 new pandemic H1N1 influenza virus, derived from the A/California/07/2009 isolate and used in essentially all vaccines since 2009, has arginine at position 226, a residue known to confer preference for an α-2,3 linkage in H1 subtype viruses; the wild-type A/California/07/2009 isolate, like most circulating human H1N1 viruses, has glutamine at position 226. We describe, from three different individuals, RBS-directed antibodies that recognize the avian-adapted H1 strain in current influenza vaccines but not the circulating new pandemic 2009 virus; Arg226 in the vaccine-strain RBS accounts for the restriction. The polyclonal sera of the three donors also reflect this preference. Therefore, when vaccines produced from strains that are never passaged in avian cells become widely available, they may prove more capable of eliciting RBS-directed, broadly neutralizing antibodies than those produced from egg-adapted viruses, extending the established benefits of current seasonal influenza immunizations.

NMDA Receptor Autoantibodies in Autoimmune Encephalitis Cause a Subunit-Specific Nanoscale Redistribution of NMDA Receptors.

PubMed

Ladépêche, Laurent; Planagumà, Jesús; Thakur, Shreyasi; Suárez, Irina; Hara, Makoto; Borbely, Joseph Steven; Sandoval, Angel; Laparra-Cuervo, Lara; Dalmau, Josep; Lakadamyali, Melike

2018-06-26

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a severe neuropsychiatric disorder mediated by autoantibodies against the GluN1 subunit of the NMDAR. Patients' antibodies cause cross-linking and internalization of NMDAR, but the synaptic events leading to depletion of NMDAR are poorly understood. Using super-resolution microscopy, we studied the effects of the autoantibodies on the nanoscale distribution of NMDAR in cultured neurons. Our findings show that, under control conditions, NMDARs form nanosized objects and patients' antibodies increase the clustering of synaptic and extrasynaptic receptors inside the nano-objects. This clustering is subunit specific and predominantly affects GluN2B-NMDARs. Following internalization, the remaining surface NMDARs return to control clustering levels but are preferentially retained at the synapse. Monte Carlo simulations using a model in which antibodies induce NMDAR cross-linking and disruption of interactions with other proteins recapitulated these results. Finally, activation of EphB2 receptor partially antagonized the antibody-mediated disorganization of the nanoscale surface distribution of NMDARs. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Cell-specific targeting by heterobivalent ligands.

PubMed

Josan, Jatinder S; Handl, Heather L; Sankaranarayanan, Rajesh; Xu, Liping; Lynch, Ronald M; Vagner, Josef; Mash, Eugene A; Hruby, Victor J; Gillies, Robert J

2011-07-20

Current cancer therapies exploit either differential metabolism or targeting to specific individual gene products that are overexpressed in aberrant cells. The work described herein proposes an alternative approach--to specifically target combinations of cell-surface receptors using heteromultivalent ligands ("receptor combination approach"). As a proof-of-concept that functionally unrelated receptors can be noncovalently cross-linked with high avidity and specificity, a series of heterobivalent ligands (htBVLs) were constructed from analogues of the melanocortin peptide ligand ([Nle(4), dPhe(7)]-α-MSH) and the cholecystokinin peptide ligand (CCK-8). Binding of these ligands to cells expressing the human Melanocortin-4 receptor and the Cholecystokinin-2 receptor was analyzed. The MSH(7) and CCK(6) were tethered with linkers of varying rigidity and length, constructed from natural and/or synthetic building blocks. Modeling data suggest that a linker length of 20-50 Å is needed to simultaneously bind these two different G-protein coupled receptors (GPCRs). These ligands exhibited up to 24-fold enhancement in binding affinity to cells that expressed both (bivalent binding), compared to cells with only one (monovalent binding) of the cognate receptors. The htBVLs had up to 50-fold higher affinity than that of a monomeric CCK ligand, i.e., Ac-CCK(6)-NH(2). Cell-surface targeting of these two cell types with labeled heteromultivalent ligand demonstrated high avidity and specificity, thereby validating the receptor combination approach. This ability to noncovalently cross-link heterologous receptors and target individual cells using a receptor combination approach opens up new possibilities for specific cell targeting in vivo for therapy or imaging.

Cell-Specific Targeting by Heterobivalent Ligands

PubMed Central

Josan, Jatinder S.; Handl, Heather L.; Sankaranarayanan, Rajesh; Xu, Liping; Lynch, Ronald M.; Vagner, Josef; Mash, Eugene A.; Hruby, Victor J.; Gillies, Robert J.

2012-01-01

Current cancer therapies exploit either differential metabolism or targeting to specific individual gene products that are overexpressed in aberrant cells. The work described herein proposes an alternative approach—to specifically target combinations of cell-surface receptors using heteromultivalent ligands (“receptor combination approach”). As a proof-of-concept that functionally unrelated receptors can be noncovalently cross-linked with high avidity and specificity, a series of heterobivalent ligands (htBVLs) were constructed from analogues of the melanocortin peptide ligand ([Nle4, DPhe7]-α-MSH) and the cholecystokinin peptide ligand (CCK-8). Binding of these ligands to cells expressing the human Melanocortin-4 receptor and the Cholecystokinin-2 receptor was analyzed. The MSH(7) and CCK(6) were tethered with linkers of varying rigidity and length, constructed from natural and/or synthetic building blocks. Modeling data suggest that a linker length of 20–50 Å is needed to simultaneously bind these two different G-protein coupled receptors (GPCRs). These ligands exhibited up to 24-fold enhancement in binding affinity to cells that expressed both (bivalent binding), compared to cells with only one (monovalent binding) of the cognate receptors. The htBVLs had up to 50-fold higher affinity than that of a monomeric CCK ligand, i.e., Ac-CCK(6)-NH2. Cell-surface targeting of these two cell types with labeled heteromultivalent ligand demonstrated high avidity and specificity, thereby validating the receptor combination approach. This ability to noncovalently cross-link heterologous receptors and target individual cells using a receptor combination approach opens up new possibilities for specific cell targeting in vivo for therapy or imaging. PMID:21639139

Structural Basis of G Protein-coupled Receptor-Gi Protein Interaction

PubMed Central

Mnpotra, Jagjeet S.; Qiao, Zhuanhong; Cai, Jian; Lynch, Diane L.; Grossfield, Alan; Leioatts, Nicholas; Hurst, Dow P.; Pitman, Michael C.; Song, Zhao-Hui; Reggio, Patricia H.

2014-01-01

In this study, we applied a comprehensive G protein-coupled receptor-Gαi protein chemical cross-linking strategy to map the cannabinoid receptor subtype 2 (CB2)- Gαi interface and then used molecular dynamics simulations to explore the dynamics of complex formation. Three cross-link sites were identified using LC-MS/MS and electrospray ionization-MS/MS as follows: 1) a sulfhydryl cross-link between C3.53(134) in TMH3 and the Gαi C-terminal i-3 residue Cys-351; 2) a lysine cross-link between K6.35(245) in TMH6 and the Gαi C-terminal i-5 residue, Lys-349; and 3) a lysine cross-link between K5.64(215) in TMH5 and the Gαi α4β6 loop residue, Lys-317. To investigate the dynamics and nature of the conformational changes involved in CB2·Gi complex formation, we carried out microsecond-time scale molecular dynamics simulations of the CB2 R*·Gαi1β1γ2 complex embedded in a 1-palmitoyl-2-oleoyl-phosphatidylcholine bilayer, using cross-linking information as validation. Our results show that although molecular dynamics simulations started with the G protein orientation in the β2-AR*·Gαsβ1γ2 complex crystal structure, the Gαi1β1γ2 protein reoriented itself within 300 ns. Two major changes occurred as follows. 1) The Gαi1 α5 helix tilt changed due to the outward movement of TMH5 in CB2 R*. 2) A 25° clockwise rotation of Gαi1β1γ2 underneath CB2 R* occurred, with rotation ceasing when Pro-139 (IC-2 loop) anchors in a hydrophobic pocket on Gαi1 (Val-34, Leu-194, Phe-196, Phe-336, Thr-340, Ile-343, and Ile-344). In this complex, all three experimentally identified cross-links can occur. These findings should be relevant for other class A G protein-coupled receptors that couple to Gi proteins. PMID:24855641

Microglial Fc Receptors Mediate Physiological Changes Resulting From Antibody Cross-Linking of Myelin Oligodendrocyte Glycoprotein

PubMed Central

Marta, Cecilia B.; Bansal, Rashmi; Pfeiffer, Steven E.

2009-01-01

Antibodies to myelin oligodendrocyte glycoprotein (MOG) have been implicated in Multiple Sclerosis demyelination through activation of complement and/or macrophage-effector processes. We presented a novel mechanism, whereby MOG on oligodendrocytes, when cross-linked with anti-MOG and secondary antibody resulted in its repartitioning into lipid rafts, and changes in protein phosphorylation and morphology. Here, we show that similar events occur when anti-MOG is cross-linked with Fc receptors (FcRs) present on microglia but not with complement. These results indicate that FcRs are endogenous antigen/antibody cross-linkers in vitro, suggesting that FcRs could be physiologically relevant in vivo and possible targets for therapy in Multiple Sclerosis. PMID:18406472

Systematic Review of the Relation Between Intestinal Microbiota and Toll-Like Receptors in the Metabolic Syndrome: What Do We Know So Far?

PubMed

Portela-Cidade, José Pedro; Borges-Canha, Marta; Leite-Moreira, Adelino Ferreira; Pimentel-Nunes, Pedro

2015-01-01

Metabolic syndrome is an emerging problem in developed countries and presents itself as a potential threat worldwide. The role of diabetes, dyslipidaemia and hepatic steatosis as pivotal components of the metabolic syndrome is well known. However, their common persistent chronic inflammation and its potential cause still elude. This systematic review aims to present evidence of the mechanisms that link the intestinal microbioma, innate immunity and metabolic syndrome. A comprehensive research was made using PubMed database and 35 articles were selected. We found that metabolic syndrome is associated to increased levels of innate immunity receptors, namely, Toll-like receptors, both in intestine and systemically and its polymorphisms may change the risk of metabolic syndrome development. Microbioma dysbiosis is also present in metabolic syndrome, with lower prevalence of Bacteroidetes and increased prevalence of Firmicutes populations. The data suggest that the link between intestinal microbiota and Toll-like receptors can negatively endanger the metabolic homeostasis. Current evidence suggests that innate immunity and intestinal microbiota may be the hidden link in the metabolic syndrome development mechanisms. In the near future, this can be the key in the development of new prophylactic and therapeutic strategies to treat metabolic syndrome patients.

Receptors useful for gas phase chemical sensing

DOEpatents

Jaworski, Justyn W; Lee, Seung-Wuk; Majumdar, Arunava; Raorane, Digvijay A

2015-02-17

The invention provides for a receptor, capable of binding to a target molecule, linked to a hygroscopic polymer or hydrogel; and the use of this receptor in a device for detecting the target molecule in a gaseous and/or liquid phase. The invention also provides for a method for detecting the presence of a target molecule in the gas phase using the device. In particular, the receptor can be a peptide capable of binding a 2,4,6-trinitrotoluene (TNT) or 2,4,-dinitrotoluene (DNT).

Serotonin receptors influencing cell proliferation in the jejunal crypt epithelium and in colonic adenocarcinomas.

PubMed

Tutton, P J; Barkla, D H

1986-01-01

Serotonin has previously been shown to stimulate cell proliferation in the jejunal crypt epithelium and in colonic tumours. The original classification of serotonin receptors into D and M groups was not conductive to the understanding of these observations. The more recent classification of serotonin receptors into 5HT1 and 5HT2 groups is considered in this report. On the balance of evidence it appears that similar receptors mediate the response to serotonin in the two tissues under consideration and that these receptors resemble those of the 5HT1 group. Such receptors are usually positively linked to adenylate cyclase.

Low Striatal Dopamine D2-type Receptor Availability is Linked to Simulated Drug Choice in Methamphetamine Users.

PubMed

Moeller, Scott J; Okita, Kyoji; Robertson, Chelsea L; Ballard, Michael E; Konova, Anna B; Goldstein, Rita Z; Mandelkern, Mark A; London, Edythe D

2018-03-01

Individuals with drug use disorders seek drugs over other rewarding activities, and exhibit neurochemical deficits related to dopamine, which is involved in value-based learning and decision-making. Thus, a dopaminergic disturbance may underpin drug-biased choice in addiction. Classical drug-choice assessments, which offer drug-consumption opportunities, are inappropriate for addicted individuals seeking treatment or abstaining. Fifteen recently abstinent methamphetamine users and 15 healthy controls completed two laboratory paradigms of 'simulated' drug choice (choice for drug-related vs affectively pleasant, unpleasant, and neutral images), and underwent positron emission tomography measurements of dopamine D2-type receptor availability, indicated by binding potential (BP ND ) for [ 18 F]fallypride. Thirteen of the methamphetamine users and 10 controls also underwent [ 11 C]NNC112 PET scans to measure dopamine D1-type receptor availability. Group analyses showed that, compared with controls, methamphetamine users chose to view more methamphetamine-related images on one task, with a similar trend on the second task. Regression analyses showed that, on both tasks, the more methamphetamine users chose to view methamphetamine images, specifically vs pleasant images (the most frequently chosen images across all participants), the lower was their D2-type BP ND in the lateral orbitofrontal cortex, an important region in value-based choice. No associations were observed with D2-type BP ND in striatal regions, or with D1-type BP ND in any region. These results identify a neurochemical correlate for a laboratory drug-seeking paradigm that can be administered to treatment-seeking and abstaining drug-addicted individuals. More broadly, these results refine the central hypothesis that dopamine-system deficits contribute to drug-biased decision-making in addiction, here showing a role for the orbitofrontal cortex.

Altered trafficking and unfolded protein response induction as a result of M3 muscarinic receptor impaired N-glycosylation.

PubMed

Romero-Fernandez, Wilber; Borroto-Escuela, Dasiel O; Alea, Mileidys Perez; Garcia-Mesa, Yoelvis; Garriga, Pere

2011-12-01

The human M(3) muscarinic acetylcholine receptor is present in both the central and peripheral nervous system, and it is involved in the pathophysiology of several neurodegenerative and autoimmune diseases. We suggested a possible N-glycosylation map for the M(3) muscarinic receptor expressed in COS-7 cells. Here, we examined the role that N-linked glycans play in the folding and in the cell surface trafficking of this receptor. The five potential asparagine-linked glycosylation sites in the muscarinic receptor were mutated and transiently expressed in COS-7 cells. The elimination of N-glycan attachment sites did not affect the cellular expression levels of the receptor. However, proper receptor localization to the plasma membrane was affected as suggested by reduced [(3)H]-N-methylscopolamine binding. Confocal microscopy confirmed this observation and showed that the nonglycosylated receptor was primarily localized in the intracellular compartments. The mutant variant showed an increase in phosphorylation of the α-subunit of eukaryote initiation factor 2, and other well-known endoplasmic reticulum stress markers of the unfolded protein response pathway, which further supports the proposal of the improper intracellular accumulation of the nonglycosylated receptor. The receptor devoid of glycans showed more susceptibility to events that culminate in apoptosis reducing cell viability. Our findings suggest up-regulation of pro-apoptotic Bax protein, down-regulation of anti-apoptotic Bcl-2, and cleavage of caspase-3 effectors. Collectively, our data provide experimental evidence of the critical role that N-glycan chains play in determining muscarinic receptor distribution, localization, as well as cell integrity. © The Author 2011. Published by Oxford University Press. All rights reserved.

Biological substantiation of antipsychotic-associated pneumonia: Systematic literature review and computational analyses

PubMed Central

2017-01-01

Introduction Antipsychotic (AP) safety has been widely investigated. However, mechanisms underlying AP-associated pneumonia are not well-defined. Aim The aim of this study was to investigate the known mechanisms of AP-associated pneumonia through a systematic literature review, confirm these mechanisms using an independent data source on drug targets and attempt to identify novel AP drug targets potentially linked to pneumonia. Methods A search was conducted in Medline and Web of Science to identify studies exploring the association between pneumonia and antipsychotic use, from which information on hypothesized mechanism of action was extracted. All studies had to be in English and had to concern AP use as an intervention in persons of any age and for any indication, provided that the outcome was pneumonia. Information on the study design, population, exposure, outcome, risk estimate and mechanism of action was tabulated. Public repositories of pharmacology and drug safety data were used to identify the receptor binding profile and AP safety events. Cytoscape was then used to map biological pathways that could link AP targets and off-targets to pneumonia. Results The literature search yielded 200 articles; 41 were included in the review. Thirty studies reported a hypothesized mechanism of action, most commonly activation/inhibition of cholinergic, histaminergic and dopaminergic receptors. In vitro pharmacology data confirmed receptor affinities identified in the literature review. Two targets, thromboxane A2 receptor (TBXA2R) and platelet activating factor receptor (PTAFR) were found to be novel AP target receptors potentially associated with pneumonia. Biological pathways constructed using Cytoscape identified plausible biological links potentially leading to pneumonia downstream of TBXA2R and PTAFR. Conclusion Innovative approaches for biological substantiation of drug-adverse event associations may strengthen evidence on drug safety profiles and help to tailor pharmacological therapies to patient risk factors. PMID:29077727

Binding-, intracellular transport-, and biosynthesis-defective mutants of vasopressin type 2 receptor in patients with X-linked nephrogenic diabetes insipidus.

PubMed Central

Tsukaguchi, H; Matsubara, H; Taketani, S; Mori, Y; Seido, T; Inada, M

1995-01-01

Nephrogenic diabetes insipidus (NDI) is most often an X-linked disorder in which urine is not concentrated due to renal resistance to arginine vasopressin. We recently identified four vasopressin type 2 receptor gene mutations in unrelated X-linked NDI families, including R143P, delta V278, R202C, and 804insG. All these mutations reduced ligand binding activity to < 10% of the normal without affecting mRNA accumulation. To elucidate whether the receptors are expressed on the cell surface, we analyzed biosynthesis and localization of tagged or untagged receptors stably expressed in Chinese hamster ovary (CHO) cells, using two antibodies directed against distinct termini. Whole-cell and surface labeling studies revealed that the R202C clone had both surface-localized (50-55 kD) and intracellular proteins (40 and 75 kD), similar to the wild-type AVPR2 clone, whereas the R143P and delta V278 clones lacked the surface receptors, despite relatively increased intracellular components. The 804insG mutant cell produced no proteins despite an adequate mRNA level. Immunofluorescence staining confirmed that the R202C mutant reaches the cell surface, whereas the R143P and delta V278 mutants are retained within the cytoplasmic compartment. Thus, R202C, R143P/delta V278, and 804insG result in three distinct phenotypes, that is, a simple binding impairment at the cell surface, blocked intracellular transport, and ineffective biosynthesis or/and accelerated degradation of the receptor, respectively, and therefore are responsible for NDI. This phenotypic classification will help understanding of molecular pathophysiology of this disorder. Images PMID:7560098

Biological substantiation of antipsychotic-associated pneumonia: Systematic literature review and computational analyses.

PubMed

Sultana, Janet; Calabró, Marco; Garcia-Serna, Ricard; Ferrajolo, Carmen; Crisafulli, Concetta; Mestres, Jordi; Trifirò', Gianluca

2017-01-01

Antipsychotic (AP) safety has been widely investigated. However, mechanisms underlying AP-associated pneumonia are not well-defined. The aim of this study was to investigate the known mechanisms of AP-associated pneumonia through a systematic literature review, confirm these mechanisms using an independent data source on drug targets and attempt to identify novel AP drug targets potentially linked to pneumonia. A search was conducted in Medline and Web of Science to identify studies exploring the association between pneumonia and antipsychotic use, from which information on hypothesized mechanism of action was extracted. All studies had to be in English and had to concern AP use as an intervention in persons of any age and for any indication, provided that the outcome was pneumonia. Information on the study design, population, exposure, outcome, risk estimate and mechanism of action was tabulated. Public repositories of pharmacology and drug safety data were used to identify the receptor binding profile and AP safety events. Cytoscape was then used to map biological pathways that could link AP targets and off-targets to pneumonia. The literature search yielded 200 articles; 41 were included in the review. Thirty studies reported a hypothesized mechanism of action, most commonly activation/inhibition of cholinergic, histaminergic and dopaminergic receptors. In vitro pharmacology data confirmed receptor affinities identified in the literature review. Two targets, thromboxane A2 receptor (TBXA2R) and platelet activating factor receptor (PTAFR) were found to be novel AP target receptors potentially associated with pneumonia. Biological pathways constructed using Cytoscape identified plausible biological links potentially leading to pneumonia downstream of TBXA2R and PTAFR. Innovative approaches for biological substantiation of drug-adverse event associations may strengthen evidence on drug safety profiles and help to tailor pharmacological therapies to patient risk factors.

Novel codrugs with GABAergic activity for dopamine delivery in the brain.

PubMed

Denora, Nunzio; Cassano, Tommaso; Laquintana, Valentino; Lopalco, Antonio; Trapani, Adriana; Cimmino, Concetta Stefania; Laconca, Leonardo; Giuffrida, Andrea; Trapani, Giuseppe

2012-11-01

This study investigates the use of codrugs of the GABAergic agent 2-phenyl-imidazo[1,2-a]pyridinacetamide and dopamine (DA) or ethyl ester L-Dopa (LD) as a strategy to deliver DA and simultaneously activate GABA-receptors in the brain. For this purpose, both DA and LD ethyl ester were linked by carbamate bond to imidazo[1,2-a]pyridine acetamide moieties to yield two DA- and two LD-imidazopyridine derivatives. These compounds were evaluated in vitro to assess their stability, binding affinities and cell membrane transport, and in vivo to assess their bio-availability via microdialysis studies. The two DA derivatives were adequately stable in buffered solution, but underwent cleavage in diluted human serum. By contrast, the LD derivatives were unstable in buffered solution. Receptor binding studies showed that the DA-imidazopyridine carbamates had binding affinity for benzodiazepine receptors in the nanomolar range. Brain microdialysis experiments indicated that intraperitoneal administration of the DA derivatives sustained DA levels in rat striatum over a 4-h period. These results suggest that DA-imidazopyridine carbamates are new DA codrugs with potential application for DA replacement therapy. Copyright © 2012 Elsevier B.V. All rights reserved.

A modern ionotropic glutamate receptor with a K(+) selectivity signature sequence.

PubMed

Janovjak, H; Sandoz, G; Isacoff, E Y

2011-01-01

Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system and gates non-selective cation channels. The origins of glutamate receptors are not well understood as they differ structurally and functionally from simple bacterial ligand-gated ion channels. Here we report the discovery of an ionotropic glutamate receptor that combines the typical eukaryotic domain architecture with the 'TXVGYG' signature sequence of the selectivity filter found in K(+) channels. This receptor exhibits functional properties intermediate between bacterial and eukaryotic glutamate-gated ion channels, suggesting a link in the evolution of ionotropic glutamate receptors.

The metabolic impact of β-hydroxybutyrate on neurotransmission: Reduced glycolysis mediates changes in calcium responses and KATP channel receptor sensitivity.

PubMed

Lund, Trine M; Ploug, Kenneth B; Iversen, Anne; Jensen, Anders A; Jansen-Olesen, Inger

2015-03-01

Glucose is the main energy substrate for neurons, and ketone bodies are known to be alternative substrates. However, the capacity of ketone bodies to support different neuronal functions is still unknown. Thus, a change in energy substrate from glucose alone to a combination of glucose and β-hydroxybutyrate might change neuronal function as there is a known coupling between metabolism and neurotransmission. The purpose of this study was to shed light on the effects of the ketone body β-hydroxybutyrate on glycolysis and neurotransmission in cultured murine glutamatergic neurons. Previous studies have shown an effect of β-hydroxybutyrate on glucose metabolism, and the present study further specified this by showing attenuation of glycolysis when β-hydroxybutyrate was present in these neurons. In addition, the NMDA receptor-induced calcium responses in the neurons were diminished in the presence of β-hydroxybutyrate, whereas a direct effect of the ketone body on transmitter release was absent. However, the presence of β-hydroxybutyrate augmented transmitter release induced by the KATP channel blocker glibenclamide, thus giving an indirect indication of the involvement of KATP channels in the effects of ketone bodies on transmitter release. Energy metabolism and neurotransmission are linked and involve ATP-sensitive potassium (KATP ) channels. However, it is still unclear how and to what degree available energy substrate affects this link. We investigated the effect of changing energy substrate from only glucose to a combination of glucose and R-β-hydroxybutyrate in cultured neurons. Using the latter combination, glycolysis was diminished, NMDA receptor-induced calcium responses were lower, and the KATP channel blocker glibenclamide caused a higher transmitter release. © 2014 International Society for Neurochemistry.

Ghrelin receptor regulates adipose tissue inflammation in aging

USDA-ARS?s Scientific Manuscript database

Aging is commonly associated with low-grade adipose inflammation, which is closely linked to insulin resistance. Ghrelin is the only circulating orexigenic hormone which is known to increase obesity and insulin resistance. We previously reported that the expression of the ghrelin receptor, growth ho...

Toward an understanding of agonist binding to human Orexin-1 and Orexin-2 receptors with G-protein-coupled receptor modeling and site-directed mutagenesis.

PubMed

Heifetz, Alexander; Barker, Oliver; Morris, G Benjamin; Law, Richard J; Slack, Mark; Biggin, Philip C

2013-11-19

The class A G-protein-coupled receptors (GPCRs) Orexin-1 (OX1) and Orexin-2 (OX2) are located predominantly in the brain and are linked to a range of different physiological functions, including the control of feeding, energy metabolism, modulation of neuro-endocrine function, and regulation of the sleep-wake cycle. The natural agonists for OX1 and OX2 are two neuropeptides, Orexin-A and Orexin-B, which have activity at both receptors. Site-directed mutagenesis (SDM) has been reported on both the receptors and the peptides and has provided important insight into key features responsible for agonist activity. However, the structural interpretation of how these data are linked together is still lacking. In this work, we produced and used SDM data, homology modeling followed by MD simulation, and ensemble-flexible docking to generate binding poses of the Orexin peptides in the OX receptors to rationalize the SDM data. We also developed a protein pairwise similarity comparing method (ProS) and a GPCR-likeness assessment score (GLAS) to explore the structural data generated within a molecular dynamics simulation and to help distinguish between different GPCR substates. The results demonstrate how these newly developed methods of structural assessment for GPCRs can be used to provide a working model of neuropeptide-Orexin receptor interaction.

Chemical crosslinking and mass spectrometry studies of the structure and dynamics of membrane proteins and receptors.

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

Haskins, William E.; Leavell, Michael D.; Lane, Pamela

2005-03-01

Membrane proteins make up a diverse and important subset of proteins for which structural information is limited. In this study, chemical cross-linking and mass spectrometry were used to explore the structure of the G-protein-coupled photoreceptor bovine rhodopsin in the dark-state conformation. All experiments were performed in rod outer segment membranes using amino acid 'handles' in the native protein sequence and thus minimizing perturbations to the native protein structure. Cysteine and lysine residues were covalently cross-linked using commercially available reagents with a range of linker arm lengths. Following chemical digestion of cross-linked protein, cross-linked peptides were identified by accurate mass measurementmore » using liquid chromatography-fourier transform mass spectrometry and an automated data analysis pipeline. Assignments were confirmed and, if necessary, resolved, by tandem MS. The relative reactivity of lysine residues participating in cross-links was evaluated by labeling with NHS-esters. A distinct pattern of cross-link formation within the C-terminal domain, and between loop I and the C-terminal domain, emerged. Theoretical distances based on cross-linking were compared to inter-atomic distances determined from the energy-minimized X-ray crystal structure and Monte Carlo conformational search procedures. In general, the observed cross-links can be explained by re-positioning participating side-chains without significantly altering backbone structure. One exception, between C3 16 and K325, requires backbone motion to bring the reactive atoms into sufficient proximity for cross-linking. Evidence from other studies suggests that residues around K325 for a region of high backbone mobility. These findings show that cross-linking studies can provide insight into the structural dynamics of membrane proteins in their native environment.« less

Reversal of inhibition of putative dopaminergic neurons of the ventral tegmental area: Interaction of GABAB and D2 receptors

PubMed Central

Nimitvilai, Sudarat; Arora, Devinder S.; McElvain, Maureen A.; Brodie, Mark S.

2012-01-01

Neurons of the ventral tegmental area (VTA) are critical in the rewarding and reinforcing properties of drugs of abuse. Desensitization of VTA neurons to moderate extracellular concentrations of dopamine (DA) is dependent on protein kinase C (PKC) and intracellular calcium levels. This desensitization is called DA inhibition reversal (DIR), as it requires concurrent activation of D2 and D1-like receptors; activation of D2 receptors alone does not result in desensitization. Activation of other G-protein linked receptors can substitute for D1 activation. Like D2 receptors, GABAB receptors in the VTA are coupled to G-protein-linked potassium channels. In the present study, we examined interactions between a GABAB agonist, baclofen, and dopamine agonists, dopamine and quinpirole, to determine whether there was some interaction in the processes of desensitization of GABAB and D2 responses. Long-duration administration of baclofen alone produced reversal of the baclofen-induced inhibition indicative of desensitization, and this desensitization persisted for at least 60 min after baclofen washout. Desensitization to baclofen was dependent on protein kinase C. Dopamine inhibition was reduced for 30 min after baclofen-induced desensitization and conversely, the magnitude of baclofen inhibition was reduced for 30 min by long-duration application of dopamine, but not quinpirole. These results indicate that D2 and GABAB receptors share some protein kinase C-dependent mechanisms of receptor desensitization. PMID:22986166

Adverse Effects of GLP-1 Receptor Agonists

PubMed Central

Filippatos, Theodosios D.; Panagiotopoulou, Thalia V.; Elisaf, Moses S.

2014-01-01

Glucagon-like peptide-1 (GLP-1) receptor agonists are a class of injective anti-diabetic drugs that improve glycemic control and many other atherosclerosis-related parameters in patients with type 2 diabetes (T2D). However, the use of this relatively new class of drugs may be associated with certain adverse effects. Concerns have been expressed regarding the effects of these drugs on pancreatic and thyroid tissue, since animal studies and analyses of drug databases indicate an association of GLP-1 receptor agonists with pancreatitis, pancreatic cancer, and thyroid cancer. However, several meta-analyses failed to confirm a cause-effect relation between GLP-1 receptor agonists and the development of these adverse effects. One benefit of GLP-1 receptor agonists is that they do not cause hypoglycemia when combined with metformin or thiazolidinediones, but the dose of concomitant sulphonylurea or insulin may have to be decreased to reduce the risk of hypoglycemic episodes. On the other hand, several case reports have linked the use of these drugs, mainly exenatide, with the occurrence of acute kidney injury, primarily through hemodynamic derangement due to nausea, vomiting, and diarrhea. The most common symptoms associated with the use of GLP-1 receptor agonists are gastrointestinal symptoms, mainly nausea. Other common adverse effects include injection site reactions, headache, and nasopharyngitis, but these effects do not usually result in discontinuation of the drug. Current evidence shows that GLP-1 receptor agonists have no negative effects on the cardiovascular risk of patients with T2D. Thus, GLP-1 receptor agonists appear to have a favorable safety profile, but ongoing trials will further assess their cardiovascular effects. The aim of this review is to analyze critically the available data regarding adverse events of GLP-1 receptor agonists in different anatomic systems published in Pubmed and Scopus. Whenever possible, certain differences between GLP-1 receptor agonists are described. The review also provides the reader with structured data that compare the rates of the most common adverse effects for each of the various GLP-1 receptor agonists. PMID:26177483

Sex differences in stress-related receptors: ″micro″ differences with ″macro″ implications for mood and anxiety disorders

PubMed Central

2013-01-01

Stress-related psychiatric disorders, such as unipolar depression and post-traumatic stress disorder (PTSD), occur more frequently in women than in men. Emerging research suggests that sex differences in receptors for the stress hormones, corticotropin releasing factor (CRF) and glucocorticoids, contribute to this disparity. For example, sex differences in CRF receptor binding in the amygdala of rats may predispose females to greater anxiety following stressful events. Additionally, sex differences in CRF receptor signaling and trafficking in the locus coeruleus arousal center combine to make females more sensitive to low levels of CRF, and less adaptable to high levels. These receptor differences in females could lead to hyperarousal, a dysregulated state associated with symptoms of depression and PTSD. Similar to the sex differences observed in CRF receptors, sex differences in glucocorticoid receptor (GR) function also appear to make females more susceptible to dysregulation after a stressful event. Following hypothalamic pituitary adrenal axis activation, GRs are critical to the negative feedback process that inhibits additional glucocorticoid release. Compared to males, female rats have fewer GRs and impaired GR translocation following chronic adolescent stress, effects linked to slower glucocorticoid negative feedback. Thus, under conditions of chronic stress, attenuated negative feedback in females would result in hypercortisolemia, an endocrine state thought to cause depression. Together, these studies suggest that sex differences in stress-related receptors shift females more easily into a dysregulated state of stress reactivity, linked to the development of mood and anxiety disorders. The implications of these receptor sex differences for the development of novel pharmacotherapies are also discussed. PMID:23336736

Bile acid receptors link nutrient sensing to metabolic regulation

PubMed Central

Li, Jibiao; Li, Tiangang

2017-01-01

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

Diminished hepatic growth hormone receptor binding in sex-linked dwarf broiler and leghorn chickens.

PubMed

Leung, F C; Styles, W J; Rosenblum, C I; Lilburn, M S; Marsh, J A

1987-02-01

Hepatic growth hormone (GH) receptor binding was compared in normal and sex-linked dwarfs (SLD) from both Hubbard and Cornell strain chickens. At 6, 8, and 20 weeks of age, hepatic GH receptor binding in the Hubbard SLD chickens was significantly lower than that of normal fast-growing birds. At 20 weeks of age, only 2 of 22 SLD chickens in the Hubbard broiler strain showed positive binding at a high enough level to allow for Scatchard analysis. The affinity constants and binding capacities of these two SLD chickens were numerically (but not significantly) lower than those of the normal fast-growing birds. We further examined hepatic GH receptor binding in two closely related White Leghorn strains of chickens that have been maintained as closed breeding populations for many years. We observed no detectable hepatic GH binding in the Cornell SLD chickens (N = 20), as compared to the normal-growing control strain (K strain). In both SLD strains, pretreatment with 4 M MgCl2 did not enhance GH binding, suggesting that there was no endogenous GH binding to the receptor. Based on these data, we suggest that the lack, or greatly reduced number, of GH receptors may be a major contributing factor to the dwarfism observed in these strains.

SRC-1 regulates blood pressure and aortic stiffness in female mice

USDA-ARS?s Scientific Manuscript database

Framingham Heart Study suggests that dysfunction of steroid receptor coactivator-1 may be involved in the development of hypertension. However, there is no functional evidence linking steroid receptor coactivator-1 to the regulation of blood pressure. We used immunohistochemistry to map the expressi...

delta 9-(16 alpha-/sup 125/I)iodo-19-nortestosterone: a gamma-emitting photoaffinity label for the progesterone receptor

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

Lamb, D.J.; Bullock, D.W.; Hoyte, R.M.

1988-05-01

We have synthesized 16 alpha-iodo-4,9-estradien-17 beta-ol-3-one (delta 9-16 alpha-iodo-19-nortestosterone (delta 9-INT)) labeled with 125I (delta 9-(16 alpha-125I)INT) to provide a new gamma-emitting photoaffinity ligand for the progesterone receptor that has many advantages over the currently available (3H)R5020. We have characterized the interaction of delta 9-(16 alpha-125I)INT with the rabbit uterine progesterone receptor and have demonstrated the usefulness of this compound for studies of receptor structure. The binding of 2 nM (3H)progesterone to receptor in rabbit uterine cytosol was specifically competed for by 19-nortestosterone, 16 alpha-iodo-19-nortestosterone, and delta 9-INT. Scatchard analysis demonstrated that delta 9-(16 alpha-125I)INT and (3H)progesterone estimated the samemore » number of binding sites in rabbit uterine cytosol, with a Kd for delta 9-(16 alpha-125I)INT of about 2.7 nM. The binding of delta 9-(16 alpha-125I)INT was inhibited by both progesterone and R5020, whereas testosterone, estradiol, and 5 alpha-dihydrotestosterone were ineffective. In cytosol, delta 9-(16 alpha-125I)INT covalently labeled the same mol wt receptor forms as (3H)R5020. Although the efficiency of cross-linking was similar for (3H)R5020 (3%) and delta 9-(16 alpha-125I)INT (4%), the radioactivity was 10-fold greater due to the higher specific activity of delta 9-(16 alpha-125I)INT and the lack of sample quench. The use of delta 9-(16 alpha-125I)INT greatly increases the sensitivity and efficiency of the photoaffinity labeling technique; it will provide a valuable tool for further studies of the progesterone receptor, allowing the detection of receptor in dilute cytosol after gel electrophoresis under denaturing conditions.« less

The influences of metabotropic receptor activation on cellular signaling and synaptic function in amacrine cells.

PubMed

Gleason, Evanna

2012-01-01

Amacrine cells receive glutamatergic input from bipolar cells and GABAergic, glycinergic, cholinergic, and dopaminergic input from other amacrine cells. Glutamate, GABA, glycine, and acetylcholine (ACh) interact with ionotropic receptors and it is these interactions that form much of the functional circuitry in the inner retina. However, glutamate, GABA, ACh, and dopamine also activate metabotropic receptors linked to second messenger pathways that have the potential to modify the function of individual cells as well as retinal circuitry. Here, the physiological effects of activating dopamine receptors, metabotropic glutamate receptors, GABAB receptors, and muscarinic ACh receptors on amacrine cells will be discussed. The retina also expresses metabotropic receptors and the biochemical machinery associated with the synthesis and degradation of endocannabinoids and sphingosine-1-phosphate (S1P). The effects of activating cannabinoid receptors and S1P receptors on amacrine cell function will also be addressed. Copyright © Cambridge University Press, 2012

The lactate receptor, G-protein-coupled receptor 81/hydroxycarboxylic acid receptor 1: Expression and action in brain.

PubMed

Morland, Cecilie; Lauritzen, Knut Husø; Puchades, Maja; Holm-Hansen, Signe; Andersson, Krister; Gjedde, Albert; Attramadal, Håvard; Storm-Mathisen, Jon; Bergersen, Linda Hildegard

2015-07-01

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 the cerebral neocortex and the hippocampus, where it can be stimulated by physiological concentrations of lactate and by the HCAR1 agonist 3,5-dihydroxybenzoate to reduce cAMP levels. Cerebral HCAR1 is concentrated on the postsynaptic membranes of excitatory synapses and also is enriched at the blood-brain barrier. In synaptic spines and in adipocytes, HCAR1 immunoreactivity is also located on subplasmalemmal vesicular organelles, suggesting trafficking to and from the plasma membrane. Through activation of HCAR1, lactate can act as a volume transmitter that links neuronal activity, cerebral blood flow, 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, and schizophrenia and in the deposition of phosphorylated tau protein in Alzheimer's disease. HCAR1 could serve to ameliorate these conditions and might also act through downstream mechanisms other than cAMP. Lactate exits cells through monocarboxylate transporters in an equilibrating manner and through astrocyte anion channels activated by depolarization. In addition to locally produced lactate, lactate produced by exercising muscle as well as exogenous HCAR1 agonists, e.g., from fruits and berries, might activate the receptor on cerebral blood vessels and brain cells. © 2015 Wiley Periodicals, Inc.

Gene transfer mediated by alpha2-macroglobulin.

PubMed Central

Schneider, H; Huse, K; Birkenmeier, G; Otto, A; Scholz, G H

1996-01-01

alpha2-Macroglobulin covalently linked to poly(L)-lysine can be used as a vehicle for receptor-mediated gene transfer. This modified alpha2-macroglobulin maintains its ability to bind to the alpha2-macroglobulin receptor, and was shown to introduce a luciferase reporter gene plasmid into HepG2 human hepatoma cells in vitro. The alpha2-macroglobulin receptor is a very large and multifunctional cell surface receptor, whose rapid and efficient internalization rate makes it attractive for gene therapy, e.g. for hepatic gene targeting via injection into the portal vein. PMID:8871570

Reversible and Selective Encapsulation of Dextromethorphan and β-Estradiol Using an Asymmetric Molecular Capsule Assembled via the Weak-Link Approach.

PubMed

Mendez-Arroyo, Jose; d'Aquino, Andrea I; Chinen, Alyssa B; Manraj, Yashin D; Mirkin, Chad A

2017-02-01

An allosterically regulated, asymmetric receptor featuring a binding cavity large enough to accommodate three-dimensional pharmaceutical guest molecules as opposed to planar, rigid aromatics, was synthesized via the Weak-Link Approach. This architecture is capable of switching between an expanded, flexible "open" configuration and a collapsed, rigid "closed" one. The structure of the molecular receptor can be completely modulated in situ through the use of simple ionic effectors, which reversibly control the coordination state of the Pt(II) metal hinges to open and close the molecular receptor. The substantial change in binding cavity size and electrostatic charge between the two configurations is used to explore the capture and release of two guest molecules, dextromethorphan and β-estradiol, which are widely found as pollutants in groundwater.

PET imaging of dopamine D2 receptors during chronic cocaine self-administration in monkeys.

PubMed

Nader, Michael A; Morgan, Drake; Gage, H Donald; Nader, Susan H; Calhoun, Tonya L; Buchheimer, Nancy; Ehrenkaufer, Richard; Mach, Robert H

2006-08-01

Dopamine neurotransmission is associated with high susceptibility to cocaine abuse. Positron emission tomography was used in 12 rhesus macaques to determine if dopamine D2 receptor availability was associated with the rate of cocaine reinforcement, and to study changes in brain dopaminergic function during maintenance of and abstinence from cocaine. Baseline D2 receptor availability was negatively correlated with rates of cocaine self-administration. D2 receptor availability decreased by 15-20% within 1 week of initiating self-administration and remained reduced by approximately 20% during 1 year of exposure. Long-term reductions in D2 receptor availability were observed, with decreases persisting for up to 1 year of abstinence in some monkeys. These data provide evidence for a predisposition to self-administer cocaine based on D2 receptor availability, and demonstrate that the brain dopamine system responds rapidly following cocaine exposure. Individual differences in the rate of recovery of D2 receptor function during abstinence were noted.

U.S. Army Aeromedical Research Laboratory Annual Progress Report Fiscal Year 2010

DTIC Science & Technology

2011-03-01

S. (2010). Epidermal growth factor receptor transactivation by the cannabinoid receptor (CB1) and transient receptor potential vanilloid 1 ( TRPV1 ...induced by TRPV1 in human corneal epithelial cells. Proceedings of the Association for Research in Vision and Ophthalmology Annual Meeting, 5899/A94...presented “Novel TRPV1 -linked cell signaling pathways mediating inflammatory responses and wound healing in human corneal epithelial cells” at the Fouth

Adenosine-diphosphate (ADP) receptor antagonists for the prevention of cardiovascular disease in type 2 diabetes mellitus.

PubMed

Valentine, Nyoli; Van de Laar, Floris A; van Driel, Mieke L

2012-11-14

Cardiovascular disease (CVD) is the most prevalent complication of type 2 diabetes with an estimated 65% of people with type 2 diabetes dying from a cause related to atherosclerosis. Adenosine-diphosphate (ADP) receptor antagonists like clopidogrel, ticlopidine, prasugrel and ticagrelor impair platelet aggregation and fibrinogen-mediated platelet cross-linking and may be effective in preventing CVD. To assess the effects of adenosine-diphosphate (ADP) receptor antagonists for the prevention of cardiovascular disease in type 2 diabetes mellitus. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (issue 2, 2011), MEDLINE (until April 2011) and EMBASE (until May 2011). We also performed a manual search, checking references of original articles and pertinent reviews to identify additional studies. Randomised controlled trials comparing an ADP receptor antagonist with another antiplatelet agent or placebo for a minimum of 12 months in patients with diabetes. In particular, we looked for trials assessing clinical cardiovascular outcomes. Two review authors extracted data for studies which fulfilled the inclusion criteria, using standard data extraction templates. We sought additional unpublished information and data from the principal investigators of all included studies. Eight studies with a total of 21,379 patients with diabetes were included. Three included studies investigated ticlopidine compared to aspirin or placebo. Five included studies investigated clopidogrel compared to aspirin or a combination of aspirin and dipyridamole, or compared clopidogrel in combination with aspirin to aspirin alone. All trials included patients with previous CVD except the CHARISMA trial which included patients with multiple risk factors for coronary artery disease. Overall the risk of bias of the trials was low. The mean duration of follow-up ranged from 365 days to 913 days.Data for diabetes patients on all-cause mortality, vascular mortality and myocardial infarction were only available for one trial (355 patients). This trial compared ticlopidine to placebo and did not demonstrate any statistically significant differences for all-cause mortality, vascular mortality or myocardial infarction. Diabetes outcome data for stroke were available in three trials (31% of total diabetes participants). Overall pooling of two (statistically heterogeneous) studies showed no statistically significant reduction in the combination of fatal and non-fatal stroke (359/3194 (11.2%) versus 356/3146 (11.3%), random effects odds ratio (OR) 0.81; 95% confidence interval (CI) 0.44 to 1.49) for ADP receptor antagonists versus other antiplatelet drugs. There were no data available from any of the trials on peripheral vascular disease, health-related quality of life, adverse events specifically for patients with diabetes, or costs. The available evidence for ADP receptor antagonists in patients with diabetes mellitus is limited and most trials do not report outcomes for patients with diabetes separately. Therefore, recommendations for the use of ADP receptor antagonists for the prevention of CVD in patients with diabetes are based on available evidence from trials including patients with and without diabetes. Trials with diabetes patients and subgroup analyses of patients with diabetes in trials with combined populations are needed to provide a more robust evidence base to guide clinical management in patients with diabetes.

Molecular evolution of a chordate specific family of G protein-coupled receptors

PubMed Central

2011-01-01

Background Chordate evolution is a history of innovations that is marked by physical and behavioral specializations, which led to the development of a variety of forms from a single ancestral group. Among other important characteristics, vertebrates obtained a well developed brain, anterior sensory structures, a closed circulatory system and gills or lungs as blood oxygenation systems. The duplication of pre-existing genes had profound evolutionary implications for the developmental complexity in vertebrates, since mutations modifying the function of a duplicated protein can lead to novel functions, improving the evolutionary success. Results We analyzed here the evolution of the GPRC5 family of G protein-coupled receptors by comprehensive similarity searches and found that the receptors are only present in chordates and that the size of the receptor family expanded, likely due to genome duplication events in the early history of vertebrate evolution. We propose that a single GPRC5 receptor coding gene originated in a stem chordate ancestor and gave rise by duplication events to a gene family comprising three receptor types (GPRC5A-C) in vertebrates, and a fourth homologue present only in mammals (GPRC5D). Additional duplications of GPRC5B and GPRC5C sequences occurred in teleost fishes. The finding that the expression patterns of the receptors are evolutionarily conserved indicates an important biological function of these receptors. Moreover, we found that expression of GPRC5B is regulated by vitamin A in vivo, confirming previous findings that linked receptor expression to retinoic acid levels in tumor cell lines and strengthening the link between the receptor expression and the development of a complex nervous system in chordates, known to be dependent on retinoic acid signaling. Conclusions GPRC5 receptors, a class of G protein-coupled receptors with unique sequence characteristics, may represent a molecular novelty that helped non-chordates to become chordates. PMID:21827690

Caffeine increases striatal dopamine D2/D3 receptor availability in the human brain.

PubMed

Volkow, N D; Wang, G-J; Logan, J; Alexoff, D; Fowler, J S; Thanos, P K; Wong, C; Casado, V; Ferre, S; Tomasi, D

2015-04-14

Caffeine, the most widely consumed psychoactive substance in the world, is used to promote wakefulness and enhance alertness. Like other wake-promoting drugs (stimulants and modafinil), caffeine enhances dopamine (DA) signaling in the brain, which it does predominantly by antagonizing adenosine A2A receptors (A2AR). However, it is unclear if caffeine, at the doses consumed by humans, increases DA release or whether it modulates the functions of postsynaptic DA receptors through its interaction with adenosine receptors, which modulate them. We used positron emission tomography and [(11)C]raclopride (DA D2/D3 receptor radioligand sensitive to endogenous DA) to assess if caffeine increased DA release in striatum in 20 healthy controls. Caffeine (300 mg p.o.) significantly increased the availability of D2/D3 receptors in putamen and ventral striatum, but not in caudate, when compared with placebo. In addition, caffeine-induced increases in D2/D3 receptor availability in the ventral striatum were associated with caffeine-induced increases in alertness. Our findings indicate that in the human brain, caffeine, at doses typically consumed, increases the availability of DA D2/D3 receptors, which indicates that caffeine does not increase DA in the striatum for this would have decreased D2/D3 receptor availability. Instead, we interpret our findings to reflect an increase in D2/D3 receptor levels in striatum with caffeine (or changes in affinity). The association between increases in D2/D3 receptor availability in ventral striatum and alertness suggests that caffeine might enhance arousal, in part, by upregulating D2/D3 receptors.

Caffeine increases striatal dopamine D2/D3 receptor availability in the human brain

PubMed Central

Volkow, N D; Wang, G-J; Logan, J; Alexoff, D; Fowler, J S; Thanos, P K; Wong, C; Casado, V; Ferre, S; Tomasi, D

2015-01-01

Caffeine, the most widely consumed psychoactive substance in the world, is used to promote wakefulness and enhance alertness. Like other wake-promoting drugs (stimulants and modafinil), caffeine enhances dopamine (DA) signaling in the brain, which it does predominantly by antagonizing adenosine A2A receptors (A2AR). However, it is unclear if caffeine, at the doses consumed by humans, increases DA release or whether it modulates the functions of postsynaptic DA receptors through its interaction with adenosine receptors, which modulate them. We used positron emission tomography and [11C]raclopride (DA D2/D3 receptor radioligand sensitive to endogenous DA) to assess if caffeine increased DA release in striatum in 20 healthy controls. Caffeine (300 mg p.o.) significantly increased the availability of D2/D3 receptors in putamen and ventral striatum, but not in caudate, when compared with placebo. In addition, caffeine-induced increases in D2/D3 receptor availability in the ventral striatum were associated with caffeine-induced increases in alertness. Our findings indicate that in the human brain, caffeine, at doses typically consumed, increases the availability of DA D2/D3 receptors, which indicates that caffeine does not increase DA in the striatum for this would have decreased D2/D3 receptor availability. Instead, we interpret our findings to reflect an increase in D2/D3 receptor levels in striatum with caffeine (or changes in affinity). The association between increases in D2/D3 receptor availability in ventral striatum and alertness suggests that caffeine might enhance arousal, in part, by upregulating D2/D3 receptors. PMID:25871974

Caffeine increases striatal dopamine D 2/D 3 receptor availability in the human brain

DOE PAGES

Volkow, N. D.; Wang, G. -J.; Logan, J.; ...

2015-04-14

Caffeine, the most widely consumed psychoactive substance in the world, is used to promote wakefulness and enhance alertness. Like other wake-promoting drugs (stimulants and modafinil), caffeine enhances dopamine (DA) signaling in the brain, which it does predominantly by antagonizing adenosine A 2A receptors (A 2AR). However, it is unclear if caffeine, at the doses consumed by humans, increases DA release or whether it modulates the functions of postsynaptic DA receptors through its interaction with adenosine receptors, which modulate them. We used positron emission tomography and [ 11C]raclopride (DA D 2/D 3 receptor radioligand sensitive to endogenous DA) to assess ifmore » caffeine increased DA release in striatum in 20 healthy controls. Caffeine (300mg p.o.) significantly increased the availability of D 2/D 3 receptors in putamen and ventral striatum, but not in caudate, when compared with placebo. In addition, caffeine-induced increases in D 2/D 3 receptor availability in the ventral striatum were associated with caffeine-induced increases in alertness. Our findings indicate that in the human brain, caffeine, at doses typically consumed, increases the availability of DA D 2/D 3 receptors, which indicates that caffeine does not increase DA in the striatum for this would have decreased D 2/D 3 receptor availability. Instead, we interpret our findings to reflect an increase in D 2/D 3 receptor levels in striatum with caffeine (or changes in affinity). Furthermore, the association between increases in D 2/D 3 receptor availability in ventral striatum and alertness suggests that caffeine might enhance arousal, in part, by upregulating D 2/D 3 receptors.« less

Caffeine increases striatal dopamine D 2/D 3 receptor availability in the human brain

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

Volkow, N. D.; Wang, G. -J.; Logan, J.

Caffeine, the most widely consumed psychoactive substance in the world, is used to promote wakefulness and enhance alertness. Like other wake-promoting drugs (stimulants and modafinil), caffeine enhances dopamine (DA) signaling in the brain, which it does predominantly by antagonizing adenosine A 2A receptors (A 2AR). However, it is unclear if caffeine, at the doses consumed by humans, increases DA release or whether it modulates the functions of postsynaptic DA receptors through its interaction with adenosine receptors, which modulate them. We used positron emission tomography and [ 11C]raclopride (DA D 2/D 3 receptor radioligand sensitive to endogenous DA) to assess ifmore » caffeine increased DA release in striatum in 20 healthy controls. Caffeine (300mg p.o.) significantly increased the availability of D 2/D 3 receptors in putamen and ventral striatum, but not in caudate, when compared with placebo. In addition, caffeine-induced increases in D 2/D 3 receptor availability in the ventral striatum were associated with caffeine-induced increases in alertness. Our findings indicate that in the human brain, caffeine, at doses typically consumed, increases the availability of DA D 2/D 3 receptors, which indicates that caffeine does not increase DA in the striatum for this would have decreased D 2/D 3 receptor availability. Instead, we interpret our findings to reflect an increase in D 2/D 3 receptor levels in striatum with caffeine (or changes in affinity). Furthermore, the association between increases in D 2/D 3 receptor availability in ventral striatum and alertness suggests that caffeine might enhance arousal, in part, by upregulating D 2/D 3 receptors.« less

Pharmacological Activity and Clinical Use of PDRN

PubMed Central

Squadrito, Francesco; Bitto, Alessandra; Irrera, Natasha; Pizzino, Gabriele; Pallio, Giovanni; Minutoli, Letteria; Altavilla, Domenica

2017-01-01

PDRN is a proprietary and registered drug that possesses several activities: tissue repairing, anti-ischemic, and anti-inflammatory. These therapeutic properties suggest its use in regenerative medicine and in diabetic foot ulcers. PDRN holds a mixture of deoxyribonucleotides with molecular weights ranging between 50 and 1,500 KDa, it is derived from a controlled purification and sterilization process of Oncorhynchus mykiss (Salmon Trout) or Oncorhynchus keta (Chum Salmon) sperm DNA. The procedure guarantees the absence of active protein and peptides that may cause immune reactions. In vitro and in vivo experiments have suggested that PDRN most relevant mechanism of action is the engagement of adenosine A2A receptors. Besides engaging the A2A receptor, PDRN offers nucleosides and nucleotides for the so called “salvage pathway.” The binding to adenosine A2A receptors is a unique property of PDRN and seems to be linked to DNA origin, molecular weight and manufacturing process. In this context, PDRN represents a new advancement in the pharmacotherapy. In fact adenosine and dipyridamole are non-selective activators of adenosine receptors and they may cause unwanted side effects; while regadenoson, the only other A2A receptor agonist available, has been approved by the FDA as a pharmacological stress agent in myocardial perfusion imaging. Finally, defibrotide, another drug composed by a mixture of oligonucleotides, has different molecular weight, a DNA of different origin and does not share the same wound healing stimulating effects of PDRN. The present review analyses the more relevant experimental and clinical evidences carried out to characterize PDRN therapeutic effects. PMID:28491036

EpitopeViewer: a Java application for the visualization and analysis of immune epitopes in the Immune Epitope Database and Analysis Resource (IEDB).

PubMed

Beaver, John E; Bourne, Philip E; Ponomarenko, Julia V

2007-02-21

Structural information about epitopes, particularly the three-dimensional (3D) structures of antigens in complex with immune receptors, presents a valuable source of data for immunology. This information is available in the Protein Data Bank (PDB) and provided in curated form by the Immune Epitope Database and Analysis Resource (IEDB). With continued growth in these data and the importance in understanding molecular level interactions of immunological interest there is a need for new specialized molecular visualization and analysis tools. The EpitopeViewer is a platform-independent Java application for the visualization of the three-dimensional structure and sequence of epitopes and analyses of their interactions with antigen-specific receptors of the immune system (antibodies, T cell receptors and MHC molecules). The viewer renders both 3D views and two-dimensional plots of intermolecular interactions between the antigen and receptor(s) by reading curated data from the IEDB and/or calculated on-the-fly from atom coordinates from the PDB. The 3D views and associated interactions can be saved for future use and publication. The EpitopeViewer can be accessed from the IEDB Web site http://www.immuneepitope.org through the quick link 'Browse Records by 3D Structure.' The EpitopeViewer is designed and been tested for use by immunologists with little or no training in molecular graphics. The EpitopeViewer can be launched from most popular Web browsers without user intervention. A Java Runtime Environment (RJE) 1.4.2 or higher is required.

GPR30: a seven-transmembrane-spanning estrogen receptor that triggers EGF release.

PubMed

Filardo, Edward J; Thomas, Peter

2005-10-01

Heterotrimeric G proteins and seven-transmembrane-spanning (7TM) receptors are implicated in rapid estrogen signaling. The orphan 7TM receptor GPR30 is linked to estrogen-mediated activation of adenylyl cyclase, release of epidermal growth factor (EGF)-related ligands, and specific estrogen binding. GPR30 acts independently of estrogen receptors, ERalpha and ERbeta, and probably functions as a heptahelical ER. 7TM receptors elicit signals that stimulate second messengers, and convey intracellular signals via EGF receptors. Identification of GPR30 as a Gs-coupled 7TM receptor that triggers release of heparin-binding EGF establishes its role in cell signaling cascades initiated by estrogens, and explains their capacity to activate second messengers and promote EGF-like effects. Thus, estrogen can signal by the same mechanism as various other hormones, through a specific 7TM receptor.

Extrasynaptic GABAA receptors in the crosshairs of hormones and ethanol

PubMed Central

Mody, Istvan

2008-01-01

Gamma-aminobutyric acid (GABA) is the main chemical inhibitory neurotransmitter in the brain. In the central nervous system (CNS) it acts on two distinct types of receptor: an ion channel, i.e., an “ionotropic” receptor permeable to Cl− and HCO3− (GABAA receptors) and a G-protein coupled “metabotropic” receptor that is linked to various effector mechanisms (GABAB receptors). This review will summarize novel developments in the physiology and pharmacology of GABAA receptors (GABAARs), specifically those found outside synapses. The focus will be on a particular combination of GABAAR subunits sensitive to ovarian and adrenal cortical steroid hormone metabolites that are synthesized in the brain (neurosteroids) and to sobriety impairing concentrations of ethanol. These receptors may be the final common pathway for interactions between ethanol and ovarian and stress-related neurosteroids. PMID:17714830

Analysis and functional characterization of sequence variations in ligand binding domain of thyroid hormone receptors in autism spectrum disorder (ASD) patients.

PubMed

Kalikiri, Mahesh Kumar; Mamidala, Madhu Poornima; Rao, Ananth N; Rajesh, Vidya

2017-12-01

Autism spectrum disorder (ASD) is a neuro developmental disorder, reported to be on a rise in the past two decades. Thyroid hormone-T3 plays an important role in early embryonic and central nervous system development. T3 mediates its function by binding to thyroid hormone receptors, TRα and TRβ. Alterations in T3 levels and thyroid receptor mutations have been earlier implicated in neuropsychiatric disorders and have been linked to environmental toxins. Limited reports from earlier studies have shown the effectiveness of T3 treatment with promising results in children with ASD and that the thyroid hormone levels in these children was also normal. This necessitates the need to explore the genetic variations in the components of the thyroid hormone pathway in ASD children. To achieve this objective, we performed genetic analysis of ligand binding domain of THRA and THRB receptor genes in 30 ASD subjects and in age matched controls from India. Our study for the first time reports novel single nucleotide polymorphisms in the THRA and THRB receptor genes of ASD individuals. Autism Res 2017, 10: 1919-1928. ©2017 International Society for Autism Research, Wiley Periodicals, Inc. Thyroid hormone (T3) and thyroid receptors (TRα and TRβ) are the major components of the thyroid hormone pathway. The link between thyroid pathway and neuronal development is proven in clinical medicine. Since the thyroid hormone levels in Autistic children are normal, variations in their receptors needs to be explored. To achieve this objective, changes in THRA and THRB receptor genes was studied in 30 ASD and normal children from India. The impact of some of these mutations on receptor function was also studied. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

A novel T cell receptor single-chain signaling complex mediates antigen-specific T cell activity and tumor control

PubMed Central

Stone, Jennifer D.; Harris, Daniel T.; Soto, Carolina M.; Chervin, Adam S.; Aggen, David H.; Roy, Edward J.; Kranz, David M.

2014-01-01

Adoptive transfer of genetically modified T cells to treat cancer has shown promise in several clinical trials. Two main strategies have been applied to redirect T cells against cancer: 1) introduction of a full-length T cell receptor (TCR) specific for a tumor-associated peptide-MHC, or 2) introduction of a chimeric antigen receptor (CAR), including an antibody fragment specific for a tumor cell surface antigen, linked intracellularly to T cell signaling domains. Each strategy has advantages and disadvantages for clinical applications. Here, we present data on the in vitro and in vivo effectiveness of a single-chain signaling receptor incorporating a TCR variable fragment as the targeting element (referred to as TCR-SCS). This receptor contained a single-chain TCR (Vβ-linker-Vα) from a high-affinity TCR called m33, linked to the intracellular signaling domains of CD28 and CD3ζ. This format avoided mispairing with endogenous TCR chains, and mediated specific T cell activity when expressed in either CD4 or CD8 T cells. TCR-SCS-transduced CD8-negative cells showed an intriguing sensitivity, compared to full-length TCRs, to higher densities of less stable pepMHC targets. T cells that expressed this peptide-specific receptor persisted in vivo, and exhibited polyfunctional responses. Growth of metastatic antigen-positive tumors was significantly inhibited by T cells that expressed this receptor, and tumor cells that escaped were antigen loss variants. TCR-SCS receptors represent an alternative targeting receptor strategy that combines the advantages of single-chain expression, avoidance of TCR chain mispairing, and targeting of intracellular antigens presented in complex with MHC proteins. PMID:25082071

Two classes of receptor specific for sperm-activating peptide III in sand-dollar spermatozoa.

PubMed

Yoshino, K; Suzuki, N

1992-06-15

We characterized receptors specific for sperm-activating peptide III (SAP-III: DSDSAQNLIQ) in spermatozoa of the sand dollar, Clypeaster japonicus, using both binding and cross-linking techniques. Analyses of the data obtained from the equilibrium binding of a radiolabeled SAP-III analogueto C. japonicus spermatozoa, using Klotz, Scatchard and Hill plots, showed the presence of two classes of receptors specific for SAP-III in the spermatozoa. One of the receptors (high-affinity) had a Kd of 3.4 nM and 3.4 x 10(4) binding sites/spermatozoon. The other receptor (low-affinity) had a Kd of 48 nM, with 6.1 x 10(4) binding sites/spermatozoon. The Kd of the high-affinity receptor was comparable to the median effective concentration of the intracellular-pH-increasing activity of SAP-III and that of the low-affinity receptor was comparable to the median effective concentration of the cellular-cGMP-elevating activity of the peptide. In addition, Scatchard and Hill plots of the data suggested the existence of positive cooperativity between the high-affinity members. Similar results were also obtained from a binding experiment using a sperm-membrane fraction prepared from C. japonicus spermatozoa. The incubation of intact spermatozoa or sperm plasma membranes with the radioiodinated SAP-III analogue and a chemical cross-linking reagent, disuccinimidyl suberate, resulted in the radiolabeling of three proteins with molecular masses of 126, 87 and 64 kDa, estimated by SDS/PAGE under reducing conditions.

Nephrogenic diabetes insipidus: an X chromosome-linked dominant inheritance pattern with a vasopressin type 2 receptor gene that is structurally normal.

PubMed Central

Friedman, E; Bale, A E; Carson, E; Boson, W L; Nordenskjöld, M; Ritzén, M; Ferreira, P C; Jammal, A; De Marco, L

1994-01-01

Nephrogenic diabetes insipidus is a rare hereditary disorder, most commonly transmitted in an X chromosome-linked recessive manner and characterized by the lack of renal response to the action of antidiuretic hormone [Arg8]vasopressin. The vasopressin type 2 receptor (V2R) has been suggested to be the gene that causes the disease, and its role in disease pathogenesis is supported by mutations within this gene in affected individuals. Using the PCR, denaturing gradient gel electrophoresis, and direct DNA sequencing, we examined the V2R gene in four unrelated kindreds. In addition, linkage analysis with chromosome Xq28 markers was done in one large Brazilian kindred with an apparent unusual X chromosome-linked dominant inheritance pattern. In one family, a mutation in codon 280, causing a Tyr-->Cys substitution in the sixth transmembrane domain of the receptor, was found. In the other three additional families with nephrogenic diabetes insipidus, the V2R-coding region was normal in sequence. In one large Brazilian kindred displaying an unusual X chromosome-linked dominant mode of inheritance, the disease-related gene was localized to the same region of the X chromosome as the V2R, but no mutations were found, thus raising the possibility that this disease is caused by a gene other than V2R. Images PMID:8078903

Is receptor oligomerization causally linked to activation of the EGF receptor kinase?

NASA Technical Reports Server (NTRS)

Rintoul, D. A.; Spooner, B. S. (Principal Investigator)

1992-01-01

Transduction of a signal from an extracellular peptide hormone to produce an intracellular response is often mediated by a cell surface receptor, which is usually a glycoprotein. The secondary intracellular signal(s) generated after hormone binding to the receptor have been intensively studied. The nature of the primary signal generated by ligand binding to the receptor is understood less well in most cases. The particular case of the epidermal growth factor (EGF) receptor is analyzed, and evidence for or against two dissimilar models of primary signal transduction is reviewed. Evidence for the most widely accepted current model is found to be unconvincing. Evidence for the other model is substantial but indirect; a direct test of this model remains to be done.

Rational Design of Potent Antagonists to the Human Growth Hormone Receptor

NASA Astrophysics Data System (ADS)

Fuh, Germaine; Cunningham, Brian C.; Fukunaga, Rikiro; Nagata, Shigekazu; Goeddel, David V.; Wells, James A.

1992-06-01

A hybrid receptor was constructed that contained the extracellular binding domain of the human growth hormone (hGH) receptor linked to the transmembrane and intracellular domains of the murine granulocyte colony-stimulating factor receptor. Addition of hGH to a myeloid leukemia cell line (FDC-P1) that expressed the hybrid receptor caused proliferation of these cells. The mechanism for signal transduction of the hybrid receptor required dimerization because monoclonal antibodies to the hGH receptor were agonists whereas their monovalent fragments were not. Receptor dimerization occurs sequentially-a receptor binds to site 1 on hGH, and then a second receptor molecule binds to site 2 on hGH. On the basis of this sequential mechanism, which may occur in many other cytokine receptors, inactive hGH analogs were designed that were potent antagonists to hGH-induced cell proliferation. Such antagonists could be useful for treating clinical conditions of hGH excess, such as acromegaly.

Light regulation of the insulin receptor in the retina.

PubMed

Rajala, Raju V S; Anderson, Robert E

2003-10-01

The peptide hormone insulin binds its cognate cell-surface receptors to activate a coordinated biochemical-signaling network and to induce intracellular events. The retina is an integral part of the central nervous system and is known to contain insulin receptors, although their function is unknown. This article, describes recent studies that link the photobleaching of rhodopsin to tyrosine phosphorylation of the insulin receptor and subsequent activation of phosphoinositide 3- kinase (PI3K). We recently found a light-dependent increase in tyrosine phosphorylation of the insulin receptor-beta-subunit (IR beta) and an increase in PI3K enzyme activity in isolated rod outer segments (ROS) and in anti-phosphotyrosine (PY) and anti-IR beta immunoprecipitates of retinal homogenates. The light effect, which was localized to photoreceptor neurons, is independent of insulin secretion. Our results suggest that light induces tyrosine phosphorylation of IR beta in outer-segment membranes, which leads to the binding of p85 through its N-terminal SH2 domain and the generation of PI-3,4,5-P3. We suggest that the physiological role of this process may be to provide neuroprotection of the retina against light damage by activating proteins that protect against stress-induced apoptosis. The studies linking PI3K activation through tyrosine phosphorylation of IR beta now provide physiological relevance for the presence of these receptors in the retina.

Expression of the Grb2-related protein of the lymphoid system in B cell subsets enhances B cell antigen receptor signaling through mitogen-activated protein kinase pathways.

PubMed

Yankee, Thomas M; Solow, Sasha A; Draves, Kevin D; Clark, Edward A

2003-01-01

Adapter proteins play a critical role in regulating signals triggered by Ag receptor cross-linking. These small molecules link receptor proximal events with downstream signaling pathways. In this study, we explore the expression and function of the Grb2-related protein of the lymphoid system (GrpL)/Grb2-related adaptor downstream of Shc adapter protein in human B cells. GrpL is expressed in naive B cells and is down-regulated following B cell Ag receptor ligation. By contrast, germinal center and memory B cells express little or no GrpL. Using human B cell lines, we detected constitutive interactions between GrpL and B cell linker protein, Src homology (SH)2 domain-containing leukocyte protein of 76 kDa, hemopoietic progenitor kinase 1, and c-Cbl. The N-terminal SH3 domain of GrpL binds c-Cbl while the C-terminal SH3 domain binds B cell linker protein and SH2 domain-containing leukocyte protein of 76 kDa. Exogenous expression of GrpL in a GrpL-negative B cell line leads to enhanced Ag receptor-induced extracellular signal-related kinase and p38 mitogen-activated protein kinase phosphorylation. Thus, GrpL expression in human B cell subsets appears to regulate Ag receptor-mediated signaling events.

Nuclear receptor/microRNA circuitry links muscle fiber type to energy metabolism.

PubMed

Gan, Zhenji; Rumsey, John; Hazen, Bethany C; Lai, Ling; Leone, Teresa C; Vega, Rick B; Xie, Hui; Conley, Kevin E; Auwerx, Johan; Smith, Steven R; Olson, Eric N; Kralli, Anastasia; Kelly, Daniel P

2013-06-01

The mechanisms involved in the coordinate regulation of the metabolic and structural programs controlling muscle fitness and endurance are unknown. Recently, the nuclear receptor PPARβ/δ was shown to activate muscle endurance programs in transgenic mice. In contrast, muscle-specific transgenic overexpression of the related nuclear receptor, PPARα, results in reduced capacity for endurance exercise. We took advantage of the divergent actions of PPARβ/δ and PPARα to explore the downstream regulatory circuitry that orchestrates the programs linking muscle fiber type with energy metabolism. Our results indicate that, in addition to the well-established role in transcriptional control of muscle metabolic genes, PPARβ/δ and PPARα participate in programs that exert opposing actions upon the type I fiber program through a distinct muscle microRNA (miRNA) network, dependent on the actions of another nuclear receptor, estrogen-related receptor γ (ERRγ). Gain-of-function and loss-of-function strategies in mice, together with assessment of muscle biopsies from humans, demonstrated that type I muscle fiber proportion is increased via the stimulatory actions of ERRγ on the expression of miR-499 and miR-208b. This nuclear receptor/miRNA regulatory circuit shows promise for the identification of therapeutic targets aimed at maintaining muscle fitness in a variety of chronic disease states, such as obesity, skeletal myopathies, and heart failure.

Is the scavenger receptor MARCO a new immune checkpoint?

PubMed

Arredouani, Mohamed S

2014-11-01

Whereas macrophages use the scavenger receptor MARCO primarily in antimicrobial immunity by interacting with both exogenous and endogenous environments, in dendritic cells (DCs) MARCO is believed to pleiotropically link innate to adaptive immunity. MARCO exerts a significant modulatory effect on TLR-induced DC activation, thus offering novel avenues in cancer immunotherapy.

Gs-coupled GPCR signalling in AgRP neurons triggers sustained increase in food intake.

PubMed

Nakajima, Ken-ichiro; Cui, Zhenzhong; Li, Chia; Meister, Jaroslawna; Cui, Yinghong; Fu, Ou; Smith, Adam S; Jain, Shalini; Lowell, Bradford B; Krashes, Michael J; Wess, Jürgen

2016-01-08

Agouti-related peptide (AgRP) neurons of the hypothalamus play a key role in regulating food intake and body weight, by releasing three different orexigenic molecules: AgRP; GABA; and neuropeptide Y. AgRP neurons express various G protein-coupled receptors (GPCRs) with different coupling properties, including Gs-linked GPCRs. At present, the potential role of Gs-coupled GPCRs in regulating the activity of AgRP neurons remains unknown. Here we show that the activation of Gs-coupled receptors expressed by AgRP neurons leads to a robust and sustained increase in food intake. We also provide detailed mechanistic data linking the stimulation of this class of receptors to the observed feeding phenotype. Moreover, we show that this pathway is clearly distinct from other GPCR signalling cascades that are operative in AgRP neurons. Our data suggest that drugs able to inhibit this signalling pathway may become useful for the treatment of obesity.

Dissecting Nck/Dock signaling pathways in Drosophila visual system.

PubMed

Rao, Yong

2005-01-01

The establishment of neuronal connections during embryonic development requires the precise guidance and targeting of the neuronal growth cone, an expanded cellular structure at the leading tip of a growing axon. The growth cone contains sophisticated signaling systems that allow the rapid communication between guidance receptors and the actin cytoskeleton in generating directed motility. Previous studies demonstrated a specific role for the Nck/Dock SH2/SH3 adapter protein in photoreceptor (R cell) axon guidance and target recognition in the Drosophila visual system, suggesting strongly that Nck/Dock is one of the long-sought missing links between cell surface receptors and the actin cytoskeleton. In this review, I discuss the recent progress on dissecting the Nck/Dock signaling pathways in R-cell growth cones. These studies have identified additional key components of the Nck/Dock signaling pathways for linking the receptor signaling to the remodeling of the actin cytoskeleton in controlling growth-cone motility.

Dissecting Nck/Dock Signaling Pathways in Drosophila Visual System

PubMed Central

2005-01-01

The establishment of neuronal connections during embryonic development requires the precise guidance and targeting of the neuronal growth cone, an expanded cellular structure at the leading tip of a growing axon. The growth cone contains sophisticated signaling systems that allow the rapid communication between guidance receptors and the actin cytoskeleton in generating directed motility. Previous studies demonstrated a specific role for the Nck/Dock SH2/SH3 adapter protein in photoreceptor (R cell) axon guidance and target recognition in the Drosophila visual system, suggesting strongly that Nck/Dock is one of the long-sought missing links between cell surface receptors and the actin cytoskeleton. In this review, I discuss the recent progress on dissecting the Nck/Dock signaling pathways in R-cell growth cones. These studies have identified additional key components of the Nck/Dock signaling pathways for linking the receptor signaling to the remodeling of the actin cytoskeleton in controlling growth-cone motility. PMID:15951852

Ratiometric fluorescent receptors for both Zn2+ and H2PO4(-) ions based on a pyrenyl-linked triazole-modified homooxacalix[3]arene: a potential molecular traffic signal with an R-S latch logic circuit.

PubMed

Ni, Xin-long; Zeng, Xi; Redshaw, Carl; Yamato, Takehiko

2011-07-15

A ratiometric fluorescent receptor with a C(3) symmetric structure based on a pyrene-linked triazole-modified homooxacalix[3]arene (L) was synthesized and characterized. This system exhibited an interesting ratiometric detection signal output for targeting cations and anions through switching the excimer emission of pyrene from the "on-off" to the "off-on" type in neutral solution. (1)H NMR titration results suggested that the Zn(2+) center of receptor L·Zn(2+) provided an excellent pathway of organizing anion binding groups for optimal host-guest interactions. It is thus believed that this receptor has potential application in sensing, detection, and recognition of both Zn(2+) and H(2)PO(4)(-) ions with different optical signals. In addition, the fluorescence emission changes by the inputs of Zn(2+) and H(2)PO(4)(-) ions can be viewed as a combinational R-S latch logic circuit at the molecular level.

N-linked glycosylation of SV2 is required for binding and uptake of botulinum neurotoxin A.

PubMed

Yao, Guorui; Zhang, Sicai; Mahrhold, Stefan; Lam, Kwok-Ho; Stern, Daniel; Bagramyan, Karine; Perry, Kay; Kalkum, Markus; Rummel, Andreas; Dong, Min; Jin, Rongsheng

2016-07-01

Botulinum neurotoxin serotype A1 (BoNT/A1), a licensed drug widely used for medical and cosmetic applications, exerts its action by invading motoneurons. Here we report a 2.0-Å-resolution crystal structure of the BoNT/A1 receptor-binding domain in complex with its neuronal receptor, glycosylated human SV2C. We found that the neuronal tropism of BoNT/A1 requires recognition of both the peptide moiety and an N-linked glycan on SV2. This N-glycan-which is conserved in all SV2 isoforms across vertebrates-is essential for BoNT/A1 binding to neurons and for its potent neurotoxicity. The glycan-binding interface on SV2 is targeted by a human BoNT/A1-neutralizing antibody currently licensed as an antibotulism drug. Our studies reveal a new paradigm of host-pathogen interactions, in which pathogens exploit conserved host post-translational modifications, thereby achieving highly specific receptor binding while also tolerating genetic changes across multiple isoforms of receptors.

N-linked glycosylation of SV2 is required for binding and uptake of botulinum neurotoxin A

PubMed Central

Yao, Guorui; Zhang, Sicai; Mahrhold, Stefan; Lam, Kwok-ho; Stern, Daniel; Bagramyan, Karine; Perry, Kay; Kalkum, Markus; Rummel, Andreas; Dong, Min; Jin, Rongsheng

2016-01-01

Botulinum neurotoxin serotype A1 (BoNT/A1) is one of the most dangerous potential bioterrorism agents, and exerts its action by invading motoneurons. It is also a licensed drug widely used for medical and cosmetic applications. Here we report a 2.0 Å resolution crystal structure of BoNT/A1 receptor-binding domain in complex with its neuronal receptor, the glycosylated human SV2C. We find that the neuronal tropism of BoNT/A1 requires recognition of both the peptide moiety and an N-linked glycan on SV2. This N-glycan—conserved in all SV2 isoforms across vertebrates—is essential for BoNT/A1 binding to neurons and its potent neurotoxicity. The glycan-binding interface on SV2 is targeted by a human BoNT/A1-neutralizing antibody currently licensed as an anti-botulism drug. Our studies reveal a new paradigm of host-pathogen interactions, in which pathogens exploit conserved host post-translational modifications to achieve highly specific receptor binding while also tolerating genetic changes across multiple isoforms of receptors. PMID:27294781

The Oxysterol, 27-Hydroxycholesterol, Links Cholesterol Metabolism to Bone Homeostasis Through Its Actions on the Estrogen and Liver X Receptors

PubMed Central

Nelson, Erik R.; DuSell, Carolyn D.; Wang, Xiaojuan; Howe, Matthew K.; Evans, Glenda; Michalek, Ryan D.; Umetani, Michihisa; Rathmell, Jeffrey C.; Khosla, Sundeep; Gesty-Palmer, Diane

2011-01-01

Osteoporosis and age-related bone loss are important public health concerns. Therefore, there is a high level of interest in the development of medical interventions and lifestyle changes that reduce the incidence of osteoporosis and age-related bone loss. Decreased bone mineral density is associated with high cholesterol, and patients on statins have increased bone mineral densities, strongly implicating cholesterol as a negative regulator of bone homeostasis. In this study, using both molecular and pharmacological approaches, we have been able to demonstrate that the primary cholesterol metabolite, 27-hydroxycholesterol, through its actions on both estrogen receptors and liver X receptors, decreases osteoblast differentiation and enhances osteoclastogenesis, resulting in increased bone resorbtion in mice. Induction of the short heterodimer partner protein by estrogens in osteoblasts can attenuate the liver X receptor-mediated actions of 27-hydroxycholesterol in bone. These data establish a mechanistic link between cholesterol and bone quality, highlight an unexpected target of estrogens in osteoblasts, and define a signaling axis, the therapeutic exploitation of which is likely to yield novel antiosteoporotic drugs. PMID:21933863

VDR, RXR, Coronin-1 and Interferonγ Levels in PBMCs of Type-2 Diabetes Patients: Molecular Link between Diabetes and Tuberculosis.

PubMed

Syal, Kirtimaan; Srinivasan, Anand; Banerjee, Dibyajyoti

2015-07-01

Diabetes and tuberculosis are world's most deadly epidemics. People suffering from diabetes are susceptible to tuberculosis. Molecular link between the two is largely unknown. It is known that Vitamin A receptor (RXR) heterodimerizes with Vitamin D receptor (VDR) and Peroxisome proliferator-activator receptor-γ (PPARγ) to regulate Tryptophan-aspartate containing coat protein (TACO) expression and fatty acid metabolism respectively, so it would be interesting to check the expression of these genes in diabetes mellitus (DM) patients which might explain the susceptibility of diabetics to tuberculosis. In this study, we checked the expression of RXR, VDR, TACO and Interferon-γ (IFNγ) genes in type-2 DM patients for understanding the link between the two diseases. We observed down regulation of RXR gene and corresponding up regulation of TACO gene expression. We have not observed significant change in expression of VDR and IFNγ genes in type-2 DM patients. Repression of RXR gene could hamper VDR-RXR heterodimer formation and thus would up regulate TACO gene expression which may predispose the type-2 DM patients to tuberculosis. Also, decrease in RXR-PPARγ heterodimer could be involved in DM.

Non-T cell activation linker (NTAL) proteolytic cleavage as a terminator of activatory intracellular signals.

PubMed

Arbulo-Echevarria, Mikel M; Muñoz-Miranda, Juan Pedro; Caballero-García, Andrés; Poveda-Díaz, José L; Fernández-Ponce, Cecilia; Durán-Ruiz, M Carmen; Miazek, Arkadiusz; García-Cózar, Francisco; Aguado, Enrique

2016-08-01

Non-T cell activation linker is an adaptor protein that is tyrosine phosphorylated upon cross-linking of immune receptors expressed on B lymphocytes, NK cells, macrophages, basophils, or mast cells, allowing the recruitment of cytosolic mediators for downstream signaling pathways. Fas receptor acts mainly as a death receptor, and when cross-linked with Fas ligand, many proteins are proteolytically cleaved, including several signaling molecules in T and B cells. Fas receptor triggering also interferes with TCR intracellular signals, probably by means of proteolytic cleavage of several adaptor proteins. We have previously found that the adaptor linker for activation of T cells, evolutionarily related to non-T cell activation linker, is cleaved upon proapoptotic stimuli in T lymphocytes and thymocytes, in a tyrosine phosphorylation-dependent fashion. Here, we describe non-T cell activation linker proteolytic cleavage triggered in human B cells and monocytes by Fas cross-linking and staurosporine treatment. Non-T cell activation linker is cleaved, producing an N-terminal fragment of ∼22 kDa, and such cleavage is abrogated in the presence of caspase 8/granzyme B and caspase 3 inhibitors. Moreover, we have identified an aspartic acid residue at which non-T cell activation linker is cleaved, which similar to linker for activation of T cells, this aspartic acid residue is located close to tyrosine and serine residues, suggesting an interdependence of phosphorylation and proteolytic cleavage. Consistently, induction of non-T cell activation linker phosphorylation by pervanadate inhibits its cleavage. Interestingly, the truncated isoform of non-T cell activation linker, generated after cleavage, has a decreased signaling ability when compared with the full-length molecule. Altogether, our results suggest that cleavage of transmembrane adaptors constitutes a general mechanism for signal termination of immune receptors. © Society for Leukocyte Biology.

Deciphering CD30 ligand biology and its role in humoral immunity

PubMed Central

Kennedy, Mary K; Willis, Cynthia R; Armitage, Richard J

2006-01-01

Ligands and receptors in the tumour necrosis factor (TNF) and tumour necrosis factor receptor (TNFR) superfamilies have been the subject of extensive investigation over the past 10–15 years. For certain TNFR family members, such as Fas and CD40, some of the consequences of receptor ligation were predicted before the identification and cloning of their corresponding ligands through in vitro functional studies using agonistic receptor-specific antibodies. For other members of the TNFR family, including CD30, cross-linking the receptor with specific antibodies failed to yield many clues about the functional significance of the relevant ligand–receptor interactions. In many instances, the subsequent availability of TNF family ligands in the form of recombinant protein facilitated the determination of biological consequences of interactions with their relevant receptor in both in vitro and in vivo settings. In the case of CD30 ligand (CD30L; CD153), definition of its biological role remained frustratingly elusive. Early functional studies using CD30L+ cells or agonistic CD30-specific antibodies logically focused attention on cell types that had been shown to express CD30, namely certain lymphoid malignancies and subsets of activated T cells. However, it was not immediately clear how the reported activities from these in vitro studies relate to the biological activity of CD30L in the more complex whole animal setting. Recently, results from in vivo models involving CD30 or CD30L gene disruption, CD30L overexpression, or pharmacological blockade of CD30/CD30L interactions have begun to provide clues about the role played by CD30L in immunological processes. In this review we consider the reported biology of CD30L and focus on results from several recent studies that point to an important role for CD30/CD30L interactions in humoral immune responses. PMID:16771849

Fine mapping and positional candidate studies on chromosome 5p13 identify multiple asthma susceptibility loci.

PubMed

Kurz, Thorsten; Hoffjan, Sabine; Hayes, M Geoffrey; Schneider, Dan; Nicolae, Raluca; Heinzmann, Andrea; Jerkic, Sylvija P; Parry, Rod; Cox, Nancy J; Deichmann, Klaus A; Ober, Carole

2006-08-01

Genome-wide linkage scans to identify asthma susceptibility loci have revealed many linked regions, including a broad region on chromosome 5p. To identify a 5p-linked asthma or bronchial hyperresponsiveness (BHR) locus. We performed fine mapping and positional candidate studies of this region in the Hutterites and an outbred case-control sample from Germany by genotyping 89 single nucleotide polymorphisms (SNPs) in 22 genes. SNP and haplotype analyses were performed. Three genes in a distal region (zinc finger RNA binding protein [ZFR], natriuretic peptide receptor C, and a disintegrin and metalloproteinase domain with thrombospondin type 1 motif [ADAMTS12]) were associated with BHR, whereas 4 genes in a proximal region (prolactin receptor, IL-7 receptor [IL7R], leukemia inhibitory factor receptor [LIFR], and prostaglandin E4 receptor [PTGER4]) were associated with asthma symptoms in the Hutterites. Furthermore, nearly the entire original linkage signal in the Hutterites was generated by individuals who had the risk-associated alleles in ZFR3, natriuretic peptide receptor C, ADAMTS12, LIFR, and PTGER4. Variation in ADAMTS12, IL7R, and PTGER4 were also associated with asthma in the outbred Germans, and the frequencies of long-range haplotypes composed of SNPs at ZFR, ADAMTS12, IL7R, LIFR, and PTGER4 were significantly different between both the German and Hutterite cases and controls. There is little linkage disequilbrium between alleles in these 2 regions in either population. These results suggest that a broad region on 5p, separated by >9 Mb, harbors at least 2 and possibly 5 asthma or BHR susceptibility loci. These findings are consistent with the hypothesis that regions providing evidence for linkage in multiple populations may, in fact, house more than 1 susceptibility locus, as appears to be the case for the linked region on 5p. Identifying asthma or BHR genes could lead to novel therapeutic approaches.

Extensive cargo identification reveals distinct biological roles of the 12 importin pathways.

PubMed

Kimura, Makoto; Morinaka, Yuriko; Imai, Kenichiro; Kose, Shingo; Horton, Paul; Imamoto, Naoko

2017-01-24

Vast numbers of proteins are transported into and out of the nuclei by approximately 20 species of importin-β family nucleocytoplasmic transport receptors. However, the significance of the multiple parallel transport pathways that the receptors constitute is poorly understood because only limited numbers of cargo proteins have been reported. Here, we identified cargo proteins specific to the 12 species of human import receptors with a high-throughput method that employs stable isotope labeling with amino acids in cell culture, an in vitro reconstituted transport system, and quantitative mass spectrometry. The identified cargoes illuminated the manner of cargo allocation to the receptors. The redundancies of the receptors vary widely depending on the cargo protein. Cargoes of the same receptor are functionally related to one another, and the predominant protein groups in the cargo cohorts differ among the receptors. Thus, the receptors are linked to distinct biological processes by the nature of their cargoes.

Proteasome subunit Rpn13 is a novel ubiquitin receptor

PubMed Central

Husnjak, Koraljka; Elsasser, Suzanne; Zhang, Naixia; Chen, Xiang; Randles, Leah; Shi, Yuan; Hofmann, Kay; Walters, Kylie; Finley, Daniel; Dikic, Ivan

2010-01-01

Proteasomal receptors that recognize ubiquitin chains attached to substrates are key mediators of selective protein degradation in eukaryotes. Here we report the identification of a new ubiquitin receptor, Rpn13/ARM1, a known component of the proteasome. Rpn13 binds ubiquitin via a conserved N-terminal region termed the Pru domain (Pleckstrin-like receptor for ubiquitin), which binds K48-linked diubiquitin with an affinity of ∼90 nM. Like proteasomal ubiquitin receptor Rpn10/S5a, Rpn13 also binds ubiquitin-like domains of the UBL/UBA family of ubiquitin receptors. A synthetic phenotype results in yeast when specific mutations of the ubiquitin binding sites of Rpn10 and Rpn13 are combined, indicating functional linkage between these ubiquitin receptors. Since Rpn13 is also the proteasomal receptor for Uch37, a deubiquitinating enzyme, our findings suggest a coupling of chain recognition and disassembly at the proteasome. PMID:18497817

Rasgrf2 controls dopaminergic adaptations to alcohol in mice.

PubMed

Easton, Alanna C; Rotter, Andrea; Lourdusamy, Anbarasu; Desrivières, Sylvane; Fernández-Medarde, Alberto; Biermann, Teresa; Fernandes, Cathy; Santos, Eugenio; Kornhuber, Johannes; Schumann, Gunter; Müller, Christian P

2014-10-01

Alcohol abuse leads to serious health problems with no effective treatment available. Recent evidence suggests a role for ras-specific guanine-nucleotide releasing factor 2 (RASGRF2) in alcoholism. Rasgrf2 is a calcium sensor and MAPK/ERK activating protein, which has been linked to neurotransmitter release and monoaminergic receptor adaptations. Rasgrf2 knock out (KO) mice do not develop a dopamine response in the nucleus accumbens after an alcohol challenge and show a reduced consumption of alcohol. The present study aims to further characterise the role of Rasgrf2 in dopaminergic activation beyond the nucleus accumbens following alcohol treatment. Using in vivo microdialysis we found that alcohol induces alterations in dopamine levels in the dorsal striatum between wildtype (WT) and Rasgrf2 KO mice. There was no difference in the expression of dopamine transporter (DAT), dopamine receptor regulating factor (DRRF), or dopamine D2 receptor (DRD2) mRNA in the brain between Rasgrf2 KO and WT mice. After sub-chronic alcohol treatment, DAT and DRRF, but not DRD2 mRNA expression differed between WT and Rasgrf2 KO mice. Brain adaptations were positively correlated with splenic expression levels. These data suggest that Rasgrf2 controls dopaminergic signalling and adaptations to alcohol also in other brain regions, beyond the nucleus accumbens. Copyright © 2014 Elsevier Inc. All rights reserved.

Is desire for social relationships mediated by the serotonergic system in the prefrontal cortex? An [(18)F]setoperone PET study.

PubMed

Gerretsen, Philip; Graff-Guerrero, Ariel; Menon, Mahesh; Pollock, Bruce G; Kapur, Shitij; Vasdev, Neil; Houle, Sylvain; Mamo, David

2010-01-01

Social behavior and desire for social relationships have been independently linked to the serotonergic system, the prefrontal cortex, especially the orbitofrontal cortex (OFC), and the anterior cingulate cortex (ACC). The goal of this study was to explore the role of serotonin 5HT(2A) receptors in these brain regions in forming and maintaining close interpersonal relationships. Twenty-four healthy subjects completed the Temperament and Character Inventory (TCI) prior to undergoing [(18)F]setoperone brain positron emission tomography (PET) to measure serotonin 5HT(2A) receptor availability within the OFC (BA 11 and 47) and ACC (BA 32). We explored the relationship between desire for social relationships, as measured by the TCI reward dependence (RD) scale, and 5HT(2A) receptor non-displaceable binding potential (BP(nd)) in these regions. Scores of RD were negatively correlated with 5HT(2A) BP(nd) in the ACC (BA 32, r = -.528, p = .012) and OFC (BA 11, r = -.489, p = .021; BA 47, r = -.501, p = .017). These correlations were corroborated by a voxel-wise analysis. These results suggest that the serotonergic system may have a regulatory effect on the OFC and ACC for establishing and maintaining social relationships.

Research resource: Tissue-specific transcriptomics and cistromics of nuclear receptor signaling: a web research resource.

PubMed

Ochsner, Scott A; Watkins, Christopher M; LaGrone, Benjamin S; Steffen, David L; McKenna, Neil J

2010-10-01

Nuclear receptors (NRs) are ligand-regulated transcription factors that recruit coregulators and other transcription factors to gene promoters to effect regulation of tissue-specific transcriptomes. The prodigious rate at which the NR signaling field has generated high content gene expression and, more recently, genome-wide location analysis datasets has not been matched by a committed effort to archiving this information for routine access by bench and clinical scientists. As a first step towards this goal, we searched the MEDLINE database for studies, which referenced either expression microarray and/or genome-wide location analysis datasets in which a NR or NR ligand was an experimental variable. A total of 1122 studies encompassing 325 unique organs, tissues, primary cells, and cell lines, 35 NRs, and 91 NR ligands were retrieved and annotated. The data were incorporated into a new section of the Nuclear Receptor Signaling Atlas Molecule Pages, Transcriptomics and Cistromics, for which we designed an intuitive, freely accessible user interface to browse the studies. Each study links to an abstract, the MEDLINE record, and, where available, Gene Expression Omnibus and ArrayExpress records. The resource will be updated on a regular basis to provide a current and comprehensive entrez into the sum of transcriptomic and cistromic research in this field.

Comparing Plant and Animal Glutamate Receptors: Common Traits but Different Fates?

PubMed

Wudick, Michael M; Michard, Erwan; Oliveira Nunes, Custódio; Feijó, José A

2018-04-19

Animal ionotropic glutamate receptors (iGluRs) are ligand-gated channels whose evolution is intimately linked to the one of the nervous system, where the agonist glutamate and co-agonists glycine/D-serine act as neuro-transmitters or -modulators. While iGluRs are specialized in neuronal communication, plant glutamate receptor-like (GLR) homologues have evolved many plant-specific physiological functions, such as sperm signaling in moss, pollen tube growth, root meristem proliferation, innate immune and wound responses. GLRs have been associated with Ca2+ signaling by directly channeling its extracellular influx into the cytosol. Nevertheless, very limited information on functional properties of GLRs is available, and we mostly rely on structure/function data obtained for animal iGluRs to interpret experimental results obtained for plant GLRs. Yet, a deeper characterization and better understanding of plant GLRs is progressively unveiling original and different mode of functions when compared to their mammalian counterparts. Here, we review the function of plant GLRs comparing their predicted structure and physiological roles to the well-documented ones of iGluRs. We conclude that interpreting GLR function based on comparison to their animal counterparts calls for caution, especially when presuming physiological roles and mode of action for plant GLRs from comparison to iGluRs in peripheral, non-neuronal tissues.

Association between cerebral cannabinoid 1 receptor availability and body mass index in patients with food intake disorders and healthy subjects: a [(18)F]MK-9470 PET study.

PubMed

Ceccarini, J; Weltens, N; Ly, H G; Tack, J; Van Oudenhove, L; Van Laere, K

2016-07-12

Although of great public health relevance, the mechanisms underlying disordered eating behavior and body weight regulation remain insufficiently understood. Compelling preclinical evidence corroborates a critical role of the endocannabinoid system (ECS) in the central regulation of appetite and food intake. However, in vivo human evidence on ECS functioning in brain circuits involved in food intake regulation as well as its relationship with body weight is lacking, both in health and disease. Here, we measured cannabinoid 1 receptor (CB1R) availability using positron emission tomography (PET) with [(18)F]MK-9470 in 54 patients with food intake disorders (FID) covering a wide body mass index (BMI) range (anorexia nervosa, bulimia nervosa, functional dyspepsia with weight loss and obesity; BMI range=12.5-40.6 kg/m(2)) and 26 age-, gender- and average BMI-matched healthy subjects (BMI range=18.5-26.6 kg/m(2)). The association between regional CB1R availability and BMI was assessed within predefined homeostatic and reward-related regions of interest using voxel-based linear regression analyses. CB1R availability was inversely associated with BMI in homeostatic brain regions such as the hypothalamus and brainstem areas in both patients with FID and healthy subjects. However, in FID patients, CB1R availability was also negatively correlated with BMI throughout the mesolimbic reward system (midbrain, striatum, insula, amygdala and orbitofrontal cortex), which constitutes the key circuit implicated in processing appetitive motivation and hedonic value of perceived food rewards. Our results indicate that the cerebral homeostatic CB1R system is inextricably linked to BMI, with additional involvement of reward areas under conditions of disordered body weight.

Vasopressin-independent targeting of aquaporin-2 by selective E-prostanoid receptor agonists alleviates nephrogenic diabetes insipidus.

PubMed

Olesen, Emma T B; Rützler, Michael R; Moeller, Hanne B; Praetorius, Helle A; Fenton, Robert A

2011-08-02

In the kidney, the actions of vasopressin on its type-2 receptor (V2R) induce increased water reabsorption alongside polyphosphorylation and membrane targeting of the water channel aquaporin-2 (AQP2). Loss-of-function mutations in the V2R cause X-linked nephrogenic diabetes insipidus. Treatment of this condition would require bypassing the V2R to increase AQP2 membrane targeting, but currently no specific pharmacological therapy is available. The present study examined specific E-prostanoid receptors for this purpose. In vitro, prostaglandin E2 (PGE2) and selective agonists for the E-prostanoid receptors EP2 (butaprost) or EP4 (CAY10580) all increased trafficking and ser-264 phosphorylation of AQP2 in Madin-Darby canine kidney cells. Only PGE2 and butaprost increased cAMP and ser-269 phosphorylation of AQP2. Ex vivo, PGE2, butaprost, or CAY10580 increased AQP2 phosphorylation in isolated cortical tubules, whereas PGE2 and butaprost selectively increased AQP2 membrane accumulation in kidney slices. In vivo, a V2R antagonist caused a severe urinary concentrating defect in rats, which was greatly alleviated by treatment with butaprost. In conclusion, EP2 and EP4 agonists increase AQP2 phosphorylation and trafficking, likely through different signaling pathways. Furthermore, EP2 selective agonists can partially compensate for a nonfunctional V2R, providing a rationale for new treatment strategies for hereditary nephrogenic diabetes insipidus.

Vasopressin-independent targeting of aquaporin-2 by selective E-prostanoid receptor agonists alleviates nephrogenic diabetes insipidus

PubMed Central

Olesen, Emma T. B.; Rützler, Michael R.; Moeller, Hanne B.; Praetorius, Helle A.; Fenton, Robert A.

2011-01-01

In the kidney, the actions of vasopressin on its type-2 receptor (V2R) induce increased water reabsorption alongside polyphosphorylation and membrane targeting of the water channel aquaporin-2 (AQP2). Loss-of-function mutations in the V2R cause X-linked nephrogenic diabetes insipidus. Treatment of this condition would require bypassing the V2R to increase AQP2 membrane targeting, but currently no specific pharmacological therapy is available. The present study examined specific E-prostanoid receptors for this purpose. In vitro, prostaglandin E2 (PGE2) and selective agonists for the E-prostanoid receptors EP2 (butaprost) or EP4 (CAY10580) all increased trafficking and ser-264 phosphorylation of AQP2 in Madin-Darby canine kidney cells. Only PGE2 and butaprost increased cAMP and ser-269 phosphorylation of AQP2. Ex vivo, PGE2, butaprost, or CAY10580 increased AQP2 phosphorylation in isolated cortical tubules, whereas PGE2 and butaprost selectively increased AQP2 membrane accumulation in kidney slices. In vivo, a V2R antagonist caused a severe urinary concentrating defect in rats, which was greatly alleviated by treatment with butaprost. In conclusion, EP2 and EP4 agonists increase AQP2 phosphorylation and trafficking, likely through different signaling pathways. Furthermore, EP2 selective agonists can partially compensate for a nonfunctional V2R, providing a rationale for new treatment strategies for hereditary nephrogenic diabetes insipidus. PMID:21768374

Innate sensors of pathogen and stress: linking inflammation to obesity.

PubMed

Jin, Chengcheng; Flavell, Richard A

2013-08-01

Pathogen and nutrient response pathways are evolutionarily conserved and highly integrated to regulate metabolic and immune homeostasis. Excessive nutrients can be sensed by innate pattern recognition receptors as danger signals either directly or through production of endogenous ligands or modulation of intestinal microbiota. This triggers the activation of downstream inflammatory cascades involving nuclear factor κB and mitogen-activated protein kinase and ultimately induces the production of inflammatory cytokines and immune cell infiltration in various metabolic tissues. The chronic low-grade inflammation in the brain, islet, liver, muscle, and adipose tissue further promotes insulin resistance, energy imbalance, and impaired glucose/lipid metabolism, contributing to the metabolic complications of obesity, such as diabetes and atherosclerosis. In addition, innate pathogen receptors have now emerged as a critical link between the intestinal microbiota and host metabolism. In this review we summarize recent studies demonstrating the important roles of innate pathogen receptors, including Toll-like receptors, nucleotide oligomerization domain containing proteins, and inflammasomes in mediating the inflammatory response to metabolic stress in different tissues and highlight the interaction of innate pattern recognition receptors, gut microbiota, and nutrients during the development of obesity and related metabolic disorders. Copyright © 2013 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

α-Helical element at the hormone-binding surface of the insulin receptor functions as a signaling element to activate its tyrosine kinase

PubMed Central

Whittaker, Jonathan; Whittaker, Linda J.; Roberts, Charles T.; Phillips, Nelson B.; Ismail-Beigi, Faramarz; Lawrence, Michael C.; Weiss, Michael A.

2012-01-01

The primary hormone-binding surface of the insulin receptor spans one face of the N-terminal β-helix of the α-subunit (the L1 domain) and an α-helix in its C-terminal segment (αCT). Crystallographic analysis of the free ectodomain has defined a contiguous dimer-related motif in which the αCT α-helix packs against L1 β-strands 2 and 3. To relate structure to function, we exploited expanded genetic-code technology to insert photo-activatable probes at key sites in L1 and αCT. The pattern of αCT-mediated photo–cross-linking within the free and bound receptor is in accord with the crystal structure and prior mutagenesis. Surprisingly, L1 photo-probes in β-strands 2 and 3, predicted to be shielded by αCT, efficiently cross-link to insulin. Furthermore, anomalous mutations were identified on neighboring surfaces of αCT and insulin that impair hormone-dependent activation of the intracellular receptor tyrosine kinase (contained within the transmembrane β-subunit) disproportionately to their effects on insulin binding. Taken together, these results suggest that αCT, in addition to its hormone-recognition role, provides a signaling element in the mechanism of receptor activation. PMID:22736795

α-Helical element at the hormone-binding surface of the insulin receptor functions as a signaling element to activate its tyrosine kinase.

PubMed

Whittaker, Jonathan; Whittaker, Linda J; Roberts, Charles T; Phillips, Nelson B; Ismail-Beigi, Faramarz; Lawrence, Michael C; Weiss, Michael A

2012-07-10

The primary hormone-binding surface of the insulin receptor spans one face of the N-terminal β-helix of the α-subunit (the L1 domain) and an α-helix in its C-terminal segment (αCT). Crystallographic analysis of the free ectodomain has defined a contiguous dimer-related motif in which the αCT α-helix packs against L1 β-strands 2 and 3. To relate structure to function, we exploited expanded genetic-code technology to insert photo-activatable probes at key sites in L1 and αCT. The pattern of αCT-mediated photo-cross-linking within the free and bound receptor is in accord with the crystal structure and prior mutagenesis. Surprisingly, L1 photo-probes in β-strands 2 and 3, predicted to be shielded by αCT, efficiently cross-link to insulin. Furthermore, anomalous mutations were identified on neighboring surfaces of αCT and insulin that impair hormone-dependent activation of the intracellular receptor tyrosine kinase (contained within the transmembrane β-subunit) disproportionately to their effects on insulin binding. Taken together, these results suggest that αCT, in addition to its hormone-recognition role, provides a signaling element in the mechanism of receptor activation.

The Role of Estrogen Related Receptor in Modulating Estrogen Receptor Mediated Transcription in Breast Cancer Cells

DTIC Science & Technology

2005-04-01

tumors correlates with an unfavorable prognosis (Ariazi 2002; Lu 2001; Suzuki 2004; Vanacker 1999). The transcriptional activity of ERRa is not inhibited...SA. 101:6570-5. Needham, M ., S. Raines, J. McPheat, C. Stacey, J. Ellston, S. Hoare, and M . Parker. 2000. Differential interaction of steroid hormone...R. Graves, M . Wright, and B.M. Spiegelman. 1998. A cold- inducible coactivator of nuclear receptors linked to adaptive thermogenesis. Cell. 92:829- 39

Chemosensory receptors in tsetse flies provide link between chemical and behavioural ecology

PubMed Central

Masiga, Daniel; Obiero, George; Macharia, Rosaline; Mireji, Paul; Christoffels, Alan

2015-01-01

Tsetse flies survive in a variety of environments across tropical Africa, often rising to large numbers, despite their low birth rate of one offspring every seven to nine days. They use olfactory receptors to process chemical signals in their environments to find food, escape from predators, and locate suitable larviposition sites. We discuss the identification of odorant and gustatory receptors in Glossina morsitans morsitans and the role genomics could play in management of nuisance insects. PMID:25017128

Mechanistic Target of Rapamycin Is a Novel Molecular Mechanism Linking Folate Availability and Cell Function.

PubMed

Silva, Elena; Rosario, Fredrick J; Powell, Theresa L; Jansson, Thomas

2017-07-01

Folate deficiency has been linked to a wide range of disorders, including cancer, neural tube defects, and fetal growth restriction. Folate regulates cellular function mediated by its involvement in the synthesis of nucleotides, which are needed for DNA synthesis, and its function as a methyl donor, which is critical for DNA methylation. Here we review current data showing that folate sensing by mechanistic target of rapamycin (mTOR) constitutes a novel and distinct pathway by which folate modulates cell functions such as nutrient transport, protein synthesis, and mitochondrial respiration. The mTOR signaling pathway responds to growth factors and changes in nutrient availability to control cell growth, proliferation, and metabolism. mTOR exists in 2 complexes, mTOR complex (mTORC) 1 and mTORC2, which have distinct upstream regulators and downstream targets. Folate deficiency in pregnant mice caused a marked inhibition of mTORC1 and mTORC2 signaling in multiple maternal and fetal tissues, downregulation of placental amino acid transporters, and fetal growth restriction. In addition, folate deficiency in primary human trophoblast (PHT) cells resulted in inhibition of mTORC1 and mTORC2 signaling and decreased the activity of key amino acid transporters. Folate sensing by mTOR in PHT cells is independent of the accumulation of homocysteine and requires the proton-coupled folate transporter (PCFT; solute carrier 46A1). Furthermore, mTORC1 and mTORC2 regulate trophoblast folate uptake by modulating the cell surface expression of folate receptor α and the reduced folate carrier. These findings, which provide a novel link between folate availability and cell function, growth, and proliferation, may have broad biological significance given the critical role of folate in normal cell function and the multiple diseases that have been associated with decreased or excessive folate availability. Low maternal folate concentrations are linked to restricted fetal growth, and we propose that the underlying mechanisms involve trophoblast mTOR folate sensing resulting in inhibition of mTORC1 and mTORC2 and downregulation of placental amino acid transporters. © 2017 American Society for Nutrition.

Analysis of Nuclear Factor-κB (NF-κB) Essential Modulator (NEMO) Binding to Linear and Lysine-linked Ubiquitin Chains and Its Role in the Activation of NF-κB*

PubMed Central

Kensche, Tobias; Tokunaga, Fuminori; Ikeda, Fumiyo; Goto, Eiji; Iwai, Kazuhiro; Dikic, Ivan

2012-01-01

Nuclear factor-κB (NF-κB) essential modulator (NEMO), a component of the inhibitor of κB kinase (IKK) complex, controls NF-κB signaling by binding to ubiquitin chains. Structural studies of NEMO provided a rationale for the specific binding between the UBAN (ubiquitin binding in ABIN and NEMO) domain of NEMO and linear (Met-1-linked) di-ubiquitin chains. Full-length NEMO can also interact with Lys-11-, Lys-48-, and Lys-63-linked ubiquitin chains of varying length in cells. Here, we show that purified full-length NEMO binds preferentially to linear ubiquitin chains in competition with lysine-linked ubiquitin chains of defined length, including long Lys-63-linked deca-ubiquitins. Linear di-ubiquitins were sufficient to activate both the IKK complex in vitro and to trigger maximal NF-κB activation in cells. In TNFα-stimulated cells, NEMO chimeras engineered to bind exclusively to Lys-63-linked ubiquitin chains mediated partial NF-κB activation compared with cells expressing NEMO that binds to linear ubiquitin chains. We propose that NEMO functions as a high affinity receptor for linear ubiquitin chains and a low affinity receptor for long lysine-linked ubiquitin chains. This phenomenon could explain quantitatively distinct NF-κB activation patterns in response to numerous cell stimuli. PMID:22605335

Schizophrenia, dissociative anaesthesia and near-death experience; three events meeting at the NMDA receptor.

PubMed

Bonta, Iván L

2004-01-01

The three events, viz. schizophrenia, dissociative anaesthesia and Near-Death Experience, despite their seemingly unrelated manifestation to each other, have nevertheless similar functional basis. All three events are linked to the glutamate sensitive N-methyl-D-aspartate (NMDA) receptor complex, which serves as their common functional denominator. Arguments and speculations are presented in favor of the view that, the three events might be considered as functional models of each other. Antagonism to the recognition NMDA-site of the receptor induces dissociative anaesthesia and precipitates Near-Death Experience. Agonist reinforcement at the modulatory glycine-site of the receptor counteracts negative symptoms of schizophrenia. Both types of challenges towards the receptor are compatible with a glutamate deficiency concept which underlies the meeting of the three events at the NMDA receptor.

SLP-76 is required for high-affinity IgE receptor- and IL-3 receptor-mediated activation of basophils.

PubMed

Hidano, Shinya; Kitamura, Daisuke; Kumar, Lalit; Geha, Raif S; Goitsuka, Ryo

2012-11-01

Basophils have been reported to play a critical role in allergic inflammation by secreting IL-4 in response to IL-3 or high-affinity IgE receptor (FcεRI)-cross-linking. However, the signaling pathways downstream of FcεRI and the IL-3 receptor in basophils have yet to be determined. In the present study, we used mice deficient in SLP-76 (Src homology 2 domain-containing leukocyte phosphoprotein of 76kDa) to demonstrate critical functions of this adaptor molecule in transducing FcεRI- and IL-3 receptor-mediated signals that induce basophil activation. Although SLP-76 was dispensable for in vivo differentiation, as well as IL-3-induced in vitro proliferation of basophils, IL-4 production induced by both stimuli was completely ablated by SLP-76 deficiency. Biochemical analyses revealed that IL-3-induced phosphorylation of phospholipase C (PLC) γ2 and Akt, but not STAT5, was severely reduced in SLP-76-deficient basophils, whereas FcεRI cross-linking phosphorylation of PLCγ2, but not Akt, was abrogated by SLP-76 deficiency, suggesting important differences in the requirement of SLP-76 for Akt activation between FcεRI- and IL-3 receptor-mediated signaling pathways in basophils. Because IL-3-induced IL-4 production was sensitive to calcineurin inhibitors and an intracellular calcium chelator, in addition to PI3K inhibitors, SLP-76 appears to regulate FcεRI- and IL-3 receptor-induced IL-4 production via mediating PLCγ2 activation in basophils. Taken together, these findings indicate that SLP-76 is an essential signaling component for basophil activation downstream of both FcεRI and the IL-3 receptor.

Group 1 Metabotropic Glutamate Receptor Function and Its Regulation of Learning and Memory in the Aging Brain

PubMed Central

Ménard, Caroline; Quirion, Rémi

2012-01-01

Normal aging is generally characterized by a slow decline of cognitive abilities albeit with marked individual differences. Several animal models have been studied to explore the molecular and cellular mechanisms underlying this phenomenon. The excitatory neurotransmitter glutamate and its receptors have been closely linked to spatial learning and hippocampus-dependent memory processes. For decades, ionotropic glutamate receptors have been known to play a critical role in synaptic plasticity, a form of adaptation regulating memory formation. Over the past 10 years, several groups have shown the importance of group 1 metabotropic glutamate receptor (mGluR) in successful cognitive aging. These G-protein-coupled receptors are enriched in the hippocampal formation and interact physically with other proteins in the membrane including glutamate ionotropic receptors. Synaptic plasticity is crucial to maintain cognitive abilities and long-term depression (LTD) induced by group 1 mGluR activation, which has been linked to memory in the aging brain. The translation and synthesis of proteins by mGluR-LTD modulate ionotropic receptor trafficking and expression of immediate early genes related to cognition. Fragile X syndrome, a genetic form of autism characterized by memory deficits, has been associated to mGluR receptor malfunction and aberrant activation of its downstream signaling pathways. Dysfunction of mGluR could also be involved in neurodegenerative disorders like Alzheimer’s disease (AD). Indeed, beta-amyloid, the main component of insoluble senile plaques and one of the hallmarks of AD, occludes mGluR-dependent LTD leading to diminished functional synapses. This review highlights recent findings regarding mGluR signaling, related synaptic plasticity, and their potential involvement in normal aging and neurological disorders. PMID:23091460

Group 1 metabotropic glutamate receptor function and its regulation of learning and memory in the aging brain.

PubMed

Ménard, Caroline; Quirion, Rémi

2012-01-01

Normal aging is generally characterized by a slow decline of cognitive abilities albeit with marked individual differences. Several animal models have been studied to explore the molecular and cellular mechanisms underlying this phenomenon. The excitatory neurotransmitter glutamate and its receptors have been closely linked to spatial learning and hippocampus-dependent memory processes. For decades, ionotropic glutamate receptors have been known to play a critical role in synaptic plasticity, a form of adaptation regulating memory formation. Over the past 10 years, several groups have shown the importance of group 1 metabotropic glutamate receptor (mGluR) in successful cognitive aging. These G-protein-coupled receptors are enriched in the hippocampal formation and interact physically with other proteins in the membrane including glutamate ionotropic receptors. Synaptic plasticity is crucial to maintain cognitive abilities and long-term depression (LTD) induced by group 1 mGluR activation, which has been linked to memory in the aging brain. The translation and synthesis of proteins by mGluR-LTD modulate ionotropic receptor trafficking and expression of immediate early genes related to cognition. Fragile X syndrome, a genetic form of autism characterized by memory deficits, has been associated to mGluR receptor malfunction and aberrant activation of its downstream signaling pathways. Dysfunction of mGluR could also be involved in neurodegenerative disorders like Alzheimer's disease (AD). Indeed, beta-amyloid, the main component of insoluble senile plaques and one of the hallmarks of AD, occludes mGluR-dependent LTD leading to diminished functional synapses. This review highlights recent findings regarding mGluR signaling, related synaptic plasticity, and their potential involvement in normal aging and neurological disorders.

Interleukin-1 and cutaneous inflammation: a crucial link between innate and acquired immunity.

PubMed

Murphy, J E; Robert, C; Kupper, T S

2000-03-01

As our primary interface with the environment, the skin is constantly subjected to injury and invasion by pathogens. The fundamental force driving the evolution of the immune system has been the need to protect the host against overwhelming infection. The ability of T and B cells to recombine antigen receptor genes during development provides an efficient, flexible, and powerful immune system with nearly unlimited specificity for antigen. The capacity to expand subsets of antigen-specific lymphocytes that become activated by environmental antigens (memory response) is termed "acquired" immunity. Immunologic memory, although a fundamental aspect of mammalian biology, is a relatively recent evolutionary event that permits organisms to live for years to decades. "Innate" immunity, mediated by genes that remain in germ line conformation and encode for proteins that recognize conserved structural patterns on microorganisms, is a much more ancient system of host defense. Defensins and other antimicrobial peptides, complement and opsonins, and endocytic receptors are all considered components of the innate immune system. None of these, however, are signal-transducing receptors. Most recently, a large family of cell surface receptors that mediate signaling through the NF-kappaB transcription factor has been identified. This family of proteins shares striking homology with plant and Drosophila genes that mediate innate immunity. In mammals, this family includes the type I interleukin-1 receptor, the interleukin-18 receptor, and a growing family of Toll-like receptors, two of which were recently identified as signal-transducing receptors for bacterial endotoxin. In this review, we discuss how interleukin-1 links the innate and acquired immune systems to provide synergistic host defense activities in skin.

Olfactomedin-1 Has a V-shaped Disulfide-linked Tetrameric Structure*

PubMed Central

Pronker, Matti F.; Bos, Trusanne G. A. A.; Sharp, Thomas H.; Thies-Weesie, Dominique M. E.; Janssen, Bert J. C.

2015-01-01

Olfactomedin-1 (Olfm1; also known as noelin and pancortin) is a member of the olfactomedin domain-containing superfamily and a highly expressed neuronal glycoprotein important for nervous system development. It binds a number of secreted proteins and cell surface-bound receptors to induce cell signaling processes. Using a combined approach of x-ray crystallography, solution scattering, analytical ultracentrifugation, and electron microscopy we determined that full-length Olfm1 forms disulfide-linked tetramers with a distinctive V-shaped architecture. The base of the “V” is formed by two disulfide-linked dimeric N-terminal domains. Each of the two V legs consists of a parallel dimeric disulfide-linked coiled coil with a C-terminal β-propeller dimer at the tips. This agrees with our crystal structure of a C-terminal coiled-coil segment and β-propeller combination (Olfm1coil-Olf) that reveals a disulfide-linked dimeric arrangement with the β-propeller top faces in an outward exposed orientation. Similar to its family member myocilin, Olfm1 is stabilized by calcium. The dimer-of-dimers architecture suggests a role for Olfm1 in clustering receptors to regulate signaling and sheds light on the conformation of several other olfactomedin domain family members. PMID:25903135

Androgen Receptor Gene Polymorphism, Aggression, and Reproduction in Tanzanian Foragers and Pastoralists

PubMed Central

Butovskaya, Marina L.; Lazebny, Oleg E.; Vasilyev, Vasiliy A.; Dronova, Daria A.; Karelin, Dmitri V.; Mabulla, Audax Z. P.; Shibalev, Dmitri V.; Shackelford, Todd K.; Fink, Bernhard; Ryskov, Alexey P.

2015-01-01

The androgen receptor (AR) gene polymorphism in humans is linked to aggression and may also be linked to reproduction. Here we report associations between AR gene polymorphism and aggression and reproduction in two small-scale societies in northern Tanzania (Africa)—the Hadza (monogamous foragers) and the Datoga (polygynous pastoralists). We secured self-reports of aggression and assessed genetic polymorphism of the number of CAG repeats for the AR gene for 210 Hadza men and 229 Datoga men (aged 17–70 years). We conducted structural equation modeling to identify links between AR gene polymorphism, aggression, and number of children born, and included age and ethnicity as covariates. Fewer AR CAG repeats predicted greater aggression, and Datoga men reported more aggression than did Hadza men. In addition, aggression mediated the identified negative relationship between CAG repeats and number of children born. PMID:26291982

Human thyrotropin receptor subunits characterized by thyrotropin affinity purification and western blotting.

PubMed

Leedman, P J; Newman, J D; Harrison, L C

1989-07-01

We studied the subunit structure of the human TSH receptor in thyroid tissue from patients with Graves' disease and multinodular goiter by TSH affinity chromatography, immunoprecipitation with Graves' immunoglobulins (Igs), and a modified technique of Western blotting. Human TSH receptor-binding activity was purified about 1,270-fold by sequential affinity chromatography on wheat germ lectin-agarose and TSH-agarose. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of nonreduced affinity-purified receptors eluted in sodium dodecyl sulfate sample buffer revealed three noncovalently linked subunits of 70,000, 50,000, and 35,000 mol wt. When reduced, a major subunit of 25,000 mol wt was identified. When 3 mol/L NaCl was used to elute affinity-purified receptors only the 50,000 mol wt nonreduced subunit was detected. This subunit bound [125I]bovine TSH and was precipitated by Graves' Igs. Modifications to the conventional Western blotting technique enabled thyroglobulin components (approximately 220,000 mol wt), thyroid microsomal antigen (a doublet of approximately 110,000 mol wt), and putative TSH receptor subunits of 70,000 and 50,000 mol wt to be identified in thyroid particulate membranes by Graves' Igs. Blotting of affinity-purified receptors eluted in sodium dodecyl sulfate sample buffer revealed subunits of either 70,000 or 50,000 mol wt, with a minority of Graves' serum samples. We conclude that the nonreduced human TSH receptor is an oligomeric complex comprising three different subunits of 70,000, 50,000, and 35,000 mol wt. The reduced receptor exists as a single subunit of 25,000 mol wt, which may be disulfide linked to form the higher mol wt forms. The 70,000 and 50,000 mol wt subunits contain epitopes that bind Graves' Igs in modified Western blots, thus directly confirming that the human TSH receptor is a target for Graves' Igs.

Striatal dopamine D2 receptor availability predicts the thalamic and medial prefrontal responses to reward in cocaine abusers three years later

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

Asensio, S.; Goldstein, R.; Asensio, S.

Low levels of dopamine (DA) D2 receptor availability at a resting baseline have been previously reported in drug addicted individuals and have been associated with reduced ventral and dorsal prefrontal metabolism. The reduction in DA D2 receptor availability along with the reduced ventral frontal metabolism is thought to underlie compromised sensitivity to nondrug reward, a core characteristic of drug addiction. We therefore hypothesized that variability in DA D2 receptor availability at baseline will covary with dynamic responses to monetary reward in addicted individuals. Striatal DA D2 receptor availability was measured with [{sup 11}C]raclopride and positron emission tomography and response tomore » monetary reward was measured (an average of three years later) with functional magnetic resonance imaging in seven cocaine-addicted individuals. Results show that low DA D2 receptor availability in the dorsal striatum was associated with decreased thalamic response to monetary reward; while low availability in ventral striatum was associated with increased medial prefrontal (Brodmann Area 6/8/32) response to monetary reward. These preliminary results, that need to be replicated in larger sample sizes and validated with healthy controls, suggest that resting striatal DA D2 receptor availability predicts variability in functional responses to a nondrug reinforcer (money) in prefrontal cortex, implicated in behavioral monitoring, and in thalamus, implicated in conditioned responses and expectation, in cocaine-addicted individuals.« less

Striatal dopamine D2 receptor availability predicts the thalamic and medial prefrontal responses to reward in cocaine abusers three years later

PubMed Central

Asensio, Samuel; Romero, Maria J.; Romero, Francisco J.; Wong, Christopher; Alia-Klein, Nelly; Tomasi, Dardo; Wang, Gene-Jack; Telang, Frank; Volkow, Nora D.; Goldstein, Rita Z.

2009-01-01

Low levels of dopamine (DA) D2 receptor availability at a resting baseline have been previously reported in drug addicted individuals and have been associated with reduced ventral and dorsal prefrontal metabolism. The reduction in DA D2 receptor availability along with the reduced ventral frontal metabolism is thought to underlie compromised sensitivity to non-drug reward, a core characteristic of drug addiction. We therefore hypothesized that variability in DA D2 receptor availability at baseline will covary with dynamic responses to monetary reward in addicted individuals. Striatal DA D2 receptor availability was measured with [11C]raclopride and positron emission tomography and response to monetary reward was measured (an average of 3 years later) with functional magnetic resonance imaging in seven cocaine addicted individuals. Results show that low DA D2 receptor availability in the dorsal striatum was associated with decreased thalamic response to monetary reward; while low availability in ventral striatum was associated with increased medial prefrontal (Brodmann Area 6/8/32) response to monetary reward. These preliminary results, that need to be replicated in larger sample sizes and validated with healthy controls, suggest that resting striatal DA D2 receptor availability predicts variability in functional responses to a non-drug reinforcer (money) in prefrontal cortex, implicated in behavioral monitoring, and in thalamus, implicated in conditioned responses and expectation, in cocaine addicted individuals. PMID:20034014

The source of high signal cooperativity in bacterial chemosensory arrays

PubMed Central

Piñas, Germán E.; Frank, Vered; Vaknin, Ady; Parkinson, John S.

2016-01-01

The Escherichia coli chemosensory system consists of large arrays of transmembrane chemoreceptors associated with a dedicated histidine kinase, CheA, and a linker protein, CheW, that couples CheA activity to receptor control. The kinase activity responses to receptor ligand occupancy changes can be highly cooperative, reflecting allosteric coupling of multiple CheA and receptor molecules. Recent structural and functional studies have led to a working model in which receptor core complexes, the minimal units of signaling, are linked into hexagonal arrays through a unique interface 2 interaction between CheW and the P5 domain of CheA. To test this array model, we constructed and characterized CheA and CheW mutants with amino acid replacements at key interface 2 residues. The mutant proteins proved defective in interface 2-specific in vivo cross-linking assays, and formed signaling complexes that were dispersed around the cell membrane rather than clustered at the cell poles as in wild type chemosensory arrays. Interface 2 mutants down-regulated CheA activity in response to attractant stimuli in vivo, but with much less cooperativity than the wild type. Moreover, mutant cells containing fluorophore-tagged receptors exhibited greater basal anisotropy that changed rapidly in response to attractant stimuli, consistent with facile changes in loosely packed receptors. We conclude that interface 2 lesions disrupt important network connections between core complexes, preventing receptors from operating in large, allosteric teams. This work confirms the critical role of interface 2 in organizing the chemosensory array, in directing the clustered array to the cell poles, and in producing its highly cooperative signaling properties. PMID:26951681

Effect of Exercise Training on Striatal Dopamine D2/D3 Receptors in Methamphetamine Users during Behavioral Treatment.

PubMed

Robertson, Chelsea L; Ishibashi, Kenji; Chudzynski, Joy; Mooney, Larissa J; Rawson, Richard A; Dolezal, Brett A; Cooper, Christopher B; Brown, Amira K; Mandelkern, Mark A; London, Edythe D

2016-05-01

Methamphetamine use disorder is associated with striatal dopaminergic deficits that have been linked to poor treatment outcomes, identifying these deficits as an important therapeutic target. Exercise attenuates methamphetamine-induced neurochemical damage in the rat brain, and a preliminary observation suggests that exercise increases striatal D2/D3 receptor availability (measured as nondisplaceable binding potential (BPND)) in patients with Parkinson's disease. The goal of this study was to evaluate whether adding an exercise training program to an inpatient behavioral intervention for methamphetamine use disorder reverses deficits in striatal D2/D3 receptors. Participants were adult men and women who met DSM-IV criteria for methamphetamine dependence and were enrolled in a residential facility, where they maintained abstinence from illicit drugs of abuse and received behavioral therapy for their addiction. They were randomized to a group that received 1 h supervised exercise training (n=10) or one that received equal-time health education training (n=9), 3 days/week for 8 weeks. They came to an academic research center for positron emission tomography (PET) using [(18)F]fallypride to determine the effects of the 8-week interventions on striatal D2/D3 receptor BPND. At baseline, striatal D2/D3 BPND did not differ between groups. However, after 8 weeks, participants in the exercise group displayed a significant increase in striatal D2/D3 BPND, whereas those in the education group did not. There were no changes in D2/D3 BPND in extrastriatal regions in either group. These findings suggest that structured exercise training can ameliorate striatal D2/D3 receptor deficits in methamphetamine users, and warrants further evaluation as an adjunctive treatment for stimulant dependence.

Effect of Exercise Training on Striatal Dopamine D2/D3 Receptors in Methamphetamine Users during Behavioral Treatment

PubMed Central

Robertson, Chelsea L; Ishibashi, Kenji; Chudzynski, Joy; Mooney, Larissa J; Rawson, Richard A; Dolezal, Brett A; Cooper, Christopher B; Brown, Amira K; Mandelkern, Mark A; London, Edythe D

2016-01-01

Methamphetamine use disorder is associated with striatal dopaminergic deficits that have been linked to poor treatment outcomes, identifying these deficits as an important therapeutic target. Exercise attenuates methamphetamine-induced neurochemical damage in the rat brain, and a preliminary observation suggests that exercise increases striatal D2/D3 receptor availability (measured as nondisplaceable binding potential (BPND)) in patients with Parkinson's disease. The goal of this study was to evaluate whether adding an exercise training program to an inpatient behavioral intervention for methamphetamine use disorder reverses deficits in striatal D2/D3 receptors. Participants were adult men and women who met DSM-IV criteria for methamphetamine dependence and were enrolled in a residential facility, where they maintained abstinence from illicit drugs of abuse and received behavioral therapy for their addiction. They were randomized to a group that received 1 h supervised exercise training (n=10) or one that received equal-time health education training (n=9), 3 days/week for 8 weeks. They came to an academic research center for positron emission tomography (PET) using [18F]fallypride to determine the effects of the 8-week interventions on striatal D2/D3 receptor BPND. At baseline, striatal D2/D3 BPND did not differ between groups. However, after 8 weeks, participants in the exercise group displayed a significant increase in striatal D2/D3 BPND, whereas those in the education group did not. There were no changes in D2/D3 BPND in extrastriatal regions in either group. These findings suggest that structured exercise training can ameliorate striatal D2/D3 receptor deficits in methamphetamine users, and warrants further evaluation as an adjunctive treatment for stimulant dependence. PMID:26503310

Sweet proteins – Potential replacement for artificial low calorie sweeteners

PubMed Central

Kant, Ravi

2005-01-01

Exponential growth in the number of patients suffering from diseases caused by the consumption of sugar has become a threat to mankind's health. Artificial low calorie sweeteners available in the market may have severe side effects. It takes time to figure out the long term side effects and by the time these are established, they are replaced by a new low calorie sweetener. Saccharine has been used for centuries to sweeten foods and beverages without calories or carbohydrate. It was also used on a large scale during the sugar shortage of the two world wars but was abandoned as soon as it was linked with development of bladder cancer. Naturally occurring sweet and taste modifying proteins are being seen as potential replacements for the currently available artificial low calorie sweeteners. Interaction aspects of sweet proteins and the human sweet taste receptor are being investigated. PMID:15703077

The very large G-protein-coupled receptor VLGR1: a component of the ankle link complex required for the normal development of auditory hair bundles.

PubMed

McGee, Joann; Goodyear, Richard J; McMillan, D Randy; Stauffer, Eric A; Holt, Jeffrey R; Locke, Kirsten G; Birch, David G; Legan, P Kevin; White, Perrin C; Walsh, Edward J; Richardson, Guy P

2006-06-14

Sensory hair bundles in the inner ear are composed of stereocilia that can be interconnected by a variety of different link types, including tip links, horizontal top connectors, shaft connectors, and ankle links. The ankle link antigen is an epitope specifically associated with ankle links and the calycal processes of photoreceptors in chicks. Mass spectrometry and immunoblotting were used to identify this antigen as the avian ortholog of the very large G-protein-coupled receptor VLGR1, the product of the Usher syndrome USH2C (Mass1) locus. Like ankle links, Vlgr1 is expressed transiently around the base of developing hair bundles in mice. Ankle links fail to form in the cochleae of mice carrying a targeted mutation in Vlgr1 (Vlgr1/del7TM), and the bundles become disorganized just after birth. FM1-43 [N-(3-triethylammonium)propyl)-4-(4-(dibutylamino)styryl) pyridinium dibromide] dye loading and whole-cell recordings indicate mechanotransduction is impaired in cochlear, but not vestibular, hair cells of early postnatal Vlgr1/del7TM mutant mice. Auditory brainstem recordings and distortion product measurements indicate that these mice are severely deaf by the third week of life. Hair cells from the basal half of the cochlea are lost in 2-month-old Vlgr1/del7TM mice, and retinal function is mildly abnormal in aged mutants. Our results indicate that Vlgr1 is required for formation of the ankle link complex and the normal development of cochlear hair bundles.

σ Receptor antagonist attenuation of methamphetamine-induced neurotoxicity is correlated to body temperature modulation.

PubMed

Robson, Matthew J; Seminerio, Michael J; McCurdy, Christopher R; Coop, Andrew; Matsumoto, Rae R

2013-01-01

Methamphetamine (METH) causes hyperthermia and dopaminergic neurotoxicity in the rodent striatum. METH interacts with σ receptors and σ receptor antagonists normally mitigate METH-induced hyperthermia and dopaminergic neurotoxicity. The present study was undertaken because in two experiments, pretreatment with σ receptor antagonists failed to attenuate METH-induced hyperthermia in mice. This allowed us to determine whether the ability of σ receptor antagonists (AZ66 and AC927) to mitigate METH-induced neurotoxicity depends upon their ability to modulate METH-induced hyperthermia. Mice were treated using a repeated dosing paradigm and body temperatures recorded. Striatal dopamine was measured one week post-treatment. The data indicate that the ability of σ receptor antagonists to attenuate METH-induced dopaminergic neurotoxicity is linked to their ability to block METH-induced hyperthermia. The ability of σ receptor antagonists to mitigate METH-induced hyperthermia may contribute to its neuroprotective actions.

A new meaning for “Gin & Tonic”

PubMed Central

Mody, Istvan; Glykys, Joseph; Wei, Weizheng

2007-01-01

Gamma-aminobutyric acid (GABA) is the main chemical inhibitory neurotransmitter in the brain. In the central nervous system (CNS) it acts on two distinct types of receptor: an ion channel, i.e., an “ionotropic” receptor permeable to Cl- and HCO3- (GABAA receptors) and a G-protein coupled “metabotropic” receptor that is linked to various effector mechanisms (GABAB receptors). This review will summarize novel developments in the physiology and pharmacology of GABAA receptors (GABAARs), specifically those found outside synapses. The focus will be on a particular combination of GABAAR subunits responsible for mediating tonic inhibition and sensitive to concentrations of ethanol legally considered to be sobriety impairing. Since the same receptors are also a preferred target for the metabolites of steroid hormones synthesized in the brain (neurosteroids), the ethanol-sensitive tonic inhibition may be a common pathway for interactions between the effects of alcohol and those of ovarian and stress-related neurosteroids. PMID:17521846

TARPs differentially decorate AMPA receptors to specify neuropharmacology.

PubMed

Kato, Akihiko S; Gill, Martin B; Yu, Hong; Nisenbaum, Eric S; Bredt, David S

2010-05-01

Transmembrane AMPA receptor regulatory proteins (TARPs) are the first identified auxiliary subunits for a neurotransmitter-gated ion channel. Although initial studies found that stargazin, the prototypical TARP, principally chaperones AMPA receptors, subsequent research demonstrated that it also regulates AMPA receptor kinetics and synaptic waveforms. Recent studies have identified a diverse collection of TARP isoforms--types Ia, Ib II--that distinctly regulate AMPA receptor trafficking, gating and neuropharmacology. These TARP isoforms are heterogeneously expressed in specific neuronal populations and can differentially sculpt synaptic transmission and plasticity. Whole-genome analyses also link multiple TARP loci to childhood epilepsy, schizophrenia and bipolar disorder. TARPs emerge as vital components of excitatory synapses that participate both in signal transduction and in neuropsychiatric disorders. Copyright 2010 Elsevier Ltd. All rights reserved.

Recruitment of the cross-linked opsonic receptor CD32A (FcγRIIA) to high-density detergent-resistant membrane domains in human neutrophils

PubMed Central

2004-01-01

We have previously shown that CD32A (or FcγRIIA), one of the main opsonin receptors, was rapidly insolubilized and degraded in intact neutrophils after its cross-linking. In view of these experimental difficulties, the early signalling steps in response to CD32A activation were studied in purified plasma membranes of neutrophils. After CD32A cross-linking in these fractions, the tyrosine phosphorylation of two major substrates, the receptor itself and the tyrosine kinase Syk, was observed. Phosphorylation of these two proteins was observed only in the presence of orthovanadate, indicating the presence, in the membranes, of one or more tyrosine phosphatases that maintain CD32A dephosphorylation. The tyrosine phosphorylation of these two proteins was inhibited by the Src kinase inhibitor, 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2). The ligation of CD32A led to its recruitment to a previously uncharacterized subset of high-density flotillin-1-positive DRMs (detergent-resistant membranes). The changes in the solubility properties of CD32A were observed in the absence of added ATP; therefore, they were probably not secondary to the tyrosine phosphorylation of the receptor, rather they preceded it. Src kinases as well as Syk were constitutively present in DRMs of high and low density and no evident changes in their distribution were detected after cross-linking of CD32A. Pretreatment of plasma membranes with methyl-β-cyclodextrin did not inhibit the recruitment of CD32A to DRMs, although it led to the loss of the Src kinase Lyn from these fractions. In addition, methyl-β-cyclodextrin inhibited the tyrosine phosphorylation of CD32A and Syk induced by cross-linking of CD32A. This membrane model allowed us to observe a movement of CD32A from detergent-soluble regions of the membranes to DRMs, where it joined Src kinases and Syk and became tyrosine-phosphorylated. PMID:15130090

Principles of antibody-mediated TNF receptor activation

PubMed Central

Wajant, H

2015-01-01

From the beginning of research on receptors of the tumor necrosis factor (TNF) receptor superfamily (TNFRSF), agonistic antibodies have been used to stimulate TNFRSF receptors in vitro and in vivo. Indeed, CD95, one of the first cloned TNFRSF receptors, was solely identified as the target of cell death-inducing antibodies. Early on, it became evident from in vitro studies that valency and Fcγ receptor (FcγR) binding of antibodies targeting TNFRSF receptors can be of crucial relevance for agonistic activity. TNFRSF receptor-specific antibodies of the IgM subclass and secondary cross-linked or aggregation prone dimeric antibodies typically display superior agonistic activity compared with dimeric antibodies. Likewise, anchoring of antibodies to cell surface-expressed FcγRs potentiate their ability to trigger TNFRSF receptor signaling. However, only recently has the relevance of oligomerization and FcγR binding for the in vivo activity of antibody-induced TNFRSF receptor activation been straightforwardly demonstrated in vivo. This review discusses the crucial role of oligomerization and/or FcγR binding for antibody-mediated TNFRSF receptor stimulation in light of current models of TNFRSF receptor activation and especially the overwhelming relevance of these issues for the rational development of therapeutic TNFRSF receptor-targeting antibodies. PMID:26292758

Emerging roles for β-arrestin-1 in the control of the pancreatic β-cell function and mass: new therapeutic strategies and consequences for drug screening.

PubMed

Dalle, Stéphane; Ravier, Magalie A; Bertrand, Gyslaine

2011-03-01

Defective insulin secretion is a feature of type 2 diabetes that results from inadequate compensatory increase in β-cell mass, decreased β-cell survival and impaired glucose-dependent insulin release. Pancreatic β-cell proliferation, survival and secretion are thought to be regulated by signalling pathways linked to G-protein coupled receptors (GPCRs), such as the glucagon-like peptide-1 (GLP-1) and the pituitary adenylate cyclase-activating polypeptide (PACAP) receptors. β-arrestin-1 serves as a multifunctional adaptor protein that mediates receptor desensitization, receptor internalization, and links GPCRs to downstream pathways such as tyrosine kinase Src, ERK1/2 or Akt/PKB. Importantly, recent studies found that β-arrestin-1 mediates GLP-1 signalling to insulin secretion, GLP-1 antiapoptotic effect by phosphorylating the proapoptotic protein Bad through ERK1/2 activation, and PACAP potentiation of glucose-induced long-lasting ERK1/2 activation controlling IRS-2 expression. Together, these novel findings reveal an important functional role for β-arrestin-1 in the regulation of insulin secretion and β-cell survival by GPCRs. Copyright © 2010 Elsevier Inc. All rights reserved.

Multiple receptors mobilize calcium through a pertussis toxin (PT) sensitive GTP-binding protein in human neutrophils (PMN's)

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

Lad, P.M.; Olson, C.V.; Grewal, I.S.

1986-03-05

Treatment of PMN's with PT causes an abolition of chemotaxis, enzyme release, superoxide generation and aggregation caused by f-met-leu-phe (FMLP),C5a and platelet activating factor (PAF). Lectin (Con-A) induced capping and receptor induced shape change are abolished, but phagocytosis is unaltered. In whole cells, calcium mobilization induced by FMLP, PAF and Con-A inhibited by PT although the FMLP-mediated effect is more susceptible to PT's effects. Treatment of PMN's with phorbol 12-myristate 13 acetate (PMA) causes an abolition of calcium mobilization by all agents in a range which also inhibits cap formation. Investigation of calcium uptake reveals PT sensitive and insensitive components.more » Reciprocal interactions between Ns and Ni proteins are also observed since pretreatment with FMLP and PAF causes a stimulation of Ns-mediated cyclic AMP enhancement while pretreatment with Ns linked receptors (PGE/sub 1/ and beta receptor agonists) inhibits calcium mobilization. Comparative peptide mapping studies indicate substantial similarity between Ni proteins in PMN's, platelets and human erythrocytes. The authors results suggest that the Ni linked calcium mobilization sensitive to PMA is important to the regulation of the human neutrophil.« less

Lysosomal trafficking regulator Lyst links membrane trafficking to toll-like receptor–mediated inflammatory responses

PubMed Central

Krautkrämer, Martina

2017-01-01

Subcellular compartmentalization of receptor signaling is an emerging principle in innate immunity. However, the functional integration of receptor signaling pathways into membrane trafficking routes and its physiological relevance for immune responses is still largely unclear. In this study, using Lyst-mutant beige mice, we show that lysosomal trafficking regulator Lyst links endolysosomal organization to the selective control of toll-like receptor 3 (TLR3)– and TLR4-mediated proinflammatory responses. Consequently, Lyst-mutant mice showed increased susceptibility to bacterial infection and were largely resistant to endotoxin-induced septic shock. Mechanistic analysis revealed that Lyst specifically controls TLR3- and TLR4-induced endosomal TRIF (TIR domain–containing adapter-inducing interferon β) signaling pathways. Loss of functional Lyst leads to dysregulated phagosomal maturation, resulting in a failure to form an activation-induced Rab7+ endosomal/phagosomal compartment. This specific Rab7+ compartment was further demonstrated to serve as a major site for active TRIF signaling events, thus linking phagosomal maturation to specific TLR signaling pathways. The immunoregulatory role of Lyst on TLR signaling pathways was confirmed in human cells by CRISPR/Cas9-mediated gene inactivation. As mutations in LYST cause human Chédiak-Higashi syndrome, a severe immunodeficiency, our findings also contribute to a better understanding of human disease mechanisms. PMID:27881733

Effects of egg-adaptation on receptor-binding and antigenic properties of recent influenza A (H3N2) vaccine viruses.

PubMed

Parker, Lauren; Wharton, Stephen A; Martin, Stephen R; Cross, Karen; Lin, Yipu; Liu, Yan; Feizi, Ten; Daniels, Rodney S; McCauley, John W

2016-06-01

Influenza A virus (subtype H3N2) causes seasonal human influenza and is included as a component of influenza vaccines. The majority of vaccine viruses are isolated and propagated in eggs, which commonly results in amino acid substitutions in the haemagglutinin (HA) glycoprotein. These substitutions can affect virus receptor-binding and alter virus antigenicity, thereby, obfuscating the choice of egg-propagated viruses for development into candidate vaccine viruses. To evaluate the effects of egg-adaptive substitutions seen in H3N2 vaccine viruses on sialic acid receptor-binding, we carried out quantitative measurement of virus receptor-binding using surface biolayer interferometry with haemagglutination inhibition (HI) assays to correlate changes in receptor avidity with antigenic properties. Included in these studies was a panel of H3N2 viruses generated by reverse genetics containing substitutions seen in recent egg-propagated vaccine viruses and corresponding cell culture-propagated wild-type viruses. These assays provide a quantitative approach to investigating the importance of individual amino acid substitutions in influenza receptor-binding. Results show that viruses with egg-adaptive HA substitutions R156Q, S219Y, and I226N, have increased binding avidity to α2,3-linked receptor-analogues and decreased binding avidity to α2,6-linked receptor-analogues. No measurable binding was detected for the viruses with amino acid substitution combination 156Q+219Y and receptor-binding increased in viruses where egg-adaptation mutations were introduced into cell culture-propagated virus. Substitutions at positions 156 and 190 appeared to be primarily responsible for low reactivity in HI assays with post-infection ferret antisera raised against 2012-2013 season H3N2 viruses. Egg-adaptive substitutions at position 186 caused substantial differences in binding avidity with an insignificant effect on antigenicity.

Dysregulated expression of MIG/CXCL9, IP-10/CXCL10 and CXCL16 and their receptors in systemic sclerosis

PubMed Central

2011-01-01

Introduction Systemic sclerosis (SSc) is characterized by fibrosis and microvascular abnormalities including dysregulated angiogenesis. Chemokines, in addition to their chemoattractant properties, have the ability to modulate angiogenesis. Chemokines lacking the enzyme-linked receptor (ELR) motif, such as monokine induced by interferon-γ (IFN-γ) (MIG/CXCL9) and IFN-inducible protein 10 (IP-10/CXCL10), inhibit angiogenesis by binding CXCR3. In addition, CXCL16 promotes angiogenesis by binding its unique receptor CXCR6. In this study, we determined the expression of these chemokines and receptors in SSc skin and serum. Methods Immunohistology and enzyme-linked immunosorbent assays (ELISAs) were used to determine chemokine and chemokine receptor expression in the skin and serum, respectively, of SSc and normal patients. Endothelial cells (ECs) were isolated from SSc skin biopsies and chemokine and chemokine receptor expression was determined by quantitative PCR and immunofluorescence staining. Results Antiangiogenic IP-10/CXCL10 and MIG/CXCL9 were elevated in SSc serum and highly expressed in SSc skin. However, CXCR3, the receptor for these chemokines, was decreased on ECs in SSc vs. normal skin. CXCL16 was elevated in SSc serum and increased in SSc patients with early disease, pulmonary arterial hypertension, and those that died during the 36 months of the study. In addition, its receptor CXCR6 was overexpressed on ECs in SSc skin. At the mRNA and protein levels, CXCR3 was decreased while CXCR6 was increased on SSc ECs vs. human microvascular endothelial cells (HMVECs). Conclusions These results show that while the expression of MIG/CXCL9 and IP-10/CXCL10 are elevated in SSc serum, the expression of CXCR3 is downregulated on SSc dermal ECs. In contrast, CXCL16 and CXCR6 are elevated in SSc serum and on SSc dermal ECs, respectively. In all, these findings suggest angiogenic chemokine receptor expression is likely regulated in an effort to promote angiogenesis in SSc skin. PMID:21303517

Dietary modulators of peroxisome proliferator-activated receptors: implications for the prevention and treatment of metabolic syndrome.

PubMed

Guri, Amir J; Hontecillas, Raquel; Bassaganya-Riera, Josep

2008-01-01

In its simplest form, obesity is a state characterized by nutrient overabundance leading to hypertrophy of storage cells in white adipose tissue and the deposition of excess lipids into key metabolic regions, such as skeletal muscle and liver. Ever so steadily, this condition begins to manifest itself as progressive insulin resistance and thus ensues a myriad of other chronic diseases, such as type 2 diabetes, cardiovascular disease, and hypertension, which all fall into the realm of the metabolic syndrome. To offset imbalances in nutrient availability, however, it appears that nature has developed the peroxisome proliferator-activated receptors (PPARs), a family of endogenous lipid sensors that adeptly modulate our rates of macronutrient oxidation and regulate the systemic inflammatory response, which itself is tightly linked to the development of obesity-induced chronic disease. By understanding how PPARs alpha, delta and gamma act jointly to maintain metabolic homeostasis and reduce the chronic inflammation associated with obesity, we may one day discover that the machinery needed to defeat obesity and control the devastating consequences of the metabolic syndrome have been with us the entire time.

Binding-Site Compatible Fragment Growing Applied to the Design of β2-Adrenergic Receptor Ligands.

PubMed

Chevillard, Florent; Rimmer, Helena; Betti, Cecilia; Pardon, Els; Ballet, Steven; van Hilten, Niek; Steyaert, Jan; Diederich, Wibke E; Kolb, Peter

2018-02-08

Fragment-based drug discovery is intimately linked to fragment extension approaches that can be accelerated using software for de novo design. Although computers allow for the facile generation of millions of suggestions, synthetic feasibility is however often neglected. In this study we computationally extended, chemically synthesized, and experimentally assayed new ligands for the β 2 -adrenergic receptor (β 2 AR) by growing fragment-sized ligands. In order to address the synthetic tractability issue, our in silico workflow aims at derivatized products based on robust organic reactions. The study started from the predicted binding modes of five fragments. We suggested a total of eight diverse extensions that were easily synthesized, and further assays showed that four products had an improved affinity (up to 40-fold) compared to their respective initial fragment. The described workflow, which we call "growing via merging" and for which the key tools are available online, can improve early fragment-based drug discovery projects, making it a useful creative tool for medicinal chemists during structure-activity relationship (SAR) studies.

Risk factors for breast cancer by oestrogen receptor status: a population-based case-control study.

PubMed Central

Cooper, J. A.; Rohan, T. E.; Cant, E. L.; Horsfall, D. J.; Tilley, W. D.

1989-01-01

Data from a population-based case-control study conducted in Adelaide, South Australia, and involving 451 case-control pairs, were analysed to determine whether the associations of menstrual, reproductive, dietary and other factors with risk of breast cancer differed by oestrogen receptor (ER) status. Data on ER status were available for 380 cases. The proportion of tumours which were ER+ increased with age, and there was a higher proportion of ER+ tumours in post-menopausal than in premenopausal women. Both oral contraceptive use (P = 0.055) and cigarette smoking (P = 0.047) were associated with increased (unadjusted) risk of ER- cancer, while having little association with risk of ER+ cancer. Most dietary factors had little association with risk of either cancer type, the main exception being the reduction in risk of ER- breast cancer with increasing beta-carotene intake (P for trend = 0.017). In general, however, links with the factors examined were not strong enough to suggest different causal pathways for ER- and ER+ breast cancer. PMID:2757918

Gs-coupled GPCR signalling in AgRP neurons triggers sustained increase in food intake

PubMed Central

Nakajima, Ken-ichiro; Cui, Zhenzhong; Li, Chia; Meister, Jaroslawna; Cui, Yinghong; Fu, Ou; Smith, Adam S.; Jain, Shalini; Lowell, Bradford B.; Krashes, Michael J.; Wess, Jürgen

2016-01-01

Agouti-related peptide (AgRP) neurons of the hypothalamus play a key role in regulating food intake and body weight, by releasing three different orexigenic molecules: AgRP; GABA; and neuropeptide Y. AgRP neurons express various G protein-coupled receptors (GPCRs) with different coupling properties, including Gs-linked GPCRs. At present, the potential role of Gs-coupled GPCRs in regulating the activity of AgRP neurons remains unknown. Here we show that the activation of Gs-coupled receptors expressed by AgRP neurons leads to a robust and sustained increase in food intake. We also provide detailed mechanistic data linking the stimulation of this class of receptors to the observed feeding phenotype. Moreover, we show that this pathway is clearly distinct from other GPCR signalling cascades that are operative in AgRP neurons. Our data suggest that drugs able to inhibit this signalling pathway may become useful for the treatment of obesity. PMID:26743492

Characterization of B61, the ligand for the Eck receptor protein-tyrosine kinase.

PubMed

Shao, H; Pandey, A; O'Shea, K S; Seldin, M; Dixit, V M

1995-03-10

B61 was originally described as a novel secreted tumor necrosis factor-alpha-inducible gene product in endothelial cells (Holzman, L. B., Marks, R. M., and Dixit, V. M. (1990) Mol. Cell. Biol. 10, 5830-5838). It was recently discovered that soluble recombinant B61 could serve as a ligand for the Eck receptor protein-tyrosine kinase, a member of the Eph/Eck subfamily of receptor protein-tyrosine kinases (Bartley, T.D., Hunt, R. W., Welcher, A. A., Boyle, W. J., Parker, V. P., Lindberg, R. A., Lu, H. S., Colombero, A. M., Elliott, R. L., Guthrie, R. A., Holst, P. L., Skrine, J. D., Toso, R. J., Zhang, M., Fernandez, E., Trail, G., Yarnum, B., Yarden, Y., Hunter, T., and Fox, G. M. (1994) Nature 368, 558-560). We now show that B61 can also exist as a cell surface glycosylphosphatidyl-inositol-linked protein that is capable of activating the Eck receptor protein-tyrosine kinase, the first such report of a receptor protein-tyrosine kinase ligand that is glycosylphosphatidylinositol-linked. In addition, the expression patterns of B61 and Eck during mouse ontogeny were determined by in situ hybridization. Both were found to be highly expressed in the developing lung and gut, while Eck was preferentially expressed in the thymus. Finally, the gene for B61 was localized to a specific position on mouse chromosome 3 by interspecific back-cross analysis.

Cannabinoid Receptor 2 Participates in Amyloid-β Processing in a Mouse Model of Alzheimer's Disease but Plays a Minor Role in the Therapeutic Properties of a Cannabis-Based Medicine.

PubMed

Aso, Ester; Andrés-Benito, Pol; Carmona, Margarita; Maldonado, Rafael; Ferrer, Isidre

2016-01-01

The endogenous cannabinoid system represents a promising therapeutic target to modify neurodegenerative pathways linked to Alzheimer's disease (AD). The aim of the present study was to evaluate the specific contribution of CB2 receptor to the progression of AD-like pathology and its role in the positive effect of a cannabis-based medicine (1:1 combination of Δ9-tetrahidrocannabinol and cannabidiol) previously demonstrated to be beneficial in the AβPP/PS1 transgenic model of the disease. A new mouse strain was generated by crossing AβPP/PS1 transgenic mice with CB2 knockout mice. Results show that lack of CB2 exacerbates cortical Aβ deposition and increases the levels of soluble Aβ40. However, CB2 receptor deficiency does not affect the viability of AβPP/PS1 mice, does not accelerate their memory impairment, does not modify tau hyperphosphorylation in dystrophic neurites associated to Aβ plaques, and does not attenuate the positive cognitive effect induced by the cannabis-based medicine in these animals. These findings suggest a minor role for the CB2 receptor in the therapeutic effect of the cannabis-based medicine in AβPP/PS1 mice, but also constitute evidence of a link between CB2 receptor and Aβ processing.

The diabetes drug liraglutide reverses cognitive impairment in mice and attenuates insulin receptor and synaptic pathology in a non-human primate model of Alzheimer's disease.

PubMed

Batista, Andre F; Forny-Germano, Leticia; Clarke, Julia R; Lyra E Silva, Natalia M; Brito-Moreira, Jordano; Boehnke, Susan E; Winterborn, Andrew; Coe, Brian C; Lablans, Ann; Vital, Juliana F; Marques, Suelen A; Martinez, Ana Mb; Gralle, Matthias; Holscher, Christian; Klein, William L; Houzel, Jean-Christophe; Ferreira, Sergio T; Munoz, Douglas P; De Felice, Fernanda G

2018-05-01

Alzheimer's disease (AD) is a devastating neurological disorder that still lacks an effective treatment, and this has stimulated an intense pursuit of disease-modifying therapeutics. Given the increasingly recognized link between AD and defective brain insulin signaling, we investigated the actions of liraglutide, a glucagon-like peptide-1 (GLP-1) analog marketed for treatment of type 2 diabetes, in experimental models of AD. Insulin receptor pathology is an important feature of AD brains that impairs the neuroprotective actions of central insulin signaling. Here, we show that liraglutide prevented the loss of brain insulin receptors and synapses, and reversed memory impairment induced by AD-linked amyloid-β oligomers (AβOs) in mice. Using hippocampal neuronal cultures, we determined that the mechanism of neuroprotection by liraglutide involves activation of the PKA signaling pathway. Infusion of AβOs into the lateral cerebral ventricle of non-human primates (NHPs) led to marked loss of insulin receptors and synapses in brain regions related to memory. Systemic treatment of NHPs with liraglutide provided partial protection, decreasing AD-related insulin receptor, synaptic, and tau pathology in specific brain regions. Synapse damage and elimination are amongst the earliest known pathological changes and the best correlates of memory impairment in AD. The results illuminate mechanisms of neuroprotection by liraglutide, and indicate that GLP-1 receptor activation may be harnessed to protect brain insulin receptors and synapses in AD. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Therapeutic Utility of Non-Peptidic CRF1 Receptor Antagonists in Anxiety, Depression, and Stress-Related Disorders: Evidence from Animal Models

PubMed Central

Kehne, John H.; Cain, Christopher K.

2012-01-01

Adaptive responding to threatening stressors is of fundamental importance for survival. Dysfunctional hyperactivation of corticotropin releasing factor type-1 (CRF1) receptors in stress response system pathways is linked to stress-related psychopathology and CRF1 receptor antagonists (CRAs) have been proposed as novel therapeutic agents. CRA effects in diverse animal models of stress that detect anxiolytics and/or antidepressants are reviewed, with the goal of evaluating their potential therapeutic utility in depression, anxiety, and other stress-related disorders. CRAs have a distinct phenotype in animals that has similarities to, and differences from, those of classic antidepressants and anxiolytics. CRAs are generally behaviorally silent, indicating that CRF1 receptors are normally in a state of low basal activation. CRAs reduce stressor-induced HPA axis activation by blocking pituitary and possibly brain CRF1 receptors which may ameliorate chronic stress-induced pathology. In animal models sensitive to anxiolytics and/or antidepressants, CRAs are generally more active in those with high stress levels, conditions which may maximize CRF1 receptor hyperactivation. Clinically, CRAs have demonstrated good tolerability and safety, but have thus far lacked compelling efficacy in major depressive disorder, generalized anxiety disorder, or irritable bowel syndrome. CRAs may be best suited for disorders in which stressors clearly contribute to the underlying pathology (e.g. posttraumatic stress disorder, early life trauma, withdrawal/abstinence from addictive substances), though much work is needed to explore these possibilities. An evolving literature exploring the genetic, developmental and environmental factors linking CRF1 receptor dysfunction to stress-related psychopathology is discussed in the context of improving the translational value of current animal models. PMID:20826181

Links between DRD4, Executive Attention, and Alphabetic Skills in a Nonclinical Sample

ERIC Educational Resources Information Center

Kegel, Cornelia A. T.; Bus, Adriana G.

2013-01-01

Background: The dopamine D4 receptor gene (DRD4) has been linked to attention deficit hyperactivity disorder (ADHD) and reading disorders. In this study, we examined whether diminished anticipatory dopamine cell firing--typical of the long variant of the DRD4 allele--is related to emergent and advanced alphabetic skills, and whether executive…

N-linked glycan truncation causes enhanced clearance of plasma-derived von Willebrand factor.

PubMed

O'Sullivan, J M; Aguila, S; McRae, E; Ward, S E; Rawley, O; Fallon, P G; Brophy, T M; Preston, R J S; Brady, L; Sheils, O; Chion, A; O'Donnell, J S

2016-12-01

Essentials von Willebrands factor (VWF) glycosylation plays a key role in modulating in vivo clearance. VWF glycoforms were used to examine the role of specific glycan moieties in regulating clearance. Reduction in sialylation resulted in enhanced VWF clearance through asialoglycoprotein receptor. Progressive VWF N-linked glycan trimming resulted in increased macrophage-mediated clearance. Click to hear Dr Denis discuss clearance of von Willebrand factor in a free presentation from the ISTH Academy SUMMARY: Background Enhanced von Willebrand factor (VWF) clearance is important in the etiology of both type 1 and type 2 von Willebrand disease (VWD). In addition, previous studies have demonstrated that VWF glycans play a key role in regulating in vivo clearance. However, the molecular mechanisms underlying VWF clearance remain poorly understood. Objective To define the molecular mechanisms through which VWF N-linked glycan structures influence in vivo clearance. Methods By use of a series of exoglycosidases, different plasma-derived VWF (pd-VWF) glycoforms were generated. In vivo clearance of these glycoforms was then assessed in VWF -/- mice in the presence or absence of inhibitors of asialoglycoprotein receptor (ASGPR), or following clodronate-induced macrophage depletion. Results Reduced amounts of N-linked and O-linked sialylation resulted in enhanced pd-VWF clearance modulated via ASGPR. In addition to this role of terminal sialylation, we further observed that progressive N-linked glycan trimming also resulted in markedly enhanced VWF clearance. Furthermore, these additional N-linked glycan effects on clearance were ASGPR-independent, and instead involved enhanced macrophage clearance that was mediated, at least in part, through LDL receptor-related protein 1. Conclusion The carbohydrate determinants expressed on VWF regulate susceptibility to proteolysis by ADAMTS-13. In addition, our findings now further demonstrate that non-sialic acid carbohydrate determinants expressed on VWF also play an unexpectedly important role in modulating in vivo clearance through both hepatic ASGPR-dependent and macrophage-dependent pathways. In addition, these data further support the hypothesis that variation in VWF glycosylation may be important in the pathophysiology underlying type 1C VWD. © 2016 International Society on Thrombosis and Haemostasis.

Smad3 allostery links TGF-β receptor kinase activation to transcriptional control

PubMed Central

Qin, Bin Y.; Lam, Suvana S.; Correia, John J.; Lin, Kai

2002-01-01

Smad3 transduces the signals of TGF-βs, coupling transmembrane receptor kinase activation to transcriptional control. The membrane-associated molecule SARA (Smad Anchor for Receptor Activation) recruits Smad3 for phosphorylation by the receptor kinase. Upon phosphorylation, Smad3 dissociates from SARA and enters the nucleus, in which its transcriptional activity can be repressed by Ski. Here, we show that SARA and Ski recognize specifically the monomeric and trimeric forms of Smad3, respectively. Thus, trimerization of Smad3, induced by phosphorylation, simultaneously activates the TGF-β signal by driving Smad3 dissociation from SARA and sets up the negative feedback mechanism by Ski. Structural models of the Smad3/SARA/receptor kinase complex and Smad3/Ski complex provide insights into the molecular basis of regulation. PMID:12154125

Six commercially available angiotensin II AT1 receptor antibodies are non-specific.

PubMed

Benicky, Julius; Hafko, Roman; Sanchez-Lemus, Enrique; Aguilera, Greti; Saavedra, Juan M

2012-11-01

Commercially available Angiotensin II AT1 receptor antibodies are widely employed for receptor localization and quantification, but they have not been adequately validated. In this study, six commercially available AT1 receptor antibodies were characterized by established criteria: sc-1173 and sc-579 from Santa Cruz Biotechnology, Inc., AAR-011 from Alomone Labs, Ltd., AB15552 from Millipore, and ab18801 and ab9391 from Abcam. The immunostaining patterns observed were different for every antibody tested, and were unrelated to the presence or absence of AT1 receptors. The antibodies detected a 43 kDa band in western blots, corresponding to the predicted size of the native AT1 receptor. However, identical bands were observed in wild-type mice and in AT1A knock-out mice not expressing the target protein. Moreover, immunoreactivity detected in rat hypothalamic 4B cells not expressing AT1 receptors or transfected with AT1A receptor construct was identical, as revealed by western blotting and immunocytochemistry in cultured 4B cells. Additional prominent immunoreactive bands above and below 43 kDa were observed by western blotting in extracts from tissues of AT1A knock-out and wild-type mice and in 4B cells with or without AT1 receptor expression. In all cases, the patterns of immunoreactivity were independent of the AT1 receptor expression and different for each antibody studied. We conclude that, in our experimental setup, none of the commercially available AT1 receptor antibodies tested met the criteria for specificity and that competitive radioligand binding remains the only reliable approach to study AT1 receptor physiology in the absence of full antibody characterization.

Six Commercially Available Angiotensin II AT1 Receptor Antibodies are Non-specific

PubMed Central

Benicky, Julius; Hafko, Roman; Sanchez-Lemus, Enrique; Aguilera, Greti

2012-01-01

Commercially available Angiotensin II AT1 receptor antibodies are widely employed for receptor localization and quantification, but they have not been adequately validated. In this study, six commercially available AT1 receptor antibodies were characterized by established criteria: sc-1173 and sc-579 from Santa Cruz Biotechnology, Inc., AAR-011 from Alomone Labs, Ltd., AB15552 from Millipore, and ab18801 and ab9391 from Abcam. The immunostaining patterns observed were different for every antibody tested, and were unrelated to the presence or absence of AT1 receptors. The antibodies detected a 43 kDa band in western blots, corresponding to the predicted size of the native AT1 receptor. However, identical bands were observed in wild-type mice and in AT1A knock-out mice not expressing the target protein. Moreover, immunoreactivity detected in rat hypothalamic 4B cells not expressing AT1 receptors or transfected with AT1A receptor construct was identical, as revealed by western blotting and immunocytochemistry in cultured 4B cells. Additional prominent immunoreactive bands above and below 43 kDa were observed by western blotting in extracts from tissues of AT1A knock-out and wild-type mice and in 4B cells with or without AT1 receptor expression. In all cases, the patterns of immunoreactivity were independent of the AT1 receptor expression and different for each antibody studied. We conclude that, in our experimental setup, none of the commercially available AT1 receptor antibodies tested met the criteria for specificity and that competitive radioligand binding remains the only reliable approach to study AT1 receptor physiology in the absence of full antibody characterization. PMID:22843099

Remote Control of Neuronal Signaling

PubMed Central

Rogan, Sarah C.

2011-01-01

A significant challenge for neuroscientists is to determine how both electrical and chemical signals affect the activity of cells and circuits and how the nervous system subsequently translates that activity into behavior. Remote, bidirectional manipulation of those signals with high spatiotemporal precision is an ideal approach to addressing that challenge. Neuroscientists have recently developed a diverse set of tools that permit such experimental manipulation with varying degrees of spatial, temporal, and directional control. These tools use light, peptides, and small molecules to primarily activate ion channels and G protein-coupled receptors (GPCRs) that in turn activate or inhibit neuronal firing. By monitoring the electrophysiological, biochemical, and behavioral effects of such activation/inhibition, researchers can better understand the links between brain activity and behavior. Here, we review the tools that are available for this type of experimentation. We describe the development of the tools and highlight exciting in vivo data. We focus primarily on designer GPCRs (receptors activated solely by synthetic ligands, designer receptors exclusively activated by designer drugs) and microbial opsins (e.g., channelrhodopsin-2, halorhodopsin, Volvox carteri channelrhodopsin) but also describe other novel techniques that use orthogonal receptors, caged ligands, allosteric modulators, and other approaches. These tools differ in the direction of their effect (activation/inhibition, hyperpolarization/depolarization), their onset and offset kinetics (milliseconds/minutes/hours), the degree of spatial resolution they afford, and their invasiveness. Although none of these tools is perfect, each has advantages and disadvantages, which we describe, and they are all still works in progress. We conclude with suggestions for improving upon the existing tools. PMID:21415127

The Concise Guide to PHARMACOLOGY 2015/16: Overview.

PubMed

Alexander, Stephen Ph; Kelly, Eamonn; Marrion, Neil; Peters, John A; Benson, Helen E; Faccenda, Elena; Pawson, Adam J; Sharman, Joanna L; Southan, Christopher; Buneman, O Peter; Catterall, William A; Cidlowski, John A; Davenport, Anthony P; Fabbro, Doriano; Fan, Grace; McGrath, John C; Spedding, Michael; Davies, Jamie A

2015-12-01

The Concise Guide to PHARMACOLOGY 2015/16 provides concise overviews of the key properties of over 1750 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.13347/full. This compilation of the major pharmacological targets is divided into eight areas of focus: G protein-coupled receptors, ligand-gated ion channels, voltage-gated ion channels, other ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The Concise Guide is published in landscape format in order to facilitate comparison of related targets. It is a condensed version of material contemporary to late 2015, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in the previous Guides to Receptors & Channels and the Concise Guide to PHARMACOLOGY 2013/14. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and GRAC and provides a permanent, citable, point-in-time record that will survive database updates. © 2015 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of The British Pharmacological Society.

Regulation of Ion Channels by Pyridine Nucleotides

PubMed Central

Kilfoil, Peter J.; Tipparaju, Srinivas M.; Barski, Oleg A.; Bhatnagar, Aruni

2014-01-01

Recent research suggests that in addition to their role as soluble electron carriers, pyridine nucleotides [NAD(P)(H)] also regulate ion transport mechanisms. This mode of regulation seems to have been conserved through evolution. Several bacterial ion–transporting proteins or their auxiliary subunits possess nucleotide-binding domains. In eukaryotes, the Kv1 and Kv4 channels interact with pyridine nucleotide–binding β-subunits that belong to the aldo-keto reductase superfamily. Binding of NADP+ to Kvβ removes N-type inactivation of Kv currents, whereas NADPH stabilizes channel inactivation. Pyridine nucleotides also regulate Slo channels by interacting with their cytosolic regulator of potassium conductance domains that show high sequence homology to the bacterial TrkA family of K+ transporters. These nucleotides also have been shown to modify the activity of the plasma membrane KATP channels, the cystic fibrosis transmembrane conductance regulator, the transient receptor potential M2 channel, and the intracellular ryanodine receptor calcium release channels. In addition, pyridine nucleotides also modulate the voltage-gated sodium channel by supporting the activity of its ancillary subunit—the glycerol-3-phosphate dehydrogenase-like protein. Moreover, the NADP+ metabolite, NAADP+, regulates intracellular calcium homeostasis via the 2-pore channel, ryanodine receptor, or transient receptor potential M2 channels. Regulation of ion channels by pyridine nucleotides may be required for integrating cell ion transport to energetics and for sensing oxygen levels or metabolite availability. This mechanism also may be an important component of hypoxic pulmonary vasoconstriction, memory, and circadian rhythms, and disruption of this regulatory axis may be linked to dysregulation of calcium homeostasis and cardiac arrhythmias. PMID:23410881

Androgens and esophageal cancer: What do we know?

PubMed

Sukocheva, Olga A; Li, Bin; Due, Steven L; Hussey, Damian J; Watson, David I

2015-05-28

Significant disparities exist between genders for the development and progression of several gastro-intestinal (GI) diseases including cancer. Differences in incidence between men vs women for colon, gastric and hepatocellular cancers suggest a role for steroid sex hormones in regulation of GI carcinogenesis. Involvement of intrinsic gender-linked mechanisms is also possible for esophageal adenocarcinoma as its incidence is disproportionally high among men. However, the cause of the observed gender differences and the potential role of androgens in esophageal carcinogenesis remains unclear, even though the cancer-promoting role of androgen receptors (AR) shown in other cancers such as prostate and bladder suggests this aspect warrants exploration. Several studies have demonstrated expression of ARs in esophageal cancer. However, only one study has suggested a potential link between AR signaling and outcome - poorer prognosis. Two groups have analyzed data from cohorts with prostate cancer and one of these found a decreased incidence of esophageal squamous and adenocarcinoma after androgen deprivation therapy. However, very limited information is available about the effects of androgen and AR-initiated signaling on esophageal cancer cell growth in vitro and in vivo. Possible mechanisms for androgens/AR involvement in the regulation of esophageal cancer growth are considered, and the potential use of AR as a prognostic factor and clinical target is highlighted, although insufficient evidence is available to support clinical trials of novel therapies. As esophageal adenocarcinoma is a gender linked cancer with a large male predominance further studies are warranted to clarify the role of androgens and ARs in shaping intracellular signaling and genomic responses in esophageal cancer.

Gastrin Receptor-Avid Peptide Conjugates

DOEpatents

Hoffman, Timothy J.; Volkert, Wynn A.; Li, Ning; Sieckman, Gary; Higginbotham, Chrys-Ann

2005-07-26

A compound for use as a therapeutic or diagnostic radiopharmaceutical includes a group capable of complexing a medically useful metal attached to a moiety which is capable of binding to a gastrin releasing peptide receptor. A method for treating a subject having a neoplastic disease includes administering to the subject an effective amount of a radiopharmaceutical having a metal chelated with a chelating group attached to a moiety capable of binding to a gastrin releasing peptide receptor expressed on tumor cells with subsequent internalization inside of the cell. A method of forming a therapeutic or diagnostic compound includes reacting a metal synthon with a chelating group covalently linked with a moiety capable of binding a gastrin releasing peptide receptor.

Gastrin receptor-avid peptide conjugates

DOEpatents

Hoffman, Timothy J.; Volkert, Wynn A.; Li, Ning; Sieckman, Gary; Higginbotham, C. A.

2001-01-01

A compound for use as a therapeutic or diagnostic radiopharmaceutical includes a group capable of complexing a medically useful metal attached to a moiety which is capable of binding to a gastrin releasing peptide receptor. A method for treating a subject having a neoplastic disease includes administering to the subject an effective amount of a radiopharmaceutical having a metal chelated with a chelating group attached to a moiety capable of binding to a gastrin releasing peptide receptor expressed on tumor cells with subsequent internalization inside of the cell. A method of forming a therapeutic or diagnostic compound includes reacting a metal synthon with a chelating group covalently linked with a moiety capable of binding a gastrin releasing peptide receptor.

Gastrin receptor-avid peptide conjugates

DOEpatents

Hoffman, Timothy J.; Volkert, Wynn A.; Sieckman, Gary; Smith, Charles J.; Gali, Hariprasad

2006-06-13

A compound for use as a therapeutic or diagnostic radiopharmaceutical includes a group capable of complexing a medically useful metal attached to a moiety which is capable of binding to a gastrin releasing peptide receptor. A method for treating a subject having a neoplastic disease includes administering to the subject an effective amount of a radiopharmaceutical having a metal chelated with a chelating group attached to a-moiety capable of binding to a gastrin releasing peptide receptor expressed on tumor cells with subsequent internalization inside of the cell. A method of forming a therapeutic or diagnostic compound includes reacting a metal synthon with a chelating group covalently linked with a moiety capable of binding a gastrin releasing peptide receptor.

Gastrin receptor-avid peptide conjugates

DOEpatents

Hoffman, Timothy J.; Volkert, Wynn A.; Li, Ning; Sieckman, Gary; Higginbotham, Chrys-Ann

2006-12-12

A compound for use as a therapeutic or diagnostic radiopharmaceutical includes a group capable of complexing a medically useful metal attached to a moiety which is capable of binding to a gastrin releasing peptide receptor. A method for treating a subject having a neoplastic disease includes administering to the subject an effective amount of a radiopharmaceutical having a metal chelated with a chelating group attached to a moiety capable of binding to a gastrin releasing peptide receptor expressed on tumor cells with subsequent internalization inside of the cell. A method of forming a therapeutic or diagnostic compound includes reacting a metal synthon with a chelating group covalently linked with a moiety capable of binding a gastrin releasing peptide receptor.

Sex Differences in Serotonin 1 Receptor Binding in Rat Brain

NASA Astrophysics Data System (ADS)

Fischette, Christine T.; Biegon, Anat; McEwen, Bruce S.

1983-10-01

Male and female rats exhibit sex differences in binding by serotonin 1 receptors in discrete areas of the brain, some of which have been implicated in the control of ovulation and of gonadotropin release. The sex-specific changes in binding, which occur in response to the same hormonal (estrogenic) stimulus, are due to changes in the number of binding sites. Castration alone also affects the number of binding sites in certain areas. The results lead to the conclusion that peripheral hormones modulate binding by serotonin 1 receptors. The status of the serotonin receptor system may affect the reproductive capacity of an organism and may be related to sex-linked emotional disturbances in humans.

Beta-Adrenergic Receptor Activation during Distinct Patterns of Stimulation Critically Modulates the PKA-Dependence of LTP in the Mouse Hippocampus

ERIC Educational Resources Information Center

Gelinas, Jennifer N.; Tenorio, Gustavo; Lemon, Neal; Abel, Ted; Nguyen, Peter V.

2008-01-01

Activation of Beta-adrenergic receptors (Beta-ARs) enhances hippocampal memory consolidation and long-term potentiation (LTP), a likely mechanism for memory storage. One signaling pathway linked to Beta-AR activation is the cAMP-PKA pathway. PKA is critical for the consolidation of hippocampal long-term memory and for the expression of some forms…

Symptoms of Attention-Deficit/Hyperactivity Disorder in Down Syndrome: Effects of the Dopamine Receptor D4 Gene

ERIC Educational Resources Information Center

Mason, Gina Marie; Spanó, Goffredina; Edgin, Jamie

2015-01-01

This study examined individual differences in ADHD symptoms and executive function (EF) in children with Down syndrome (DS) in relation to the dopamine receptor D4 (DRD4) gene, a gene often linked to ADHD in people without DS. Participants included 68 individuals with DS (7-21 years), assessed through laboratory tasks, caregiver reports, and…

Identification of the GnRH-(1-5) Receptor and Signaling Pathway

DTIC Science & Technology

2013-03-22

Coimmunoprecipitation DAG Diacylglycerol DNA Deoxyribonucleic Acid DR Aspartic Acid/ Aspargine Motif ED Embryonic Day ELISA Enzyme -Linked...candidate GnRH-(1-5) receptors by using a high-throughput enzyme fragment complementation assay (DiscoveRx, Fremont, CA). The results from the assay...for an orphan GPCR is of paramount significance since there are greater than 100 orphan GPCRs considered potential targets for the development of

Appropriate polarization following pharmacological rescue of V2 vasopressin receptors encoded by X-linked nephrogenic diabetes insipidus alleles involves a conformation of the receptor that also attains mature glycosylation.

PubMed

Tan, Christopher M; Nickols, Hilary Highfield; Limbird, Lee E

2003-09-12

To understand the mechanisms of G protein-coupled receptor delivery and steady state localization, we examined the trafficking itineraries of wild type (WT) and mutant V2 vasopressin receptors (V2Rs) in polarized Madin-Darby canine kidney II (MDCK II) cells and in COS M6 cells; the mutant V2Rs represent selected alleles responsible for X-linked nephrogenic diabetes insipidus. The WT V2R is localized on the plasma membrane and mediates arginine vasopressin (AVP)-stimulated cAMP accumulation, whereas the clinically relevant V2R mutants, L292P V2R, Delta V278 V2R, and R337X V2R, are retained intracellularly, are insensitive to extracellularly added AVP, and are not processed beyond initial immature glycosylation, manifest by their endoglycosidase H sensitivity. Reduced temperature and pharmacological, but not chemical, strategies rescue mutant V2Rs to the cell surface of COS M6 cells; surface rescue of L292P V2R and R337X V2R, but not of Delta V278 V2R, parallels acquisition of AVP-stimulated cAMP production. Pharmacological rescue of the L292P or R337X V2R by incubation with the membrane-permeant V2R antagonist, SR121463B, leads to a mature glycosylated form of the receptor that achieves localization on the basolateral surface of polarized MDCK II cells indistinguishable from that of the WT V2R. Surprisingly, however, the immature form of the mutant L292P V2R escapes to the apical, but not basolateral, surface of polarized MDCK II cells, even in the absence of SR121463B. These findings are consistent with the interpretation that the receptor conformation that allows appropriate processing through the N-linked glycosylation pathway is also essential for V2R targeting to the appropriate surface of polarized epithelial cells.

Opioid receptor trafficking and interaction in nociceptors

PubMed Central

Zhang, X; Bao, L; Li, S

2015-01-01

Opiate analgesics such as morphine are often used for pain therapy. However, antinociceptive tolerance and dependence may develop with long-term use of these drugs. It was found that μ-opioid receptors can interact with δ-opioid receptors, and morphine antinociceptive tolerance can be reduced by blocking δ-opioid receptors. Recent studies have shown that μ- and δ-opioid receptors are co-expressed in a considerable number of small neurons in the dorsal root ganglion. The interaction of μ-opioid receptors with δ-opioid receptors in the nociceptive afferents is facilitated by the stimulus-induced cell-surface expression of δ-opioid receptors, and contributes to morphine tolerance. Further analysis of the molecular, cellular and neural circuit mechanisms that regulate the trafficking and interaction of opioid receptors and related signalling molecules in the pain pathway would help to elucidate the mechanism of opiate analgesia and improve pain therapy. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2 PMID:24611685

Theoretical and Computational Studies of Peptides and Receptors of the Insulin Family

PubMed Central

Vashisth, Harish

2015-01-01

Synergistic interactions among peptides and receptors of the insulin family are required for glucose homeostasis, normal cellular growth and development, proliferation, differentiation and other metabolic processes. The peptides of the insulin family are disulfide-linked single or dual-chain proteins, while receptors are ligand-activated transmembrane glycoproteins of the receptor tyrosine kinase (RTK) superfamily. Binding of ligands to the extracellular domains of receptors is known to initiate signaling via activation of intracellular kinase domains. While the structure of insulin has been known since 1969, recent decades have seen remarkable progress on the structural biology of apo and liganded receptor fragments. Here, we review how this useful structural information (on ligands and receptors) has enabled large-scale atomically-resolved simulations to elucidate the conformational dynamics of these biomolecules. Particularly, applications of molecular dynamics (MD) and Monte Carlo (MC) simulation methods are discussed in various contexts, including studies of isolated ligands, apo-receptors, ligand/receptor complexes and intracellular kinase domains. The review concludes with a brief overview and future outlook for modeling and computational studies in this family of proteins. PMID:25680077

Crystal structures of the M 1 and M 4 muscarinic acetylcholine receptors

DOE PAGES

Thal, David M.; Sun, Bingfa; Feng, Dan; ...

2016-03-09

Muscarinic M1–M5 acetylcholine receptors are G-protein-coupled receptors that regulate many vital functions of the central and peripheral nervous systems. In particular, the M1 and M4 receptor subtypes have emerged as attractive drug targets for treatments of neurological disorders, such as Alzheimer’s disease and schizophrenia, but the high conservation of the acetylcholine-binding pocket has spurred current research into targeting allosteric sites on these receptors. In this paper, we report the crystal structures of the M1 and M4 muscarinic receptors bound to the inverse agonist, tiotropium. Comparison of these structures with each other, as well as with the previously reported M2 andmore » M3 receptor structures, reveals differences in the orthosteric and allosteric binding sites that contribute to a role in drug selectivity at this important receptor family. Finally, we also report identification of a cluster of residues that form a network linking the orthosteric and allosteric sites of the M4 receptor, which provides new insight into how allosteric modulation may be transmitted between the two spatially distinct domains.« less

Crystal structures of the M 1 and M 4 muscarinic acetylcholine receptors

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

Thal, David M.; Sun, Bingfa; Feng, Dan

Muscarinic M1–M5 acetylcholine receptors are G-protein-coupled receptors that regulate many vital functions of the central and peripheral nervous systems. In particular, the M1 and M4 receptor subtypes have emerged as attractive drug targets for treatments of neurological disorders, such as Alzheimer’s disease and schizophrenia, but the high conservation of the acetylcholine-binding pocket has spurred current research into targeting allosteric sites on these receptors. In this paper, we report the crystal structures of the M1 and M4 muscarinic receptors bound to the inverse agonist, tiotropium. Comparison of these structures with each other, as well as with the previously reported M2 andmore » M3 receptor structures, reveals differences in the orthosteric and allosteric binding sites that contribute to a role in drug selectivity at this important receptor family. Finally, we also report identification of a cluster of residues that form a network linking the orthosteric and allosteric sites of the M4 receptor, which provides new insight into how allosteric modulation may be transmitted between the two spatially distinct domains.« less

A mutation in the insulin receptor gene that impairs transport of the receptor to the plasma membrane and causes insulin-resistant diabetes.

PubMed Central

Accili, D; Frapier, C; Mosthaf, L; McKeon, C; Elbein, S C; Permutt, M A; Ramos, E; Lander, E; Ullrich, A; Taylor, S I

1989-01-01

Insulin binds to a receptor on the cell surface, thereby triggering a biological response within the target cell. Mutations in the insulin receptor gene can render the cell resistant to the biological action of insulin. We have studied a family in which two sisters have a genetic form of insulin-resistant diabetes mellitus. The technique of homozygosity mapping has been used to demonstrate that the mutation causing diabetes in this consanguineous family is genetically linked to the insulin receptor gene. The two insulin-resistant sisters are homozygous for a mutation encoding substitution of valine for phenylalanine at position 382 in the alpha-subunit of the insulin receptor. Transfection of mutant insulin receptor cDNA into NIH3T3 cells demonstrated that the Val382 mutation impaired post-translational processing and retarded transport of the insulin receptor to the plasma membrane. Thus, the mutation causes insulin resistance by decreasing the number of insulin receptors on the surface of the patients' cells. Images PMID:2573522

Increased accuracy of ligand sensing by receptor diffusion on cell surface

NASA Astrophysics Data System (ADS)

Aquino, Gerardo; Endres, Robert G.

2010-10-01

The physical limit with which a cell senses external ligand concentration corresponds to the perfect absorber, where all ligand particles are absorbed and overcounting of same ligand particles does not occur. Here, we analyze how the lateral diffusion of receptors on the cell membrane affects the accuracy of sensing ligand concentration. Specifically, we connect our modeling to neurotransmission in neural synapses where the diffusion of glutamate receptors is already known to refresh synaptic connections. We find that receptor diffusion indeed increases the accuracy of sensing for both the glutamate α -Amino-3-hydroxy-5-Methyl-4-isoxazolePropionic Acid (AMPA) and N -Methyl-D-aspartic Acid (NMDA) receptor, although the NMDA receptor is overall much noisier. We propose that the difference in accuracy of sensing of the two receptors can be linked to their different roles in neurotransmission. Specifically, the high accuracy in sensing glutamate is essential for the AMPA receptor to start membrane depolarization, while the NMDA receptor is believed to work in a second stage as a coincidence detector, involved in long-term potentiation and memory.

Adaptor protein SH2-B linking receptor-tyrosine kinase and Akt promotes adipocyte differentiation by regulating peroxisome proliferator-activated receptor gamma messenger ribonucleic acid levels.

PubMed

Yoshiga, Daigo; Sato, Naoichi; Torisu, Takehiro; Mori, Hiroyuki; Yoshida, Ryoko; Nakamura, Seiji; Takaesu, Giichi; Kobayashi, Takashi; Yoshimura, Akihiko

2007-05-01

Adipocyte differentiation is regulated by insulin and IGF-I, which transmit signals by activating their receptor tyrosine kinase. SH2-B is an adaptor protein containing pleckstrin homology and Src homology 2 (SH2) domains that have been implicated in insulin and IGF-I receptor signaling. In this study, we found a strong link between SH2-B levels and adipogenesis. The fat mass and expression of adipogenic genes including peroxisome proliferator-activated receptor gamma (PPARgamma) were reduced in white adipose tissue of SH2-B-/- mice. Reduced adipocyte differentiation of SH2-B-deficient mouse embryonic fibroblasts (MEFs) was observed in response to insulin and dexamethasone, whereas retroviral SH2-B overexpression enhanced differentiation of 3T3-L1 preadipocytes to adipocytes. SH2-B overexpression enhanced mRNA level of PPARgamma in 3T3-L1 cells, whereas PPARgamma levels were reduced in SH2-B-deficient MEFs in response to insulin. SH2-B-mediated up-regulation of PPARgamma mRNA was blocked by a phosphatidylinositol 3-kinase inhibitor, but not by a MAPK kinase inhibitor. Insulin-induced Akt activation and the phosphorylation of forkhead transcription factor (FKHR/Foxo1), a negative regulator of PPARgamma transcription, were up-regulated by SH2-B overexpression, but reduced in SH2-B-deficient MEFs. These data indicate that SH2-B is a key regulator of adipogenesis both in vivo and in vitro by regulating the insulin/IGF-I receptor-Akt-Foxo1-PPARgamma pathway.

Vasoactive intestinal peptide-null mice demonstrate enhanced sweet taste preference, dysglycemia, and reduced taste bud leptin receptor expression.

PubMed

Martin, Bronwen; Shin, Yu-Kyong; White, Caitlin M; Ji, Sunggoan; Kim, Wook; Carlson, Olga D; Napora, Joshua K; Chadwick, Wayne; Chapter, Megan; Waschek, James A; Mattson, Mark P; Maudsley, Stuart; Egan, Josephine M

2010-05-01

It is becoming apparent that there is a strong link between taste perception and energy homeostasis. Recent evidence implicates gut-related hormones in taste perception, including glucagon-like peptide 1 and vasoactive intestinal peptide (VIP). We used VIP knockout mice to investigate VIP's specific role in taste perception and connection to energy regulation. Body weight, food intake, and plasma levels of multiple energy-regulating hormones were measured and pancreatic morphology was determined. In addition, the immunocytochemical profile of taste cells and gustatory behavior were examined in wild-type and VIP knockout mice. VIP knockout mice demonstrate elevated plasma glucose, insulin, and leptin levels, with no islet beta-cell number/topography alteration. VIP and its receptors (VPAC1, VPAC2) were identified in type II taste cells of the taste bud, and VIP knockout mice exhibit enhanced taste preference to sweet tastants. VIP knockout mouse taste cells show a significant decrease in leptin receptor expression and elevated expression of glucagon-like peptide 1, which may explain sweet taste preference of VIP knockout mice. This study suggests that the tongue can play a direct role in modulating energy intake to correct peripheral glycemic imbalances. In this way, we could view the tongue as a sensory mechanism that is bidirectionally regulated and thus forms a bridge between available foodstuffs and the intricate hormonal balance in the animal itself.

Structure of human Aichi virus and implications for receptor binding.

PubMed

Zhu, Ling; Wang, Xiangxi; Ren, Jingshan; Kotecha, Abhay; Walter, Thomas S; Yuan, Shuai; Yamashita, Teruo; Tuthill, Tobias J; Fry, Elizabeth E; Rao, Zihe; Stuart, David I

2016-09-05

Aichi virus (AiV), an unusual and poorly characterized picornavirus, classified in the genus Kobuvirus, can cause severe gastroenteritis and deaths in children below the age of five years, especially in developing countries 1,2 . The seroprevalence of AiV is approximately 60% in children under the age of ten years and reaches 90% later in life 3,4 . There is no available vaccine or effective antiviral treatment. Here, we describe the structure of AiV at 3.7 Å. This first high-resolution structure for a kobuvirus is intermediate between those of the enteroviruses and cardioviruses, with a shallow, narrow depression bounded by the prominent VP0 CD loops (linking the C and D strands of the β-barrel), replacing the depression known as the canyon, frequently the site of receptor attachment in enteroviruses. VP0 is not cleaved to form VP2 and VP4, so the 'VP2' β-barrel structure is complemented with a unique extended structure on the inside of the capsid. On the outer surface, a polyproline helix structure, not seen previously in picornaviruses is present at the C terminus of VP1, a position where integrin binding motifs are found in some other picornaviruses. A peptide corresponding to this polyproline motif somewhat attenuates virus infectivity, presumably blocking host-cell attachment. This may guide cellular receptor identification.

The impact of cortisol in steatotic and non-steatotic liver surgery.

PubMed

Cornide-Petronio, María Eugenia; Bujaldon, Esther; Mendes-Braz, Mariana; Avalos de León, Cindy G; Jiménez-Castro, Mónica B; Álvarez-Mercado, Ana I; Gracia-Sancho, Jordi; Rodés, Juan; Peralta, Carmen

2017-10-01

The intent of this study was to examine the effects of regulating cortisol levels on damage and regeneration in livers with and without steatosis subjected to partial hepatectomy under ischaemia-reperfusion. Ultimately, we found that lean animals undergoing liver resection displayed no changes in cortisol, whereas cortisol levels in plasma, liver and adipose tissue were elevated in obese animals undergoing such surgery. Such elevations were attributed to enzymatic upregulation, ensuring cortisol production, and downregulation of enzymes controlling cortisol clearance. In the absence of steatosis, exogenous cortisol administration boosted circulating cortisol, while inducing clearance of hepatic cortisol, thus maintaining low cortisol levels and preventing related hepatocellular harm. In the presence of steatosis, cortisol administration was marked by a substantial rise in intrahepatic availability, thereby exacerbating tissue damage and regenerative failure. The injurious effects of cortisol were linked to high hepatic acethylcholine levels. Upon administering an α7 nicotinic acethylcholine receptor antagonist, no changes in terms of tissue damage or regenerative lapse were apparent in steatotic livers. However, exposure to an M3 muscarinic acetylcholine receptor antagonist protected livers against damage, enhancing parenchymal regeneration and survival rate. These outcomes for the first time provide new mechanistic insight into surgically altered steatotic livers, underscoring the compelling therapeutic potential of cortisol-acetylcholine-M3 muscarinic receptors. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Comparative biology of rAAV transduction in ferret, pig and human airway epithelia.

PubMed

Liu, X; Luo, M; Guo, C; Yan, Z; Wang, Y; Engelhardt, J F

2007-11-01

Differences between rodent and human airway cell biology have made it difficult to translate recombinant adeno-associated virus (rAAV)-mediated gene therapies to the lung for cystic fibrosis (CF). As new ferret and pig models for CF become available, knowledge about host cell/vector interactions in these species will become increasingly important for testing potential gene therapies. To this end, we have compared the transduction biology of three rAAV serotypes (AAV1, 2 and 5) in human, ferret, pig and mouse-polarized airway epithelia. Our results indicate that apical transduction of ferret and pig airway epithelia with these rAAV serotypes closely mirrors that observed in human epithelia (rAAV1>rAAV2 congruent withrAAV5), while transduction of mouse epithelia was significantly different (rAAV1>rAAV5>rAAV2). Similarly, ferret, pig and human epithelia also shared serotype-specific differences in the polarity (apical vs basolateral) and proteasome dependence of rAAV transduction. Despite these parallels, N-linked sialic acid receptors were required for rAAV1 and rAAV5 transduction of human and mouse airway epithelia, but not ferret or pig airway epithelia. Hence, although the airway tropisms of rAAV serotypes 1, 2 and 5 are conserved better among ferret, pig and human as compared to mouse, viral receptors/co-receptors appear to maintain considerable species diversity.

Inefficient transmission of H5N1 influenza viruses in a ferret contact model.

PubMed

Yen, Hui-Ling; Lipatov, Aleksandr S; Ilyushina, Natalia A; Govorkova, Elena A; Franks, John; Yilmaz, Neziha; Douglas, Alan; Hay, Alan; Krauss, Scott; Rehg, Jerold E; Hoffmann, Erich; Webster, Robert G

2007-07-01

The abilities to infect and transmit efficiently among humans are essential for a novel influenza A virus to cause a pandemic. To evaluate the pandemic potential of widely disseminated H5N1 influenza viruses, a ferret contact model using experimental groups comprised of one inoculated ferret and two contact ferrets was used to study the transmissibility of four human H5N1 viruses isolated from 2003 to 2006. The effects of viral pathogenicity and receptor binding specificity (affinity to synthetic sialosaccharides with alpha2,3 or alpha2,6 linkages) on transmissibility were assessed. A/Vietnam/1203/04 and A/Vietnam/JP36-2/05 viruses, which possess "avian-like" alpha2,3-linked sialic acid (SA) receptor specificity, caused neurological symptoms and death in ferrets inoculated with 10(3) 50% tissue culture infectious doses. A/Hong Kong/213/03 and A/Turkey/65-596/06 viruses, which show binding affinity for "human-like" alpha2,6-linked SA receptors in addition to their affinity for alpha2,3-linked SA receptors, caused mild clinical symptoms and were not lethal to the ferrets. No transmission of A/Vietnam/1203/04 or A/Turkey/65-596/06 virus was detected. One contact ferret developed neutralizing antibodies to A/Hong Kong/213/03 but did not exhibit any clinical signs or detectable virus shedding. In two groups, one of two naïve contact ferrets had detectable virus after 6 to 8 days when housed together with the A/Vietnam/JP36-2/05 virus-inoculated ferrets. Infected contact ferrets showed severe clinical signs, although little or no virus was detected in nasal washes. This limited virus shedding explained the absence of secondary transmission from the infected contact ferret to the other naïve ferret that were housed together. Our results suggest that despite their receptor binding affinity, circulating H5N1 viruses retain molecular determinants that restrict their spread among mammalian species.

The natriuretic peptides BNP and CNP increase heart rate and electrical conduction by stimulating ionic currents in the sinoatrial node and atrial myocardium following activation of guanylyl cyclase-linked natriuretic peptide receptors.

PubMed

Springer, Jeremy; Azer, John; Hua, Rui; Robbins, Courtney; Adamczyk, Andrew; McBoyle, Sarah; Bissell, Mary Beth; Rose, Robert A

2012-05-01

Natriuretic peptides (NPs) are best known for their ability to regulate blood vessel tone and kidney function whereas their electrophysiological effects on the heart are less clear. Here, we measured the effects of BNP and CNP on sinoatrial node (SAN) and atrial electrophysiology in isolated hearts as well as isolated SAN and right atrial myocytes from mice. BNP and CNP dose-dependently increased heart rate and conduction through the heart as indicated by reductions in R-R interval, P wave duration and P-R interval on ECGs. In conjunction with these ECG changes BNP and CNP (100 nM) increased spontaneous action potential frequency in isolated SAN myocytes by increasing L-type Ca(2+) current (I(Ca,L)) and the hyperpolarization-activated current (I(f)). BNP had no effect on right atrial myocyte APs in basal conditions; however, in the presence of isoproterenol (10nM), BNP increased atrial AP duration and I(Ca,L). Quantitative gene expression and immunocytochemistry data show that all three NP receptors (NPR-A, NPR-B and NPR-C) are expressed in the SAN and atrium. The effects of BNP and CNP on SAN and right atrial myocytes were maintained in mutant mice lacking functional NPR-C receptors and blocked by the NPR-A antagonist A71915 indicating that BNP and CNP function through their guanylyl cyclase-linked receptors. Our data also show that the effects of BNP and CNP are completely absent in the presence of the phosphodiesterase 3 inhibitor milrinone. Based on these data we conclude that NPs can increase heart rate and electrical conduction by activating the guanylyl cyclase-linked NPR-A and NPR-B receptors and inhibiting PDE3 activity. Copyright © 2012 Elsevier Ltd. All rights reserved.

Starring role of toll-like receptor-4 activation in the gut-liver axis

PubMed Central

Carotti, Simone; Guarino, Michele Pier Luca; Vespasiani-Gentilucci, Umberto; Morini, Sergio

2015-01-01

Since the introduction of the term “gut-liver axis”, many studies have focused on the functional links of intestinal microbiota, barrier function and immune responses to liver physiology. Intestinal and extra-intestinal diseases alter microbiota composition and lead to dysbiosis, which aggravates impaired intestinal barrier function via increased lipopolysaccharide translocation. The subsequent increased passage of gut-derived product from the intestinal lumen to the organ wall and bloodstream affects gut motility and liver biology. The activation of the toll-like receptor 4 (TLR-4) likely plays a key role in both cases. This review analyzed the most recent literature on the gut-liver axis, with a particular focus on the role of TLR-4 activation. Findings that linked liver disease with dysbiosis are evaluated, and links between dysbiosis and alterations of intestinal permeability and motility are discussed. We also examine the mechanisms of translocated gut bacteria and/or the bacterial product activation of liver inflammation and fibrogenesis via activity on different hepatic cell types. PMID:26600967

LRP8-Reelin-regulated Neuronal (LRN) Enhancer Signature Underlying Learning and Memory Formation

PubMed Central

Telese, Francesca; Ma, Qi; Perez, Patricia Montilla; Notani, Dimple; Oh, Soohwan; Li, Wenbo; Comoletti, Davide; Ohgi, Kenneth A.; Taylor, Havilah; Rosenfeld, Michael G.

2015-01-01

Summary One of the exceptional properties of the brain is its ability to acquire new knowledge through learning and to store that information through memory. The epigenetic mechanisms linking changes in neuronal transcriptional programs to behavioral plasticity remain largely unknown. Here, we identify the epigenetic signature of the neuronal enhancers required for transcriptional regulation of synaptic plasticity genes during memory formation, linking this to Reelin signaling. The binding of Reelin to its receptor, LRP8, triggers activation of this cohort of LRP8-Reelin-regulated-Neuronal (LRN) enhancers that serve as the ultimate convergence point of a novel synapse-to-nucleus pathway. Reelin simultaneously regulates NMDA-receptor transmission, which reciprocally permits the required, γ-secretase-dependent cleavage of LRP8, revealing an unprecedented role for its intracellular domain in the regulation of synaptically generated signals. These results uncover an in vivo enhancer code serving as a critical molecular component of cognition and relevant to psychiatric disorders linked to defects in Reelin signaling. PMID:25892301

The interrelationship of dopamine D2-like receptor availability in striatal and extrastriatal brain regions in healthy humans: A principal component analysis of [18F]Fallypride binding

PubMed Central

Zald, David H.; Woodward, Neil D.; Cowan, Ronald L.; Riccardi, Patrizia; Ansari, M. Sib; Baldwin, Ronald M.; Cowan, Ronald L.; Smith, Clarence E.; Hakyemez, Helene; Li, Rui; Kessler, Robert M.

2010-01-01

Individual differences in dopamine D2-like receptor availability arise across all brain regions expressing D2-like receptors. However, the inter-relationships in receptor availability across brain regions are poorly understood. To address this issue, we examined the relationship between D2-like binding potential (BPND) across striatal and extrastriatal regions in a sample of healthy participants. PET imaging was performed with the high affinity D2/D3 ligand [18F]fallypride in 45 participants. BPND images were submitted to voxel-wise principal components analysis to determine the pattern of associations across brain regions. Individual differences in D2-like BPND were explained by three distinguishable components. A single component explained almost all of the variance within the striatum, indicating that individual differences in receptor availability vary in a homogenous manner across the caudate, putamen, and ventral striatum. Cortical BPND was only modestly related to striatal BPND, and mostly loaded on a distinct component. After controlling for the general level of cortical D2-like BPND, an inverse relationship emerged between receptor availability in the striatum and the ventral temporal and ventromedial frontal cortices, suggesting possible cross-regulation of D2-like receptors in these regions. The analysis additionally revealed evidence of: 1) a distinct component involving the midbrain and limbic areas; 2) a dissociation between BPND in the medial and lateral temporal regions; and 3) a dissociation between BPND in the medial/midline and lateral thalamus. In summary, individual differences in D2-like receptor availability reflect several distinct patterns. This conclusion has significant implications for neuropsychiatric models that posit global or regionally specific relationships between dopaminergic tone and behavior. PMID:20149883

Sigma-1 receptor chaperone and brain-derived neurotrophic factor: emerging links between cardiovascular disease and depression.

PubMed

Hashimoto, Kenji

2013-01-01

Epidemiological studies have demonstrated a close relationship between depression and cardiovascular disease (CVD). Although it is known that the central nervous system (CNS) contributes to this relationship, the detailed mechanisms involved in this process remain unclear. Recent studies suggest that the endoplasmic reticulum (ER) molecular chaperone sigma-1 receptor and brain-derived neurotrophic factor (BDNF) play a role in the pathophysiology of CVD and depression. Several meta-analysis studies have showed that levels of BDNF in the blood of patients with major depressive disorder (MDD) are lower than normal controls, indicating that blood BDNF might be a biomarker for depression. Furthermore, blood levels of BDNF in patients with CVD are also lower than normal controls. A recent study using conditional BDNF knock-out mice in animal models of myocardial infarction highlighted the role of CNS-mediated mechanisms in the cardioprotective effects of BDNF. In addition, a recent study shows that decreased levels of sigma-1 receptor in the mouse brain contribute to the association between heart failure and depression. Moreover, sigma-1 receptor agonists, including the endogenous neurosteroid dehydroepiandosterone (DHEA) and the selective serotonin reuptake inhibitor (SSRI) fluvoxamine, show potent cardioprotective and antidepressive effects in rodents, via sigma-1 receptor stimulation. Interestingly, agonist activation of sigma-1 receptors increased the secretion of mature BDNF from its precursor proBDNF via chaperone activity in the ER. Given the role of ER stress in the pathophysiology of CVD and MDD, the author will discuss the potential link between sigma-1 receptors and BDNF-TrkB pathway in the pathophysiology of these two diseases. Finally, the author will make a case for potent sigma-1 receptor agonists and TrkB agonists as new potential therapeutic drugs for depressive patients with CVD. Copyright © 2012 Elsevier Ltd. All rights reserved.

Bisphenol A affects androgen receptor function via multiple mechanisms.

PubMed

Teng, Christina; Goodwin, Bonnie; Shockley, Keith; Xia, Menghang; Huang, Ruili; Norris, John; Merrick, B Alex; Jetten, Anton M; Austin, Christopher P; Tice, Raymond R

2013-05-25

Bisphenol A (BPA), is a well-known endocrine disruptor compound (EDC) that affects the normal development and function of the female and male reproductive system, however the mechanisms of action remain unclear. To investigate the molecular mechanisms of how BPA may affect ten different nuclear receptors, stable cell lines containing individual nuclear receptor ligand binding domain (LBD)-linked to the β-Gal reporter were examined by a quantitative high throughput screening (qHTS) format in the Tox21 Screening Program of the NIH. The results showed that two receptors, estrogen receptor alpha (ERα) and androgen receptor (AR), are affected by BPA in opposite direction. To confirm the observed effects of BPA on ERα and AR, we performed transient transfection experiments with full-length receptors and their corresponding response elements linked to luciferase reporters. We also included in this study two BPA analogs, bisphenol AF (BPAF) and bisphenol S (BPS). As seen in African green monkey kidney CV1 cells, the present study confirmed that BPA and BPAF act as ERα agonists (half maximal effective concentration EC50 of 10-100 nM) and as AR antagonists (half maximal inhibitory concentration IC50 of 1-2 μM). Both BPA and BPAF antagonized AR function via competitive inhibition of the action of synthetic androgen R1881. BPS with lower estrogenic activity (EC50 of 2.2 μM), did not compete with R1881 for AR binding, when tested at 30 μM. Finally, the effects of BPA were also evaluated in a nuclear translocation assays using EGPF-tagged receptors. Similar to 17β-estradiol (E2) which was used as control, BPA was able to enhance ERα nuclear foci formation but at a 100-fold higher concentration. Although BPA was able to bind AR, the nuclear translocation was reduced. Furthermore, BPA was unable to induce functional foci in the nuclei and is consistent with the transient transfection study that BPA is unable to activate AR. Published by Elsevier Ireland Ltd.

Characterization of the N-linked high-mannose oligosaccharides of the insulin pro-receptor and mature insulin receptor subunits.

PubMed

McElduff, A; Watkinson, A; Hedo, J A; Gorden, P

1986-11-01

The insulin receptor is synthesized as a 190,000-Mr single-chain precursor that contains exclusively asparagine-N-linked high-mannose-type carbohydrate chains. In this study we have characterized the structure of the pro-receptor oligosaccharides. IM-9 lymphocytes were pulse-chase-labelled with [3H]mannose, and the insulin pro-receptor was isolated by immunoprecipitation and SDS/polyacrylamide-gel electrophoresis. The pro-receptor oligosaccharides were removed from the protein backbone with endoglycosidase H and analysed by h.p.l.c. Immediately after a [3H]mannose pulse the largest oligosaccharide found in the pro-receptor was Glc1Man9GlcNAc2; this structure represented only a small fraction (3%) of the total. The predominant oligosaccharides present in the pro-receptor were Man9GlcNAc2 (25%) and Man8GlcNAc2 (48%). Smaller oligosaccharides were also detected: Man7GlcNAc2 (18%), Man6GlcNAc2 (3%) and Man5GlcNAc2 (3%). The relative distribution of the different oligosaccharides did not change at 1, 2 or 3 h after the pulse with the exception of the rapid disappearance of the Glc1Man9GlcNAc2 component. The mature alpha- and beta-subunits of the insulin receptor are known to contain both high-mannose-type and complex-type oligosaccharides. We have also examined here the structure of the high-mannose chains of these subunits. The predominant species in the alpha-subunit was Man8GlcNAc2 whereas in the beta-subunit it was Man7GlcNAc2. These results demonstrate that most (approx. 75%) oligosaccharides of the insulin pro-receptor are chains of the type Man8GlcNAc2 or Man9GlcNAc2. Thus, assuming that a Glc3Man9GlcNAc2 species is transferred co-translationally, carbohydrate processing of the pro-receptor appears to be very rapid and limited to the removal of the three glucose residues and one mannose residue. Further mannose removal does not occur until the pro-receptor has been proteolytically cleaved. In addition, the degree of mannose trimming appears to be different in the alpha- and beta-subunits.

Characterization of the N-linked high-mannose oligosaccharides of the insulin pro-receptor and mature insulin receptor subunits.

PubMed Central

McElduff, A; Watkinson, A; Hedo, J A; Gorden, P

1986-01-01

The insulin receptor is synthesized as a 190,000-Mr single-chain precursor that contains exclusively asparagine-N-linked high-mannose-type carbohydrate chains. In this study we have characterized the structure of the pro-receptor oligosaccharides. IM-9 lymphocytes were pulse-chase-labelled with [3H]mannose, and the insulin pro-receptor was isolated by immunoprecipitation and SDS/polyacrylamide-gel electrophoresis. The pro-receptor oligosaccharides were removed from the protein backbone with endoglycosidase H and analysed by h.p.l.c. Immediately after a [3H]mannose pulse the largest oligosaccharide found in the pro-receptor was Glc1Man9GlcNAc2; this structure represented only a small fraction (3%) of the total. The predominant oligosaccharides present in the pro-receptor were Man9GlcNAc2 (25%) and Man8GlcNAc2 (48%). Smaller oligosaccharides were also detected: Man7GlcNAc2 (18%), Man6GlcNAc2 (3%) and Man5GlcNAc2 (3%). The relative distribution of the different oligosaccharides did not change at 1, 2 or 3 h after the pulse with the exception of the rapid disappearance of the Glc1Man9GlcNAc2 component. The mature alpha- and beta-subunits of the insulin receptor are known to contain both high-mannose-type and complex-type oligosaccharides. We have also examined here the structure of the high-mannose chains of these subunits. The predominant species in the alpha-subunit was Man8GlcNAc2 whereas in the beta-subunit it was Man7GlcNAc2. These results demonstrate that most (approx. 75%) oligosaccharides of the insulin pro-receptor are chains of the type Man8GlcNAc2 or Man9GlcNAc2. Thus, assuming that a Glc3Man9GlcNAc2 species is transferred co-translationally, carbohydrate processing of the pro-receptor appears to be very rapid and limited to the removal of the three glucose residues and one mannose residue. Further mannose removal does not occur until the pro-receptor has been proteolytically cleaved. In addition, the degree of mannose trimming appears to be different in the alpha- and beta-subunits. Images Fig. 1. PMID:3827820

Functional Genetic Variation in Dopamine Signaling Moderates Prefrontal Cortical Activity During Risky Decision Making.

PubMed

Kohno, Milky; Nurmi, Erika L; Laughlin, Christopher P; Morales, Angelica M; Gail, Emma H; Hellemann, Gerhard S; London, Edythe D

2016-02-01

Brain imaging has revealed links between prefrontal activity during risky decision-making and striatal dopamine receptors. Specifically, striatal dopamine D2-like receptor availability is correlated with risk-taking behavior and sensitivity of prefrontal activation to risk in the Balloon Analogue Risk Task (BART). The extent to which these associations, involving a single neurochemical measure, reflect more general effects of dopaminergic functioning on risky decision making, however, is unknown. Here, 65 healthy participants provided genotypes and performed the BART during functional magnetic resonance imaging. For each participant, dopamine function was assessed using a gene composite score combining known functional variation across five genes involved in dopaminergic signaling: DRD2, DRD3, DRD4, DAT1, and COMT. The gene composite score was negatively related to dorsolateral prefrontal cortical function during risky decision making, and nonlinearly related to earnings on the task. Iterative permutations of all possible allelic variations (7777 allelic combinations) was tested on brain function in an independently defined region of the prefrontal cortex and confirmed empirical validity of the composite score, which yielded stronger association than 95% of all other possible combinations. The gene composite score also accounted for a greater proportion of variability in neural and behavioral measures than the independent effects of each gene variant, indicating that the combined effects of functional dopamine pathway genes can provide a robust assessment, presumably reflecting the cumulative and potentially interactive effects on brain function. Our findings support the view that the links between dopaminergic signaling, prefrontal function, and decision making vary as a function of dopamine signaling capacity.

Selectivity in the Use of Gi/o Proteins Is Determined by the DRF Motif in CXCR6 and Is Cell-Type Specific.

PubMed

Singh, Satya P; Foley, John F; Zhang, Hongwei H; Hurt, Darrell E; Richards, Jennifer L; Smith, Craig S; Liao, Fang; Farber, Joshua M

2015-11-01

CXCR6, the receptor for CXCL16, is expressed on multiple cell types and can be a coreceptor for human immunodeficiency virus 1. Except for CXCR6, all human chemokine receptors contain the D(3.49)R(3.50)Y(3.51) sequence, and all but two contain A(3.53) at the cytoplasmic terminus of the third transmembrane helix (H3C), a region within class A G protein-coupled receptors that contacts G proteins. In CXCR6, H3C contains D(3.49)R(3.50)F(3.51)I(3.52)V(3.53) at positions 126-130. We investigated the importance and interdependence of the canonical D126 and the noncanonical F128 and V130 in CXCR6 by mutating D126 to Y, F128 to Y, and V130 to A singly and in combination. For comparison, we mutated the analogous positions D142, Y144, and A146 to Y, F, and V, respectively, in CCR6, a related receptor containing the canonical sequences. Mutants were analyzed in both human embryonic kidney 293T and Jurkat E6-1 cells. Our data show that for CXCR6 and/or CCR6, mutations in H3C can affect both receptor signaling and chemokine binding; noncanonical H3C sequences are functionally linked, with dual changes mitigating the effects of single mutations; mutations in H3C that compromise receptor activity show selective defects in the use of individual Gi/o proteins; and the effects of mutations in H3C on receptor function and selectivity in Gi/o protein use can be cell-type specific. Our findings indicate that the ability of CXCR6 to make promiscuous use of the available Gi/o proteins is exquisitely dependent on sequences within the H3C and suggest that the native sequence allows for preservation of this function across different cellular environments. U.S. Government work not protected by U.S. copyright.

Selectivity in the Use of Gi/o Proteins Is Determined by the DRF Motif in CXCR6 and Is Cell-Type Specific

PubMed Central

Singh, Satya P.; Foley, John F.; Zhang, Hongwei H.; Hurt, Darrell E.; Richards, Jennifer L.; Smith, Craig S.; Liao, Fang

2015-01-01

CXCR6, the receptor for CXCL16, is expressed on multiple cell types and can be a coreceptor for human immunodeficiency virus 1. Except for CXCR6, all human chemokine receptors contain the D3.49R3.50Y3.51 sequence, and all but two contain A3.53 at the cytoplasmic terminus of the third transmembrane helix (H3C), a region within class A G protein–coupled receptors that contacts G proteins. In CXCR6, H3C contains D3.49R3.50F3.51I3.52V3.53 at positions 126–130. We investigated the importance and interdependence of the canonical D126 and the noncanonical F128 and V130 in CXCR6 by mutating D126 to Y, F128 to Y, and V130 to A singly and in combination. For comparison, we mutated the analogous positions D142, Y144, and A146 to Y, F, and V, respectively, in CCR6, a related receptor containing the canonical sequences. Mutants were analyzed in both human embryonic kidney 293T and Jurkat E6-1 cells. Our data show that for CXCR6 and/or CCR6, mutations in H3C can affect both receptor signaling and chemokine binding; noncanonical H3C sequences are functionally linked, with dual changes mitigating the effects of single mutations; mutations in H3C that compromise receptor activity show selective defects in the use of individual Gi/o proteins; and the effects of mutations in H3C on receptor function and selectivity in Gi/o protein use can be cell-type specific. Our findings indicate that the ability of CXCR6 to make promiscuous use of the available Gi/o proteins is exquisitely dependent on sequences within the H3C and suggest that the native sequence allows for preservation of this function across different cellular environments. PMID:26316539

Negative regulation of parathyroid hormone-related protein expression by steroid hormones

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

Kajitani, Takashi; Tamamori-Adachi, Mimi; Okinaga, Hiroko

Highlights: {yields} Steroid hormones repress expression of PTHrP in the cell lines where the corresponding nuclear receptors are expressed. {yields} Nuclear receptors are required for suppression of PTHrP expression by steroid hormones, except for androgen receptor. {yields} Androgen-induced suppression of PTHrP expression appears to be mediated by estrogen receptor. -- Abstract: Elevated parathyroid hormone-related protein (PTHrP) is responsible for humoral hypercalcemia of malignancy (HHM), which is of clinical significance in treatment of terminal patients with malignancies. Steroid hormones were known to cause suppression of PTHrP expression. However, detailed studies linking multiple steroid hormones to PTHrP expression are lacking. Here wemore » studied PTHrP expression in response to steroid hormones in four cell lines with excessive PTHrP production. Our study established that steroid hormones negatively regulate PTHrP expression. Vitamin D receptor, estrogen receptor {alpha}, glucocorticoid receptor, and progesterone receptor, were required for repression of PTHrP expression by the cognate ligands. A notable exception was the androgen receptor, which was dispensable for suppression of PTHrP expression in androgen-treated cells. We propose a pathway(s) involving nuclear receptors to suppress PTHrP expression.« less

GABA(C) receptors: a molecular view.

PubMed

Enz, R

2001-08-01

In the central nervous system inhibitory neurotransmission is primarily achieved through activation of receptors for gamma-aminobutyric acid (GABA). Three types of GABA receptors have been identified on the basis of their pharmacological and electrophysiological properties. The predominant type, termed GABA(A), and a recently identified GABA(C) type, form ligand-gated chloride channels, whereas GABA(B) receptors activate separate cation channels via G proteins. Based on their homology to nicotinic acetylcholine receptors, GABA(C) receptors are believed to be oligomeric protein complexes composed of five subunits in a pentameric arrangement. To date up to five different GABA(C) receptors subunits have been identified in various species. Recent studies have shed new light on the biological characteristics of GABA(C) receptors, including the chromosomal localization of its subunit genes and resulting links to deseases, the cloning of new splice variants, the identification of GABA(C) receptor-associated proteins, the identification of domains involved in subunit assembly, and finally structure/function studies examining functional consequences of introduced mutations. This review summarizes recent data in view of the molecular structure of GABA(C) receptors and presents new insights into the biological function of this protein in the retina.

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

Taguchi, Takahiro; Testa, J.R.; Mitcham, J.L.

This report describes the localization of the the TIL gene to human chromosome 4p14 using fluorescence in situ hybridization. This gene encodes a protein which is related to the Drosophila transmembrane receptor Toll and the mammalian interleukin-1 receptor, which share similarities in structure and function. The Drosophila gene is also important during embryonic development, which makes TIL a candidate locus for human congenital malformations that are genetically linked to human chromosome 4. 17 refs., 1 fig.

Linked magnolol dimer as a selective PPARγ agonist - Structure-based rational design, synthesis, and bioactivity evaluation.

PubMed

Dreier, Dominik; Latkolik, Simone; Rycek, Lukas; Schnürch, Michael; Dymáková, Andrea; Atanasov, Atanas G; Ladurner, Angela; Heiss, Elke H; Stuppner, Hermann; Schuster, Daniela; Mihovilovic, Marko D; Dirsch, Verena M

2017-10-20

The nuclear receptors peroxisome proliferator-activated receptor γ (PPARγ) and its hetero-dimerization partner retinoid X receptor α (RXRα) are considered as drug targets in the treatment of diseases like the metabolic syndrome and diabetes mellitus type 2. Effort has been made to develop new agonists for PPARγ to obtain ligands with more favorable properties than currently used drugs. Magnolol was previously described as dual agonist of PPARγ and RXRα. Here we show the structure-based rational design of a linked magnolol dimer within the ligand binding domain of PPARγ and its synthesis. Furthermore, we evaluated its binding properties and functionality as a PPARγ agonist in vitro with the purified PPARγ ligand binding domain (LBD) and in a cell-based nuclear receptor transactivation model in HEK293 cells. We determined the synthesized magnolol dimer to bind with much higher affinity to the purified PPARγ ligand binding domain than magnolol (K i values of 5.03 and 64.42 nM, respectively). Regarding their potency to transactivate a PPARγ-dependent luciferase gene both compounds were equally effective. This is likely due to the PPARγ specificity of the newly designed magnolol dimer and lack of RXRα-driven transactivation activity by this dimeric compound.

Transmembrane Domains of Attraction on the TSH Receptor

PubMed Central

Ali, M. Rejwan; Mezei, Mihaly; Davies, Terry F.

2015-01-01

The TSH receptor (TSHR) has the propensity to form dimers and oligomers. Our data using ectodomain-truncated TSHRs indicated that the predominant interfaces for oligomerization reside in the transmembrane (TM) domain. To map the potentially interacting residues, we first performed in silico studies of the TSHR transmembrane domain using a homology model and using Brownian dynamics (BD). The cluster of dimer conformations obtained from BD analysis indicated that TM1 made contact with TM4 and two residues in TM2 made contact with TM5. To confirm the proximity of these contact residues, we then generated cysteine mutants at all six contact residues predicted by the BD analysis and performed cysteine cross-linking studies. These results showed that the predicted helices in the protomer were indeed involved in proximity interactions. Furthermore, an alternative experimental approach, receptor truncation experiments and LH receptor sequence substitution experiments, identified TM1 harboring a major region involved in TSHR oligomerization, in agreement with the conclusion from the cross-linking studies. Point mutations of the predicted interacting residues did not yield a substantial decrease in oligomerization, unlike the truncation of the TM1, so we concluded that constitutive oligomerization must involve interfaces forming domains of attraction in a cooperative manner that is not dominated by interactions between specific residues. PMID:25406938

Essential role of integrin-linked kinase in regulation of phagocytosis in keratinocytes.

PubMed

Sayedyahossein, Samar; Nini, Lylia; Irvine, Timothy S; Dagnino, Lina

2012-10-01

Phagocytic melanosome uptake by epidermal keratinocytes is a central protective mechanism against damage induced by ultraviolet radiation. Phagocytosis requires formation of pseudopodia via actin cytoskeleton rearrangements. Integrin-linked kinase (ILK) is an important modulator of actin cytoskeletal dynamics. We have examined the role of ILK in regulation of phagocytosis, using epidermal keratinocytes isolated from mice with epidermis-restricted Ilk gene inactivation. ILK-deficient cells exhibited severely impaired capacity to engulf fluorescent microspheres in response to stimulation of the keratinocyte growth factor (KGF) receptor or the protease-activated receptor-2. KGF induced ERK phosphorylation in ILK-expressing and ILK-deficient cells, suggesting that ILK is not essential for KGF receptor signaling. In contrast, KGF promoted activation of Rac1 and formation of pseudopodia in ILK-expressing, but not in ILK-deficient cells. Rac1-deficient keratinocytes also showed substantially impaired phagocytic ability, underlining the importance of ILK-dependent Rac1 function for particle engulfment. Finally, cross-modulation of KGF receptors by integrins may be another important element, as integrin β1-deficient keratinocytes also fail to show significant phagocytosis in response to KGF. Thus, we have identified a novel signaling pathway essential for phagocytosis in keratinocytes, which involves ILK-dependent activation of Rac1 in response to KGF, resulting in the formation of pseudopodia and particle uptake.

Role of osteoprotegerin/receptor activator of nuclear factor kappa B/receptor activator of nuclear factor kappa B ligand axis in nonalcoholic fatty liver disease.

PubMed

Pacifico, Lucia; Andreoli, Gian Marco; D'Avanzo, Miriam; De Mitri, Delia; Pierimarchi, Pasquale

2018-05-21

Concomitantly with the increase in the prevalences of overweight/obesity, nonalcoholic fatty liver disease (NAFLD) has worldwide become the main cause of chronic liver disease in both adults and children. Patients with fatty liver display features of metabolic syndrome (MetS), like insulin resistance (IR), glucose intolerance, hypertension and dyslipidemia. Recently, epidemiological studies have linked obesity, MetS, and NAFLD to decreased bone mineral density and osteoporosis, highlighting an intricate interplay among bone, adipose tissue, and liver. Osteoprotegerin (OPG), an important symbol of the receptor activator of nuclear factor-B ligand/receptor activator of nuclear factor kappa B/OPG system activation, typically considered for its role in bone metabolism, may also play critical roles in the initiation and perpetuation of obesity-related comorbidities. Clinical data have indicated that OPG concentrations are associated with hypertension, left ventricular hypertrophy, vascular calcification, endothelial dysfunction, and severity of liver damage in chronic hepatitis C. Nonetheless, the relationship between circulating OPG and IR as a key feature of MetS as well as between OPG and NAFLD remains uncertain. Thus, the aims of the present review are to provide the existent knowledge on these associations and to discuss briefly the underlying mechanisms linking OPG and NAFLD.

Peroxisome proliferator-activated receptor agonists modulate neuropathic pain: a link to chemokines?

PubMed Central

Freitag, Caroline M.; Miller, Richard J.

2014-01-01

Chronic pain presents a widespread and intractable medical problem. While numerous pharmaceuticals are used to treat chronic pain, drugs that are safe for extended use and highly effective at treating the most severe pain do not yet exist. Chronic pain resulting from nervous system injury (neuropathic pain) is common in conditions ranging from multiple sclerosis to HIV-1 infection to type II diabetes. Inflammation caused by neuropathy is believed to contribute to the generation and maintenance of neuropathic pain. Chemokines are key inflammatory mediators, several of which (MCP-1, RANTES, MIP-1α, fractalkine, SDF-1 among others) have been linked to chronic, neuropathic pain in both human conditions and animal models. The important roles chemokines play in inflammation and pain make them an attractive therapeutic target. Peroxisome proliferator-activated receptors (PPARs) are a family of nuclear receptors known for their roles in metabolism. Recent research has revealed that PPARs also play a role in inflammatory gene repression. PPAR agonists have wide-ranging effects including inhibition of chemokine expression and pain behavior reduction in animal models. Experimental evidence suggests a connection between the pain ameliorating effects of PPAR agonists and suppression of inflammatory gene expression, including chemokines. In early clinical research, one PPARα agonist, palmitoylethanolamide (PEA), shows promise in relieving chronic pain. If this link can be better established, PPAR agonists may represent a new drug therapy for neuropathic pain. PMID:25191225

Chitin receptor CERK1 links salt stress and chitin-triggered innate immunity in Arabidopsis.

PubMed

Espinoza, Catherine; Liang, Yan; Stacey, Gary

2017-03-01

In nature, plants need to respond to multiple environmental stresses that require the involvement and fine-tuning of different stress signaling pathways. Cross-tolerance, in which plants pre-treated with chitin (a fungal microbe-associated molecular pattern) have improved salt tolerance, was observed in Arabidopsis, but is not well understood. Here, we show a unique link between chitin and salt signaling mediated by the chitin receptor CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1). Transcriptome analysis revealed that salt stress-induced genes are highly correlated with chitin-induced genes, although this was not observed with other microbe-associated molecular patterns (MAMPs) or with other abiotic stresses. The cerk1 mutant was more susceptible to NaCl than was the wild type. cerk1 plants had an irregular increase of cytosolic calcium ([Ca 2+ ] cyt ) after NaCl treatment. Bimolecular fluorescence complementation (BiFC) and co-immunoprecipitation experiments indicated that CERK1 physically interacts with ANNEXIN 1 (ANN1), which was reported to form a calcium-permeable channel that contributes to the NaCl-induced [Ca 2+ ] cyt signal. In turn, ann1 mutants showed elevated chitin-induced rapid responses. In short, molecular components previously shown to function in chitin or salt signaling physically interact and intimately link the downstream responses to fungal attack and salt stress. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

Subcellular localization of estradiol receptor in MCF7 cells studied with nanogold-labelled antibody fragments.

PubMed

Kessels, M M; Qualmann, B; Thole, H H; Sierralta, W D

1998-01-01

Ultrastructural localization studies of estradiol receptor in hormone-deprived and hormone-stimulated MCF7 cells were done using F(ab') fragments of three different antibodies (#402, 13H2, HT277) covalently linked to nanogold. These ultra-small, non-charged immunoreagents, combined with a size-enlargement by silver enhancement, localized estradiol receptor in both nuclear and cytoplasmic areas of non-stimulated target cells; stimulation with the steroid induced a predominantly nuclear labelling. In the cytoplasm of resting cells, tagging was often observed at or in the proximity of stress fibers. In the nucleus a large proportion of receptor was found inside the nucleolus, specially with the reagent derived from antibody 13H2. We postulate that different accessibilities of receptor epitopes account for the different labelling densities observed at cytoskeletal elements and the nucleoli.

Dietary Lignan Intake and Androgen Receptor Expression in Breast Tumors

PubMed Central

Williams, AnnaLynn M.; Bonner, Matthew; Ochs-Balcom, Heather M.; Hwang, Helena; Morrison, Carl; McCann, Susan E.

2014-01-01

Purpose Lignans, a class of phytoestrogen commonly found in the Western diet, have been linked to decreased breast cancer risks in epidemiologic studies. Similar to estrogen receptors, the androgen receptor (AR), a prognostic factor in breast tumors, may be affected by lignans. However, few studies have investigated this link in the context of breast cancer etiology. We evaluated the relationship between dietary lignan intake and androgen receptor expression in incident breast tumors. Methods Tumor tissue, epidemiological, and clinical data were collected from 216 women with incident, primary, histologically-confirmed breast cancer enrolled in the Roswell Park Cancer Institute (RPCI) Data Bank and BioRepository (DBBR). On average, three tumor cores from each participant were assembled into a Tissue MicroArray (TMA). After immunohistochemical staining, a trained RPCI pathologist determined AR status of each core. Lignan intake was calculated from a food frequency questionnaire collected upon enrollment into the DBBR. Results We observed a weak positive association between dietary lignans and AR expression (β (SE) 27.6 (17.0), p 0.10) and there was no significant difference in lignan intake across categories of AR expression (p=0.09, R2 =0.35). Conclusion Our results do not support a clear relationship between dietary lignan intake and AR expression. This investigation is the first, to our knowledge, to examine dietary lignan intake and AR expression in breast tumors. Further research is needed within a larger, more representative sample to determine if lignan intake is truly associated with androgen receptor expression. PMID:25471060

Adiponectin and Its Receptors in the Ovary: Further Evidence for a Link between Obesity and Hyperandrogenism in Polycystic Ovary Syndrome

PubMed Central

Comim, Fabio V.; Hardy, Kate; Franks, Stephen

2013-01-01

Polycystic ovary syndrome (PCOS), characterized by ovarian androgen excess, is the commonest endocrine disorder in women. Obesity increases androgen synthesis, a phenomenon attributed to the accompanying hyperinsulinemia. Our hypothesis was that adipokines, fat cell-derived hormones, play a direct role in modulating ovarian androgen secretion. Therefore, the aims of this study were to explore the effects of adipokines (in particular, adiponectin) on ovarian steroidogenesis and compare the expression of adiponectin receptors in ovaries from women with and without PCO. Sections of archived human ovaries (nine from women with normal ovaries and 16 with PCOS, classified histologically, with reference to menstrual history and ultrasound) were analysed by quantitative morphometry and the proportion of positive-labelling cells compared. In addition, studies of androgen production in relation to adipokine function in primary bovine theca cell culture were also performed. A significantly lower proportion of theca cells expressed adiponectin receptors 1 and 2 (AdipoR1, AdipoR2) in polycystic ovaries than in normal ovaries. In cultured theca cells, adiponectin suppressed androstenedione production and gene expression of LH receptor and key enzymes in the androgen synthesis pathway. Moreover, knockdown of genes for AdipoR1 and AdipoR2 was associated with increased androstenedione secretion by bovine theca cells. These results provide evidence for a direct link between fat cell metabolism and ovarian steroidogenesis, suggesting that disruption of adiponectin and/or its receptors plays a key role in pathogenesis of hyperandrogenism in PCOS. PMID:24260388

A cannabinoid link between mitochondria and memory.

PubMed

Hebert-Chatelain, Etienne; Desprez, Tifany; Serrat, Román; Bellocchio, Luigi; Soria-Gomez, Edgar; Busquets-Garcia, Arnau; Pagano Zottola, Antonio Christian; Delamarre, Anna; Cannich, Astrid; Vincent, Peggy; Varilh, Marjorie; Robin, Laurie M; Terral, Geoffrey; García-Fernández, M Dolores; Colavita, Michelangelo; Mazier, Wilfrid; Drago, Filippo; Puente, Nagore; Reguero, Leire; Elezgarai, Izaskun; Dupuy, Jean-William; Cota, Daniela; Lopez-Rodriguez, Maria-Luz; Barreda-Gómez, Gabriel; Massa, Federico; Grandes, Pedro; Bénard, Giovanni; Marsicano, Giovanni

2016-11-24

Cellular activity in the brain depends on the high energetic support provided by mitochondria, the cell organelles which use energy sources to generate ATP. Acute cannabinoid intoxication induces amnesia in humans and animals, and the activation of type-1 cannabinoid receptors present at brain mitochondria membranes (mtCB 1 ) can directly alter mitochondrial energetic activity. Although the pathological impact of chronic mitochondrial dysfunctions in the brain is well established, the involvement of acute modulation of mitochondrial activity in high brain functions, including learning and memory, is unknown. Here, we show that acute cannabinoid-induced memory impairment in mice requires activation of hippocampal mtCB 1 receptors. Genetic exclusion of CB 1 receptors from hippocampal mitochondria prevents cannabinoid-induced reduction of mitochondrial mobility, synaptic transmission and memory formation. mtCB 1 receptors signal through intra-mitochondrial Gα i protein activation and consequent inhibition of soluble-adenylyl cyclase (sAC). The resulting inhibition of protein kinase A (PKA)-dependent phosphorylation of specific subunits of the mitochondrial electron transport system eventually leads to decreased cellular respiration. Hippocampal inhibition of sAC activity or manipulation of intra-mitochondrial PKA signalling or phosphorylation of the Complex I subunit NDUFS2 inhibit bioenergetic and amnesic effects of cannabinoids. Thus, the G protein-coupled mtCB 1 receptors regulate memory processes via modulation of mitochondrial energy metabolism. By directly linking mitochondrial activity to memory formation, these data reveal that bioenergetic processes are primary acute regulators of cognitive functions.

High affinity binding of 125I-neurotensin to dispersed cells from chicken liver and brain.

PubMed

Mitra, S P; Carraway, R E

1997-01-01

Dispersed cells from chicken brain and liver were found to possess cell surface binding sites for 125I-neurotensin (125I-NT). Scatchard analyses indicated the presence of high affinity (K4, 25-80 pM) and low affinity (Kd, 250-450 pM) components in adult tissues. Binding capacity was reduced 25-40% by incubation with pertussis toxin. Ontogenetic studies indicated that NT receptor capacity increased approximately 20-fold from the embryonic stage to adult. Cross-linking of 125I-NT to intact cells labeled one major band (52 kDa, > or = 90%) and two minor bands (40 and 90 kDa, < or = 10%) which could represent distinct NT-receptors or one receptor partly degraded or cross-linked to G-protein(s). The binding of 125I-NT to dispersed cells was enhanced by reduction with dithoithreitol and suppressed by alkylation with N-ethyl-maleimide (NEM), maleimidocaproic acid (MCA) and p-chloromercuribenzenesulfonate (PCMBS). Since MCA and PCMBS do not permeate cells, this suggests that the sulfhydryl group(s) critical to binding are located within the NT receptor itself. Preincubation of cells with NT prior to treatment with NEM diminished its inhibitory effect, suggesting that the critical SH-group(s) were within the NT binding pocket or were protected by an allosteric effect. These results suggest that one or more of the nine cysteine residues in the NT receptor is involved in the NT binding reaction.

Development of an enzyme-linked immunosorbent assay and a beta-1 adrenergic receptor-based assay for monitoring the drug atenolol.

PubMed

Sapir, A; Shalev, A Hariton; Skalka, N; Bronshtein, A; Altstein, M

2013-03-01

Two approaches for monitoring atenolol (ATL) were applied: an immunochemical assay and a competitive-binding assay, based on the interaction between ATL and its target receptor, β1 adrenergic receptor (β1AR). Polyclonal antibodies (Abs) for ATL were generated, and a highly specific microplate immunochemical assay, that is, an enzyme-linked immunosorbent assay (ELISA), for its detection was developed. The ATL ELISA exhibited I50 and limit of detection (I20) values of 0.15 ± 0.048 and 0.032 ± 0.016 ng/ml, respectively, and the Abs did not cross-react with any of the tested beta-blocker drugs. Furthermore, a human β1AR (h-β1AR) was stably expressed in Spodoptera frugiperda cells (Sf9). The receptor was employed to develop a competitive-binding assay that monitored binding of ATL in the presence of isoproteranol by quantification of secondary messenger, cyclic adenosine monophosphate (cAMP), levels in the transfected cells. The assay showed that the recombinant h-β1AR was functional, could bind the agonistic ligand isoproterenol as well as the antagonist ATL, as indicated by a dose-dependent elevation of cAMP in the presence of isoproteranol, and decrease after ATL addition. The highly efficient and sensitive ELISA and the receptor assay represent two methods suitable for efficient and cost-effective large-scale, high-throughput monitoring of ATL in environmental, agricultural, and biological samples. Copyright © 2012 SETAC.

Buprenorphine-elicited alteration of adenylate cyclase activity in human embryonic kidney 293 cells coexpressing κ-, μ-opioid and nociceptin receptors

PubMed Central

Wang, Pei-Chen; Ho, Ing-Kang; Lee, Cynthia Wei-Sheng

2015-01-01

Buprenorphine, a maintenance drug for heroin addicts, exerts its pharmacological function via κ- (KOP), μ-opioid (MOP) and nociceptin/opioid receptor-like 1 (NOP) receptors. Previously, we investigated its effects in an in vitro model expressing human MOP and NOP receptors individually or simultaneously (MOP, NOP, and MOP+NOP) in human embryonic kidney 293 cells. Here, we expanded this cell model by expressing human KOP, MOP and NOP receptors individually or simultaneously (KOP, KOP+MOP, KOP+NOP and KOP+MOP+NOP). Radioligand binding with tritium-labelled diprenorphine confirmed the expression of KOP receptors. Immunoblotting and immunocytochemistry indicated that the expressed KOP, MOP and NOP receptors are N-linked glycoproteins and colocalized in cytoplasmic compartments. Acute application of the opioid receptor agonists— U-69593, DAMGO and nociceptin— inhibited adenylate cyclase (AC) activity in cells expressing KOP, MOP and NOP receptors respectively. Buprenorphine, when applied acutely, inhibited AC activity to ~90% in cells expressing KOP+MOP+NOP receptors. Chronic exposure to buprenorphine induced concentration-dependent AC superactivation in cells expressing KOP+NOP receptors, and the level of this superactivation was even higher in KOP+MOP+NOP-expressing cells. Our study demonstrated that MOP receptor could enhance AC regulation in the presence of coexpressed KOP and NOP receptors, and NOP receptor is essential for concentration-dependent AC superactivation elicited by chronic buprenorphine exposure. PMID:26153065

ER phospholipid composition modulates lipogenesis during feeding and in obesity.

PubMed

Rong, Xin; Wang, Bo; Palladino, Elisa Nd; de Aguiar Vallim, Thomas Q; Ford, David A; Tontonoz, Peter

2017-10-02

Sterol regulatory element-binding protein 1c (SREBP-1c) is a central regulator of lipogenesis whose activity is controlled by proteolytic cleavage. The metabolic factors that affect its processing are incompletely understood. Here, we show that dynamic changes in the acyl chain composition of ER phospholipids affect SREBP-1c maturation in physiology and disease. The abundance of polyunsaturated phosphatidylcholine in liver ER is selectively increased in response to feeding and in the setting of obesity-linked insulin resistance. Exogenous delivery of polyunsaturated phosphatidylcholine to ER accelerated SREBP-1c processing through a mechanism that required an intact SREBP cleavage-activating protein (SCAP) pathway. Furthermore, induction of the phospholipid-remodeling enzyme LPCAT3 in response to liver X receptor (LXR) activation promoted SREBP-1c processing by driving the incorporation of polyunsaturated fatty acids into ER. Conversely, LPCAT3 deficiency increased membrane saturation, reduced nuclear SREBP-1c abundance, and blunted the lipogenic response to feeding, LXR agonist treatment, or obesity-linked insulin resistance. Desaturation of the ER membrane may serve as an auxiliary signal of the fed state that promotes lipid synthesis in response to nutrient availability.

Bisphenol A, Obesity, and Type 2 Diabetes Mellitus: Genuine Concern or Unnecessary Preoccupation?

PubMed Central

Mirmira, Priyadarshini; Evans-Molina, Carmella

2014-01-01

Bisphenol A or BPA is a ubiquitious industrial chemical found in a variety of plastic containers intended for food storage and in the epoxy resin linings of metal food and beverage cans, where it is used to prevent corrosion, food contamination, and spoilage. BPA has been recently linked to a wide variety of medical disorders and is known to have estrogenic activity with genomic as well as non-genomic estrogen-receptor mediated effects. Given rapidly increasing prevalence rates of metabolic disorders like obesity and Type 2 diabetes, BPA has recently come under intense scrutiny in scientific and lay communities as a potential endocrine disrupting compound with diabetogenic effects. The purpose of this review is to critically examine available literature investigating the link between BPA and alterations in metabolic health. Here, we discuss typical levels of exposure to BPA in daily life and analyze both epidemiological human data and mechanistic preclinical studies that have tested associations between BPA and obesity and diabetes. Finally, we summarize the current policies and views of national and international regulatory agencies regarding the safety of BPA use. PMID:24686036

Limbic striatal dopamine D2/3 receptor availability is associated with non-planning impulsivity in healthy adults after exclusion of potential dissimulators.

PubMed

Reeves, Suzanne J; Polling, Catherine; Stokes, Paul R A; Lappin, Julia M; Shotbolt, Paul P; Mehta, Mitul A; Howes, Oliver D; Egerton, Alice

2012-04-30

Positron emission tomography (PET) studies have reported an association between reduced striatal dopamine D2/3 receptor availability and higher scores on self-report measures of trait impulsivity in healthy adults. However, impulsivity is a multi-faceted construct, and it is unclear which aspect(s) of impulsivity might be driving these associations. The current study aimed to investigate the relationship between limbic (ventral) striatal D2/3 receptor availability and individual components of impulsivity (attentional, motor and non-planning) using the Barratt Impulsiveness Scale (BIS-11) and [(11)C]raclopride PET in 23 healthy volunteers. A partial correlational analysis showed a significant association between non-planning impulsiveness (lack of forethought or 'futuring') and limbic D2/3 receptor availability, which was only apparent after the exclusion of potential dissimulators (indexed by high scores on impression management). Our findings suggest that non-planning impulsiveness is associated with individual variation in limbic striatal D2/3 receptor availability and that different facets of impulsivity may have specific neurochemical correlates. Future studies that combine D2/3 receptor imaging with behavioral measures of impulsivity are required to further elucidate the precise relationship between individual components of trait impulsivity and brain dopaminergic function. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

A physical map of the human regulator of complement activation gene cluster linking the complement genes CR1, CR2, DAF, and C4BP

PubMed Central

1988-01-01

We report the organization of the human genes encoding the complement components C4-binding protein (C4BP), C3b/C4b receptor (CR1), decay accelerating factor (DAF), and C3dg receptor (CR2) within the regulator of complement activation (RCA) gene cluster. Using pulsed field gel electrophoresis analysis these genes have been physically linked and aligned as CR1-CR2-DAF-C4BP in an 800-kb DNA segment. The very tight linkage between the CR1 and the C4BP loci, contrasted with the relative long DNA distance between these genes, suggests the existence of mechanisms interfering with recombination within the RCA gene cluster. PMID:2450163

Disrupting the Amblyomma americanum (L.) CD147 receptor homolog prevents ticks from feeding to repletion and blocks spontaneous detachment of ticks from their host.

PubMed

Mulenga, Albert; Khumthong, Rabuesak

2010-07-01

The CD147 receptor is a cell-surface glycoprotein in the IgG family that plays pivotal roles in intercellular interactions involved with numerous physiological and pathological processes such as extracellular matrix remodeling. We previously found an Amblyomma americanum (Aam) tick CD147 receptor homolog among genes that were up regulated in response to tick feeding stimuli. This study characterizes an AamCD147 receptor protein that is 72-83% conserved in other tick species and possess characteristic CD147 receptor sequence features: an extracellular (EC) region containing two IgG domains, a transmembrane and the cytoplasmic domains. Likewise, the AamCD147 EC domain folds into secondary structures that are consistent to the human homolog: an amino-terminus beta-barrel that is linked to 2-carboxy-terminus beta-sheets with consensus disulfide bonds conserved in each of the 2 domains. CD147 receptor signaling and regulatory mechanisms are putatively conserved in ticks as revealed by in silico analysis that show presence in the tick genome of CD147 receptor signaling protein homologs, cyclophilin (CyP) A and B, and chaperones that transport it to the plasma membrane, caveolin-1 and CyP60. The AamCD147 receptor has a dichotomous expression pattern of where it is up regulated in response to feeding in the salivary gland but remains constant at the midgut and ovary levels suggesting that it may regulate different functions in different tick organs. We speculate that biological functions of the AamCD147 receptor are essential to tick feeding success as revealed by RNAi-mediated silencing that caused ticks to obtain smaller blood meals, of which approximately 69% were below threshold to trigger spontaneous detachment of ticks from the host. These ticks showed unusual cuticle tenderness and assumed a reddish coloration, a phenomenon that has been attributed to tick midgut damage allowing red blood cells to leak into tick hemolymph. On the basis of the CD147 receptor being linked to tissue growth regulation in mammals, we speculate that silencing of the AamCD147 receptor blocked progression of the tick intermolt growth, a process that precedes tick engorgement and their spontaneous detachment of from the host to end feeding. The results are discussed in context of advances in tick molecular physiology. 2010 Elsevier Ltd. All rights reserved.

Zika Virus Depletes Neural Progenitors in Human Cerebral Organoids through Activation of the Innate Immune Receptor TLR3.

PubMed

Dang, Jason; Tiwari, Shashi Kant; Lichinchi, Gianluigi; Qin, Yue; Patil, Veena S; Eroshkin, Alexey M; Rana, Tariq M

2016-08-04

Emerging evidence from the current outbreak of Zika virus (ZIKV) indicates a strong causal link between Zika and microcephaly. To investigate how ZIKV infection leads to microcephaly, we used human embryonic stem cell-derived cerebral organoids to recapitulate early stage, first trimester fetal brain development. Here we show that a prototype strain of ZIKV, MR766, efficiently infects organoids and causes a decrease in overall organoid size that correlates with the kinetics of viral copy number. The innate immune receptor Toll-like-Receptor 3 (TLR3) was upregulated after ZIKV infection of human organoids and mouse neurospheres and TLR3 inhibition reduced the phenotypic effects of ZIKV infection. Pathway analysis of gene expression changes during TLR3 activation highlighted 41 genes also related to neuronal development, suggesting a mechanistic connection to disrupted neurogenesis. Together, therefore, our findings identify a link between ZIKV-mediated TLR3 activation, perturbed cell fate, and a reduction in organoid volume reminiscent of microcephaly. Copyright © 2016 Elsevier Inc. All rights reserved.

Genetic forms of nephrogenic diabetes insipidus (NDI): Vasopressin receptor defect (X-linked) and aquaporin defect (autosomal recessive and dominant).

PubMed

Bichet, Daniel G; Bockenhauer, Detlef

2016-03-01

Nephrogenic diabetes insipidus (NDI), which can be inherited or acquired, is characterized by an inability to concentrate urine despite normal or elevated plasma concentrations of the antidiuretic hormone, arginine vasopressin (AVP). Polyuria with hyposthenuria and polydipsia are the cardinal clinical manifestations of the disease. About 90% of patients with congenital NDI are males with X-linked NDI who have mutations in the vasopressin V2 receptor (AVPR2) gene encoding the vasopressin V2 receptor. In less than 10% of the families studied, congenital NDI has an autosomal recessive or autosomal dominant mode of inheritance with mutations in the aquaporin-2 (AQP2) gene. When studied in vitro, most AVPR2 and AQP2 mutations lead to proteins trapped in the endoplasmic reticulum and are unable to reach the plasma membrane. Prior knowledge of AVPR2 or AQP2 mutations in NDI families and perinatal mutation testing is of direct clinical value and can avert the physical and mental retardation associated with repeated episodes of dehydration. Copyright © 2016 Elsevier Ltd. All rights reserved.

PKCθ links proximal T cell and Notch signaling through localized regulation of the actin cytoskeleton

PubMed Central

Britton, Graham J; Ambler, Rachel; Clark, Danielle J; Hill, Elaine V; Tunbridge, Helen M; McNally, Kerrie E; Burton, Bronwen R; Butterweck, Philomena; Sabatos-Peyton, Catherine; Hampton-O’Neil, Lea A; Verkade, Paul; Wülfing, Christoph; Wraith, David Cameron

2017-01-01

Notch is a critical regulator of T cell differentiation and is activated through proteolytic cleavage in response to ligand engagement. Using murine myelin-reactive CD4 T cells, we demonstrate that proximal T cell signaling modulates Notch activation by a spatiotemporally constrained mechanism. The protein kinase PKCθ is a critical mediator of signaling by the T cell antigen receptor and the principal costimulatory receptor CD28. PKCθ selectively inactivates the negative regulator of F-actin generation, Coronin 1A, at the center of the T cell interface with the antigen presenting cell (APC). This allows for effective generation of the large actin-based lamellum required for recruitment of the Notch-processing membrane metalloproteinase ADAM10. Such enhancement of Notch activation is critical for efficient T cell proliferation and Th17 differentiation. We reveal a novel mechanism that, through modulation of the cytoskeleton, controls Notch activation at the T cell:APC interface thereby linking T cell receptor and Notch signaling pathways. DOI: http://dx.doi.org/10.7554/eLife.20003.001 PMID:28112644

Roles for SH2 and SH3 domains in Lyn kinase association with activated FcepsilonRI in RBL mast cells revealed by patterned surface analysis.

PubMed

Hammond, Stephanie; Wagenknecht-Wiesner, Alice; Veatch, Sarah L; Holowka, David; Baird, Barbara

2009-10-01

In mast cells, antigen-mediated cross-linking of IgE bound to its high-affinity surface receptor, FcepsilonRI, initiates a signaling cascade that culminates in degranulation and release of allergic mediators. Antigen-patterned surfaces, in which the antigen is deposited in micron-sized features on a silicon substrate, were used to examine the spatial relationship between clustered IgE-FcepsilonRI complexes and Lyn, the signal-initiating tyrosine kinase. RBL mast cells expressing wild-type Lyn-EGFP showed co-redistribution of this protein with clustered IgE receptors on antigen-patterned surfaces, whereas Lyn-EGFP containing an inhibitory point mutation in its SH2 domain did not significantly accumulate with the patterned antigen, and Lyn-EGFP with an inhibitory point mutation in its SH3 domain exhibited reduced interactions. Our results using antigen-patterned surfaces and quantitative cross-correlation image analysis reveal that both the SH2 and SH3 domains contribute to interactions between Lyn kinase and cross-linked IgE receptors in stimulated mast cells.

Post-Translational Modification Biology of Glutamate Receptors and Drug Addiction

PubMed Central

Mao, Li-Min; Guo, Ming-Lei; Jin, Dao-Zhong; Fibuch, Eugene E.; Choe, Eun Sang; Wang, John Q.

2011-01-01

Post-translational covalent modifications of glutamate receptors remain a hot topic. Early studies have established that this family of receptors, including almost all ionotropic and metabotropic glutamate receptor subtypes, undergoes active phosphorylation at serine, threonine, or tyrosine residues in their intracellular domains. Recent evidence identifies several glutamate receptor subtypes to be direct substrates for palmitoylation at cysteine residues. Other modifications such as ubiquitination and sumoylation at lysine residues also occur to certain glutamate receptors. These modifications are dynamic and reversible in nature and are regulatable by changing synaptic inputs. The regulated modifications significantly impact the receptor in many ways, including interrelated changes in biochemistry (synthesis, subunit assembling, and protein–protein interactions), subcellular redistribution (trafficking, endocytosis, synaptic delivery, and clustering), and physiology, usually associated with changes in synaptic plasticity. Glutamate receptors are enriched in the striatum and cooperate closely with dopamine to regulate striatal signaling. Emerging evidence shows that modification processes of striatal glutamate receptors are sensitive to addictive drugs, such as psychostimulants (cocaine and amphetamine). Altered modifications are believed to be directly linked to enduring receptor/synaptic plasticity and drug-seeking. This review summarizes several major types of modifications of glutamate receptors and analyzes the role of these modifications in striatal signaling and in the pathogenesis of psychostimulant addiction. PMID:21441996

Emergence of the A20/ABIN-mediated inhibition of NF-κB signaling via modifying the ubiquitinated proteins in a basal chordate.

PubMed

Yuan, Shaochun; Dong, Xiangru; Tao, Xin; Xu, Liqun; Ruan, Jie; Peng, Jian; Xu, Anlong

2014-05-06

In the past decade, ubiquitination has been well documented to have multifaceted roles in regulating NF-κB activation in mammals. However, its function, especially how deubiquitinating enzymes balance the NF-κB activation, remains largely elusive in invertebrates. Investigating bbtA20 and its binding proteins, bbt A20-binding inhibitor of NF-κB (bbtABIN1) and bbtABIN2, in Chinese amphioxus Branchiostoma belcheri tsingtauense, we found that bbtABIN2 can colocalize and compete with bbt TNF receptor-associated factor 6 to connect the K63-linked polyubiquitin chains, whereas bbtABIN1 physically links bbtA20 to bbt NF-κB essential modulator (bbtNEMO) to facilitate the K48-linked ubiquitination of bbtNEMO. Similar to human A20, bbtA20 is a dual enzyme that removes the K63-linked polyubiquitin chains and builds the K48-linked polyubiquitin chains on bbt receptor-interacting serine/threonine protein kinase 1b, leading to the inhibition of NF-κB signaling. Our study not only suggests that ubiquitination is an ancient strategy in regulating NF-κB activation but also provides the first evidence, to our knowledge, for ABINs/A20-mediated inhibition of NF-κB via modifying the ubiquitinated proteins in a basal chordate, adding information on the stepwise development of vertebrate innate immune signaling.

Molecular basis for the unique deubiquitinating activity of the NF-kappaB inhibitor A20.

PubMed

Lin, Su-Chang; Chung, Jee Y; Lamothe, Betty; Rajashankar, Kanagalaghatta; Lu, Miao; Lo, Yu-Chih; Lam, Amy Y; Darnay, Bryant G; Wu, Hao

2008-02-15

Nuclear factor kappaB (NF-kappaB) activation in tumor necrosis factor, interleukin-1, and Toll-like receptor pathways requires Lys63-linked nondegradative polyubiquitination. A20 is a specific feedback inhibitor of NF-kappaB activation in these pathways that possesses dual ubiquitin-editing functions. While the N-terminal domain of A20 is a deubiquitinating enzyme (DUB) for Lys63-linked polyubiquitinated signaling mediators such as TRAF6 and RIP, its C-terminal domain is a ubiquitin ligase (E3) for Lys48-linked degradative polyubiquitination of the same substrates. To elucidate the molecular basis for the DUB activity of A20, we determined its crystal structure and performed a series of biochemical and cell biological studies. The structure reveals the potential catalytic mechanism of A20, which may be significantly different from papain-like cysteine proteases. Ubiquitin can be docked onto a conserved A20 surface; this interaction exhibits charge complementarity and no steric clash. Surprisingly, A20 does not have specificity for Lys63-linked polyubiquitin chains. Instead, it effectively removes Lys63-linked polyubiquitin chains from TRAF6 without dissembling the chains themselves. Our studies suggest that A20 does not act as a general DUB but has the specificity for particular polyubiquitinated substrates to assure its fidelity in regulating NF-kappaB activation in the tumor necrosis factor, interleukin-1, and Toll-like receptor pathways.

PSM/SH2-B distributes selected mitogenic receptor signals to distinct components in the PI3-kinase and MAP kinase signaling pathways.

PubMed

Deng, Youping; Xu, Hu; Riedel, Heimo

2007-02-15

The Pro-rich, PH, and SH2 domain containing mitogenic signaling adapter PSM/SH2-B has been implicated as a cellular partner of various mitogenic receptor tyrosine kinases and related signaling mechanisms. Here, we report in a direct comparison of three peptide hormones, that PSM participates in the assembly of distinct mitogenic signaling complexes in response to insulin or IGF-I when compared to PDGF in cultured normal fibroblasts. The complex formed in response to insulin or IGF-I involves the respective peptide hormone receptor and presumably the established components leading to MAP kinase activation. However, our data suggest an alternative link from the PDGF receptor via PSM directly to MEK1/2 and consequently also to p44/42 activation, possibly through a scaffold protein. At least two PSM domains participate, the SH2 domain anticipated to link PSM to the respective receptor and the Pro-rich region in an association with an unidentified downstream component resulting in direct MEK1/2 and p44/42 regulation. The PDGF receptor signaling complex formed in response to PDGF involves PI 3-kinase in addition to the same components and interactions as described for insulin or IGF-I. PSM associates with PI 3-kinase via p85 and in addition the PSM PH domain participates in the regulation of PI 3-kinase activity, presumably through membrane interaction. In contrast, the PSM Pro-rich region appears to participate only in the MAP kinase signal. Both pathways contribute to the mitogenic response as shown by cell proliferation, survival, and focus formation. PSM regulates p38 MAP kinase activity in a pathway unrelated to the mitogenic response.

The GIT–PIX complexes regulate the chemotactic response of rat basophilic leukaemia cells

PubMed Central

Gavina, Manuela; Za, Lorena; Molteni, Raffaella; Pardi, Ruggero; Curtis, Ivan de

2009-01-01

Background information. Cell motility entails the reorganization of the cytoskeleton and membrane trafficking for effective protrusion. The GIT–PIX protein complexes are involved in the regulation of cell motility and adhesion and in the endocytic traffic of members of the family of G-protein-coupled receptors. We have investigated the function of the endogenous GIT complexes in the regulation of cell motility stimulated by fMLP (formyl-Met-Leu-Phe) peptide, in a rat basophilic leukaemia RBL-2H3 cell line stably expressing an HA (haemagglutinin)-tagged receptor for the fMLP peptide. Results. Our analysis shows that RBL cells stably transfected with the chemoattractant receptor expressed both GIT1–PIX and GIT2–PIX endogenous complexes. We have used silencing of the different members of the complex by small interfering RNAs to study the effects on a number of events linked to agonist-induced cell migration. We found that cell adhesion was not affected by depletion of any of the proteins of the GIT complex, whereas agonist-enhanced cell spreading was inhibited. Analysis of agonist-stimulated haptotactic cell migration indicated a specific positive effect of GIT1 depletion on trans-well migration. The internalization of the formyl-peptide receptor was also inhibited by depletion of GIT1 and GIT2. The effects of the GIT complexes on trafficking of the receptors was confirmed by an antibody-enhanced agonist-induced internalization assay, showing that depletion of PIX, GIT1 or GIT2 protein caused decreased perinuclear accumulation of internalized receptors. Conclusions. Our results show that endogenous GIT complexes are involved in the regulation of chemoattractant-induced cell motility and receptor trafficking, and support previous findings indicating an important function of the GIT complexes in the regulation of different G-protein-coupled receptors. Our results also indicate that endogenous GIT1 and GIT2 regulate distinct subsets of agonist-induced responses and suggest a possible functional link between the control of receptor trafficking and the regulation of cell motility by GIT proteins. PMID:19912111

In vitro profiling of toxic effects of prominent environmental lower-chlorinated PCB congeners linked with endocrine disruption and tumor promotion.

PubMed

Pěnčíková, Kateřina; Svržková, Lucie; Strapáčová, Simona; Neča, Jiří; Bartoňková, Iveta; Dvořák, Zdeněk; Hýžďalová, Martina; Pivnička, Jakub; Pálková, Lenka; Lehmler, Hans-Joachim; Li, Xueshu; Vondráček, Jan; Machala, Miroslav

2018-06-01

The mechanisms contributing to toxic effects of airborne lower-chlorinated PCB congeners (LC-PCBs) remain poorly characterized. We evaluated in vitro toxicities of environmental LC-PCBs found in both indoor and outdoor air (PCB 4, 8, 11, 18, 28 and 31), and selected hydroxylated metabolites of PCB 8, 11 and 18, using reporter gene assays, as well as other functional cellular bioassays. We focused on processes linked with endocrine disruption, tumor promotion and/or regulation of transcription factors controlling metabolism of both endogenous compounds and xenobiotics. The tested LC-PCBs were found to be mostly efficient anti-androgenic (within nanomolar - micromolar range) and estrogenic (at micromolar concentrations) compounds, as well as inhibitors of gap junctional intercellular communication (GJIC) at micromolar concentrations. PCB 8, 28 and 31 were found to partially inhibit the aryl hydrocarbon receptor (AhR)-mediated activity. The tested LC-PCBs were also partial constitutive androstane receptor (CAR) and pregnane X receptor (PXR) agonists, with PCB 4, 8 and 18 being the most active compounds. They were inactive towards other nuclear receptors, such as vitamin D receptor, thyroid receptor α, glucocorticoid receptor or peroxisome proliferator-activated receptor γ. We found that only PCB 8 contributed to generation of oxidative stress, while all tested LC-PCBs induced arachidonic acid release (albeit without further modulations of arachidonic acid metabolism) in human lung epithelial cells. Importantly, estrogenic effects of hydroxylated (OH-PCB) metabolites of LC-PCBs (4-OH-PCB 8, 4-OH-PCB 11 and 4'-OH-PCB 18) were higher than those of the parent PCBs, while their other toxic effects were only slightly altered or suppressed. This suggested that metabolism may alter toxicity profiles of LC-PCBs in a receptor-specific manner. In summary, anti-androgenic and estrogenic activities, acute inhibition of GJIC and suppression of the AhR-mediated activity were found to be the most relevant modes of action of airborne LC-PCBs, although they partially affected also additional cellular targets. Copyright © 2018 Elsevier Ltd. All rights reserved.

Covalent binding of C3b to tetanus toxin: influence on uptake/internalization of antigen by antigen-specific and non-specific B cells.

PubMed Central

Villiers, M B; Villiers, C L; Jacquier-Sarlin, M R; Gabert, F M; Journet, A M; Colomb, M G

1996-01-01

Antigen opsonization by the C3b fragment of complement is a significant event in the modulation of cell-mediated immune response, but its mechanism is still largely unknown. The structural characteristics of C3b allow it to act as a bifunctional ligand between antigen and cells via their membrane C3b receptors. It was thus of interest to study the influence of the covalent link between C3b and antigen on the fixation and internalization of this antigen by antigen-presenting cells. Tetanus toxin (TT) was used as antigen, either free or covalently linked to C3b (TT-C3b). The antigen-presenting cells were TT-specific (4.2) or non-specific (BL15) Epstein-Barr virus (EBV)-transformed B cells. C3b was found to play an important role in antigen fixation and internalization by both antigen-specific and antigen non-specific cells. Covalent binding of C3b on TT (1) permitted fixation and internalization of this antigen by non-specific cells via their complement receptors; (2) enhanced antigen fixation and resulted in cross-linking between membrane immunoglobulins and complement receptors on antigen-specific cells. The consequences of covalent C3b binding to TT were analysed using antigen-specific and antigen-nonspecific cells. In both cases, a net increase in antigen fixation was observed. At the intracellular level, covalent C3b binding to TT resulted in a large TT incorporation in endosomes of nonspecific cells, similar to that observed in antigen-specific cells. Thus, C3b covalently linked to antigen enlarges the array of B-cell types capable of presenting antigen, including non-specific cells. Images Figure 2 PMID:8958046

CNS syndromes associated with antibodies against metabotropic receptors.

PubMed

Lancaster, Eric

2017-06-01

Autoantibodies to Central nervous system (CNS) metabotropic receptors are associated with a growing family of autoimmune brain diseases, including encephalitis, basal ganglia encephalitis, Ophelia syndrome, and cerebellitis. The purpose of this review is to summarize the state of knowledge regarding the target receptors, the neurological autoimmune disorders, and the pathogenic mechanisms. Antibodies to the γ-aminobutyric acid B receptor are associate with limbic encephalitis and severe seizures, often with small cell lung cancers. Metabotropic glutamate receptor 5 (mGluR5) antibodies associate with Ophelia syndrome, a relatively mild form of encephalitis linked to Hodgkin lymphoma. mGluR1 antibodies associate with a form of cerebellar degeneration, and also Hodgkin lymphoma. Antibodies to Homer 3, a protein associated with mGluR1, have also been reported in two patients with cerebellar syndromes. Dopamine-2 receptor antibodies have been reported by one group in children with basal ganglia encephalitis and other disorders. CNS metabotropic receptor antibodies may exert direct inhibitory effects on their target receptors, but the evidence is more limited than with autoantibodies to ionotropic glutamate receptors. In the future, improved recognition of these patients may lead to better outcomes. Understanding the molecular mechanisms of the diseases may uncover novel treatment strategies.

Negative Cooperativity in the EGF Receptor

PubMed Central

Pike, Linda J.

2012-01-01

Scatchard analyses of the binding of EGF to its receptor yield concave up Scatchard plots, indicative of some type of heterogenity in ligand binding affinity. This was typically interpreted as being due to the presence of two independent binding site–one of high affinity representing ≤10% of the receptor population and one of low affinity making up the bulk of the receptors. However, the concept of two independent binding sites is difficult to reconcile with the X-ray structures of the dimerized EGF receptor that show symmetric binding of the two ligands. A new approach to the analysis of 125I-EGF binding data combined with the structure of the singly-occupied Drosophila EGF receptor have now shown that this heterogeneity is due to the presence of negative cooperativity in the EGF receptor. Concerns that negative cooperativity precludes ligand-induced dimerization of the EGF receptor confuse the concepts of linkage cooperativity. Linkage refers to the effect of ligand on the assembly of dimers while cooperativity refers to the effect of ligand binding to one subunit on ligand binding to the other subunit within a preassembled dimer. Binding of EGF to its receptor is positively linked with dimer assembly but shows negative cooperativity within the dimer. PMID:22260659

Regulators of Androgen Action Resource: a one-stop shop for the comprehensive study of androgen receptor action.

PubMed

DePriest, Adam D; Fiandalo, Michael V; Schlanger, Simon; Heemers, Frederike; Mohler, James L; Liu, Song; Heemers, Hannelore V

2016-01-01

Androgen receptor (AR) is a ligand-activated transcription factor that is the main target for treatment of non-organ-confined prostate cancer (CaP). Failure of life-prolonging AR-targeting androgen deprivation therapy is due to flexibility in steroidogenic pathways that control intracrine androgen levels and variability in the AR transcriptional output. Androgen biosynthesis enzymes, androgen transporters and AR-associated coregulators are attractive novel CaP treatment targets. These proteins, however, are characterized by multiple transcript variants and isoforms, are subject to genomic alterations, and are differentially expressed among CaPs. Determining their therapeutic potential requires evaluation of extensive, diverse datasets that are dispersed over multiple databases, websites and literature reports. Mining and integrating these datasets are cumbersome, time-consuming tasks and provide only snapshots of relevant information. To overcome this impediment to effective, efficient study of AR and potential drug targets, we developed the Regulators of Androgen Action Resource (RAAR), a non-redundant, curated and user-friendly searchable web interface. RAAR centralizes information on gene function, clinical relevance, and resources for 55 genes that encode proteins involved in biosynthesis, metabolism and transport of androgens and for 274 AR-associated coregulator genes. Data in RAAR are organized in two levels: (i) Information pertaining to production of androgens is contained in a 'pre-receptor level' database, and coregulator gene information is provided in a 'post-receptor level' database, and (ii) an 'other resources' database contains links to additional databases that are complementary to and useful to pursue further the information provided in RAAR. For each of its 329 entries, RAAR provides access to more than 20 well-curated publicly available databases, and thus, access to thousands of data points. Hyperlinks provide direct access to gene-specific entries in the respective database(s). RAAR is a novel, freely available resource that provides fast, reliable and easy access to integrated information that is needed to develop alternative CaP therapies. Database URL: http://www.lerner.ccf.org/cancerbio/heemers/RAAR/search/. © The Author(s) 2016. Published by Oxford University Press.

Genomic profiling of tumor necrosis factor alpha (TNF-alpha) receptor and interleukin-1 receptor knockout mice reveals a link between TNF-alpha signaling and increased severity of 1918 pandemic influenza virus infection

USDA-ARS?s Scientific Manuscript database

The influenza pandemic of 1918-1919 was one of the worst global pandemics in recent history. The highly pathogenic nature of the 1918 virus is thought to be mediated in part by a dysregulation of the host response, including an exacerbated pro-inflammatory cytokine response. In the present study, we...

The shape of things to come.

PubMed

Akin, Orkun; Zipursky, S Lawrence

2014-01-16

Surface receptors can link binding of ligands to changes in the actin-based cell cytoskeleton. Chia et al. and Chen et al. provide evidence for direct binding between the cytoplasmic tails of receptors and the WAVE complex, a regulator of the actin nucleator Arp2/3 complex, which might help to explain how environmental signals are translated into changes in morphology and motility. Copyright © 2014 Elsevier Inc. All rights reserved.

[Mucosal immunity with emphasis on urinary tract immunity and diabetes].

PubMed

Krejsek, J; Kudlová, M; Kolácková, M; Novosad, J

2008-05-01

Protective immune response in urinary tract is frequently impaired in patients with diabetes. Immunity in this mucosal compartment displays unique characteristics; e.g. absence of physiological microflora and lack of mucus. Pathogens are identified by the PRR receptors expressed on both epithelial and immune cells. Inflammatory response characterised by the acumulation ofgranulocytes is followed. Both protective and harm characteristics of inflammatory response are inseparable linked and delineated by gene polymorphisms in PRR receptors.

Correlation of stable elevations in striatal mu-opioid receptor availability in detoxified alcoholic patients with alcohol craving: a positron emission tomography study using carbon 11-labeled carfentanil.

PubMed

Heinz, Andreas; Reimold, Matthias; Wrase, Jana; Hermann, Derik; Croissant, Bernhard; Mundle, Götz; Dohmen, Bernhard M; Braus, Dieter F; Braus, Dieter H; Schumann, Gunter; Machulla, Hans-Jürgen; Bares, Roland; Mann, Karl

2005-01-01

The pleasant effects of food and alcohol intake are partially mediated by mu-opiate receptors in the ventral striatum, a central area of the brain reward system. Blockade of mu-opiate receptors with naltrexone reduces the relapse risk among some but not all alcoholic individuals. To test the hypothesis that alcohol craving is pronounced among alcoholic individuals with a high availability of mu-opiate receptors in the brain reward system. Patients and comparison sample. The availability of central mu-opiate receptors was measured in vivo with positron emission tomography (PET) and the radioligand carbon 11-labeled carfentanil in the ventral striatum and compared with the severity of alcohol craving as assessed by the Obsessive Compulsive Drinking Scale (OCDS). Hospitalized care. Volunteer sample of 25 male alcohol-dependent inpatients assessed after detoxification of whom 12 underwent PET again 5 weeks later. Control group of 10 healthy men. After 1 to 3 weeks of abstinence, the availability of mu-opiate receptors in the ventral striatum, including the nucleus accumbens, was significantly elevated in alcoholic patients compared with healthy controls and remained elevated when 12 alcoholic patients had these levels measured 5 weeks later (P<.05 corrected for multiple testing). Higher availability of mu-opiate receptors in this brain area correlated significantly with the intensity of alcohol craving as assessed by the OCDS. Abstinent alcoholic patients displayed an increase in mu-opiate receptors in the ventral striatum, including the nucleus accumbens, which correlated with the severity of alcohol craving. These findings point to a neuronal correlate of alcohol urges.

Striatal dopamine D2/3 receptor-mediated neurotransmission in major depression: Implications for anhedonia, anxiety and treatment response.

PubMed

Peciña, Marta; Sikora, Magdalena; Avery, Erich T; Heffernan, Joseph; Peciña, Susana; Mickey, Brian J; Zubieta, Jon-Kar

2017-10-01

Dopamine (DA) neurotransmission within the brain's reward circuit has been implicated in the pathophysiology of depression and in both, cognitive and pharmacological mechanisms of treatment response. Still, a direct relationship between measures of DA neurotransmission and reward-related deficits in patients with depression has not been demonstrated. To gain insight into the symptom-specific alterations in the DA system in patients with depression, we used positron emission tomography (PET) and the D 2/3 receptor-selective radiotracer [ 11 C]raclopride in twenty-three non-smoking un-medicated Major Depressive Disorder (MDD) patients and sixteen healthy controls (HC). We investigated the relationship between D 2/3 receptor availability and baseline measures of depression severity, anxiety, anhedonia, and cognitive and pharmacological mechanisms of treatment response. We found that, compared to controls, patients with depression showed greater D 2/3 receptor availability in several striatal regions, including the bilateral ventral pallidum/nucleus accumbens (vPAL/NAc), and the right ventral caudate and putamen. In the depressed sample, D 2/3 receptor availability in the caudal portion of the ventral striatum (NAc/vPAL) correlated with higher anxiety symptoms, whereas D 2/3 receptor availability in the rostral area of the ventral striatum correlated negatively with the severity of motivational anhedonia. Finally, MDD non-remitters showed greater baseline anxiety, greater D 2/3 availability in the NAc/vPAL, and greater placebo-induced DA release in the bilateral NAc. Our results demonstrate abnormally high D 2/3 receptor availability in the ventral striatum of patients with MDD, which seem to be associated with comorbid anxiety symptoms and lack of response to antidepressants. Copyright © 2017 Elsevier B.V. and ECNP. All rights reserved.

Nitrosative stress uncovers potent β2-adrenergic receptor-linked vasodilation further enhanced by blockade of clathrin endosome formation.

PubMed

Frame, Mary D; Dewar, Anthony M; Calizo, Rhodora C; Qifti, Androniqi; Scarlata, Suzanne F

2018-06-01

This study investigated the effect of sodium nitroprusside (SNP) preexposure on vasodilation via the β-adrenergic receptor (BAR) system. SNP was used as a nitrosative/oxidative proinflammatory insult. Small arterioles were visualized by intravital microscopy in the hamster cheek pouch tissue (isoflurane, n = 45). Control dilation to isoproterenol (EC 50 : 10 -7 mol/l) became biphasic as a function of concentration after 2 min of exposure to SNP (10 -4 M), with increased potency at picomolar dilation uncovered and decreased efficacy at the micromolar dilation. Control dilation to curcumin was likewise altered after SNP, but only the increased potency at a low dose was uncovered, whereas micromolar dilation was eliminated. The picomolar dilations were blocked by the potent BAR-2 inverse agonist carazolol (10 -9 mol/l). Dynamin inhibition with dynasore mimicked this effect, suggesting that SNP preexposure prevented BAR agonist internalization. Using HeLa cells transfected with BAR-2 tagged with monomeric red fluorescent protein, exposure to 10 -8 -10 -6 mol/l curcumin resulted in internalization and colocalization of BAR-2 and curcumin (FRET) that was prevented by oxidative stress (10 -3 mol/l CoCl 2 ), supporting that stress prevented internalization of the BAR agonist with the micromolar agonist. This study presents novel data supporting that distinct pools of BARs are differentially available after inflammatory insult. NEW & NOTEWORTHY Preexposure to an oxidative/nitrosative proinflammatory insult provides a "protective preconditioning" against future oxidative damage. We examined immediate vasoactive and molecular consequences of a brief preexposure via β-adrenergic receptor signaling in small arterioles. Blocked receptor internalization with elevated reactive oxygen levels coincides with a significant and unexpected vasodilation to β-adrenergic agonists at picomolar doses.

Glycyrrhetinic acid and E.resveratroloside act as potential plant derived compounds against dopamine receptor D3 for Parkinson’s disease: a pharmacoinformatics study

PubMed Central

Mirza, Muhammad Usman; Mirza, A Hammad; Ghori, Noor-Ul-Huda; Ferdous, Saba

2015-01-01

Parkinson’s disease (PD) is caused by loss in nigrostriatal dopaminergic neurons and is ranked as the second most common neurodegenerative disorder. Dopamine receptor D3 is considered as a potential target in drug development against PD because of its lesser side effects and higher degree of neuro-protection. One of the prominent therapies currently available for PD is the use of dopamine agonists which mimic the natural action of dopamine in the brain and stimulate dopamine receptors directly. Unfortunately, use of these pharmacological therapies such as bromocriptine, apomorphine, and ropinirole provides only temporary relief of the disease symptoms and is frequently linked with insomnia, anxiety, depression, and agitation. Thus, there is a need for an alternative treatment that not only hinders neurodegeneration, but also has few or no side effects. Since the past decade, much attention has been given to exploitation of phytochemicals and their use in alternative medicine research. This is because plants are a cheap, indispensable, and never ending resource of active compounds that are beneficial against various diseases. In the current study, 40 active phytochemicals against PD were selected through literature survey. These ligands were docked with dopamine receptor D3 using AutoDock and AutoDockVina. Binding energies were compared to docking results of drugs approved by the US Food and Drug Administration against PD. The compounds were further analyzed for their absorption, distribution, metabolism, and excretion-toxicity profile. From the study it is concluded that glycyrrhetinic acid and E.resveratroloside are potent compounds having high binding energies which should be considered as potential lead compounds for drug development against PD. PMID:25565772

Glycyrrhetinic acid and E.resveratroloside act as potential plant derived compounds against dopamine receptor D3 for Parkinson's disease: a pharmacoinformatics study.

PubMed

Mirza, Muhammad Usman; Mirza, A Hammad; Ghori, Noor-Ul-Huda; Ferdous, Saba

2015-01-01

Parkinson's disease (PD) is caused by loss in nigrostriatal dopaminergic neurons and is ranked as the second most common neurodegenerative disorder. Dopamine receptor D3 is considered as a potential target in drug development against PD because of its lesser side effects and higher degree of neuro-protection. One of the prominent therapies currently available for PD is the use of dopamine agonists which mimic the natural action of dopamine in the brain and stimulate dopamine receptors directly. Unfortunately, use of these pharmacological therapies such as bromocriptine, apomorphine, and ropinirole provides only temporary relief of the disease symptoms and is frequently linked with insomnia, anxiety, depression, and agitation. Thus, there is a need for an alternative treatment that not only hinders neurodegeneration, but also has few or no side effects. Since the past decade, much attention has been given to exploitation of phytochemicals and their use in alternative medicine research. This is because plants are a cheap, indispensable, and never ending resource of active compounds that are beneficial against various diseases. In the current study, 40 active phytochemicals against PD were selected through literature survey. These ligands were docked with dopamine receptor D3 using AutoDock and AutoDockVina. Binding energies were compared to docking results of drugs approved by the US Food and Drug Administration against PD. The compounds were further analyzed for their absorption, distribution, metabolism, and excretion-toxicity profile. From the study it is concluded that glycyrrhetinic acid and E.resveratroloside are potent compounds having high binding energies which should be considered as potential lead compounds for drug development against PD.

FcgammaRIIB signals inhibit BLyS signaling and BCR-mediated BLyS receptor up-regulation.

PubMed

Crowley, Jenni E; Stadanlick, Jason E; Cambier, John C; Cancro, Michael P

2009-02-12

These studies investigate how interactions between the BCR and FcgammaRIIB affect B lymphocyte stimulator (BLyS) recep-tor expression and signaling. Previous studies showed that BCR ligation up-regulates BLyS binding capacity in mature B cells, reflecting increased BLyS receptor levels. Here we show that FcgammaRIIB coaggregation dampens BCR-induced BLyS receptor up-regulation. This cross-regulation requires BCR and FcgammaRIIB coligation, and optimal action relies on the Src-homology-2 (SH2)-containing inositol 5 phosphase-1 (SHIP1). Subsequent to FcgammaRIIB/BCR coaggregation, the survival promoting actions of BLyS are attenuated, reflecting reduced BLyS receptor signaling capacity in terms of Pim 2 maintenance, noncanonical NF-kappaB activation, and Bcl-xL levels. These findings link the negative regulatory functions of FcgammaRIIB with BLyS-mediated B-cell survival.

The identification of N-linked oligosaccharides on the human CR2/Epstein-Barr virus receptor and their function in receptor metabolism, plasma membrane expression, and ligand binding.

PubMed

Weis, J J; Fearon, D T

1985-11-05

Human complement receptor type 2 (CR2) was biosynthetically labeled by pulsing SB B lymphoblastoid cells for 25 min with [35S]methionine followed by chase in the presence of excess unlabeled methionine. An Mr 134,000 polypeptide represented the major form of the receptor at the end of the pulse period, and within 1 h of chase this disappeared coincident with the appearance of the Mr 145,000 mature form of CR2. Precursor, but not mature, CR2 was sensitive to endoglycosidase H, indicating that maturation of CR2 represented processing of N-linked high mannose oligosaccharides to the complex type. The processing of precursor CR2 was impaired by monensin. In the presence of tunicamycin an Mr 111,000 form of CR2 was synthesized by SB cells, and this did not chase into either precursor or mature CR2. This Mr 111,000 form of CR2 did not incorporate [3H]glucosamine, indicating that it lacked both N- and O-linked oligosaccharide. The half-lives of mature CR2 and nonglycosylated CR2 pulse-labeled in the presence of tunicamycin were 13.8 and 2.8 h, respectively; the turnover rate of B1, a membrane protein normally lacking carbohydrate, was unaffected by the presence of the antibiotic. The percentage of pulse-labeled, nonglycosylated CR2 that was expressed at the cell surface after 1 h of chase in the presence of tunicamycin was 30%, identical to that of mature CR2 in cells chased in the absence of the antibiotic. However, after 6 h of chase there was no additional net accumulation of nonglycosylated CR2 at the plasma membrane, while the proportion of pulse-labeled mature CR2 at this site had risen to 81%. Therefore, N-linked oligosaccharides are essential for the stability of CR2 and have some role in its plasma membrane expression. In contrast, the observation that all three forms of CR2 bound to Sepharose C3 indicates that oligosaccharides are not necessary for the interaction between CR2 and its complement ligand.

The impacts of neutralized acid mine drainage contaminated water on the expression of selected endocrine-linked genes in juvenile Mozambique tilapia Oreochromis mossambicus exposed in vivo.

PubMed

Truter, Johannes Christoff; va Wyk, Johannes Hendrik; Oberholster, Paul Johan; Botha, Anna-Maria

2014-02-01

Acid mine drainage (AMD) is a global environmental concern due to detrimental impacts on river ecosystems. Little is however known regarding the biological impacts of neutralized AMD on aquatic vertebrates despite excessive discharge into watercourses. The aim of this investigation was to evaluate the endocrine modulatory potential of neutralized AMD, using molecular biomarkers in the teleost fish Oreochromis mossambicus in exposure studies. Surface water was collected from six locations downstream of a high density sludge (HDS) AMD treatment plant and a reference site unimpacted by AMD. The concentrations of 28 elements, including 22 metals, were quantified in the exposure water in order to identify potential links to altered gene expression. Relatively high concentrations of manganese (~ 10mg/l), nickel (~ 0.1mg/l) and cobalt (~ 0.03 mg/l) were detected downstream of the HDS plant. The expression of thyroid receptor-α (trα), trβ, androgen receptor-1 (ar1), ar2, glucocorticoid receptor-1 (gr1), gr2, mineralocorticoid receptor (mr) and aromatase (cyp19a1b) was quantified in juvenile fish after 48 h exposure. Slight but significant changes were observed in the expression of gr1 and mr in fish exposed to water collected directly downstream of the HDS plant, consisting of approximately 95 percent neutralized AMD. The most pronounced alterations in gene expression (i.e. trα, trβ, gr1, gr2, ar1 and mr) was associated with water collected further downstream at a location with no other apparent contamination vectors apart from the neutralized AMD. The altered gene expression associated with the "downstream" locality coincided with higher concentrations of certain metals relative to the locality adjacent to the HDS plant which may indicate a causative link. The current study provides evidence of endocrine disruptive activity associated with neutralized AMD contamination in regard to alterations in the expression of key genes linked to the thyroid, interrenal and gonadal endocrine axes of a teleost fish species. © 2013 Published by Elsevier Inc.

Oxime Ethers of (E)-11-Isonitrosostrychnine as Highly Potent Glycine Receptor Antagonists.

PubMed

Mohsen, Amal M Y; Mandour, Yasmine M; Sarukhanyan, Edita; Breitinger, Ulrike; Villmann, Carmen; Banoub, Maha M; Breitinger, Hans-Georg; Dandekar, Thomas; Holzgrabe, Ulrike; Sotriffer, Christoph; Jensen, Anders A; Zlotos, Darius P

2016-12-23

A series of (E)-11-isonitrosostrychnine oxime ethers, 2-aminostrychnine, (strychnine-2-yl)propionamide, 18-oxostrychnine, and N-propylstrychnine bromide were synthesized and evaluated pharmacologically at human α1 and α1β glycine receptors in a functional fluorescence-based and a whole-cell patch-clamp assay and in [ 3 H]strychnine binding studies. 2-Aminostrychnine and the methyl, allyl, and propargyl oxime ethers were the most potent α1 and α1β antagonists in the series, displaying IC 50 values similar to those of strychnine at the two receptors. Docking experiments to the strychnine binding site of the crystal structure of the α3 glycine receptor indicated the same orientation of the strychnine core for all analogues. For the most potent oxime ethers, the ether substituent was accommodated in a lipophilic receptor binding pocket. The findings identify the oxime hydroxy group as a suitable attachment point for linking two strychnine pharmacophores by a polymethylene spacer and are, therefore, important for the design of bivalent ligands targeting glycine receptors.

Glycine receptor mechanism elucidated by electron cryo-microscopy.

PubMed

Du, Juan; Lü, Wei; Wu, Shenping; Cheng, Yifan; Gouaux, Eric

2015-10-08

The strychnine-sensitive glycine receptor (GlyR) mediates inhibitory synaptic transmission in the spinal cord and brainstem and is linked to neurological disorders, including autism and hyperekplexia. Understanding of molecular mechanisms and pharmacology of glycine receptors has been hindered by a lack of high-resolution structures. Here we report electron cryo-microscopy structures of the zebrafish α1 GlyR with strychnine, glycine, or glycine and ivermectin (glycine/ivermectin). Strychnine arrests the receptor in an antagonist-bound closed ion channel state, glycine stabilizes the receptor in an agonist-bound open channel state, and the glycine/ivermectin complex adopts a potentially desensitized or partially open state. Relative to the glycine-bound state, strychnine expands the agonist-binding pocket via outward movement of the C loop, promotes rearrangement of the extracellular and transmembrane domain 'wrist' interface, and leads to rotation of the transmembrane domain towards the pore axis, occluding the ion conduction pathway. These structures illuminate the GlyR mechanism and define a rubric to interpret structures of Cys-loop receptors.

Gab-family adapter molecules in signal transduction of cytokine and growth factor receptors, and T and B cell antigen receptors.

PubMed

Hibi, M; Hirano, T

2000-04-01

Gab1 and Gab2 (Grb2 associated binder 1 and 2) are scaffolding adapter molecules that display sequence similarity with Drosophila DOS (daughter of sevenless), which is a potential substrate for the protein tyrosine phosphatase, Corkscrew, Both Gab1 and Gab2, like DOS, have a pleckstrin homology domain and potential binding sites for SH2 and SH3 domains. Gab1 and Gab2 are phosphorylated on tyrosine upon the stimulation of various cytokines, growth factors, and antigen receptors, and interact with signaling molecules, such as Grb2, SHP-2, and PI-3 kinase. Overexpression of Gab1 or Gab2 mimics or enhances growth factor or cytokine-mediated biological processes and activates ERK MAP kinase. These data imply that Gab1 and Gab2 act downstream of a broad range of cytokine and growth factor receptors, as well as T and B antigen receptors, and link these receptors to ERK MAP kinase and biological actions.

CCR5 adopts three homodimeric conformations that control cell surface delivery.

PubMed

Jin, Jun; Momboisse, Fanny; Boncompain, Gaelle; Koensgen, Florian; Zhou, Zhicheng; Cordeiro, Nelia; Arenzana-Seisdedos, Fernando; Perez, Franck; Lagane, Bernard; Kellenberger, Esther; Brelot, Anne

2018-05-08

Biophysical methods and x-ray crystallography have revealed that class A G protein-coupled receptors (GPCRs) can form homodimers. We combined computational approaches with receptor cross-linking, energy transfer, and a newly developed functional export assay to characterize the residues involved in the dimerization interfaces of the chemokine receptor CCR5, the major co-receptor for HIV-1 entry into cells. We provide evidence of three distinct CCR5 dimeric organizations, involving residues of transmembrane helix 5. Two dimeric states corresponded to unliganded receptors, whereas the binding of the inverse agonist maraviroc stabilized a third state. We found that CCR5 dimerization was required for targeting the receptor to the plasma membrane. These data suggest that dimerization contributes to the conformational diversity of inactive class A GPCRs and may provide new opportunities to investigate the cellular entry of HIV-1 and mechanisms for its inhibition. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

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

NASA Astrophysics Data System (ADS)

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

2015-03-01

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

Tuning the allosteric regulation of artificial muscarinic and dopaminergic ligand-gated potassium channels by protein engineering of G protein-coupled receptors

PubMed Central

Moreau, Christophe J.; Revilloud, Jean; Caro, Lydia N.; Dupuis, Julien P.; Trouchet, Amandine; Estrada-Mondragón, Argel; Nieścierowicz, Katarzyna; Sapay, Nicolas; Crouzy, Serge; Vivaudou, Michel

2017-01-01

Ligand-gated ion channels enable intercellular transmission of action potential through synapses by transducing biochemical messengers into electrical signal. We designed artificial ligand-gated ion channels by coupling G protein-coupled receptors to the Kir6.2 potassium channel. These artificial channels called ion channel-coupled receptors offer complementary properties to natural channels by extending the repertoire of ligands to those recognized by the fused receptors, by generating more sustained signals and by conferring potassium selectivity. The first artificial channels based on the muscarinic M2 and the dopaminergic D2L receptors were opened and closed by acetylcholine and dopamine, respectively. We find here that this opposite regulation of the gating is linked to the length of the receptor C-termini, and that C-terminus engineering can precisely control the extent and direction of ligand gating. These findings establish the design rules to produce customized ligand-gated channels for synthetic biology applications. PMID:28145461

Targeting the fibroblast growth factor receptors for the treatment of cancer.

PubMed

Lemieux, Steven M; Hadden, M Kyle

2013-06-01

Receptor tyrosine kinases (RTKs) are transmembrane proteins that play a critical role in stimulating signal transduction cascades to influence cell proliferation, growth, and differentiation and they have also been shown to promote angiogenesis when they are up-regulated or mutated. For this reason, their dysfunction has been implicated in the development of human cancer. Over the past decade, much attention has been devoted to developing inhibitors and antibodies against several classes of RTKs, including vascular endothelial growth factor receptors (VEGFRs), epidermal growth factor receptors (EGFRs), and platelet-derived growth factor receptors (PDGFRs). More recently, interest in the fibroblast growth factor receptor (FGFR) class of RTKs as a drug target for the treatment of cancer has emerged. Signaling through FGFRs is critical for normal cellular function and their dysregulation has been linked to various malignancies such as breast and prostate cancer. This review will focus on the current state of both small molecules and antibodies as FGFR inhibitors to provide insight into their development and future potential as anti-cancer agents.

Endothelin-converting enzyme 1 degrades neuropeptides in endosomes to control receptor recycling.

PubMed

Roosterman, Dirk; Cottrell, Graeme S; Padilla, Benjamin E; Muller, Laurent; Eckman, Christopher B; Bunnett, Nigel W; Steinhoff, Martin

2007-07-10

Neuropeptide signaling requires the presence of G protein-coupled receptors (GPCRs) at the cell surface. Activated GPCRs interact with beta-arrestins, which mediate receptor desensitization, endocytosis, and mitogenic signaling, and the peptide-receptor-arrestin complex is sequestered into endosomes. Although dissociation of beta-arrestins is required for receptor recycling and resensitization, the critical event that initiates this process is unknown. Here we report that the agonist availability in the endosomes, controlled by the membrane metalloendopeptidase endothelin-converting enzyme 1 (ECE-1), determines stability of the peptide-receptor-arrestin complex and regulates receptor recycling and resensitization. Substance P (SP) binding to the tachykinin neurokinin 1 receptor (NK1R) induced membrane translocation of beta-arrestins followed by trafficking of the SP-NK1R-beta-arrestin complex to early endosomes containing ECE-1a-d. ECE-1 degraded SP in acidified endosomes, disrupting the complex; beta-arrestins returned to the cytosol, and the NK1R, freed from beta-arrestins, recycled and resensitized. An ECE-1 inhibitor, by preventing NK1R recycling in endothelial cells, inhibited resensitization of SP-induced inflammation. This mechanism is a general one because ECE-1 similarly regulated NK3R resensitization. Thus, peptide availability in endosomes, here regulated by ECE-1, determines the stability of the peptide-receptor-arrestin complex. This mechanism regulates receptor recycling, which is necessary for sustained signaling, and it may also control beta-arrestin-dependent mitogenic signaling of endocytosed receptors. We propose that other endosomal enzymes and transporters may similarly control the availability of transmitters in endosomes to regulate trafficking and signaling of GPCRs. Antagonism of these endosomal processes represents a strategy for inhibiting sustained signaling of receptors, and defects may explain the tachyphylaxis of drugs that are receptor agonists.

Delta-opioid receptors as targets for migraine therapy.

PubMed

Charles, Andrew; Pradhan, Amynah A

2016-06-01

The purpose of this review is to contrast the properties of the δ-opioid receptor with those of the μ-opioid receptor, which is the primary target of most currently available opioid analgesics. We also discuss preclinical evidence that indicates the potential efficacy of δ-opioid receptor agonists as migraine therapy. The use of currently available opioid analgesics is highly problematic for patients with migraine. Delta-opioid receptors have key differences from μ receptors; these differences make the δ receptor an attractive therapeutic target for migraine. Delta-opioid receptors are expressed in both the peripheral and central nervous system in anatomical regions and cell types that are believed to play a role in migraine. Delta-receptor agonists have also shown promising effects in multiple migraine models, including nitroglycerin evoked hyperalgesia and conditioned place aversion, and cortical spreading depression. Evidence from animal models indicates that activation of δ receptors is less likely to cause tolerance and dependence, and less likely to cause hyperalgesia. In addition, δ receptors may have antidepressant and anxiolytic properties that are distinct from those of μ receptors. In human studies investigating other conditions, δ-receptor agonists have been generally safe and well tolerated. Delta-opioid receptor agonists have promising potential as acute and/or preventive migraine therapies, without the problems associated with currently used opioid analgesics.

Functional properties of an isolated. cap alpha beta. heterodimeric human placenta insulin-like growth factor 1 receptor complex

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

Feltz, S.M.; Swanson, M.L.; Wemmie, J.A.

1988-05-03

Treatment of human placenta membranes at pH 8.5 in the presence of 2.0 mM dithiothreitol (DTT) for 5 min, followed by the simultaneous removal of the DTT and pH adjustment of pH 7.6, resulted in the formation of a functional ..cap alpha beta.. heterodimeric insulin-like growth factor 1 (IGF-1) receptor complex from the native ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric disulfide-linked state. The membrane-bound ..cap alpha beta.. heterodimeric complex displayed similar curvilinear /sup 125/I-IGF-1 equilibrium binding compared to the ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric complex. /sup 125/I-IGF-1 binding to both the isolated ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric and ..cap alpha beta..more » heterodimeric complexes demonstrated a marked straightening of the Scatchard plots, compared to the placenta membrane-bound IGF-1 receptors, with a 2-fold increase in the high-affinity binding component. IGF-1 stimulation of IGF-1 receptor autophosphorylation indicated that the ligand-dependent activation of ..cap alpha beta.. heterodimeric protein kinase activity occurred concomitant with the reassociation into a covalent ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric state. These data demonstrate that (i) a combination of alkaline pH and DTT treatment of human placenta membranes results in the formation of an ..cap alpha beta.. heterodimeric IGF-1 receptor complex, (ii) unlike the insulin receptor, high-affinity homogeneous IGF-1 binding occurs in both the ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric and ..cap alpha beta.. heterodimeric complexes, and (iii) IGF-1-dependent autophosphorylation of the ..cap alpha beta.. heterodimeric IGF-1 receptor complex correlates wit an IGF-1 dependent covalent reassociation into an ..cap alpha../sub 2/..beta../sub 2/ heterotetrameric disulfide-linked state.« less

Targeting allergen to FcgammaRI reveals a novel T(H)2 regulatory pathway linked to thymic stromal lymphopoietin receptor.

PubMed

Hulse, Kathryn E; Reefer, Amanda J; Engelhard, Victor H; Patrie, James T; Ziegler, Steven F; Chapman, Martin D; Woodfolk, Judith A

2010-01-01

The molecule H22-Fel d 1, which targets cat allergen to FcgammaRI on dendritic cells (DCs), has the potential to treat cat allergy because of its T-cell modulatory properties. We sought to investigate whether the T-cell response induced by H22-Fel d 1 is altered in the presence of the T(H)2-promoting cytokine thymic stromal lymphopoietin (TSLP). Studies were performed in subjects with cat allergy with and without atopic dermatitis. Monocyte-derived DCs were primed with H22-Fel d 1 in the presence or absence of TSLP, and the resulting T-cell cytokine repertoire was analyzed by flow cytometry. The capacity for H22-Fel d 1 to modulate TSLP receptor expression on DCs was examined by flow cytometry in the presence or absence of inhibitors of Fc receptor signaling molecules. Surprisingly, TSLP alone was a weak inducer of T(H)2 responses irrespective of atopic status; however, DCs coprimed with TSLP and H22-Fel d 1 selectively and synergistically amplified T(H)2 responses in highly atopic subjects. This effect was OX40 ligand independent, pointing to an unconventional TSLP-mediated pathway. Expression of TSLP receptor was upregulated on atopic DCs primed with H22-Fel d 1 through a pathway regulated by FcgammaRI-associated signaling components, including src-related tyrosine kinases and Syk, as well as the downstream molecule phosphoinositide 3-kinase. Inhibition of TSLP receptor upregulation triggered by H22-Fel d 1 blocked TSLP-mediated T(H)2 responses. Discovery of a novel T(H)2 regulatory pathway linking FcgammaRI signaling to TSLP receptor upregulation and consequent TSLP-mediated effects questions the validity of receptor-targeted allergen vaccines. Copyright 2010 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

Pharmacology and Toxicology of N-Benzylphenethylamine ("NBOMe") Hallucinogens.

PubMed

Halberstadt, Adam L

2017-01-01

Serotonergic hallucinogens induce profound changes in perception and cognition. The characteristic effects of hallucinogens are mediated by 5-HT 2A receptor activation. One class of hallucinogens are 2,5-dimethoxy-substituted phenethylamines, such as the so-called 2C-X compounds 2,5-dimethoxy-4-bromophenethylamine (2C-B) and 2,5-dimethoxy-4-iodophenethylamine (2C-I). Addition of an N-benzyl group to phenethylamine hallucinogens produces a marked increase in 5-HT 2A -binding affinity and hallucinogenic potency. N-benzylphenethylamines ("NBOMes") such as N-(2-methoxybenzyl)-2,5-dimethoxy-4-iodophenethylamine (25I-NBOMe) show subnanomolar affinity for the 5-HT 2A receptor and are reportedly highly potent in humans. Several NBOMEs have been available from online vendors since 2010, resulting in numerous cases of toxicity and multiple fatalities. This chapter reviews the structure-activity relationships, behavioral pharmacology, metabolism, and toxicity of members of the NBOMe hallucinogen class. Based on a review of 51 cases of NBOMe toxicity reported in the literature, it appears that rhabdomyolysis is a relatively common complication of severe NBOMe toxicity, an effect that may be linked to NBOMe-induced seizures, hyperthermia, and vasoconstriction.

Transient receptor potential ion channels in primary sensory neurons as targets for novel analgesics

PubMed Central

Sousa-Valente, J; Andreou, A P; Urban, L; Nagy, I

2014-01-01

The last decade has witnessed an explosion in novel findings relating to the molecules involved in mediating the sensation of pain in humans. Transient receptor potential (TRP) ion channels emerged as the greatest group of molecules involved in the transduction of various physical stimuli into neuronal signals in primary sensory neurons, as well as, in the development of pain. Here, we review the role of TRP ion channels in primary sensory neurons in the development of pain associated with peripheral pathologies and possible strategies to translate preclinical data into the development of effective new analgesics. Based on available evidence, we argue that nociception-related TRP channels on primary sensory neurons provide highly valuable targets for the development of novel analgesics and that, in order to reduce possible undesirable side effects, novel analgesics should prevent the translocation from the cytoplasm to the cell membrane and the sensitization of the channels rather than blocking the channel pore or binding sites for exogenous or endogenous activators. LINKED ARTICLES This article is part of a themed section on the pharmacology of TRP channels. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-10 PMID:24283624

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

Alimirah, Fatouma; Peng, Xinjian; Yuan, Liang

Heterodimerization and cross-talk between nuclear hormone receptors often occurs. For example, estrogen receptor alpha (ER{alpha}) physically binds to peroxisome proliferator-activated receptor gamma (PPAR{gamma}) and inhibits its transcriptional activity. The interaction between PPAR{gamma} and the vitamin D receptor (VDR) however, is unknown. Here, we elucidate the molecular mechanisms linking PPAR{gamma} and VDR signaling, and for the first time we show that PPAR{gamma} physically associates with VDR in human breast cancer cells. We found that overexpression of PPAR{gamma} decreased 1{alpha},25-dihydroxyvitamin D{sub 3} (1,25D{sub 3}) mediated transcriptional activity of the vitamin D target gene, CYP24A1, by 49% and the activity of VDRE-luc, amore » vitamin D responsive reporter, by 75% in T47D human breast cancer cells. Deletion mutation experiments illustrated that helices 1 and 4 of PPAR{gamma}'s hinge and ligand binding domains, respectively, governed this suppressive function. Additionally, abrogation of PPAR{gamma}'s AF2 domain attenuated its repressive action on 1,25D{sub 3} transactivation, indicating that this domain is integral in inhibiting VDR signaling. PPAR{gamma} was also found to compete with VDR for their binding partner retinoid X receptor alpha (RXR{alpha}). Overexpression of RXR{alpha} blocked PPAR{gamma}'s suppressive effect on 1,25D{sub 3} action, enhancing VDR signaling. In conclusion, these observations uncover molecular mechanisms connecting the PPAR{gamma} and VDR pathways. -- Highlights: PPAR{gamma}'s role on 1{alpha},25-dihydroxyvitamin D{sub 3} transcriptional activity is examined. Black-Right-Pointing-Pointer PPAR{gamma} physically binds to VDR and inhibits 1{alpha},25-dihydroxyvitamin D{sub 3} action. Black-Right-Pointing-Pointer PPAR{gamma}'s hinge and ligand binding domains are important for this inhibitory effect. Black-Right-Pointing-Pointer PPAR{gamma} competes with VDR for the availability of their binding partner, RXR{alpha}.« less

Genetics Home Reference: Laron syndrome

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

PubMed

Taupin, J L; Anderson, P

1994-12-01

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

GHSR-D2R heteromerization modulates dopamine signaling through an effect on G protein conformation.

PubMed

Damian, Marjorie; Pons, Véronique; Renault, Pedro; M'Kadmi, Céline; Delort, Bartholomé; Hartmann, Lucie; Kaya, Ali I; Louet, Maxime; Gagne, Didier; Ben Haj Salah, Khoubaib; Denoyelle, Séverine; Ferry, Gilles; Boutin, Jean A; Wagner, Renaud; Fehrentz, Jean-Alain; Martinez, Jean; Marie, Jacky; Floquet, Nicolas; Galès, Céline; Mary, Sophie; Hamm, Heidi E; Banères, Jean-Louis

2018-04-24

The growth hormone secretagogue receptor (GHSR) and dopamine receptor (D2R) have been shown to oligomerize in hypothalamic neurons with a significant effect on dopamine signaling, but the molecular processes underlying this effect are still obscure. We used here the purified GHSR and D2R to establish that these two receptors assemble in a lipid environment as a tetrameric complex composed of two each of the receptors. This complex further recruits G proteins to give rise to an assembly with only two G protein trimers bound to a receptor tetramer. We further demonstrate that receptor heteromerization directly impacts on dopamine-mediated Gi protein activation by modulating the conformation of its α-subunit. Indeed, association to the purified GHSR:D2R heteromer triggers a different active conformation of Gαi that is linked to a higher rate of GTP binding and a faster dissociation from the heteromeric receptor. This is an additional mechanism to expand the repertoire of GPCR signaling modulation that could have implications for the control of dopamine signaling in normal and physiopathological conditions.

Sodium taurocholate cotransporting polypeptide is a functional receptor for human hepatitis B and D virus

PubMed Central

Yan, Huan; Zhong, Guocai; Xu, Guangwei; He, Wenhui; Jing, Zhiyi; Gao, Zhenchao; Huang, Yi; Qi, Yonghe; Peng, Bo; Wang, Haimin; Fu, Liran; Song, Mei; Chen, Pan; Gao, Wenqing; Ren, Bijie; Sun, Yinyan; Cai, Tao; Feng, Xiaofeng; Sui, Jianhua; Li, Wenhui

2012-01-01

Human hepatitis B virus (HBV) infection and HBV-related diseases remain a major public health problem. Individuals coinfected with its satellite hepatitis D virus (HDV) have more severe disease. Cellular entry of both viruses is mediated by HBV envelope proteins. The pre-S1 domain of the large envelope protein is a key determinant for receptor(s) binding. However, the identity of the receptor(s) is unknown. Here, by using near zero distance photo-cross-linking and tandem affinity purification, we revealed that the receptor-binding region of pre-S1 specifically interacts with sodium taurocholate cotransporting polypeptide (NTCP), a multiple transmembrane transporter predominantly expressed in the liver. Silencing NTCP inhibited HBV and HDV infection, while exogenous NTCP expression rendered nonsusceptible hepatocarcinoma cells susceptible to these viral infections. Moreover, replacing amino acids 157–165 of nonfunctional monkey NTCP with the human counterpart conferred its ability in supporting both viral infections. Our results demonstrate that NTCP is a functional receptor for HBV and HDV. DOI: http://dx.doi.org/10.7554/eLife.00049.001 PMID:23150796

The Role of TAM Family Receptors in Immune Cell Function: Implications for Cancer Therapy.

PubMed

Paolino, Magdalena; Penninger, Josef M

2016-10-21

The TAM receptor protein tyrosine kinases-Tyro3, Axl, and Mer-are essential regulators of immune homeostasis. Guided by their cognate ligands Growth arrest-specific gene 6 (Gas6) and Protein S (Pros1), these receptors ensure the resolution of inflammation by dampening the activation of innate cells as well as by restoring tissue function through promotion of tissue repair and clearance of apoptotic cells. Their central role as negative immune regulators is highlighted by the fact that deregulation of TAM signaling has been linked to the pathogenesis of autoimmune, inflammatory, and infectious diseases. Importantly, TAM receptors have also been associated with cancer development and progression. In a cancer setting, TAM receptors have a dual regulatory role, controlling the initiation and progression of tumor development and, at the same time, the associated anti-tumor responses of diverse immune cells. Thus, modulation of TAM receptors has emerged as a potential novel strategy for cancer treatment. In this review, we discuss our current understanding of how TAM receptors control immunity, with a particular focus on the regulation of anti-tumor responses and its implications for cancer immunotherapy.

Modular Activating Receptors in Innate and Adaptive Immunity.

PubMed

Berry, Richard; Call, Matthew E

2017-03-14

Triggering of cell-mediated immunity is largely dependent on the recognition of foreign or abnormal molecules by a myriad of cell surface-bound receptors. Many activating immune receptors do not possess any intrinsic signaling capacity but instead form noncovalent complexes with one or more dimeric signaling modules that communicate with a common set of kinases to initiate intracellular information-transfer pathways. This modular architecture, where the ligand binding and signaling functions are detached from one another, is a common theme that is widely employed throughout the innate and adaptive arms of immune systems. The evolutionary advantages of this highly adaptable platform for molecular recognition are visible in the variety of ligand-receptor interactions that can be linked to common signaling pathways, the diversification of receptor modules in response to pathogen challenges, and the amplification of cellular responses through incorporation of multiple signaling motifs. Here we provide an overview of the major classes of modular activating immune receptors and outline the current state of knowledge regarding how these receptors assemble, recognize their ligands, and ultimately trigger intracellular signal transduction pathways that activate immune cell effector functions.

Placental expression of D6 decoy receptor in preeclampsia

PubMed Central

Cho, Geum Joon; Lee, Eun Sung; Jin, Hye Mi; Lee, Ji Hye; Kim, Yeun Sun; Seol, Hyun-Joo; Hong, Soon-Cheol; Kim, Hai-Joong

2015-01-01

Objective The purpose of this study was to investigate the expression of the D6 decoy receptor that can bind chemokines and target them for degradation, resulting in inhibition of inflammation in placentas from preeclamptic and normal pregnancies. Methods The current study was carried out in 35 pregnant women (23 patients with preeclampsia and 12 healthy, normotensive pregnant women) during the third trimester of pregnancy. The expressions of D6 decoy receptor in the placenta were determined with real time reverse transcriptase polymerase chain reaction and western blotting. Results The mRNA and protein of D6 decoy receptor were detected in all of placentas from preeclamptic and normal pregnancies. Placental D6 decoy receptor mRNA expression was significantly lower in patients with preeclampsia than in patients with normal pregnancies. Western blot analyses revealed decreased protein expression in cases of preeclampsia. Conclusion The expression of the D6 decoy receptor in preeclamptic placentas was significantly lower than in normal placentas. Further studies are needed to clarify the underlying mechanisms that link decreased expression of placental D6 decoy receptor and preeclampsia. PMID:26430656

Association of the membrane estrogen receptor, GPR30, with breast tumor metastasis and transactivation of the epidermal growth factor receptor.

PubMed

Filardo, Edward J; Quinn, Jeffrey A; Sabo, Edmond

2008-10-01

The epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases function as a common signaling conduit for membrane receptors that lack intrinsic enzymatic activity, such as G-protein coupled receptors and integrins. GPR30, an orphan member of the seven transmembrane receptor (7TMR) superfamily has been linked to specific estrogen binding, rapid estrogen-mediated activation of adenylyl cyclase and the release of membrane-tethered proHB-EGF. More recently, GPR30 expression in primary breast adenocarcinoma has been associated with pathological parameters commonly used to assess breast cancer progression, including the development of extramammary metastases. This newly appreciated mechanism of cross communication between estrogen and EGF is consistent with the observation that 7TMR-mediated transactivation of the EGFR is a recurrent signaling paradigm and may explain prior data reporting the EGF-like effects of estrogen. The molecular details surrounding GPR30-mediated release of proHB-EGF, the involvement of integrin beta1 as a signaling intermediary in estrogen-dependent EGFR action, and the possible implications of these data for breast cancer progression are discussed herein.

Brain-Targeted (Pro)Renin Receptor Knockdown attenuates Angiotensin II-Dependent Hypertension

PubMed Central

Li, Wencheng; Peng, Hua; Cao, Theresa; Sato, Ryosuke; McDaniels, Sarah. J.; Kobori, Hiroyuki; Navar, L. Gabriel; Feng, Yumei

2012-01-01

The (pro)renin receptor is a newly discovered member of the brain renin-angiotensin system. To investigate the role of brain (pro)renin receptor in hypertension, adeno-associated virus-mediated (pro)renin receptor shRNA was used to knockdown (pro)renin receptor expression in the brain of non-transgenic normotensive and human renin-angiotensinogen double transgenic hypertensive mice. Blood pressure was monitored using implanted telemetric probes in conscious animals. Real-time PCR and immunostaining were performed to determine (pro)renin receptor, angiotensin II type 1 receptor and vasopressin mRNA levels. Plasma vasopressin levels were determined by Enzyme-Linked Immuno Sorbent Assay. Double transgenic mice exhibited higher blood pressure, elevated cardiac and vascular sympathetic tone, and impaired spontaneous baroreflex sensitivity. Intracerebroventricular delivery of (pro)renin receptor shRNA significantly reduced blood pressure, cardiac and vasomotor sympathetic tone, and improved baroreflex sensitivity compared to the control virus treatment in double transgenic mice. (Pro)renin receptor knockdown significantly reduced angiotensin II type 1 receptor and vasopressin levels in double transgenic mice. These data indicate that (pro)renin receptor knockdown in the brain attenuates angiotensin II-dependent hypertension and is associated with a decrease insympathetic tone and an improvement of the baroreflex sensitivity. In addition, brain-targeted (pro)renin receptor knockdown is associated with down-regulation of angiotensin II type 1 receptor and vasopressin levels. We conclude that central (pro)renin receptor contributes to the pathogenesis of hypertension in human renin-angiotensinogen transgenic mice. PMID:22526255

Assembly of high-affinity insulin receptor agonists and antagonists from peptide building blocks

PubMed Central

Schäffer, Lauge; Brissette, Renee E.; Spetzler, Jane C.; Pillutla, Renuka C.; Østergaard, Søren; Lennick, Michael; Brandt, Jakob; Fletcher, Paul W.; Danielsen, Gillian M.; Hsiao, Ku-Chuan; Andersen, Asser S.; Dedova, Olga; Ribel, Ulla; Hoeg-Jensen, Thomas; Hansen, Per Hertz; Blume, Arthur J.; Markussen, Jan; Goldstein, Neil I.

2003-01-01

Insulin is thought to elicit its effects by crosslinking the two extracellular α-subunits of its receptor, thereby inducing a conformational change in the receptor, which activates the intracellular tyrosine kinase signaling cascade. Previously we identified a series of peptides binding to two discrete hotspots on the insulin receptor. Here we show that covalent linkage of such peptides into homodimers or heterodimers results in insulin agonists or antagonists, depending on how the peptides are linked. An optimized agonist has been shown, both in vitro and in vivo, to have a potency close to that of insulin itself. The ability to construct such peptide derivatives may offer a path for developing agonists or antagonists for treatment of a wide variety of diseases. PMID:12684539

Ionotropic GABA receptor antagonism-induced adverse outcome pathways for potential neurotoxicity biomarkers.

PubMed

Gong, Ping; Hong, Huixiao; Perkins, Edward J

2015-01-01

Antagonism of ionotropic GABA receptors (iGABARs) can occur at three distinct types of receptor binding sites causing chemically induced epileptic seizures. Here we review three adverse outcome pathways, each characterized by a specific molecular initiating event where an antagonist competitively binds to active sites, negatively modulates allosteric sites or noncompetitively blocks ion channel on the iGABAR. This leads to decreased chloride conductance, followed by depolarization of affected neurons, epilepsy-related death and ultimately decreased population. Supporting evidence for causal linkages from the molecular to population levels is presented and differential sensitivity to iGABAR antagonists in different GABA receptors and organisms discussed. Adverse outcome pathways are poised to become important tools for linking mechanism-based biomarkers to regulated outcomes in next-generation risk assessment.

Adenosine receptors regulate gap junction coupling of the human cerebral microvascular endothelial cells hCMEC/D3 by Ca2+ influx through cyclic nucleotide-gated channels.

PubMed

Bader, Almke; Bintig, Willem; Begandt, Daniela; Klett, Anne; Siller, Ina G; Gregor, Carola; Schaarschmidt, Frank; Weksler, Babette; Romero, Ignacio; Couraud, Pierre-Olivier; Hell, Stefan W; Ngezahayo, Anaclet

2017-04-15

Gap junction channels are essential for the formation and regulation of physiological units in tissues by allowing the lateral cell-to-cell diffusion of ions, metabolites and second messengers. Stimulation of the adenosine receptor subtype A 2B increases the gap junction coupling in the human blood-brain barrier endothelial cell line hCMEC/D3. Although the increased gap junction coupling is cAMP-dependent, neither the protein kinase A nor the exchange protein directly activated by cAMP were involved in this increase. We found that cAMP activates cyclic nucleotide-gated (CNG) channels and thereby induces a Ca 2+ influx, which leads to the increase in gap junction coupling. The report identifies CNG channels as a possible physiological link between adenosine receptors and the regulation of gap junction channels in endothelial cells of the blood-brain barrier. The human cerebral microvascular endothelial cell line hCMEC/D3 was used to characterize the physiological link between adenosine receptors and the gap junction coupling in endothelial cells of the blood-brain barrier. Expressed adenosine receptor subtypes and connexin (Cx) isoforms were identified by RT-PCR. Scrape loading/dye transfer was used to evaluate the impact of the A 2A and A 2B adenosine receptor subtype agonist 2-phenylaminoadenosine (2-PAA) on the gap junction coupling. We found that 2-PAA stimulated cAMP synthesis and enhanced gap junction coupling in a concentration-dependent manner. This enhancement was accompanied by an increase in gap junction plaques formed by Cx43. Inhibition of protein kinase A did not affect the 2-PAA-related enhancement of gap junction coupling. In contrast, the cyclic nucleotide-gated (CNG) channel inhibitor l-cis-diltiazem, as well as the chelation of intracellular Ca 2+ with BAPTA, or the absence of external Ca 2+ , suppressed the 2-PAA-related enhancement of gap junction coupling. Moreover, we observed a 2-PAA-dependent activation of CNG channels by a combination of electrophysiology and pharmacology. In conclusion, the stimulation of adenosine receptors in hCMEC/D3 cells induces a Ca 2+ influx by opening CNG channels in a cAMP-dependent manner. Ca 2+ in turn induces the formation of new gap junction plaques and a consecutive sustained enhancement of gap junction coupling. The report identifies CNG channels as a physiological link that integrates gap junction coupling into the adenosine receptor-dependent signalling of endothelial cells of the blood-brain barrier. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

In situ trans ligands of CD22 identified by glycan-protein photocross-linking-enabled proteomics.

PubMed

Ramya, T N C; Weerapana, Eranthie; Liao, Lujian; Zeng, Ying; Tateno, Hiroaki; Liao, Liang; Yates, John R; Cravatt, Benjamin F; Paulson, James C

2010-06-01

CD22, a regulator of B-cell signaling, is a siglec that recognizes the sequence NeuAcalpha2-6Gal on glycoprotein glycans as ligands. CD22 interactions with glycoproteins on the same cell (in cis) and apposing cells (in trans) modulate its activity in B-cell receptor signaling. Although CD22 predominantly recognizes neighboring CD22 molecules as cis ligands on B-cells, little is known about the trans ligands on apposing cells. We conducted a proteomics scale study to identify candidate trans ligands of CD22 on B-cells by UV photocross-linking CD22-Fc chimera bound to B-cell glycoproteins engineered to carry sialic acids with a 9-aryl azide moiety. Using mass spectrometry-based quantitative proteomics to analyze the cross-linked products, 27 glycoproteins were identified as candidate trans ligands. Next, CD22 expressed on the surface of one cell was photocross-linked to glycoproteins on apposing B-cells followed by immunochemical analysis of the products with antibodies to the candidate ligands. Of the many candidate ligands, only the B-cell receptor IgM was found to be a major in situ trans ligand of CD22 that is selectively redistributed to the site of cell contact upon interaction with CD22 on the apposing cell.

Calorimetric Studies of Bovine Rod Outer Segment Disk Membranes Support a Monomeric Unit for Both Rhodopsin and Opsin

PubMed Central

Edrington, Thomas C.; Bennett, Michael; Albert, Arlene D.

2008-01-01

The photoreceptor rhodopsin is a G-protein coupled receptor that has recently been proposed to exist as a dimer or higher order oligomer, in contrast to the previously described monomer, in retinal rod outer segment disk membranes. Rhodopsin exhibits considerably greater thermal stability than opsin (the bleached form of the receptor), which is reflected in an ∼15°C difference in the thermal denaturation temperatures (Tm) of rhodopsin and opsin as measured by differential scanning calorimetry. Here we use differential scanning calorimetry to investigate the effect of partial bleaching of disk membranes on the Tm of rhodopsin and of opsin in native disk membranes, as well as in cross-linked disk membranes in which rhodopsin dimers are known to be present. The Tms of rhodopsin and opsin are expected to be perturbed if mixed oligomers are present. The Tm remained constant for rhodopsin and opsin in native disks regardless of the level of bleaching. In contrast, the Tm of cross-linked rhodopsin in disk membranes was dependent on the extent of bleaching. The energy of activation for denaturation of rhodopsin and cross-linked rhodopsin was calculated. Cross-linking rhodopsin significantly decreased the energy of activation. We conclude that in native disk membranes, rhodopsin behaves predominantly as a monomer. PMID:18586850

Impact of antipsychotic medication on transcranial direct current stimulation (tDCS) effects in schizophrenia patients.

PubMed

Agarwal, Sri Mahavir; Bose, Anushree; Shivakumar, Venkataram; Narayanaswamy, Janardhanan C; Chhabra, Harleen; Kalmady, Sunil V; Varambally, Shivarama; Nitsche, Michael A; Venkatasubramanian, Ganesan; Gangadhar, Bangalore N

2016-01-30

Transcranial direct current stimulation (tDCS) has generated interest as a treatment modality for schizophrenia. Dopamine, a critical pathogenetic link in schizophrenia, is also known to influence tDCS effects. We evaluated the influence of antipsychotic drug type (as defined by dopamine D2 receptor affinity) on the impact of tDCS in schizophrenia. DSM-IV-TR-diagnosed schizophrenia patients [N=36] with persistent auditory hallucinations despite adequate antipsychotic treatment were administered add-on tDCS. Patients were divided into three groups based on the antipsychotic's affinity to D2 receptors. An auditory hallucinations score (AHS) was measured using the auditory hallucinations subscale of the Psychotic Symptom Rating Scales (PSYRATS). Add-on tDCS resulted in a significant reduction inAHS. Antipsychotic drug type had a significant effect on AHS reduction. Patients treated with high affinity antipsychotics showed significantly lesser improvement compared to patients on low affinity antipsychotics or a mixture of the two. Furthermore, a significant sex-by-group interaction occurred; type of medication had an impact on tDCS effects only in women. Improvement differences could be due to the larger availability of the dopamine receptor system in patients taking antipsychotics with low D2 affinity. Sex-specific differences suggest potential estrogen-mediated effects. This study reports a first-time observation on the clinical utility of antipsychotic drug type in predicting tDCS effects in schizophrenia. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Endogenous opioid system: a promising target for future smoking cessation medications.

PubMed

Norman, Haval; D'Souza, Manoranjan S

2017-05-01

Nicotine addiction continues to be a health challenge across the world. Despite several approved medications, smokers continue to relapse. Several human and animal studies have evaluated the role of the endogenous opioid system as a potential target for smoking cessation medications. In this review, studies that have elucidated the role of the mu (MORs), delta (DORs), and kappa (KORs) opioid receptors in nicotine reward, nicotine withdrawal, and reinstatement of nicotine seeking will be discussed. Additionally, the review will discuss discrepancies in the literature and therapeutic potential of the endogenous opioid system, and suggest studies to address gaps in knowledge with respect to the role of the opioid receptors in nicotine dependence. Data available till date suggest that blockade of the MORs and DORs decreased the rewarding effects of nicotine, while activation of the MORs and DORs decreased nicotine withdrawal-induced aversive effects. In contrast, activation of the KORs decreased the rewarding effects of nicotine, while blockade of the KORs decreased nicotine withdrawal-induced aversive effects. Interestingly, blockade of the MORs and KORs attenuated reinstatement of nicotine seeking. In humans, MOR antagonists have shown benefits in select subpopulations of smokers and further investigation is required to realize their full therapeutic potential. Future work must assess the influence of polymorphisms in opioid receptor-linked genes in nicotine dependence, which will help in both identifying individuals vulnerable to nicotine addiction and the development of opioid-based smoking cessation medications. Overall, the endogenous opioid system continues to be a promising target for future smoking cessation medications.

Protein kinase A is part of a mechanism that regulates nuclear reimport of the nuclear tRNA export receptors Los1p and Msn5p.

PubMed

Pierce, Jacqueline B; van der Merwe, George; Mangroo, Dev

2014-02-01

The two main signal transduction mechanisms that allow eukaryotes to sense and respond to changes in glucose availability in the environment are the cyclic AMP (cAMP)/protein kinase A (PKA) and AMP-activated protein kinase (AMPK)/Snf1 kinase-dependent pathways. Previous studies have shown that the nuclear tRNA export process is inhibited in Saccharomyces cerevisiae deprived of glucose. However, the signal transduction pathway involved and the mechanism by which glucose availability regulates nuclear-cytoplasmic tRNA trafficking are not understood. Here, we show that inhibition of nuclear tRNA export is caused by a block in nuclear reimport of the tRNA export receptors during glucose deprivation. Cytoplasmic accumulation of the tRNA export receptors during glucose deprivation is not caused by activation of Snf1p. Evidence obtained suggests that PKA is part of the mechanism that regulates nuclear reimport of the tRNA export receptors in response to glucose availability. This mechanism does not appear to involve phosphorylation of the nuclear tRNA export receptors by PKA. The block in nuclear reimport of the tRNA export receptors appears to be caused by activation of an unidentified mechanism when PKA is turned off during glucose deprivation. Taken together, the data suggest that PKA facilitates return of the tRNA export receptors to the nucleus by inhibiting an unidentified activity that facilitates cytoplasmic accumulation of the tRNA export receptors when glucose in the environment is limiting. A PKA-independent mechanism was also found to regulate nuclear tRNA export in response to glucose availability. This mechanism, however, does not regulate nuclear reimport of the tRNA export receptors.

Protein Kinase A Is Part of a Mechanism That Regulates Nuclear Reimport of the Nuclear tRNA Export Receptors Los1p and Msn5p

PubMed Central

Pierce, Jacqueline B.; van der Merwe, George

2014-01-01

The two main signal transduction mechanisms that allow eukaryotes to sense and respond to changes in glucose availability in the environment are the cyclic AMP (cAMP)/protein kinase A (PKA) and AMP-activated protein kinase (AMPK)/Snf1 kinase-dependent pathways. Previous studies have shown that the nuclear tRNA export process is inhibited in Saccharomyces cerevisiae deprived of glucose. However, the signal transduction pathway involved and the mechanism by which glucose availability regulates nuclear-cytoplasmic tRNA trafficking are not understood. Here, we show that inhibition of nuclear tRNA export is caused by a block in nuclear reimport of the tRNA export receptors during glucose deprivation. Cytoplasmic accumulation of the tRNA export receptors during glucose deprivation is not caused by activation of Snf1p. Evidence obtained suggests that PKA is part of the mechanism that regulates nuclear reimport of the tRNA export receptors in response to glucose availability. This mechanism does not appear to involve phosphorylation of the nuclear tRNA export receptors by PKA. The block in nuclear reimport of the tRNA export receptors appears to be caused by activation of an unidentified mechanism when PKA is turned off during glucose deprivation. Taken together, the data suggest that PKA facilitates return of the tRNA export receptors to the nucleus by inhibiting an unidentified activity that facilitates cytoplasmic accumulation of the tRNA export receptors when glucose in the environment is limiting. A PKA-independent mechanism was also found to regulate nuclear tRNA export in response to glucose availability. This mechanism, however, does not regulate nuclear reimport of the tRNA export receptors. PMID:24297441

S2RSLDB: a comprehensive manually curated, internet-accessible database of the sigma-2 receptor selective ligands.

PubMed

Nastasi, Giovanni; Miceli, Carla; Pittalà, Valeria; Modica, Maria N; Prezzavento, Orazio; Romeo, Giuseppe; Rescifina, Antonio; Marrazzo, Agostino; Amata, Emanuele

2017-01-01

Sigma (σ) receptors are accepted as a particular receptor class consisting of two subtypes: sigma-1 (σ 1 ) and sigma-2 (σ 2 ). The two receptor subtypes have specific drug actions, pharmacological profiles and molecular characteristics. The σ 2 receptor is overexpressed in several tumor cell lines, and its ligands are currently under investigation for their role in tumor diagnosis and treatment. The σ 2 receptor structure has not been disclosed, and researchers rely on σ 2 receptor radioligand binding assay to understand the receptor's pharmacological behavior and design new lead compounds. Here we present the sigma-2 Receptor Selective Ligands Database (S2RSLDB) a manually curated database of the σ 2 receptor selective ligands containing more than 650 compounds. The database is built with chemical structure information, radioligand binding affinity data, computed physicochemical properties, and experimental radioligand binding procedures. The S2RSLDB is freely available online without account login and having a powerful search engine the user may build complex queries, sort tabulated results, generate color coded 2D and 3D graphs and download the data for additional screening. The collection here reported is extremely useful for the development of new ligands endowed of σ 2 receptor affinity, selectivity, and appropriate physicochemical properties. The database will be updated yearly and in the near future, an online submission form will be available to help with keeping the database widely spread in the research community and continually updated. The database is available at http://www.researchdsf.unict.it/S2RSLDB.

Baclofen effects on alcohol seeking, self-administration and extinction of seeking responses in a within-session design in baboons

PubMed Central

Duke, Angela N.; Kaminski, Barbara J.; Weerts, Elise M.

2012-01-01

Baclofen, a GABAB receptor agonist, is currently under investigation as a potential treatment to prevent relapse to drinking in alcohol dependent persons. In the current study, two groups of baboons were trained under a chained schedule of reinforcement (CSR), with 3 linked components, which were each correlated with different response requirements and cues. Fulfilling the requirement in the 2nd link initiated the 3rd link where either alcohol (n=4) or a preferred non-alcoholic beverage (Tang, n=5) was available for self-administration; failure to complete the response requirement in Link 2 ended the session (no access to alcohol or Tang). Seeking responses in Link 2 were used as indices of the motivational processes thought to be involved in relapse. The effects of baclofen (0.1 – 2.4 mg/kg) were examined under conditions with alcohol or Tang access and under extinction. Under the CSR baclofen (1.8 and 2.4 mg/kg) significantly decreased (p<0.05) alcohol self-administration responses and total g/kg alcohol intake. In contrast, only the highest dose of baclofen (2.4 mg/kg) reduced Tang self-administration and consumption. Under within-session extinction conditions, baclofen (1.8 and 2.4 mg/kg) facilitated extinction of responding for both alcohol and Tang, particularly during the first 10 min of extinction. Baclofen may be effective in reducing craving and alcohol drinking, although the facilitation of extinction and suppression of both alcohol and Tang self-administration by baclofen suggests these effects may be related to a more general suppression of consummatory and conditioned behaviors. PMID:22458648

Baclofen effects on alcohol seeking, self-administration and extinction of seeking responses in a within-session design in baboons.

PubMed

Duke, Angela N; Kaminski, Barbara J; Weerts, Elise M

2014-01-01

Baclofen, a gamma-aminobutyric acidB receptor agonist, is currently under investigation as a potential treatment to prevent relapse to drinking in alcohol-dependent persons. In the current study, two groups of baboons were trained under a chained schedule of reinforcement (CSR), with three linked components, which were each correlated with different response requirements and cues. Fulfilling the requirement in the second link initiated the third link where either alcohol (n = 4) or a preferred non-alcoholic beverage (Tang, n = 5) was available for self-administration; failure to complete the response requirement in Link 2 ended the session (no access to alcohol or Tang). Seeking responses in Link 2 were used as indices of the motivational processes thought to be involved in relapse. The effects of baclofen (0.1-2.4 mg/kg) were examined under conditions with alcohol or Tang access and under extinction. Under the CSR, baclofen (1.8 and 2.4 mg/kg) significantly decreased (P < 0.05) alcohol self-administration responses and total g/kg alcohol intake. In contrast, only the highest dose of baclofen (2.4 mg/kg) reduced Tang self-administration and consumption. Under within-session extinction conditions, baclofen (1.8 and 2.4 mg/kg) facilitated extinction of responding for both alcohol and Tang, particularly during the first 10 minutes of extinction. Baclofen may be effective in reducing craving and alcohol drinking, although the facilitation of extinction and suppression of both alcohol and Tang self-administration by baclofen suggests these effects may be related to a more general suppression of consummatory and conditioned behaviors. © 2012 The Authors, Addiction Biology © 2012 Society for the Study of Addiction.

Regulation of B cell functions by the sialic acid-binding receptors siglec-G and CD22.

PubMed

Jellusova, Julia; Nitschke, Lars

2011-01-01

B cell antigen receptor (BCR) engagement can lead to many different physiologic outcomes. To achieve an appropriate response, the BCR signal is interpreted in the context of other stimuli and several additional receptors on the B cell surface participate in the modulation of the signal. Two members of the Siglec (sialic acid-binding immunoglobulin-like lectin) family, CD22 and Siglec-G have been shown to inhibit the BCR signal. Recent findings indicate that the ability of these two receptors to bind sialic acids might be important to induce tolerance to self-antigens. Sialylated glycans are usually absent on microbes but abundant in higher vertebrates and might therefore provide an important tolerogenic signal. Since the expression of the specific ligands for Siglec-G and CD22 is tightly regulated and since Siglecs are not only able to bind their ligands in trans but also on the same cell surface this might provide additional mechanisms to control the BCR signal. Although both Siglec-G and CD22 are expressed on B cells and are able to inhibit BCR mediated signaling, they also show unique biological functions. While CD22 is the dominant regulator of calcium signaling on conventional B2 cells and also seems to play a role on marginal zone B cells, Siglec-G exerts its function mainly on B1 cells and influences their lifespan and antibody production. Both Siglec-G and CD22 have also recently been linked to toll-like receptor signaling and may provide a link in the regulation of the adaptive and innate immune response of B cells.

A selective EP4 PGE2 receptor agonist alleviates disease in a new mouse model of X-linked nephrogenic diabetes insipidus

PubMed Central

Li, Jian Hua; Chou, Chung-Lin; Li, Bo; Gavrilova, Oksana; Eisner, Christoph; Schnermann, Jürgen; Anderson, Stasia A.; Deng, Chu-Xia; Knepper, Mark A.; Wess, Jürgen

2009-01-01

X-linked nephrogenic diabetes insipidus (XNDI) is a severe kidney disease caused by inactivating mutations in the V2 vasopressin receptor (V2R) gene that result in the loss of renal urine-concentrating ability. At present, no specific pharmacological therapy has been developed for XNDI, primarily due to the lack of suitable animal models. To develop what we believe to be the first viable animal model of XNDI, we generated mice in which the V2R gene could be conditionally deleted during adulthood by administration of 4-OH-tamoxifen. Radioligand-binding studies confirmed the lack of V2R-binding sites in kidneys following 4-OH-tamoxifen treatment, and further analysis indicated that upon V2R deletion, adult mice displayed all characteristic symptoms of XNDI, including polyuria, polydipsia, and resistance to the antidiuretic actions of vasopressin. Gene expression analysis suggested that activation of renal EP4 PGE2 receptors might compensate for the lack of renal V2R activity in XNDI mice. Strikingly, both acute and chronic treatment of the mutant mice with a selective EP4 receptor agonist greatly reduced all major manifestations of XNDI, including changes in renal morphology. These physiological improvements were most likely due to a direct action on EP4 receptors expressed on collecting duct cells. These findings illustrate the usefulness of the newly generated V2R mutant mice for elucidating and testing new strategies for the potential treatment of humans with XNDI. PMID:19729836

Mapping the signal peptide binding and oligomer contact sites of the core subunit of the pea twin arginine protein translocase.

PubMed

Ma, Xianyue; Cline, Kenneth

2013-03-01

Twin arginine translocation (Tat) systems of thylakoid and bacterial membranes transport folded proteins using the proton gradient as the sole energy source. Tat substrates have hydrophobic signal peptides with an essential twin arginine (RR) recognition motif. The multispanning cpTatC plays a central role in Tat operation: It binds the signal peptide, directs translocase assembly, and may facilitate translocation. An in vitro assay with pea (Pisum sativum) chloroplasts was developed to conduct mutagenesis and analysis of cpTatC functions. Ala scanning mutagenesis identified mutants defective in substrate binding and receptor complex assembly. Mutations in the N terminus (S1) and first stromal loop (S2) caused specific defects in signal peptide recognition. Cys matching between substrate and imported cpTatC confirmed that S1 and S2 directly and specifically bind the RR proximal region of the signal peptide. Mutations in four lumen-proximal regions of cpTatC were defective in receptor complex assembly. Copurification and Cys matching analyses suggest that several of the lumen proximal regions may be important for cpTatC-cpTatC interactions. Surprisingly, RR binding domains of adjacent cpTatCs directed strong cpTatC-cpTatC cross-linking. This suggests clustering of binding sites on the multivalent receptor complex and explains the ability of Tat to transport cross-linked multimers. Transport of substrate proteins cross-linked to the signal peptide binding site tentatively identified mutants impaired in the translocation step.

Bid Promotes K63-Linked Polyubiquitination of Tumor Necrosis Factor Receptor Associated Factor 6 (TRAF6) and Sensitizes to Mutant SOD1-Induced Proinflammatory Signaling in Microglia.

PubMed

Kinsella, Sinéad; König, Hans-Georg; Prehn, Jochen H M

2016-01-01

Mutations in the superoxide dismutase 1 (SOD1) gene contribute to motoneuron degeneration and are evident in 20% of familial amyotrophic lateral sclerosis cases. Mutant SOD1 induces microglial activation through a stimulation of Toll-like receptors 2 and 4 (TLR2 and TLR4). In the present study, we identified the proapoptotic Bcl-2 family protein Bid as a positive regulator of mutant SOD1-induced TLR-nuclear factor-κB (NF-κB) signaling in microglia. bid-deficient primary mouse microglia showed reduced NF-κB signaling in response to TLR4 activation or exposure to conditioned medium derived from SOD1 (G93A) expressing NSC-34 cells. Attenuation of NF-κB signaling in bid-deficient microglia was associated with lower levels of phosphorylated IKKα/β and p65, with a delayed degradation of IκBα and enhanced degradation of Peli1. Upstream of IKK, we found that Bid interacted with, and promoted, the K63-linked polyubiquitination of the E3 ubiquitin ligase tumor necrosis factor receptor associated factor 6 (TRAF6) in microglia. Our study suggests a key role for Bid in the regulation of TLR4-NF-κB proinflammatory signaling during mutant SOD1-induced disease pathology. Bid promotes TLR4-NF-κB signaling by interacting with TRAF6 and promoting TRAF6 K63-linked polyubiquitination in microglia.

Bid Promotes K63-Linked Polyubiquitination of Tumor Necrosis Factor Receptor Associated Factor 6 (TRAF6) and Sensitizes to Mutant SOD1-Induced Proinflammatory Signaling in Microglia123

PubMed Central

Kinsella, Sinéad

2016-01-01

Mutations in the superoxide dismutase 1 (SOD1) gene contribute to motoneuron degeneration and are evident in 20% of familial amyotrophic lateral sclerosis cases. Mutant SOD1 induces microglial activation through a stimulation of Toll-like receptors 2 and 4 (TLR2 and TLR4). In the present study, we identified the proapoptotic Bcl-2 family protein Bid as a positive regulator of mutant SOD1-induced TLR-nuclear factor-κB (NF-κB) signaling in microglia. bid-deficient primary mouse microglia showed reduced NF-κB signaling in response to TLR4 activation or exposure to conditioned medium derived from SOD1 G93A expressing NSC-34 cells. Attenuation of NF-κB signaling in bid-deficient microglia was associated with lower levels of phosphorylated IKKα/β and p65, with a delayed degradation of IκBα and enhanced degradation of Peli1. Upstream of IKK, we found that Bid interacted with, and promoted, the K63-linked polyubiquitination of the E3 ubiquitin ligase tumor necrosis factor receptor associated factor 6 (TRAF6) in microglia. Our study suggests a key role for Bid in the regulation of TLR4-NF-κB proinflammatory signaling during mutant SOD1-induced disease pathology. Bid promotes TLR4-NF-κB signaling by interacting with TRAF6 and promoting TRAF6 K63-linked polyubiquitination in microglia. PMID:27257617

Immune Suppression and Inflammation in the Progression of Breast Cancer

DTIC Science & Technology

2008-03-01

CD14 association with complement receptor type 3, which is reversed by neutrophil adhesion. J Immunol 1996;156:430-3. 27. Karin M, Greten FR. NF...52. Greten FR, Eckmann L, Greten TF, et al. IKKbeta links inflammation and tumorigenesis in a mouse model of colitis-associated cancer. Cell...ceramide docking to CD14 provokes ligand-specific receptor clustering in rafts. Eur J Immunol 2001;31:3153-64. 26. Karin M, Greten FR. NF-kappaB

Gut microbiota regulates maturation of the adult enteric nervous system via enteric serotonin networks.

PubMed

De Vadder, Filipe; Grasset, Estelle; Mannerås Holm, Louise; Karsenty, Gérard; Macpherson, Andrew J; Olofsson, Louise E; Bäckhed, Fredrik

2018-06-19

The enteric nervous system (ENS) is crucial for essential gastrointestinal physiologic functions such as motility, fluid secretion, and blood flow. The gut is colonized by trillions of bacteria that regulate host production of several signaling molecules including serotonin (5-HT) and other hormones and neurotransmitters. Approximately 90% of 5-HT originates from the intestine, and activation of the 5-HT 4 receptor in the ENS has been linked to adult neurogenesis and neuroprotection. Here, we tested the hypothesis that the gut microbiota could induce maturation of the adult ENS through release of 5-HT and activation of 5-HT 4 receptors. Colonization of germ-free mice with a microbiota from conventionally raised mice modified the neuroanatomy of the ENS and increased intestinal transit rates, which was associated with neuronal and mucosal 5-HT production and the proliferation of enteric neuronal progenitors in the adult intestine. Pharmacological modulation of the 5-HT 4 receptor, as well as depletion of endogenous 5-HT, identified a mechanistic link between the gut microbiota and maturation of the adult ENS through the release of 5-HT and activation of the 5-HT 4 receptor. Taken together, these findings show that the microbiota modulates the anatomy of the adult ENS in a 5-HT-dependent fashion with concomitant changes in intestinal transit. Copyright © 2018 the Author(s). Published by PNAS.

Identification of a new adapter protein that may link the common beta subunit of the receptor for granulocyte/macrophage colony-stimulating factor, interleukin (IL)-3, and IL-5 to phosphatidylinositol 3-kinase.

PubMed

Jücker, M; Feldman, R A

1995-11-17

Binding of human granulocyte/macrophage colony-stimulating factor (hGM-CSF) to its receptor induces the rapid activation of phosphatidylinositol-3 kinase (PI 3-kinase). As hGM-CSF receptor (hGMR) does not contain a consensus sequence for binding of PI 3-kinase, hGMR must use a distinct mechanism for its association with and activation of PI 3-kinase. Here, we describe the identification of a tyrosine-phosphorylated protein of 76-85 kDa (p80) that associates with the common beta subunit of hGMR and with the SH2 domains of the p85 subunit of PI 3-kinase in hGM-CSF-stimulated cells. Src/Yes and Lyn were tightly associated with the p80.PI 3-kinase complex, suggesting that p80 and other phosphotyrosyl proteins present in the complex were phosphorylated by Src family kinases. Tyrosine phosphorylation of p80 was only detected in hGM-CSF or human interleukin-3-stimulated cells, suggesting that activation of p80 might be specific for signaling via the common beta subunit. We postulate that p80 functions as an adapter protein that may participate in linking the hGM-CSF receptor to the PI 3-kinase signaling pathway.

Gender Interacts with Opioid Receptor Polymorphism A118G and Serotonin Receptor Polymorphism -1438 A/G on Speed-Dating Success.

PubMed

Wu, Karen; Chen, Chuansheng; Moyzis, Robert K; Greenberger, Ellen; Yu, Zhaoxia

2016-09-01

We examined an understudied but potentially important source of romantic attraction-genetics-using a speed-dating paradigm. The mu opioid receptor (OPRM1) polymorphism A118G (rs1799971) and the serotonin receptor (HTR2A) polymorphism -1438 A/G (rs6311) were studied because they have been implicated in social affiliation. Guided by the social role theory of mate selection and prior genetic evidence, we examined these polymorphisms' gender-specific associations with speed-dating success (i.e., date offers, mate desirability). A total of 262 single Asian Americans went on speed-dates with members of the opposite gender and completed interaction questionnaires about their partners. Consistent with our prediction, significant gender-by-genotype interactions were found for speed-dating success. Specifically, the minor variant of A118G (G-allele), which has been linked to submissiveness/social sensitivity, predicted greater speed-dating success for women, whereas the minor variant of -1438 A/G (G-allele), which has been linked to leadership/social dominance, predicted greater speed-dating success for men. For both polymorphisms, reverse "dampening" effects of minor variants were found for opposite-gender counterparts. These results support previous research on the importance of the opioid and serotonergic systems in social affiliation, indicating that their influence extends to dating success, with opposite, yet gender-norm consistent, effects for men and women.

Oxytocin and vasopressin: linking pituitary neuropeptides and their receptors to social neurocircuits

PubMed Central

Baribeau, Danielle A.; Anagnostou, Evdokia

2015-01-01

Oxytocin and vasopressin are pituitary neuropeptides that have been shown to affect social processes in mammals. There is growing interest in these molecules and their receptors as potential precipitants of, and/or treatments for, social deficits in neurodevelopmental disorders, including autism spectrum disorder. Numerous behavioral-genetic studies suggest that there is an association between these peptides and individual social abilities; however, an explanatory model that links hormonal activity at the receptor level to complex human behavior remains elusive. The following review summarizes the known associations between the oxytocin and vasopressin neuropeptide systems and social neurocircuits in the brain. Following a micro- to macro- level trajectory, current literature on the synthesis and secretion of these peptides, and the structure, function and distribution of their respective receptors is first surveyed. Next, current models regarding the mechanism of action of these peptides on microcircuitry and other neurotransmitter systems are discussed. Functional neuroimaging evidence on the acute effects of exogenous administration of these peptides on brain activity is then reviewed. Overall, a model in which the local neuromodulatory effects of pituitary neuropeptides on brainstem and basal forebrain regions strengthen signaling within social neurocircuits proves appealing. However, these findings are derived from animal models; more research is needed to clarify the relevance of these mechanisms to human behavior and treatment of social deficits in neuropsychiatric disorders. PMID:26441508

Oxytocin and vasopressin: linking pituitary neuropeptides and their receptors to social neurocircuits.

PubMed

Baribeau, Danielle A; Anagnostou, Evdokia

2015-01-01

Oxytocin and vasopressin are pituitary neuropeptides that have been shown to affect social processes in mammals. There is growing interest in these molecules and their receptors as potential precipitants of, and/or treatments for, social deficits in neurodevelopmental disorders, including autism spectrum disorder. Numerous behavioral-genetic studies suggest that there is an association between these peptides and individual social abilities; however, an explanatory model that links hormonal activity at the receptor level to complex human behavior remains elusive. The following review summarizes the known associations between the oxytocin and vasopressin neuropeptide systems and social neurocircuits in the brain. Following a micro- to macro- level trajectory, current literature on the synthesis and secretion of these peptides, and the structure, function and distribution of their respective receptors is first surveyed. Next, current models regarding the mechanism of action of these peptides on microcircuitry and other neurotransmitter systems are discussed. Functional neuroimaging evidence on the acute effects of exogenous administration of these peptides on brain activity is then reviewed. Overall, a model in which the local neuromodulatory effects of pituitary neuropeptides on brainstem and basal forebrain regions strengthen signaling within social neurocircuits proves appealing. However, these findings are derived from animal models; more research is needed to clarify the relevance of these mechanisms to human behavior and treatment of social deficits in neuropsychiatric disorders.

Co-evolution with chicken class I genes.

PubMed

Kaufman, Jim

2015-09-01

The concept of co-evolution (or co-adaptation) has a long history, but application at molecular levels (e.g., 'supergenes' in genetics) is more recent, with a consensus definition still developing. One interesting example is the chicken major histocompatibility complex (MHC). In contrast to typical mammals that have many class I and class I-like genes, only two classical class I genes, two CD1 genes and some non-classical Rfp-Y genes are known in chicken, and all are found on the microchromosome that bears the MHC. Rarity of recombination between the closely linked and polymorphic genes encoding classical class I and TAPs allows co-evolution, leading to a single dominantly expressed class I molecule in each MHC haplotype, with strong functional consequences in terms of resistance to infectious pathogens. Chicken tapasin is highly polymorphic, but co-evolution with TAP and class I genes remains unclear. T-cell receptors, natural killer (NK) cell receptors, and CD8 co-receptor genes are found on non-MHC chromosomes, with some evidence for co-evolution of surface residues and number of genes along the avian and mammalian lineages. Over even longer periods, co-evolution has been invoked to explain how the adaptive immune system of jawed vertebrates arose from closely linked receptor, ligand, and antigen-processing genes in the primordial MHC. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Multiple receptors coupled to phospholipase C gate long-term depression in visual cortex.

PubMed

Choi, Se-Young; Chang, Jeff; Jiang, Bin; Seol, Geun-Hee; Min, Sun-Seek; Han, Jung-Soo; Shin, Hee-Sup; Gallagher, Michela; Kirkwood, Alfredo

2005-12-07

Long-term depression (LTD) in sensory cortices depends on the activation of NMDA receptors. Here, we report that in visual cortical slices, the induction of LTD (but not long-term potentiation) also requires the activation of receptors coupled to the phospholipase C (PLC) pathway. Using immunolesions in combination with agonists and antagonists, we selectively manipulated the activation of alpha1 adrenergic, M1 muscarinic, and mGluR5 glutamatergic receptors. Inactivation of these PLC-coupled receptors prevents the induction of LTD, but only when the three receptors were inactivated together. LTD is fully restored by activating any one of them or by supplying intracellular D-myo-inositol-1,4,5-triphosphate (IP3). LTD was also impaired by intracellular application of PLC or IP3 receptor blockers, and it was absent in mice lacking PLCbeta1, the predominant PLC isoform in the forebrain. We propose that visual cortical LTD requires a minimum of PLC activity that can be supplied independently by at least three neurotransmitter systems. This essential requirement places PLC-linked receptors in a unique position to control the induction of LTD and provides a mechanism for gating visual cortical plasticity via extra-retinal inputs in the intact organism.

Purification and characterization of lutropin receptor from membranes of pig follicular fluid

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

Yarney, T.A.; Sairam, M.R.; Bhargavi, G.N.

1990-04-10

Membranes derived from free floating granulosa cells in porcine ovarian follicular fluid were used as a starting material for structural characterization of both LH/hCG and FSH receptors. The receptors were highly hormone-specific and showed single classes of high-affinity binding sites. Their molecular weights as determined by affinity cross-linking with their respective {sup 125}I-ligands were similarly 70,000. The membrane-localized receptors could be solubilized with reduced Triton X-100 in the presence of 20% glycerol with good retention of hormone binding activity. The purified receptor exhibited a high specificity for hCG and hLH but not for hFSH bTSH. The purified receptor was iodinatedmore » and visualized to be composed of a major protein of M{sub r} 70,000 and other minor proteins of molecular weights ranging from 14,000 to 40,000. Except for the M{sub r} 14,000 protein, all other protein species bound to the concanavalin A-Sepharose column. The data suggest that the ovarian LH/hCG and FSH receptors are structurally similar and consist of a single polypeptide chain, as recently documented for the LH/hCG receptor.« less

An Arg for Gly substitution at position 31 in the insulin receptor, linked to insulin resistance, inhibits receptor processing and transport.

PubMed

van der Vorm, E R; van der Zon, G C; Möller, W; Krans, H M; Lindhout, D; Maassen, J A

1992-01-05

In a patient with Leprechaunism, we have characterized a new mutation in the insulin receptor substituting Arg for Gly at position 31. The proband, the mother, and the maternal grandfather were heterozygous for the mutation. Fibroblasts of the proband show a strongly reduced number of high affinity insulin receptors on the cell surface, whereas fibroblasts of the healthy mother and grandfather show moderately reduced insulin receptor numbers. In the other family members neither the binding defect nor the Arg31 mutation was found. The Arg31-mutant receptor was overexpressed in Chinese hamster ovary cells. In these cells the mutant alpha beta-proreceptor was not proteolytically cleaved and no transport to the cell surface took place. The proreceptor was unable to bind insulin and to undergo autophosphorylation. In addition, the proreceptor was not recognized by monoclonal antibodies directed against conformation-dependent epitopes. These findings suggest that the Gly31 to Arg31 mutant is involved in the insulin receptor dysfunction seen in the Leprechaun patient. The mutation seems to alter the conformation of the receptor in such way that the transport of the proreceptor to the Golgi compartment, where proteolytical processing occurs, is inhibited.

Understanding Cytokine and Growth Factor Receptor Activation Mechanisms

PubMed Central

Atanasova, Mariya; Whitty, Adrian

2012-01-01

Our understanding of the detailed mechanism of action of cytokine and growth factor receptors – and particularly our quantitative understanding of the link between structure, mechanism and function – lags significantly behind our knowledge of comparable functional protein classes such as enzymes, G protein-coupled receptors, and ion channels. In particular, it remains controversial whether such receptors are activated by a mechanism of ligand-induced oligomerization, versus a mechanism in which the ligand binds to a pre-associated receptor dimer or oligomer that becomes activated through subsequent conformational rearrangement. A major limitation to progress has been the relative paucity of methods for performing quantitative mechanistic experiments on unmodified receptors expressed at endogenous levels on live cells. In this article we review the current state of knowledge on the activation mechanisms of cytokine and growth factor receptors, critically evaluate the evidence for and against the different proposed mechanisms, and highlight other key questions that remain unanswered. New approaches and techniques have led to rapid recent progress in this area, and the field is poised for major advances in the coming years, which promises to revolutionize our understanding of this large and biologically and medically important class of receptors. PMID:23046381

The anatomy of mammalian sweet taste receptors.

PubMed

Chéron, Jean-Baptiste; Golebiowski, Jérôme; Antonczak, Serge; Fiorucci, Sébastien

2017-02-01

All sweet-tasting compounds are detected by a single G-protein coupled receptor (GPCR), the heterodimer T1R2-T1R3, for which no experimental structure is available. The sweet taste receptor is a class C GPCR, and the recently published crystallographic structures of metabotropic glutamate receptor (mGluR) 1 and 5 provide a significant step forward for understanding structure-function relationships within this family. In this article, we recapitulate more than 600 single point site-directed mutations and available structural data to obtain a critical alignment of the sweet taste receptor sequences with respect to other class C GPCRs. Using this alignment, a homology 3D-model of the human sweet taste receptor is built and analyzed to dissect out the role of key residues involved in ligand binding and those responsible for receptor activation. Proteins 2017; 85:332-341. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

The Endocannabinoid System Modulating Levels of Consciousness, Emotions and Likely Dream Contents.

PubMed

Murillo-Rodriguez, Eric; Pastrana-Trejo, Jose Carlos; Salas-Crisóstomo, Mireille; de-la-Cruz, Miriel

2017-01-01

Cannabinoids are derivatives that are either compounds occurring naturally in the plant, Cannabis sativa or synthetic analogs of these molecules. The first and most widely investigated of the cannabinoids is Δ9-tetrahydrocannabinol (Δ9-THC), which is the main psychotropic constituent of cannabis and undergoes significant binding to cannabinoid receptors. These cannabinoid receptors are seven-transmembrane receptors that received their name from the fact that they respond to cannabinoid compounds, including Δ9-THC. The cannabinoid receptors have been described in rat, human and mouse brains and they have been named the CB1 and CB2 cannabinoid receptors. Later, an endogenous molecule that exerts pharmacological effects similar to those described by Δ9-THC and binds to the cannabinoid receptors was discovered. This molecule, named anandamide, was the first of five endogenous cannabinoid receptor agonists described to date in the mammalian brain and other tissues. Of these endogenous cannabinoids or endocannabinoids, the most thoroughly investigated to date have been anandamide and 2-arachidonoylglycerol (2-AG). Over the years, a significant number of articles have been published in the field of endogenous cannabinoids, suggesting a modulatory profile in multiple neurobiological roles of endocannabinoids. The general consensus accepts that the endogenous cannabinoid system includes natural ligands (such as anandamide and 2- AG), receptors (CB1 and CB2), and the main enzymes responsible for the hydrolysis of anandamide and 2-AG (fatty acid amide hydrolase [FAAH] and monoacylglycerol lipase [MAGL], respectively) as well as the anandamide membrane transporter (AMT). To date, diverse pieces of evidence have shown that the endocannabinoid system controls multiple functions such as feeding, pain, learning and memory and has been linked with various disturbances, such as Parkinson´s disease. Among the modulatory properties of the endocannabinoid system, current data indicate that the sleep-wake cycle is under the influence of endocannabinoids since the blocking of the CB1 cannabinoid receptor or the pharmacological inhibition of FAAH activity promotes wakefulness, whereas the obstruction of AMT function enhances sleep. However, no solid evidence is available regarding the role of the endocannabinoid system in an unquestionable emotional component of the sleep: Dream activity. Since dreaming is a mental activity that occurs during sleep (characterized by emotions, sensory perceptions, and bizarre components) and the endocannabinoid system modulates neurobiological processes involving consciousness, such as learning and memory, attention, pain perception, emotions and sleep, it is acceptable to hypothesize that the endocannabinoid system might be modulating dream activity. In this regard, an accumulative body of evidence in human and animal models has been reported regarding the role of the endocannabinoid system in the control of emotional states and dreams. Moreover, preliminary studies in humans have indicated that treatment with cannabinoids may decrease post-traumatic stress disorder symptoms, including nightmares. Thus, based on a review of the literature available in PubMed, this article hypothesizes a conceptual framework within which the endocannabinoid system might influence the generation of dream experiences. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Common Genetic Variation Near Melatonin Receptor 1A Gene Linked to Job-Related Exhaustion in Shift Workers

PubMed Central

Sulkava, Sonja; Ollila, Hanna M.; Alasaari, Jukka; Puttonen, Sampsa; Härmä, Mikko; Viitasalo, Katriina; Lahtinen, Alexandra; Lindström, Jaana; Toivola, Auli; Sulkava, Raimo; Kivimäki, Mika; Vahtera, Jussi; Partonen, Timo; Silander, Kaisa; Porkka-Heiskanen, Tarja

2017-01-01

Abstract Study Objectives: Tolerance to shift work varies; only some shift workers suffer from disturbed sleep, fatigue, and job-related exhaustion. Our aim was to explore molecular genetic risk factors for intolerance to shift work. Methods: We assessed intolerance to shift work with job-related exhaustion symptoms in shift workers using the emotional exhaustion subscale of the Maslach Burnout Inventory-General Survey, and carried out a genome-wide association study (GWAS) using Illumina’s Human610-Quad BeadChip (n = 176). The most significant findings were further studied in three groups of Finnish shift workers (n = 577). We assessed methylation in blood cells with the Illumina HumanMethylation450K BeadChip, and examined gene expression levels in the publicly available eGWAS Mayo data. Results: The second strongest signal identified in the GWAS (p = 2.3 × 10E-6) was replicated in two of the replication studies with p < .05 (p = 2.0 × 10E-4 when combining the replication studies) and indicated an association of job-related exhaustion in shift workers with rs12506228, located downstream of the melatonin receptor 1A gene (MTNR1A). The risk allele was also associated with reduced in silico gene expression levels of MTNR1A in brain tissue and suggestively associated with changes in DNA methylation in the 5' regulatory region of MTNR1A. Conclusions: These findings suggest that a variant near MTNR1A may be associated with job-related exhaustion in shift workers. The risk variant may exert its effect via epigenetic mechanisms, potentially leading to reduced melatonin signaling in the brain. These results could indicate a link between melatonin signaling, a key circadian regulatory mechanism, and tolerance to shift work. PMID:28364478

The Application of the Open Pharmacological Concepts Triple Store (Open PHACTS) to Support Drug Discovery Research

PubMed Central

Ratnam, Joseline; Zdrazil, Barbara; Digles, Daniela; Cuadrado-Rodriguez, Emiliano; Neefs, Jean-Marc; Tipney, Hannah; Siebes, Ronald; Waagmeester, Andra; Bradley, Glyn; Chau, Chau Han; Richter, Lars; Brea, Jose; Evelo, Chris T.; Jacoby, Edgar; Senger, Stefan; Loza, Maria Isabel; Ecker, Gerhard F.; Chichester, Christine

2014-01-01

Integration of open access, curated, high-quality information from multiple disciplines in the Life and Biomedical Sciences provides a holistic understanding of the domain. Additionally, the effective linking of diverse data sources can unearth hidden relationships and guide potential research strategies. However, given the lack of consistency between descriptors and identifiers used in different resources and the absence of a simple mechanism to link them, gathering and combining relevant, comprehensive information from diverse databases remains a challenge. The Open Pharmacological Concepts Triple Store (Open PHACTS) is an Innovative Medicines Initiative project that uses semantic web technology approaches to enable scientists to easily access and process data from multiple sources to solve real-world drug discovery problems. The project draws together sources of publicly-available pharmacological, physicochemical and biomolecular data, represents it in a stable infrastructure and provides well-defined information exploration and retrieval methods. Here, we highlight the utility of this platform in conjunction with workflow tools to solve pharmacological research questions that require interoperability between target, compound, and pathway data. Use cases presented herein cover 1) the comprehensive identification of chemical matter for a dopamine receptor drug discovery program 2) the identification of compounds active against all targets in the Epidermal growth factor receptor (ErbB) signaling pathway that have a relevance to disease and 3) the evaluation of established targets in the Vitamin D metabolism pathway to aid novel Vitamin D analogue design. The example workflows presented illustrate how the Open PHACTS Discovery Platform can be used to exploit existing knowledge and generate new hypotheses in the process of drug discovery. PMID:25522365

Dynamic dual-tracer MRI-guided fluorescence tomography to quantify receptor density in vivo

PubMed Central

Davis, Scott C.; Samkoe, Kimberley S.; Tichauer, Kenneth M.; Sexton, Kristian J.; Gunn, Jason R.; Deharvengt, Sophie J.; Hasan, Tayyaba; Pogue, Brian W.

2013-01-01

The up-regulation of cell surface receptors has become a central focus in personalized cancer treatment; however, because of the complex nature of contrast agent pharmacokinetics in tumor tissue, methods to quantify receptor binding in vivo remain elusive. Here, we present a dual-tracer optical technique for noninvasive estimation of specific receptor binding in cancer. A multispectral MRI-coupled fluorescence molecular tomography system was used to image the uptake kinetics of two fluorescent tracers injected simultaneously, one tracer targeted to the receptor of interest and the other tracer a nontargeted reference. These dynamic tracer data were then fit to a dual-tracer compartmental model to estimate the density of receptors available for binding in the tissue. Applying this approach to mice with deep-seated gliomas that overexpress the EGF receptor produced an estimate of available receptor density of 2.3 ± 0.5 nM (n = 5), consistent with values estimated in comparative invasive imaging and ex vivo studies. PMID:23671066

Fc receptors for mouse IgG1 on human monocytes: polymorphism and role in antibody-induced T cell proliferation.

PubMed

Tax, W J; Hermes, F F; Willems, R W; Capel, P J; Koene, R A

1984-09-01

In previous studies, it was shown that there is polymorphism in the mitogenic effect of mouse IgG1 monoclonal antibodies against the T3 antigen of human T cells. This polymorphism implies that IgG1 anti-T3 antibodies are not mitogenic for T cells from 30% of healthy individuals. The present results demonstrate that this polymorphism is caused by polymorphism of an Fc receptor for mouse IgG1, present on human monocytes. The Fc receptor for murine IgG1 could be detected by a newly developed rosetting assay on monocytes from all individuals responsive to the mitogenic effect of IgG1 anti-T3 antibodies. This Fc receptor was not detectable on monocytes from those individuals exhibiting no mitogenic responses to IgG1 anti-T3 monoclonal antibodies. Cross-linking of T3 antigens appears to be essential for antibody-induced mitosis of T cells, because mononuclear cells that did not proliferate in response to WT 31 (an IgG1 antibody against T3 antigen) showed a proliferative response to Sepharose beads coated with WT 31. The Fc receptor--if functionally present--may be involved in the cross-linking of T3 antigens through anti-T3 antibodies. Further evidence for the involvement of this Fc receptor in antibody-induced T cell proliferation was provided by inhibition studies. Immune complexes containing IgG1 antibodies were able to inhibit the proliferative response to IgG1 anti-T3 antibodies. This inhibition by immune complexes appears to be mediated through the monocyte Fc receptor for mouse IgG1. These findings are important for the interpretation of previously described inhibitory effects of anti-T cell monoclonal antibodies on T cell proliferation, and show that such inhibitory effects may be monocyte-mediated (via immune complexes) rather than caused by a direct involvement of the respective T cell antigens in T cell mitosis. The Fc receptor for mouse IgG1 plays a role in antibody-induced T cell proliferation. Its polymorphism may have important implications for the therapeutic use of IgG1 monoclonal antibodies.

Comprehensive functional analysis of N-linked glycans on Ebola virus GP1.

PubMed

Lennemann, Nicholas J; Rhein, Bethany A; Ndungo, Esther; Chandran, Kartik; Qiu, Xiangguo; Maury, Wendy

2014-01-28

Ebola virus (EBOV) entry requires the virion surface-associated glycoprotein (GP) that is composed of a trimer of heterodimers (GP1/GP2). The GP1 subunit contains two heavily glycosylated domains, the glycan cap and the mucin-like domain (MLD). The glycan cap contains only N-linked glycans, whereas the MLD contains both N- and O-linked glycans. Site-directed mutagenesis was performed on EBOV GP1 to systematically disrupt N-linked glycan sites to gain an understanding of their role in GP structure and function. All 15 N-glycosylation sites of EBOV GP1 could be removed without compromising the expression of GP. The loss of these 15 glycosylation sites significantly enhanced pseudovirion transduction in Vero cells, which correlated with an increase in protease sensitivity. Interestingly, exposing the receptor-binding domain (RBD) by removing the glycan shield did not allow interaction with the endosomal receptor, NPC1, indicating that the glycan cap/MLD domains mask RBD residues required for binding. The effects of the loss of GP1 N-linked glycans on Ca(2+)-dependent (C-type) lectin (CLEC)-dependent transduction were complex, and the effect was unique for each of the CLECs tested. Surprisingly, EBOV entry into murine peritoneal macrophages was independent of GP1 N-glycans, suggesting that CLEC-GP1 N-glycan interactions are not required for entry into this important primary cell. Finally, the removal of all GP1 N-glycans outside the MLD enhanced antiserum and antibody sensitivity. In total, our results provide evidence that the conserved N-linked glycans on the EBOV GP1 core protect GP from antibody neutralization despite the negative impact the glycans have on viral entry efficiency. Filovirus outbreaks occur sporadically throughout central Africa, causing high fatality rates among the general public and health care workers. These unpredictable hemorrhagic fever outbreaks are caused by multiple species of Ebola viruses, as well as Marburg virus. While filovirus vaccines and therapeutics are being developed, there are no licensed products. The sole viral envelope glycoprotein, which is a principal immunogenic target, contains a heavy shield of glycans surrounding the conserved receptor-binding domain. We find that disruption of this shield through targeted mutagenesis leads to an increase in cell entry, protease sensitivity, and antiserum/antibody sensitivity but is not sufficient to allow virion binding to the intracellular receptor NPC1. Therefore, our studies provide evidence that filoviruses maintain glycoprotein glycosylation to protect against proteases and antibody neutralization at the expense of efficient entry. Our results unveil interesting insights into the unique entry process of filoviruses and potential immune evasion tactics of the virus.

Immune System and Its Link to Rheumatic Diseases

MedlinePlus

... Keep me signed in Passwords are Case Sensitive. Ex. Enter smith as follows: Smith Forgot Username/Password? ... Erythematosus (Juvenile) Takayasu's Arteritis Tendinitis & Bursitis Tumor Necrosis Factor Receptor Associated Periodic Syndrome (Juvenile) Vasculitis Enfermedades y ...

Genetics Home Reference: leptin receptor deficiency

MedlinePlus

... Ferraz-Amaro I, Dattani MT, Ercan O, Myhre AG, Retterstol L, Stanhope R, Edge JA, McKenzie S, Lessan ... qualified healthcare professional . About Selection Criteria for Links Data Files & API Site Map Subscribe Customer Support USA. ...

Differential regulation of the transcriptional activity of the glucocorticoid receptor through site-specific phosphorylation.

PubMed

Kumar, Raj; Calhoun, William J

2008-12-01

Post-translational modifications such as phosphorylation are known to play an important role in the gene regulation by the transcription factors including the nuclear hormone receptor superfamily of which the glucocorticoid receptor (GR) is a member. Protein phosphorylation often switches cellular activity from one state to another. Like many other transcription factors, the GR is a phosphoprotein, and phosphorylation plays an important role in the regulation of GR activity. Cell signaling pathways that regulate phosphorylation of the GR and its associated proteins are important determinants of GR function under various physiological conditions. While the role of many phosphorylation sites in the GR is still not fully understood, the role of others is clearer. Several aspects of transcription factor function, including DNA binding affinity, interaction of transactivation domains with the transcription initiation complex, and shuttling between the cytoplasmic compartments, have all been linked to site-specific phosphorylation. All major phosphorylation sites in the human GR are located in the N-terminal domain including the major transactivation domain, AF1. Available literature clearly indicates that many of these potential phosphorylation sites are substrates for multiple kinases, suggesting the potential for a very complex regulatory network. Phosphorylated GR interacts favorably with critical coregulatory proteins and subsequently enhances transcriptional activity. In addition, the activities and specificities of coregulators may be subject to similar regulation by phosphorylation. Regulation of the GR activity due to phosphorylation appears to be site-specific and dependent upon specific cell signaling cascade. Taken together, site-specific phosphorylation and related kinase pathways play an important role in the action of the GR, and more precise mechanistic information will lead to fuller understanding of the complex nature of gene regulation by the GR- and related transcription factors. This review provides currently available information regarding the role of GR phosphorylation in its action, and highlights the possible underlying mechanisms of action.

OCD is associated with an altered association between sensorimotor gating and cortical and subcortical 5-HT1b receptor binding

PubMed Central

Pittenger, Christopher; Adams, Thomas. G.; Gallezot, Jean-Dominique; Crowley, Michael J.; Nabulsi, Nabeel; Ropchan, James; Gao, Hong; Kichuk, Stephen A.; Simpson, Ryan; Billingslea, Eileen; Hannestad, Jonas; Bloch, Michael; Mayes, Linda; Bhagwagar, Zubin; Carson, Richard E.

2016-01-01

Obsessive-compulsive disorder (OCD) is characterized by impaired sensorimotor gating, as measured using prepulse inhibition (PPI). This effect may be related to abnormalities in the serotonin (5-HT) system. 5-HT1B agonists can impair PPI, produce OCD-like behaviors in animals, and exacerbate OCD symptoms in humans. We measured 5-HT1B receptor availability using 11C-P943 positron emission tomography (PET) in unmedicated, non-depressed OCD patients (n = 12) and matched healthy controls (HC; n = 12). Usable PPI data were obtained from 20 of these subjects (10 from each group). There were no significant main effects of OCD diagnosis on 5-HT1B receptor availability (11C-P943 BPND); however, the relationship between PPI and 11C-P943 BPND differed dramatically and significantly between groups. 5-HT1B receptor availability in the basal ganglia and thalamus correlated positively with PPI in controls; these correlations were lost or even reversed in the OCD group. In cortical regions there were no significant correlations with PPI in controls, but widespread positive correlations in OCD patients. Positive correlations between 5-HT1B receptor availability and PPI were consistent across diagnostic groups only in two structures, the orbitofrontal cortex and the amygdala. Differential associations of 5-HT1B receptor availability with PPI in patients suggest functionally important alterations in the serotonergic regulation of cortical/subcortical balance in OCD. PMID:26919057

Relationship between Job Stress and 5-HT2A Receptor Polymorphisms on Self-Reported Sleep Quality in Physicians in Urumqi (Xinjiang, China): A Cross-Sectional Study

PubMed Central

Ge, Hua; Jiang, Yu; Zhang, Chen; Liu, Jiwen

2018-01-01

The serotonin receptor (5-HTR) plays a key role in sleep quality regulation. Job-related stress is an important factor that influences sleep quality. However, few reports on the interaction between 5-HTR2A polymorphisms and job stress, and how they may impact upon sleep quality are available. Therefore this study investigated the effects of job stress, 5-HTR2A polymorphisms, and their interaction on sleep quality, in physicians. Using a two-stage stratified sampling method, 918 participants were initially invited to participate in the study. After screening for study inclusion and exclusion criteria, 504 subjects were eventually included in the study. Job stress and sleep quality were assessed using the Job Stress Survey (JSS) and Pittsburgh Sleep Quality Index (PSQI), respectively. The 5-HTR2A receptor gene polymorphisms T102C and -1438G/A of were determined using polymerase chain reaction-restriction fragment length polymorphism. Job stress was significantly associated with sleep quality. High levels of job stress were linked to a higher risk of poor sleep quality compared to low or moderate levels [odds ratio (OR) = 2.909, 95% confidence interval (CI): 1.697–4.986]. High levels of stress may reduce subjects’ sleep quality, leading to an increase the likelihood of sleep disturbances and subsequent daytime dysfunction. The 5-HTR2A receptor gene polymorphism T102C was not significantly associated with sleep quality in this study, however, the -1438G/A polymorphism was significantly associated with sleep quality. The GG genotype of the -1438G/A polymorphism was linked to poorer sleep quality. When compared with subjects with low job-related stress levels×AG/AA genotype (OR = 2.106, 95% CI: 1.278–3.471), physicians with high job-related stress levels×GG genotype had a higher risk of experiencing poor sleep quality (OR = 13.400, 95% CI: 3.143–57.137). The findings of our study indicate that job stress and 5-HTR2A receptor gene polymorphisms are associated with sleep quality in physicians. Subjects with high job stress level or/and the -1438G/A GG genotype were more likely to report poor sleep quality, and furthermore, their combination effect on sleep quality was higher than their independent effects, so it may be suggested that job-related stress and genes have a cumulative effect on sleep quality; that is, stress can increase the risk of poor sleep quality, but this effect is worse in a group of people with specific gene polymorphisms. PMID:29883419

Relationship between Job Stress and 5-HT2A Receptor Polymorphisms on Self-Reported Sleep Quality in Physicians in Urumqi (Xinjiang, China): A Cross-Sectional Study.

PubMed

Gao, Xiaoyan; Ge, Hua; Jiang, Yu; Lian, Yulong; Zhang, Chen; Liu, Jiwen

2018-05-21

The serotonin receptor (5-HTR) plays a key role in sleep quality regulation. Job-related stress is an important factor that influences sleep quality. However, few reports on the interaction between 5-HTR2A polymorphisms and job stress, and how they may impact upon sleep quality are available. Therefore this study investigated the effects of job stress, 5-HTR2A polymorphisms, and their interaction on sleep quality, in physicians. Using a two-stage stratified sampling method, 918 participants were initially invited to participate in the study. After screening for study inclusion and exclusion criteria, 504 subjects were eventually included in the study. Job stress and sleep quality were assessed using the Job Stress Survey (JSS) and Pittsburgh Sleep Quality Index (PSQI), respectively. The 5-HTR2A receptor gene polymorphisms T102C and -1438G/A of were determined using polymerase chain reaction-restriction fragment length polymorphism. Job stress was significantly associated with sleep quality. High levels of job stress were linked to a higher risk of poor sleep quality compared to low or moderate levels [odds ratio (OR) = 2.909, 95% confidence interval (CI): 1.697⁻4.986]. High levels of stress may reduce subjects’ sleep quality, leading to an increase the likelihood of sleep disturbances and subsequent daytime dysfunction. The 5-HTR2A receptor gene polymorphism T102C was not significantly associated with sleep quality in this study, however, the -1438G/A polymorphism was significantly associated with sleep quality. The GG genotype of the -1438G/A polymorphism was linked to poorer sleep quality. When compared with subjects with low job-related stress levels×AG/AA genotype (OR = 2.106, 95% CI: 1.278⁻3.471), physicians with high job-related stress levels×GG genotype had a higher risk of experiencing poor sleep quality (OR = 13.400, 95% CI: 3.143⁻57.137). The findings of our study indicate that job stress and 5-HTR2A receptor gene polymorphisms are associated with sleep quality in physicians. Subjects with high job stress level or/and the -1438G/A GG genotype were more likely to report poor sleep quality, and furthermore, their combination effect on sleep quality was higher than their independent effects, so it may be suggested that job-related stress and genes have a cumulative effect on sleep quality; that is, stress can increase the risk of poor sleep quality, but this effect is worse in a group of people with specific gene polymorphisms.

[Receptor specificity of human enteroviruses].

PubMed

Fadeev, F A; Sergeev, A G; Novoselov, A V

2008-01-01

The review presents the currently available data on the receptor specificity of enteroviruses. It discusses whether changes in the receptor specificity of enteroviruses may play a role in their in vitro and in vivo reproduction.

The relationship between reward and punishment processing and the 5-HT1A receptor as shown by PET.

PubMed

Faulkner, Paul; Selvaraj, Sudhakar; Pine, Alex; Howes, Oliver D; Roiser, Jonathan P

2014-07-01

The serotonin (5-HT) system has been reported to be involved in decision-making. A key component of this neurotransmitter system is the 5-HT1A receptor, and research is beginning to show how this receptor can influence decision-making. However, this relationship has rarely been studied in humans. This study assessed whether individual variability in 5-HT1A availability correlates with decision-making in healthy volunteers. We measured regional availability of the 5-HT1A receptor in the hippocampal complex and striatum using positron emission tomography and correlated this with performance on two decision-making tasks measuring sensitivity to probability, rewards and punishments and temporal discounting, respectively. No relationship between decision-making behaviour and 5-HT1A availability in the striatum was found. However, a positive correlation was detected between participants' 5-HT1A availability in the hippocampal complex and their sensitivity to the probability of winning. Furthermore, there was a negative correlation between the degree to which participants discounted future rewards and 5-HT1A availability in the hippocampal complex. These data support a role for the 5-HT1A receptor in the aberrant decision-making that can occur in neuropsychiatric disorders such as depression.

Metabotropic and ionotropic glutamate receptors regulate calcium channel currents in salamander retinal ganglion cells

PubMed Central

Shen, Wen; Slaughter, Malcolm M

1998-01-01

Glutamate suppressed high-voltage-activated barium currents (IBa,HVA) in tiger salamander retinal ganglion cells. Both ionotropic (iGluR) and metabotropic (mGluR) receptors contributed to this calcium channel inhibition. Trans-ACPD (1-aminocyclopentane-trans-1S,3R-dicarboxylic acid), a broad-spectrum metabotropic glutamate receptor agonist, suppressed a dihydropyridine-sensitive barium current. Kainate, an ionotropic glutamate receptor agonist, reduced an ω-conotoxin GVIA-sensitive current. The relative effectiveness of selective agonists indicated that the predominant metabotropic receptor was the L-2-amino-4-phosphonobutyrate (l-AP4)-sensitive, group III receptor. This receptor reversed the action of forskolin, but this was not responsible for calcium channel suppression. l-AP4 raised internal calcium concentration. Antagonists of phospholipase C, inositol trisphosphate (IP3) receptors and ryanodine receptors inhibited the action of metabotropic agonists, indicating that group III receptor transduction was linked to this pathway. The action of kainate was partially suppressed by BAPTA, by calmodulin antagonists and by blockers of calmodulin-dependent phosphatase. Suppression by kainate of the calcium channel current was more rapid when calcium was the charge carrier, instead of barium. The results indicate that calcium influx through kainate-sensitive glutamate receptors can activate calmodulin, which stimulates phosphatases that may directly suppress voltage-sensitive calcium channels. Thus, ionotropic and metabotropic glutamate receptors inhibit distinct calcium channels. They could act synergistically, since both increase internal calcium. These pathways provide negative feedback that can reduce calcium influx when ganglion cells are depolarized. PMID:9660896

Center of Excellence in Biotechnology (Research)

DTIC Science & Technology

1993-03-01

1990) "Canine X-linked Muscular Dystrophy : Morphologic Lesions", J. Neurol Sci, 29. 1-23. F. Walker, E. Nice, L. Fabri, F.J. Moy, J-F. Liu, R. Wu...antidepressmats, and anesthetics. In this program, the mRNAs for the muscle and neuronal types of the receptor have been expressed in yeast, and have shown to...been used in chemical kinetic measurements of receptor function in neuronal PC12 cells, muscle BC3HI cells and XenoQfs oocytes. Another principal area of

Src-JNK Potentiation of Estrogen Receptor AF-1; Mechanism, and Role in Estrogen Action in Breast Cancer

DTIC Science & Technology

2002-08-01

an increase in estrogen receptor activity. A second objective is to understand the potential role of Src in estrogen induced mammary ductal development ...bPcis i on to The Ser-ilS-dependent link wt GR- t KaroBio AB, a Swedish pharmaceutical development company with CBP is in addition to the Ser-1l8...the ECL detection kit (Amersham Pharmacia Biotech ). phoresis, stained with Coomassic Blue to monitor expression, and sub- Fluorescence Microscopy

Epidermal growth factor receptor and integrins control force-dependent vinculin recruitment to E-cadherin junctions.

PubMed

Sehgal, Poonam; Kong, Xinyu; Wu, Jun; Sunyer, Raimon; Trepat, Xavier; Leckband, Deborah

2018-03-20

This study reports novel findings that link E-cadherin (also known as CDH1)-mediated force-transduction signaling to vinculin targeting to intercellular junctions via epidermal growth factor receptor (EGFR) and integrins. These results build on previous findings that demonstrated that mechanically perturbed E-cadherin receptors activate phosphoinositide 3-kinase and downstream integrins in an EGFR-dependent manner. Results of this study show that this EGFR-mediated kinase cascade controls the force-dependent recruitment of vinculin to stressed E-cadherin complexes - a key early signature of cadherin-based mechanotransduction. Vinculin targeting requires its phosphorylation at tyrosine 822 by Abl family kinases (hereafter Abl), but the origin of force-dependent Abl activation had not been identified. We now present evidence that integrin activation, which is downstream of EGFR signaling, controls Abl activation, thus linking E-cadherin to Abl through a mechanosensitive signaling network. These findings place EGFR and integrins at the center of a positive-feedback loop, through which force-activated E-cadherin signals regulate vinculin recruitment to cadherin complexes in response to increased intercellular tension.This article has an associated First Person interview with the first author of the paper. © 2018. Published by The Company of Biologists Ltd.

Receptor Tyrosine Kinase Ubiquitination and De-Ubiquitination in Signal Transduction and Receptor Trafficking

PubMed Central

Critchley, William R.; Pellet-Many, Caroline; Ringham-Terry, Benjamin; Zachary, Ian C.; Ponnambalam, Sreenivasan

2018-01-01

Receptor tyrosine kinases (RTKs) are membrane-based sensors that enable rapid communication between cells and their environment. Evidence is now emerging that interdependent regulatory mechanisms, such as membrane trafficking, ubiquitination, proteolysis and gene expression, have substantial effects on RTK signal transduction and cellular responses. Different RTKs exhibit both basal and ligand-stimulated ubiquitination, linked to trafficking through different intracellular compartments including the secretory pathway, plasma membrane, endosomes and lysosomes. The ubiquitin ligase superfamily comprising the E1, E2 and E3 enzymes are increasingly implicated in this post-translational modification by adding mono- and polyubiquitin tags to RTKs. Conversely, removal of these ubiquitin tags by proteases called de-ubiquitinases (DUBs) enables RTK recycling for another round of ligand sensing and signal transduction. The endocytosis of basal and activated RTKs from the plasma membrane is closely linked to controlled proteolysis after trafficking and delivery to late endosomes and lysosomes. Proteolytic RTK fragments can also have the capacity to move to compartments such as the nucleus and regulate gene expression. Such mechanistic diversity now provides new opportunities for modulating RTK-regulated cellular responses in health and disease states. PMID:29543760

Androgen Receptor (AR) in Cardiovascular Diseases

PubMed Central

Huang, Chiung-Kuei; Lee, Soo Ok; Chang, Eugene; Pang, Haiyan; Chang, Chawnshang

2016-01-01

Cardiovascular diseases (CVDs) are still the highest leading cause of death worldwide. Several risk factors have been linked to CVDs, including smoking, diabetes, hyperlipidemia, and gender among others. Sex hormones, especially the androgen and its receptor, androgen receptor (AR), have been linked to many diseases with a clear gender difference. Here, we summarize androgen/AR effects on CVDs, including hypertension, stroke, atherosclerosis, abdominal aortic aneurysm (AAA), myocardial hypertrophy, and heart failure, as well as metabolic syndrome/diabetes and their impacts on CVDs. Androgen/AR signaling exacerbates hypertension and anti-androgens may suppress hypertension. Androgen/AR signaling plays dual roles in strokes, depending on different kinds of factors, but generally males have a higher incidence of strokes than females. Androgen and AR differentially modulate atherosclerosis. Androgen deficiency causes elevated lipid accumulation to enhance atherosclerosis, but targeting AR in selective cells without altering serum androgen levels would suppress atherosclerosis progression. Androgen/AR signaling is crucial in AAA development and progression, and targeting androgen/AR profoundly restricts AAA progression. Men have increased cardiac hypertrophy as compared to age-matched women that may be due to androgens. Finally, androgen/AR plays important roles in contributing to obesity and insulin/leptin resistance to increase the metabolic syndrome. PMID:26769913

Structure and signalling functions of C3 receptors on human B cells.

PubMed

Frade, R

1990-03-01

CR1 (C3b receptor) and CR2 (C3d/EBV receptor) are two C3 receptors expressed on B lymphocytes. CR1 and CR2 have structural similarities and their cross-linking at the B cell surface by antibodies or specific ligands in multimeric forms induce B cell activation. However, activation of human B cells through cell surface interactions or by intracellular protein kinase C activators leads to phosphorylation of CR2 but not CR1. CR2 is phosphorylated on serine and tyrosine residues. Analysis of post-membrane events associated with CR2 revealed intracellular interactions of CR2 with p53, a plasma membrane anti-oncogene-encoded phosphoprotein, and with p120, a nuclear phosphoribonucleoprotein. These intracellular interactions probably represent important steps in the signalling functions of CR2.

Glycoprotein interactions in paramyxovirus fusion

PubMed Central

Iorio, Ronald M; Melanson, Vanessa R; Mahon, Paul J

2009-01-01

The Paramyxoviridae are enveloped, negative-stranded RNA viruses, some of which recognize sialic acid-containing receptors, while others recognize specific proteinaceous receptors. The major cytopathic effect of paramyxovirus infection is membrane fusion-induced syncytium formation. Paramyxoviruses are unusual in that the receptor-binding and fusion-promoting activities reside on two different spike structures, the attachment and fusion glycoproteins, respectively. For most paramyxoviruses, this distribution of functions requires a mechanism by which the two processes can be linked for the promotion of fusion. This is accomplished by a virus-specific interaction between the two proteins. An increasing body of evidence supports the notion that members of this family of viruses utilize this glycoprotein interaction in different ways in order to mediate the regulation of the fusion protein activation, depending on the type of receptor utilized by the virus. PMID:20161127

Diffusion Barriers, Mechanical Forces, and the Biophysics of Phagocytosis.

PubMed

Ostrowski, Philip P; Grinstein, Sergio; Freeman, Spencer A

2016-07-25

Phagocytes recognize and eliminate pathogens, alert other tissues of impending threats, and provide a link between innate and adaptive immunity. They also maintain tissue homeostasis, consuming dead cells without causing alarm. The receptor engagement, signal transduction, and cytoskeletal rearrangements underlying phagocytosis are paradigmatic of other immune responses and bear similarities to macropinocytosis and cell migration. We discuss how the glycocalyx restricts access to phagocytic receptors, the processes that enable receptor engagement and clustering, and the remodeling of the actin cytoskeleton that controls the mobility of membrane proteins and lipids and provides the mechanical force propelling the phagocyte membrane toward and around the phagocytic prey. Copyright © 2016 Elsevier Inc. All rights reserved.

Hormonal receptors and vascular endothelial growth factor in juvenile nasopharyngeal angiofibroma: immunohistochemical and tissue microarray analysis.

PubMed

Liu, Zhuofu; Wang, Jingjing; Wang, Huan; Wang, Dehui; Hu, Li; Liu, Quan; Sun, Xicai

2015-01-01

This work demonstrated that juvenile nasopharyngeal angiofibromas (JNAs) express high levels of hormone receptors and vascular endothelial growth factor (VEGF) compared with normal nasal mucosa. The interaction between hormone receptors and VEGF may be involved in the initiation and growth of JNA. JNA is a rare benign tumor that occurs almost exclusively in male adolescents. Although generally regarded as a hormone-dependent tumor, this has not been proven in previous studies. The aim of this study was to investigate the role of hormone receptors in JNA and the relationship with clinical characteristics. Standard immunohistochemical microarray analysis was performed on 70 JNA samples and 10 turbinate tissue samples. Specific antibodies for androgen receptor (AR), estrogen receptor-α (ER-α), estrogen receptor-β (ER-β), progesterone receptor (PR), and VEGF were examined, and the relationships of receptor expression with age, tumor stage, and bleeding were evaluated. RESULTS showed that JNA expressed ER-α (92.9%), ER-β (91.4%), AR (65.7%), PR (12.8%), and VEGF (95.7%) at different levels. High level of VEGF was linked to elevated ER-α and ER-β. There was no significant relationship between hormonal receptors and age at diagnosis, tumor stage or bleeding. However, overexpression of ER-α was found to be an indicator of poor prognosis (p = 0.031).

Pathophysiological roles of P2 receptors in glial cells.

PubMed

Abbracchio, Maria P; Verderio, Claudia

2006-01-01

Extracellular nucleotides act through specific receptors on target cells: the seven ionotropic P2X and the eight G protein-coupled P2Y receptors. All these receptors are expressed by brain astroglia and microglia. In astrocytes, P2 receptors have been implicated in short-term calcium-dependent cell-cell communication. Upon mechanical stimulation or activation by other transmitters, astrocytes release ATP and respond to ATP with a propagating wave of intracellular calcium increases, allowing a homotypic astrocyte-astrocyte communication, as well as an heterotypic signalling which also involves neurons, oligodendrocytes and microglia. Astrocytic P2 receptors also mediate reactive astrogliosis, a reaction contributing to neuronal death in neurodegenerative diseases. Signalling leading to inflammatory astrogliosis involves induction of cyclo-oxygenase 2 through stimulation of ERK1,2 and of the transcriptional factors AP-1 and NF-kappaB. Microglia also express several P2 receptors linked to intracellular calcium increases. P2 receptor subtypes are differentially regulated by typical proinflammatory signals for these cells (e.g. lipopolysaccharide), suggesting specific roles in brain immune responses. Globally, these findings highlight the roles of P2 receptors in glial cell pathophysiology suggesting a contribution to neurodegenerative diseases characterized by excessive gliosis and neuro-inflammation. They also open up the possibility of modulating brain damage by ligands selectively targeting the specific P2 receptor subtypes involved in the gliotic response.

Arrestin binds to different phosphorylated regions of the thyrotropin-releasing hormone receptor with distinct functional consequences.

PubMed

Jones, Brian W; Hinkle, Patricia M

2008-07-01

Arrestin binding to agonist-occupied phosphorylated G protein-coupled receptors typically increases the affinity of agonist binding, increases resistance of receptor-bound agonist to removal with high acid/salt buffer, and leads to receptor desensitization and internalization. We tested whether thyrotropin-releasing hormone (TRH) receptors lacking phosphosites in the C-terminal tail could form stable and functional complexes with arrestin. Fibroblasts from mice lacking arrestins 2 and 3 were used to distinguish between arrestin-dependent and -independent effects. Arrestin did not promote internalization or desensitization of a receptor that had key Ser/Thr phosphosites mutated to Ala (4Ala receptor). Nevertheless, arrestin greatly increased acid/salt resistance and the affinity of 4Ala receptor for TRH. Truncation of 4Ala receptor just distal to the key phosphosites (4AlaStop receptor) abolished arrestin-dependent acid/salt resistance but not the effect of arrestin on agonist affinity. Arrestin formed stable complexes with activated wild-type and 4Ala receptors but not with 4AlaStop receptor, as measured by translocation of arrestin-green fluorescent protein to the plasma membrane or chemical cross-linking. An arrestin mutant that does not interact with clathrin and AP2 did not internalize receptor but still promoted high affinity TRH binding, acid/salt resistance, and desensitization. A sterically restricted arrestin mutant did not cause receptor internalization or desensitization but did promote acid/salt resistance and high agonist affinity. The results demonstrate that arrestin binds to proximal or distal phosphosites in the receptor tail. Arrestin binding at either site causes increased agonist affinity and acid/salt resistance, but only the proximal phosphosites evoke the necessary conformational changes in arrestin for receptor desensitization and internalization.

Positive Association Between Limbic Metabotropic Glutamate Receptor 5 Availability and Novelty-Seeking Temperament in Humans: An 18F-FPEB PET Study.

PubMed

Leurquin-Sterk, Gil; Van den Stock, Jan; Crunelle, Cleo Lina; de Laat, Bart; Weerasekera, Akila; Himmelreich, Uwe; Bormans, Guy; Van Laere, Koen

2016-11-01

Heritable temperament traits have been linked to several neuropsychiatric illnesses, including disorders associated with metabotropic glutamate receptor 5 (mGluR5) and dopaminergic dysfunctions. Considering its modulating effect on neurotransmission, we hypothesized that cerebral mGluR5 availability is associated with temperament traits in healthy humans. Forty-four nonsmoking healthy volunteers (mean age ± SD, 40 ± 14 y; age range, 22-66 y; 22 women) were included in this cross-sectional investigation. Brain mGluR5 availability was quantified on both a voxel-by-voxel and a volume-of-interest basis using the total distribution volume of the radioligand 18 F-3-fluoro-5-[(pyridin-3-yl)ethynyl]benzonitrile ( 18 F-FPEB) with 90-min dynamic PET and arterial input function. Moreover, glutamate-glutamine concentrations in the anterior cingulate cortex were measured using MR spectroscopy. These measures were related to the temperament traits of the 240-item Cloninger temperament and character inventory using a regression analysis with age and sex as nuisance variables. High novelty-seeking temperament was robustly associated with increased mGluR5 availability in various regions including the thalamus (r = 0.71; the strongest association), amygdala, parahippocampus, insula, anterior and posterior cingulate cortex, and several primary sensory areas (all r > 0.58; P < 0.05, corrected for familywise error). These associations were specific because no correlations were found with other temperament scales or with spectroscopic measures of glutamatergic transmission. Overall, these data posit mGluR5 in key paralimbic areas as a strong determinant of the temperament trait novelty seeking. These data add to our understanding of how brain neurochemistry accounts for the variation in human behavior and strongly support further research on mGluR5 as a potential therapeutic target in neuropsychiatric disorders associated with abnormal novelty-seeking behaviors. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Thrombin-receptor agonist peptides, in contrast to thrombin itself, are not full agonists for activation and signal transduction in human platelets in the absence of platelet-derived secondary mediators.

PubMed Central

Lau, L F; Pumiglia, K; Côté, Y P; Feinstein, M B

1994-01-01

Synthetic thrombin receptor peptides (TRPs), comprising the first 6-14 amino acids of the new N-terminus tethered ligand of the thrombin receptor that is generated by thrombin's proteolytic activity, were reported to activate platelets equally with thrombin itself and are considered to be full agonists [Vu et al. (1991) Cell 64, 1057-1068]. Using aspirin plus ADP-scavengers or the ADP-receptor antagonist adenosine 5'-[alpha-thio]triphosphate to prevent the secondary effects of the potent agonists that are normally released from stimulated platelets (i.e. ADP and thromboxane A2), we assessed the direct actions of thrombin and TRPs (i.e. TRP42-47 and TRP42-55). Compared with thrombin, under these conditions, TRPs: (1) failed to aggregate platelets completely; (2) produced less activation of glycoprotein (GP)IIb-IIIa; (3) did not cause association of GPIIb and pp60c-src with the cytoskeleton; and (4) caused less alpha-granule secretion, phosphorylation of cytoplasmic phospholipase A2, arachidonic acid release and phosphatidyl inositol (PtdOH) production. Furthermore, TRPs induced transient increases in protein phosphorylation mediated by protein kinase C and protein tyrosine phosphorylation, whereas these same responses to thrombin were greater and more sustained. Hirudin added after thrombin accelerated protein dephosphorylation, thereby mimicking the rate of spontaneous dephosphorylation seen after stimulation by TRPs. Platelets totally desensitized to very high concentrations of TRPs, by prior exposure to maximally effective concentrations of the peptides, remained responsive to alpha- and gamma-thrombins. Thrombin-stimulated PtdOH production in permeabilized platelets desensitized to TRPs was abolished by guanosine 5'-[beta-thio]diphosphate (GDP[beta S]), as in normal platelets. These results are discussed in terms of the allosteric Ternary Complex Model for G-protein linked receptors [Samama et al. (1993) J. Biol. Chem. 268, 4625-4636]. We conclude that: (1) TRPs are partial agonists for the thrombin receptor and produce incomplete receptor desensitization in keeping with their lower intrinsic activity; (2) thrombin's effects in platelets, even in TRP-desensitized platelets, are entirely mediated through the recently cloned G-protein linked receptor, and (3) thrombin's ability to produce sustained signals, compared with TRPs, may require the continued progressive proteolytic activation of naive thrombin receptors. Images Figure 3 PMID:7526841

A Highly Conserved Salt Bridge Stabilizes the Kinked Conformation of β2,3-Sheet Essential for Channel Function of P2X4 Receptors.

PubMed

Zhao, Wen-Shan; Sun, Meng-Yang; Sun, Liang-Fei; Liu, Yan; Yang, Yang; Huang, Li-Dong; Fan, Ying-Zhe; Cheng, Xiao-Yang; Cao, Peng; Hu, You-Min; Li, Lingyong; Tian, Yun; Wang, Rui; Yu, Ye

2016-04-08

Significant progress has been made in understanding the roles of crucial residues/motifs in the channel function of P2X receptors during the pre-structure era. The recent structural determination of P2X receptors allows us to reevaluate the role of those residues/motifs. Residues Arg-309 and Asp-85 (rat P2X4 numbering) are highly conserved throughout the P2X family and were involved in loss-of-function polymorphism in human P2X receptors. Previous studies proposed that they participated in direct ATP binding. However, the crystal structure of P2X demonstrated that those two residues form an intersubunit salt bridge located far away from the ATP-binding site. Therefore, it is necessary to reevaluate the role of this salt bridge in P2X receptors. Here, we suggest the crucial role of this structural element both in protein stability and in channel gating rather than direct ATP interaction and channel assembly. Combining mutagenesis, charge swap, and disulfide cross-linking, we revealed the stringent requirement of this salt bridge in normal P2X4 channel function. This salt bridge may contribute to stabilizing the bending conformation of the β2,3-sheet that is structurally coupled with this salt bridge and the α2-helix. Strongly kinked β2,3 is essential for domain-domain interactions between head domain, dorsal fin domain, right flipper domain, and loop β7,8 in P2X4 receptors. Disulfide cross-linking with directions opposing or along the bending angle of the β2,3-sheet toward the α2-helix led to loss-of-function and gain-of-function of P2X4 receptors, respectively. Further insertion of amino acids with bulky side chains into the linker between the β2,3-sheet or the conformational change of the α2-helix, interfering with the kinked conformation of β2,3, led to loss-of-function of P2X4 receptors. All these findings provided new insights in understanding the contribution of the salt bridge between Asp-85 and Arg-309 and its structurally coupled β2,3-sheet to the function of P2X receptors. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Antinociception by systemically-administered acetaminophen (paracetamol) involves spinal serotonin 5-HT7 and adenosine A1 receptors, as well as peripheral adenosine A1 receptors.

PubMed

Liu, Jean; Reid, Allison R; Sawynok, Jana

2013-03-01

Acetaminophen (paracetamol) is a widely used analgesic, but its sites and mechanisms of action remain incompletely understood. Recent studies have separately implicated spinal adenosine A(1) receptors (A(1)Rs) and serotonin 5-HT(7) receptors (5-HT(7)Rs) in the antinociceptive effects of systemically administered acetaminophen. In the present study, we determined whether these two actions are linked by delivering a selective 5-HT(7)R antagonist to the spinal cord of mice and examining nociception using the formalin 2% model. In normal and A(1)R wild type mice, antinociception by systemic (i.p.) acetaminophen 300mg/kg was reduced by intrathecal (i.t.) delivery of the selective 5-HT(7)R antagonist SB269970 3μg. In mice lacking A(1)Rs, i.t. SB269970 did not reverse antinociception by systemic acetaminophen, indicating a link between spinal 5-HT(7)R and A(1)R mechanisms. We also explored potential roles of peripheral A(1)Rs in antinociception by acetaminophen administered both locally and systemically. In normal mice, intraplantar (i.pl.) acetaminophen 200μg produced antinociception in the formalin test, and this was blocked by co-administration of the selective A(1)R antagonist DPCPX 4.5μg. Acetaminophen administered into the contralateral hindpaw had no effect, indicating a local peripheral action. When acetaminophen was administered systemically, its antinociceptive effect was reversed by i.pl. DPCPX in normal mice; this was also observed in A(1)R wild type mice, but not in those lacking A(1)Rs. In summary, we demonstrate a link between spinal 5-HT(7)Rs and A(1)Rs in the spinal cord relevant to antinociception by systemic acetaminophen. Furthermore, we implicate peripheral A(1)Rs in the antinociceptive effects of locally- and systemically-administered acetaminophen. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Homology modeling, binding site identification and docking study of human angiotensin II type I (Ang II-AT1) receptor.

PubMed

Vyas, Vivek K; Ghate, Manjunath; Patel, Kinjal; Qureshi, Gulamnizami; Shah, Surmil

2015-08-01

Ang II-AT1 receptors play an important role in mediating virtually all of the physiological actions of Ang II. Several drugs (SARTANs) are available, which can block the AT1 receptor effectively and lower the blood pressure in the patients with hypertension. Currently, there is no experimental Ang II-AT1 structure available; therefore, in this study we modeled Ang II-AT1 receptor structure using homology modeling followed by identification and characterization of binding sites and thereby assessing druggability of the receptor. Homology models were constructed using MODELLER and I-TASSER server, refined and validated using PROCHECK in which 96.9% of 318 residues were present in the favoured regions of the Ramachandran plots. Various Ang II-AT1 receptor antagonist drugs are available in the market as antihypertensive drug, so we have performed docking study with the binding site prediction algorithms to predict different binding pockets on the modeled proteins. The identification of 3D structures and binding sites for various known drugs will guide us for the structure-based drug design of novel compounds as Ang II-AT1 receptor antagonists for the treatment of hypertension. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

EPA EcoBox Tools by Receptors - Biota

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Receptors

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

EPA EcoBox Tools by Receptors - References

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

Genetic and epigenetic regulatory mechanisms of the oxytocin receptor gene (OXTR) and the (clinical) implications for social behavior.

PubMed

Tops, Sanne; Habel, Ute; Radke, Sina

2018-03-12

Oxytocin and the oxytocin receptor (OXTR) play an important role in a large variety of social behaviors. The oxytocinergic system interacts with environmental cues and is highly dependent on interindividual factors. Deficits in this system have been linked to mental disorders associated with social impairments, such as autism spectrum disorder (ASD). This review focuses on the modulation of social behavior by alterations in two domains of the oxytocinergic system. We discuss genetic and epigenetic regulatory mechanisms and alterations in these mechanisms that were found to have clinical implications for ASD. We propose possible explanations how these alterations affect the biological pathways underlying the aberrant social behavior and point out avenues for future research. We advocate the need for integration studies that combine multiple measures covering a broad range of social behaviors and link these to genetic and epigenetic profiles. Copyright © 2018. Published by Elsevier Inc.

Evolution of mosquito preference for humans linked to an odorant receptor

PubMed Central

McBride, Carolyn S.; Baier, Felix; Omondi, Aman B.; Spitzer, Sarabeth A.; Lutomiah, Joel; Sang, Rosemary; Ignell, Rickard; Vosshall, Leslie B.

2014-01-01

Female mosquitoes are major vectors of human disease and the most dangerous are those that preferentially bite humans. A ‘domestic’ form of the mosquito Aedes aegypti has evolved to specialize in biting humans and is the major worldwide vector of dengue, yellow fever, and Chikungunya viruses. The domestic form coexists with an ancestral, animal-biting ‘forest’ form along the coast of Kenya. We collected the two forms, established laboratory colonies, and document striking divergence in preference for human versus animal odour. We further show that the evolution of preference for human odour in domestic mosquitoes is tightly linked to increases in the expression and ligand-sensitivity of the odorant receptor AaegOr4, which we found recognises a compound present at high levels in human odour. Our results provide a rare example of a gene contributing to behavioural evolution and provide insight into how disease-vectoring mosquitoes came to specialise on humans. PMID:25391959

[Severe type A insulin resistance syndrome due to a mutation in the insulin receptor gene].

PubMed

Ros, P; Colino-Alcol, E; Grasso, V; Barbetti, F; Argente, J

2015-01-01

Insulin resistance syndromes without lipodystrophy are an infrequent and heterogeneous group of disorders with variable clinical phenotypes, associated with hyperglycemia and hyperinsulinemia. The three conditions related to mutations in the insulin receptor gene are leprechaunism or Donohue syndrome, Rabson-Mendenhall syndrome, and Type A syndrome. A case is presented on a patient diagnosed with type A insulin resistance, defined by the triad of extreme insulin resistance, acanthosis nigricans, and hyperandrogenism, carrying a heterozygous mutation in exon 19 of the insulin receptor gene coding for its tyrosine kinase domain that is crucial for the catalytic activity of the receptor. The molecular basis of the syndrome is reviewed, focusing on the structure-function relationships of the insulin receptor, knowing that the criteria for survival are linked to residual insulin receptor function. It is also pointed out that, although type A insulin resistance appears to represent a somewhat less severe condition, these patients have a high morbidity and their treatment is still unsatisfactory. Copyright © 2014 Asociación Española de Pediatría. Published by Elsevier Espana. All rights reserved.

Oxytocin receptor mRNA expression in rat brain: implications for behavioral integration and reproductive success.

PubMed

Ostrowski, N L

1998-11-01

The nonapeptide, oxytocin (OT), has been implicated in a wide range of physiological, behavioral and pharmacological effects related to learning and memory, parturition and lactation, maternal and sexual behavior, and the formation of social attachments. Specific G-protein linked membrane bound OT receptors mediate OTs effects. The unavailability of highly selective pharmacological ligands that discriminate the OT receptor from the highly homologous vasopressin receptors (V1a, V1b and V2 subtypes) has made it difficult to confirm specific effects of oxytocin, particularly in brain regions where OT and multiple AVP receptor subtypes may be coexpressed. Here, data on the oxytocin receptor (OTR) messenger ribonucleic acid (mRNA) localization in brain are presented in the context of a model that proposes a reproductive state-dependent role for steroid-hormone restructuring of neural circuits, and a role for oxytocin in the integration of neural transmission in pathways subserving: (1) steroid-sensitive reproductive behaviors; (2) learning; and (3) reinforcement. It is hypothesized that social attachments emerge as a consequence of a conditioned association between OT-related activity in these pathways and the eliciting stimulus.

Progesterone receptors in the female lower urinary tract

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

Batra, S.C.; Iosif, C.S.

1987-11-01

When female estrogenized rabbits were injected i.v. with /sup 3/H-progesterone, the tritium concentration determined after one hour was about two to three times higher in urethra, urinary bladder and vagina than in the heart. High affinity progesterone receptors (KD = 1-2 nM) could be demonstrated in both cytoplasmic and nuclear fractions prepared from estrogenized rabbit urethra, bladder and vagina. The cytosolic receptor concentration in both urethra and bladder was about half of that in the vagina. The concentration of nuclear receptors in urethra was not significantly different from that in the vagina, but in the bladder the concentration was onlymore » about one fourth of that in the vagina or urethra. The mean KD of cytosolic receptors from bladder was significantly higher than the corresponding values in urethra and vagina. Progesterone binding sites in the bladder had a broader hormonal specificity than those in the urethra or vagina. The present demonstration of specific progesterone receptors in the female urethra might provide a possible link between estrogen progesterone interaction and the appearance of urinary incontinence during pregnancy in women.« less

Striatal dopamine D2/D3 receptor binding in pathological gambling is correlated with mood-related impulsivity

PubMed Central

Clark, Luke; Stokes, Paul R.; Wu, Kit; Michalczuk, Rosanna; Benecke, Aaf; Watson, Ben J.; Egerton, Alice; Piccini, Paola; Nutt, David J.; Bowden-Jones, Henrietta; Lingford-Hughes, Anne R.

2012-01-01

Pathological gambling (PG) is a behavioural addiction associated with elevated impulsivity and suspected dopamine dysregulation. Reduced striatal dopamine D2/D3 receptor availability has been reported in drug addiction, and may constitute a premorbid vulnerability marker for addictive disorders. The aim of the present study was to assess striatal dopamine D2/D3 receptor availability in PG, and its association with trait impulsivity. Males with PG (n = 9) and male healthy controls (n = 9) underwent [11C]-raclopride positron emission tomography imaging and completed the UPPS-P impulsivity scale. There was no significant difference between groups in striatal dopamine D2/D3 receptor availability, in contrast to previous reports in drug addiction. However, mood-related impulsivity (‘Urgency’) was negatively correlated with [11C]-raclopride binding potentials in the PG group. The absence of a group difference in striatal dopamine binding implies a distinction between behavioural addictions and drug addictions. Nevertheless, our data indicate heterogeneity in dopamine receptor availability in disordered gambling, such that individuals with high mood-related impulsivity may show differential benefits from dopamine-based medications. PMID:22776462

Evidence that the subunit structure of gonadotropin receptor is preserved during regression of rat corpus luteum

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

Hwang, J.; Menon, K.N.J.

1986-05-29

The level of hCG/LH receptor has been shown to undergo marked changes during the life span of rat corpus luteum. To evaluate whether these fluctuations are due to changes in the receptor subunit structure or receptor protein content, the /sup 125/I-hCG binding activity and the receptor subunit structure were determined during different time periods of pseudopregnancy. The maximum /sup 125/I-hCG binding activity was observed on day 7, after which it decreased by 20 and 45% on day 11 and day 14, respectively. The Scatchard analysis of /sup 125/I-hCG binding data showed that the decrease in binding activity was caused bymore » a change in the number of binding sites rather than a change in the binding affinity. The LH/hCG receptor in ovarian membranes obtained on days 7, 11 and 14 were characterized by the method of affinity cross-linking. All four subunits of the LH/hCG receptor were detected in the ovarian membranes at all stages while the intensity decreased parallel to a decrease in hCG binding from day 7 to day 14.« less

The Role of TAM Family Receptors in Immune Cell Function: Implications for Cancer Therapy

PubMed Central

Paolino, Magdalena; Penninger, Josef M.

2016-01-01

The TAM receptor protein tyrosine kinases—Tyro3, Axl, and Mer—are essential regulators of immune homeostasis. Guided by their cognate ligands Growth arrest-specific gene 6 (Gas6) and Protein S (Pros1), these receptors ensure the resolution of inflammation by dampening the activation of innate cells as well as by restoring tissue function through promotion of tissue repair and clearance of apoptotic cells. Their central role as negative immune regulators is highlighted by the fact that deregulation of TAM signaling has been linked to the pathogenesis of autoimmune, inflammatory, and infectious diseases. Importantly, TAM receptors have also been associated with cancer development and progression. In a cancer setting, TAM receptors have a dual regulatory role, controlling the initiation and progression of tumor development and, at the same time, the associated anti-tumor responses of diverse immune cells. Thus, modulation of TAM receptors has emerged as a potential novel strategy for cancer treatment. In this review, we discuss our current understanding of how TAM receptors control immunity, with a particular focus on the regulation of anti-tumor responses and its implications for cancer immunotherapy. PMID:27775650

Glycine receptor mechanism illuminated by electron cryo-microscopy

PubMed Central

Du, Juan; Lü, Wei; Wu, Shenping; Cheng, Yifan; Gouaux, Eric

2015-01-01

Summary The strychnine-sensitive glycine receptor (GlyR) mediates inhibitory synaptic transmission in the spinal cord and brainstem and is linked to neurological disorders including autism and hyperekplexia. Understanding of molecular mechanisms and pharmacology of GlyRs has been hindered by a dearth of high-resolution structures. Here we report electron cryo-microscopy structures of the α1 GlyR with strychnine, glycine, or glycine/ivermectin. Strychnine arrests the receptor in an antagonist-bound, closed ion channel state, glycine stabilizes the receptor in an agonist-bound open channel state, and the glycine/ivermectin complex adopts a potentially desensitized or partially open state. Relative to the glycine-bound state, strychnine expands the agonist-binding pocket via outward movement of the C loop, promotes rearrangement of the extracellular and transmembrane domain ‘wrist’ interface, and leads to rotation of the transmembrane domain toward the pore axis, occluding the ion conduction pathway. These structures illuminate GlyR mechanism and define a rubric to interpret structures of Cys-loop receptors. PMID:26344198

A Viral Receptor Complementation Strategy to Overcome CAV-2 Tropism for Efficient Retrograde Targeting of Neurons.

PubMed

Li, Shu-Jing; Vaughan, Alexander; Sturgill, James Fitzhugh; Kepecs, Adam

2018-06-06

Retrogradely transported neurotropic viruses enable genetic access to neurons based on their long-range projections and have become indispensable tools for linking neural connectivity with function. A major limitation of viral techniques is that they rely on cell-type-specific molecules for uptake and transport. Consequently, viruses fail to infect variable subsets of neurons depending on the complement of surface receptors expressed (viral tropism). We report a receptor complementation strategy to overcome this by potentiating neurons for the infection of the virus of interest-in this case, canine adenovirus type-2 (CAV-2). We designed AAV vectors for expressing the coxsackievirus and adenovirus receptor (CAR) throughout candidate projection neurons. CAR expression greatly increased retrograde-labeling rates, which we demonstrate for several long-range projections, including some resistant to other retrograde-labeling techniques. Our results demonstrate a receptor complementation strategy to abrogate endogenous viral tropism and thereby facilitate efficient retrograde targeting for functional analysis of neural circuits. Copyright © 2018 Elsevier Inc. All rights reserved.

Lipids Derived from Virulent Francisella tularensis Broadly Inhibit Pulmonary Inflammation via Toll-Like Receptor 2 and Peroxisome Proliferator-Activated Receptor α

PubMed Central

Crane, Deborah D.; Ireland, Robin; Alinger, Joshua B.; Small, Pamela

2013-01-01

Francisella tularensis is a Gram-negative facultative intracellular pathogen that causes an acute lethal respiratory disease in humans. The heightened virulence of the pathogen is linked to its unique ability to inhibit Toll-like receptor (TLR)-mediated inflammatory responses. The bacterial component and mechanism of this inhibition are unknown. Here we show that lipids isolated from virulent but not attenuated strains of F. tularensis are not detected by host cells, inhibit production of proinflammatory cytokines by primary macrophages in response to known TLR ligands, and suppress neutrophil recruitment in vivo. We further show that lipid-mediated inhibition of inflammation is dependent on TLR2, MyD88, and the nuclear hormone and fatty acid receptor peroxisome proliferator-activated receptor α (PPARα). Pathogen lipid-mediated interference with inflammatory responses through the engagement of TLR2 and PPARα represents a novel manipulation of host signaling pathways consistent with the ability of highly virulent F. tularensis to efficiently evade host immune responses. PMID:23925884

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

PubMed Central

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

2010-01-01

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

Dissecting Impulsivity and its Relationships to Drug Addictions

PubMed Central

Ashenhurst, James R.; Cervantes, M. Catalina; James, Alexander S.; Groman, Stephanie M.; Pennington, Zachary T.

2015-01-01

Addictions are often characterized as forms of impulsive behavior. That said, it is often noted that impulsivity is a multidimensional construct, spanning several psychological domains. This review describes the relationship between varieties of impulsivity and addiction-related behaviors, the nature of the causal relationship between the two and the underlying neurobiological mechanisms that promote impulsive behaviors. We conclude that the available data strongly supports the notion that impulsivity is both a risk factor for, and a consequence of, drug and alcohol consumption. While the evidence indicating that subtypes of impulsive behavior are uniquely informative – either biologically or with respect to their relationships to addictions – is convincing, multiple lines of study link “distinct” subtypes of impulsivity to low dopamine D2 receptor function and perturbed serotonergic transmission, revealing shared mechanisms between the subtypes. Therefore, a common biological framework involving monoaminergic transmitters in key frontostriatal circuits may link multiple forms of impulsivity to drug self-administration and addiction-related behaviors. Further dissection of these relationships is needed before the next phase of genetic and genomic discovery will be able to reveal the biological sources of the vulnerability for addiction indexed by impulsivity. PMID:24654857

Contiguous 22.1-kb deletion embracing AVPR2 and ARHGAP4 genes at novel breakpoints leads to nephrogenic diabetes insipidus in a Chinese pedigree.

PubMed

Bai, Ying; Chen, Yibing; Kong, Xiangdong

2018-02-02

It has been reported that mutations in arginine vasopressin type 2 receptor (AVPR2) cause congenital X-linked nephrogenic diabetes insipidus (NDI). However, only a few cases of AVPR2 deletion have been documented in China. An NDI pedigree was included in this study, including the proband and his mother. All NDI patients had polyuria, polydipsia, and growth retardation. PCR mapping, long range PCR and sanger sequencing were used to identify genetic causes of NDI. A novel 22,110 bp deletion comprising AVPR2 and ARH4GAP4 genes was identified by PCR mapping, long range PCR and sanger sequencing. The deletion happened perhaps due to the 4-bp homologous sequence (TTTT) at the junctions of both 5' and 3' breakpoints. The gross deletion co-segregates with NDI. After analyzing available data of putative clinical signs of AVPR2 and ARH4GAP4 deletion, we reconsider the potential role of AVPR2 deletion in short stature. We identified a novel 22.1-kb deletion leading to X-linked NDI in a Chinese pedigree, which would increase the current knowledge in AVPR2 mutation.

Impaired plasticity of macrophages in X-linked adrenoleukodystrophy.

PubMed

Weinhofer, Isabelle; Zierfuss, Bettina; Hametner, Simon; Wagner, Magdalena; Popitsch, Niko; Machacek, Christian; Bartolini, Barbara; Zlabinger, Gerhard; Ohradanova-Repic, Anna; Stockinger, Hannes; Köhler, Wolfgang; Höftberger, Romana; Regelsberger, Günther; Forss-Petter, Sonja; Lassmann, Hans; Berger, Johannes

2018-05-30

X-linked adrenoleukodystrophy is caused by ATP-binding cassette transporter D1 (ABCD1) mutations and manifests by default as slowly progressive spinal cord axonopathy with associated demyelination (adrenomyloneuropathy). In 60% of male cases, however, X-linked adrenoleukodystrophy converts to devastating cerebral inflammation and demyelination (cerebral adrenoleukodystrophy) with infiltrating blood-derived monocytes and macrophages and cytotoxic T cells that can only be stopped by allogeneic haematopoietic stem cell transplantation or gene therapy at an early stage of the disease. Recently, we identified monocytes/macrophages but not T cells to be severely affected metabolically by ABCD1 deficiency. Here we found by whole transcriptome analysis that, although monocytes of patients with X-linked adrenoleukodystrophy have normal capacity for macrophage differentiation and phagocytosis, they are pro-inflammatory skewed also in patients with adrenomyloneuropathy in the absence of cerebral inflammation. Following lipopolysaccharide activation, the ingestion of myelin debris, normally triggering anti-inflammatory polarization, did not fully reverse the pro-inflammatory status of X-linked adrenoleukodystrophy macrophages. Immunohistochemistry on post-mortem cerebral adrenoleukodystrophy lesions reflected the activation pattern by prominent presence of enlarged lipid-laden macrophages strongly positive for the pro-inflammatory marker co-stimulatory molecule CD86. Comparative analyses of lesions with matching macrophage density in cases of cerebral adrenoleukodystrophy and acute multiple sclerosis showed a similar extent of pro-inflammatory activation but a striking reduction of anti-inflammatory mannose receptor (CD206) and haemoglobin-haptoglobin receptor (CD163) expression on cerebral adrenoleukodystrophy macrophages. Accordingly, ABCD1-deficiency leads to an impaired plasticity of macrophages that is reflected in incomplete establishment of anti-inflammatory responses, thus possibly contributing to the devastating rapidly progressive demyelination in cerebral adrenoleukodystrophy that only in rare cases arrests spontaneously. These findings emphasize monocytes/macrophages as crucial therapeutic targets for preventing or stopping myelin destruction in patients with X-linked adrenoleukodystrophy.

Protease-activated Receptor-4 Signaling and Trafficking Is Regulated by the Clathrin Adaptor Protein Complex-2 Independent of β-Arrestins*

PubMed Central

Smith, Thomas H.; Coronel, Luisa J.; Li, Julia G.; Dores, Michael R.; Nieman, Marvin T.; Trejo, JoAnn

2016-01-01

Protease-activated receptor-4 (PAR4) is a G protein-coupled receptor (GPCR) for thrombin and is proteolytically activated, similar to the prototypical PAR1. Due to the irreversible activation of PAR1, receptor trafficking is intimately linked to signal regulation. However, unlike PAR1, the mechanisms that control PAR4 trafficking are not known. Here, we sought to define the mechanisms that control PAR4 trafficking and signaling. In HeLa cells depleted of clathrin by siRNA, activated PAR4 failed to internalize. Consistent with clathrin-mediated endocytosis, expression of a dynamin dominant-negative K44A mutant also blocked activated PAR4 internalization. However, unlike most GPCRs, PAR4 internalization occurred independently of β-arrestins and the receptor's C-tail domain. Rather, we discovered a highly conserved tyrosine-based motif in the third intracellular loop of PAR4 and found that the clathrin adaptor protein complex-2 (AP-2) is important for internalization. Depletion of AP-2 inhibited PAR4 internalization induced by agonist. In addition, mutation of the critical residues of the tyrosine-based motif disrupted agonist-induced PAR4 internalization. Using Dami megakaryocytic cells, we confirmed that AP-2 is required for agonist-induced internalization of endogenous PAR4. Moreover, inhibition of activated PAR4 internalization enhanced ERK1/2 signaling, whereas Akt signaling was markedly diminished. These findings indicate that activated PAR4 internalization requires AP-2 and a tyrosine-based motif and occurs independent of β-arrestins, unlike most classical GPCRs. Moreover, these findings are the first to show that internalization of activated PAR4 is linked to proper ERK1/2 and Akt activation. PMID:27402844

Quetiapine and aripiprazole signal differently to ERK, p90RSK and c-Fos in mouse frontal cortex and striatum: role of the EGF receptor

PubMed Central

2014-01-01

Background Signaling pathways outside dopamine D2 receptor antagonism may govern the variable clinical profile of antipsychotic drugs (APD) in schizophrenia. One postulated mechanism causal to APD action may regulate synaptic plasticity and neuronal connectivity via the extracellular signal-regulated kinase (ERK) cascade that links G-protein coupled receptors (GPCR) and ErbB growth factor signaling, systems disturbed in schizophrenia. This was based upon our finding that the low D2 receptor affinity APD clozapine induced initial down-regulation and delayed epidermal growth factor receptor (EGFR or ErbB1) mediated activation of the cortical and striatal ERK response in vivo distinct from olanzapine or haloperidol. Here we map whether the second generation atypical APDs aripiprazole and quetiapine affect the EGFR-ERK pathway and its substrates p90RSK and c-Fos in mouse brain, given their divergent agonist and antagonist properties on dopaminergic transmission, respectively. Results In prefrontal cortex, aripiprazole triggered triphasic ERK phosphorylation that was EGFR-independent but had no significant effect in striatum. Conversely quetiapine did not alter cortical ERK signaling but elevated striatal ERK levels in an EGFR-dependent manner. Induction of ERK by aripiprazole did not affect p90RSK signaling but quetiapine decreased RSK phosphorylation within 1-hour of administration. The transcription factor c-Fos by comparison was a direct target of ERK phosphorylation induced by aripiprazole in cortex and quetiapine in striatum with protein levels in temporal alignment with that of ERK. Conclusions These data indicate that aripiprazole and quetiapine signal to specific nuclear targets of ERK, which for quetiapine occurs via an EGFR-linked mechanism, possibly indicating involvement of this system in its action. PMID:24552586

Glucose transporters are expressed in taste receptor cells

PubMed Central

Merigo, Flavia; Benati, Donatella; Cristofoletti, Mirko; Osculati, Francesco; Sbarbati, Andrea

2011-01-01

In the intestine, changes of sugar concentration generated in the lumen during digestion induce adaptive responses of glucose transporters in the epithelium. A close matching between the intestinal expression of glucose transporters and the composition and amount of the diet has been provided by several experiments. Functional evidence has demonstrated that the regulation of glucose transporters into enterocytes is induced by the sensing of sugar of the enteroendocrine cells through activation of sweet taste receptors (T1R2 and T1R3) and their associated elements of G-protein-linked signaling pathways (e.g. α-gustducin, phospholipase C β type 2 and transient receptor potential channel M5), which are signaling molecules also involved in the perception of sweet substances in the taste receptor cells (TRCs) of the tongue. Considering this phenotypical similarity between the intestinal cells and TRCs, we evaluated whether the TRCs themselves possess proteins of the glucose transport mechanism. Therefore, we investigated the expression of the typical intestinal glucose transporters (i.e. GLUT2, GLUT5 and SGLT1) in rat circumvallate papillae, using immunohistochemistry, double-labeling immunofluorescence, immunoelectron microscopy and reverse transcriptase-polymerase chain reaction analysis. The results showed that GLUT2, GLUT5 and SGLT1 are expressed in TRCs; their immunoreactivity was also observed in cells that displayed staining for α-gustducin and T1R3 receptor. The immunoelectron microscopic results confirmed that GLUT2, GLUT5 and SGLT1 were predominantly expressed in cells with ultrastructural characteristics of chemoreceptor cells. The presence of glucose transporters in TRCs adds a further link between chemosensory information and cellular responses to sweet stimuli that may have important roles in glucose homeostasis, contributing to a better understanding of the pathways implicated in glucose metabolism. PMID:21592100

Regulation of B Cell Functions by the Sialic Acid-Binding Receptors Siglec-G and CD22

PubMed Central

Jellusova, Julia; Nitschke, Lars

2011-01-01

B cell antigen receptor (BCR) engagement can lead to many different physiologic outcomes. To achieve an appropriate response, the BCR signal is interpreted in the context of other stimuli and several additional receptors on the B cell surface participate in the modulation of the signal. Two members of the Siglec (sialic acid-binding immunoglobulin-like lectin) family, CD22 and Siglec-G have been shown to inhibit the BCR signal. Recent findings indicate that the ability of these two receptors to bind sialic acids might be important to induce tolerance to self-antigens. Sialylated glycans are usually absent on microbes but abundant in higher vertebrates and might therefore provide an important tolerogenic signal. Since the expression of the specific ligands for Siglec-G and CD22 is tightly regulated and since Siglecs are not only able to bind their ligands in trans but also on the same cell surface this might provide additional mechanisms to control the BCR signal. Although both Siglec-G and CD22 are expressed on B cells and are able to inhibit BCR mediated signaling, they also show unique biological functions. While CD22 is the dominant regulator of calcium signaling on conventional B2 cells and also seems to play a role on marginal zone B cells, Siglec-G exerts its function mainly on B1 cells and influences their lifespan and antibody production. Both Siglec-G and CD22 have also recently been linked to toll-like receptor signaling and may provide a link in the regulation of the adaptive and innate immune response of B cells. PMID:22566885

Identification of Novel G Protein–Coupled Receptor 143 Ligands as Pharmacologic Tools for Investigating X-Linked Ocular Albinism

PubMed Central

De Filippo, Elisabetta; Manga, Prashiela; Schiedel, Anke C.

2017-01-01

Purpose GPR143 regulates melanosome biogenesis and organelle size in pigment cells. The mechanisms underlying receptor function remain unclear. G protein–coupled receptors (GPCRs) are excellent pharmacologic targets; thus, we developed and applied a screening approach to identify potential GPR143 ligands and chemical modulators. Methods GPR143 interacts with β-arrestin; we therefore established a β-arrestin recruitment assay to screen for compounds that modulate activity. Because GPR143 is localized intracellularly, screening with the wild-type receptor would be restricted to agents absorbed by the cell. For the screen we used a mutant receptor, which shows similar basal activity as the wild type but traffics to the plasma membrane. We tested two compound libraries and investigated validated hits for their effects on melanocyte pigmentation. Results GPR143, which showed high constitutive activity in the β-arrestin assay, was inhibited by several compounds. The three validated inhibitors (pimozide, niclosamide, and ethacridine lactate) were assessed for impact on melanocytes. Pigmentation and expression of tyrosinase, a key melanogenic enzyme, were reduced by all compounds. Because GPR143 appears to be constitutively active, these compounds may turn off its activity. Conclusions X-linked ocular albinism type I, characterized by developmental eye defects, results from GPR143 mutations. Identifying pharmacologic agents that modulate GPR143 activity will contribute significantly to our understanding of its function and provide novel tools with which to study GPCRs in melanocytes and retinal pigment epithelium. Pimozide, one of three GPR143 inhibitors identified in this study, maybe be a good lead structure for development of more potent compounds and provide a platform for design of novel therapeutic agents. PMID:28632878

Two signaling molecules share a phosphotyrosine-containing binding site in the platelet-derived growth factor receptor.

PubMed

Nishimura, R; Li, W; Kashishian, A; Mondino, A; Zhou, M; Cooper, J; Schlessinger, J

1993-11-01

Autophosphorylation sites of growth factor receptors with tyrosine kinase activity function as specific binding sites for Src homology 2 (SH2) domains of signaling molecules. This interaction appears to be a crucial step in a mechanism by which receptor tyrosine kinases relay signals to downstream signaling pathways. Nck is a widely expressed protein consisting exclusively of SH2 and SH3 domains, the overexpression of which causes cell transformation. It has been shown that various growth factors stimulate the phosphorylation of Nck and its association with autophosphorylated growth factor receptors. A panel of platelet-derived growth factor (PDGF) receptor mutations at tyrosine residues has been used to identify the Nck binding site. Here we show that mutation at Tyr-751 of the PDGF beta-receptor eliminates Nck binding both in vitro and in living cells. Moreover, the Y751F PDGF receptor mutant failed to mediate PDGF-stimulated phosphorylation of Nck in intact cells. A phosphorylated Tyr-751 is also required for binding of phosphatidylinositol-3 kinase to the PDGF receptor. Hence, the SH2 domains of p85 and Nck share a binding site in the PDGF receptor. Competition experiments with different phosphopeptides derived from the PDGF receptor suggest that binding of Nck and p85 is influenced by different residues around Tyr-751. Thus, a single tyrosine autophosphorylation site is able to link the PDGF receptor to two distinct SH2 domain-containing signaling molecules.

Metabotropic glutamate receptor subtype 5: molecular pharmacology, allosteric modulation and stimulus bias

PubMed Central

Sengmany, K

2015-01-01

The metabotropic glutamate receptor subtype 5 (mGlu5) is a family C GPCR that has been implicated in various neuronal processes and, consequently, in several CNS disorders. Over the past few decades, GPCR‐based drug discovery, including that for mGlu5 receptors, has turned considerable attention to targeting allosteric binding sites. Modulation of endogenous agonists by allosteric ligands offers the advantages of spatial and temporal fine‐tuning of receptor activity, increased selectivity and reduced adverse effects with the potential to elicit improved clinical outcomes. Further, with greater appreciation of the multifaceted nature of the transduction of mGlu5 receptor signalling, it is increasingly apparent that drug discovery must take into consideration unique receptor conformations and the potential for stimulus‐bias. This novel paradigm proposes that different ligands may differentially modulate distinct signalling pathways arising from the same receptor. We review our current understanding of the complexities of mGlu5 receptor signalling and regulation, and how these relate to allosteric ligands. Ultimately, a deeper appreciation of these relationships will provide the foundation for targeted drug design of compounds with increased selectivity, not only for the desired receptor but also for the desired signalling outcome from the receptor. Linked Articles This article is part of a themed section on Molecular Pharmacology of G Protein‐Coupled Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.20/issuetoc PMID:26276909

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

PubMed

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

2013-01-01

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

Computational Approaches for Decoding Select Odorant-Olfactory Receptor Interactions Using Mini-Virtual Screening

PubMed Central

Harini, K.; Sowdhamini, Ramanathan

2015-01-01

Olfactory receptors (ORs) belong to the class A G-Protein Coupled Receptor superfamily of proteins. Unlike G-Protein Coupled Receptors, ORs exhibit a combinatorial response to odors/ligands. ORs display an affinity towards a range of odor molecules rather than binding to a specific set of ligands and conversely a single odorant molecule may bind to a number of olfactory receptors with varying affinities. The diversity in odor recognition is linked to the highly variable transmembrane domains of these receptors. The purpose of this study is to decode the odor-olfactory receptor interactions using in silico docking studies. In this study, a ligand (odor molecules) dataset of 125 molecules was used to carry out in silico docking using the GLIDE docking tool (SCHRODINGER Inc Pvt LTD). Previous studies, with smaller datasets of ligands, have shown that orthologous olfactory receptors respond to similarly-tuned ligands, but are dramatically different in their efficacy and potency. Ligand docking results were applied on homologous pairs (with varying sequence identity) of ORs from human and mouse genomes and ligand binding residues and the ligand profile differed among such related olfactory receptor sequences. This study revealed that homologous sequences with high sequence identity need not bind to the same/ similar ligand with a given affinity. A ligand profile has been obtained for each of the 20 receptors in this analysis which will be useful for expression and mutation studies on these receptors. PMID:26221959

Retrieval of estradiol receptor in paraffin sections of resting porcine uteri by microwave treatment. Immunostaining patterns obtained with different primary antibodies.

PubMed

Sierralta, W D; Thole, H H

1996-05-01

The unmasking of estradiol receptor in paraffin sections of Bouin's-fixed uterine tissue from ovariectomized gilts was attained with microwave treatment. Immunocytochemistry of the receptor was performed using a polyclonal or five monoclonal antibodies, two of which are commercially available, reacting with different domains of the protein and an amplified-peroxidase system for detection. With five of the antibodies, a predominance of nuclear staining was observed in cells of endometrial glands, while one monoclonal antibody (13H2), reacting with the receptor's domain E, showed a preference for the cytoplasmic receptor. In stroma, all antibodies detected more receptor in nuclei than in cytoplasm. In epithelium, the commercially available antibody H222, our monoclonals 13H2 and HT65, and the polyclonal antibody 402 demonstrated more receptor in cytoplasmic than in nuclear areas. In myometrium, the nuclei from longitudinal and ring muscles were definitely stained with the antibodies. We conclude that the accessibilities of the antibody epitopes of the receptor differ according to the functional uterine cell type.

Anti-idiotypic antibody: A new strategy for the development of a growth hormone receptor antagonist.

PubMed

Lan, Hainan; Zheng, Xin; Khan, Muhammad Akram; Li, Steven

2015-11-01

In general, traditional growth hormone receptor antagonist can be divided into two major classes: growth hormone (GH) analogues and anti-growth hormone receptor (GHR) antibodies. Herein, we tried to explore a new class of growth hormone receptor (GHR) antagonist that may have potential advantages over the traditional antagonists. For this, we developed a monoclonal anti-idiotypic antibody growth hormone, termed CG-86. A series of experiments were conducted to characterize and evaluate this antibody, and the results from a competitive receptor-binding assay, Enzyme Linked Immunosorbent Assays (ELISA) and epitope mapping demonstrate that CG-86 behaved as a typical Ab2β. Next, we examined its antagonistic activity using in vitro cell models, and the results showed that CG-86 could effectively inhibit growth hormone receptor-mediated signalling and effectively inhibit growth hormone-induced Ba/F3-GHR638 proliferation. In summary, these studies show that an anti-idiotypic antibody (CG-86) has promise as a novel growth hormone receptor antagonist. Furthermore, the current findings also suggest that anti-idiotypic antibody may represent a novel strategy to produce a new class of growth hormone receptor antagonist, and this strategy may be applied with other cytokines or growth factors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Glycine and GABAA Ultra-Sensitive Ethanol Receptors as Novel Tools for Alcohol and Brain Research

PubMed Central

Naito, Anna; Muchhala, Karan H.; Asatryan, Liana; Trudell, James R.; Homanics, Gregg E.; Perkins, Daya I.; Alkana, Ronald L.

2014-01-01

A critical obstacle to developing effective medications to prevent and/or treat alcohol use disorders is the lack of specific knowledge regarding the plethora of molecular targets and mechanisms underlying alcohol (ethanol) action in the brain. To identify the role of individual receptor subunits in ethanol-induced behaviors, we developed a novel class of ultra-sensitive ethanol receptors (USERs) that allow activation of a single receptor subunit population sensitized to extremely low ethanol concentrations. USERs were created by mutating as few as four residues in the extracellular loop 2 region of glycine receptors (GlyRs) or γ-aminobutyric acid type A receptors (GABAARs), which are implicated in causing many behavioral effects linked to ethanol abuse. USERs, expressed in Xenopus oocytes and tested using two-electrode voltage clamp, demonstrated an increase in ethanol sensitivity of 100-fold over wild-type receptors by significantly decreasing the threshold and increasing the magnitude of ethanol response, without altering general receptor properties including sensitivity to the neurosteroid, allopregnanolone. These profound changes in ethanol sensitivity were observed across multiple subunits of GlyRs and GABAARs. Collectively, our studies set the stage for using USER technology in genetically engineered animals as a unique tool to increase understanding of the neurobiological basis of the behavioral effects of ethanol. PMID:25245406

Monocyte and plasma expression of TAM ligand and receptor in renal failure: Links to unregulated immunity and chronic inflammation.

PubMed

Lee, Iris J; Hilliard, Brendan A; Ulas, Mehriban; Yu, Daohai; Vangala, Chandan; Rao, Swati; Lee, Jean; Gadegbeku, Crystal A; Cohen, Philip L

2015-06-01

Chronic inflammation is increased in patients with chronic kidney disease (CKD) and contributes to cardiovascular morbidity and mortality. Specific immune mechanisms and pathways that drive and maintain chronic inflammation in CKD are not well described. The TAM ligands (Gas6 and protein S) and receptors (Axl and Mer) have been recently recognized as playing a prominent role in immune regulation. The receptors exist in both soluble and cell-bound forms; the soluble receptors (sAxl and sMer) are believed to compete with the bound receptors and thus inhibit their function. In this study, we determined the expression of cell-bound and soluble TAM proteins in patients with CKD. CKD patients had significantly lower expression of Mer in monocytes, yet increased expression of soluble TAM receptors sAxl and sMer in plasma compared to controls. The metalloproteinase ADAM 17, responsible for cleavage of Mer to its soluble form, was increased in patient monocytes. Elevated levels of soluble TAM receptors were more evident in patients with progressive renal failure. These observations suggest that functional deficiency of TAM receptor-mediated regulation of inflammation may contribute to chronic inflammation in patients with CKD. Copyright © 2015 Elsevier Inc. All rights reserved.

Dopamine D1 receptor density in the mPFC responds to cognitive demands and receptor turnover contributes to general cognitive ability in mice.

PubMed

Wass, Christopher; Sauce, Bruno; Pizzo, Alessandro; Matzel, Louis D

2018-03-14

In both humans and mice, performance on tests of intelligence or general cognitive ability (GCA) is related to dopamine D1 receptor-mediated activity in the prelimbic cortex, and levels of DRD1 mRNA predict the GCA of mice. Here we assessed the turnover rate of D1 receptors as well as the expression level of the D1 chaperone protein (DRiP78) in the medial PPC (mPFC) of mice to determine whether rate of receptor turnover was associated with variations in the GCA of genetically heterogeneous mice. Following assessment of GCA (aggregate performance on four diverse learning tests) mice were administered an irreversible dopamine receptor antagonist (EEDQ), after which the density of new D1 receptors were quantified. GCA was positively correlated with both the rate of D1 receptor recovery and levels of DRiP78. Additionally, the density of D1 receptors was observed to increase within 60 min (or less) in response to intense demands on working memory, suggesting that a pool of immature receptors was available to accommodate high cognitive loads. These results provide evidence that innate general cognitive abilities are related to D1 receptor turnover rates in the prefrontal cortex, and that an intracellular pool of immature D1 receptors are available to accommodate cognitive demands.

Lysophosphatidic acid induces chemotaxis in MC3T3-E1 osteoblastic cells

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

Masiello, Lisa M.; Fotos, Joseph S.; Galileo, Deni S.

2006-07-01

Lysophosphatidic acid (LPA) is a bioactive lipid that has pleiotropic effects on a variety of cell types and enhances the migration of endothelial and cancer cells, but it is not known if this lipid can alter osteoblast motility. We performed transwell migration assays using MC3T3-E1 osteoblastic cells and found LPA to be a potent chemotactic agent. Quantitative time-lapse video analysis of osteoblast migration after wounds were introduced into cell monolayers indicated that LPA stimulated both migration velocity and the average migration distance per cell. LPA also elicited substantial changes in cell shape and actin cytoskeletal structure; lipid-treated cells contained fewermore » stress fibers and displayed long membrane processes that were enriched in F-actin. Quantitative RT-PCR analysis showed that MC3T3-E1 cells express all four known LPA-specific G protein-coupled receptors (LPA1-LPA4) with a relative mRNA abundance of LPA1 > LPA4 > LPA2 >> LPA3. LPA-induced changes in osteoblast motility and morphology were antagonized by both pertussis toxin and Ki16425, a subtype-specific blocker of LPA1 and LPA3 receptor function. Cell migration in many cell types is linked to changes in intracellular Ca2+. Ki16425 also inhibited LPA-induced Ca2+ signaling in a dose-dependent manner, suggesting a link between LPA-induced Ca2+ transients and osteoblast chemotaxis. Our data show that LPA stimulates MC3T3-E1 osteoblast motility via a mechanism that is linked primarily to the G protein-coupled receptor LPA1.« less

Gene expression profiling reveals different molecular patterns in G-protein coupled receptor signaling pathways between early- and late-onset preeclampsia.

PubMed

Liang, Mengmeng; Niu, Jianmin; Zhang, Liang; Deng, Hua; Ma, Jian; Zhou, Weiping; Duan, Dongmei; Zhou, Yuheng; Xu, Huikun; Chen, Longding

2016-04-01

Early-onset preeclampsia and late-onset preeclampsia have been regarded as two different phenotypes with heterogeneous manifestations; To gain insights into the pathogenesis of the two traits, we analyzed the gene expression profiles in preeclamptic placentas. A whole genome-wide microarray was used to determine the gene expression profiles in placental tissues from patients with early-onset (n = 7; <34 weeks), and late-onset (n = 8; >36 weeks) preeclampsia and their controls who delivered preterm (n = 5; <34 weeks) or at term (n = 5; >36 weeks). Genes were termed differentially expressed if they showed a fold-change ≥ 2 and q-value < 0.05. Quantitative real-time reverse transcriptase PCR was used to verify the results. Western blotting was performed to verify the expressions of secreted genes at the protein level. Six hundred twenty-seven genes were differentially expressed in early-compared with late-onset preeclampsia (177 genes were up-regulated and 450 were down-regulated). Gene ontology analysis identified significant alterations in several biological processes; the top two were immune response and cell surface receptor linked signal transduction. Among the cell surface receptor linked signal transduction-related, differentially expressed genes, those involved in the G-protein coupled receptor protein signaling pathway were significantly enriched. G-protein coupled receptor signaling pathway related genes, such as GPR124 and MRGPRF, were both found to be down-regulated in early-onset preeclampsia. The results were consistent with those of western blotting that the abundance of GPR124 was lower in early-onset compared with late-onset preeclampsia. The different gene expression profiles reflect the different levels of transcription regulation between the two conditions and supported the hypothesis that they are separate disease entities. Moreover, the G-protein coupled receptor signaling pathway related genes may contribute to the mechanism underlying early- and late-onset preeclampsia. Copyright © 2016 Elsevier Ltd. All rights reserved.

Steered Molecular Dynamics Simulations Predict Conformational Stability of Glutamate Receptors.

PubMed

Musgaard, Maria; Biggin, Philip C

2016-09-26

The stability of protein-protein interfaces can be essential for protein function. For ionotropic glutamate receptors, a family of ligand-gated ion channels vital for normal function of the central nervous system, such an interface exists between the extracellular ligand binding domains (LBDs). In the full-length protein, the LBDs are arranged as a dimer of dimers. Agonist binding to the LBDs opens the ion channel, and briefly after activation the receptor desensitizes. Several residues at the LBD dimer interface are known to modulate desensitization, and conformational changes around these residues are believed to be involved in the state transition. The general hypothesis is that the interface is disrupted upon desensitization, and structural evidence suggests that the disruption might be substantial. However, when cross-linking the central part of this interface, functional data suggest that the receptor can still undergo desensitization, contradicting the hypothesis of major interface disruption. Here, we illustrate how opening the dimer interface using steered molecular dynamics (SMD) simulations, and analyzing the work values required, provides a quantitative measure for interface stability. For one subtype of glutamate receptors, which is regulated by ion binding to the dimer interface, we show that opening the interface without ions bound requires less work than with ions present, suggesting that ion binding indeed stabilizes the interface. Likewise, for interface mutants with longer-lived active states, the interface is more stable, while the work required to open the interface is reduced for less active mutants. Moreover, a cross-linked mutant can still undergo initial interface opening motions similar to the native receptor and at similar energetic cost. Thus, our results support that interface opening is involved in desensitization. Furthermore, they provide reconciliation of apparently opposing data and demonstrate that SMD simulations can give relevant biological insight into longer time scale processes without the need for expensive calculations.

Intermediate closed state for glycine receptor function revealed by cysteine cross-linking.

PubMed

Prevost, Marie S; Moraga-Cid, Gustavo; Van Renterghem, Catherine; Edelstein, Stuart J; Changeux, Jean-Pierre; Corringer, Pierre-Jean

2013-10-15

Pentameric ligand-gated ion channels (pLGICs) mediate signal transmission by coupling the binding of extracellular ligands to the opening of their ion channel. Agonist binding elicits activation and desensitization of pLGICs, through several conformational states, that are, thus far, incompletely characterized at the structural level. We previously reported for GLIC, a prokaryotic pLGIC, that cross-linking of a pair of cysteines at both sides of the extracellular and transmembrane domain interface stabilizes a locally closed (LC) X-ray structure. Here, we introduced the homologous pair of cysteines on the human α1 glycine receptor. We show by electrophysiology that cysteine cross-linking produces a gain-of-function phenotype characterized by concomitant constitutive openings, increased agonist potency, and equalization of efficacies of full and partial agonists. However, it also produces a reduction of maximal currents at saturating agonist concentrations without change of the unitary channel conductance, an effect reversed by the positive allosteric modulator propofol. The cross-linking thus favors a unique closed state distinct from the resting and longest-lived desensitized states. Fitting the data according to a three-state allosteric model suggests that it could correspond to a LC conformation. Its plausible assignment to a gating intermediate or a fast-desensitized state is discussed. Overall, our data show that relative movement of two loops at the extracellular-transmembrane interface accompanies orthosteric agonist-mediated gating.

X-linked nephrogenic diabetes insipidus mutations in North America and the Hopewell hypothesis.

PubMed Central

Bichet, D G; Arthus, M F; Lonergan, M; Hendy, G N; Paradis, A J; Fujiwara, T M; Morgan, K; Gregory, M C; Rosenthal, W; Didwania, A

1993-01-01

In X-linked nephrogenic diabetes insipidus (NDI) the urine of male patients is not concentrated after the administration of the antidiuretic hormone arginine-vasopressin. This disease is due to mutations in the V2 receptor gene that maps to chromosome region Xq28. In 1969, Bode and Crawford suggested that most NDI patients in North America shared common ancestors of Ulster Scot immigrants who arrived in Halifax in 1761 on the ship Hopewell. A link between this family and a large Utah kindred was also suggested. DNA was obtained from 17 affected male patients from the "Hopewell" kindred and from four additional families from Nova Scotia and New Brunswick who shared the same Xq28 NDI haplotype. The Utah kindred and two families (Q2, Q3) from Quebec were also studied. The "Hopewell" mutation, W71X, is a single base substitution (G-->A) that changes codon 71 from TGG (tryptophan) to TGA (stop). The W71X mutation was found in affected members of the Hopewell and of the four satellite families. The W71X mutation is the cause of X-linked NDI for the largest number of related male patients living in North America. Other families (Utah, Q2 and Q3) that are historically and ethnically unrelated bear other mutations in the V2 receptor gene. Images PMID:8104196

Contribution of vascular endothelial growth factor receptor-2 sialylation to the process of angiogenesis.

PubMed

Chiodelli, P; Rezzola, S; Urbinati, C; Federici Signori, F; Monti, E; Ronca, R; Presta, M; Rusnati, M

2017-11-23

Vascular endothelial growth factor receptor-2 (VEGFR2) is the main pro-angiogenic receptor expressed by endothelial cells (ECs). Using surface plasmon resonance, immunoprecipitation, enzymatic digestion, immunofluorescence and cross-linking experiments with specific sugar-binding lectins, we demonstrated that VEGFR2 bears both α,1-fucose and α(2,6)-linked sialic acid (NeuAc). However, only the latter is required for VEGF binding to VEGFR2 and consequent VEGF-dependent VEGFR2 activation and motogenic response in ECs. Notably, downregulation of β-galactoside α(2,6)-sialyltransferase expression by short hairpin RNA transduction inhibits VEGFR2 α(2,6) sialylation that is paralleled by an increase of β-galactoside α(2,3)-sialyltransferase expression. This results in an ex-novo α(2,3)-NeuAc sialylation of the receptor that functionally replaces the lacking α(2,6)-NeuAc, thus allowing VEGF/VEGFR2 interaction. In keeping with the role of VEGFR2 sialylation in angiogenesis, the α(2,6)-NeuAc-binding lectin Sambucus nigra (SNA) prevents VEGF-dependent VEGFR2 autophosphorylation and EC motility, proliferation and motogenesis. In addition, SNA exerts a VEGF-antagonist activity in tridimensional angiogenesis models in vitro and in the chick-embryo chorioallantoic membrane neovascularization assay and mouse matrigel plug assay in vivo. In conclusion, VEGFR2-associated NeuAc plays an important role in modulating VEGF/VEGFR2 interaction, EC pro-angiogenic activation and neovessel formation. VEGFR2 sialylation may represent a target for the treatment of angiogenesis-dependent diseases.

Adverse morphological development in embryonic zebrafish exposed to environmental concentrations of contaminants individually and in mixture.

PubMed

Kinch, Cassandra D; Kurrasch, Deborah M; Habibi, Hamid R

2016-06-01

Exposure to environmental contaminants has been linked to developmental and reproductive abnormalities leading to infertility, spontaneous abortion, reduced number of offspring, and metabolic disorders. In addition, there is evidence linking environmental contaminants and endocrine disruption to abnormal developmental rate, defects in heart and eye morphology, and alterations in behavior. Notably, these effects could not be explained by interaction with a single hormone receptor. Here, using a whole-organism approach, we investigated morphological changes to developing zebrafish caused by exposure to a number of environmental contaminants, including bisphenol A (BPA), di(2-ethylhexyl)phthalate (DEHP), nonylphenol, and fucosterol at concentrations measured in a local water body (Oldman River, AB), individually and in mixture. Exposure to nanomolar contaminant concentrations resulted in abnormal morphological development, including changes to body length, pericardia (heart), and the head. We also characterize the spatiotemporal expression profiles of estrogen, androgen, and thyroid hormone receptors to demonstrate that localization of these receptors might be mediating contaminant effects on development. Finally, we examined the effects of contaminants singly and in mixture. Combined, our results support the hypothesis that adverse effects of contaminants are not mediated by single hormone receptor signaling, and adversity of contaminants in mixture could not be predicted by simple additive effect of contaminants. The findings provide a framework for better understanding of developmental toxicity of environmental contaminants in zebrafish and other vertebrate species. Copyright © 2016 Elsevier B.V. All rights reserved.

G protein-coupled odorant receptors: From sequence to structure.

PubMed

de March, Claire A; Kim, Soo-Kyung; Antonczak, Serge; Goddard, William A; Golebiowski, Jérôme

2015-09-01

Odorant receptors (ORs) are the largest subfamily within class A G protein-coupled receptors (GPCRs). No experimental structural data of any OR is available to date and atomic-level insights are likely to be obtained by means of molecular modeling. In this article, we critically align sequences of ORs with those GPCRs for which a structure is available. Here, an alignment consistent with available site-directed mutagenesis data on various ORs is proposed. Using this alignment, the choice of the template is deemed rather minor for identifying residues that constitute the wall of the binding cavity or those involved in G protein recognition. © 2015 The Protein Society.

G protein-coupled odorant receptors: From sequence to structure

PubMed Central

de March, Claire A; Kim, Soo-Kyung; Antonczak, Serge; Goddard, William A; Golebiowski, Jérôme

2015-01-01

Odorant receptors (ORs) are the largest subfamily within class A G protein-coupled receptors (GPCRs). No experimental structural data of any OR is available to date and atomic-level insights are likely to be obtained by means of molecular modeling. In this article, we critically align sequences of ORs with those GPCRs for which a structure is available. Here, an alignment consistent with available site-directed mutagenesis data on various ORs is proposed. Using this alignment, the choice of the template is deemed rather minor for identifying residues that constitute the wall of the binding cavity or those involved in G protein recognition. PMID:26044705

Adenosine receptors regulate gap junction coupling of the human cerebral microvascular endothelial cells hCMEC/D3 by Ca2+ influx through cyclic nucleotide‐gated channels

PubMed Central

Bader, Almke; Bintig, Willem; Begandt, Daniela; Klett, Anne; Siller, Ina G.; Gregor, Carola; Schaarschmidt, Frank; Weksler, Babette; Romero, Ignacio; Couraud, Pierre‐Olivier; Hell, Stefan W.

2017-01-01

Key points Gap junction channels are essential for the formation and regulation of physiological units in tissues by allowing the lateral cell‐to‐cell diffusion of ions, metabolites and second messengers.Stimulation of the adenosine receptor subtype A2B increases the gap junction coupling in the human blood–brain barrier endothelial cell line hCMEC/D3.Although the increased gap junction coupling is cAMP‐dependent, neither the protein kinase A nor the exchange protein directly activated by cAMP were involved in this increase.We found that cAMP activates cyclic nucleotide‐gated (CNG) channels and thereby induces a Ca2+ influx, which leads to the increase in gap junction coupling.The report identifies CNG channels as a possible physiological link between adenosine receptors and the regulation of gap junction channels in endothelial cells of the blood–brain barrier. Abstract The human cerebral microvascular endothelial cell line hCMEC/D3 was used to characterize the physiological link between adenosine receptors and the gap junction coupling in endothelial cells of the blood–brain barrier. Expressed adenosine receptor subtypes and connexin (Cx) isoforms were identified by RT‐PCR. Scrape loading/dye transfer was used to evaluate the impact of the A2A and A2B adenosine receptor subtype agonist 2‐phenylaminoadenosine (2‐PAA) on the gap junction coupling. We found that 2‐PAA stimulated cAMP synthesis and enhanced gap junction coupling in a concentration‐dependent manner. This enhancement was accompanied by an increase in gap junction plaques formed by Cx43. Inhibition of protein kinase A did not affect the 2‐PAA‐related enhancement of gap junction coupling. In contrast, the cyclic nucleotide‐gated (CNG) channel inhibitor l‐cis‐diltiazem, as well as the chelation of intracellular Ca2+ with BAPTA, or the absence of external Ca2+, suppressed the 2‐PAA‐related enhancement of gap junction coupling. Moreover, we observed a 2‐PAA‐dependent activation of CNG channels by a combination of electrophysiology and pharmacology. In conclusion, the stimulation of adenosine receptors in hCMEC/D3 cells induces a Ca2+ influx by opening CNG channels in a cAMP‐dependent manner. Ca2+ in turn induces the formation of new gap junction plaques and a consecutive sustained enhancement of gap junction coupling. The report identifies CNG channels as a physiological link that integrates gap junction coupling into the adenosine receptor‐dependent signalling of endothelial cells of the blood–brain barrier. PMID:28075020

EPA EcoBox Tools by Receptors - Habitats and Ecosystems

EPA Pesticide Factsheets

Eco-Box is a toolbox for exposure assessors. Its purpose is to provide a compendium of exposure assessment and risk characterization tools that will present comprehensive step-by-step guidance and links to relevant exposure assessment data bases

G Protein-Coupled Kinin Receptors and Immunity Against Pathogens.

PubMed

Scharfstein, Julio; Ramos, Pablo I P; Barral-Netto, Manoel

2017-01-01

For decades, immunologists have considered the complement system as a paradigm of a proteolytic cascade that, acting cooperatively with the immune system, enhances host defense against infectious organisms. In recent years, advances made in thrombosis research disclosed a functional link between activated neutrophils, monocytes, and platelet-driven thrombogenesis. Forging a physical barrier, the fibrin scaffolds generated by synergism between the extrinsic and intrinsic (contact) pathways of coagulation entrap microbes within microvessels, limiting the systemic spread of infection while enhancing the clearance of pathogens by activated leukocytes. Insight from mice models of thrombosis linked fibrin formation via the intrinsic pathway to the autoactivation of factor XII (FXII) by negatively charged "contact" substances, such as platelet-derived polyphosphates and DNA from neutrophil extracellular traps. Following cleavage by FXIIa, activated plasma kallikrein (PK) initiates inflammation by liberating the nonapeptide bradykinin (BK) from an internal domain of high molecular weight kininogen (HK). Acting as a paracrine mediator, BK induces vasodilation and increases microvascular permeability via activation of endothelial B2R, a constitutively expressed subtype of kinin receptor. During infection, neutrophil-driven extravasation of plasma fuels inflammation via extravascular activation of the kallikrein-kinin system (KKS). Whether liberated by plasma-borne PK, tissue kallikrein, and/or microbial-derived proteases, the short-lived kinins activate immature dendritic cells via B2R, thus linking the infection-associated innate immunity/inflammation to the adaptive arm of immunity. As inflammation persists, a GPI-linked carboxypeptidase M removes the C-terminal arginine from the primary kinin, converting the B2R agonist into a high-affinity ligand for B1R, a GPCR subtype that is transcriptionally upregulated in injured/inflamed tissues. As reviewed here, lessons taken from studies of kinin receptor function in experimental infections have shed light on the complex proteolytic circuits that, acting at the endothelial interface, reciprocally couple immunity to the proinflammatory KKS. © 2017 Elsevier Inc. All rights reserved.

Logic modeling and the ridiculome under the rug

PubMed Central

2012-01-01

Logic-derived modeling has been used to map biological networks and to study arbitrary functional interactions, and fine-grained kinetic modeling can accurately predict the detailed behavior of well-characterized molecular systems; at present, however, neither approach comes close to unraveling the full complexity of a cell. The current data revolution offers significant promises and challenges to both approaches - and could bring them together as it has spurred the development of new methods and tools that may help to bridge the many gaps between data, models, and mechanistic understanding. Have you used logic modeling in your research? It would not be surprising if many biologists would answer no to this hypothetical question. And it would not be true. In high school biology we already became familiar with cartoon diagrams that illustrate basic mechanisms of the molecular machinery operating inside cells. These are nothing else but simple logic models. If receptor and ligand are present, then receptor-ligand complexes form; if a receptor-ligand complex exists, then an enzyme gets activated; if the enzyme is active, then a second messenger is being produced; and so on. Such chains of causality are the essence of logic models (Figure 1a). Arbitrary events and mechanisms are abstracted; relationships are simplified and usually involve just two possible conditions and three possible consequences. The presence or absence of one or more molecule, activity, or function, [some icons in the cartoon] will determine whether another one of them will be produced (created, up-regulated, stimulated) [a 'positive' link] or destroyed (degraded, down-regulated, inhibited) [a 'negative' link], or be unaffected [there is no link]. The icons and links often do not follow a standardized format, but when we look at such a cartoon diagram, we believe that we 'understand' how the system works. Because our brain is easily able to process these relationships, these diagrams allow us to answer two fundamental types of questions related to the system: why (are certain things happening)? What if (we make some changes)? PMID:23171629

Epidermal growth factor induction of front–rear polarity and migration in keratinocytes is mediated by integrin-linked kinase and ELMO2

PubMed Central

Ho, Ernest; Dagnino, Lina

2012-01-01

Epidermal growth factor (EGF) is a potent chemotactic and mitogenic factor for epidermal keratinocytes, and these properties are central for normal epidermal regeneration after injury. The involvement of mitogen-activated protein kinases as mediators of the proliferative effects of EGF is well established. However, the molecular mechanisms that mediate motogenic responses to this growth factor are not clearly understood. An obligatory step for forward cell migration is the development of front–rear polarity and formation of lamellipodia at the leading edge. We show that stimulation of epidermal keratinocytes with EGF, but not with other growth factors, induces development of front–rear polarity and directional migration through a pathway that requires integrin-linked kinase (ILK), Engulfment and Cell Motility-2 (ELMO2), integrin β1, and Rac1. Furthermore, EGF induction of front–rear polarity and chemotaxis require the tyrosine kinase activity of the EGF receptor and are mediated by complexes containing active RhoG, ELMO2, and ILK. Our findings reveal a novel link between EGF receptor stimulation, ILK-containing complexes, and activation of small Rho GTPases necessary for acquisition of front–rear polarity and forward movement. PMID:22160594

Epidermal growth factor induction of front-rear polarity and migration in keratinocytes is mediated by integrin-linked kinase and ELMO2.

PubMed

Ho, Ernest; Dagnino, Lina

2012-02-01

Epidermal growth factor (EGF) is a potent chemotactic and mitogenic factor for epidermal keratinocytes, and these properties are central for normal epidermal regeneration after injury. The involvement of mitogen-activated protein kinases as mediators of the proliferative effects of EGF is well established. However, the molecular mechanisms that mediate motogenic responses to this growth factor are not clearly understood. An obligatory step for forward cell migration is the development of front-rear polarity and formation of lamellipodia at the leading edge. We show that stimulation of epidermal keratinocytes with EGF, but not with other growth factors, induces development of front-rear polarity and directional migration through a pathway that requires integrin-linked kinase (ILK), Engulfment and Cell Motility-2 (ELMO2), integrin β1, and Rac1. Furthermore, EGF induction of front-rear polarity and chemotaxis require the tyrosine kinase activity of the EGF receptor and are mediated by complexes containing active RhoG, ELMO2, and ILK. Our findings reveal a novel link between EGF receptor stimulation, ILK-containing complexes, and activation of small Rho GTPases necessary for acquisition of front-rear polarity and forward movement.

IL-15 induces CD8+ T cells to acquire functional NK receptors capable of modulating cytotoxicity and cytokine secretion.

PubMed

Correia, Margareta P; Costa, Alexandra V; Uhrberg, Markus; Cardoso, Elsa M; Arosa, Fernando A

2011-05-01

During the last years several authors have described a small population of CD8+ T cells expressing NK receptors (NKRs). Although their origin remains largely unknown, we have recently demonstrated that IL-15 is capable of inducing NKR expression in purified human CD8+CD56- T cells. In this study we show that IL-15-driven NKR induction in CD8+ T cells was linked with CD56 de novo acquisition, consistent with an effector-memory phenotype, increased anti-apoptotic levels, high granzyme B/perforin expression and with the ability of displaying in vitro NK-like cytotoxicity. Interestingly, dissection of NKR functional outcome in IL-15-cultured CD8+ T cells revealed: (i) that NKG2D cross-linking was able per se to upregulate degranulation levels and (ii) that KIR and NKG2A cross-linking upregulated secretion of cytokines such as IFN-γ, TNF-α, IL-1β and IL-10. These results suggest that IL-15 is capable of differentiating CD8+ T cells into NK-like T cells displaying a regulatory phenotype. Copyright © 2010 Elsevier GmbH. All rights reserved.

Intimate association of Thy-1 and the T-cell antigen receptor with the CD45 tyrosine phosphatase

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

Volarevic, S.; Burns, C.M.; Sussman, J.J.

1990-09-01

Immunoprecipitation of Thy-1 from Triton X-100 detergent lysates of surface-iodinated and chemically cross-linked T cells precipitated at least first major and discrete bands. Four of these bands were identified as Thy-1, CD45 (a trasmembrane tyrosine phosphatase), a major histocompatibility complex-encoded class I molecule, and {beta}{sub 2}-microglobulin. Similar analyses revealed that CD45 was coprecipitated from lysates of cross-linker-treated cells by antibodies to the T-cell antigen receptor (TCR). The same pattern of coprecipitated bands was observed when digitonin was used to lyse untreated cells. Immunoprecipitation of Thy-1 or the TCR from lysates of cross-linked T cells precipitated CD45 tyrosine phosphatase activity. Calculationsmore » based upon the amounts of coprecipitated enzymatic activity or TCR {zeta} chain indicate that a substantial fraction of Thy-1 and TCR complexes can be cross-linked to CD45. These data support a model in which the dependence of Thy-1 signaling on TCR coexpression is due to their common interaction with a tyrosine phosphatase and provide a possible structural basis for the influence of CD45 on TCR-mediated signaling.« less

Structural Model for Covalent Adhesion of the Streptococcus pyogenes Pilus through a Thioester Bond*

PubMed Central

Linke-Winnebeck, Christian; Paterson, Neil G.; Young, Paul G.; Middleditch, Martin J.; Greenwood, David R.; Witte, Gregor; Baker, Edward N.

2014-01-01

The human pathogen Streptococcus pyogenes produces pili that are essential for adhesion to host surface receptors. Cpa, the adhesin at the pilus tip, was recently shown to have a thioester-containing domain. The thioester bond is believed to be important in adhesion, implying a mechanism of covalent attachment analogous to that used by human complement factors. Here, we have characterized a second active thioester-containing domain on Cpa, the N-terminal domain of Cpa (CpaN). Expression of CpaN in Escherichia coli gave covalently linked dimers. These were shown by x-ray crystallography and mass spectrometry to comprise two CpaN molecules cross-linked by the polyamine spermidine following reaction with the thioester bonds. This cross-linked CpaN dimer provides a model for the covalent attachment of Cpa to target receptors and thus the streptococcal pilus to host cells. Similar thioester domains were identified in cell wall proteins of other Gram-positive pathogens, suggesting that thioester domains are more widely used and provide a mechanism of adhesion by covalent bonding to target molecules on host cells that mimics that used by the human complement system to eliminate pathogens. PMID:24220033

75 FR 50768 - Government-Owned Inventions; Availability for Licensing

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-17

.... N-Methanocarba Adenosine Derivatives and Their Dendrimer Conjugates as A 3 Receptor Agonists... receptors and agonists and antagonists of P2Y receptors, such as P2Y 1 and P2Y 14 . Dendrimer conjugates may...

Differential action of small molecule HER kinase inhibitors on receptor heterodimerization: therapeutic implications.

PubMed

Sánchez-Martín, M; Pandiella, A

2012-07-01

Deregulation of ErbB/HER receptor tyrosine kinases has been linked to several types of cancer. The mechanism of activation of these receptors includes establishment of receptor dimers. Here, we have analyzed the action of different small molecule HER tyrosine kinase inhibitors (TKIs) on HER receptor dimerization. Breast cancer cell lines were treated with distinct TKIs and the formation of HER2-HER3 dimers was analyzed by coimmunoprecipitation and western blot or by Förster resonance energy transfer assays. Antibody-dependent cellular cytotoxicity was analyzed by measuring the release of lactate dehydrogenase and cell viability. Lapatinib and neratinib interfered with ligand-induced dimerization of HER receptors; while pelitinib, gefitinib, canertinib or erlotinib did not. Moreover, lapatinib and neratinib were able to disrupt previously formed receptor dimers. Structural analyses allowed the elucidation of the mechanism by which some TKIs prevent the formation of HER receptor dimers, while others do not. Experiments aimed at defining the functional importance of dimerization indicated that TKIs that impeded dimerization prevented down-regulation of HER2 receptors, and favored the action of trastuzumab. We postulate that TKIs that prevent dimerization and down-regulation of HER2 may augment the antitumoral action of trastuzumab, and this mechanism of action should be considered in the treatment of HER2 positive tumors which combine TKIs with antireceptor antibodies. Copyright © 2011 UICC.

Nuclear receptors and pathogenesis of pancreatic cancer

PubMed Central

Polvani, Simone; Tarocchi, Mirko; Tempesti, Sara; Galli, Andrea

2014-01-01

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with a median overall survival time of 5 mo and the five years survival less than 5%, a rate essentially unchanged over the course of the years. A well defined progression model of accumulation of genetic alterations ranging from single point mutations to gross chromosomal abnormalities has been introduced to describe the origin of this disease. However, due to the its subtle nature and concurring events PDAC cure remains elusive. Nuclear receptors (NR) are members of a large superfamily of evolutionarily conserved ligand-regulated DNA-binding transcription factors functionally involved in important cellular functions ranging from regulation of metabolism, to growth and development. Given the nature of their ligands, NR are very tempting drug targets and their pharmacological modulation has been widely exploited for the treatment of metabolic and inflammatory diseases. There are now clear evidences that both classical ligand-activated and orphan NR are involved in the pathogenesis of PDAC from its very early stages; nonetheless many aspects of their role are not fully understood. The purpose of this review is to highlight the striking connections that link peroxisome proliferator activated receptors, retinoic acid receptors, retinoid X receptor, androgen receptor, estrogen receptors and the orphan NR Nur, chicken ovalbumin upstream promoter transcription factor II and the liver receptor homologue-1 receptor to PDAC development, connections that could lead to the identification of novel therapies for this disease. PMID:25232244

The Role of Rab Proteins in Neuronal Cells and in the Trafficking of Neurotrophin Receptors

PubMed Central

Bucci, Cecilia; Alifano, Pietro; Cogli, Laura

2014-01-01

Neurotrophins are a family of proteins that are important for neuronal development, neuronal survival and neuronal functions. Neurotrophins exert their role by binding to their receptors, the Trk family of receptor tyrosine kinases (TrkA, TrkB, and TrkC) and p75NTR, a member of the tumor necrosis factor (TNF) receptor superfamily. Binding of neurotrophins to receptors triggers a complex series of signal transduction events, which are able to induce neuronal differentiation but are also responsible for neuronal maintenance and neuronal functions. Rab proteins are small GTPases localized to the cytosolic surface of specific intracellular compartments and are involved in controlling vesicular transport. Rab proteins, acting as master regulators of the membrane trafficking network, play a central role in both trafficking and signaling pathways of neurotrophin receptors. Axonal transport represents the Achilles' heel of neurons, due to the long-range distance that molecules, organelles and, in particular, neurotrophin-receptor complexes have to cover. Indeed, alterations of axonal transport and, specifically, of axonal trafficking of neurotrophin receptors are responsible for several human neurodegenerative diseases, such as Huntington’s disease, Alzheimer’s disease, amyotrophic lateral sclerosis and some forms of Charcot-Marie-Tooth disease. In this review, we will discuss the link between Rab proteins and neurotrophin receptor trafficking and their influence on downstream signaling pathways. PMID:25295627

Persistence of evolutionary memory: primordial six-transmembrane helical domain mu opiate receptors selectively linked to endogenous morphine signaling.

PubMed

Kream, Richard M; Sheehan, Melinda; Cadet, Patrick; Mantione, Kirk J; Zhu, Wei; Casares, Federico; Stefano, George B

2007-12-01

Biochemical, molecular and pharmacological evidence for two unique six-transmembrane helical (TMH) domain opiate receptors expressed from the micro opioid receptor (MOR) gene have been shown. Designated micro3 and micro4 receptors, both protein species are Class A rhodopsin-like members of the superfamily of G-protein coupled receptors but are selectively tailored to mediate the cellular regulatory effects of endogenous morphine and related morphinan alkaloids via stimulation of nitric oxide (NO) production and release. Both micro3 and micro4 receptors lack an amino acid sequence of approximately 90 amino acids that constitute the extracellular N-terminal and TMH1 domains and part of the first intracellular loop of the micro1 receptor, but retain the empirically defined ligand binding pocket distributed across conserved TMH2, TMH3, and TMH7 domains of the micro1 sequence. Additionally, the receptor proteins are terminated by unique intracellular C-terminal amino acid sequences that serve as putative coupling or docking domains required for constitutive NO synthase activation. Because the recognition profile of micro3 and micro4 receptors is restricted to rigid benzylisoquinoline alkaloids typified by morphine and its extended family of chemical congeners, it is hypothesized that conformational stabilization provided by interaction of extended extracellular N-terminal protein domains and the extracellular loops is required for binding of endogenous opioid peptides as well as synthetic flexible opiate alkaloids.

Sigma receptors [σRs]: biology in normal and diseased states

PubMed Central

Rousseaux, Colin G.; Greene, Stephanie F.

2016-01-01

Abstract This review compares the biological and physiological function of Sigma receptors [σRs] and their potential therapeutic roles. Sigma receptors are widespread in the central nervous system and across multiple peripheral tissues. σRs consist of sigma receptor one (σ1R) and sigma receptor two (σ2R) and are expressed in numerous regions of the brain. The sigma receptor was originally proposed as a subtype of opioid receptors and was suggested to contribute to the delusions and psychoses induced by benzomorphans such as SKF-10047 and pentazocine. Later studies confirmed that σRs are non-opioid receptors (not an µ opioid receptor) and play a more diverse role in intracellular signaling, apoptosis and metabolic regulation. σ1Rs are intracellular receptors acting as chaperone proteins that modulate Ca2+ signaling through the IP3 receptor. They dynamically translocate inside cells, hence are transmembrane proteins. The σ1R receptor, at the mitochondrial-associated endoplasmic reticulum membrane, is responsible for mitochondrial metabolic regulation and promotes mitochondrial energy depletion and apoptosis. Studies have demonstrated that they play a role as a modulator of ion channels (K+ channels; N-methyl-d-aspartate receptors [NMDAR]; inositol 1,3,5 triphosphate receptors) and regulate lipid transport and metabolism, neuritogenesis, cellular differentiation and myelination in the brain. σ1R modulation of Ca2+ release, modulation of cardiac myocyte contractility and may have links to G-proteins. It has been proposed that σ1Rs are intracellular signal transduction amplifiers. This review of the literature examines the mechanism of action of the σRs, their interaction with neurotransmitters, pharmacology, location and adverse effects mediated through them. PMID:26056947

Kainate Receptors Inhibit Glutamate Release Via Mobilization of Endocannabinoids in Striatal Direct Pathway Spiny Projection Neurons.

PubMed

Marshall, John J; Xu, Jian; Contractor, Anis

2018-04-18

Kainate receptors are members of the glutamate receptor family that function by both generating ionotropic currents through an integral ion channel pore and coupling to downstream metabotropic signaling pathways. They are highly expressed in the striatum, yet their roles in regulating striatal synapses are not known. Using mice of both sexes, we demonstrate that GluK2-containing kainate receptors expressed in direct pathway spiny projection neurons (dSPNs) inhibit glutamate release at corticostriatal synapses in the dorsolateral striatum. This inhibition requires postsynaptic kainate-receptor-mediated mobilization of a retrograde endocannabinoid (eCB) signal and activation of presynaptic CB1 receptors. This pathway can be activated during repetitive 25 Hz trains of synaptic stimulation, causing short-term depression of corticostriatal synapses. This is the first study to demonstrate a role for kainate receptors in regulating eCB-mediated plasticity at the corticostriatal synapse and demonstrates an important role for these receptors in regulating basal ganglia circuits. SIGNIFICANCE STATEMENT The GRIK2 gene, encoding the GluK2 subunit of the kainate receptor, has been linked to several neuropsychiatric and neurodevelopmental disorders including obsessive compulsive disorder (OCD). Perseverative behaviors associated with OCD are known to result from pathophysiological changes in the striatum and kainate receptor knock-out mice have striatal-dependent phenotypes. However, the role of kainate receptors in striatal synapses is not known. We demonstrate that GluK2-containing kainate receptors regulate corticostriatal synapses by mobilizing endocannabinoids from direct pathway spiny projection neurons. Synaptic activation of GluK2 receptors during trains of synaptic input causes short-term synaptic depression, demonstrating a novel role for these receptors in regulating striatal circuits. Copyright © 2018 the authors 0270-6474/18/383901-10$15.00/0.

The T160A hemagglutinin substitution affects not only receptor binding property but also transmissibility of H5N1 clade 2.3.4 avian influenza virus in guinea pigs.

PubMed

Gu, Min; Li, Qunhui; Gao, Ruyi; He, Dongchang; Xu, Yunpeng; Xu, Haixu; Xu, Lijun; Wang, Xiaoquan; Hu, Jiao; Liu, Xiaowen; Hu, Shunlin; Peng, Daxin; Jiao, Xinan; Liu, Xiufan

2017-02-06

We generated and characterized site-directed HA mutants on the genetic backbone of H5N1 clade 2.3.4 virus preferentially binding to α-2,3 receptors in order to identify the key determinants in hemagglutinin rendering the dual affinity to both α-2,3 (avian-type) and α-2,6 (human-type) linked sialic acid receptors of the current clade 2.3.4.4 H5NX subtype avian influenza reassortants. The results show that the T160A substitution resulted in the loss of a glycosylation site at 158N and led not only to enhanced binding specificity for human-type receptors but also transmissibility among guinea pigs, which could be considered as an important molecular marker for assessing pandemic potential of H5 subtype avian influenza isolates.

A moving view: subcellular trafficking processes in pattern recognition receptor-triggered plant immunity.

PubMed

Ben Khaled, Sara; Postma, Jelle; Robatzek, Silke

2015-01-01

A significant challenge for plants is to induce localized defense responses at sites of pathogen attack. Therefore, host subcellular trafficking processes enable accumulation and exchange of defense compounds, which contributes to the plant on-site defenses in response to pathogen perception. This review summarizes our current understanding of the transport processes that facilitate immunity, the significance of which is highlighted by pathogens reprogramming membrane trafficking through host cell translocated effectors. Prominent immune-related cargos of plant trafficking pathways are the pattern recognition receptors (PRRs), which must be present at the plasma membrane to sense microbes in the apoplast. We focus on the dynamic localization of the FLS2 receptor and discuss the pathways that regulate receptor transport within the cell and their link to FLS2-mediated immunity. One emerging theme is that ligand-induced late endocytic trafficking is conserved across different PRR protein families as well as across different plant species.

Phosphotyrosine signaling proteins that drive oncogenesis tend to be highly interconnected.

PubMed

Koytiger, Grigoriy; Kaushansky, Alexis; Gordus, Andrew; Rush, John; Sorger, Peter K; MacBeath, Gavin

2013-05-01

Mutation and overexpression of receptor tyrosine kinases or the proteins they regulate serve as oncogenic drivers in diverse cancers. To better understand receptor tyrosine kinase signaling and its link to oncogenesis, we used protein microarrays to systematically and quantitatively measure interactions between virtually every SH2 or PTB domain encoded in the human genome and all known sites of tyrosine phosphorylation on 40 receptor tyrosine kinases and on most of the SH2 and PTB domain-containing adaptor proteins. We found that adaptor proteins, like RTKs, have many high affinity bindings sites for other adaptor proteins. In addition, proteins that drive cancer, including both receptors and adaptor proteins, tend to be much more highly interconnected via networks of SH2 and PTB domain-mediated interactions than nononcogenic proteins. Our results suggest that network topological properties such as connectivity can be used to prioritize new drug targets in this well-studied family of signaling proteins.

IL-4 and IL-13 Receptor Signaling From 4PS to Insulin Receptor Substrate 2: There and Back Again, a Historical View

PubMed Central

Keegan, Achsah D.; Zamorano, Jose; Keselman, Aleksander; Heller, Nicola M.

2018-01-01

In this historical perspective, written in honor of Dr. William E. Paul, we describe the initial discovery of one of the dominant substrates for tyrosine phosphorylation stimulated by IL-4. We further describe how this “IL-4-induced phosphorylated substrate” (4PS) was characterized as a member of the insulin receptor substrate (IRS) family of large adaptor proteins that link IL-4 and insulin receptors to activation of the phosphatidyl-inositol 3′ kinase pathway as well as other downstream signaling pathways. The relative contribution of the 4PS/IRS pathway to the early models of IL-4-induced proliferation and suppression of apoptosis are compared to our more recent understanding of the complex interplay between positive and negative regulatory pathways emanating from members of the IRS family that impact allergic responses. PMID:29868002

IL-4 and IL-13 Receptor Signaling From 4PS to Insulin Receptor Substrate 2: There and Back Again, a Historical View.

PubMed

Keegan, Achsah D; Zamorano, Jose; Keselman, Aleksander; Heller, Nicola M

2018-01-01

In this historical perspective, written in honor of Dr. William E. Paul, we describe the initial discovery of one of the dominant substrates for tyrosine phosphorylation stimulated by IL-4. We further describe how this "IL-4-induced phosphorylated substrate" (4PS) was characterized as a member of the insulin receptor substrate (IRS) family of large adaptor proteins that link IL-4 and insulin receptors to activation of the phosphatidyl-inositol 3' kinase pathway as well as other downstream signaling pathways. The relative contribution of the 4PS/IRS pathway to the early models of IL-4-induced proliferation and suppression of apoptosis are compared to our more recent understanding of the complex interplay between positive and negative regulatory pathways emanating from members of the IRS family that impact allergic responses.

CD22 serves as a receptor for soluble IgM.

PubMed

Adachi, Takahiro; Harumiya, Satoru; Takematsu, Hiromu; Kozutsumi, Yasunori; Wabl, Matthias; Fujimoto, Manabu; Tedder, Thomas F

2012-01-01

CD22 (Siglec-2) is a B-cell membrane-bound lectin that recognizes glycan ligands containing α2,6-linked sialic acid (α2,6Sia) and negatively regulates signaling through the B-cell Ag receptor (BCR). Although CD22 has been investigated extensively, its precise function remains unclear due to acting multiple phases. Here, we demonstrate that CD22 is efficiently activated in trans by complexes of Ag and soluble IgM (sIgM) due to the presence of glycan ligands on sIgM. This result strongly suggests sIgM as a natural trans ligand for CD22. Also, CD22 appears to serve as a receptor for sIgM, which induces a negative feedback loop for B-cell activation similar to the Fc receptor for IgG (FcγRIIB). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed Central

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

1999-01-01

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

Granulocyte colony-stimulating factor receptor signaling in severe congenital neutropenia, chronic neutrophilic leukemia, and related malignancies.

PubMed

Dwivedi, Pankaj; Greis, Kenneth D

2017-02-01

Granulocyte colony-stimulating factor is a hematopoietic cytokine that stimulates neutrophil production and hematopoietic stem cell mobilization by initiating the dimerization of homodimeric granulocyte colony-stimulating factor receptor. Different mutations of CSF3R have been linked to a unique spectrum of myeloid disorders and related malignancies. Myeloid disorders caused by the CSF3R mutations include severe congenital neutropenia, chronic neutrophilic leukemia, and atypical chronic myeloid leukemia. In this review, we provide an analysis of granulocyte colony-stimulating factor receptor, various mutations, and their roles in the severe congenital neutropenia, chronic neutrophilic leukemia, and malignant transformation, as well as the clinical implications and some perspective on approaches that could expand our knowledge with respect to the normal signaling mechanisms and those associated with mutations in the receptor. Copyright © 2016 ISEH - International Society for Experimental Hematology. Published by Elsevier Inc. All rights reserved.

Characterization of opioid receptors that modulate nociceptive neurotransmission in the trigeminocervical complex

PubMed Central

Storer, R J; Akerman, S; Goadsby, P J

2003-01-01

Opioid agonists have been used for many years to treat all forms of headache, including migraine. We sought to characterize opioid receptors involved in craniovascular nociceptive pathways by in vivo microiontophoresis of μ-receptor agonists and antagonists onto neurons in the trigeminocervical complex of the cat. Cats were anaesthetized with α-chloralose 60 mg kg−1, i.p. and 20 mg kg−1, i.v. supplements after induction and surgical preparation using halothane. Units were identified in the trigeminocervical complex responding to supramaximal electrical stimulation of the superior sagittal sinus, and extracellular recordings of activity made. Seven- or nine-barrelled glass micropipettes incorporating tungsten recording electrodes in their centre barrels were used for microiontophoresis of test substances onto cell bodies. Superior sagittal sinus (SSS)-linked cells whose firing was evoked by microiontophoretic application of L-glutamate (n=8 cells) were reversibly inhibited by microiontophoresis of H2N-Tyr-D-Ala-Gly-N-Me-Phe-Gly-ol (DAMGO) (n=12), a selective μ-receptor agonist, in a dose dependent manner, but not by control ejection of sodium or chloride ions from a barrel containing saline. The inhibition by DAMGO of SSS-linked neurons activated with L-glutamate could be antagonized by microiontophoresis of selective μ-receptor antagonists D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP) or D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP), or both, in all cells tested (n=4 and 6, respectively). Local iontophoresis of DAMGO during stimulation of the superior sagittal sinus resulted in a reduction in SSS-evoked activity. This effect was substantially reversed 10 min after cessation of iontophoresis. The effect of DAMGO was markedly inhibited by co-iontophoresis of CTAP. Thus, we found that μ-receptors modulate nociceptive input to the trigeminocervical complex. Characterizing the sub-types of opioid receptors that influence trigeminovascular nociceptive transmission is an important component to understanding the pharmacology of this synapse, which is pivotal in primary neurovascular headache. PMID:12540522

Differential expression of the Nrf2-linked genes in pediatric septic shock.

PubMed

Grunwell, Jocelyn R; Weiss, Scott L; Cvijanovich, Natalie Z; Allen, Geoffrey L; Thomas, Neal J; Freishtat, Robert J; Anas, Nick; Meyer, Keith; Checchia, Paul A; Shanley, Thomas P; Bigham, Michael T; Fitzgerald, Julie; Howard, Kelli; Frank, Erin; Harmon, Kelli; Wong, Hector R

2015-09-17

Experimental data from animal models of sepsis support a role for a transcription factor, nuclear erythroid-related factor 2 p45-related factor 2 (Nrf2), as a master regulator of antioxidant and detoxifying genes and intermediary metabolism during stress. Prior analysis of a pediatric septic shock transcriptomic database showed that the Nrf2 response is a top 5 upregulated signaling pathway in early pediatric septic shock. We conducted a focused analysis of 267 Nrf2-linked genes using a multicenter, genome-wide expression database of 180 children with septic shock 10 years of age or younger and 53 healthy controls. The analysis involved RNA isolated from whole blood within 24 h of pediatric intensive care unit admission for septic shock and a false discovery rate of 5 %. We compared differentially expressed genes from (1) patients with septic shock and healthy controls and (2) across validated gene expression-based subclasses of pediatric septic shock (endotypes A and B) using several bioinformatic methods. We found upregulation of 123 Nrf2-linked genes in children with septic shock. The top gene network represented by these genes contained primarily enzymes with oxidoreductase activity involved in cellular lipid metabolism that were highly connected to the peroxisome proliferator activated receptor and the retinoic acid receptor families. Endotype A, which had higher organ failure burden and mortality, exhibited a greater downregulation of Nrf2-linked genes than endotype B, with 92 genes differentially regulated between endotypes. Our findings indicate that Nrf2-linked genes may contribute to alterations in oxidative signaling and intermediary metabolism in pediatric septic shock.

Androgens and estrogens in benign prostatic hyperplasia: past, present and future

PubMed Central

Nicholson, Tristan M.; Ricke, William A.

2011-01-01

Benign prostatic hyperplasia (BPH) and associated lower urinary tract symptoms (LUTS) are common clinical problems in urology. While the precise molecular etiology remains unclear, sex steroids have been implicated in the development and maintenance of BPH. Sufficient data exists linking androgens and androgen receptor pathways to BPH and use of androgen reducing compounds, such as 5α-reductase inhibitors which block the conversion of testosterone into dihydrotestosterone, are a component of the standard of care for men with LUTS attributed to an enlarged prostate. However, BPH is a multifactorial disease and not all men respond well to currently available treatments, suggesting factors other than androgens are involved. Testosterone, the primary circulating androgen in men, can also be metabolized via CYP19/aromatase into the potent estrogen, estradiol-17β. The prostate is an estrogen target tissue and estrogens directly and indirectly affect growth and differentiation of prostate. The precise role of endogenous and exogenous estrogens in directly affecting prostate growth and differentiation in the context of BPH is an understudied area. Estrogens and selective estrogen receptor modulators (SERMs) have been shown to promote or inhibit prostate proliferation signifying potential roles in BPH. Recent research has demonstrated that estrogen receptor signaling pathways may be important in the development and maintenance of BPH and LUTS; however, new models are needed to genetically dissect estrogen regulated molecular mechanisms involved in BPH. More work is needed to identify estrogens and associated signaling pathways in BPH in order to target BPH with dietary and therapeutic SERMs. PMID:21620560

Emerging targets for the pharmacological treatment of depression: focus on melatonergic system.

PubMed

Catena-Dell'Osso, Mario; Marazziti, Donatella; Rotella, Francesco; Bellantuono, Cesario

2012-01-01

Depression is a disabling condition which adversely affects a person's family, social and work life, and that is associated with a heavy burden to society. Although the available antidepressants have shown their effectiveness and have greatly improved the prognosis of the disorder, the current management of depression is far from being satisfactory. In the last years, besides the classical research involving serotonin, norepineprine and dopamine, non-monoaminergic mechanisms have been explored in the attempt to discover new antidepressants. One such innovative approach focused on melatonergic system, as melatonin is involved in synchronizing circadian rhythms, which are known to be altered in depression. This narrative review aims to provide a comprehensive overview of different aspects of the melatonergic system, including biochemical and anatomical characteristics, impact on the sleep/wake system, and implications for the treatment of depression. In particular, the observation that melatonin may promote sleep and synchronize the internal clock led to development of high-affinity agonists for melatonin receptors (MT). Agomelatine, a naphthalene bioisostere of melatonin, which combines a potent MT1 and MT2 agonism with 5-HT(2C) receptor antagonism, has been found to be effective in the treatment of depressive and anxiety symptoms associated with major depression, with rapid and beneficial effects on the regulation of sleep continuity and quality. If substantiated by further evidence, the observation that melatonergic system dysfunctions contribute to the development of depression, as well as that the antidepressant action of agomelatine is linked to its binding properties to MT1/MT2 receptors, might open new avenues for the discovery of antidepressive agents.

Autonomic innervation of immune organs and neuroimmune modulation.

PubMed

Mignini, F; Streccioni, V; Amenta, F

2003-02-01

1. Increasing evidence indicates the occurrence of functional interconnections between immune and nervous systems, although data available on the mechanisms of this bi-directional cross-talking are frequently incomplete and not always focussed on their relevance for neuroimmune modulation. 2. Primary (bone marrow and thymus) and secondary (spleen and lymph nodes) lymphoid organs are supplied with an autonomic (mainly sympathetic) efferent innervation and with an afferent sensory innervation. Anatomical studies have revealed origin, pattern of distribution and targets of nerve fibre populations supplying lymphoid organs. 3. Classic (catecholamines and acetylcholine) and peptide transmitters of neural and non-neural origin are released in the lymphoid microenvironment and contribute to neuroimmune modulation. Neuropeptide Y, substance P, calcitonin gene-related peptide, and vasoactive intestinal peptide represent the neuropeptides most involved in neuroimmune modulation. 4. Immune cells and immune organs express specific receptors for (neuro)transmitters. These receptors have been shown to respond in vivo and/or in vitro to the neural substances and their manipulation can alter immune responses. Changes in immune function can also influence the distribution of nerves and the expression of neural receptors in lymphoid organs. 5. Data on different populations of nerve fibres supplying immune organs and their role in providing a link between nervous and immune systems are reviewed. Anatomical connections between nervous and immune systems represent the structural support of the complex network of immune responses. A detailed knowledge of interactions between nervous and immune systems may represent an important basis for the development of strategies for treating pathologies in which altered neuroimmune cross-talking may be involved.

The size of the hydroxyl group and its contribution to the affinity of atropine for muscarine-sensitive acetylcholine receptors.

PubMed Central

Barlow, R. B.; Ramtoola, S.

1980-01-01

1 From measurements of the affinity constants of hydratropyltropine and its methiodide for muscarine-sensitive acetylcholine receptors in the guinea-pig ileum, the increment in log K for the hydroxyl group in atropine is 2.06 and in the methiodide it is 2.16. These effects are slightly bigger than any so far recorded with these receptors. 2 The estimate of the increment in apparent molal volume for the hydroxyl group is 1.1 cm3/mol in atropine and 1.0 cm3/mol in the methobromide. 3 The large effect of the group on affinity may be linked to its small apparent size in water as suggested in the previous paper. PMID:7470742

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

Howard, A.D.

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 mgmore » 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.« less

Atropisomers of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) exhibit stereoselective effects on activation of nuclear receptors in vitro.

PubMed

Pěnčíková, Kateřina; Brenerová, Petra; Svržková, Lucie; Hrubá, Eva; Pálková, Lenka; Vondráček, Jan; Lehmler, Hans-Joachim; Machala, Miroslav

2017-11-09

PCB 136 is an environmentally relevant chiral PCB congener, which has been found in vivo to be present in form of rotational isomers (atropisomers). Its atropselective biotransformation or neurotoxic effects linked with sensitization of ryanodine receptor suggest that it might interact also with other intracellular receptors in a stereospecific manner. However, possible atropselective effects of PCB 136 on nuclear receptor transactivation remain unknown. Therefore, in this study, atropselective effects of PCB 136 on nuclear receptors controlling endocrine signaling and/or expression of xenobiotic and steroid hormone catabolism were investigated. PCB136 atropisomers were found to exert differential effects on estrogen receptor (ER) activation; (+)-PCB 136 was estrogenic, while (-)-PCB 136 was antiestrogenic. In contrast, inhibition of androgen receptor (AR) activity was not stereospecific. Both PCB136 stereoisomers induced the constitutive androgen receptor (CAR)-dependent gene expression; however, no significant stereospecificity of PCB 136 atropisomers was observed. PCB136 was a partial inducer of the pregnane X receptor (PXR)-dependent gene expression. Here, (-)-PCB 136 was a significantly more potent inducer of PXR activity than (+)-PCB 136. Taken together, the present results indicate that at least two nuclear receptors participating in endocrine regulation or metabolism, ER and PXR, could be regulated in an atropselective manner by chiral PCB 136. The enantioselective enrichment of PCB atropisomers in animal and human tissues may thus have significant consequences for endocrine-disrupting effects of chiral ortho-substituted PCB congeners.

Dietary ω-3 Polyunsaturated Fatty Acids Inhibit Tumor Growth in Transgenic ApcMin/+ Mice, Correlating with CB1 Receptor Up-Regulation

PubMed Central

Notarnicola, Maria; Tutino, Valeria; De Nunzio, Valentina; Dituri, Francesco; Caruso, Maria Gabriella; Giannelli, Gianluigi

2017-01-01

Mediterranean diet components, such as olive oil and ω-3 polyunsaturated fatty acids (ω-3 PUFAs), can arrest cell growth and promote cell apoptosis. Recently, olive oil has been demonstrated to modulate type-1 cannabinoid (CB1) receptor gene expression in both human colon cancer cells and rat colon. The aim of this study was to investigate a possible link between olive oil and ω-3 PUFAs effects and CB1 receptor expression in both intestinal and adipose tissue of ApcMin/+ mice. To confirm the role for the CB1 receptor as a negative modulator of cell proliferation in human colon cancer, CB1 receptor gene expression was also detected in tumor tissue and in surrounding normal mucosa of patients with colorectal cancer (CRC). Dietary ω-3 PUFAs significantly inhibited intestinal polyp growth in mice, correlating with CB1 receptor gene and protein expression induction. CB1 receptor gene up-regulation was also detected in adipose tissue, suggesting a close communication between cancer cells and the surrounding environment. Tissue CB1 receptor induction was associated with a concurrent inactivation of the Wnt/β-catenin pathway. Moreover, there was a significant reduction in CB1 receptor gene expression levels in cancer tissue compared to normal surrounding mucosa of patients with CRC, confirming that in cancer the “protective” action of the CB1 receptor is lost. PMID:28245562

Diverse roles for ionotropic glutamate receptors on inhibitory interneurons in developing and adult brain.

PubMed

Akgül, Gülcan; McBain, Chris J

2016-10-01

Glutamate receptor-mediated recruitment of GABAergic inhibitory interneurons is a critical determinant of network processing. Early studies observed that many, but not all, interneuron glutamatergic synapses contain AMPA receptors that are GluA2-subunit lacking and Ca(2+) permeable, making them distinct from AMPA receptors at most principal cell synapses. Subsequent studies demonstrated considerable alignment of synaptic AMPA and NMDA receptor subunit composition within specific subtypes of interneurons, suggesting that both receptor expression profiles are developmentally and functionally linked. Indeed glutamate receptor expression profiles are largely predicted by the embryonic origins of cortical interneurons within the medial and caudal ganglionic eminences of the developing telencephalon. Distinct complements of AMPA and NMDA receptors within different interneuron subpopulations contribute to the differential recruitment of functionally divergent interneuron subtypes by common afferent inputs for appropriate feed-forward and feedback inhibitory drive and network entrainment. In contrast, the lesser-studied kainate receptors, which are often present at both pre- and postsynaptic sites, appear to follow an independent developmental expression profile. Loss of specific ionotropic glutamate receptor (iGluR) subunits during interneuron development has dramatic consequences for both cellular and network function, often precipitating circuit inhibition-excitation imbalances and in some cases lethality. Here we briefly review recent findings highlighting the roles of iGluRs in interneuron development. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

The Intracellular Juxtamembrane Domain of the Epidermal Growth Factor (EGF) Receptor Is Responsible for the Allosteric Regulation of EGF Binding*S⃞♦

PubMed Central

Macdonald-Obermann, Jennifer L.; Pike, Linda J.

2009-01-01

We have previously shown that the binding of epidermal growth factor (EGF) to its receptor can best be described by a model that involves negative cooperativity in an aggregating system (Macdonald, J. L., and Pike, L. J. (2008) Proc. Natl. Acad. Sci. U. S. A. 105, 112–117). However, despite the fact that biochemical analyses indicate that EGF induces dimerization of its receptor, the binding data provided no evidence for positive linkage between EGF binding and dimer assembly. By analyzing the binding of EGF to a number of receptor mutants, we now report that in naive, unphosphorylated EGF receptors, ligand binding is positively linked to receptor dimerization but the linkage is abolished upon autophosphorylation of the receptor. Both phosphorylated and unphosphorylated EGF receptors exhibit negative cooperativity, indicating that mechanistically, cooperativity is distinct from the phenomenon of linkage. Nonetheless, both the positive linkage and the negative cooperativity observed in EGF binding require the presence of the intracellular juxtamembrane domain. This indicates the existence of inside-out signaling in the EGF receptor system. The intracellular juxtamembrane domain has previously been shown to be required for the activation of the EGF receptor tyrosine kinase (Thiel, K. W., and Carpenter, G. (2007) Proc. Natl. Acad. Sci. U. S. A. 104, 19238–19243). Our experiments expand the role of this domain to include the allosteric control of ligand binding by the extracellular domain. PMID:19336395

Substance P Receptor Signaling Mediates Doxorubicin-Induced Cardiomyocyte Apoptosis and Triple-Negative Breast Cancer Chemoresistance

PubMed Central

Robinson, Prema; Kasembeli, Moses; Bharadwaj, Uddalak; Engineer, Nikita; Eckols, Kris T.; Tweardy, David J.

2016-01-01

Doxorubicin (DOX), an anthracycline, is broadly considered the most active single agent available for treating breast cancer but has been known to induce cardiotoxicity. Although DOX is highly effective in treating triple-negative breast cancer (TNBC), DOX can have poor outcomes owing to induction of chemoresistance. There is an urgent need to develop new therapies for TNBC aimed at improving DOX outcome and DOX-induced cardiotoxicity. Substance P (SP), a neuropeptide involved in pain transmission is known to stimulate production of reactive oxygen species (ROS). Elevated cardiac ROS is linked with heart injury and failure. We investigated the role of SP in chemotherapy-associated death of cardiomyocytes and chemoresistance. We showed that pretreating a cardiomyocyte cell line (H9C2) and a TNBC cell line (MDA-MB 231) with aprepitant, a SP receptor antagonist that is routinely used to treat chemotherapy-associated associated nausea, decreased DOX-induced reduction of cell viability, apoptotic cell death, and ROS production in cardiomyocytes and increased DOX-induced reduction of cell viability, apoptotic cell death, and ROS production in TNBC cells compared with cells treated with DOX alone. Our findings demonstrate the ability of aprepitant to decrease DOX-induced killing of cardiomyocytes and to increase cancer cell sensitivity to DOX, which has tremendous clinical significance. PMID:26981525